Abstracts for the 2004 Joint Science
Symposium for Student Research







Abstracts from the Department of Biology

The effect of high concentrations of GA3 and seed age on
germination of Silene latifolia.

Allison Amore, Meredith Harry, William Wood

We investigated whether GA3 affected mean fraction germination of white campion (Silene latifolia) and whether seed age affected germination and/or responses to GA3. Four GA3 treatments (dH20, 2.601 x 10-3 M GA3, 1.170 x 10-2 M GA3, 2.601 x 10-2 M GA3) were applied to two ages of white campion seeds (2002, 2003). Five replicates per GA3 treatment per year with 50 seeds per replicate were used. GA3 treatment increased the mean fraction germination as compared to the control (p<0.0001). More seeds from the 2003 harvest were viable than the 2002 harvest. GA3 significantly effected the mean fraction germination of seeds as a fraction of viable seeds (p<0.0001) relative to the deionized water control. Mean germination as a fraction of viable seeds did not vary significantly among the three treatments that contained GA3. It appears that GA3 overcame the after-ripening requirement of the 2003 seeds. In conclusion, we found that GA3 increases the mean fraction germination of seeds as compared to the control and that seed age does play a role in the mean fraction germination of the seeds.

Genetic control of mitochondrial aggregation during Drosophila spermatogenesis: characterization of an nmd candidate gene

Sarah E. Baxley, Amanda C. Aldridge, Sean T. Burke, and Karen G. Hales

The no mitochondrial derivative (nmd) gene product is required for proper mitochondrial aggregation both on the spindle during meiosis and beside the nucleus in post-meiotic spermatids. The original nmd allele was associated with a P-element whose removal was associated with phenotype reversion and whose in situ map position (N. Wolf and M.T. Fuller, unpublished data) matched the recombination map position. By inverse PCR we characterized DNA flanking the P element insertion site and determined that the nmd P element is inserted in the 5' UTR of a previously uncharacterized predicted gene. Wild type genomic DNA encompassing this candidate gene was cloned into pCaSpeR4, and embryos were injected with the appropriate DNA mixture to create transgenic flies containing a wild type copy of the nmd candidate. Introduction of the transgene into a nmdmutant background resulted in fertile flies with normal sperm morphology, indicating that the nmd candidate can indeed rescue the mutant phenotype.

Assessing the prevalence of smoking and cocaine use among women with placental abruption in the Charlotte area in 2002

Melissa Breedlove, Davidson College
Dr. Tom Stubbs, CMC OB/GYN

In this retrospective chart review, we attempted to examine the rates of cocaine and tobacco use among women with placental abruption at Carolinas Medical Center in Charlotte, NC. Abruptio placenta is a well-documented pregnancy complication of maternal smoking and/or cocaine use, and can lead to a variety of further complications, from maternal or fetal distress and premature birth to fetal death. Because tobacco and cocaine use are preventable risk factors for placental abruption, they are of particular clinical interest. In this study, charts of women who were diagnosed in 2002 with abruptio placentae and treated by CMC OB/GYN staff were examined. Along with clinical data, maternal cocaine and tobacco use were recorded as indicated by self-report, and by urine drug screens when available. Out of a sample of 51 women, five (9.80%) were confirmed cocaine users and sixteen (31.37%) were smokers. Clinical outcomes of infants did not markedly differ between cocaine/tobacco users and non-users, although higher rates of Caesarean section and slightly longer hospital stays were observed among tobacco and cocaine users. African-American women were most likely to have been screened for drug use, while Hispanic women were least likely to have a urine drug screen. All five of the confirmed cocaine users and eleven (68.75%) of the tobacco users were screened for drug use. However, the overall drug screening rate was only 35.29% in our study sample. Because of underreporting, the rates of tobacco and cocaine use obtained in this study are likely to be underestimates.

The effects of seed age on viability, germination, and growth in
white campion (Silene latifolia).

Sarah Budischak, Patricia Peroni, and Jonathan Ripperton

In order to assess the lifespan of seed banks and the relative contribution of older seeds to future generations, the effects of seed age on viability and growth were examined in white campion (Silene latifolia). Seeds were collected over a span of 10 years from four different populations then stored dry in the lab. Germination trials were conducted in a growth chamber, and germination rate, percent germination, and percent viability were quantified. Seedling performance was determined in a greenhouse study that compared growth (leaf size) and phenology among seedlings that germinated from seeds of different ages. Significant trends for decreased viability and delayed germination in older seeds were evident in all populations. Seedlings from older seeds took significantly longer to reach developmental stages and had decreased leaf size relative to seedlings that emerged from younger seeds. Seedlings from older seeds appeared to be less robust and grow more slowly than those from younger seeds. Although seeds may remain intact in seed banks for many years, decreased viability and lowered seedling quality may reduce the actual contribution that older seeds make to future gene pools.

Bottom-up effects on processing chains in treehole communities

John Burkhart and Chris Paradise

The composition of insect communities in treeholes is limited in large part by resources. The primary resource of temperate treeholes is leaf litter, which exists along a continuum of decay and particle size. Different insects specialize on leaf litter in particular states of decay. Scirtid beetles may facilitate other insects through a processing chain interaction, in which their shredding of litter changes it for consumption by filter-feeding and grazing dipteran larvae. By altering resource condition, we hypothesize that scirtids influence community structure (abundance and species richness of the insect community). In a short preliminary experiment in 2003 and in long-term experiments set up in 2003 and early 2004, we examine the effects of scirtid densities and resource levels in mesocosms and natural treeholes. In all experiments, leaf litter and scirtid densities were or will be manipulated in crossed designs. Results from the 2003 experiment and designs for long-term experiments will be presented. In the short-term study, although mosquitoes colonized beetle-free mesocosms earlier, their growth was enhanced in the presence of beetles. There were no short-term effects on litter decay or species richness, although we hypothesize effects will occur in longer-term experiments. Supported by NSF grant DEB-0315208 to CP.

Nest depredation in suburbia: effects of predator guards, effects on bluebirds

Morgan Check, Sarah Hatfield and Mark Stanback

We examined nest success and clutch size in eastern bluebirds (Sialia sialis) nesting in “safe” and “unsafe” cavities on golf courses near Davidson, NC. From 1999-2001, all nestboxes were tree-mounted, allowing us to assess rates of depredation on vulnerable nests. Depredation at the egg and chick stages was roughly equivalent, as was depredation by mammals and snakes. In 2002, half of the nestboxes on each course were transferred to metal poles with stovepipe-style predator guards. Predator guards had a dramatic effect on nest success. Predator guards also had a significant effect on clutch size, with females laying smaller clutches in vulnerable nestboxes (independent of nest date effects). This represents the first experimental demonstration that birds can adjust their clutch size in response to perceived vulnerability.

Assessing the use of unmodified 40-mer oligonucleotides
in barcode microarray technology.

Danielle Hyun-jin Choi

Molecular barcodes (TAGs) have been employed in large scale yeast gene deletion studies. The researchers have used commercially produced microarray chips that synthesize barcode oligonuleotides on the surface of the glass slide, such as GeneChip® arrays (Affymetrix, Inc.) in previous studies (Winzeler et al., 1999). However, using unmodified oligonucleotides as the printing material on microarrays has not been common. We present a pilot study that uses 96 samples of unmodified 40-mer oligonucleotides as the printing material on the slides. The hybridization probes consisted of two identical preparations that differed only in their label, so the Cy5/Cy3 ratios were expected to be close to 1. Two different image analysis programs, Scanalyze (Michael Eisen, Stanford) and MAGIC Tool (Davidson College), were used to produce the ratio data. The observed ratios were generally lower than the expected ratio of 1, due to weaker signal in Cy5. Although further studies are required to determine the optimal probe to buffer concentrations and the incubation temperature, the signals obtained from the spotted oligos in this study seem sensitive and strong enough to generate quality ratio data.

