file: solabs_cadavid.html = solar physics author: cadavid
      ADS abstracts papers/articles/publications/books by: cadavid
last: Oct 16 2014
      explanation     parallel bibtex collection for author: cadavid 
    

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Title:              Heating Mechanisms for Intermittent Loops in Active 
                    Region Cores from AIA/SDO EUV Observations
Authors:            Cadavid, A. C.; Lawrence, J. K.; Christian, D. J.;
                    Jess, D. B.; Nigro, G.
Bibliographic Code: 2014arXiv1404.7824C     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
We investigate intensity variations and energy deposition in five 
coronal loops in active region cores. These were selected for their 
strong variability in the AIA/SDO 94 {\AA} intensity channel. We isolate 
the hot Fe XVIII and Fe XXI components of the 94 {\AA} and 131 {\AA} by 
modeling and subtracting the "warm" contributions to the emission. 
HMI/SDO data allow us to concentrate on "inter-moss" regions in the 
loops. The detailed evolution of the inter-moss intensity time series 
reveals loops that are impulsively heated in a mode compatible with a 
nanoflare storm, with a spike in the hot 131 {\AA} signals leading and 
the other five EUV emission channels following in progressive cooling 
order. A sharp increase in electron temperature tends to follow closely 
after the hot 131 {\AA} signal confirming the impulsive nature of the 
process. A cooler process of growing emission measure follows more 
slowly. The Fourier power spectra of the hot 131 {\AA} signals, when 
averaged over the five loops, present three scaling regimes with break 
frequencies at (0.1/min) and (0.7/min). The low frequency regime 
corresponds to 1/f noise; the intermediate indicates a persistent 
scaling process and the high frequencies show white noise. Very similar 
results are found for the energy dissipation in a 2-D "hybrid" shell 
model of loop magneto-turbulence, based on reduced magnetohydrodynamics, 
which is compatible with nanoflare statistics. We suggest that such 
turbulent dissipation is the energy source for our loops. 

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Title:              Different Periodicities in the Sunspot Area and the 
                    Occurrence of Solar Flares and Coronal Mass 
                    Ejections in Solar Cycle 23 - 24
Authors:            Choudhary, D. P.; Lawrence, J. K.; Norris, M.;
                    Cadavid, A. C.
Bibliographic Code: 2014SoPh..289..649C      
    Paper (if ADS pdf and access)    ADS page 

In order to investigate the relationship between magnetic-flux 
emergence, solar flares, and coronal mass ejections (CMEs), we study the 
periodicity in the time series of these quantities. It has been known 
that solar flares, sunspot area, and photospheric magnetic flux have a 
dominant periodicity of about 155 days, which is confined to a part of 
the phase of the solar cycle. These periodicities occur at different 
phases of the solar cycle during successive phases. We present a 
time-series analysis of sunspot area, flare and CME occurrence during 
Cycle 23 and the rising phase of Cycle 24 from 1996 to 2011. We find 
that the flux emergence, represented by sunspot area, has multiple 
periodicities. Flares and CMEs, however, do not occur with the same 
period as the flux emergence. Using the results of this study, we 
discuss the possible activity sources producing emerging flux. 

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Title:              Intermittent and Scale-Invariant Intensity 
                    Fluctuations in Hot Coronal Loops
Authors:            Lawrence, J. K.; Cadavid, A. C.; Christian, D. J.;
                    Jess, D. B.; Nigro, G.
Bibliographic Code: 2013AGUFMSH33A2041L
      
    Paper (if ADS pdf and access)    ADS page 

ABSTRACT BODY: To resolve outstanding questions on heating of coronal 
loops, we study intensity fluctuations in inter-moss portions of active 
region core loops as observed with AIA/SDO. The 94 fluctuations 
(Figure 1) have structure on timescales shorter than radiative and 
conductive cooling times. Each of several strong 94 brightenings 
is followed after ~8 min by a broader peak in the cooler 335 
emission. This indicates that we see emission from the hot component of 
the 94 contribution function. No hotter contributions appear, and 
we conclude that the 94 intensity can be used as a proxy for 
energy injection into the loop plasma. The probability density function 
of the observed 94 intensity has 'heavy tails' that approach zero 
more slowly than the tails of a normal distribution. Hence, large 
fluctuations dominate the behavior of the system. The resulting 
'intermittence' is associated with power-law or exponential scaling of 
the related variables, and these in turn are associated with turbulent 
phenomena. The intensity plots in Figure 1 resemble multifractal time 
series, which are common to various forms of turbulent energy 
dissipation. In these systems a single fractal dimension is insufficient 
to describe the dynamics and instead there is a spectrum of fractal 
dimensions that quantify the self-similar properties. Figure 2 shows the 
multifractal spectrum from our data to be invariant over timescales from 
24 s to 6.4 min. We compare these results to outputs from theoretical 
energy dissipation models based on MHD turbulence, and in some cases we 
find substantial agreement, in terms of intermittence, multifractality 
and scale invariance. Figure 1. Time traces of 94A intensity in the 
inter-moss portions of four AR core loops. 
Figure 2. Multifractal spectra showing timescale invariance. The four 
cases of Figure 1 are included. 

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Title:              Evolution of Hot Loops in an Active Region Core 
                    Observed with the SDO Atmospheric Image Assembly
Authors:            Cadavid, A. C.; Lawrence, J. K.; Christian, D. J.;
                    Jess, D. B.
Bibliographic Code: 2013AGUFMSH33A2037C
      
    Paper (if ADS pdf and access)    ADS page 

Evidence has accumulated of high temperature (> 4 MK) coronal 
emission in active region cores that corresponds to structures in 
equilibrium. Other studies have found evidence of evolving loops. We 
investigate the EUV intensity and temperature variations of short 
coronal loops observed in the core of NOAA Active Region 11250 on 13 
July 2011. The loops, which run directly between the AR opposite 
polarities, are first detectable in the 94 band of Fe XVIII, 
implying an effective temperature ~ 7 MK. The low temperature component 
of the 94  signal is modeled in terms of a linear superposition 
of the 193  and 171  signals in order to separate the hot 
component. After identifying the loops we have used contemporaneous HMI 
observations to identify the corresponding inter-moss regions, and we 
have investigated their time evolution in six AIA EUV channels. The 
results can be separated into two classes. Group 1 (94, 
335, 211) is characterized by hotter temperatures (~2-7 
MK), and Group 2 (193, 171, 131) by cooler 
temperatures (0.4 - 1.6 MK). For Group 1 the intensity peaks in the 
94 channel are followed by maxima in the 335  channel with 
a time lag of ~8 min, suggestive of a cooling pattern with an 
exponential decay. While the 211 maxima follow those in the 335 
 channel, there is no systematic relation which would indicate a 
progressive cooling process through the lower temperatures, as has been 
observed in other investigations. In Group 2 the signals in the 171 and 
131 channels track each other closely, and lag behind the 
193. In the inter-moss region of the loop the peak temperature 
and peak emission measure have opposite trends. The hot 94 
brightenings occur in the central part of the loops with maximum 
temperatures ~7 MK. Subsequently the loops appear to fill with plasma 
with an emission measure compatible with the 193  signal and 
temperature in the range ~ 1.5-2 MK. Although the exact details of the 
time evolution are still under investigation, these non static loops 
show high levels of intermittency in the 94 signal (please see 
poster "Intermittent and Scale-Invariant Intensity Fluctuations in Hot 
Coronal Loops," by Lawrence et al. in this session). 

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Title:              Incorporating Student Activities into Climate Change 
                    Education
Authors:            Steele, H.; Kelly, K.; Klein, D.; Cadavid, A. C.
Bibliographic Code: 2013AGUFMED31E..05S
      
    Paper (if ADS pdf and access)    ADS page 

Under a NASA grant, Mathematical and Geospatial Pathways to Climate 
Change Education, students at California State University, Northridge 
integrated Geographic Information Systems (GIS), remote sensing, 
satellite data technologies, and climate modelling into the study of 
global climate change under a Pathway for studying the Mathematics of 
Climate Change (PMCC). The PMCC, which is an interdisciplinary option 
within the BS in Applied Mathematical Sciences, consists of courses 
offered by the departments of Mathematics, Physics, and Geography and is 
designed to prepare students for careers and Ph.D. programs in technical 
fields relevant to global climate change. Under this option students are 
exposed to the science, mathematics, and applications of climate change 
science through a variety of methods including hands-on experience with 
computer modeling and image processing software. In the Geography 
component of the program, ESRI's ArcGIS and ERDAS Imagine mapping, 
spatial analysis and image processing software were used to explore NASA 
satellite data to examine the earth's atmosphere, hydrosphere and 
biosphere in areas that are affected by climate change or affect 
climate. These technology tools were incorporated into climate change 
and remote sensing courses to enhance students' knowledge and 
understanding of climate change through hands-on application of image 
processing techniques to NASA data. Several sets of exercises were 
developed with specific learning objectives in mind. These were (1) to 
increase student understanding of climate change and climate change 
processes; (2) to develop student skills in understanding, downloading 
and processing satellite data; (3) to teach remote sensing technology 
and GIS through applications to climate change; (4) to expose students 
to climate data and methods they can apply to solve real world problems 
and incorporate in future research projects. In the Math and Physics 
components of the course, students learned about atmospheric circulation 
with applications of the Lorenz model, explored the land-sea breeze 
problem with the Dynamics and Thermodynamics Circulation Model (DTDM), 
and developed simple radiative transfer models. Class projects explored 
the effects of varying the content of CO2 and CH4 in the atmosphere, as 
well as the properties of paleoclimates in atmospheric simulations using 
EdGCM. Initial assessment of student knowledge, attitudes, and behaviors 
associated with these activities, particularly about climate change, was 
measured. Pre- and post-course surveys provided student perspectives 
about the courses and their learning about remote sensing and climate 
change concepts. Student performance on the tutorials and course 
projects evaluated students' ability to learn and apply their knowledge 
about climate change and skills with remote sensing to assigned problems 
or proposed projects of their choice. Survey and performance data 
illustrated that the exercises were successful in meeting their intended 
learning objectives as well as opportunities for further refinement and 
expansion. 

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Title:              Non-steady, Intermittent, Hot Loops in an Active 
                    Region Observed with the SDO/AIA
Authors:            Cadavid, Ana C.; Lawrence, J. K.; Christian, D. J.
Bibliographic Code: 2013SPD....44...48C
      
    Paper (if ADS pdf and access)    ADS page 

While there is accumulated evidence of high temperature coronal emission 
in active region cores that corresponds to structures in equilibrium, 
other studies have found of evolving loops. We investigate the EUV 
intensity variations of two low and short coronal loops observed in the 
core of NOAA AR 11250 on 13 July 2011 between UT 12:02 and 16:32. The 
loops (32 Mm loop 1, 23 Mm loop 2), run directly between the AR opposite 
polarities, and are first detectable in the 94 band (effective 
temperature ~ 7 MK). Space-time slices present intermittent brightenings 
evocative of turbulence. Spatial averages over the intermoss loop region 
lead to light curves used to analyze the temporal evolution of the 
loops. We find quantities with scaling regimes that are characteristic 
of intermittent processes. In particular intensity histograms display 
scaling ranges with slopes ~ -1.8, and spectra also show a scaling 
region for frequencies 1-8 mHz, with slopes - 3.8 (loop 1) and -2.8 
(loop 2). We further investigate the time evolution of the loops in five 
other AIA EUV channels. The results are separated into two classes. 
Group A (94, 335, 211) characterized by hotter 
temperatures  2-6 MK), and group B (193, 171, 131) 
by cooler temperatures (0.4 - 1.6 MK). In loop 1 (group A) the intensity 
peaks in the 94 channel are followed by maxima in the 335  
channel with a time lag of ~10 min, suggestive of a cooling pattern with 
an exponential decay. The 211 maxima follow those in the 335 
 channel, but there is no systematic relation which would 
indicate a progressive cooling process. In group B the signals in the 
171 and 131 channels track each other closely, and tend to lag 
behind the 193. The three signals follow a general gradual 
increase reaching a maximum at about the middle of the time series and 
then decrease. An exponential cooling model can also be associated with 
the 193 and 171 pair. For loop 2 the observations in the group B 
light curves present similar properties as in loop 1. In contrast the 
intensity curves in group A only show one distinct case which could be a 
candidate for exponential decay via a 94  to 335  cooling 
process.Abstract (2,250 Maximum Characters): While there is accumulated 
evidence of high temperature coronal emission in active region cores 
that corresponds to structures in equilibrium, other studies have found 
of evolving loops. We investigate the EUV intensity variations of two 
low and short coronal loops observed in the core of NOAA AR 11250 on 13 
July 2011 between UT 12:02 and 16:32. The loops (32 Mm loop 1, 23 Mm 
loop 2), run directly between the AR opposite polarities, and are first 
detectable in the 94 band (effective temperature ~ 7 MK). 
Space-time slices present intermittent brightenings evocative of 
turbulence. Spatial averages over the intermoss loop region lead to 
light curves used to analyze the temporal evolution of the loops. We 
find quantities with scaling regimes that are characteristic of 
intermittent processes. In particular intensity histograms display 
scaling ranges with slopes ~ -1.8, and spectra also show a scaling 
region for frequencies 1-8 mHz, with slopes - 3.8 (loop 1) and -2.8 
(loop 2). We further investigate the time evolution of the loops in five 
other AIA EUV channels. The results are separated into two classes. 
Group A (94, 335, 211) characterized by hotter 
temperatures  2-6 MK), and group B (193, 171, 131) 
by cooler temperatures (0.4 - 1.6 MK). In loop 1 (group A) the intensity 
peaks in the 94 channel are followed by maxima in the 335  
channel with a time lag of ~10 min, suggestive of a cooling pattern with 
an exponential decay. The 211 maxima follow those in the 335 
 channel, but there is no systematic relation which would 
indicate a progressive cooling process. In group B the signals in the 
171 and 131 channels track each other closely, and tend to lag 
behind the 193. The three signals follow a general gradual 
increase reaching a maximum at about the middle of the time series and 
then decrease. An exponential cooling model can also be associated with 
the 193 and 171 pair. For loop 2 the observations in the group B 
light curves present similar properties as in loop 1. In contrast the 
intensity curves in group A only show one distinct case which could be a 
candidate for exponential decay via a 94  to 335  cooling 
process. 

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Title:              Turbulent Fluctuations in G-band and K-line 
                    Intensities Observed with the Rapid Oscillations in 
                    the Solar Atmosphere (ROSA) Instrument
Authors:            Cadavid, A. C.; Lawrence, J. K.; Christian, D. J.;
                    Jess, D. B.; Mathioudakis, M.
Bibliographic Code: 2012ASPC..463...75C
      
    Paper (if ADS pdf and access)    ADS page 

Using the Rapid Oscillation in the Solar Atmosphere (ROSA) instrument at 
the Dunn Solar Telescope  we have found that the spectra of fluctuations 
of the G-band (cadence 1.05 s) and Ca II K-line  (cadence 4.2 s) 
intensities show correlated fluctuations above white noise out to 
frequencies  beyond 300 mHz and up to 70 mHz, respectively. The 
noise-corrected G-band spectrum presents a   scaling range  (Ultra High 
Frequency ``UHF'') for f = 25-100 mHz,  with an exponent 
 consistent with the presence of turbulent motions. The UHF power, is 
concentrated at the  locations of magnetic bright points in the 
intergranular lanes, it is   highly intermittent in time and 
characterized by a positive kurtosis kappa. Combining  values of 
G-band and K-line intensities, the UHF power, and kappa, reveals two 
distinct ``states'' of the internetwork solar atmosphere. 
State 1, with kappa ≈ 6, which includes almost all  the data, is 
characterized by low intensities and low UHF power. State 2, with 
kappa ≈ 3,  including a very small fraction of the data, is 
characterized by high intensities and high UHF power.   Superposed epoch 
analysis shows that for  State 1, the K-line intensity  presents 3.5 min 
chromospheric oscillations with maxima occurring 21 s after G-band 
intensity  maxima implying a  150-210 km effective height 
difference. For State 2, the G-band and K-line intensity  maxima  are 
simultaneous, suggesting that in the highly magnetized environment sites 
of G-band  and K-line emission may be spatially close together. Analysis 
of  observations obtained with Hinode/SOT   confirm a scaling range in 
the G-band spectrum up to 53 mHz also consistent with turbulent  motions 
as well as the identification of two distinct states in terms of the 
H-line  intensity and G-band power as functions of G-band intensity. 

