ANNOUNCEMENT
The College of Natural Sciences
The University of Texas at Austin
1996 Undergraduate Research Poster Session
The College of Natural Sciences will
sponsor its Fourth Annual Undergraduate Research Poster Session
from 11:00 AM to 2:00 PM on Friday, April 26, 1996 in the Ground
Floor Hallway of Welch. This will be an opportunity for College
undergraduate students conducting research under the supervision
of University faculty and staff to present their work publicly.
SRIRAM BALA, Departments of Biology &
Chemistry and Biochemistry,
Hydrogen Bond Patterns in Crystals
JENNIFER L. BEALL, . Department of Geological Sciences,
Occurrence of Marine Radiaxial Calcite Through Phanerozoic
Time
JAMES CRAWFORD, Department of Astronomy,
A Study of Near-Infrared H2 Emission in Planetary
Nebulae
CASEY GREEN, Genetics Institute, RRR-alpha-Tocopheryl
Succinate Induces Apoptosis in Human Myelocytic Leukemla Cells
VINH HANG, . Department of Microbiology,
A potential permease involved in iron utilization by Vibrio
cholerae
KEITH M HARBER, Department of Computer Sciences,
Using SANE for Distributed Packet Routing in a Dynamically
Changing Network
JEREMY HIGHLEY, Department of Physics,
Construction and Refinement of a Transverse Electrical
Atmospheric Discharge
DARREN JOHNSON, Department of Chemistry and Biochemistry,
The Synthesis of New Two and Three-Dimensional Polypyrrolic Materials
SHEHZAAD KAKA, Department of Physics,
Consideration of Scintillating Fibers for use in High Energy
Physics
PIERRE S. KHREICHE, Department of Computer Sciences,
Internet Time Synchronization: The Network Time Protocol
(Version 3)
AMJAD-ALI KHOJA, Department of Zoology,
Screening, Mutational Analysis, and Identification of Profilin
Synthetic Lethal(psl) Mutations
SONALI KOLHATKAR, Department of Astronomy,
Identification of FIRST radio sources using an Object-Oriented
Approach
ALAN LYNN, Department of Physics,
Minimal Size Tokamak Design.
KURT MUEHLNER, Center for Nonlinear Dynamics,
Department of Physics,
Surface-Tension Driven Convection in a Liquid Bridge
JOE NEWMAN, Center for Nonlinear Dynamics,
Department of Physics,
An Event Driven Simulation of Vertically Vibrated Granular
Material
LORRAINE PELOSOF, Departments of Biology &
Chemistry and Biochemistry,
Hydrogen Bond Patterns in Crystals
FAKHRUDDIN RASHID, Department of Computer Sciences,
An Internet Platform
JENNIFER SOBECK, Department of Physics,
Characterization of the Basolateral K+ Channel in Necturus
Enterocytes
SCOTT A. STRATEMANN, Department of Microbiology,
Swarming in Salmonella typhimurium
ADAM URBACH, Department of Chemistry and Biochemistry,
A Novel Route to Synthesis of an Octapyrrolic Molecule
CHARLES WILLMORE, Department of Geological Sciences,
Topaz in a Seaquist Ranch Pegmatite, Mason, Texas
JUDDI YEH, Department of Zoology,
The Assessment of Actin Polymerization in Profilin Mutants
of Saccharomyces cerevisiae by a Fluorometric Assay
Hydrogen Bond Patterns in Crystals*. SRIRAM
BALA and LORRAINE PELOSOF . Departments of Biology & Chemistry
and Biochemistry, The University of Texas at Austin.- Our
study of hydrogen bond patterns has utilized graph-set methodology
to recognize, characterize and catalog common patterns among hydrogen
bonds. The specific pattern we have studied is an eight-membered
ring containing two hydrogen bond donors and two acceptors. The
eight-membered ring is made of two four-atom fragments which we
have classified according to bond orders and functional groups.
Among these functional groups, carboxylic acids have been examined
in detail, and have been found to participate in eight-membered
rings less frequently than expected. As a result, our study has
gone on to explore the other type of interactions involving carboxylic
acids. We plan to extend this analysis to include other functional
groups .
