Student Abstracts


A

Ruben Alarcon Faculty Mentor: Dr. Harold Koopowitz

Population Genetics of Dudleya multicaulis: A Threatened Plant Endemic to Orange County

Dudleya multicaulis (Crassulaceae) is a threatened plant native to the coastal sage scrub community of Southern California. The specific habitat requirements, patchy distribution and low population numbers puts this species at risk of extinction. In this study we investigated the gene flow and genetic structure of eight geographically distinct populations located in Orange County by means of protein electrophoresis. Our preliminary results indicate that the populations may be genetically isolated from one another. This suggests that the genetic diversity of D. multicaulis will be maintained only if several populations are preserved.

Frank Joseph AlbertFaculty Mentor: Dr. Roger McWilliams

Electron Beam Diffusion

The experimental investigation of cross field electron beam spatial diffusion in a magnetized plasma is the subject of this presentation. The presence of an energetic electron beam in a plasma causes the creation of an instability, which then causes increased spatial and velocity diffusion as compared to the background plasma electrons. This instability is shown to be a function of the plasma density, electron beam density, and magnetic field. Experimental measurements show that the cross field spatial diffusion, of electrons from the injected electron beam, to be significantly greater than classical predictions for electrons in a plasma at around 2 m2/s. This discrepancy is accredited to the beam-plasma instability. Experiments were conducted in the Irvine Torus with typical plasma parameters of background pressure at 10-4 Torr, electron and ion density between 109 cm-3 and 1010 cm-3, electron temperature between 5 eV and 15 eV, i on temperature at 0.2 eV, and magnetic field between 0.25 kGauss and 1.5 kGauss. The dependence of electron diffusion as a function of magnetic field will be discussed.


Daniel Enrique Aldana Faculty Mentor: Dr. Caesar Sereseres

The Peace Process in Guatemala

In Guatemala, it is now estimated that more than 130,000 people have either been killed or disappeared since 1962. Shedding light over the peace process that has ended the longest civil war in Central American history requires substantial scrutiny. The peace process has been on-going since the late 1980’s and the final peace accord was signed in December 1996. Altogether, with assistance and support from United Nations officials, there have been eight separate peace agreements signed between the Guatemalan Government and the Guatemalan National Revolutionary Unity (URNG). The main focus of the project is to evaluate the implementation of the peace accords in order to address the questions of sustainability, government reform, costs, and verification. At the core of the project is a close examination of the peace accords. In particular, the ending of the conflict, the restructuring of Guatemalan society, politics, and the economy. The key to research will consist of a visit to Guatemala. Conducting field research in Guatemala will provide us with a more accurate account of the politics of the peace process in ending the war as well as rebuilding the post war society. In Guatemala, observations, interviews and information from local institutions could contribute significantly to this project. I’ve compiled a list of embassies, educational institutions, interest groups and non-governmental organizations in Guatemala that may also contribute information that will prove vital to the final report.

Catherine Allen Faculty Mentor: Dr. John Rowe

Ishmael Reed's Mumbo Jumbo and the Establishment of the Primacy of the Text in African-American Culture

Ishmael reed's Mumbo Jumbo is about the African-American literary tradition and its relation to western literature as a whole. Set during two self-conscious African-American literary movements, the Harlem Renaissance and the Black Arts Movement, Mumbo Jumbo becomes a response to the issues raised by these movements, especially the criticisms which the Black Arts Movement leveled at the African-American novel in general i.e. that it lacked performance capability, that it had to be political. Moreover, Reed incorporates several types of media into his novel: movies, music, art and photography. In doing so he underscores the appropriative power of literature while at the same time questioning the traditional view of the primacy of the oral tradition within the African-American culture.



