file: solabs_cadavid.html = solar physics author: cadavid
last: Jan 20 2016
explanation     parallel bibtex collection for author: cadavid

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Title:              Correlation and scaling properties of non-stationary
intensity fluctuations in coronal EUVtime series in
different physical environments
Authors:            Cadavid, Ana Cristina; Lawrence, John; Rivera, Yeimy
Bibliographic Code: 2015TESS....120307C

Previously we have used EUV observations from AIA/SDO to examine
properties of energy deposition into coronal-loops in non-flaring active
region (AR) cores. The evolution of the loop apex intensity,
temperature, and electron density indicate that the loops are
impulsively heated in a mode compatible with high intensity nanoflare
storms characterized by a progressive cooling pattern in the EUV lines
with the hot channels leading the emission. Spectra of the hot 131
Å intensity (basically Fe XXI) and of the energy dissipation in a
2D model of loop magneto-turbulence compatible with nanoflare
statistics, both exhibit three scaling regimes with low frequencies
corresponding to 1/f noise, the intermediate range indicating a
persistent process, and high frequencies corresponding to white noise.
The varying power law behavior in these spectra indicates that both the
observational and the simulated time series are not stationary.
Therefore to extend the analysis beyond the AR loops we apply the method
of detrended fluctuation analysis (DFA) that was developed to study the
long-range correlations in non-stationary signals. DFA provides a
scaling exponent that characterizes the correlation properties of the
signal and which can be related both to the spectral exponents and to
the Hurst exponent. In areas of diffuse emission and for all the
spectral channels the time series of intensity fluctuations are
characterized by scaling exponents that indicate a weak positive
correlation across all time scales. In regions with intermittent
intensity brightenings a cross-over occurs at timescales near 10 - 20
min with different exponents describing the degree of positive
correlation of the intensity fluctuations at short and long time scales.
Qualitative differences exist between the exponents of the hotter and
the cooler channels. We have further compared the scaling properties of
the time series associated with different physical environments
distinguished by the possibility of underlying nanoflare storms, or by
the strength of the magnetic field in contemporaneous HMI images.
Another comparison is made to the scaling properties of simulations of
energy dissipation in magnetoturbulence.

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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: 2014ApJ...795...48C     ArXiv preprint
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 Å intensity channel. We
isolate the hot Fe XVIII and Fe XXI components of the 94 Å and 131
Å by modeling and subtracting the "warm" contributions to the
emission. HMI/SDO data allow us to focus 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 Å 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 Å 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 Å signals, when
averaged over the five loops, present three scaling regimes with break
frequencies near 0.1 min<SUP>-1</SUP> and 0.7 min<SUP>-1</SUP>. 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 2D
"hybrid" shell model of loop magneto-turbulence, based on reduced
magnetohydrodynamics, that 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.;
Bibliographic Code: 2014SoPh..289..649C

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

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 94Å fluctuations
(Figure 1) have structure on timescales shorter than radiative and
conductive cooling times. Each of several strong 94Å brightenings
is followed after ~8 min by a broader peak in the cooler 335Å
emission. This indicates that we see emission from the hot component of
the 94Å contribution function. No hotter contributions appear, and
we conclude that the 94Å intensity can be used as a proxy for
energy injection into the loop plasma. The probability density function
of the observed 94Å 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

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 94Å band of Fe XVIII,
implying an effective temperature ~ 7 MK. The low temperature component
of the 94 Å signal is modeled in terms of a linear superposition
of the 193 Å and 171 Å 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 (94Å,
335Å, 211Å) is characterized by hotter temperatures (~2-7
MK), and Group 2 (193Å, 171Å, 131Å) by cooler
temperatures (0.4 - 1.6 MK). For Group 1 the intensity peaks in the
94Å channel are followed by maxima in the 335 Å channel with
a time lag of ~8 min, suggestive of a cooling pattern with an
exponential decay. While the 211Å maxima follow those in the 335
Å 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
131Å channels track each other closely, and lag behind the
193Å. In the inter-moss region of the loop the peak temperature
and peak emission measure have opposite trends. The hot 94Å
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 Å 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 94Å 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

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
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
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

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 94Å 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 (94Å, 335Å, 211Å) characterized by hotter
temperatures  2-6 MK), and group B (193Å, 171Å, 131Å)
by cooler temperatures (0.4 - 1.6 MK). In loop 1 (group A) the intensity
peaks in the 94Å channel are followed by maxima in the 335 Å
channel with a time lag of ~10 min, suggestive of a cooling pattern with
an exponential decay. The 211Å maxima follow those in the 335
Å channel, but there is no systematic relation which would
indicate a progressive cooling process. In group B the signals in the
171 and 131Å channels track each other closely, and tend to lag
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 171Å 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 Å to 335 Å 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 94Å 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 (94Å, 335Å, 211Å) characterized by hotter
temperatures  2-6 MK), and group B (193Å, 171Å, 131Å)
by cooler temperatures (0.4 - 1.6 MK). In loop 1 (group A) the intensity
peaks in the 94Å channel are followed by maxima in the 335 Å
channel with a time lag of ~10 min, suggestive of a cooling pattern with
an exponential decay. The 211Å maxima follow those in the 335
Å channel, but there is no systematic relation which would
indicate a progressive cooling process. In group B the signals in the
171 and 131Å channels track each other closely, and tend to lag
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 171Å 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 Å to 335 Å 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