The effect of 180 rotation on Xenopus laevis dorsal-ventral axis development

Erin Cobain and Kimberly Newton

Xenopus laevis has long been a popular vertebrate model for studying the specification and establishment of body axes and pattern formation during embryonic development. Many research groups have established fate maps of Xenopus laevis by staining specific cells in the early embryo and tracing the location of the stain during the course of development. In our experiment, individual blastomeres, at the two-cell stage, were injected with the fluorescent label rhodamine dextran. Then at the thirty two-cell stage approximately half of the embryos were rotated 180? for five hours to see if such a change in embryo position might influence cell fates. We allowed the embryos to grow to stage 33 and viewed them with fluorescence microscopy to determine what tissue types were labeled with rhodamine dextran. Analysis of the data indicated that rotation affected dorsal-ventral axis formation, as evidenced by differential fluorescent patterns between tadpoles that were rotated and those that remained in their natural position.

Malathion Causes Earlier Hatching and Stunted Growth in Developing Zebrafish, Danio rerio

Leslie Cook, Christopher Paradise, and Barbara Lom

While pesticides are used to minimize the insect damage to crops, many pesticides also exert detrimental effects on non-target organisms. Malathion is an organophosphorus pesticide widely used to control mosquitoes in urban areas and pests such as boll weevils in agricultural areas. Zebrafish, Danio rerio, are model organisms for developmental and genetic research because they are readily available, freshwater fish that produce large numbers of embryos. Zebrafish are sensitive to environmental changes, also making them a good model vertebrate for testing pesticide toxicity. Previous research examining non-lethal effects of malathion on adult zebrafish revealed that malathion causes skeletal deformities, enhances egg resorption into the ovaries, decreases hepatic cell number, and reduces cellular levels of nuclei acids, amino acids, and proteins. The non-lethal effects of malathion on developing zebrafish embryos, however, have not previously been quantitatively analyzed. By exposing zebrafish embryos to non-lethal doses of malathion, the teratogenic effects of malathion can be determined. I exposed zebrafish embryos to sub-lethal malathion concentrations to determine malathion’s effects on a developing vertebrate. Zebrafish exposed to 0.5-1.5 mg/L malathion consistently elicited more rapid hatching from the chorion than higher 2.0-3.0 mg/L malathion treatments, while the 2.0-3.0 mg/L malathion exposed zebrafish had significantly shorter body length and eye diameters, indicating that malathion has teratogenic effects on zebrafish embryos. Malathion’s action as an acetylcholinesterase inhibitor and the toxicity of the metabolites of malathion are likely responsible for the teratogenic effects of malathion on fish development.

Xenopus laevis retinal ganglion cell axon extension and targeting is independent of epidermal growth factor receptor and platelet derived growth factor receptor activity

Rob Gould and Barbara Lom

Retinal ganglion cells (RGCs) form the sole connection between the retina and brain. Growth factors participate in multiple aspects of RGC development including dendritic arborization in the retina and axon extension and arborization in the brain. This pharmacological study examined the influence inhibiting two growth factor receptors on Xenopus RGC axonal development in vivo. Platelet-derived growth factor receptor (PDGFR) signaling was inhibited by AG1295 and epidermal growth factor receptor (EGFR) signaling was inhibited by PD153035. Each inhibitor was applied to the exposed brain of Xenopus tadpoles during RGC axon extension and targeting. RGC axon trajectories were then visualized by horseradish peroxidase anterograde labeling and trajectory lengths, widths, and areas were analyzed digitally. Inhibition of neither PDGFRs nor EGFRs altered RGC extension or target recognition as compared to controls. This study demonstrated no significant effects of EGFR or PDGFR signaling on axonal extension or targeting. Thus, it is unlikely that PDGFR or EGFR signaling play significant roles in Xenopus RGC axon extension or targeting. Supported by NSF, Davidson College, and the Whitehall Foundation.

Short-term exposure to sub-lethal doses of malathion does not affect zebrafish (Danio rerio) development or acetylcholinesterase expression

Sarah N. Davis & Barbara Lom

Organophosphorus pesticides are acetylcholinesterase (AChE) inihibitors that are some of the most popular insecticides because of their rapid biodegradability and non-persistent nature. Malathion is the most widely used of these pesticides and is used primarily in boll weevil eradication and mosquito control. Pesticides such as malathion can often have undesired effects on non-target organisms such as amphibian and fish embryos. Previous studies have shown that long-term exposure to malathion in zebrafish (Danio rerio) causes a decrease in the hepatic-cell count, pathological changes in the ovary, skeletal deformities, decreased length and eye diameter, yolk sac edema, and earlier hatching. The purpose of this study was to determine if zebrafish have a 24-hour sensitive period to malathion during the first 96 hours of development and to visualize AChE activity in pesticide-treated embryos. Because both developing neurons and muscles use AChE activity, it was expected that zebrafish embryonic morphology could be affected by exposure to malathion at different periods of development. Early-stage zebrafish embryos (4-16 cells) were exposed to a sub-lethal concentration of malathion (2.5 mg/L) or to one of two controls (either tank water or a vehicle control containing acetone) for one of four 24-hour periods (0-24, 24-48, 48-72, or 72-96 hours after fertilization). The fixed 96-hour-old hatchlings were sliced into 20 ?m cross-sections and this tissue was stained for AChE activity using an adapted version of Naik’s staining procedure. No morphological differences were observed between malathion-exposed and control fish with respect to overall anterior-posterior length, gut area, eye diameter, dorsal-ventral length, or hatching time. In addition, tissue stained for AChE activity from the malathion-treated zebrafish did not appear noticeably different from tissue stained from either control. These results suggest that short-term exposure to sub-lethal doses of malathion does not greatly affect zebrafish development or AChE activity.

Relationship between resource use and environmental studies curricula at southeast US colleges

Caroline Hartridge and Chris Paradise

Educational experiences and learned behaviors related to the environment and sustainability are likely to be related to conservation of resources. The purpose of this project is to gather data on the resource use, mainly water and energy, of Davidson College and other similar schools within the southeast and relate those data to the respective school’s environmentally-related curricular offerings. Specifically the study is looking at variables such as the number of environmentally themed courses, the number of students enrolled per year per course, and whether the school offers a minor, major, or concentration in environmental studies. Resource use in the form of electricity, water, and natural gas, will be estimated for residence halls on each campus. A survey of juniors at each institution will be used to relate individual resource use and recycling practices with the number of environmentally-themed courses taken by that individual. The goal is to draw correlations between resource use and environmental awareness on the campuses and determine if there is a relationship between strong environmental curricula and reduced resource use.

Mometasone Furoate monohydrate and Rhinocort Aqua affect length, gut area, spine width, and mortality in Xenopus laevis embryos.

Joy Hester and Kate Williams

Nasonex ® (mometasone furoate monohydrate) and Rhinocort Aqua ® (budesonide) are both anti-inflammatory synthetic corticosteroids used to treat allergic rhinitis. Both of this nasal sprays are commonly prescribed to pregnant women when they suffer from hormonal persistent rhinitis. In high concentrations, Mometasone furoate and budesonide are reported to have different teratogenic effects in rodents. Because of these deleterious effects in other mammals, and the lack of conclusive studies performed in humans, more research should be done to determine the risks of these substances to developing embryos. To test the effects of these substances on developing Xenopus laevis embyros, four different concentrations of each nasal spray were tested in two different trails. For each of the two trials, 20 Stage 10 Xenopus laevis embyros were introduced to each of the solutions containing 50, 100, 150, or 200 microliters of 4.5 pH Steinburg’s, mometasone furoate monohydrate, or budesonide. The embryos were allowed to grow in the solutions for 72 hours and mortality was recorded daily for all conditions. At stage 40, all embryos were then fixed in 4% gluderaldehyde. The length, gut area, spine width, and general mutations were measured using Image J and the average of the measurements for each of the solutions for both trials were determined.

Habitat utilization by Black Rat Snakes (Elaphe obsoleta)

E. Pierson Hill, William J. Johnson, Michael E. Dorcas

Black Rat Snakes (Elaphe obsoleta) can be found throughout the eastern and central United States. Within this wide range, many populations experience varying degrees of habitat fragmentation due to human development. Such habitat destruction often leads to an increase in “edge” habitats where intact and disturbed areas come in contact. Over the course of 2 years, we tracked the movements of 13 rat snakes on the Davidson College Ecological Preserve, in Davidson, NC, which has numerous anthropogenically created “edge” habitats. “Edge” habitat may be favorable for rat snakes because it often has higher abundances of prey, such as rodents and nesting birds, compared to intact forest. “Edge” habitat may also provide more basking sites for thermoregulatory behavior while easily allowing snakes to seek cover when necessary. We found that, in general, rat snakes used open habitats more than forest habitats. During the active season (April – October), habitat use patterns were similar for males and females. In the winter, males were much more likely to be in open habitats while females spent more time in the interior of the forest. Although only approximately 20% of snake locations were located in edge habitat, approximately 60% of locations were within 30m of edge habitat. Our study provides the beginnings of an understanding of the habitat use of rat snakes in the southeastern United States and may allow evaluation of the impact of human development on this species.