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Title:              2nd ATST-EAST Workshop in Solar Physics: Magnetic 
                    Fields from the Photosphere to the Corona
Authors:            Rimmele, T. R.; Tritschler, A.; Wger, F.;
                    Collados Vera, M.; Socas-Navarro, H.;
                    Schlichenmaier, R.; Carlsson, M.; Berger, T.;
                    Cadavid, A.; Gilbert, P. R.; Goode, P. R.;
                    Knlker, M.
Bibliographic Code: 2012ASPC..463.....R
      
    Paper (if ADS pdf and access)    ADS page 


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Title:              Coupled Effects of a Perturbation in a Complex 
                    Structure Observed with SDO/AIA, SDO/HMI and 
                    ROSA/HARDcam
Authors:            Cadavid, A. C.; Lawrence, J. K.; Christian, D. J.;
                    Jess, D. B.; Mathioudakis, M.
Bibliographic Code: 2012AGUFMSH51A2197C
      
    Paper (if ADS pdf and access)    ADS page 

We study properties of intensity fluctuations in NOAA Active Region 
11250 observed on 13 July 2011 starting at UT 13:32. Included are data 
obtained in the EUV bands of the Atmospheric Imaging Assembly on board 
the Solar Dynamics Observatory (SDO/AIA) as well as nearly simultaneous 
observations of the chromosphere made, at much higher spatial and 
temporal resolution, with the Rapid Oscillations in the Solar Atmosphere 
(ROSA) and Hydrogen-Alpha Rapid Dynamics camera (HARDcam) systems at the 
Dunn Solar Telescope. A complex structure seen in both the ROSA/HARDcam 
and SDO data sets comprises a system of loops extending outward from 
near the boundary of the leading sunspot umbra. It is visible in the 
ROSA Ca II K and HARDcam Halpha images, as well as the SDO 304 
, 171  and 193  channels, and it thus couples the 
chromosphere, transition region and corona. In the ground-based images 
the loop structure is 4.1 Mm long. Some 17.5 Mm, can be traced in the 
SDO/AIA data. The chromospheric emissions observed by ROSA and HARDcam 
appear to occupy the inner, and apparently cooler and lower, quarter of 
the loop. We compare the intensity fluctuations of two points within the 
structure. From alignment with SDO/HMI images we identify a point "A" 
near the loop structure, which sits directly above a bipolar magnetic 
feature in the photosphere. Point "B" is characteristic of locations 
within the loops that are visible in both the ROSA/HARDcam and the 
SDO/AIA data. The intensity traces for point A are quiet during the 
first part of the data string. At time ~ 19 min they suddenly begin a 
series of impulsive brightenings. In the 171  and 193  
coronal lines the brightenings are localized impulses in time, but in 
the transition region line at 304  they are more extended in 
time. The intensity traces in the 304  line for point B shows a 
quasi-periodic signal that changes properties at about 19 min. The 
wavelet power spectra are characterized by two periodicities. A 6.7 min 
period extends from the beginning of the series until about 25 minutes, 
and another signal with period ~3 min starts at about 20 min. The 193 
 power spectrum has a characteristic period of 5 min, before the 
20 min transition and a 2.5 min periodicity afterward. In the case of 
HARDcam Halpha data a localized 4 min periodicity can be found until 
about 7 min, followed by a quiet regime. After ~20 min a 2.3 min 
periodicity appears. Interestingly a coronal loop visible in the 94 
 line that is centrally located in the AR, running from the 
leading umbra to the following polarity, at about time 20 min undergoes 
a strong brightening beginning at the same moment all along 15 Mm of its 
length. The fact that these different signals all experience a clear-cut 
change at time about 20 min suggests an underlying organizing mechanism. 
Given that point A has a direct connection to the photospheric magnetic 
bipole, we conjecture that the whole extended structure is connected in 
a complex manner to the underlying magnetic field. The periodicities in 
these features may favor the wave nature rather than upflows and 
interpretations will be discussed. 

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Title:              Coupled Intensity Variations in Hot Coronal Loops 
                    Observed with SDO/AIA
Authors:            Lawrence, J. K.; Cadavid, A. C.; Christian, D. J.
Bibliographic Code: 2012AGUFMSH33D2265L
      
    Paper (if ADS pdf and access)    ADS page 

Data from the AIA on board SDO allow us to study EUV intensity 
variations of coronal loops. Here we study strong EUV brightenings of 
coronal loops in NOAA Active Region 11250 on 13 July 2011 between UT 
13:32 and 14:32. The brightenings are seen only in the 94 band of 
Fe XVIII, implying an effective temperature ~ 8 MK. The relevant loops 
run directly between the AR opposite polarities and are low and short. 
One example is an apparently single loop north of the AR midline. At UT 
13:50 (18 min into the observational sequence - see the image) it began 
a strong brightening in the 94  band. This occurred at the same 
moment all along 15 Mm of its length to ~ 12 s accuracy. This suggests 
the presence of stored free energy along the loop that was released by 
an instability that must have propagated along it at 1500 km/s or 
faster. The maximum rate of increase of the 94  intensity 
occurred at 20 min into the sequence, and the maximum was reached at 23 
min. It then decayed, reaching its former level at time 40 min. Another 
example lay south of the AR midline (see the image). On its trailing end 
this loop had two feet, suggesting that it is a superposition of two 
loops seen in projection. This structure showed two strong 94  
brightenings peaking at 32 min and 37 min into the data sequence. The 
first brightening was associated with an intensity increase in the 
northern trailing foot, while the second was associated with an 
intensity increase in the southern foot. Again, this points to the 
presence of two superimposed loops. Brightenings in the loop feet 
indicate upward motion of intensity features toward the loop center at 
various speeds from 50 - 200 km/s. The intensity in the central loop 
section shows a sequence of weaker increases at 4 min intervals 
preceding the strong brightenings and a still weaker sequence at 5 min 
intervals afterward. These indicate releases of stored energy along a 10 
Mm loop segment by a periodically repeating instability. The onset of 
the periodic energy releases in Example 2 and also the start of the loop 
brightening in Example 1 both occur at time 18 min into the data 
sequence. This coincides with the time of disturbances in other features 
of AR 11250 and suggests a complex coupling among its various 
structures.; SDO/AIA images of AR11250 made in the EUV 94  band 
at UT 13:53 and 14:03 on 13 July 2011. The images are 94 Mm wide. The 
grayscale is reversed. 

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Title:              STEPS at CSUN: Increasing Retention of Engineering 
                    and Physical Science Majors
Authors:            Pedone, V. A.; Cadavid, A. C.; Horn, W.
Bibliographic Code: 2012AGUFMED51B0886P
      
    Paper (if ADS pdf and access)    ADS page 

STEPS at CSUN seeks to increase the retention rate of first-time 
freshman in engineering, math, and physical science (STEM) majors from 
~55% to 65%. About 40% of STEM first-time freshmen start in College 
Algebra because they do not take or do not pass the Mathematics 
Placement Test (MPT). This lengthens time to graduation, which 
contributes to dissatisfaction with major. STEPS at CSUN has made 
substantial changes to the administration of the MPT. Initial data show 
increases in the number of students who take the test and who place out 
of College Algebra, as well as increases in overall scores. STEPS at 
CSUN also funded the development of supplemental labs for Trigonometry 
and Calculus I and II, in partnership with similar labs created by the 
Math Department for College Algebra and Precalculus. These labs are open 
to all students, but are mandatory for at-risk students who have low 
scores on the MPT, low grades in the prerequisite course, or who failed 
the class the first time. Initial results are promising. Comparison of 
the grades of 46 Fall 2010 "at-risk" students without lab to those of 36 
Fall 2011 students who enrolled in the supplementary lab show D-F grades 
decreased by 10% and A-B grades increased by 27%. A final retention 
strategy is aimed at students in the early stages of their majors. At 
CSUN the greatest loss of STEM majors occurs between sophomore-level and 
junior-level coursework because course difficulty increases and 
aspirations to potential careers weaken. The Summer Interdisciplinary 
Team Experience (SITE) is an intensive 3-week-long summer program that 
engages small teams of students from diverse STEM majors in 
faculty-mentored, team-based problem solving. This experience simulates 
professional work and creates strong bonds between students and between 
students and faculty mentors. The first two cohorts of students who have 
participated in SITE indicate that this experience has positively 
impacted their motivation to complete their STEM degree. 

@--------------------------------------------------------------------
Title:              Climate Science Program at California State 
                    University, Northridge
Authors:            Steele Cox, H.; Klein, D.; Cadavid, A. C.; Foley, B.
Bibliographic Code: 2012AGUFMED33A0746S
      
    Paper (if ADS pdf and access)    ADS page 

Due to its interdisciplinary nature, climate science poses wide-ranging 
challenges for science and mathematics students seeking careers in this 
field. There is a compelling need for universities to provide coherent 
programs in climate science in order to train future climate scientists. 
With funding from NASA Innovations in Climate Education (NICE), 
California State University, Northridge (CSUN), is creating the CSUN 
Climate Science Program. An interdisciplinary team of faculty members is 
working in collaboration with UCLA, Santa Monica College and NASA/JPL 
partners to create a new curriculum in climate science. The resulting 
sequence of climate science courses, or Pathway for studying the 
Mathematics of Climate Change (PMCC), is integrated into a Bachelor of 
Science degree program in the Applied Mathematical Sciences offered by 
the Mathematics Department at CSUN. The PMCC consists of courses offered 
by the departments of Mathematics, Physics, and Geography and is 
designed to prepare students for Ph.D. programs in technical fields 
relevant to global climate change and related careers. The students who 
choose to follow this program will be guided to enroll in the following 
sequence of courses for their 12 units of upper division electives: 1) A 
newly created course junior level course, Math 396CL, in applied 
mathematics which will introduce students to applications of vector 
calculus and differential equations to the study of thermodynamics and 
atmospheric dynamics. 2) An already existing course, Math 483, with new 
content on mathematical modeling specialized for this program; 3) An 
improved version of Phys 595CL on the mathematics and physics of climate 
change with emphasis on Radiative Transfer; 4) A choice of Geog 407 on 
Remote Sensing or Geog 416 on Climate Change with updated content to 
train the students in the analysis of satellite data obtained with the 
NASA Earth Observing System and instruction in the analysis of data 
obtained within a Geographical Information System (GIS). In addition the 
Geography department will similarly update the corresponding graduate 
courses on Remote Sensing, Geog 690D, and Climate Change Geog 620F, and 
there will be a reciprocal curriculum and data sharing collaboration 
with the Earth and Environmental Sciences program at Santa Monica 
College. Throughout the academic year a seminar series offers the 
students the opportunity to learn about ongoing work on Atmospheric 
Sciences and Climate and during the summer they have access to research 
experiences at NASA's Jet Propulsion Laboratory. 

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Title:              CPV hybrid system in ISFOC building, first results
Authors:            Trujillo, Pablo; Alamillo, Csar; Gil, Eduardo;
                    de la Rubia, scar; Martnez, Mara;
                    Rubio, Francisca; Cadavid, Andros; Navarro, Jos
                    Hillenbrand, Sascha; Ballesteros-Snchez, Isabel;
                    Castillo-Cagigal, Manuel; Masa-Bote, Daniel;
                    Matallanas, Eduardo; Caamao-Martn, Estefana;
                    Gutirrez, lvaro
Bibliographic Code: 2012AIPC.1477..360T
      
    Paper (if ADS pdf and access)    ADS page 

PV Off-Grid systems have demonstrated to be a good solution for the 
electrification of remote areas [1]. A hybrid system is one kind of 
these systems. The principal characteristic is that it uses PV as the 
main generator and has a backup power supply, like a diesel generator, 
for instance, that is used when the CPV generation is not enough to meet 
demand. To study the use of CPV in these systems, ISFOC has installed a 
demonstration hybrid system at its headquarters. This hybrid system uses 
CPV technology as main generator and the utility grid as the backup 
generator. A group of batteries have been mounted as well to store the 
remaining energy from the CPV generator when nedeed. The energy flows 
are managed by a SMA system based on Sunny Island inverters and a 
Multicluster-Box (figure 1). The Load is the air-conditioning system of 
the building, as it has a consumption profile higher than the CPV 
generator and can be controlled by software [2]. The first results of 
this system, as well as the first chances of improvement, as the need of 
a bigger CPV generator and a better management of the energy stored in 
the batteries, are presented in this paper. 

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Title:              Observed Effect of Magnetic Fields on the 
                    Propagation of Magnetoacoustic Waves in the Lower 
                    Solar Atmosphere
Authors:            Lawrence, J. K.; Cadavid, A. C.
Bibliographic Code: 2012SoPh..280..125L     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
We study Hinode/SOT-FG observations of intensity fluctuations in Ca ii 
H-line and G-band image sequences and their relation to simultaneous and 
co-spatial magnetic field measurements. We explore the G-band and H-line 
intensity oscillation spectra both separately and comparatively via 
their relative phase differences, time delays and cross-coherences. In 
the non-magnetic situations, both sets of fluctuations show strong 
oscillatory power in the 3 - 7 mHz band centered at 4.5 mHz, but this is 
suppressed as magnetic field increases. A relative phase analysis gives 
a time delay of H-line after G-band of 201 s in non-magnetic 
situations implying a mean effective height difference of 140 km. The 
maximum coherence is at 4 - 7 mHz. Under strong magnetic influence the 
measured delay time shrinks to 11 s with the peak coherence near 4 mHz. 
A second coherence maximum appears between 7.5 - 10 mHz. Investigation 
of the locations of this doubled-frequency coherence locates it in 
diffuse rings outside photospheric magnetic structures. Some possible 
interpretations of these results are offered. 

@--------------------------------------------------------------------
Title:              Rapid Fluctuations in the Lower Solar Atmosphere
Authors:            Lawrence, J. K.; Cadavid, A. C.; Christian, D. J.;
                    Jess, D. B.; Mathioudakis, M.
Bibliographic Code: 2011ApJ...743L..24L     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
The Rapid Oscillations in the Solar Atmosphere instrument reveals solar 
atmospheric fluctuations at high frequencies. Spectra of variations of 
the G-band intensity (I<SUB>G</SUB> ) and Ca II K-line intensity 
(I<SUB>K</SUB> ) show correlated fluctuations above white noise to 
frequencies beyond 300 mHz and 50 mHz, respectively. The noise-corrected 
G-band spectrum for f = 28-326 mHz shows a power law with exponent -1.21 
 0.02, consistent with the presence of turbulent motions. G-band 
spectral power in the 25-100 mHz ("UHF") range is concentrated at the 
locations of magnetic bright points in the intergranular lanes and is 
highly intermittent in time. The intermittence of the UHF G-band 
fluctuations, shown by a positive kurtosis kappa, also suggests 
turbulence. Combining values of I<SUB>G</SUB> , I<SUB>K</SUB> , UHF 
power, and kappa reveals two distinct states of the solar atmosphere. 
State 1, including almost all the data, is characterized by low 
I<SUB>G</SUB> , I<SUB>K</SUB> , and UHF power and kappa &ap; 6. State 
2, including only a very small fraction of the data, is characterized by 
high I<SUB>G</SUB> , I<SUB>K</SUB> , and UHF power and kappa &ap; 3. 
Superposed epoch analysis shows that the UHF power peaks simultaneously 
with spatio-temporal I<SUB>G</SUB> maxima in either state. For State 1, 
I<SUB>K</SUB> shows 3.5 minute chromospheric oscillations with maxima 
occurring 21 s after I<SUB>G</SUB> maxima implying a 150-210 km 
effective height difference. However, for State 2 the I<SUB>K</SUB> and 
I<SUB>G</SUB> maxima are simultaneous; in this highly magnetized 
environment sites of G-band and K-line emission may be spatially close 
together. 

@--------------------------------------------------------------------
Title:              Effect of Magnetic Fields on Wave Propagation in the 
                    Solar Atmosphere
Authors:            Lawrence, John K.; Cadavid, A. C.; Christian, D. J.
Bibliographic Code: 2011SPD....42.1729L      
    Paper (if ADS pdf and access)    ADS page 

We studied 1 - 24 mHz intensity fluctuations in 3-hour sequences of 
high-cadence, high-resolution, broad-band filtergram images taken by the 
SOT-FG on board the Hinode spacecraft. The observations consist of near 
simultaneous, co-registered G-band (GB), Ca II H-line (HL) intensity 
images, and line-of-sight magnetic images calibrated to Gauss with MDI 
magnetograms. GB is typically used as a proxy for magnetic fields while 
HL is a diagnostic of chromospheric heating. 
We estimate the height z1 of the "magnetic canopy,'' where magnetic 
and gas pressures balance, using potential field extrapolation and the 
Fontenla 2006 model atmosphere. When z1 is above the height of formation 
of both signals, the coherence of the GB and HL oscillations is strong 
for frequencies between 3 mHz and 6 mHz and maximal near 5 mHz, around 
the acoustic cutoff frequency. Near 3 mHz there is no time delay between 
the HL and GB signals indicating a pure standing wave. Above 7 mHz the 
time delay settles near 20 sec indicating an upward propagating acoustic 
wave. When z1 is below the GB and HL heights of formation the coherence 
between the signals drops and has a maximum near 4 mHz. The time delay 
remains zero at 3 mHz, but above 7 mHz it is less than 20 sec and 
decreases with frequency, suggesting that the original acoustic 
fluctuations have undergone mode conversion. 
A similar analysis of ground-based data acquired with the Rapid 
Oscillations in the Solar Atmosphere (ROSA) instrument at the Dunn Solar 
Telescope finds longer time delays of 34 sec when z1 is high and 21 sec 
when z1 is low. This is consistent with the greater effective formation 
height of the ROSA narrowband (1 ) Ca II K-line core compared to 
the more broadband (3 ) H-line in the Hinode data. 