B

Kristin Baczynski Faculty Mentor: Dr. Michael Scavio

A Qualitative Study on the Regulation of the Internet in Germany, Singapore, and the United States

In 1995, the International Data Group reported that 40 million people used the Internet in their home, school, or workplace. This rapidly growing popularity has caused many countries to attempt to regulate the Internet. This study will show the feasibility of Internet regulation through the examination of regulations and outcomes in three countries: the United States, Singapore, and Germany. All three countries have recently passed legislation that places government control over Internet content, and each country has seen varied reactions as a result. News reports and primary documentation from and about the United States, Singapore, and Germany were used to determine the content of the Internet regulations, their intents, and their effects on Internet usage in each country. In addition, brief electronic mail interviews were conducted with several experts on censorship and the Internet to gain an additional perspective. Data analysis is currently underway. The findings of this study are expected to re veal whether or not the regulation of the Internet by national governments is realistic and feasible.

Kaveh Badiei Faculty Mentor: Dr. J. Scherfig

Modeling of Temperature Changes in Wastewater Treatment Plants in Cold Weather Regions

Biological treatment processes, especially nitrification and denitrification, are very sensitive to temperature changes lower than 10°C. Short-term temperature changes occur frequently in many areas of the world, such as Northern Europe. To aid in the design and optimization of treatment plants, a dynamic model has been developed. The model predicts the hourly temperature in biological treatment tanks within 0.5°C over a1-month period when the hydraulic residence times range between 12 and 36 hours. Use of the model requires only the initial temperature and the hourly influent temperature. The major findings is that the temperature variation is very dependent on local wind conditions, which can be modified by windbreaks or (more expensively) by tank covers. The findings of this research project aims to improve the computer modeling of the local wind conditions. Furthermore, using several computer programs, temperature of the treatment tanks can be predicted within a reasonable accuracy.

Esmeralda Beas Faculty Mentor: Dr. Hemin Chin

Functional Analysis of the Neural-Restrictive Silence Element Binding Factor (NRSF) in the N-type Ca+2 Channel a1B Subunit Gene

Voltage-sensitive Ca2+ channels found in the plasma membranes of many excitable cells regulate calcium entry to mediate a wide variety of physiological functions, encompassing membrane excitability, enzyme regulation and gene expression in cell bodies, and neurotransmitter release from nerve terminals. The L-, T-, N-,P/Q- and R- Ca2+ channel types have been described based upon various studies. The skeletal muscle L-type Ca2+ channel, the first to be defined at the molecular level, is composed of multiple subunits, a1, a2-d, b and g and corresponding cDNAs have been cloned and sequenced. The cloned skeletal muscle a1 subunit, exhibits structural features common to voltage-gated cation channel gene families and is capable of directing expression of Ca2+ channel activity in heterologous expression systems. Homology screening resulted in the isolation of five additional a1 subunit cDNAs encoding either dihydropyridine (DHP)-sensitive L-type channels (a1C, & D) or DHP-insensitive high voltage-activated Ca2+ channels (a1A,B, & E). The a1D transcripts encoding DHP-sensitive L-type Ca2+ channels are present in a variety of excitable and nonexcitable cells including brain, neuroblastoma cells, pancreatic b-cells, and kidney. In contrast, the expression of the a1B mRNA encoding the w-conotoxin GVIA-sensitive N-type Ca2+ channel seems to be restricted to the CNS and neuronal cells. It is of interest to examine molecular mechanisms underlying the regulation of N-type Ca2+ channel a1B subunit gene expression and compare it with those involved in the L-type a1D subunit gene expression.

Nelsson H. Becerra II Faculty Mentor: Dr. Francisco J. Ayala

Who is Hitchhiking with Sod?

Around fifteen years ago, studies in intraspecific (for one single species), genetic polymorphism were underway at the DNA level. Since then, the most widely used model has been Drosophila melanogaster, the fruit fly. Several regions in the genome of this organism have been analyzed. Therefore, we know that polymorphic levels are different on distinct genome regions; although, we are beginning to know about the patterns of variation, and the evolutionary process that produced them. A region that has shown low levels of polymorphism has been the Sod (Superoxide dismutase) locus in Drosophila melanogaster. One of the possible explanations is that this locus had been "hitchhiked" in a recent evolutionary event. This means that a beneficial mutation at this gene, or one close to it, could be responsible for an increase of its carrier allele. The presented work will try to test this hypothesis by sequencing regions surrounding this locus. If the hitchhiking process proves to be true, it is expected that t he limits of this hitchhiked, low variable region will be found at a relatively close distance to Sod. The two areas studied are approximately fifteen kilobases away from both ends of the Sod gene. Our analysis has indicated the discovery of the upper limit, which seems to confirm the proposed hypothesis.

