STUDENT ABSTRACTS

ASTROPHYSICS

h and Persei: An Analysis of Cluster Membership
Rebecca T. Cover
I conducted CCD photometry of h and Persei, the well-known pair of galactic clusters, and derived a catalog of probable cluster members. I received the data from Scott Wolk of the Harvard-Smithsonian Center for Astrophysics, who took images of h and Per at the Fred Lawrence Whipple Observatory in Amado, AZ, in December 1998. I reduced the data with IRAF (Image Reduction and Analysis Facility) between June and August 1999, obtaining U, B, V, R, and I magnitudes (ultraviolet, blue, visual, red and infrared) with less than 5% uncertainty. I then used IDL (Interactive Data Language) to construct color-magnitude diagrams, contour plots, and graphs of density as a function of distance from the cluster centers. Based on the color-magnitude diagrams and the results of earlier studies, I found h Persei to be more distant than Persei. By analyzing the stars’ positions on the three types of diagrams, I selected candidates for membership and identified their membership probability.

Chapter 1 summarizes previous studies of h and Per, while Chapter 2 relates their properties and those of open clusters in general. Chapter 3 explains the data reduction procedure, and Chapter 4 describes the data analysis. Chapter 5 assesses potential sources of error. Chapter 6 introduces the catalog, which lists 11,000 stars.

Observations of Coronal Temperature and Polarization from the 11 August 1999 Total Solar Eclipse
Sara Kate May
We present observations of the 11 August 1999 total solar eclipse from Rimnicu Vilcea, Romania. Addressing the problem of coronal heating and using a theory first proposed by Lawrence Cram (1976), we seek to measure the degree of Doppler broadening in the K-coronal spectrum and thus infer the electron temperature. Three sequences of data were successfully acquired during totality through all combinations of three filters and four polarizers (including an unpolarized glass position) and reduced using standard techniques. As an intermediate step to the temperature calculation, polarization measurements were made to separate the K and F coronas. Our polarization data confirm the observations of several other groups at this and earlier eclipses and agree with calculated values of polarization suggested by some models. Though our temperature measurements are not absolutely calibrated, a relative temperature map was produced. Possibilities for future improvements and observations are presented.

A Search for High-Frequency Coronal Oscillations at the 1999 Total Solar Eclipse
Kevin D. Russell
We acquired CCD images of the solar corona at 10 Hz at the total solar eclipse of August 11, 1999, from Rimnicu Vilcea, Romania, to try to detect high-frequency waves along coronal loops. The presence of magnetohydrodynamic waves in our frequency domain is predicted by some theories to explain the energy transfer that heats the corona to millions of kelvins. Only minor adjustments to the procedure and apparatus of the 1998 experiment, described by McConnochie ’98, were made. Fourier analysis of actual data and Monte Carlo simulations using a computer model of the 1999 eclipse indicate that we have the ability to detect oscillations with amplitudes near 0.4% of total coronal intensity with widths near 0.2 Hz in frequency space. For the 1999 eclipse data, I carried out Fourier analysis of every pixel, and also of every pixel binned 2x2 in both frequency and physical space. The results of this comprehensive analysis were used to map where in our image the highest peaks occurred. A strong correlation between high peaks and coronal loop structure suggests that real oscillations in the 1 Hz range are the source of increased power, though we cannot yet rule out power introduced by image motion from frame to frame. Various methods for resolving this question are presented, and a possible method with the required precision to reach a conclusive answer is outlined.

BIOLOGY

Characterization of the Role and Regulation of the Hunchback Gap Gene Orthologue Lzf2 in Leech Development
Stephanie J. Airoldi
This study aims to elucidate the role and regulation of Leech Zinc Finger II (Lzf2) in Helobdella triserialis and to isolate can characterize a leech homologue to the Drosophila gene caudal. Lzf2 is homologous to the Drosophila hunchback gene, which is critical for the proper anterioposterior development of the fly embryo. Functional studies using double stranded RNA interference (RNAi) indicate that Lzf2 plays a role in directing the morphogenetic movements of leech gastrulation. Regulation of Lzf2 was not successfully characterized, but the presence of a Nanos Response Element (NRE) like element in the 3’UTR of Lzf2 (Savage and Shankland, 1996), as well as the presence of a nanos homologue (HRO-NOS, Pilon and Weisblat, 1997) indicate that while the function of Lzf2 may be different from that of hunchback, the two homologues may be regulation similarly. Elucidation of the function and regulation of Lzf2, as well as characterization of other segmentation genes in the leech, will reveal information about leech development as well as the evolutionary conservation of homeotic genes.