@--------------------------------------------------------------------
Title:              Rapid Oscillations in the Solar Atmosphere: Spectra 
                    and Physical Effects
Authors:            Lawrence, John K.; Christian, D. J.; Cadavid, A. C.;
                    Jess, D. B.; Mathioudakis, M.
Bibliographic Code: 2011SPD....42.1727L
      
    Paper (if ADS pdf and access)    ADS page 

High-frequency fluctuations are observed with the Rapid Oscillations in 
the Solar Atmosphere (ROSA) instrument (Jess et al. 2010, Solar Phys, 
261, 363) at the Dunn Solar Telescope. This can produce simultaneous 
observations in up to six channels, at different heights in the 
photosphere and chromosphere, at an unprecedentedly high cadence of  0.5 
seconds, and at a spatial resolution of 100 km after photometrically 
correct speckle reconstruction. 
Here we concentrate on observations at two levels. The first is in the 
G-band of the CH radical at 4305.5, bandpass 9.2, with 
height of formation z < 250 km at a cadence of 0.525 sec 
corresponding to Nyquist frequency 950 mHz. The second is in the Ca II 
K-line core at 3933.7, bandpass 1.0, with height of 
formation z < 1300 km, and cadence 4.2 sec giving Nyquist frequency 
120 mHz. The data span 53 min, and the maximum field of view is 45 Mm. 
The data were taken on 28 May 2009 in internetwork and network near disk 
center. 
Using both Fourier and Morlet wavelet methods we find evidence in the 
G-band spectra for intensity fluctuations above noise out to frequencies 
f >> 100 mHz. The K-line signal is noisier and is seen only for f 
< 50 mHz. With wavelet techniques we find that G-band spectral power 
with 20 < f < 100 mHz is clearly concentrated in the intergranular 
lanes and especially at the locations of magnetic elements indicated by 
G-band bright points. This wavelet power is highly intermittent in time. 
By cross-correlating the data we find that pulses of high-frequency 
G-band power in the photosphere tend to be followed by increases in 
K-line emission in the chromosphere with a time lag of about 2 min. 

@--------------------------------------------------------------------
Title:              Space - Time Distribution of G-band and Ca ii H-line 
                    Intensity Oscillations in Hinode/SOT - FG 
                    Observations
Authors:            Lawrence, J. K.; Cadavid, A. C.
Bibliographic Code: 2010SoPh..261...35L     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
We study the space - time distributions of intensity fluctuations 
in 2 - 3 hour sequences of multi-spectral, high-resolution, 
high-cadence, broad-band filtergram images of the Sun made by the SOT 
- FG system aboard the Hinode spacecraft. In the frequency range 
5.5< f<8.0 mHz both G-band and Ca ii H-line oscillations are 
suppressed in the presence of magnetic fields, but the suppression 
disappears for f>10 mHz. By looking at G-band frequencies above 10 
mHz we find that the oscillatory power, both at these frequencies and at 
lower frequencies, lies in a mesh pattern with cell scale 2 - 3 
Mm, clearly larger than normal granulation, and with correlation times 
on the order of hours. The mesh pattern lies in the dark lanes between 
stable cells found in time-integrated G-band intensity images. It also 
underlies part of the bright pattern in time-integrated H-line emission. 
This discovery may reflect dynamical constraints on the sizes of rising 
granular convection cells together with the turbulence created in strong 
intercellular downflows. 

@--------------------------------------------------------------------
Title:              Magnetic and Dynamical Properties of Intensity 
                    Oscillations in the Lower Solar Atmosphere
Authors:            Cadavid, A. C.; Lawrence, J. K.
Bibliographic Code: 2009AGUFMSH51A1259C      
    Paper (if ADS pdf and access)    ADS page 

We study 1 - 24 mHz intensity fluctuations in 2-3 hour sequences of 
high-cadence, high-resolution images taken by the SOT-FG on board 
Hinode. The observations consist of near simultaneous, co-registered 
G-Band (GB), Ca II H-Line (HL), and line-of-sight polarization density 
(V/I) images. MDI full-disk and high-resolution magnetograms are used to 
calibrate the V/I to magnetic field in Gauss. This equips us to compare 
fluctuations in magnetic and non-magnetic regions, as well as to study 
recently discovered patterns of enhanced oscillatory power in the 
photosphere and chromosphere. Oscillatory power in non-magnetic regions 
of HL images peaks at ~5 mHz, characteristic of an acoustic signal. As 
magnetic field increases up to ~ 200 G the spectrum is significantly 
diminished in strength, with a shift toward lower frequencies ~ 4 mHz 
starting between 100 - 200 G. In GB images the magnetic spectrum is 
dominant below ~3 mHz, perhaps due to contributions from GB bright 
points, while in non-magnetic regions the acoustic contribution peaks at 
~ 4 mHz. To further investigate these effects we estimate the height of 
the ``magnetic canopy,'' where plasma beta&ap;1, via 
potential field extrapolation from calibrated magnetic images and the 
VAL 3C or more recent model atmospheres. We then segregate the various 
contributions to the power according to whether the signal originates 
above or below the canopy. We have found previously that GB oscillatory 
power at frequencies above 10 mHz lies in a mesh-like pattern with 
characteristic cell scale 2 - 3 Mm, larger than normal granulation, and 
with correlation times on the order of hours. By appropriate segregation 
of image pixels we find that at the sites of enhanced > 10 mHz GB 
spectral power, there is in fact excess spectral power at all 
frequencies, both in GB and HL. 

@--------------------------------------------------------------------
Title:              G-Band Bright Point Oscillations Underlying 
                    Chromospheric Ca II H-Line Emission
Authors:            Lawrence, John K.; Cadavid, A. C.
Bibliographic Code: 2009SPD....40.1004L
      
    Paper (if ADS pdf and access)    ADS page 

We study the spatial distributions of oscillatory power and of emission 
in two sequences of high-cadence, high-resolution images taken by the 
Solar Optical Telescope on board Hinode. The sequences consist of 
simultaneous, co-registered G-Band (GB) and Ca II H-Line (HL) images 
with pixel scale 80 km and fields of view 40 x 40 Mm and 80 x 40 Mm. The 
first sequence has cadence 21 s over  3 hours on 2007 April 14; the 
other has cadence 24 s over  2 hours on 2007 March 30. Both sequences 
include network and internetwork at heliocentric angle  35 degrees. 
The G-Band images were filtered to emphasize the smallest features and 
thus to isolate phenomena connected to the G-Band bright points (GBPs). 
These appear in intergranular lanes and are associated with magnetic 
elements. The filtered G-Band images serve to segment areas in H-Line 
and magnetic images and therefore to explore their connections to the 
GBPs. 
Time averaged Morlet wavelet transforms give smoothed Fourier spectra 
for each spatial location in the data. Averaging over four different 
frequency bands highlights different physical regimes: 
"evolutionary'' timescales (f < 1.2 mHz); evanescent frequencies 
just below the acoustic cutoff (2.6 mHz < f < 4.2 mHz); high 
frequencies just above the cutoff (5.5 mHz <f 10mHz). These last 
frequencies require data cadences < 50 s. Spectral images for the 
filtered GBP data show that the associated spectral power is greatest in 
the evanescent frequency band. The apparent absence of magnetic 
shadowing suggests non-acoustic waves. An image of time-integrated 
H-Line emission shows strong and detailed correlation with the spatial 
distribution of spectral power in the GBP data, thus suggesting a 
possible energy source. 

@--------------------------------------------------------------------
Title:              Phase And Time Lags Between G-band, H-line And 
                    Magnetic Fluctuations In The Photosphere And 
                    Chromosphere
Authors:            Cadavid, Ana Cristina; Lawrence, J.
Bibliographic Code: 2009SPD....40.1003C
      
    Paper (if ADS pdf and access)    ADS page 

We study the oscillatory power in two sequences of high-cadence, 
high-resolution images taken by the SOT on board Hinode. The sequences 
consist of simultaneous, co-registered G-Band (GB), Ca II H-Line (HL), 
and the absolute value of line-of-sight magnetic field (|B|) images, 
with pixel scale 80 km and fields of view 40 x 40 Mm and 80 x 40 Mm. The 
first sequence has cadence 21 s over  3 hours on 2007 April 14; the 
other has cadence 24 s over  2 hours on 2007 March 30. Both sequences 
include network and internetwork at heliocentric angle  35 degrees. 
We investigate phase relations between fluctuations of pairs of the 
three data sets as functions of their common frequencies. The height Z1 
of the "magnetic canopy,'' where plasma beta equal 1, is estimated 
via a potential field extrapolation and the VAL 3C model atmosphere. The 
phase shifts at each frequency are taken as the maxima of normalized 
histograms made by binning the phase shifts for all space-time pixels 
segregated by high or low Z1. We interpret the phase shifts as a 
constant phase shift plus a constant time shift. For Z1 > 1.3 Mm G 
leads H with a constant time lag of  10 sec for frequencies above the 
acoustic cut-off, suggesting propagating acoustic waves. For Z1 < 
1.15 Mm the time lag between the G and H signals is smaller. Both G and 
H lead the |B| fluctuations by a constant phase shift of 100 degrees for 
all Z1. For Z1 < 1.15 G also leads |B| by 31 sec and H trails 
|B| by 61 sec. For Z1 > 1.3 Mm these time lags disappear. 
Thus we can locate an effective "height'' of |B| about 20 km above 
GB and of HL about 40 km above |B|. 

@--------------------------------------------------------------------
Title:              Sources and Propagation of High Frequency Waves in 
                    the Solar Photosphere and Chromosphere
Authors:            Lawrence, John K.; Cadavid, A. C.
Bibliographic Code: 2009SPD....40.1002L
      
    Paper (if ADS pdf and access)    ADS page 

We study the spatial distribution of oscillatory power in two sequences 
of high-cadence, high-resolution images taken by the Solar Optical 
Telescope on board Hinode. The sequences consist of simultaneous, 
co-registered G-Band (GB) and Ca II H-Line (HL) images with pixel scale 
80 km and fields of view 40 x 40 Mm and 80 x 40 Mm. The first sequence 
has cadence 21 s over  3 hours on 2007 April 14; the other has cadence 
24 s over  2 hours on 2007 March 30. Both sequences include network and 
internetwork at heliocentric angle  35 degrees. 
Time averaging of Morlet wavelet transforms gives smoothed Fourier 
spectra for each spatial location in the GB and HL data. We averaged 
over four different frequency bands to highlight different physical 
regimes: "evolutionary'' timescales (f < 1.2 mHz); evanescent 
frequencies just below the acoustic cutoff ( 2.6 mHz < f < 4.2 
mHz); high frequencies just above the cutoff (5.5 mHz <f 10mHz) These 
last frequencies require data cadences < 50 s. 
The evanescent and high frequency spectral images display clear magnetic 
shadowing in both GB and HL channels, though more strongly in the HL. 
Thus the heights at which the GB and HL are formed must both straddle 
the magnetic canopy, with the HL higher up. Interestingly, in the VHF 
band the magnetic shadowing is markedly weakened. The VHF case shows GB 
power in the internetwork that is arranged in the boundary web of a 
cellular pattern with scales  2 - 3 Mm. These are found to coincide with 
the boundaries of stable clusters of granules. These dark boundaries may 
correspond to downflows that control the cell structuring and that could 
be the source of acoustic power. 

@--------------------------------------------------------------------
Title:              Quasi-periodic patterns coupling the Sun, solar wind 
                    and the Earth
Authors:            Ruzmaikin, Alexander; Cadavid, Ana Cristina;
                    Lawrence, John
Bibliographic Code: 2008JASTP..70.2112R
      
    Paper (if ADS pdf and access)    ADS page 

The spectrum of velocity and magnetic fields in the solar wind is 
self-similar (power-law type) in the frequency range greater than 
>1/day indicating well-mixed turbulence. But it loses self-similarity 
for lower frequencies indicating the presence of large-scale patterns, 
which are intermittently generated inside the Sun and propagate from the 
Sun to the Earth. Here we discuss the spatia-temporal characteristics 
and origin of the 1.3-year quasi-periodic pattern found inside the Sun 
by helioseismic methods and detected in the solar wind. To identify and 
characterize this pattern on the Sun we use time series of solar 
magnetic Carrington maps generated at the Wilcox Solar Observatory and 
independent component data analysis. This analysis shows the latitudinal 
distribution of the pattern, its variable frequency and intermittent 
appearance. 

@--------------------------------------------------------------------
Title:              Fine Scale, Rapid Dynamics of the Solar Atmosphere 
                    from Space-Based Versus Ground- Based Observations
Authors:            Lawrence, J. K.; Cadavid, A. C.
Bibliographic Code: 2008AGUFMSH41A1609L
      
    Paper (if ADS pdf and access)    ADS page 

We compare analyses of multi-wavelength, high-cadence sequences of 
high-resolution solar images that are derived from ground-based 
observations and from space-based observations. The original analyses 
aim to show the effects of magnetism on the propagation of wave energy 
from the photosphere into the solar atmosphere. Here we focus on 
differences that arise from the differing circumstances of the data 
acquisition. The ground-based data are a 9 hour sequence of Swedish 
Vacuum Solar Telescope filtergram images made on 1998 May 30 in the 
photospheric G-band and in the chromospheric CaII K-line with 21 s 
cadence. Atmospheric distortion was removed by phase diversity 
reconstruction, and the images were 4 x 4 square averaged to a spatial 
resolution of 0.24 Mm/px. A sequence of line-of-sight magnetograms had 
lesser resolution and longer cadence. The primary space-based data are a 
6 hour sequence at 1 min cadence of Hinode SOT-FG images in G-band and 
CaII H-line and line-of-sight magnetic field, made on 2007 May 2. For 
space-based data phase reconstruction is irrelevant. The spatial scale 
is 0.08 Mm/px but can be averaged to  lower resolutions. The relative 
phases of oscillations in the different data channels and the 
correlations between oscillation periods and spectral intensities show 
significant differences between the space- and ground-based cases. These 
differences may come partly from terrestrial atmospheric fluctuations 
that, in spite of phase reconstruction, act to artificially strengthen 
correlations among the ground-based data channels. For example, the 
photospheric and the chromospheric intensity fluctuations are more 
strongly correlated in the ground data than in the space data. The 
relative phases of oscillations in the three data channels show some 
different dependences on magnetic field strength between the two cases. 
This may be attributable to the higher quality of the available space 
magnetic data. 

@--------------------------------------------------------------------
Title:              Rotational Quasi-Periodicities and the Sun 
                    Heliosphere Connection
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibliographic Code: 2008SoPh..252..179L     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
Mutual quasi-periodicities near the solar-rotation period appear in time 
series based on the Earth's magnetic field, the interplanetary 
magnetic field, and signed solar-magnetic fields. Dominant among these 
is one at 27.030.02 days that has been highlighted by Neugebauer 
et al. ( J. Geophys. Res. 105, 2315, 2000). Extension of their study in 
time and to different data reveals decadal epochs during which the &ap; 
27.0 days, or a &ap; 28.3 days, or other quasi-periods dominate the 
signal. Space-time eigenvalue analyses of time series in 30 solar 
latitude bands, based on synoptic maps of unsigned photospheric fields, 
lead to two maximally independent modes that account for almost 30% of 
the data variance. One mode spans 45 of latitude in the northern 
hemisphere and the other one in the southern. The modes rotate around 
the Sun rigidly, not differentially, suggesting connection with the 
subsurface dynamo. Spectral analyses yield familiar dominant 
quasi-periods 27.040.03 days in the North and at 
28.240.03 days in the South. These are replaced during cycle 23 
by one at 26.450.03 days in the North. The modes show no 
tendency for preferred longitudes separated by &ap; 180. 

@--------------------------------------------------------------------
Title:              Principal Components and Independent Component 
                    Analysis of Solar and Space Data
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A.
Bibliographic Code: 2008SoPh..248..247C     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
Principal components analysis (PCA) and independent component analysis 
(ICA) are used to identify global patterns in solar and space data. PCA 
seeks orthogonal modes of the two-point correlation matrix constructed 
from a data set. It permits the identification of structures that remain 
coherent and correlated or that recur throughout a time series. ICA 
seeks for maximally independent modes and takes into account all order 
correlations of the data. We apply PCA to the interplanetary magnetic 
field polarity near 1 AU and to the 3.25 R <SUB>&sun;</SUB> 
source-surface fields in the solar corona. The rotations of the 
two-sector structures of these systems vary together to high accuracy 
during the active interval of solar cycle 23. We then use PCA and ICA to 
hunt for preferred longitudes in northern hemisphere Carrington maps of 
magnetic fields. 