Characterization of the subcellular localization of the nmd gene product in Drosophila spermatids

Sara H. Holmberg, Amanda C. Aldridge, and Karen G. Hales

We are investigating the subcellular localization of the product of the no mitochondrial derivative (nmd) gene, which is required for mitochondria to aggregate properly during different stages of spermatogenesis. We previously identified a candidate gene for nmd through inverse PCR of genomic DNA from the nmd mutant strain (S.T. Burke, N. Wolf, M.T. Fuller, and K.G. Hales, unpublished results). The product of the nmd candidate gene is a putative member of the AAA ATPase superfamily, and based on comparisons with homologs in other organisms, Nmd is predicted to reside on the outer mitochondrial membrane. To determine whether the nmd gene product is associated with spermatid mitochondria as predicted, we created an Nmd-specific polyclonal antibody for use in immunofluorescence experiments on fixed testis preparations. We report results of our experiments to determine the subcellular localization of the nmd gene product in testes from wild type and homozygous mutant males.

Online Identification System of North Carolina Snakes: a Novel Approach

Yurii Kornilev, Kiril Simov, Mur Muchane, and Michael Dorcas

Many conservation projects require the ability to accurately identify local flora and fauna (e.g., trees, frogs, flowers). Additionally, the non-scientific community is also interested in the proper recognition of various species they observe. Unfortunately, lengthy and expensive training is often required before identification skills can be considered reliable. Standard field guides and dichotomous keys, the traditional methods utilized for identifying species of animals and plants, usually necessitate knowledge of characters and term that are difficult to ascertain correctly without extensive prior experience and equipment. Often, difficult or hazardous capture and handling of the specimens are also needed for comparing characteristics. Therefore, we have developed a web-page that uses “Active Server Pages” (ASP) to query a database we compiled of generic characters of the location, behavior, coloration, etc. of the 37 snakes found throughout North Carolina. The user needs only to enter the information that they are certain about and the output lists all species that match the input criteria, plus pictures and brief information to help narrow down the choices. The output is linked to the Amphibians and Reptiles of North Carolina webpage* that describes the selected species in more details and enables the final identification. * http://www.herpsofnc.org/

Identification of potential GCP-170 receptors: Confirmation of plasmid insert and transformation into S.cerevisiae.

Robert Neuman and Karen Bernd

Golgins are a family of proteins associated with the Golgi apparatus. All have a globular N-terminal head and a C-terminal coiled coil domain which in some instances interacts with members of the Rab and Arl families of GTPase proteins. Some Golgins have been implicated in tethering membranes to each other and to cytoskeletal components, but the function GCP-170 / golgin-160 has not been thoughly studied. GCP-170 is a Golgi membrane protein suspected to be involved in Golgi membrane trafficking. We plan to use a yeast two-hybrid screen to identify potential ‘receptor’ proteins. DNA encoding the N-terminus of GCP-170 was inserted into a pLexA plasmid and then transformed into an E.coli vector. We worked to confirm the insertion of GCP-170 DNA into the plasmid contained within the transformants and to transform S.cerevisiae cells with a plasmid known to contain GCP-170 insert. The screening process began with whole colony PCR of E. coli transformants with. Plasmid DNA was isolated from colonies displaying bands consistent with GCP-170 and analyzed by digest and PCR to confirm insert presence. Digest screening was unproductive, failing to produce bands consistent with GCP-170. More sensitive PCR screening was frustrated by contamination of primer stocks, but upon receipt of new primers revealed evidence of GCP-170 insert in all of the colonies identified by the initial colony PCR screening. Yeast transformation has yielded transformants.

Effects of seasonal and meteorological variables and fence orientation on amphibian capture in terrestrial drift fences

Christopher J. Thawley, William J. Johnson, and Michael E. Dorcas

Drift fences are a commonly used technique to sample reptile and amphibian populations in a variety of habitats including forests and wetlands. Drift fences force individuals moving through a habitat to alter their trajectory to follow a fenceline set with pitfall traps. The objective of this study was to determine if weather, season, and fence orientation can affect quantity and species composition of amphibian captures in the drift fence. Two drift fences were opened on the Davidson College Ecological Preserve (DCEP) in the spring of 1999, and these fences were open for eight seasons (five spring and three fall). While open, students checked the fences each day for amphibians, and environmental variables such as rainfall and min/max/current temperature were also recorded. Drift fences were found to be capable of capturing a very high percentage of diverse amphibians species present in an area (15 out of 16 species known to exist on the DCEP). The drift fences also caught distinctly different subsets of the amphibian fauna depending on season. While movements of all species remain relatively constant between seasons, different genera display distinct seasonal movement patterns possibly in relation to the nearest water source, a small stream. Additionally, capture rates and the presumed terrestrial activity level of amphibians are positively associated with rainfall. These findings suggest that drift fences can detect differences in amphibian activity associated with seasonal, meteorological and directional variables.

Seed predators prefer Quercus alba acorns over Quercus phellos acorns in a mixed pine-hardwood forest.

Christopher J. Thawley, Kimberly Newton, and Monica Slinkard.

Trays of white oak (Quercus alba) and willow oak (Quercus phellos) acorns were placed in a North Carolina Central Piedmont mixed pine-hardwood forest and acorn disappearance was quantified. In each of five experimental blocks, four different treatments were established to test for effects of density and pure vs. mixed stands of acorns on predation. A marked and significant community-wide preference for white oak acorns over willow oak acorns was found regardless of seed density or mixed vs. pure stand. We also detected significant block effects, which suggest that location affects acorn predation. Results of previous studies also indicate an apparent preference for white oak acorns and suggest that this preference is based on lower tannin content typical of white oak acorns as opposed to higher tannins in acorns of the red oak group. Newer evidence in combination with results from this study suggests that predators preferentially consume white oak acorns as a means of utilizing a perishable food source. Although willow oak acorns lie dormant until spring, white oak acorns represent a use-or-lose resource, typically sprouting and becoming unpalatable within a few weeks following seed drop.

Imaging Xenopus laevis retinal neurite extension in vitro

Rebecca Thomason, Sheena Bossie, Sarah Tyndall, and Barbara Lom

Retinal ganglion cells (RGCs) form the sole connection between the vertebrate eye and brain. RGC development in Xenopus tadpoles has been well documented and provides an excellent model system to study axon outgrowth, navigation, and innervation both in vivo and in vitro. In vivo, RGC axonal growth cones actively navigate through the brain toward their target in the midbrain using environmental cues, such as fibroblast growth factors (FGFs). FGF is expressed in the Xenopus optic tract, and RGC growth cones express FGF receptors. RGC axonal growth cones stop advancing when they reach the tectum and start synapsing with tectal neuron dendrites. Our study examined retinal neurite extension rates in vitro in the presence and absence of FGF2. Eye buds were removed from stage 25-30 embryos and cultured as explants for 36-190 hours. Growth cone dynamics were recorded with a time-lapse digital camera attached to an inverted phase contrast microscope. Time-lapse movies were then analyzed to determine neurite extension rates before and during FGF2 application. We found that retinal neurite extension rates were enhanced by FGF2. To determine the proportion of neurites that represent RGCs, we also immunostained the retinal cultures with an RGC-specific antibody (3A10) and found that both 3A10+ neurites (RGCs) and 3A10- neurites extend growth cones from explanted Xenopus eyebuds.