The Dynamics of Temperate Forest Fragmentation: An Examination of Susceptibility to Woody Invasive Species
Lauren B. Buckley
Forest fragmentation and the invasion of non-native species are two current threats to global biodiversity. We investigate whether fragmentation increases the susceptibility to woody invasive species in ten remnants (2 to 126 ha) of Eastern deciduous forest. We counted all woody individuals in plots located in belt transects at the edge and center of each fragment and midway between. While 40% of edge individuals are invasive, interior regions have fewer invasives (14%). Species richness, abundance of individuals, and the percentage of invasive species decline significantly from both the edges to the centers of the fragments and with increasing fragment area. These patterns result from increased susceptibility to invasive species in edge regions and in smaller fragments. The increase in non-native species with decreasing fragment area does not correspond to an equivalent decline in the native species community, suggesting that non-native species may colonize an empty habitat niche associated with the fragment edge. However, the interiors of larger fragments had a richer community of native species. Overall community diversity and evenness indices do not vary with fragment size, which suggests their ineffectiveness in assessing the integrity of fragmented forests. The diversity and evenness indices do, however, reflect the expansion of the non-native species community with decreasing fragment area. Our results provide support for conservation efforts dedicated to preserving large tracts of eastern deciduous forests in order to minimize the invasion and dominance by non-native woody plants.

Characterization of the Plastic Response of Pseudacris triseriata and Identification of a Method to Elucidate the Molecular Components
Patrick M. Burton
Pseudacris triseriata tadpoles were exposed to a natural predator, the Aeschna juncea dragonfly nymph. Tadpoles underwent the characteristic plastic response. Compared to controls, exposed tadpoles had larger tail fins, deeper tail muscles, and tail-fin attachment points were closer to the head. These changes were all significant (p<.05).

I compared expression patterns of these tadpoles with controls using two different methods. Specific northern hybridization of Xenopus laevis growth factors was used for direct hypothesis testing, but failed to show significant changes in gene expression. Restriction fragment differential display allowed hypothesis building. Results from this method were readily obtained and yielded reproducible products. Comparison between tadpoles resulted in isolation of nine products, six of which were sequenced. The final three products are currently being investigated.

Use of Zebra Finches for Refining DNA and Song Comparison Methodology, In Order to Delve Into Transmission of House Finch Song
Sadruddin K. Chandani
Transmission of birdsong in house finches (Carpodacus mexicanus) is highly complex, not simply because song is learned, but also because, in the particular case of house finches, song learning occurs every season. New ways in which to explore song transmission must be found, and the existing methodology of analysis must be improved. Zebra finches (Taenopygia guttata) and their song learning system can be used as a simplified model of house finch song transmission; zebra finches are “simpler” because they are “critical-period” learners, who form a set song and stop learning relatively early in life, and also have a less varied, less rich song. This study suggests that zebra finches are also problematic as a tool of refinement for DNA analysis, since extraction conditions seem to differ substantially between the two species. However, using zebra finch song for quantitative comparison purposes demonstrates that song comparison is a viable way to explore transmission, especially by correlating trees that show relatedness between individuals, and are derived from a variety of morphological characteristics including song. Due to the complexity of house finch song, a system for comparing house finch repertoires must be developed that is comprehensive enough to accurately and reliably score repertoire similarity. The revision of the classification system of house finch songs in this study was a preliminary step towards developing such a system. The ability to quantitatively compare house finch song will greatly facilitate the investigation into how song is transmitted and learned in this species. Revealing how the complex system of song transmission in these birds operated will not only be of importance for understanding general patterns of learning in organisms, there may also be findings that can be applied for speech and language development in human society.

Regulation of Vaccinia Virus dUTPase Expression and Activity in vivo
Erin L. Davies
Vaccinia virus dUTPase, an enzyme encoded by the nonessential, early phase gene ORF F2L, is a critical component of the de novo pyridine biosynthetic pathway whose function is also important to the maintenance of DNA replication fidelity. DUTPase hydrolyzes dUTP to dUMP and pyrophosphate, a reaction which simultaneously furnishes thymidylate synthetase with its substrate, dUMP, and reduces the intracellular dUTP.dTTP ratio, thereby preventing the misincorporation of dUTP into nascent DNA molecules. Mutagenic U-DNA activates an interactive excision-repair process catalyzed by uracil DNA-glycosylase, which ultimately leads to chromosome fragmentation and cell death. An understanding of how vaccinia virus dUTPase production and activity are regulated in vivo will provide insight into the processes of DNA replication and viral pathogenesis, and will aid in anti-viral drug design. Therefore, profiles of vaccinia virus dUTPase expression, stability, activity, and phosphorylation spanning the eight-hour viral replication cycle in BSC40 cells were generated. Although dUTPase is translated between two and five hours post-infection (hpi), the enzyme is long-lived and does not undergo appreciable turnover through 10 HPI. Once translated, the enzyme is phosphorylated immediately, and shows basal levels of activity. A dramatic increase in dUTPase phosphorylation levels is seen between five and six hpi, which coincides with the steady rise in catalytic activity seen late in infection must be the result of a positive post-translational regulatory mechanism. It was proposed that phosphorylation events allosterically active dUTPase, due to the strong correlation between dUTPase activity and phosphorylation levels throughout infection. In order to identify the phosphorylated residues, phosphoamino acid analysis was performed on immunopurified dUTPase using a 2D-TLC system. Preliminary experiments suggest that vaccinia virus dUTPase is phosphorylated on tyrosine and threonine residues in vivo.