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 &asymp; 6, which includes almost all  the data, is
characterized by low intensities and low UHF power. State 2, with
kappa &asymp; 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.; Wöger, F.;
Schlichenmaier, R.; Carlsson, M.; Berger, T.;
Cadavid, A.; Gilbert, P. R.; Goode, P. R.;
Knölker, M.
Bibliographic Code: 2012ASPC..463.....R

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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

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
Å, 171 Å and 193 Å 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 Å and 193 Å
coronal lines the brightenings are localized impulses in time, but in
the transition region line at 304 Å they are more extended in
time. The intensity traces in the 304 Å 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
Å 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
Å 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

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 94Å 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 Å 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 Å 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 Å
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 Å 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

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.

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Title:              Climate Science Program at California State
University, Northridge
Authors:            Steele Cox, H.; Klein, D.; Cadavid, A. C.; Foley, B.
Bibliographic Code: 2012AGUFMED33A0746S

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, César; Gil, Eduardo;
de la Rubia, Óscar; Martínez, María;
Rubio, Francisca; Cadavid, Andros; Navarro, José
Hillenbrand, Sascha; Ballesteros-Sánchez, Isabel;
Castillo-Cagigal, Manuel; Masa-Bote, Daniel;
Matallanas, Eduardo; Caamaño-Martín, Estefanía;
Gutiérrez, Álvaro
Bibliographic Code: 2012AIPC.1477..360T

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.

@--------------------------------------------------------------------
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
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 20±1 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
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

We studied 1 - 24 mHz intensity fluctuations in 3-hour sequences of
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 Å) Ca II K-line core compared to
the more broadband (3 Å) 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

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 4305.5Å, bandpass 9.2Å, 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 3933.7Å, bandpass 1.0Å, 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
We study the space - time distributions of intensity fluctuations
in 2 - 3 hour sequences of multi-spectral, high-resolution,
- 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

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

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

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 3±1 sec and H trails
|B| by 6±1 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

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

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

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
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 27.03±0.02 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 27.04±0.03 days in the North and at
28.24±0.03 days in the South. These are replaced during cycle 23
by one at 26.45±0.03 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
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

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

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

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

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
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

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

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;
Bibliographic Code: 2005AAS...207.6344M

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

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

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

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 1600Å and
1700Å 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

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

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

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

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.;

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

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

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

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

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

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 Å ),
Ca II K (3934 Å ), two (6563 Å) Halpha channels offset by
0.35 Å and 0.7 Å , and Fe I (6302 Å) 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

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 Å,
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

@--------------------------------------------------------------------
Title:              A simple model of solar variability influence on
climate.
Authors:            Ruzmaikin, A.; Lawrence, J.; Cadavid, A.
Bibliographic Code: 2002cosp...34E.336R

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:              Alfvén Wave Generation by Multifractal Solar
Magnetic Fields
Authors:            Lawrence, J.; Cadavid, A.; Ruzmaikin, A.
Bibliographic Code: 2001AGUFMNG21A0402L

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
Alfvén 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 Alfvén 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 Alfvén and fast mode MHD waves. The
Alfvén 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

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
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
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

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

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

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

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

@--------------------------------------------------------------------
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

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

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
Lévy 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
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-Nordström 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

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

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

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

@--------------------------------------------------------------------
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

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

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
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

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

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

@--------------------------------------------------------------------
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

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

We formulate the q-Coulomb problem in configuration space with the aid
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

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

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

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

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
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

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

@--------------------------------------------------------------------
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

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
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

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

@--------------------------------------------------------------------
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

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: 1994ASIC..433..279L

@--------------------------------------------------------------------
Title:              Multifractal Measure of the Solar Magnetic Field
Authors:            Lawrence, J. K.; Ruzmaikin, A. A.; Cadavid, A. C.
Bibliographic Code: 1993ApJ...417..805L

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

@--------------------------------------------------------------------
Title:              Multiscale Measure of the Solar Magnetic Field
Authors:            Ruzmaikin, A. A.; Lawrence, J. K.; Cadavid, A. C.
Bibliographic Code: 1993BAAS...25.1219R

@--------------------------------------------------------------------
Title:              Self-Similarity in Solar Magnetic Images
Authors:            Lawrence, J. K.; Ruzmaikin, A. A.; Cadavid, A. C.
Bibliographic Code: 1993BAAS...25.1219L

@--------------------------------------------------------------------
Title:              The Affine N = 4 Yang-Mills Theory
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1992IJMPA...7.2469C

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

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

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

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

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 Kähler 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

@--------------------------------------------------------------------
Title:              Affine Higgs Effect
Authors:            Cadavid, A. C.; Finkelstein, R. J.
Bibliographic Code: 1990MPLA....5..613C

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

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

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.
Bibliographic Code: 1989PhDT.......124C

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

The affine extension of supergravity is investigated. We discuss only
the loop algebra since the affine extension of the super-Poincaré
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

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

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
2016-01-20

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