Bahare Behnia-Tehrani Faculty Mentor: Dr. Ronald A. Sherman

Maggot and Fly Immunogenicity

The goal of this investigation was to test the hypothesis that maggots, flies, and insectary dust contain antigens which can stimulate antibody production in humans. To test this hypothesis, we screened for IgG, IgA, and IgE in the serum of a long-time fly researcher, by western transfer immunoblotting of maggot, fly, and dust extracts.
Antigen Preparation: Phaenicia sericata was reared from our 6-year old colony.
Maggot Extract: Early 3rd instars were homogenized, mixed with 5% acetic acid (AcOH) and ether. The samples were defatted by repeated ether extraction’s. The resulting sample in AcOH was clarified, filtered, and dialyzed.
Fly Extract: Dead adults were crushed, dissolved in 5% AcOH, clarified, filtered, and dialyzed.
Insectary Dust: Air-born particles in the fly incubator, which settled in a pan of distilled water, were freeze-dried, re-suspended in 5% AcOH, clarified, and filtered. Serum was collected from the project sponsor, who had a 6-year exposure to the flies and maggots, as well as an atopic constitution. Control serum was donated by volunteer laboratory workers. When placed onto nitrocellulose, all crude extracts reacted to IgE, and IgG in the supervisor’s blood. Maggot, and fly extracts, western transferred demonstrated binding of IgG and IgA to 10,000d bands. We have demonstrated that both maggot and fly extracts contain molecules, probably proteins, which react with IgG and IgA in an exposed human. Although the specific nature of these antigens are not known, and their protective effect undefined, still our results suggest that a test for immunity may be feasible.

Felicia Bleecker Faculty Mentor: Dr. Salvatore Maddi

Personality Correlates of the Academic Elite: A Study of UC Irvine Professors

In a call for methodological pluralism, David Sears (1986) argues the biases in utilizing American college students as the overwhelming subject population of choice. In 1980, 75% of the articles in journals relied solely on undergraduates whereas only 15% dealt with content concerned with adults’ normal lives (Sears, 1986). Having often found the almost exclusive use of college students to be a valid concern of researchers, it appears necessary to dedicate my attention to population seldom studied in the past by psychologists. In an attempt to study an adult population as a student, it seems quite fitting to choose those held highest in intellectual regard in our society…the university professors. The upper echelon in the world of academia seems to remain unique with its own set of values and aspirations. As many of these secrets remain esoteric, it is my bold challenge to study the "studiers" and determine which personality correlates drive them to such intellectual greatness. Using a random cross-sec tion of anonymous UC Irvine professors, an attempt will be made to uncover the personality correlates which assist in the accomplishment of superior academic achievement. Through a general assessment of personality provided by the NEO Five Factor Inventory and the Personal Views Survey II, professors will then be compared to well established norms as well as to professors from other disciplines. Finally, personality will be examined as it relates to varying levels of success within the academic environment, specifically the number of publications and attainment of academic rank.

Amber Marie Bosin Faculty Mentor: Dr. Paul Hyman

Ileal Motility in Children

Ileal motility has been studied in adults but not in children. My aim was to analyze the patterns of ileal contractions in children. In 20 children who were not acutely ill (12 male; x 6yr; range, 2mo-15yr), perfused catheters with 4 to 8 recording sites 5 or 10 cm apart were positioned through ileostomies fashioned for clinical indicated reasons; intractable constipation in 5, Hirschsprung's disease in 8, distal anatomic obstruction in 2, and other in 5. The migrating motor complex (the physiological marker for neuromuscular integrity of the proximal small bowel) was absent; in 55 hr of fasting recording there was no phase 3. The most prominent features were clustered contractions 6-10/min. with a duration 20-120 sec. and an amplitude 20-80 mmHg, found in 16 children. Some clusters appeared isolated while others appeared to propagate. In 12 children there were giant migrating contractions, defined by amplitudes > 100mmHg and duration > 15 sec., propagating at rates of 3-6 cm/sec. over at least 20 cm. Fasting and postprandial features did not differ. There was no significant change in motility index for the hour following a meal. Although these studies were performed in children with anatomic or physiological colon disorders and through ileostomies, they provide a preliminary assessment of the qualitative features of ileal motility patterns in children.