* Supported by Dr. Stanley Schultz, National Institute of Health
Grant- DK 45251-03
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Occurrence of Marine Radiaxial Calcite Through
Phanerozoic Time. JENNIFER L. BEALL and BRENDA L. KIRKLAND.
Department of Geological Sciences, The University of Texas
at Austin.-Radiaxial calcite is an unusual form of marine
calcite which varies in abundance through time. To test the hypothesis
that radiaxial calcite formation is related to global-scale temporal
changes, we surveyed 700 thin sections of carbonate rocks varying
in age. Radiaxial calcite is common in lower Paleozoic and Cretaceous
carbonates, correlating to times of high sea level, modeled high
PCO2, greenhouse conditions, and calcite seas. In contrast,
late Paleozoic occurrences in biolithite correspond to times of
low sea level, low PCO2, icehouse conditions, and aragonite
seas. The occurrence of radiaxial calcite does not parallel accepted
curves for fluctuations in global phenomena through Phanerozoic
time, suggesting that multiple factors acting globally and locally
may control formation of radiaxial calcite.
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A Study of Near-Infrared H2 Emission
in Planetary Nebulae. JAMES CRAWFORD and HARRIET DINERSTEIN.
Department of Astronomy, The University of Texas at Austin.-
We present results from a near-infrared spectroscopic survey of
planetary nebulae obtained at the University of Texas' McDonald
Observatory. Many of the objects display emission lines due to
excited vibrational levels of molecular hydrogen (H2).
Although planetary nebulae are generally regarded mainly as regions
of ionized gas, the H, emission indicates that some planetary
nebulae have more complicated structures, possessing neutral components
as well. The emission line intensities provide information about
the physical conditions and masses of these neutral components.
This research was supported by the National Science Foundation.
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RRR-alpha-Tocopheryl Succinate Induces Apoptosis
in Human Myelocytic Leukemla Cells. CASEY GREEN, BRITTNEY-SHEA
HERBERT, BOB G, SANDERS AND KIMBERLY KLINE. Genetics Institute,
University of Texas at Austin. -VES-induced apoptosis in human
myelocytic HL-6O leukemia cells was demonstrated by: detection
of chromatin condensation (12, 29 and 74% apoptosis after 1, 2
& 3 days treatment with 10 microgram/ml VES) in DAPI stained
cells; a pre-G1 apoptotic peak detected by flow cytometry of propidiurn
iodide stained cells; and gel electrophoretic detection of fragmented
DNA (DNA laddering). Analyses of apoptotic related factors c-myc
and bcl-2 showed VES-induced changes at the mRNA level; however,
protein changes were not observed.
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A potential permease involved in iron utilization
by Vibrio cholerae. VINH HANG, DEBORAH OCCHINO, and
SHELLEY PAYNE. Department of Microbiology, The University of
Texas at Austin.- Like most bacteria,Vibrio cholerae
requires an iron source. Iron, in the form of heme, enters the
cell by first binding to HutA, the outer membrane heme receptor.
Subsequent transport across the periplasmic space and cytoplasmic
membrane is presumed to require a series of specific binding proteins.
Five genes encoding proteins in this pathway have been characterized,
and a gene encoding a sixth possible heme transport protein has
recently been identified. The DNA fragment, encoding this protein,
was cloned into a plasmid vector and transformed into E.
coli cells. The nucleotide sequence of the gene was determined
through the Sanger dideoxy method. Using the BESTFIT program from
GCG, the DNA sequence was found to be homologous to the ATP binding
region of FhuC, which is another iron transport complex.
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Using SANE for Distributed Packet Routing
in a Dynamically Changing Network. KEITH M HARBER. Department
of Computer Sciences, The University of Texas at Austin.-
Packet routing in a dynamically changing network has spawned many
"solutions" in the networking community, and it forms
a challenging testbed for machine learning algorithms. When links
become defective in the network or when new links are added, the
policy has to be revised based on reinforcement feedback. I propose
using SANE (Symbiotic Adaptive Neuro-Evolution), a reinforcement
learning method by Moriarty and Miikkulainen (1995), to "evolve"
a neural network solution to this problem. The advantages of SANE
are its ability to form neural networks quickly in domains with
sparse reinforcement. The initial results on a discrete event
simulator are encouraging and suggest that the approach could
scale up well to more realistic networks.