Living with AIDS

Alex Trzebucki

HIV/AIDS ingrained itself into the worldwide cultural consciousness more quickly than any other disease. In the 23 years since the start of the AIDS pandemic, HIV/AIDS has become embedded in the culture of the planet. Yet even with AIDS in the general cultural consciousness of this nation, those that suffer from the disease are often viewed as outcasts—the unfortunate and nameless “other”. Society encourages a level of understanding of AIDS that promotes the view that AIDS is present and important but not relevant to the immediate and everyday problems of most people. Few truly understand what it is like to live with this disease. In undertaking this Independent Study, it was my goal to capture the experience of living with HIV/AIDS and show the inherent loneliness of this condition. Further, it was my hope to present the need and importance of support within the lives of such individuals. This documentary follows the life of Beverly, an HIV+ woman as she struggles to raise her HIV+ daughter, straighten her life out, find meaning in this world, and deal with the demons of her past. Paramount to this woman’s life is the positive and benevolent support of her RAIN team. RAIN, or Regional AIDS Interfaith Network, is a volunteer faith support network whose sole goal is to provide practical and spiritual support for those suffering from HIV/AIDS. Over the past four months, I have attended RAIN meetings, interviewed RAIN representatives, and visited with Beverly and her child on numerous occasions. Through my research, I discovered how pivotal RAIN’s CareTeam support is in transforming the lives of HIV+ individuals. Further, I gained an appreciation for the depth of hardship faced by those who live with this disease. More transformative, though, I learned how a difficult and trying experience can bring clarity and meaning to one’s life. In “Living with AIDS” I seek to show the power of a support system and how genuine concern and love for a complete stranger can be deeply transforming and meaningful for both the giver and the receiver.

Comparing retrograde labeling methods to visualize Xenopus retinal ganglion cell dendritic arbors in vivo.

Sarah Tyndall, Ian Willoughby, & Barbara Lom

To understand how single neurons contribute to information processing in the brain, it is necessary to investigate how dendrites develop and process the thousands of synaptic inputs they receive. In order to study dendritic growth, arborization, dendritic arbors must be clearly visualized. We employed a retrograde labeling technique to visualize Xenopus retinal ganglion cells (RGCs). By microinjecting fluorescently labeled dyes into the tectum of stage 45 tadpoles, arborizing RGC axons near the injection site took up the dye and retrogradely transported it back to their soma and dendrites in the retina. Because the only retinal projection to the tectum is via RGC axons, all fluorescently labeled neurons within the contralateral retina were necessarily RGCs. We compared how well fine dendrites were labeled by three distinct dyes (Alexa Flour 488 hydrazide, Alexa dextran 546, and rhodamine dextran). While Alexa Flour 488 hydrazide and Alexa dextran 546 labeled RGC somas, these two dyes rarely delineated dendritic arbors and frequently exhibited considerable background fluorescence. Rhodamine dextran most reliably filled RGC somas and their dendrites with less background fluorescence. Thus, rhodamine dextran is currently the retrograde fluorescent tracer of choice to label fine dendritic arbors in the developing tadpole visual system.

Analysis of purine derivatives for antimicrobial activity

Ashley Wilson, Justin Neill, Erland Stevens, and Karen Bernd

The goal of this project was to develop a novel chemical synthesis using azides and alkenes to produce purine derivatives and to test the biological activity of these compounds on a variety of microbes. Eight purine derivatives were synthesized and tested at varying concentrations (0.01M to 0.0001M) to see how they affected gram negative bacteria, gram positive bacteria, and a eukaryotic fungi (yeast). The compounds strongly inhibited yeast growth at almost all concentrations (0.001), inhibited gram-negative bacterial growth at high concentrations (0.006), and had little effect on gram-positive bacteria at all concentrations tested. Further research is necessary to explore the specific mechanism of inhibitory action.
Supported by the Merck Foundation,

Xenopus laevis lens repels retinal ganglion cell axons in vitro

William M. Wood and Barbara Lom

During development of the vertebrate visual system, retinal ganglion cell (RGC) axons exit the retina and extend to the opposite side of the brain, synapsing in the tectum. While much is known about the guidance of the axons while crossing the brain toward the tectum, little is known about the initial guidance cues of the these retinal ganglion cells as they exit the retina. Ohta et al. (1999) showed that chick RGCs are repelled by the lens, leading us to hypothesize that the Xenopus lens presents similar chemorepulsive cues that direct the RGC axons away from the lens and out of the retina, toward the brain. To test the hypothesis that the lens provides initial chemorepulsive signals to RGC axons, we cocultured Xenopus laevis eye primordia with and without lenses in collagen gel matrices and analyzed axonal growth in relationship to the lens. If the lens repels developing RGCs, then retinal neurites should avoid the lens in cocultures. Our results indicated that Xenopus retinal neurites avoid lens tissue, suggesting that the l ens may provide repulsive signals to growing RGC axons.

Retinoic acid adversely affects Xenopus laevis kidney development

William M. Wood and Barbara Lom

During normal development an embryo goes through periods of increased susceptibility to environmental factors that may cause physical deformities within the organism. These periods of susceptibility are known as either critical or sensitive periods and factors that alter embryonic development to cause deformities are known as teratogens. One such teratogen is retinoic acid (RA). If applied to Xenopus laevis before neurulation (<stage 13), RA will cause profound anterior deformities, along with kidney deformities. We examined specifically how retinoic acid adversely affected, kidney duct and tubule development. To determine what part of the kidney was affected, cryostat sections of control and RA-treated tadpoles were immunostained with both the 3G8 and 4A6 antibodies. Antibody 3G8 recognizes the tubules, while antibody 4A6 stains only the duct. Thus, these antibodies allow positive identification of the two main parts of the embryonic Xenopus kidney. By immunostaining cryostat sections of Xenopus reared in retinoic acid with the 3G8 or 4A6 antibody, we were able to conclude that while RA altered kidney morphology, both regions of the kidney are still present in RA-treated tadpoles. Our data also suggest that excess RA may enhance duct development at the expense of tubules.

Abstracts from the Department of Chemistry

Analysis of alcohol- and diol-induced a-helix formation in melittin

Lindy Baldwin, Merle Schuh, and David Blauch

It has recently been reported that alcohols, diols and fluorinated alcohols can induce proteins to take on ?-helical tertiary structures. This discovery may have implications for the treatment of amyloid diseases, including Alzheimer’s disease, in which proteins that are normally ?-helical misfold into ?-sheets. The effects of 1,4-butanediol, 1,6-hexanediol, and 2-propanol on the ?-helix content of the protein melittin were measured using circular dichroism spectroscopy (CD). The ?-helical content of melittin was measured by evaluating the CD signal of the protein-alcohol solution at 222 nm. All alcohols and diols tested were found to induce melittin’s tertiary structure to change from a random coil structure to a predominantly ?-helical structure. The transition from random coil to ?-helix was found to be a single-step process in 1,4-butanediol and 2-propanol, and 2-propanol was found to induce the transition more effectively than 1,4-butanediol. However, the data strongly suggest that melittin undergoes a two-step transition from random coil to ?-helix when exposed to increasing concentrations of 1,6-hexanediol, making 1,6-hexanediol unique among the alcohols and diols which have previously been studied.

Candidates for the homogeneous catalytic oxidation of alcohols using atmospheric oxygen

Michael Jenks, David Brown, and David Blauch

This study examines the two metal complexes to catalyze the oxidation of primary alcohols by atmospheric oxygen. The motivation for this investigation is the desirability of a green technique for selective oxidation of primary alcohol sites in carbohydrates. The two substrates chosen for this study were ?-cyclodextrin (a carbohydrate model compound) and benzyl alcohol. The two catalyst candidates are copper(II) phenanthroline [Cu(phen)2] and N,N’-bis(salicylidene)ethylenediamino-cobalt(II) [Co(salen)]. Neither complex proved effective in catalyzing the oxidation of alcohol sites in ?-cyclodextrin; however, evidence for a [Co(salen)]-catalyzed reaction between benzyl alcohol and oxygen has been obtained and the nature of that reaction is under investigation.