C

Alyssa Kieu-Nuong Cao Faculty Mentor: Dr. Petra Wilder-Smith

CO2 Laser Tooth Whitening

The objective of this investigation was to achieve the optimal tooth bleaching outcome with the use of a heat-activated bleaching substance and a CO2 laser. A CO2 laser (Sharplan Lasers Inc., Alendale, NJ) was used in the continuous wave, pulsed and superpulsed modes, at energy densities of 2.5-5J/cm2, a prr of 1Hz and irradiation durations of 30s on enamel surfaces of coffee-stained extracted human teeth. Hydrogen peroxide at concentrations of 10-30%, +/-sodium perborate tetrahydrate were applied to the tooth surface directly prior to irradiation and an IR camera (Inframetrics 900, scan speed 60Hz) recorded the thermal events. The superpulse mode at an average power of 3.5W rapidly achieved the desired bleaching temperature of 46-60oC and maintained this plateau temperature without overheating the pulpal tooth structures. At these parameters, significant lightening of the coffee stains on the tooth enamel was achieved without damaging effects on tooth structure or thermal damage. Use of peroxide plus perborate tetrahydrate versus the use of peroxide alone is beneficial due to perborate’s ability to lessen the effect of peroxide tooth surface softening. Further studies are being conducted to optimize laser parameters with tooth bleaching agents. This study was supported by DOE grant DE903-91ER 61227, ONRN00014-90-0-0029, and NIH RR01192.

Wayne Chan Faculty Mentor: Dr. Michael Rose

The Effects of Laboratory Selection and Nutritional Manipulation on Patterns of Aging of Drosophila melanogaster

Manipulating nutrition affects the relationship between survival and reproduction in D. melanogaster. For example, high nutrition causes increased early fecundity and decreased longevity, compared to controls. Low nutrition causes decreased early fecundity and increased longevity. Similarly, when populations are selected for increased early fecundity, life span decreases. In this experiment, we test the effects of nutritional manipulation and laboratory selection on patterns of aging. To that end we created six groups of populations, all derived from a common ancestral population. These populations were selected for either early or late fecundity in environments where nutrition was manipulated. After 27 generations of laboratory selection, we assayed these populations for early fecundity and starvation resistance, in two nutritional environments, and longevity. These assays suggest that nutrition is a neutral factor in the evolution of early fecundity. However, there is a trend toward increased life span in most populations selected under high nutritional conditions. Moreover, starvation resistance is highly influenced by the nutritional environment, with populations selected under high nutritional conditions evolving greater starvation resistance.

Jason Chang Faculty Mentor: Dr. Petra Wilder-Smith

An Analysis of Thermal Events During HO:YAG Laser Irradiation of the Pulp Complex

The purpose of this investigation was twofold: 1. to evaluate thermal events and effects resulting from pulsed Ho:YAG laser irradiation @2.1 mm of the dental pulp, 2. to determine whether these effects within the pulp chamber can be adequately modeled using an empty pulp chamber and root canal. These determinations will provide a potential for identification of safe laser parameters for localized laser pulp surgery, whilst avoiding the problems posed by laboratory use of fresh pulpal tissues. In extracted human incisors and canines, standardized 3mm diameter pulpal access to the pulp chamber was prepared. Pulp surfaces or empty pulp chambers were irradiated using a standardized set-up with Ho:YAG laser at 1, 2, 3.5, 4.5 W at 5 and 12 Hz. Thermal events were recorded using K-type thermocouples: a) 2, 3mm lateral to the irradiation site on the posterior pulp chamber wall, b) 2, 3mm lateral to the irradiation site on pulp tissues. Temperature increases resulting from laser irradiation correlated positiv ely with power (p<0.01), PRR (p<0.01) and irradiation-duration (p<0.05). At 5 Hz, no significant difference was determined between empty and filled pulp chambers (Student’s t-test, p>0.05). At 12 Hz and powers>3.5 W, pulp chamber dentin became significantly hotter than pulpal tissue (p<0.05); this is primarily attributed to development of charring on the dentin surface at these parameters. In conclusion, pulp tissues or model must be present within the pulp chamber during laser irradiation to ensure clinical relevance of thermal measurements.