@--------------------------------------------------------------------
Title:              Search for Persistent Quasi-Periodicities in the 
                    Solar and Interplanetary Magnetic Fields
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibliographic Code: 2007AGUFMSH23A1165L      
    Paper (if ADS pdf and access)    ADS page 

Previous analysis of the radial component of the interplanetary magnetic 
field from 1962 - 1998 has revealed a dominant frequency of 27.03 days 
to 0.02 day accuracy (Neugebauer, et al., 2000). We have repeated and 
extended this analysis with OMNI data from 1963 - 2007 obtained from the 
Coordinated Heliospheric Observations (COHO) database. Over this longer 
data string we find that the 27.03 day Lomb-Scargle periodogram peak is 
reduced while two side peaks near 26.8 days and 27.6 days become almost 
as strong. In the interval 1999-2007 there are two dominant periods near 
26.5 days and 27.2 days. As a solar counterpart to the above analysis we 
have searched for persistent rotation periods near 27 days of global 
patterns of photospheric magnetic fields derived from Wilcox Solar 
Observatory synoptic Carrington rotation maps. Techniques applied 
include, principal components analysis, independent component analysis, 
singular spectrum analysis, wavelet spectral analysis, and complex 
demodulation. We find a variety of quasi- periodicities between 26 and 
29 days that remain coherent for 1 - 2 years. In the southern solar 
hemisphere the strongest periodicity is at 28.2 days, while in the 
northern hemisphere it is around 26.5 days. Neugebauer, M., Smith, 
Smith, E.J., Ruzmaikin, A., Feynman, J., Vaughan, A.H. 2000, J. Geophys. 
Res., 106, A5, 8363. 

@--------------------------------------------------------------------
Title:              Solar Cycle Dependence of Solar Wind 
                    Geoeffectiveness
Authors:            Lawrence, J. K.; Cadavid, A. C.
Bibliographic Code: 2006AGUFMSH24A..04L
      
    Paper (if ADS pdf and access)    ADS page 

We find clear solar cycle dependence of the specific ways in which 
different physical properties of the solar wind (SW) couple to different 
aspects of geomagnetic activity. Geomagnetic activity is described by 
orthogonalized versions Kp, PC/Kp, and Dst/Kp/PC of the familiar 
indices. These represent, respectively, geomagnetic activity measured at 
mid-latitudes, geomagnetic activity measured in the (North) polar region 
and forced to be linearly independent of Kp, and finally geomagnetic 
activity measured at low latitudes and forced to be independent of both 
Kp and PC. Solar wind inputs are hourly averages of the SW plasma beta, 
dynamical pressure, the imposed duskward electric field, and a derived 
parameter related to nonthermally fast SW structures. These were 
measured by the Wind and ACE spacecraft from 1995 through December 2005. 
They were obtained from the OMNI2 data set. We connect these quantities 
using multivatiate factor analysis. During the active phase of Cycle 23 
(1998- 2003) we find that Kp is primarily governed by SW dynamical 
pressure, PC/Kp almost entirely by the imposed electric field, and 
Dst/Kp/PC by the SW plasma beta and by nonthermal structures. This 
result holds separately for the rising and falling phases of the active 
Sun. However, during the preceding quiet Sun period (1995-1997) the 
nonthermal structures were unimportant. Then Dst/Kp/PC was governed by 
the SW plasma beta and dynamical pressure. At the same time, Kp was 
coupled directly to SW pressure and electric field, and negatively to 
plasma beta. 

@--------------------------------------------------------------------
Title:              Quasi-Periodicities, Magnetic Clusters and Solar 
                    Activity
Authors:            Cadavid, A. C.; Lawrence, J. K.; Sandor, C.;
                    Ruzmaikin, A.
Bibliographic Code: 2006AGUFMSH21A0325C
      
    Paper (if ADS pdf and access)    ADS page 

To investigate  quasi-periodicities, 12 hour averages of the radial 
component of the interplanetary magnetic field and the solar wind speed, 
covering ~ 42 (1963-2005) years were analyzed. A Lomb periodogram for 
data up to 1998 showed a dominant period of 27.03 days as fpund in 
earlier results. Including cycle 23, a dominant period of 27.06 days was 
identified. Analysis of the solar cycles independently showed a dominant 
period of 27.03 days in solar cycle 20, but not in the other cycles. To 
investigate the degree of persistency of a particular signal, the 
technique of complex demodulation was applied since it permits the 
determination of continuous changes in time of the amplitude and 
frequency of the signal relative to the test signal. It was found that a 
period of ~27.6 days gave an overall flat phase function in time, while 
other periods < ~0.5 day shorter and longer, with comparable but 
lesser amplitude, come and go. To investigate the solar sources of these 
periods, the method of principal component analysis (PCA) was applied to 
~ 27 years (1976-2003) of synoptic maps obtained with the NSO Kitt Peak 
Vaccum Telescope. Before the analysis, the original synoptic maps were 
shifted relative to the previous maps using the period under 
investigation. Using PCA the Empirical Orthogonal Functions (EOFs) and 
Pricipal Components (PCs) were found for the set of synoptic maps 
rescaled to the rotation rate 27.03 days in 1999-2003. The patterns 
characterized by EOFs 1 and 2 are mostly axisymmetric and PCs 1 and 2 
show solar cycle variability. EOF3  shows only one well-localized 
pattern in the Southern Hemisphere which is markedly non-axisymmetric 
and PC3 has peaks at times when fast CMEs occur. 

@--------------------------------------------------------------------
Title:              Persistent Peridicities in the Solar Wind and 
                    Photospheric Magnetic Field Coherent Structures
Authors:            Cadavid, Ana C.; Lawrence, J. K.; Ruzmaikin, A.
Bibliographic Code: 2006SPD....37.1106C
      
    Paper (if ADS pdf and access)    ADS page 

To investigate persistent periodicities, 12-hour averages of the radial 
component of the interplanetary magnetic field and the solar wind speed, 
covering   42 years (1963-2005), were analyzed. A Lomb periodogram for 
the data up to 1998 showed maximum spectral power at a period of 27.03 
days, as encountered previously by Neugebauer et al. (2000). Including 
cycle 23 shifted the peak to 27.06 days. Analysis of solar cycles 20 - 
23 separately showed a dominant period of 27.03 days in solar cycle 20, 
but not in the other cycles.To investigate the degree of persistency and 
phase coherence of a particular signal, the technique of complex 
demodulation was applied since it permits the determination of 
continuous changes in time of the amplitude and frequency of the signal 
relative to a test signal. It was found that for a reference signal of 
27.03 days, the phase was a flat function of time during the intervals 
1965-1972 and 1995-1997. The phase decreased in time from 1972-1995 and 
increased after 1997. This implies that for the intervals 1972-1995 and 
1997-2005 other periodicities better characterize the data. A period of 
27.6 days gave an overall flat phase function in time, while other 
periods <  0.5 day shorter and longer, with comparable but lesser 
amplitude, come and go.To investigate the solar sources of these 
periods, the methods of principal component analysis (PCA) and 
independent component analysis (ICA) were applied to   27 years 
(1976-2003) of synoptic maps obtained with the NSO Kitt Peak Vacuum 
Telescope. Before the analysis, the original synoptic maps were shifted 
relative to the previous maps using the particular period under 
investigation. PCA and ICA identified 3 modes for the 27.03 reference 
period and 2 modes for the 27.6 period that showed clusters of magnetic 
activity at preferred longitudes. 

@--------------------------------------------------------------------
Title:              Masses and Interactions of q-FERMIONIC Knots
Authors:            Finkelstein, Robert J.; Cadavid, A. C.
Bibliographic Code: 2006IJMPA..21.4269F     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
The q-electroweak theory suggests a description of elementary particles 
as solitons labeled by the irreducible representations of 
SU<SUB>q</SUB>(2). Since knots may also be labeled by the irreducible 
representations of SU<SUB>q</SUB>(2), we study a model of elementary 
particles based on a one-to-one correspondence between the four families 
of fermions (leptons, neutrinos, (-1/3) quarks, (2/3) quarks) and the 
four simplest knots (trefoils). In this model the three particles of 
each family are identified with the ground and first two excited states 
of their common trefoil. Guided by the standard electroweak theory, we 
calculate conditions restricting the masses of the fermions and the 
interactions between them. 
In its present form the model predicts a fourth generation of fermions 
as well as a neutrino spectrum. The same model with q &cong; 1 is 
compatible with the Kobayashi-Maskawa matrix. Depending on the test of 
these predictions, the model may be refined. 

@--------------------------------------------------------------------
Title:              Coherent Structures vs Independent Modes of the 
                    Axisymmetric Magnetic Field Fluctuations
Authors:            Cadavid, A. C.; Lawrence, J. K.; McDonald, D. P.;
                    Ruzmaikin, A.
Bibliographic Code: 2005ASPC..346...91C      
    Paper (if ADS pdf and access)    ADS page 

Quasi periodicities on scales of 1 to 2.5 years have been observed in 
solar, interplanetary and geomagnetic time series. The  relation of  
these signals to 1 and 1.3 yr fluctuations in the solar interior, 
suggest the presence of structures or characteristic modes in the 
magnetic field, generated by the dynamo, that extend into the 
heliosphere. We have applied the methods of principal component analysis 
(PCA) and independent component analysis (ICA) to search for the 
coherent structures (PCA) and independent global modes (ICA) of the 
axisymmetric solar magnetic field. While PCA is effective in identifying 
the coherent modes that describe the 22 yr solar cycle, ICA uncovers the 
independent global modes the with characteristic 1 to 2.5 yr quasi 
periods observed in heliospheric and helioseismic time series. Five 
modes capture the salient properties of the data. Two modes describe the 
polar and high latitude fields, and present  1-1.5 yr quasi 
periodicities. The other three modes correspond to low and mid-latitude 
phenomena and show both 1.3 yr and 1.7 yr variations. 

@--------------------------------------------------------------------
Title:              Solar Wind Interaction and Orthogonal Magnetospheric 
                    Indices
Authors:            Lawrence, J. K.; Cadavid, A. C.
Bibliographic Code: 2005AGUFMSM43A1214L
      
    Paper (if ADS pdf and access)    ADS page 

Multivariate methods can help to untangle connections between indices of 
magnetospheric activity and solar wind (SW) parameters. The data are 
3-hour resolution time series spanning the period 1996 JAN 25 to 2004 
SEP 17. The time series include Kp, the Dst and PC (polar cap) indices 
and an auroral POES index derived from NOAA satellite observations, plus 
OMNI SW data. The Kp index correlates with many other indices of 
magnetospheric activity due to its association with the convection 
electric field (see the survey in Thomsen 2004). We find correlation 
coefficients C(Kp,PC)=0.57, C(Dst,Kp)=-0.44 and C(Dst,PC)=-0.37. POES 
correlations are small. We replace PC with a variable PC/Kp containing 
that part of PC orthogonal to Kp. Likewise we replace Dst with Dst/KpPC, 
orthogonal to both Kp and to PC/Kp. The independent indices behave very 
differently from the original ones. Factor analysis gives five latent 
factor modes relating the terrestrial and SW sets. (1) The only factor 
containing the solar  cycle connects sunspot number fluctuations to POES 
and PC/Kp only. This is the only factor containing POES or PC/Kp, so 
these vary mainly together. (2) Only one factor contains the south IMF, 
and this connects its fluctuations to Kp only. (3) A third factor 
relates strong responses in Dst/KpPC to increases in SW ram pressure, 
temperature and to alpha/proton ratio, an indicator of solar ejecta in 
the SW. (4) A fourth factor relates strong responses in Dst/KpPC to 
increases in excess SW coolness, another indicator of solar ejecta, 
along with drops in mean IMF, SW ram pressure and plasma beta. (5) The 
fifth factor relates increases in Kp to increased mean IMF, SW speed, 
coolness and plasma beta. We present a path analysis calculation 
quantifying the web of causal relations between the SW and the 
independent terrestrial  indices via the intermediate latent factors. 
Thomsen, M.F. 2004, Space Weather, 2, S11004, doi:10.1029/2004SW000089 

@--------------------------------------------------------------------
Title:              Stellar Objects with Infrared Excess in the 
                    \textit{Spitzer Space Telescope} Wide-Area Infrared 
                    Extragalactic Survey (SWIRE)
Authors:            Morales, F. Y.; Werner, M. W.; Padgett, D.;
                    Fajardo-Acosta, S.; Stevens Stern, D.; Chary, R.-R.;
                    Dawson, S.; Dickinson, M.; Stauffer, J. R.;
                    Smith, B.; Walton, S.; Cadavid, A. C.; SWIRE Team;
                    Ana Christina Cadavid Collaboration
Bibliographic Code: 2005AAS...207.6344M
      
    Paper (if ADS pdf and access)    ADS page 

We have identified two new debris disk candidates in the \textit{Spitzer 
Space Telescope} Legacy Project Wide-Area InfraRed Extragalactic Survey 
(SWIRE). We searched two of the six SWIRE photometric survey fields, and 
present 3.6-160 mu m photometry obtained with the Infrared Array 
Camera (IRAC) and the Multiband Imaging Photometer (MIPS) instruments. 
We followed up the candidates with spectro-photometry from 4-36 mu m 
using the Infrared Spectrometer (IRS) low resolution modules. The 
candidates spectral energy distributions (SEDs) were constructed from 
Keck's LRIS optical spectroscopy, \textit{2MASS} J, H, Ks, 
\textit{Spitzer's} IRAC 3.6, 4.5, 5.8, 8.0 mu m bands, and MIPS 24 m 
photometry (70 and 160 mu m when detected). The two candidates, 
Lockman_tile32_1228 and EN1_tile22_11767, were selected by their 24 mu 
m emission above photospheric expected levels, an indicator of the Vega 
phenomenon, or the presence of circumstellar dust at &tilde;120 K. 
Object Lockman_tile32_1228 has 70 and 160 mu m surplus in flux, 
suggesting the presence of cold dust represented by blackbody curves of 
&tilde;65 and &tilde;23 Kelvin. The infrared spectra reveal both sources 
to have infrared excess at wavelengths shorter than 24 mu m as well. 
The shape of Lockman_tile32_1228's SED exhibits interesting features 
from 8 to 20 mu m, possibly due to the composition of the emitting 
material. To confirm these sources are stellar objects, 0.32-0.95 mu m 
optical spectra was obtained via W.M. Keck Observatory's LRIS dual 
spectrometer. LRIS blue and red arm spectroscopy confirms the candidates 
are K-type main sequence stars about 195 and 160 pc away from the Sun. 
At high-galactic latitudes, where interstellar material is scarce, the 
SEDs of these sources illustrate there can exist a diversity of debris 
disk evolutionary states in foreground stars of the Galaxy. 
This work is based on observations made with \textit{Spitzer Space 
Telescope}, which is operated by the Jet Propulsion Laboratory, 
California Institute of Technology, under NASA contract 1407. 

@--------------------------------------------------------------------
Title:              Quasi periodicities in the Fluctuations of the 
                    Axisymmetric Solar Magnetic Field from Independent 
                    Component Analysis
Authors:            McDonald, D. P.; Cadavid, A. C.; Lawrence, J. K.;
                    Ruzmaikin, A.
Bibliographic Code: 2005AGUSMSP43B..05M
      
    Paper (if ADS pdf and access)    ADS page 

Observed solar, interplanetary and geomagnetic time series contain quasi 
periodicities on the order of 1 to 2.5 years.  The further discovery of 
1.3 year fluctuations in helioseismic observations suggests that a 
variety of signals may be related to the underlying dynamo in the Sun. 
We have applied the methods of principal component analysis (PCA) and 
independent component analysis (ICA) to search for the coherent 
structures (PCA) and independent global modes (ICA) of the axisymmetric 
solar magnetic field. While PCA was shown to be  effective in 
identifying the coherent modes that describe the 22 yr solar cycle, ICA 
uncovers the independent global modes  with characteristic 1 to 2.5 yr 
quasi periods observed in heliospheric and helioseismic time series.  We 
found that five modes effectively describe the data in both spatial and 
temporal domains.  Two modes describe the polar and high latitude 
fields, and present 1-1.5 year quasi periodicities.  The other three 
modes correspond to low and mid-latitude phenomena and show both 1.3 
year and 1.7 year variations.  By comparing the characteristic 
timescales, dates of occurrence and heliocentric latitudes of these 
modes, we connect them to their manifestations in heliospheric time 
series. 