The formation of functional fruit: UV irradiation as a method for increasing the concentration of resveratrol in grapes and blueberries

Joshua Layfield, Felix Carroll, and David Blauch

Trans-resveratrol has been shown to prevent artery hardening as well as possessing anticancer, antioxidant, and antiplatelet, and anti-inflammatory properties. These effects have been the basis for the phenomenon known as the French or Red Wine Paradox. The presence of trans-resveratrol in grapes has led to studies of different ways to cultivate grapes so as to increase the concentration and produce a “functional” fruit. It has been reported that by irradiating whole grapes it is possible to increase the concentration of trans-resveratrol in grapes. The purpose of this study was to validate the formation of a functional fruit using grapes and to extend the technique to create functional blueberries. The experimental approach involves irradiating grapes and blueberries with UV-C light and analyzing the fruit for resveratrol content using high performance liquid chromatography.

Diffuse reflectance infrared spectroscopy as a rapid technique for the determination of organic compounds within ancient pottery

Joseph Palatinus, Ruth Beeston, and David Blauch

Potsherds from several archeological excavation sites in the eastern Mediterranean have been analyzed for organic residues using a gas chromatography-mass spectroscopy (GC/MS) technique requiring extensive sample preparation. The purpose of this investigation was to develop a method to prescreen these pottery samples for organic compounds prior to performing an exhaustive GC/MS workup. Diffuse reflectance infrared spectroscopy (DRIFT) was chosen for this purpose because it requires little sample preparation, and spectral acquisition is relatively rapid. Three fatty acid components of olive oil were prepared in a KBr matrix, and distinguishable spectra were obtained with 0.5% organic present. Heat-treated modern potsherds were spiked with trace amounts of olive oil components and principal component analysis was used to develop a mathematical method for identifying these components from their DRIFT spectra.

Abstracts from the Department of Mathematics

Seeing outside the trap

Grey Wicker

My research is on strategies of a card game called Trap, from the perspective of Game Theory. Since there are many strategies, mixed and pure, intuitive and non-intuitive, I set out to find the optimal strategy and have met surprising results along the way. Through extensive use of combinatorics and with the aid of the computer program Matlab, I have computed the number of non-card-specific dealings of 52 cards into 4 hands of 13, and the number is merely 4% of the number of dealings which seem to be possible at first glance. Through exploration of the idea of compatibility of dealings and through the development of novel card counting methods, we have discovered classifications among dealings, and are working on defining the winner in each case, based on which strategy the players use.

Abstracts from the Department of Physics

Beach ball motion damped by air resistance

Jonathan Baker

Air resistance can have a large effect on the motion of moving objects. This study explores these effects by using a beach ball-pendulum system. A PASCO interface measures angular position versus time and this data is imported into LabVIEW. In LabVIEW, the position data is fitted to the equation of motion for a pendulum: . The only parameter that is variable in this equation is c because mass, length, and gravity are all fixed by the experimental setup. From a fit of the equation’s solution to the data, c may be determined. The experiment explores the value of c as a function of the velocity and how c depends upon the shape and texture of the moving object.

Particle in potential wells

Laura Gilbert

Solutions to the Schrödinger equation describe the probability density wave function for a given eigenenergy. This investigation uses the shooting method to solve the Schrödinger equation for a particle in a potential well subject to the boundary conditions that the particle does not exist outside the box. The user selects an initial guess energy and the program searches for the next highest eigenenergy that satisfies the boundary conditions. To investigate the particle’s response to changes in the well structure, the well will be modified to include a narrow tunnel barrier or a sloped potential barrier the length of the well’s base.

Analysis of self-avoiding walks in multiple dimensions

Michael Jenks

This study explores the dimensional dependence of self-avoiding random walks (SAW). A random walk is termed “self-avoiding” when the walker can occupy no position previously occupied in that walk. Thus, in multiple dimensions, there exists the possibility for the walker to enclose himself and become trapped. As the dimensionality is increased, the probability of getting trapped should decrease since more 'escape routes' exist when a walker is closed in. This study uses multiple iterations of walks to determine the most probable number of steps before becoming trapped as a function of the dimensionality of the walk. In addition, the bias of the walker choosing one direction versus another are varied. The resulting change in number of steps taken before becoming trapped is determined as a function of both the number of steps taken as well as the change in bias.

Chaos and the double-well oscillator

Michael Kaufman

Chaos appears in many systems and evolution can be intriguing. The chaotic behavior of a particle’s motion in a periodically driven double-well potential is explored through the use of Poincaré sections and fractal basins. Poincaré sections examine the evolution of the system by monitoring it at a specific phase of the driving force. The fractal basin map displays the fate of the particle after several cycles of the system. This information is presented as color-coded map displaying the relationship between the end position and the starting coordinates. The program also explores different methods of calculation, namely the Runge-Kutta and Cash-Karp processes since chaotic behavior is highly dependent upon both initial conditions and the accuracy of the computation method.

Measured Zeeman photodetachment transition strengths

Anders Langworthy

We have probed the relative weight of the first Zeeman transition in photodetachment from O- and S- at the 2P3/2 à 3P2 detachment threshold, using laser light polarized perpendicular to a 1-T field. We find a non-zero transition strength at the first threshold, a clear discrepancy with previously published theory based on LS coupling in the ion and the atom. Our results agree, however, with other work published on detachment from Se-.

Saturated absorption and dispersion in a rubidium vapor cell

Anders Langworthy

The absorptive and dispersive properties of the atomic transitions of rubidium near 780nm are probed using a tunable diode laser and compared to both theoretical predictions and previous experimental results. The absorption and dispersion features are further examined—and Doppler broadening reduced—by using an antiparallel saturating beam to velocity-select certain atoms, a technique known as saturated absorption.

Measuring the swimming force exerted by the flagella of Chlamydomonas reinhardtii using optical tweezers

Rachel Patton McCord

Optical tweezers have many applications in measuring biological forces due to their ability to exert piconewton scale forces and to manipulate biological material with minimal damage. An optical tweezers laser trap apparatus was constructed and used to measure the swimming force exerted by the unicellular flagellated algae Chlamydomonas reinhardtii. The efficacy of this technique of force measurement was demonstrated by a comparison of the force exerted by wild type Chlamydomonas cells to that exerted by oda1 cells, a mutant strain lacking the entire dynein outer arm of the flagella. Data presented examine whether flagella regenerated by Chlamydomonas after acid-induced deflagellation are functionally identical to the original flagella. With optical tweezers, the pattern of force recovery during flagellar regeneration after deflagellation can be determined. This work both contributes to knowledge of optical tweezers and their applications and extends the understanding of Chlamydomonas as a model system and flagellar motility in general.

Reducing signal noise using the Fourier transform

Megan McDonald

When measuring a signal output from an experiment, there is often a background of noise that can complicate the analysis of the data. It is advantageous to filter the signal in order to find a smooth pattern in the noise that accurately represents the signal of interest. This program analyzes waveforms using the Fast Fourier Transform, giving the user the frequencies and amplitudes of the sine and cosine waves used to create the signal. The user can attenuate a designated frequency range, reform the signal, and synthesize a modified version of the original signal. The aim of the program is to find which frequencies can be diminished in order to minimize the effect of noise in the signal. The program uses the discrete Fourier transform, however attention to the initial parameters is important in ensuring accurate interpretation of the waveform characteristics.

Neural networks and memory

Elizabeth Miller

This study treats the brain as a network of neurons, in which each neuron interacts with every other neuron in the network. The model, which was created with LabVIEW, includes an array of Ising spins and several stored activation patterns for the system to recall. The two possible states for each spin represent the active and inactive states of a neuron. The stored patterns correspond to the energy minima for the network. The energy associated with a network configuration depends upon its similarity to these stored configurations. The neural network tends to the configuration that minimizes its total energy by changing the spins of individual neurons over time, thus “recalling” the stored patterns. The functioning of a neural network as memory, the effects of neural damage on memory, and learning are investigated.

Collective charge transport in a coulomb-blockade regime

Tuti Penev

Electron tunneling between quantum dots is important in the study of metals and semi-conductors, nanostructures, and also serves as the basis of current research in developing an up to date standard for electrical current. This simulation studies the charge transport between discrete capacitor islands connected by tunneling. We are interested in investigating the flow of electrons subject to a certain thermal energy, applied voltage across the lead plates, and nearest-neighbor electrostatic force influences. The probability of each charge making a jump to an adjacent island is determined by the electrostatic energy change of the transition, also known as the Coulomb Blockade effect, and the thermal energy of the particular charge. Using the LabVIEW programming environment, this simulation produces visualizations that demonstrate the dependence of current flow on the applied voltage and thermal energy in multi-dimensional configurations of capacitor islands.