Chan C. Chao Faculty Mentor: Dr. Ronald E. Rasmussen

The Effects of Sodium Arsenite on Human Lymphoblastoid Proliferation

Human lymphoblastoid cells (HLC) exposed to different concentrations of sodium arsenite (SA) showed a dose dependent cytotoxicity, with 100% mortality at a concentration of 100 mM or higher. SA induced several proteins in a dose dependent manner, of which the most induced protein was heme oxygenase-1 (HO-1). Induction of HO-1 suggests that SA may cause oxidative stress by generation of reactive oxygen species. To test the oxidative stress hypothesis, cells were pretreated with the antioxidants DL-a-tocopherol (Vitamin E) at 1 mM for 24 hours and ascorbic acid (Vitamin C) at 10 mM for 24 hours. Both antioxidants did confer some protection at 0.1 mM and 1 mM SA concentrations. Cytotoxicity was reduced by 16%-17% in the pretreated cells. In another experiment, cells pretreated with a low concentration of SA (0.1 mM) for 24 hours to induce HO-1 were more resistant in 1 mM SA than untreated cells, showing a 19% reduction in cytotoxicity. Although pretreatment of the cells with Vitamin E and Vitamin C, an d at a low SA concentration did yield some protection for the cells when the SA concentrations were 0.1 mM and 1 mM, the treatments did not significantly reduce cytotoxicity at 10 mM or higher SA concentration. Oxidative stress appears to be a mechanism of cytotoxicity of arsenite.

Yen Phi Chau Faculty Mentor: Dr. Michael Rose

Differentiation of Allele Frequencies in Drosophila melanogaster Selected for Starvation Resistance

Drosophila melanogaster selected for postponed aging have shown enhanced resistance to stresses such as starvation and desiccation. Gene loci that encode metabolic enzymes are expected to be the loci at which allele frequencies change in response to this selection. Previous enzyme electrophoretic assays have determined allozyme frequencies of starvation-selected Drosophila melanogaster after more than 50 generations. New starvation resistant populations have been derived with the purpose of assaying allozyme frequencies earlier in selection. Allele frequencies at three different enzyme loci were examined in five-fold replicated outbred Drosophila melanogaster populations. Flies which previously had undergone selection for postponed aging were put under starvation stress or served as fed controls. One dimensional starch gel electrophoresis was used to determine the frequencies of the allozymes. There was a significant increase in the frequency of the slow allele encoding phosphoglucomutase after 15 ge nerations of selection. There were no significant differences in allele frequencies of alpha-glycerol-3-phosphate dehydrogenase and Cu, Zn-superoxide dismutase. It is expected that allelic differentiation would become statistically significant with continued starvation selection.

David Chia-Chang Chen Faculty Mentor: Dr. Sue Duckles

Postjunctional a2- Adrenergic Receptors in the Rat Tail Artery: Effect of Gender

To investigate possible gender-related differences in the vasoconstrictor responses to activation of postjunctional a2-adrenergic receptors in the tail arteries of male and female Fischer-344 rats, isolated ring segments were used. In both male and female animals, norepinephrine concentration response curves were significantly shifted to the right in the presence of a2-adrenoceptor antagonists idazoxan (300 nM) or rauwolscine (50 nM). This antagonist inhibition of vasoconstrictor response was significantly greater in arteries from male compared to female rats. Furthermore, the presence of the a2-adrenoceptor agonist UK-14304 (300 nM) significantly enhanced the vasoconstrictor response of both male and female animals to the selective a1-adrenoceptor agonist, methoxamine. Gender-related differences were also observed in this agonist potentiation of the methoxamine response curve with male arteries having a slightly greater response than female. These findings suggest that the function of postjunctional a2-adre noceptors is influenced by differences relating to gender. Gonadectomy was performed to determine the role of gonadal hormones in producing these gender-related differences. Although male-female differences were maintained, the removal of sex hormones in either males or females did not alter vascular response to either agonists or antagonists of a2 adrenergic receptors. These findings suggest that these sex differences in a2 adrenergic receptor function are not maintained by either male or female gonadal steroid hormones but may be developmentally regulated.