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Construction and Refinement of a Transverse
Electrical Atmospheric Discharge*. JEREMY HIGHLEY. Department
of Physics, The University of Texas at Austin.- An existing
transverse electrical atmospheric (TEA) discharge has been retrofitted
into a large stainless steel chamber in preparation for doing
time resolved studies of molecular ions formed in a discharge
and for use as an excimer laser. Details of chamber construction,
discharge assembly mechanics, discharge electrical circuitry and
control electronics are presented. Results of preliminary studies
of discharge characteristics versus electrode spacings and voltages
are presented. Breakdown voltage of the free-running spark gap
versus pressure and other circuit voltages have been measured
versus time as a first step in improving the characteristics of
the discharge produced.
*Supported by The Welch Foundation and The U.S. Department of
Energy.
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The Synthesis of New Two and Three-Dimensional
Polypyrrolic Materials. DARREN JOHNSON. Department of Chemistry
and Biochemistry, The University of Texas at Austin.-- The
current interest in expanded porphyrins is stimulating considerable
effort devoted to the preparation of new polypyrrolic precursors.
In this presentation the synthesis of several new polypyrrolic
materials will be described. Efforts directed toward the synthesis
of a specific target will be presented. Finally, the potential
use of precursors as building blocks for the construction of novel
expanded porphyrins as the basis for preparing hitherto unknown
macrobicyclic ligands will be discussed.
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Consideration of Scintillating Fibers for use
in High Energy Physics. SHEHZAAD KAKA and JACK RITCHIE Department
of Physics, The University of Texas at Austin.- Scintillating
fibers have become increasingly utilized in frontier high energy
experiments. Reported here is a preliminary investigation into
the operating efficiency of scintillating fibers, focusing on
the optical attenuation length for scintillation within the fibers.
A method for measuring the attenuation length in a conventional
scintillator is described and applied with some variation to scintillating
fibers.
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Internet Time Synchronization: The Network
Time Protocol (Version 3). PIERRE S. KHREICHE. Department
of Computer Sciences, The University of Texas at Austin. -
Network Time Protocol (NTP) is widely developed in the Internet
to synchronize computer clocks to each other and to international
standard via telephone modem, radio and satellite. Most of the
estimated deployment of 100,000 NTP servers enjoy synchronization
to within a few tens of milliseconds in the Internet of today.
This paper describe the purpose of NTP, which is to convey timekeeping
from these servers to other time servers via the Internet and
also to cross-check and mitigate errors due to equipment or propagation
failures.
Furthermore, this document is emphasized to illustrate in details
how NTP is designed to provide three products: clock offset, roundtrip
delay and dispersion, all of which are relative to selected reference
clock. An overview of the NTP configuration is explained, including
its data format, how time and synchronization is determined, along
with a description of the algorithms and functional procedures
used to improve the accuracy of measurements made over Internet
paths.
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Screening, Mutational Analysis, and Identification
of Profilin Synthetic Lethal(psl) Mutations. AMJAD-ALI KHOJA,
YOUNGSEOK KWEON, and BRIAN HAARER. Department of Zoology, The
University of Texas at Austin - Asymmetrical cellular organization,
cell polarity, is fundamental to cellular morphogenesis during
the development of unicellular and multicellular organisms. A
highly conserved and a ubiquitous cytoskeletal protein, actin,
is known to play a pivotal role in maintaining cell polarity.
By exploring genetic interactions with a crucial actin-binding
protein, profilin, in the budding yeast, Saccharomyces cerevisiae,
we hope to identify other factors that assist actin in establishing
and maintaining cell polarity in response to intra- and extracellular
signaling. We have screened for profilin synthetic lethal (psl)
mutations that enhance the phenotypic effects of non-lethal profilin
mutations. From such genetic screenings using colony sectoring
assay, we have isolated several psl mutant alleles. Two of our
psl mutations are allelic with swi6, which we had
previously identified in psl screening. Recent data shows
that some of our new psl mutants may define previously uncharacterized
genes.