Reflective holography and spatial filtering

Blair Reynolds

The theory underlying reflective holography is based on the fact that information recorded in the emulsion of film is generated by the intensity, not the phase, of the electromagnetic wave incident on the film. The lack of phase sensitivity in ordinary photography results in the loss of one degree of freedom in the information contained within the film and hence collapses the 3-dimensional image into a 2-dimensional image. If we could recover the lost phase information, we would regain a 3-dimensional recording of the image. Holography uses an expanded laser beam to record phase information on a medium that is usually insensitive to phase. As the beam passes through a film plate, some light remains in the plate while some light is reflected off the object back onto the plate. We can create a holographic image by exploiting the interference pattern the two beams make on the film. A technique called spatial filtering can be used to “crop off” the edges of a focused laser beam in order to produce a “cleaner” beam profile, which in turn produces clearer holographic images.

Mechanical behavior of a spinning hoop

Chris Schamper

A spinning hoop system is investigated in the context of Lagrangian mechanics. The experiment explores the non-symmetrical stable equilibria that can arise in this nominally symmetrical system. We explore the properties of the Lagrangian and the behavior of the spinning hoop when it is suspended with and without a string. Although the motion is initially symmetric about the vertical axis, the system spontaneously breaks symmetry when sufficient rotational energy is introduced about this axis.

Was Einstein wrong about quantum mechanics?

Kiril Simov

This project is based on a paper published by Einstein, Podolsky, and Rosen (EPR) in 1935. In quantum mechanics, widely separated particles can have strongly correlated behavior, a property physicists call “entanglement.” Entangled particles appear to interact with each other non-locally via an instantaneous “action-at-a-distance,” which seems to violate the theory of special relativity. The EPR paper shows how paradoxical and illogical this interaction is (for example, information must be transferred faster than light). Hence, they argued that our understanding of quantum mechanics is incomplete. However, in 1964 Bell showed that “incomplete” quantum mechanics can be distinguished from the EPR picture, and experimental results later supported non-EPR quantum theory. Our experiment involves a blue laser polarized at a 45 degree angle relative to a pair of vertically and horizontally polarized down-converting crystals. Single photons from the laser can be down-converted by either crystal into an infrared photon pair. The two emitted photons are detected through polarizers and register a count if there is a correlation between the polarization of the two photons. The statistical results are striking: two spatially-separated photons must be entangled, whereby measuring one of them produces instantaneous knowledge of the state of the other.

Temperature-dependent transient capacitance in InGaAs/InAsP diodes*

Kiril Simov and Tim Gfroerer (Davidson College)
Mark Wanlass (NREL)

For the past several years, we have been studying lattice-matched In(x)Ga(1-x)As/InAsP double-heterostructures grown on InP substrates. The epistructures under investigation range from the lattice-matched condition (x ~ 0.5) to severe mismatch (x ~ 0.8). We have found that, by including a special step-graded buffer between the substrate and the heterostructure, extremely high-quality lattice-mismatched epistructures can be grown. We would like to understand the physics underlying this important result. Photoexcitation-dependent radiative efficiency measurements suggest that the distribution of defect levels within the bandgap changes dramatically as the epilayers deviate from the lattice-matched condition. In particular, defect-levels appear to be more concentrated near the band edges with increasing lattice mismatch. We are currently using Deep Level Transient Spectroscopy to investigate this phenomenon in detail. We report the discovery of a deep defect level (activation energy = 0.30 +/- 0.02 eV) in the nominally lattice-matched material that does not appear in the more mismatched case.
* Project supported by the American Chemical Society – Petroleum Research Fund

Abstracts from the Department of Psychology

A study of physiological measures of interperonal empathy

Christina Auer and Cole Barton

Interpersonal empathy among established and unacquainted couples was studied utilizing Lanzetta and Englis’ (1989) definition, which defines empathy in terms of emotional physiology similar or identical to that of another. I examined how closely two partners’ physiological patterns covaried while one participant saw a number of emotionally-arousing slides and the other watched their partner. It was expected that partners in a romantic relationship would experience more empathy for one another than acquaintances would. It was also expected that women would be more empathic than men and that all participants would experience more empathy when their partner was presented with slides that evoked negative emotions than with slides evoking positive emotions. Trends in the data were not statistically significant, but were in the hypothesized direction.

Psychosocial aspects of the doctor-patient interaction

Benjamin Barnes, Spencer Cook, Henry Young, & Cole Barton

In recent years, the medical community has emphasized the importance of good communication skills in medical practice. Numerous studies have shown a correlation between specific physician behaviors and patients’ levels of satisfaction, compliance, and health improvements. The present study examined interactions between resident physicians and patients at NorthEast Medical Center in order to explore the relationship between antecedent and consequent behaviors and their stability over time. Participants for this study were 5 physicians in their second year of residency and 7 patients. The interactions were observed using an established coding system with an estimated inter rater reliability of 96%. Contingency table analyses of the data revealed no significant relationship between antecedent and consequent behaviors; however, descriptive statistics from the doctor-patient interaction provided useful data for the hospitals resident training program and time series analyses suggested a relationship between behaviors that varies with time.

Absentmindedness, prospective memory, and visual search: Potential links to each other and further definition of absentmindedness

Chris Davoli

This study used multiple tasks to examine event-based prospective memory, visual search, and absentmindedness in an undergraduate population. Prospective memory was measured by a naturalistic task and an experimental task, visual search was tested through two tasks in which participants located targets as quickly and accurately as possible among similar-looking distractors, and absentmindedness was assessed with questionnaires about everyday memory experiences and failures. Faster visual searchers showed a trend towards better experimental prospective memory performance, which may be explained by functional similarities in the cognitive mechanisms of these two processes, as per Moscovitch (1994). Participants higher in absentmindedness showed a trend towards worse experimental prospective memory performance, which was predicted given Schacter’s (1999) definition of absentmindedness.

Emotion ratings, confidence, & flashbulb memories in younger and older adults

Joy E. Gerdy, Kristi S. Multhaup, and Putnam C. Ivey

Brown and Kulik (1977) described flashbulb memories as “memories for the circumstances in which one first learned of a very surprising and consequential (or emotionally arousing) event” (p. 73). Cohen, Conway, and Maylor (1994) reported a lower percentage of flashbulb memories in their older adult group compared with their younger adult group. By contrast, Davidson and Glisky (2002) reported no age difference in rate of flashbulb memories. Thus whether there are age-related differences in flashbulb memory rates is an open question. The present research explored the frequency of flashbulb memories for learning the news about the September 11 attacks. We also explored possible links between the emotions experienced at encoding and later memory accuracy and confidence in memory accuracy. Older (n = 65) and younger (n = 66) adults were called within 1 week of 9-11 and again 4.5 months later. Both questionnaires asked for 6 emotion ratings (sad, angry, surprised, upset, frightened, & overall emotionality) and for 5 memory attributes (where they were, what they were doing [activity], what time it was, how they found out about the event [source], and what their first thought was when they heard the news). Accuracy scores were derived from consistency on the 5 attributes across time 1 and time 2, with perfect (10) or near perfect (9) scores constituting flashbulb memories. We found no age-related difference in rate of flashbulb memories (Gerdy, Multhaup, & Ivey, 2003). We found no evidence to support a link between emotional intensity experienced at time 1 and whether a memory at time 2 was a flashbulb memory. By contrast, we found significant positive correlations between emotion intensity ratings at time 1 and confidence in memory accuracy at time 2, supporting the idea that confidence is the key to flashbulb memories (Talarico & Rubin, 2003).

How averageness and weight of faces affect children’s and young adults’ judgments of facial attractiveness

Alissa Greenberg

These studies compared participants’ innate belief that distinctive faces are unattractive with their acquired belief that being overweight is unattractive. In Experiment 1, 37 preschoolers and 15 college students saw 30 pairs of faces and indicated which face they thought was more attractive. The pairs included an original face, the distinctive version of the original face, or the chubby version of the original face. In Experiment 2, 9 elementary school children performed the same task. The task was inappropriate for the preschoolers, although the results indicated that the elementary school children and college students both preferred the original faces over the distinctive and chubby versions. These studies demonstrate that children as young as 5 years of age have learned that being overweight is unattractive.