Samuel Young Choi Faculty Mentor: Dr. Petra Wilder-Smith

Microleakage in Dental Restorations After Drill and Laser Preparation

Microleakage is the chief cause of dental restorative failure. The aim of this investigation was to determine the effects of Er:YAG laser irradiation on microleakage of glass ionomer cement (GIC) restorations. Conventional Class V cavities prepared in 117 extracted human teeth: (a) 15 teeth underwent conventional preparation with a high speed drill. (b) 54 teeth underwent conventional preparation with a high speed drill followed by laser surface treatment at 10 mJ/pulse. These teeth were subdivided into three subgroups: In group 1, 18 teeth were exposed to the laser treatment for 2 seconds receiving 250 mJ/cm2. In group 2, 18 teeth were exposed to the laser treatment for 3 seconds receiving 375 mJ/cm2. In group 3, 18 teeth were exposed to the laser treatment for 4 seconds receiving 500 mJ/cm2. (c) 48 teeth underwent full cavity preparation using the laser at these parameters: 16 teeth were treated at 30 mJ/pulse, 16 teeth were treated at 40 mJ/pulse, and 16 teeth were treated at 50 mJ/pulse. Mi croleakage measurements were performed by immersing all samples in a 5% solution of methylene blue between 12 to 24 hours. Then teeth were bisected and dye penetration was measured under the light microscope. Regression analysis associated laser treatment with improved treatment outcome but greater treatment variability (p<0.1). Laser parameters and protocol were identified as secondary determinants for treatment outcome (p<0.05). This project demonstrates the potential for Er:YAG laser applications in restorative dentistry. Further studies are required to optimize parameters and protocol. This study was supported by DOE grant DE903-91ER 61227, ONR N00014-90-0-0029, and NIH RR01192. I would also like to give my thanks to Coherent for lending me their laser for this study.

Michael Chung Faculty Mentor: Dr. Christopher Grayce

Effects of Solvation on Model Semiflexible Polymers

We investigate the effects of solvation by simple repulsive solvents on the conformation of semiflexible model pearl-necklace polymers. The dependence of conformational measures such the probability distribution of squared end-to-end distance is calculated for a variety of solvation conditions and backbone stiffnesses, and some unusual effects are observed. For example, it appears possible that a sufficiently stiff polymer may actually become larger when removed from the vacuum and placed in a purely repulsive solvent. Calculation are made both by direct Monte-Carlo computer simulation and simulation of the single chain in a new "scaled-particle theory" solvent influence functional.

Christine Marie Currie Faculty Mentor: Dr. Roxane Silver

Projecting the Futures of Middle-Aged Women

A sample of 364 middle-aged women (35-50 years) completed an anonymous survey regarding their lifestyle choices. They were asked to recall significant past events and to project future events and to record them on two timelines. The survey also included measures of life satisfaction, regrets and achievements. It was hypothesized that judgments regarding areas such as success in romantic relationships and career, desire for life to be different, and significant past life events would be associated with projections for one’s future. All of these areas seem to be associated with expectations of future life events. There was a positive correlation between judgments of past success in romantic relationships and length of the time horizon for future events. There was no such relationship between future projections and judgments of past success in career or child rearing. Results also indicate that women who experience negative affect regarding their fantasies of an alternate life projected fewer events for their future. Although the majority of women noted their first significant past event during their early lives, a notable portion of the sample did not report such events until much later. Results indicate that as the length of the time between birth and the first reported event increased, the number of projected future events as well as the length of the time horizon between the present and furthest future event decreased. These results imply that past experiences strongly influence expectations of future life. Future research should examine possible interventions that may lessen the impact of negative past life events on projections of the future.