@--------------------------------------------------------------------
Title:              Coherent Structures and Rotation Rates in Coronal 
                    Activity, from Principal Component Analysis
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A.
Bibliographic Code: 2005AGUSMSP21B..07C
      
    Paper (if ADS pdf and access)    ADS page 

Principal component analysis (PCA) offers a way to extract those 
structures that remain spatially coherent throughout a time series. We 
apply this method to a ~ 28 year time series of Wilcox Solar Observatory 
Carrington rotation maps (CR) of the 3.25 R coronal source surface field 
obtained via a potential field extrapolation. We find that over 99% of 
the variance is contained in the first eight modes. Mode 1, carrying 
81.5% of the variance, and modes 2 and 3 containing 13% of the variance, 
have "dipole" structures. Modes 4-8, with a "quadruple" structure, 
contain 4.5% of the variance. The principal components (PCs) give the 
time dependence of the modes. We combine the PCs of  modes 2 and 3 to 
get the amplitude and phase of a structure that behaves essentially as a 
dipole in the equatorial plane. During activity minima the structure is 
relatively weak and rotates at the 27.275 day Carrington rate. During 
the active periods of cycles 21 and 22 the amplitude is large and highly 
intermittent, and the dipole rotates more rapidly than the Carrington 
rate with a synodic period of 26.6 days. During cycle 23, however, the 
dipole moves backward in Carrington longitude with a synodic period of 
27.8 days. The average of these is ~ 27.0 days, though this is actually 
realized only sporadically. The phase changes that occur at shorter time 
scales and that coincide with intermittent changes in the dipole 
amplitude seem to represent essentially random effects of the passage of 
the magnetic field through the convection zone. While the lower modes 
tend to lock the hemispheres together the higher modes present separate 
Northern and Southern hemisphere quadrupole-type patterns that drift in 
Carrington longitude similarly to the equatorial dipole. Over some 
periods the drift in each hemisphere closely tracks the other over a 
wide range of timescales. However, there are large, decadal-scale 
excursions in which first one hemisphere leads in phase by 3 or 4 
rotations and then the other leads by a similar amount. 

@--------------------------------------------------------------------
Title:              Magnetic Topology and Wave Propagation in the Solar 
                    Atmosphere
Authors:            Lawrence, J. K.; Cadavid, A. C.; McIntosh, S. W.;
                    Berger, T. E.
Bibliographic Code: 2005AGUSMSH13C..01L
      
    Paper (if ADS pdf and access)    ADS page 

We analyze a 9 hr sequence of simultaneous, high resolution, 21 s 
cadence SVST G-band and K-line solar filtergrams plus magnetograms of 
lower cadence and resolution. The data include both network and 
internetwork areas (Berger and Title 2001, Cadavid, et al. 2003, 
Lawrence, et al. 2003). Time series of the G-band and K-line data are 
compared after filtering by a Morlet wavelet transform of period 2.5 
min. On the average, the K-line signal is delayed by several seconds 
after the G-band signal Delta T = 8.6  0.1 s for weak (|BZ| 
< 50 G) magnetic field in internetwork but Delta T = 7.2  
0.1 s for weak field in an area including network. The internetwork has 
no strong fields, but in network (|BZ| > 80 G) the mean delay time 
drops to Delta T = 3.4  0.3 s. This is consistent with results 
by McIntosh, Fleck and Tarbell (2004) using TRACE 1600 and 
1700 UV image series. Our principal result is that the time delay 
is greater in the internetwork than in the network by 1.4  0.1 
s, even for the same local magnetic field strength. This suggests that 
the difference must be an effect of the field topology. Spatial maps of 
time delays, in comparison to maps of such topological quantities as the 
height in the solar atmosphere at which the plasma beta = 1, offer 
additional details of the relationship between wave propagation and the 
magnetic fields in the solar atmosphere. This work was supported in part 
by grants NSF-ATM 9987305 and NASA-NAG5-10880. The SVST is operated by 
the Swedish Royal Academy of Sciences at the Spanish Observatorio del 
Roque de los Muchachos of the Instituto de Astrofisica de Canarias. 
Berger, T.E. and Title, A.M. 2001, ApJ, 553, 449. Cadavid, A.C., et al. 
2003, ApJ, 586, 1409. Lawrence, J.K., et al. 2003, ApJ, 597, 1178. 
McIntosh, S.W., Fleck, B. and Tarbell, T.D. 2004, ApJ, 609, L95. 

@--------------------------------------------------------------------
Title:              Independent Global Modes of Solar Magnetic Field 
                    Fluctuations
Authors:            Cadavid, A. C.; Lawrence, J. K.; McDonald, D. P.;
                    Ruzmaikin, A.
Bibliographic Code: 2005SoPh..226..359C
      
    Paper (if ADS pdf and access)    ADS page 

Observed solar, interplanetary and geomagnetic time series contain quasi 
periodicities on scales of 1 2.5 years. The further discovery of 1.3 
year fluctuations in helioseismic observations suggests that a variety 
of signals may be related to the underlying dynamo in the Sun. We use 
independent component analysis to study the temporal and spatial 
variations of a few statistically independent global modes of the 
axisymmetric solar magnetic field over a period of 25 years. Five modes 
capture the salient properties of the data. Two modes describe the polar 
and high latitude fields, and present 1 1.5 year quasi periodicities. 
The other three modes correspond to low and mid-latitude phenomena and 
show both 1.3 and 1.7-year variations. By comparing the characteristic 
time scales, dates of occurrence and heliocentric latitudes of these 
modes, we connect them to their manifestations in heliospheric time 
series. 

@--------------------------------------------------------------------
Title:              Principal Component Analysis of the Solar Magnetic 
                    Field I: The Axisymmetric Field at the Photosphere
Authors:            Lawrence, John K.; Cadavid, Ana;
                    Ruzmaikin, Alexander
Bibliographic Code: 2004SoPh..225....1L
      
    Paper (if ADS pdf and access)    ADS page 

A principal component analysis, or proper orthogonal decomposition, of 
the axisymmetric magnetic field at the photosphere is carried out to 
find an optimal representation of the observed solar cycle. The 22-year 
periodic field requires just two modes. NSO Kitt Peak synoptic maps for 
Carrington rotations 1664 2007 were reduced by taking both the mean and 
the median field over longitude to produce two sequences of functions of 
sine latitude spanning 25.7 years. The lowest modes of each are 
determined by the polar fields. The mean field is most efficient at 
representing the periodic field, but the median field is more efficient 
at representing the evolution of the diffuse field patterns. 

@--------------------------------------------------------------------
Title:              Principal Component Analysis of the Latitudinal and 
                    Longitudinal Structure of the Photospheric Magnetic 
                    Cycle
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibliographic Code: 2004AAS...204.3708L
      
    Paper (if ADS pdf and access)    ADS page 

We average magnetic fields in NSO synoptic maps over longitude and bin 
the result by sin(latitude). Also, we average over a band of latitudes 
and bin by longitude. A time stack of one-dimensional latitude "images" 
resembles the Maunder butterfly diagram. Time stacks of longitude 
"images" can be re-mapped to arbitrary rotation periods. 
Principal component analysis recombines images in a stack into mutually 
orthogonal "empirical orthogonal functions" (EOFs). The EOFs are ordered 
by how well each correlates with the full set of images. The principal 
components (PCs) give the evolution of each EOF as a function of any 
ordering parameter, such as time. The original data can be wholly or 
partially reconstructed from subsets of the EOFs and their PCs. 
Our latitudinal EOFs have a few leaders whose PCs show both the 
11/22-year cycle and repeating substructure. Following are EOFs whose 
PCs show the cycle but no repeated substructure. Next are EOFs with 
small scale structure independent of the cycle. The least correlated 
EOFs contain high latitude, mostly unipolar fields. We suggest 
associating these four subsets of the EOFs with, respectively, global 
dynamo toroidal fields, turbulently disordered structures fed by the 
toroidal fields, a possible local surface dynamo process, and a global 
poloidal component. 
We also studied a stack of longitudinal images of fields that were 
averaged over latitude between N25 and N35 degrees. Two especially 
active longitudes 180 degrees apart rotate with a period of 27.8 days. 
Structure at these longitudes dominates the leading EOFs. The 
corresponding PCs are active over the whole span of the data. 
This work was supported by NASA Grant NAG5-10880. NSO/Kitt Peak data 
used here are produced cooperatively by NSF/NOAO, NASA/GSFC, and 
NOAA/SEL. 

@--------------------------------------------------------------------
Title:              Two-dimensional Empirical Orthogonal Functions of 
                    the Photospheric Magnetic Cycle
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A.
Bibliographic Code: 2004AAS...204.3707C
      
    Paper (if ADS pdf and access)    ADS page 

We carried out a principal component analysis (PCA) on sequences of NSO 
magnetic flux synoptic maps by Carrington rotation. Two data sets were 
investigated: (i) a sequence of 364 images from Carrington rotation 1625 
to 2007, with image size 360 x 180 pixels (1 degree/pixel in longitude 
and sin(latitude)*90 in latitude for both hemispheres); (ii) a sequence 
of 79 higher resolution maps of size 1800 x 900 pixels starting at 
Carrington rotation 1913. The PCA of a time series yields an eigenvalue 
spectrum, the corresponding eigenfunctions (modes or "empirical 
orthogonal functions" (EOFs)), and the principal components which 
describe the time evolution of the modes. The dominant EOFs are 
associated with those structures that remain spatially coherent 
throughout intervals of the time series, and correspond to the functions 
with the highest eigenvalues. If the eigenvalue spectrum is dominated by 
only a few large members, then the corresponding few EOFs will mainly 
characterize the data. The rest will contain transient fluctuations. We 
apply the technique to the two dimensional maps and determine which EOFs 
dominate during different times of the solar cycle. We find that the 
dominant modes are associated with the active part of the cycle as 
expected, while the weaker modes characterize the quiet periods. The 
increasing and declining phases are associated with modes of 
intermediate eigenvalues. We reconstruct the time series by projecting 
onto the three classes of modes and investigate the probability 
distribution function (PDF) of "projected" magnetic flux. We compare 
these results to the PDFs obtained from artificial data generated by 
dynamo models. This work was supported in part by Grant NASA-NAG5-10880. 
NSO/Kitt Peak data used here are produced cooperatively by NSF/NOAO, 
NASA/GSFC, and NOAA/SEL. 

@--------------------------------------------------------------------
Title:              A simple model of solar variability influence on 
                    climate
Authors:            Ruzmaikin, Alexander; Lawrence, John K.;
                    Cadavid, Ana Cristina
Bibliographic Code: 2004AdSpR..34..349R
      
    Paper (if ADS pdf and access)    ADS page 

We present a simple dynamic model of solar variability influence on 
climate, which is truncated from the stratospheric wave-zonal flow 
interaction dynamics over a beta-plane. The model consists of three 
ordinary differential equations controlled by two parameters: the 
initial amplitude of planetary waves and the vertical gradient of the 
zonal wind. The changes associated with the solar UV variability, as 
well as with seasonal variations, are introduced as periodic modulations 
of the zonal wind gradient. Influence of the Quasi-Biennial Oscillation 
is included as a periodic change of the width of the latitudinal extent 
of the beta-plane. The major climate response to these changes is seen 
through modulation of the number of cold and warm winters. 

@--------------------------------------------------------------------
Title:              Influence of Photospheric Magnetic Fields and 
                    Dynamics on Chromospheric K-Line Emission
Authors:            Lawrence, J. K.; Cadavid, A. C.; Miccolis, D.;
                    Berger, T. E.; Ruzmaikin, A.
Bibliographic Code: 2003ApJ...597.1178L
      
    Paper (if ADS pdf and access)    ADS page 

We analyze a 9 hr sequence of simultaneous, high-resolution, 
high-cadence G-band and K-line solar filtergrams plus magnetograms of 
lower cadence and resolution. Images include both network and 
internetwork. The magnetic and filtergram intensities, their 
fluctuations, and relative phases change with progressive strengthening 
of local magnetic field. At increased flux levels, sudden photospheric 
downflows create long-lived magnetic elements. For weak magnetic fields 
the K-line and G-band intensities include an oscillatory component with 
period 4 minutes. For stronger fields, the K-line period shifts to 5 
minutes, while the G-band fluctuations fade due to dissociation of their 
source, the CH radical. These K-line and G-band fluctuations, whose 
periods are longer than the acoustic cutoff, are coherent and in phase. 
They also are coherent with fluctuations of the magnetic field. 
Weak-field magnetic fluctuations lead the intensity fluctuations by a 
phase shift of 90. Strong-field magnetic fluctuations trail the 
intensities by 100. These are interpreted as standing waves in the 
photosphere and low chromosphere. Another class of G-band fluctuations, 
with periods shorter than the acoustic cutoff, is associated both with 
stronger magnetic fields and with enhanced K-line emission with 
fluctuations longer than the cutoff period. This suggests waves excited 
by rapid photospheric perturbations and propagating up along magnetic 
flux tubes. 

@--------------------------------------------------------------------
Title:              Influence of Photospheric Magnetism and Dynamics on 
                    Chromospheric K-line Emission
Authors:            Lawrence, J. K.; Cadavid, A. C.; Miccolis, D.;
                    Berger, T. E.; Ruzmaikin, A.
Bibliographic Code: 2003SPD....34.0704L
      
    Paper (if ADS pdf and access)    ADS page 

We analyze a unique 9 hr sequence of near simultaneous, high resolution 
and high cadence G-band and K-line SVST solar filtergrams together with 
magnetograms of lower cadence and resolution. We focus on a region of 
the solar surface that includes both internetwork and network. We 
examine how the (temperature minimum/chromospheric) CaII K-line and 
(photospheric) G-band intensities, their temporal fluctuations and their 
coherence and phase relations, with each other and with magnetic 
fluctuations, change as we progress from weak magnetic fields 
(internetwork) to intermediate and strong fields (network). 
As the background level of flux is increased, sudden photospheric 
downflow events can create long-lived, compact (i.e. network) magnetic 
elements. For weak magnetic fields the K-line and G-band intensity 
signals show an oscillatory component with period centered on 4 min. As 
we pass to strong fields, the K-line signal shifts to a 5 min period 
while the G-band signal fades, presumably due to dissociation of the CH 
radical. The K-line and G-band signals are coherent and nearly in-phase. 
They are both coherent with fluctuations of the magnetic field. For weak 
field the magnetic signal leads the intensity signals by 90<SUP>o</SUP> 
in phase. For intermediate and strong fields the magnetic signal trails 
the intensities by 110<SUP>o</SUP>. We interpret this as a transition 
from acoustic standing waves with weak, passive magnetic field to a slow 
mode trapped magnetoacoustic wave. For intermediate magnetic field we 
find, in addition to the coherent waves, that G-band fluctuations at 
frequencies above the acoustic cutoff (period < 3.5 min) are 
associated with magnetic fields and with K-line emission at periods > 
3.5 min. This suggests the presence of flux tube waves excited by rapid 
photospheric perturbations. 
This work was supported by grants NSF-ATM 9987305 and NASA-NAG5-10880. 
The SVST is operated by the Swedish Royal Academy of Sciences at the 
Spanish Observatorio del Roque de los Muchachos of the Instituto de 
Astrofisica de Canarias. 

@--------------------------------------------------------------------
Title:              Photospheric Sources of Chromospheric Dynamics in 
                    the Internetwork
Authors:            Cadavid, A. C.; Lawrence, J. K.; Berger, T. E.;
                    Ruzmaikin, A.
Bibliographic Code: 2003SPD....34.0703C
      
    Paper (if ADS pdf and access)    ADS page 

We analyze a unique 9 hr sequence of near simultaneous, high resolution 
and high cadence G-band and K-line solar filtergrams together with 
magnetograms of lower cadence and resolution, taken with the SVST. We 
investigate an internetwork region characterized by magnetic fields with 
strength < 150 Gauss and focus on the phenomena surrounding discrete 
photospheric darkening ``events'' in G-band intensities. 72 % of the 
darkenings are followed after 2 min by K-line brightenings. In the 
remaining cases the darkenings are instead preceded by K-line 
brightenings 2 min earlier. In both cases the preceding and following 
G-band minima are each associated with transient magnetic enhancements, 
and thus, presumably, photospheric inflows followed by outflows. The 
magnetic field appears to have no role in coupling the photospheric 
phenomena to the chromosphere, and acts as a passive tracer of 
horizontal photospheric flows that converge on the photospheric 
darkening events and then rebound. The timing and coupling of the 
photospheric darkenings and chromospheric brightenings appear to be 
regulated by a pre-existing 4 min oscillation of the solar atmosphere. 
Other oscillations with periods in the range 1-8 min also are present, 
and in general the wave power is doubled at the time of an event. At 
short periods temporal structure is resolved. Our results favor an 
acoustic source for enhanced amplitudes of K-line intensity 
oscillations. 