Cross-sensitization between opioids and cocaine: Influence of a drug’s relative efficacy and selectivity at opioid receptors

Jennifer Greene

Numerous studies have demonstrated that the repeated administration of psychomotor stimulants and mu opioids produces sensitization, a potentiated behavioral response to equivalent or lowered doses of a drug following chronic treatment. Mu opioid agonists have also been shown to produce cross-sensitization (an enhanced response of one drug following repeated administration of another drug) to the locomotor effects of cocaine. Kappa agonists, however, have been shown to attenuate the sensitization of psychomotor stimulants. The ability of opioids that have mixed action at mu and kappa receptors to cross-sensitize to cocaine, however, is less clear. The purpose of this study was to examine the role of an opioid’s relative efficacy and selectivity in producing cross-sensitization to cocaine. Rats were administered various doses of cocaine, haloperidol, morphine, BW383U86, spiradoline, buprenorphine, butorphanol, nalbuphine, or nalorphine on alternate days for 10 days. Following a 7-day abstinence period, cross-sensitization was observed in those animals treated with morphine, BW383U86, buprenorphine, butorphanol, nalbuphine, and nalorphine. Morphine, BW383U86, and buprenorphine produced cross-sensitization at only the high dose. Butorphanol produced cross-sensitization at both doses, although this effect was greater at the lower dose. Nalbuphine and nalorphine produced cross-sensitization at the low, but not the high, dose. Neither spiradoline nor haloperidol produced cross-sensitization. These data suggest that agonist activity at mu and delta receptors promotes cross-sensitization, while agonist activity at kappa receptors inhibits cross-sensitization.

Predictors of protégé success: Mentoring of college basketball coaches

McKensy Gruelle

Many organizations rely on mentoring relationships to provide new employees with skills necessary for future success. This study evaluates these relationships within the collegiate basketball domain, assessing mentor functions received by assistant basketball coaches from their head coaches. Taken into account are protégé and mentor gender, race and attitude similarity, as well as protégé and mentor ability, as measured by the coaches’ winning percentage. As a whole, similarity in gender, race and attitude was positively correlated with an increase in mentor functions, but these functions were not positively correlated with protégé success. Mentor ability was not significantly correlated with protégé success.

Emotional expression in percussion performance

Travis Lloyd

Numerous studies have demonstrated that instrumental music has the capacity to express specific emotions. While much attention has been given to the melodic, harmonic, and structural mechanisms of musical emotion, very few studies have examined the rhythmic characteristics of it. Even more exceptional is research on non-pitched idiophones. The present study used electronically created drum set patterns modeled after those used in past research to communicate specific emotions (happy, sad, angry, fearful, tender, solemn, and no expression). Listening tests revealed that the intended emotional expressions were correctly perceived. These data indicate that dynamically and temporally stable solo drum set audio recordings are sufficient to express a range of emotions. Moreover they suggest new emphasis on the role of rhythm in conveying emotion, something previously thought to be conveyed primarily by tone.

Effects of a low efficacy µ-opioid and cocaine on locomotor activity in rats

Megan Lyle

Though no effective pharmacotherapy currently exists for the treatment of cocaine abuse, low efficacy µ-opioid agonists show potential treatment value. These drugs selectively decrease cocaine self-administration without showing signs of behavioral toxicity, as they did not significantly reduce food-maintained responding (Negus & Mello, 2002). However, these µ-opioid agonists potentiate the locomotor activating effects of cocaine (Smith et al., 2003). The present study measures the interaction of cocaine and the low efficacy µ-opioid agonist (-)-cyclazocine on locomotor activity in rats. Cocaine produced dose-dependent increase in locomotor activity, and (-)-cyclazocine dose-dependently enhanced these effects. Clinicians must be aware that these opioid treatments may potentiate the effects of cocaine, perhaps in a deleterious manner.

Type versus Trait Perspectives of Personality Similarity in Relation to Roommate Satisfaction

Rebecca Lyons

Roommate satisfaction levels of Davidson College freshmen were assessed with a 15 question survey and results indicated that overall, Davidson Freshmen are satisfied with their roommates. The relationship between roommate pair personality similarity and roommate satisfaction was examined using a type-based test, the Myers-Briggs Type Indicator (MBTI), and a trait-based test, the SchoolPlace Big Five ProFile (SB5P), which is based on the NEO Personality Inventory (NEO PI-R), to determine if one of the methods of personality pairing related to greater satisfaction. Both tests failed to demonstrate a relationship between personality similarity and satisfaction. There were no significant gender differences for the relationship either. Independent of roommate match level, SB5P factor N scores predicted roommate satisfaction. These data suggest that personality similarity may not be as important to satisfaction as previously suggested and that other factors used in Davidson College’s roommate pairing process may minimize the impact of personality by compensating for personality differences with other factors such as similarity in extracurricular activities.

Socializing content of Seventeen magazine: Changes from 1986 to 2001

Anna H. Mallett

Differences in editorial content in Seventeen magazine from 1986 to 2001 were examined based on K. Peirce’s (1990) socialization study of Seventeen from 1961 to 1985. Coders labeled every page of the magazines published in 1986 and 2001 as beauty, male-female relations, home, self-development, sexuality, weight-loss, or other, and determined yearly category percentages. From 1986 to 2001, no increase in the self-development category, representing non-traditional messages of socialization, occurred. Overall, traditional socialization content levels remained the same, with the fluctuation of an increase in beauty and decrease in the home category. No other changes were significant. The concerns of a teenage girl continue to be primarily traditional: appearance and romance, and the magazine in 2001 remains very similar to 1986.

A Meta-Analysis of Motivational Interviewing

Kristen Mays

Motivational Interviewing (MI) is a patient-centered and directive counseling style for eliciting behavior change. MI has become an increasingly popular treatment modality for maladaptive behaviors including alcohol abuse, substance abuse, smoking, HIV risk, diet/health, and exercise. In an attempt to assess the efficacy of MI and to identify possible moderators of its effectiveness, a meta-analysis was conducted on 37 studies investigating the efficacy of MI across these behavioral dimensions. For both continuous and categorical data, MI yielded positive effects compared to within groups data and equivalent, but not superior, effects when compared to between groups data. The results did not support the efficacy of MI in substance abuse or exercise domains. The potential moderators of outcome type and study quality were identified using homogeneity analyses. Overall, the results of this meta-analysis indicate that for alcohol abuse, smoking problems, and HIV risk behaviors, MI interventions are better than no treatment and comparable with alternate clinical interventions. Suggestions for further research are offered.

Paired-Pulse Potentiation Lesion of the Induced Crossed Temporodentate Pathway in Rats: Electrophysiological Analysis Twelve Days After Progressive Entorhinal Lesion

McKinley Glover, Julio Ramirez and Barbara Lom

This study assessed the functional significance of lesion induced sprouting of the crossed temporodentate pathway (CTD) in rats. Unilateral entorhinal cortex (EC) lesions were performed to destroy the origin of the perforant path, which originates in the EC and provides the major input to the hippocampus. EC lesions cause profound proliferation of the normally sparse CTD. The CTD’s proliferative time course correlates directly with recovery of spatial and working memory deficits that result from unilateral EC lesion. Using the paired pulse paradigm as a simple measure of synaptic efficacy, the monosynaptic extracellular excitatory postsynaptic potential (EPSP), I evaluated the electrophysiological capabilities of the sprouted CTD at increasing interpulse intervals (IPI) from 10-500 milliseconds. Male Sprague-Dawley rats received 1) one-stage unilateral lesion, 2) progressive (serial) unilateral lesion (partial lesion followed by lesion of remaining cortex six days later), 3) priming lesion, or 4) intact control. Progressive lesions accelerate the sprouting response of the CTD and other afferents following EC lesion by four days. At 12 days post lesion, paired-pulse potentiation, an increase in the evoked conditioned pulse following a test pulse, is seen at the early phase IPIs (20-80 ms). Stable late phase depression was evident from IPIs 100 to 200 ms. In contrast to previous studies by Courchesne (2002) and Johnson (2002), there is convergence of the one-stage group with the progressive lesion group in the maximum evoked potential of the conditioned pulse. One-stage lesion animals also exhibited potentiation of conditioned pulse at IPIs 20-60 ms, which was unobserved at earlier time points. These results are consistent the hypothesis that one-stage lesion animal recovery will converge with progressive animal data at early phase IPIs (20-100 ms). These data add strength to the hypothesis that paired pulse facilitation is a mechanism involved spatial and working memory, which are characterized as short-term memory events.