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Identification of FIRST radio sources using
an Object-Oriented Approach*. SONALI KOLHATKAR. Department
of Astronomy, The University of Texas at Austin - Dr. Hill
and I used the 0.8m telescope's Prime Focus Camera at McDonald
Observatory to extend the optical Texas Deep Sky Survey. We associated
radio sources from the FIRST survey, which is to be one of the
most comprehensive and sensitive radio surveys to date, with optical
objects from the TDSS. The algorithm used is a positional coincidence
method which sorts optical objects according to brightness and
computes probabilities of identification by iteration using image
densities and measurements errors. I coded the identification
method using the Object-Oriented language C++ in order to easily
manipulate radio and optical sources by treating them as variables
of defined classes.
* Supported by Dean Grant for Undergraduate Research, College
of Natural Sciences, University of Texas at Austin
.
1 Benn, C. R. Observatory, 103, 150 (1983).
2 Benn, C. R., Grueff, G., Vigotti, M., Wall. J. V. Monthly
Notices of the Royal Astronomical Society, 230, 1 (1988).
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Minimal Size Tokamak Design. ALAN LYNN.
Department of Physics, The University of Texas at Austin.-The
smallest tokamak power plant design must satisfy numerous physical
and economic constraints. The dependence of the reactor major
radius on neutron wall loading, plasma beta and beta=1 limits,
torodial field power, and net power output are considered here.
A simple limiting condition was found that embodies all the above
conditions. The result shows a unique minimum major radius exists
that will satisfy all the above constraints.
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Surface-Tension Driven Convection in a Liquid
Bridge*. KURT MUEHLNER, MICHAEL SCHATZ, HARRY L. SWMNEY. Center
for Nonlinear Dynamics, Department of Physics, The University
of Texas at Austin.- This flow, which models the essential
hydrodynamics of float-zone refining and crystal growth, presents
an excellent opportunity for applying dynamical systems concepts
to a technologically important problem. Using infrared imaging,
we are able for the first time to visualize the spatio-temporal
structure of the flow. For aspect and volume ratios near unity,
we present a sequence of images of the flow as the control parameter
(Marangoni number) is increased from the onset of time-dependence
to the appearance of chaos.
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An Event Driven Simulation of Vertically Vibrated
Granular Material. JOE NEWMAN, under the supervision of PAUL
UMBANHOWAR and HARRY SWINNEY, Center for Nonlinear Dynamics
and Department of Physics, The University of Texas at Austin.-
A recent discovery is that vertically vibrated granular media
can form standing wave patterns that oscillate at half the driving
frequency. To better study patterns, a computer simulation was
written to attempt to reproduce the patterns. This event driven
computer model simulates the system of particles by calculating
two-particle, inelastic collisions and only updates particle momentum
during collisions. Included in the algorithm is a scheme to partition
the system into subcells to improve the performance. This computer
model will give greater insight into the conditions necessary
for pattern formation and will aid researchers in determining
the underlying mechanisms.
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An Internet Platform1: FAKHRUDDIN
RASHID. Department of Computer Sciences, The University of
Texas at Austin. - This research simulates an internet platform
using a C++ program. The platform enables three functions at the
networking layer. First, it allows visualization of an internet
packet2 by showing a trace as that packet travels through
the internet. Second, it allows the development and testing of
improvements to the structure of the internet packet. Finally,
it gives a better understanding of the intermediate systems (subnets
and routers) with which an internet packet has to interact, in
order to get to the destination.
__________________________
1. The internet platform is the collection of computer
hardware and software that enables us to communicate electronically.
2. An internet packet, as used below, is the logical
data unit that gets transported on the internet and which carries
information. e.g. part of an E-mail message.
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Characterization of the Basolateral K+ Channel
in Necturus Enterocytes*. JENNIFER SOBECK. Department of
Physics, The University of Texas at Austin.- Standard electrophysiological
techniques and the relation I/V= sigma were utilized to measure
a channel conductance of 135 pS [in more familiar units 135 x
10-12 (mOhm)-1]. The known channel blocker
Leiurus quinquestriatus venom (LQV) was used to determine
the orientation of the channel. The channel was also found to
be voltage-gated.