@--------------------------------------------------------------------
Title:              Photospheric Sources and Brightening of the 
                    Internetwork Chromosphere
Authors:            Cadavid, A. C.; Lawrence, J. K.; Berger, T. E.;
                    Ruzmaikin, A.
Bibliographic Code: 2003ApJ...586.1409C
      
    Paper (if ADS pdf and access)    ADS page 

We analyze a unique 9 hr sequence of near-simultaneous, high-resolution 
and high-cadence G-band and K-line solar filtergrams, together with 
magnetograms of lower cadence and resolution. Our focus is on the 
phenomena surrounding discrete photospheric darkening ``events'' in 
internetwork G-band intensities. 72% of the darkenings are followed 
after 2 minutes by K-line brightenings. In the remaining cases, the 
darkenings are instead preceded by K-line brightenings 2 minutes 
earlier. Equivalent results are found when reference is shifted to 
K-line brightening events, although these two sets overlap by no more 
than 15%. The timing and coupling of the photospheric darkenings and 
chromospheric brightenings appear to be regulated by a preexisting 4 
minute oscillation of the solar atmosphere. Other oscillations with 
periods in the range 1-8 minutes also are present, and in general the 
wave power is doubled at the time of an event. Our results favor an 
acoustic source for enhanced amplitudes of K-line intensity 
oscillations. The magnetic field acts as a passive tracer of horizontal 
photospheric flows that converge on the photospheric darkening events 
and then rebound. 

@--------------------------------------------------------------------
Title:              High Resolution Spatio-Temporal Study of 
                    Photospheric and Chromospheric Energetics
Authors:            Cadavid, A. C.; Lawrence, J. K.; Berger, T. E.
Bibliographic Code: 2002AAS...200.3809C
      
    Paper (if ADS pdf and access)    ADS page 

We study the photosphere/chromosphere energetic connection using a nine 
hour sequence of SVST images obtained May 30, 1998. The data consist of 
co-spatial, nearly simultaneous filtergrams of G-band (4305  ), 
Ca II K (3934  ), two (6563 ) Halpha channels offset by 
0.35  and 0.7  , and Fe I (6302 ) magnetograms. The 
cadence of the G-band and Ca K observations is ~ 30 s; that of the other 
images is ~ 2 min. The pixel scale is 0.06 Mm and field of view 48 X 48 
Mm on the Sun. The filtergram resolution is > 0.2 Mm; that of the 
magnetograms > 0.3 Mm with single magnetogram sensitivity < 150 G. 
We have co-registered the images to 1 or 2 pixel accuracy. The number 
distribution of Ca brightenings and of localized changes in magnetic 
field strength, measured in standard deviations (sigma ) from the 
image means, present three different characteristic regimes; that of the 
magnetic ``free energy'' (a derived measure based on the local variance 
of magnetic field) presents two. Ca brightenings below 3sigma show a 
weak but significant correlation with local magnetic field and free 
energy. At 3sigma the strength of the correlation abruptly increases. 
Above 5sigma no correlation is apparent, but large magnetic field 
values appear. Using a mask to remove the network areas, the weakest 
brightenings (<1.5 sigma ) show anti-correlation with the magnetic 
field. For 1.5 sigma to 4.5 sigma there is no correlation. For 
selected network examples we follow the time evolution in all observed 
lines. We find cases in which an increase and then relaxation in the 
magnetic free energy just precedes a local rise in Ca emission followed 
by a drop to a lower background level than initially. Work supported in 
part by NSF-ATM-9987305 and NASA-NAG5-10880. 

@--------------------------------------------------------------------
Title:              Mesogranulation from Principal Component Analysis of 
                    SVST Photospheric Continuum Images
Authors:            Bell, E.; Cadavid, A. C.; Lawrence, J. K.;
                    Berger, T. E.
Bibliographic Code: 2002AAS...200.3805B
      
    Paper (if ADS pdf and access)    ADS page 

We analyze a sequence of 279 images of the photosphere made with the 
Swedish Vacuum Solar Telescope on 1997 June 11. The sequence spans 3 hr 
with cadence 38 s. The images were taken in continuum near 4364 , 
and underwent phase diversity reconstruction. Resolution is ~ 0.2 Mm and 
field of view 32 X 32 Mm. We carried out a principal component analysis 
on sequences of 15 images spaced 6 min apart and covering 1.5 hr. The 15 
X 15 correlation matrix of each such set of images was diagonalized, 
giving 15 eigenimages which are linear combinations of the original 15. 
The eigenimage corresponding to the largest eigenvalue is the linear 
combination that best resembles the original set as a whole; those with 
smaller and smaller eigenvalues resemble the overall set less and less 
well. Fourier spectra of the eigenimages were calculated separately for 
several sequences and then averaged together to reduce uncertainties. 
Fourier analysis of the leading eigenimage reveals structure at two 
scales: one for lambda =1/nu ~ 1.5 Mm corresponding to granulation 
and another for lambda ~ 4.5 Mm. Because of their scale and because 
the time span of the sets lies between the lifetimes of granules and 
mesogranules, we interpret the latter as mesogranules. The subsequent 
eigenimages do not show the larger structure, but show the granular peak 
at successively smaller scales. This indicates a spatio-temporal scaling 
of the granulation with shorter lifetimes for smaller features. For 
comparison purposes, simulated granulation images (Cattaneo, Lenz and 
Weiss 2001) were similarly analyzed and give similar results. Work 
supported in part by grants NSF-ATM-9987305, NASA-NAG5-10880 and the 
NASA CSUN/JPL PAIR Program. F. Cattaneo, D. Lenz and N. Weiss 2001, ApJ, 
563, L91. 

@--------------------------------------------------------------------
Title:              Observations of the Structure of small scale 
                    photospheric fields
Authors:            Lawrence, J.; Cadavid, A.; Ruzmaikin, A.; Berger, T.
Bibliographic Code: 2002ocnd.confE..26L
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              A simple model of solar variability influence on 
                    climate.
Authors:            Ruzmaikin, A.; Lawrence, J.; Cadavid, A.
Bibliographic Code: 2002cosp...34E.336R
      
    Paper (if ADS pdf and access)    ADS page 

We introduce and study a simple dynamic model of solar influence on 
climate. The model is truncated from the stratospheric wave-zonal flow 
interaction model suggested by Holton and Mass (1976). Our model 
consists of three ordinary differential equations controlled by two 
parameters: the initial amplitude of planetary waves and the vertical 
gradient of the zonal wind. The changes associated with seasonal 
variations and with the solar variability are introduced as periodic 
modulations of the zonal wind gradient. The major atmospheric response 
to these changes is seen through modulation of the number of cold and 
warm winters. 

@--------------------------------------------------------------------
Title:              Alfvn Wave Generation by Multifractal Solar 
                    Magnetic Fields
Authors:            Lawrence, J.; Cadavid, A.; Ruzmaikin, A.
Bibliographic Code: 2001AGUFMNG21A0402L
      
    Paper (if ADS pdf and access)    ADS page 

The high speed particles and magnetic fields of the solar wind form an 
important part of the earth's space environment. However, the energy 
supply driving this wind is not fully understood. The heating mechanism 
seems clearly to be rooted in the turbulent plasma of the solar 
convection zone. However, the amplitude and frequency spectrum of 
Alfvn waves emitted from the top of the photosphere are strongly 
dependent on the magnetic field strength and configuration [1]. Aside 
from the amplitude, the suitability of the Alfvn waves for 
accelerating the solar wind is strongly dependent on their frequency 
range. One estimate [2] requires frequencies 0.01 Hz <nu < 10 
kHz. Waves below 0.01 Hz are reflected. We have found that solar surface 
fields have an intermittent structure [3], pointing to generation by a 
multiplicative cascade process [4]. Projection to smaller scales of this 
observed symmetry allows us to propose a realistic photospheric magnetic 
flux distribution. This can be combined with a Kolmogorov photospheric 
velocity field [5] and the notion of flux tube impedance matching [1] 
for generation of Alfvn and fast mode MHD waves. The 
Alfvn flux depends on the cube of the magnetic field strength; 
for an assumed mean field of 10 G, and efficient wave excitation, we 
find an output flux ~ 1.7 x 10<SUP>5</SUP> ergs cm<SUP>-2</SUP> 
s<SUP>-1</SUP> essentially all of which is produced at periods between 
30 s and 80 s. Above a strong cutoff near nu < 0.01 Hz, the flux 
frequency spectrum is a power law arpropto nu <SUP>{-beta 
</SUP> } with beta = 3.51 +/- 0.08. Such waves could contribute 
significantly to solar wind acceleration. [1] Parker, E.N. 1992, in E. 
Marsch and R. Schwenn (eds.), Solar Wind Seven (COSPAR Colloquia Series, 
Vol. 3), Pergamon Press, Oxford, p. 79. [2] Mckenzie, J.F., 
Banaszkiewicz, M. and Axford, W.I. 1995, Astron. Astrophys., 303, L45. 
[3] Lawrence, J.K., Ruzmaikin, A.A. and Cadavid, A.C. 1993, Astrophys. 
J., 417, 805. [4] Lawrence, J.K., Cadavid, A.C. and Ruzmaikin, A.A. 
1995, Phys. Rev. E, 51, 316. [5] Lawrence, J.K., Cadavid, A.C., 
Ruzmaikin, A. and Berger, T.E. 2001, Phys. Rev. Lett., 86, 5894. 

@--------------------------------------------------------------------
Title:              Nonlinear spinor in a Kerr-Schild background
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 2001JMP....42.4419C
      
    Paper (if ADS pdf and access)    ADS page 

We study the nonlinear spinor field in a Kerr-Schild background by first 
looking for solitonic solutions in the absence of rotation, given that 
in the special relativistic limit there are solitonic solutions in this 
approximation. Since for the scalar field problem at least two 
independent radial functions are needed for the solitonic solutions to 
exist, we introduce a dilation field by deforming the Kerr-Schild metric 
by a Weyl factor. We find that for the parameter space studied there are 
no solitonic solutions in the spherically symmetric approximation. While 
in the present work we have studied the spinor field, we also had in 
mind a corresponding study of a scalar field in the same background 
where it may be of interest for describing a rotating stellar soliton. 
The proposed strategy in both cases begins by looking for solitonic 
solutions in the absence of rotation and then continues by 
perturbatively correcting for the rotation required by the angular 
dependence of the Kerr background. The strategy appears to be 
unsuccessful. 

@--------------------------------------------------------------------
Title:              Mesogranulation and Turbulence in Photospheric Flows
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibliographic Code: 2001SoPh..202...27L     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
Below the scale of supergranules we find that cellular flows are present 
in the solar photosphere at two distinct size scales, approximately 2 Mm 
and 4 Mm, with distinct characteristic times. Simultaneously present in 
the flow is a non-cellular component, with turbulent scaling properties 
and containing 30% of the flow energy. These results are obtained by 
means of wavelet spectral analysis and modeling of vertical photospheric 
motions in a 2-hour sequence of 120 SOHO/MDI, high-resolution, Doppler 
images near disk center. The wavelets permit detection of specific local 
flow patterns corresponding to convection cells. 

@--------------------------------------------------------------------
Title:              Spatiotemporal Scaling of Solar Surface Flows
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.;
                    Berger, T. E.
Bibliographic Code: 2001PhRvL..86.5894L     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
The sun provides an excellent natural laboratory for nonlinear 
phenomena. We use motions of magnetic bright points on the solar 
surface, at the smallest scales yet observed, to study the small scale 
dynamics of the photospheric plasma. The paths of the bright points are 
analyzed within a continuous time random walk framework. Their spatial 
and temporal scaling suggests that the observed motions are the walks of 
imperfectly correlated tracers on a turbulent fluid flow in the lanes 
between granular convection cells. 

@--------------------------------------------------------------------
Title:              Mesogranulation and Turbulence in Photospheric Flows
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibliographic Code: 2001AGUSM..SP41C02L      
    Paper (if ADS pdf and access)    ADS page 

Cellular flows are present in the solar photosphere at two distinct size 
scales, 2 Mm and 4 Mm, with distinct characteristic times. 
Simultaneously present in the flow is a non-cellular component, with 
turbulent scaling properties between 1 Mm and 64 Mm, and containing 30 % 
of the flow energy. These results are obtained by means of wavelet 
spectral analysis and modeling of vertical photospheric motions in a 
2-hour sequence of 120 SOHO/MDI, high resolution, Doppler images near 
disk center. The wavelets permit detection of specific local flow 
patterns corresponding to convection cells. Standard spectral techniques 
have difficulty resolving mesogranules for three basic reasons: (1) the 
mesogranules are near in scale to granules and weaker in velocity and 
(2) they are hidden by overlying turbulence because (3) global basis 
functions, such as Fourier waves or spherical harmonics, do not allow 
attention to be paid to the local topologies that label cellular flows. 

@--------------------------------------------------------------------
Title:              Sensitivity of Nonlinear Atmospheric Circulation 
                    Models to Variable Forcing
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibliographic Code: 2001AGUSM..NG52B03L
      
    Paper (if ADS pdf and access)    ADS page 

A three-variable, nonlinear dynamical system was proposed by Lorenz as 
an extremely simple model of the general circulation of the atmosphere. 
This is driven by a longitudinal as well as a latitudinal external 
forcing. In the presence of a strong annual cycle in the forcing, 
numerical exploration reveals a variety of multi-year climate states 
with different mean westerly flows. In some areas of the space of 
external forcing parameters, the different states are closely 
interleaved, at scales less than 0.01 %. Thus, even tiny cyclic or 
secular changes in the forcing can produce large effects in the 
circulation. Here we extend the analysis to a broader general 
circulation model of Saltzman, et al., which includes the Lorenz 
circulation model as a particular case. Results are qualitatively the 
same as before. Bifurcation properties of the models are discussed. 

@--------------------------------------------------------------------
Title:              The response of atmospheric circulation to weak 
                    solar forcing
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A.
Bibliographic Code: 2000JGR...10524839L
      
    Paper (if ADS pdf and access)    ADS page 

We study the effect of variable external forcing on a dynamical system 
proposed by Lorenz as "perhaps the simplest possible `general 
circulation' model" of the atmosphere. When a strong annual cycle is 
included, numerical exploration reveals the existence of a variety of 
multiyear climate states, which fall into two basic types. In the space 
of external forcing parameters, the different kinds of climate state are 
interleaved in an intricate pattern at scales <=0.01%. Since this is 
below the &tilde;0.1% level of observed solar cycle irradiance 
variability, then the model climate state can be modulated by the solar 
variability. If the solar cycle is accompanied by a steady drift in 
forcing, it can produce periodic modulation that appears, disappears, 
and even reverses its phase. A parametric drift by itself produces 
intervals of steady, but sometimes differing, climates punctuated by 
intermittent bursts of variability. Different forcing parameters for the 
Northern and Southern Hemispheres produce different responses to 
variable forcing. We test the stability of the results under the 
addition of noise and changes of system parameters. 

@--------------------------------------------------------------------
Title:              Response to Weak Solar Forcing in a General 
                    Circulation Model of the Atmosphere
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibliographic Code: 2000SPD....3102117C
      
    Paper (if ADS pdf and access)    ADS page 

We study the effect of variable external forcing on a dynamical system 
proposed by Lorenz as a simple general circulation model of the 
atmosphere. When a strong annual cycle is included, numerical 
exploration reveals the existence of a variety of multi-year climate 
states, which fall into two basic types. In the space of external 
forcing parameters, the different kinds of climate state are interleaved 
in an intricate pattern at scales < 0.01. This is below the ~ 0.1 
level of observed solar cycle irradiance variability which can thus 
modulate the model climate state. If the solar cycle is accompanied by a 
steady drift in forcing, it can produce periodic modulation which 
appears, disappears and even reverses its phase. A parametric drift by 
itself produces intervals of steady, but sometimes differing, climates 
punctuated by intermittent bursts of variability. Different forcing 
parameters for the Northern and Southern Hemispheres produce different 
responses to variable forcing. 

@--------------------------------------------------------------------
Title:              Response to weak solar forcing in a general 
                    circulation model of the atmosphere.
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibliographic Code: 2000BAAS...32R.832C
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              Random Walks of Magnetic Bright Points and Coronal 
                    Loop Heating
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibliographic Code: 2000AAS...196.4903L
      
    Paper (if ADS pdf and access)    ADS page 

The random walks of small-scale ( ~ 0.2 arcsec) magnetic bright points 
(MBPs) in the lanes between photospheric granules are anomalous. The 
temporal growth of the q-th moment of the displacement r(t) is a power 
law with exponent q gamma (q)/2. For normal, Gaussian walks gamma 
(q)= 1 for all q. However, for the MBP walks on time scales < 45 
minutes we find that gamma (2)<1 and that gamma (q) is a 
decreasing function of q. Many viable models for the heating of coronal 
loops are based on the additon of energy via twisting and braiding of 
magnetic flux lines by the random motions of their footpoints. If the 
MBPs are associated with such footpoints, then the statistics of their 
motions are directly relevant to coronal heating. For example, a number 
of models derive heating rates based on moments of the displacements and 
include the standard assumption that gamma = 1. However, this 
assumption is wrong for MBPs, and the actual value of gamma depends on 
exactly which moment enters the expression. All such models are 
therefore subject to modification. The result gamma (2)<1 is a 
result of pauses in the MBP walks on all time scales (''fractal time'') 
up to ~ 45 min. This implies that the motions of an individual footpoint 
are not statistically stationary. This in turn means that the injection 
of energy into a given loop will be strongly variable and intermittent. 
This can be related to observations of the details of variability in 
coronal loop emissions, giving information on the locations of energy 
deposition and on time scales of energy release. We thus hope to further 
constrain acceptable heating models. This work was supported in part by 
NSF Grant ATM-9628882. 