Learning a map: Is movement enough?

Margaret P. Munger, Travis Lloyd, Nicole Tonelli, Jason Scott, Matt Dellinger, Katherine Johnson-Reid, Katharine Wolf, & Emily Kuhn

What kind of information about spatial layout do we generate spontaneously? We had participants view the same scene multiple times as they made judgments regarding motion of the scene. Specifically, we used a representational momentum task where short movies showing a changing view of the park was presented, and then the participants were asked if a static shot was in the same position as the final shot of the movie. When asked to do equivalent tasks with simple objects (e.g. rectangle, Freyd & Finke, 1984), participants accept positions further along the trajectory. Representational momentum (RM) distortions have been shown to occur with depth rotations (Munger, Solberg, Horrocks, & Preston, 1999), but rotations of a scene have not been examined. Our experiment asks two questions: Will we find RM for movement within a scene, and will this exposure to a scene allow participants to develop an understanding of the spatial layout?

The effect of response time on eyewitness memory accuracy and confidence in middle-aged adults

Brett Peiffer

Dunning and Perretta (2002) found that accurate undergraduate eyewitnesses made suspect identifications in 10 to 12 s. This study investigated whether their results generalized to middle-aged adult participants. Participants viewed a video clip of a suspect on the roof of a building. The viewer “walks” into her office and watches while the suspect manipulates a bombing device. Lineup identifications and questionnaires assessed accuracy and confidence. Response time was also measured. Middle-aged adults who accurately identified the suspect from the lineup were not significantly faster or more confident than participants who inaccurately identified suspects. This study did not replicate the 10 to 12 s rule discovered by Dunning and Perretta (2002), nor did it discover a rule for middle-aged adults.

Tau rAAV viral vector transduction in the entorhinal cortex causes Alzheimer’s-like behavioral deficits in acquisition of a spatial memory task in rats

Winona Poulton

Alzheimer’s disease (AD) is one of the most common types of neurodegenerative diseases, affecting close to 50% of the population over the age of 85. Clinical symptoms include but are not limited to progressive impairments in memory, language, calculation, judgment, and behavior. The entorhinal cortex (EC) plays a key role in memory function and is one of the first brain areas to reveal hallmark structures of AD. Thus the EC provides an ideal tissue to investigate incipient neurodegenerative histological signs. The protein tau may be one of the key players in AD pathology, contributing to the formation of neurofibrillary tangles (NFT) that are prevalent in diseased brains. We used gene therapy techniques to create an AD-like behavioral model by injecting an adeno-associated viral vector with the abnormal tau gene into the EC of rats. Spatial memory was then measured for approximately four months post-surgery. Rats with viral tau expression demonstrated significant spatial memory impairment relative to control rats (a vector with a GFP marker). Our results suggest that abnormal tau expression may severely impair the acquisition of spatial memory tasks relying on working memory. Supported by NIH (grant number MH60608).

Bilingual Source Monitoring: Language as a Source Characteristic

Susan G. Robison

The present study investigated language as a source characteristic for source monitoring in balanced and unbalanced French-English bilingual participants. In the control condition, participants watched 4 scenes of a movie in English. In the experimental condition, participants watched 4 scenes of a different movie that alternated between French and English presentation. After a 30 min delay, participants completed a source-monitoring task identifying the origin of idea units as person A, person B, person C, or new, and perceptual memory questions. A significant interaction between bilingual group, condition, and question type (source, perception) was found, with unbalanced participants’ source memory adversely affected as a result of alternating language. The results have implications for bilingual information processing.

Evaluation of a wireless laptop technology implementation in a secondary school

Ryan Scott

The purpose of this study was to evaluate the impact of a pilot wireless laptop program on student attitudes toward computers and school. A quasi-experimental design was used with pre- and post-scores being obtained for the 9th grade laptop group and a control group of 10th and 11th grade students. Students were surveyed using the Computer Attitude Questionnaire and a two-way mixed factorial ANOVA was conducted to determine the effects of being given a laptop over time. Data was analyzed across the entire sample of students as well as specific sub-samples of students who varied in terms of their experience and proficiency with computers. None of the hypothesized laptop by time interactions were found. Low experience and low proficiency students reported higher means for most computer-related attitudes and improved computer confidence scores. High proficiency students reported increased anxiety and decreased confidence. Teacher attitudes were collected using the Teachers’ Attitude toward Computers Questionnaire. Correlational analysis replicated the existing relationships among teachers’ attitudes toward computers, especially the importance of experience. Based on these results, implementers should recognize the differential impact of an educational technology program on students with less computer experience and proficiency and the importance of experience for teachers’ attitudes.

Implications of Motivational Differences Between Subgroups and its Effect on Organizational Citizenship Behavior

Kea Sherwood

This study examined whether employee’s extrinsic or intrinsic motivation differed depending on their race and how these differences in motivation affect extra-role behaviors, such as Organizational Citizenship Behavior (OCB). The participants’ motivational preferences for extrinsic or intrinsic motivators were determined by using a survey adapted from the Job Diagnostic Survey. Participants were also evaluated by their co-workers regarding the extent to which they engaged in organizational citizenship behaviors. No significant differences were found between the different ethnic groups for either extrinsic or intrinsic motivation and OCB.

Effects of flunitrazepam and pentobarbital on motor performance

Joseph J. Taylor

The presence of drugs in sexual assault cases, particularly benzodiazepines and barbiturates, has caused researchers to investigate the motor impairing effects of these drugs alone and in combination with one another. The effects of flunitrazepam, a popular benzodiazepine, and pentobarbital, a popular barbiturate, were evaluated using a rat model of motor performance. Each rat was tested for latency to fall from a rotorod rotating at 16.0 rpm after administration of increasing doses of flunitrazepam and increasing doses of pentobarbital pretreatment. Flunitrazepam dose-dependently impaired motor performance when administered alone, and pentobarbital non-significantly enhanced these effects in drug combination tests. These data suggest that flunitrazepam and pentobarbital may produce dangerous interactions on motoric behaviors when co-administered.

Risk-taking behavior in children: A gender and socioeconomic study

Sarah Vaala

This study examined whether parental reported physical risk-taking behavior in school-age children correlated with parents’ education level and children’s gender. Parents reporting either more than 16 years (n = 33 ), 13 to 16 years (n = 26), or 12 or fewer years of education (n = 17) filled out surveys indicating the number of times they have known their child to engage in 20 physically risky behaviors (e.g., “run down a very steep hill”). I hypothesized that boys would have higher reported rates of risk-taking behavior, and that boys of less educated parents would be especially high, creating an interaction between parents’ education level and children’s gender. The results did not confirm a correlation between children’s over-all risk-taking and gender or parents’ education level.

Representational Momentum in Scenes

Katharine Wolf, Katherine Johnson-Reid and Matthew Dellinger

Representational Momentum (RM) is memory distortion that occurs when people perceive an object to be further along its anticipated path of motion than has been presented. In previous studies RM has been tested using a two-dimensional stimuli such as a rectangle (Freyd & Fink, 1984), and also using three-dimensional stimuli, such as a cube (Munger, Solberg, Horrocks & Preston, 1999). Recent research has shown that RM is also present in scenes (Thornton & Hayes, 2004). In the present study, using a realistic park stimuli, we confirm that RM can be found for objects moving in a scene. In a second experiment we examined RM at the edge of scenes for objects coming into and going out of view. Significant RM was observed for both directions with larger RM distortions when objects were moving into view.


The Office of the Vice President for Academic Affairs generously provided funds for the 2004 Science and Math Student Research Symposium. Special thanks go to Drs. David Brown and Tim Gfroerer for their helpful recommendations, and to Ms. Fern Duncan for her invaluable assistance during the coordination of this year’s event.

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