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Swarming in Salmonella typhimurium.
SCOTT A. STRATEMANN. Department of Microbiology, The
University of Texas at Austin.-- Examination of the genetic
basis for the surface-specific form of bacterial motility called
swarming1 was facilitated by production of mutant cells
with a bacteriophage-borne transposon including an alkaline phosphatase
gene. Appropriate expression of the fusion proteins focused analysis
to genes expresssed around the periplasmic space, as chemotaxis
and flagellar systems were previously shown to be requisite for
swarming2. Results of the study implicate two sets
of genes, one involved in glucan synthesis and osmoregulation,
the other connected to assembly of the lipopolysaccharide of the
outer membrane, to be essential for differentiation of S. typhimurium
into swarm cells.
1 Harshey, R.M. (1994) Mol. Microbiol. 13, 389-394.
2 Harshey, R.M. & Matsuyama,T. (1994) Proc. Natl. Acad.
Sci. USA 91, 8631-8635.
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A Novel Route to Synthesis of an Octapyrrolic
Molecule. ADAM URBACH. Department of Chemistry and
Biochemistry, The University of Texas at Austin.-- The chemistry
of expanded porphyrins has made rapid progress recently due to
the development of host substrates for enatiomeric resolution
and of efficeint sensitizers for photodynamic therapy. Roasirn,
a hexapyrrolic expanded porphyrin, is easily prepared and provides
an exceptional synthetic system for the derivatization of chiral
and water-solubilizing groups. Presented here is the attempted
synthesis of two chiral rosarin molecules from precursors chosen
to confer specific functionality. Mass and UV/Vis spectral analyses
are in coincidence with previous rosarin literature. These analyses
suggest that not only rosarin is formed in the synthesis but also
an octpyrrolic macromolecule. If these analyses prove true, then
a novel route to the larger heterocycle has been found. Further
effort is being directed toward the complete synthesis and characterization
of the molecules.
*Supported by NASA.
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Topaz in a Seaquist Ranch Pegmatite, Mason,
Texas. CHARLES WILLMORE, and DR. D. SMITH. Department of
Geological Sciences, The University of Texas at Austin- A
pegmatite has been analyzed to investigate the origin of topaz,
the state gem of Texas. The Seaquist samples contain zinnwaldite
(Li-Fe-F mica), cassiterite, tourmaline, and an oxide of Nb plus
Ta. This assemblage shows little resemblance to a comparative
sample of typical Llano area pegmatite from near Kingsland, Tx.
Topaz has yet to be found in my samples from the Seaquist pegmatite,
but further sampling is likely to find topaz. The mineral assemblage
is similar to that of granites known to contain topaz, there are
significant occurrences of topaz in modern alluvium on the Seaquist
Ranch, and other area pegmatites are known to contain topaz. Analysis
by optical petrography and electron microprobe establishes the
unusual F-rich mica composition that may be a key to the genesis
of the topaz and the surrounding granite.
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The Assessment of Actin Polymerization in Profilin
Mutants of Saccharomyces cerevisiae by a Fluorometric Assay.
JUDDI YEH and BRIAN HAARER. Department of Zoology, The University
of Texas at Austin.- Actin, a major component of the cytoskeleton
of eukaryotic cells, polymerizes and depolymerizes under the control
of various signaling pathways and is mediated by a variety of
actin-binding proteins. Much that is known about the properties
of actin and associated proteins comes from studies of the budding
yeast S. cerevisiae which has only one actin encoding gene.
From in vitro studies, the actin-sequestering protein profilin
can function both to promote and inhibit the formation of filamentous
actin. Furthermore, profilin is implicated in signal transduction
pathways due its ability to interact with phosphatidylinositol
4,5-bisphosphate (PIP2) and with yeast adenylate cyclase.
Using a fluorometric assay to detect the amount of rhodamine-labeled
phalloidin bound to F-actin, we are examining the abilities of
various profilin mutant and overproducing strains to respond to
conditions that normally perturb the cellular F-actin concentration.
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