@--------------------------------------------------------------------
Title:              Anomalous Diffusion of Solar Magnetic Elements
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibliographic Code: 1999ApJ...521..844C
      
    Paper (if ADS pdf and access)    ADS page 

The diffusion properties of photospheric bright points associated with 
magnetic elements (magnetic bright points) in the granulation network 
are analyzed. We find that the transport is subdiffusive for times less 
than 20 minutes but normal for times larger than 25 minutes. The 
subdiffusive transport is caused by the walkers being trapped at 
stagnation points in the intercellular pattern. We find that the 
distribution of waiting times at the trap sites obeys a truncated 
Lvy type (power-law) distribution. The fractal dimension of the 
pattern of sites available to the random walk is less than 2 for the 
subdiffusive range and tends to 2 in the normal diffusion range. We show 
how the continuous time random walk formalism can give an analytical 
explanation of the observations. We simulate this random walk by using a 
version of a phenomenological model of renewing cells introduced 
originally for supergranules by Simon, Title, & Weiss. We find that 
the traps that cause the subdiffusive transport arise when the renewed 
convection cell pattern is neither fixed nor totally uncorrelated from 
the old pattern, as required in Leighton's model, but in some 
intermediate state between these extremes. 

@--------------------------------------------------------------------
Title:              General relativistic solitons. II
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1999PhRvD..59l4019C     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
We investigate the possible existence of nontopological solitons in 
stringlike theories, or in other completions of Einstein theory, by 
examining a simple extension of standard theory that describes a 
nonlinear scalar field interacting with the Einstein, Maxwell, and Weyl 
(dilaton) fields. The Einstein and Maxwell couplings are standard while 
the dilatonic coupling is taken to agree with string models. The 
nonlinear scalar potential is quite general. It is found to be 
impossible to satisfy the dilatonic boundary conditions. Excluding the 
dilaton field we find a variety of solitonic structures differing in 
ways that depend on the nonlinear potential. In general the excited 
states exhibit a discrete mass spectrum. At large distances the 
gravitational field approaches the Reissner-Nordstrm solution. 

@--------------------------------------------------------------------
Title:              Scaling Universality Classes and Analysis of Solar 
                    Data
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibliographic Code: 1999AAS...194.9301L      
    Paper (if ADS pdf and access)    ADS page 

Many solar phenomena display a scaling symmetry associated with random 
multiplicative cascades. Here a physical measure, initially uniform on a 
spatial, temporal, or space-time set, is divided among subsets according 
to randomly determined fractions. This division is repeated on smaller 
and smaller sub-subsets, so that the resulting measure at the smallest 
scale is given at any point by the product of a string of random 
fractions comprising its fragmentation history. Such measures are highly 
intermittent. They characterize such solar phenomena as the spatial 
distribution of magnetic flux in an active region and the time 
distribution of global X-ray emission. The probability distribution 
functions (PDFs) governing the random fractions fall into universality 
classes with robust properties (Hentschel 1994). For example, all PDFs 
which allow for zero fractions lead to measures with local peaks of 
unlimited strengths which are progressively less and less space filling. 
The GOES-2 X-ray data belong to this class, which indicates the presence 
of critical behavior associated with flares (Lu & Hamilton 1991). We 
investigate a number of time series for the presence or absence of this 
property. Multifractals in nature may fall into a narrow universality 
class described by just 3 parameters (Schertzer, et al. 1997). We find 
that at least some examples of active region magnetic fields do indeed 
have the conjectured form. Further, we apply a causal space-time version 
of this class of multiplicative cascade processes to forecasting the 
evolution of solar velocity fields. This work was supported in part by 
NSF grant ATM-9628882. Hentschel, H.G.E. 1994, Phys. Rev. E, 50, 243. 
Lu, E.T. & Hamilton, R.J. 1991, ApJ, 380, L89. Schertzer, D., 
Lovejoy, S., Schmitt, F., Chigirinskaya, Y. & Marsan, D. 1997, 
Fractals, 5, 427. 

@--------------------------------------------------------------------
Title:              Anomalous Diffusion of Solar Magnetic Elements
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibliographic Code: 1999AAS...194.5506C
      
    Paper (if ADS pdf and access)    ADS page 

The diffusion properties of photospheric bright points associated with 
magnetic elements (MBP's) in the granulation network are analyzed. We 
find that the transport is subdiffusive for times less than 20 minutes 
but normal for times larger than 25 minutes. The subdiffusive transport 
is caused by the walkers being trapped at stagnation points in the 
intercellular pattern. We find that the distribution of waiting times at 
the trap sites obeys a truncated Levy type (power law) distribution. The 
fractal dimension of the pattern of sites available to the random walk 
is less than 2 for the subdiffusive range and tends to 2 in the normal 
diffusion range. We show how the continuous time random walk formalism 
can give an analytical explanation of the observations. We simulate this 
random walk by using a version of a phenomenological model of renewing 
cells introduced originally for supergranules by Simon, Title and Weiss 
(1995). We find that the traps which cause the subdiffusive transport 
arise when the renewed convection cell pattern is neither fixed nor is 
it totally uncorrelated from the old pattern as required in Leighton's 
model, but in some intermediate state between these extremes. (Work 
supported in part by NSF grant ATM-9628882). 

@--------------------------------------------------------------------
Title:              Characteristic Scales of Photospheric Flows and 
                    Their Magnetic and Temperature Markers
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibliographic Code: 1999ApJ...513..506L
      
    Paper (if ADS pdf and access)    ADS page 

We study the characteristic scales of quiet-Sun photospheric velocity 
fields along with their temperature and magnetic markers in Doppler 
images from the Michelson Doppler Imager aboard the SOHO satellite 
(SOHO/MDI) in simultaneous, Doppler, magnetic, and intensity images from 
the San Fernando Observatory and in full-disk magnetograms and an 
intensity image from National Solar Observatory (Kitt Peak). Wavelet 
flatness spectra show that velocity fluctuations are normally 
distributed (Gaussian). This is often assumed in stochastic models of 
turbulence but had not yet been verified observationally for the Sun. 
Temperature fluctuations also are Gaussian distributed, but magnetic 
fields are intermittent and are gathered into patterns related to flow 
structures. Wavelet basis functions designed to detect characteristic 
convection cell-flow topologies in acoustically filtered SOHO/MDI 
Doppler images reveal granulation scales of 0.7-2.2 Mm and 
supergranulation scales of 28-40 Mm. Mesogranular flows are weakly but 
significantly detected in the range 4-8 Mm. The systematic flows account 
for only 30% of the image variances at granular and supergranular scales 
and much less in between. The main flows for the intermediate range of 
2-15 Mm are self-similar, i.e., chaotic or turbulent. 

@--------------------------------------------------------------------
Title:              Kerr-Schild Description of a Rotating Dyon
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1999GReGr..31...31C
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              Spatiotemporal Correlations and Turbulent 
                    Photospheric Flows from SOHO/MDI Velocity Data
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.;
                    Walton, S. R.; Tarbell, T.
Bibliographic Code: 1998ApJ...509..918C
      
    Paper (if ADS pdf and access)    ADS page 

Time series of high-resolution and full-disk velocity images obtained 
with the Michelson Doppler Imager (MDI) instrument on board SOHO have 
been used to calculate the spacetime spectrum of photospheric velocity 
flow. The effects of different methods for filtering acoustic 
oscillations have been carefully studied. It is found that the spectra 
show contributions both from organized structures that have their origin 
in the convection zone and from the turbulent flow. By considering time 
series of different duration and cadence in solar regions with different 
line-of-sight projections, it is possible to distinguish the 
contributions of the spectra from the two different kinds of flows. The 
spectra associated with the turbulent velocity fields obey power laws 
characterized by two scaling parameters whose values can be used to 
describe the type of diffusion. The first parameter is the spectral 
exponent of the spatial correlation function and the second is a scaling 
parameter of the time correlation function. Inclusion of the time 
parameter is an essential difference between the present work and other 
solar studies. Within the confidence limits of the data, the values of 
the two parameters indicate that the turbulent part of the flow in the 
scale range 16-120 Mm produces superdiffusive transport. 

@--------------------------------------------------------------------
Title:              General relativistic solitons
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1998PhRvD..57.7318C
      
    Paper (if ADS pdf and access)    ADS page 

A general relativistic and nontopological soliton is constructed by 
coupling a nonlinear scalar field to the standard gravitational field. 
Our results replicate the basic features of the special relativistic 
case: namely, a singularity-free lump with a discrete spectrum of 
eigensolutions. The central singularities and horizon that appear in the 
black hole solitons of string theory are not present. 

@--------------------------------------------------------------------
Title:              Dyonic Black Holes and Related Solitons
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1997gr.qc.....7031C     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
There is a growing literature on dyonic black holes as they appear in 
string theory. Here we examine the correspondence limit of a dyonic 
black hole which is not supersymmetric. Assuming the existence of a dyon 
with non-supersymmetric Kerr-Schild structure, we calculate its 
gravitational and electromagnetic fields and compute its mass and 
angular momentum to obtain a modified B.P.S. relation. The contributionn 
of the angular momentum to the mass appears in the condition for the 
appearance of a horizon. 

@--------------------------------------------------------------------
Title:              Decorrelation Time of Fourier modes in the Spectrum 
                    of Solar Background Velocity Fields
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibliographic Code: 1997SPD....28.0261C      
    Paper (if ADS pdf and access)    ADS page 

We calculate the power-energy spectrum of time series of SOHO/MDI 
line-of sight high resolution Doppler images near disk center. While the 
spatial spectrum presents velocity features at characteristic scales and 
not a cascade in wavenumber space, we investigate the extent to which it 
is still possible to describe in terms of a scaling exponent the 
properties of the decorrelation time for each Fourier mode as a function 
of wavelength. We explore the sensitivity of the result to different 
methods for removing the contribution of the p-modes to the spectrum. 

@--------------------------------------------------------------------
Title:              Scale Dependence of Photospheric Magnetic, Velocity 
                    and Temperature Structure
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibliographic Code: 1997SPD....28.0247L
      
    Paper (if ADS pdf and access)    ADS page 

Time series fluctuations may show different structure when observed at 
different time scale resolutions. Thus, wavelet analysis reveals that 
fluctuations in the International Sunspot Number are intermittent (that 
is, distributed with kurtosis K>0) on scales less than 2 yr, but 
truncated (K<0) on time scales between 2-8 yr. Terrestrial 
temperature fluctuations are normally distributed (K=0) over discrete 
timescale bands (<1 yr, 4-6 yr, 13 yr) interspersed by regimes of 
intermittence (1-4 yr) and truncation (6-13 yr). Similar effects occur 
for spatial phenomena. We employ various continuous, two-dimensional 
wavelets to analyze digital solar images in Cartesian projection 
(simultaneous, co-registered San Fernando Observatory magnetic, Doppler 
and continuum images; SOHO/MDI high resolution Doppler images) and 
full-disk images in hemispheric projection (KPNO magnetograms, SOHO/MDI 
Doppler images). The temperature and velocity data are normally 
distributed at all scales up to 64 arc sec, though the temperature 
gradients are slightly intermittent (K~1). The magnetic data are mostly 
intermittent. Wavelet power spectra for KPNO full-disk magnetograms are 
quite featureless and indicate scale invariance of the magnetic 
structures. Structural spectra of both active and quiet sun images, 
however, show a strong peak in intermittence at a scale near 8 arc sec. 
Wavelet analysis permits localization of structures in space as well as 
in spatial scale. The highly intermittent structures can be mapped and 
are found to be located not in active regions but in some, though not 
all, areas of low magnetic activity. We discuss possible physical 
relationships among the magnetic, velocity and temperature distributions 
studied. 

@--------------------------------------------------------------------
Title:              Wavelet and Multifractal Analyses of Spatial and 
                    Temporal Solar Activity Variations
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibliographic Code: 1997scma.conf..421L
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              Spectral Properties of Solar Convection and 
                    Diffusion
Authors:            Ruzmaikin, A. A.; Cadavid, A. C.; Chapman, G. A.;
                    Lawrence, J. K.; Walton, S. R.
Bibliographic Code: 1996ApJ...471.1022R
      
    Paper (if ADS pdf and access)    ADS page 

We present the results of a study of the scaling properties of solar 
photo spheric motions. We use time series of Doppler images obtained in 
good seeing conditions with the San Fernando Observatory 28 cm vacuum 
telescope and vacuum spectroheliograph in video 
spectra-spectroheliograph mode. Sixty line-of- sight Doppler images of 
an area of the quiet Sun near disk center are investigated. They were 
taken at 60 s intervals over a 1 hr time span at &tilde;2" resolution. 
After filtering to remove 5 minute acoustic oscillations, the 
time-spatial spectrum of the velocity is calculated. To study the 
turbulence of photospheric flows in the mesogranulation scale range, we 
estimate two scaling parameters in the spectrum: the exponent of the 
spatial part of the power spectrum and the exponent governing the 
scaling of time correlations of each spatial mode. These parameters 
characterize the type of diffusion involved and the fractal dimension of 
the diffusion front. Our results indicate that the turbulent diffusion 
produced by motions in this scale range is not normal diffusion but 
superdiffusion. 

@--------------------------------------------------------------------
Title:              The q-Coulomb problem in configuration space
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1996JMP....37.3675C
      
    Paper (if ADS pdf and access)    ADS page 

We formulate the q-Coulomb problem in configuration space with the aid 
of ladder operators for the radial wave function. The highest angular 
momentum state corresponding to the principal quantum number n is found 
to be the monomial r<SUP>n-1</SUP> multiplied by a q-exponential. The 
states of lower angular momentum are q-associated Laguerre polynomials 
multiplied by the same q-exponential. The state functions all lie in the 
complex plane and may be interpreted in the standard way. The energy 
levels are again given by a Balmer formula with n replaced by the basic 
n. 

@--------------------------------------------------------------------
Title:              On the Multifractal Distribution of Solar Magnetic 
                    Fields: Erratum
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibliographic Code: 1996ApJ...467..473L
      
    Paper (if ADS pdf and access)    ADS page 

Many studies have pointed out fractal and multifractal properties of 
photospheric magnetic fields, but placing the various approaches into 
context has proved difficult. Although fractal quantities are defined 
mathematically in the asymptotic limit of infinite resolution, real data 
cannot approach this limit. Instead, one must compute fractal dimensions 
or multifractal spectra within a limited range at finite scales. The 
consequent effects of this are explored by calculation of fractal 
quantities in finite images generated from analytically known measures 
and also from solar data. We find that theorems relating asymptotic 
quantities need not hold for their finite counterparts, that different 
definitions of fractal dimension that merge asymptotically give 
different values at finite scales, and that apparently elementary 
calculations of dimensions of simple fractals can lead to incorrect 
results. We examine the limits of accuracy of multifractal spectra from 
finite data and point out that a recent criticism of one approach to 
such problems is incorrect. 

@--------------------------------------------------------------------
Title:              On the Multifractal Distribution of Solar Magnetic 
                    Fields [ Erratum: 1996ApJ...467..473L ]
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibliographic Code: 1996ApJ...465..425L
      
    Paper (if ADS pdf and access)    ADS page 

Many studies have pointed out fractal and multifractal properties of 
photospheric magnetic fields, but placing the various approaches into 
context has proved difficult. Although fractal quantities are defined 
mathematically in the asymptotic limit of infinite resolution, real data 
cannot approach this limit. Instead, one must compute fractal dimensions 
or multifractal spectra within a limited range at finite scales. The 
consequent effects of this are explored by calculation of fractal 
quantities in finite images generated from analytically known measures 
and also from solar data. We find that theorems relating asymptotic 
quantities need not hold for their finite counterparts, that different 
definitions of fractal dimension that merge asymptotically give 
different values at finite scales, and that apparently elementary 
calculations of dimensions of simple fractals can lead to incorrect 
results. We examine the limits of accuracy of multifractal spectra from 
finite data and point out that a recent criticism of one approach to 
such problems is incorrect. 

@--------------------------------------------------------------------
Title:              Spectral Properties of the Solar Background Velocity 
                    Field
Authors:            Cadavid, A. C.; Chapman, G. A.; Lawrence, J. K.;
                    Ruzmaikin, A. A.; Walton, S. R.
Bibliographic Code: 1996AAS...188.3506C
      
    Paper (if ADS pdf and access)    ADS page 

We study the scaling properties of time series of Doppler images 
obtained in good seeing conditions with the San Fernando Observatory 28 
cm vacuum telescope and vacuum spectroheliograph in video 
spectra-spectroheliograph mode. The images correspond to two areas of 
quiet Sun near disk center taken at 60 second intervals from one hour to 
six hour spans at ~ 2 arcsec resolution. After removal of 5 min acoustic 
oscillations the time-spatial spectrum of the velocity is calculated. To 
study the turbulence of photospheric flows we estimate two scaling 
parameters: the exponent of the spatial part of the power spectrum and 
the exponent governing the scaling of time correlations of each spatial 
mode. The implied diffusive behavior produced by the solar convection in 
the mesogranulation scale range is discussed. This includes 
characterization of the type of diffusion involved and the fractal 
dimension of the diffusion front. 

@--------------------------------------------------------------------
Title:              Turbulent and Chaotic Dynamics Underlying Solar 
                    Magnetic Variability
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibliographic Code: 1995ApJ...455..366L
      
    Paper (if ADS pdf and access)    ADS page 

We examine the temporal scaling properties of solar magnetic activity on 
timescales from days to decades. Because of more than 63,000 usable data 
points, we concentrate on the daily International Sunspot Number. Some 
results have been checked with other data sets, primarily the 10.7 cm 
microwave flux with about 16,000 data points. Such time series provide a 
measure whose scaling and intermittency properties are analyzed. 
By means of correlation analysis and both Fourier and wavelet spectral 
analysis, we distinguish two regimes of temporal behavior of the 
magnetic variability. The scaling of the time series is analyzed in 
terms of multiplicative cascade processes which prove to be invariant 
over more than two decades of scale from about 2 yr down to about 2 days 
or less. We interpret this result to indicate generic turbulent 
structuring of the magnetic fields as they rise through the convection 
zone. We find that a low-dimensional, chaotic behavior in the sunspot 
number operates entirely at timescales longer than a transition 
threshold scale of about 8 yr. Magnetic variability on timescales 
between 2 yr and 8 yr apparently requires handling by direct simulation. 

@--------------------------------------------------------------------
Title:              Clebsch-Gordan coefficients and related identities 
                    obtained by an integration over the group space of 
                    SU<SUB>q</SUB>(2)
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1995JMP....36.1912C
      
    Paper (if ADS pdf and access)    ADS page 

The Clebsch-Gordan coefficients of SU<SUB>q</SUB>(2) are here calculated 
by an integration over the group manifold following the Woronowicz 
prescription. A representation is obtained that is different from the 
one derived from the q-group algebra. The equivalency of the two results 
implies a q-identity and establishes a relation between q-hypergeometric 
functions. In the limit q=1, our result gives a different expression for 
the Clebsch-Gordan coefficients of SU(2), and the q-identity relation 
reduces to an identity between binomial coefficients. The Woronowicz 
technique is extended to calculate the integral of the product of many 
irreducible representations. A summary of the main results has already 
been presented elsewhere. 

@--------------------------------------------------------------------
Title:              Turbulence and Chaos in Solar Variability
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.
Bibliographic Code: 1995SPD....26..514C
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              Integration over the group space of SU q(2), 
                    Clebsch-Gordan coefficients, and related identities
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1995LMaPh..33..221C
      
    Paper (if ADS pdf and access)    ADS page 

We calculate the Clebsch-Gordan coefficients of SU q(2) by a Woronowicz 
integration over the group manifold and obtain a representation 
differing from that reached by working with the q-group algebra. These 
apparently different results must agree, however, and their equivalence 
implies a q-identity. On letting q = 1, we shall obtain two results of 
different structures for the Clebsch-Gordan coefficients of SU(2) and 
their equivalence similarly implies an identity among the usual binomial 
coefficients. With the same approach, one may extend the Woronowicz 
integral of the product of two irreducible representations to products 
of many irreducible representations. 

@--------------------------------------------------------------------
Title:              11-Dimensional supergravity compactified on 
                    Calabi-Yau threefolds
Authors:            Cadavid, A. C.; Ceresole, A.; D'Auria, R.;
                    Ferrara, S.
Bibliographic Code: 1995PhLB..357...76C     ArXiv preprint 
    Paper (if ADS pdf and access)    ADS page 
We consider generic features of eleven dimensional supergravity 
compactified down to five dimensions on an arbitrary Calabi-Yau 
threefold. The possible relation with the heterotic string compactified 
on K3  S<SUB>1</SUB> is discussed. 

@--------------------------------------------------------------------
Title:              Multiplicative cascade models of multifractal solar 
                    magnetic fields
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibliographic Code: 1995PhRvE..51..316L      
    Paper (if ADS pdf and access)    ADS page 

We present a multifractal analysis of digital, photoelectric images of 
line-of-sight magnetic fields in solar active regions and quiet 
photosphere. We study a positive definite measure related to the Ohmic 
dissipation of magnetic energy. After calculation of the multifractal 
spectrum directly and by scaling of the moments of the measure, we focus 
on a multiplicative cascade approach. We infer a scale-invariant rule by 
which the Ohmic dissipation measure is allocated among subsets of its 
support through a hierarchy of scales. Knowledge of this rule, which is 
hampered to some extent by image noise, permits the calculation of the 
multifractal spectrum to great accuracy. The scaling of the solar 
dissipation field resembles that of fully developed turbulence in an 
atmospheric boundary layer. The cascade multiplier probability 
distribution is itself a very useful quantity. It allows a convenient 
display of image properties, such as self-similarity. Further, it is 
more closely related than the multifractal spectrum to the physics of 
the turbulent field evolution, and it thus can be used to impose 
stronger constraints on turbulent dynamo models of magnetic field 
generation. 

@--------------------------------------------------------------------
Title:              Spectra of Solar Magnetic Fields and Diffusion
Authors:            Ruzmaikin, A. A.; Cadavid, A. C.; Chapman, G. A.;
                    Lawrence, J. K.; Walton, S. R.
Bibliographic Code: 1995ASPC...76..292R
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              Multifractal models of small-scale solar magnetic 
                    fields
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.;
                    Kayleng-Knight, A.
Bibliographic Code: 1994ApJ...429..391C
      
    Paper (if ADS pdf and access)    ADS page 

We generate, both analytically and numerically, artifical, 
two-dimensional images composed of a known self-similar, and thus 
multifractal measured with added Gaussian white noise. These are used to 
interpret observed, line-of-sight, solar magnetic field distributions 
noisy multifractals. The range of self-similar scaling of observed, 
distributions is extended beyond that of previous work. Our 
interpretation of the data is then used to confront theoretical models 
for the generation of small-scale solar magnetic fields. We investigate 
the multifractial structure of the field generated by two-dimensional, 
random cell dynamos and find that self-similarity is relatively enhanced 
for more intermittent distributions and strong correlations between 
cells. An optimum value of the intercellular diffusion coefficient 
maximizes the degree of intermittency. The simulated field from a 
linear, kinematic, fast dynamo with two-dimensional, chaotic, 'ABC' flow 
displays scaling properties resembling those of observed solar fields. 
We suggest that the chaotic element of this model is the crucial 
ingredient for the long-range correlations that lead to multifractal 
scaling. 

@--------------------------------------------------------------------
Title:              Scaling properties of photospheric magnetic fields
Authors:            Lawrence, J. K.; Cadavid, A. C.; Ruzmaikin, A. A.
Bibliographic Code: 1994ssm..work..279L
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              Multifractal Measure of the Solar Magnetic Field
Authors:            Lawrence, J. K.; Ruzmaikin, A. A.; Cadavid, A. C.
Bibliographic Code: 1993ApJ...417..805L
      
    Paper (if ADS pdf and access)    ADS page 

We analyze high-resolution, digital, photoelectric images of solar 
photospheric magnetic fields. The line-of-sight fields are found to 
scale in a self-similar way with resolution and thus can be expressed in 
the form of a signed multifractal measure. The scaling properties of the 
measure are used to extrapolate field integrals, such as moments of the 
magnetic field, below resolvable limits. The scaling of the field 
moments is characteristic of highly intermittent fields. We suggest that 
the quiet-Sun photospheric fields are generated by local dynamo action 
based on random convective motions at high magnetic Reynolds number. The 
properties of active region images are determined by the presence of 
fields generated by the global, mean field dynamo. 

@--------------------------------------------------------------------
Title:              Solar Magnetic Fields, Multifractals and Dynamos
Authors:            Cadavid, A. C.; Lawrence, J. K.; Ruzmaikin, A. A.;
                    Kayleng-Knight, A.
Bibliographic Code: 1993BAAS...25R1206C
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              Multiscale Measure of the Solar Magnetic Field
Authors:            Ruzmaikin, A. A.; Lawrence, J. K.; Cadavid, A. C.
Bibliographic Code: 1993BAAS...25.1219R
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              Self-Similarity in Solar Magnetic Images
Authors:            Lawrence, J. K.; Ruzmaikin, A. A.; Cadavid, A. C.
Bibliographic Code: 1993BAAS...25.1219L
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              The Affine N = 4 Yang-Mills Theory
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1992IJMPA...7.2469C
      
    Paper (if ADS pdf and access)    ADS page 

An affine field theory may be constructed by gauging an affine algebra. 
The momentum integrals of the affine N = 4 Yang-Mills theory are 
ultraviolet finite but diverge because the sum over states is infinite. 
If the affine symmetry is broken by postulating a nonvanishing vacuum 
expectation value for that component of the scalar field lying in the 
L<SUB>0</SUB> direction, then the theory acquires a linear mass 
spectrum. This broken theory is ultraviolet finite too, but the mass 
spectrum is unbounded. If it is also postulated that the mass spectrum 
has an upper bound (say, the Planck mass), then the resulting theory 
appears to be altogether finite. The influence of the exotic states has 
been estimated and, according to the proposed scenario, is negligible 
below energies at which gravitational interactions become important. The 
final effective theory has the symmetry of a compact Lie algebra 
augmented by the operator L<SUB>0</SUB>. 

@--------------------------------------------------------------------
Title:              The star exponential and path integrals on compact 
                    groups
Authors:            Cadavid, A. C.; Nakashima, M.
Bibliographic Code: 1991LMaPh..23..111C
      
    Paper (if ADS pdf and access)    ADS page 

Using the star exponential, a path integral is constructed for arbitrary 
compact Lie groups. This is a globalization of the results of Alcalde, 
Cadavid, and Nakashima, in which a path integral was constructed for 
SU(2) in terms of local coordinates. Also the phase factor encountered 
by Alcalde, Cadavid, and Nakashima is shown to be zero. 

@--------------------------------------------------------------------
Title:              The star exponential and SU(2) path integrals
Authors:            Alcalde, C. A.; Cadavid, A. C.; Nakashima, M.
Bibliographic Code: 1991LMaPh..22...15A
      
    Paper (if ADS pdf and access)    ADS page 

An expression is found for the Feynman path integral on SU(2) in terms 
of the star-exponential. 

@--------------------------------------------------------------------
Title:              (2,2) vacuum configurations for type IIA 
                    superstrings: N=2 supergravity Lagrangians and 
                    algebraic geometry
Authors:            Bodner, M.; Cadavid, A. C.; Ferrara, S.
Bibliographic Code: 1991CQGra...8..789B
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              Calabi-Yau supermoduli space, field strength duality 
                    and mirror manifolds
Authors:            Ferrara, Sergio; Bodner, Mark; Cadavid, Ana Cristina
Bibliographic Code: 1990PhLB..247...25F
      
    Paper (if ADS pdf and access)    ADS page 

Calabi-Yau moduli space have a super extension due to their relation to 
type II superstring compactifications. Supermoduli can be defined as N = 
2 target space vector-supermultiplets containing both the moduli and 
their vector field bosonic superpartners. A change of basis in the 
cohomology vector space corresponds to (modular) duality transformations 
of target space vector field strengths. Target space two-forms will take 
values in the cohomology spaces of Calabi-Yau manifolds, and are 
therefore related to the Khler class and complex structure 
deformations, which may be relevant for the description of mirror 
symmetries of (2, 2) superconformal field theories. 

@--------------------------------------------------------------------
Title:              Dimensional reduction of type IIB supergravity and 
                    exceptional quaternionic manifolds
Authors:            Bodner, M.; Cadavid, A. C.
Bibliographic Code: 1990CQGra...7..829B
      
    Paper (if ADS pdf and access)    ADS page 


@--------------------------------------------------------------------
Title:              Affine Higgs Effect
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1990MPLA....5..613C
      
    Paper (if ADS pdf and access)    ADS page 

The Higgs mechanism is investigated for the affine version of the N=4 
Yang-Mills theory. 

@--------------------------------------------------------------------
Title:              Dyons in affine field theories
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1989JMP....30.2674C
      
    Paper (if ADS pdf and access)    ADS page 

By postulating that the gauge vector field and the Higgs field both lie 
in an affine algebra rather than a Lie algebra, an affine field theory 
with an expanded soliton sector is obtained. An infinite family of 
exact, special solutions of the new equations corresponding to the 
original 't Hooft-Polyakov solitonic solutions, is now found. A 
perturbation method for an arbitrary solution of the new equation is 
also proposed. 

@--------------------------------------------------------------------
Title:              Spontaneous symmetry breaking of affine field theory
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1989LMaPh..17..157C
      
    Paper (if ADS pdf and access)    ADS page 

It is possible to construct non-Abelian field theories by gauging 
Kac-Moody algebras. Here we discuss the spontaneous symmetry breaking of 
such theories via the Higgs mechanism. If the Higgs particle lies in the 
Cartan subalgebra of the Kac-Moody algebra, the previously massless 
vectors acquire a mass spectrum that is linear in the Kac-Moody index 
and has additional fine structure depending on the associated Lie 
algebra. 

@--------------------------------------------------------------------
Title:              Affine Field Theories.
Authors:            Cadavid, Ana Cristina
Bibliographic Code: 1989PhDT.......124C
      
    Paper (if ADS pdf and access)    ADS page 

We construct a non-Abelian field theory by gauging a Kac-Moody algebra, 
obtaining an infinite tower of interacting vector fields and associated 
ghosts, that obey slightly modified Feynman rules. We discuss the 
spontaneous symmetry breaking of such theory via the Higgs mechanism. If 
the Higgs particle lies in the Cartan subalgebra of the Kac -Moody 
algebra, the previously massless vectors acquire a mass spectrum that is 
linear in the Kac-Moody index and has additional fine structure 
depending on the associated Lie algebra. We proceed to show that there 
is no obstacle in implementing the affine extension of supersymmetric 
Yang-Mills theories. The result is valid in four, six and ten space-time 
dimensions. Then the affine extension of supergravity is investigated. 
We discuss only the loop algebra since the affine extension of the 
super-Poincare algebra appears inconsistent. The construction of the 
affine supergravity theory is carried out by the group manifold method 
and leads to an action describing infinite towers of spin 2 and spin 3/2 
fields that interact subject to the symmetries of the loop algebra. The 
equations of motion satisfy the usual consistency check. Finally, we 
postulate a theory in which both the vector and scalar fields lie in the 
loop algebra of SO(3). This theory has an expanded soliton sector, and 
corresponding to the original 't Hooft-Polyakov solitonic solutions we 
now find an infinite family of exact, special solutions of the new 
equations. We also propose a perturbation method for obtaining an 
arbitrary solution of those equations for each level of the affine 
index. 

@--------------------------------------------------------------------
Title:              Affine Extension of Supergravity
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1989IJMPA...4.5511C
      
    Paper (if ADS pdf and access)    ADS page 

The affine extension of supergravity is investigated. We discuss only 
the loop algebra since the affine extension of the super-Poincar 
algebra appears inconsistent. The construction of the affine 
supergravity theory has been carried out by the group manifold method 
and leads to an action describing infinite towers of gravitons and 
gravitinos that interact subject to the symmetries of the loop algebra. 
The equations of motion satisfy the usual consistency check. 

@--------------------------------------------------------------------
Title:              Affine Extension of Supersymmetric Field Theory
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1989IJMPA...4.2967C
      
    Paper (if ADS pdf and access)    ADS page 

It is shown that there is no obstacle to the affine extension of 
supersymmetric Yang-Mills theories. This result holds equally for loop 
and Kac-Moody algebras. It also holds for 4, 6, and 10 dimensions. By 
dimensional reduction of the 10-dimensional theory one obtains a 
supersymmetric action describing interacting Kac-Moody fields in four 
dimensions. 

@--------------------------------------------------------------------
Title:              Gauged Kac-Moody algebras
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1988LMaPh..16..279C
      
    Paper (if ADS pdf and access)    ADS page 

We construct a non-Abelian field theory by gauging a Kac-Moody algebra. 
One obtains an infinite tower of interacting vector fields and 
associated ghosts obeying slightly modified Feynman rules.

Rob Rutten 2014-10-16