Tidal Pulsing, Environmental Variability, and Phytoplankton Dynamics in the Mystic River Estuary
Joshua H. Goldstein
An ecosystems-level study of the Mystic River estuary, CT, USA was performed to examine how short-term environmental variability, induced by pulses such as tidal cycles and storm events, influenced short-term variability in phytoplankton dynamics. Salinity, temperature, dissolved oxygen, turbidity, nutrients, fluorescence, chlorophyll a, and phytoplankton counts were measured at a series of stations along the estuarine gradient from mid-June through mid-August 1999. Vertical and horizontal stratification throughout the study period was minimal due to the severe drought conditions. Fluorescence levels throughout the estuary pulsed on an approximately two-week cycle, with peak magnitudes increasing as the summer progressed, and this fluorescence pulsing appeared to be connected with the neap-spring tidal cycle. Tides deliver energy to an estuary, and the second-order fit between tides and fluorescence suggested that photyplankton biomass was maximized at intermediate levels of tidal energy. Nutrient availability was a major factor driving variability in phytoplankton biomass, and this suggested that the coupling between tidal energy and phytoplankton dynamics was driven by resuspension of benthic nutrients by tidal mixing. The high levels of phytoplankton biomass observed in mid-August appeared to be caused by the synchronization of a tidal pulse with a storm pulse. The strength of pulses dampened going down the estuarine gradient, and the highest phytoplankton biomass was found in the upper part of the river where environmental variability was greatest. Tidal fluctuations induce periodic short-term variability in physical and chemical conditions, and tidal pulsing appears to be an important, regular, external pulse driving short-term variability in phytoplankton dynamics in the Mystic River estuary.

Injection of the Mauthner Cell with Postulated LTP-Induction Enzyme, CaMKII, May Potentiate the C-Start Reflex in Goldfish
Jason M. Langheier
Long-term potentiation (LTP), the NMDA receptor (NMDAr) and Ca2+ dependent increase in synaptic efficiency found neural pathways, has long been postulated as a mechanism for memory and learning. This hypothesis has never directly been proven in a vertebrate model.

CaMKII is involved at least in the induction phase of rodent hippocampal LTP (Lledo, et al., 1995), and is also active in response to the LTP-producing NMDAr-dependent Ca2+ influx observed upon the delivery of a tetanus to the goldfish posterior VIII nerve, which synapses on the Mauthner cell (M-cell) lateral dendrite (Yang, et al., 1990). Direct injection of the activated enzyme into the lateral dendrite has been shown to potentiate both electrical and chemical synaptic conduction (Pereda, et al, 1998). Gathering excitatory auditory and displacement input from nerve VIII, the pair of M-cells of the medulla are also known to initiate the C-start startle reflex, which can be measured by high-speed cinematography.

Pressure injection of CaMKII into the left M-cell of one animal caused it to only have C-starts to the right of the controlled by that cell, at 1 and 2 hours post-injection, as elicited by a suprathreshold vibratory stimulus. The fish also showed spontaneous rightward jerks and a lowered threshold for sound evoked rightward C-starts in that time period. Interestingly, at 4 hours and thereafter, the fish only gave C-starts to the left.

That potentiation could give one cell a competitive advantage during suprathreshold stimulation of both cells might be explained by the theory that LTP at the excitatory synapses of the M-cell lead to faster excitatory postsynaptic potentials (reflected in larger slope), such that the cell which fires first inhibits the other cell and initiates the C-start on the contralateral side of the body. Among the possible explanations for the loss of the rightward C-start are that the cell died due to injection of CaM excitotoxicity, or that a late-phase potentiation of inhibitory synapses occurred. If the last possibility is shown to be true, one must question whether LTP may not be a memory mechanism, but a means of cellular arousal which homeostatic mechanisms correct for in eventually bringing synaptic efficiency back to baseline.

What Regulates the Regulator? A Study of the in vivo Transcriptional Regulation of the Muscle-Specific Transcription Factor MyoD
Randall L. Lindquist
Muscle fibers are generally specialized for power or endurance; these specialized fibers are called fast and slow muscle, respectively. The principal determinant of muscle fiber type is the Myosin Heavy chain (MyHC) protein, which drives sarcomeric contraction. Muscle fiber type is highly oastic; muscles can switch their fiber type in response to mechanical, neural, or hormonal stimuli. Such a change in muscle fiber type ultimately results in corresponding changes in the cellular expression of MyHC isoforms and in the velocity of muscle contraction. Previous work has suggested that the muscle-specific transcription factor MyoD regulates muscle fiber type and is involved in slow-fast fiber-type transitions; MyoD had previously been shown to be pre-translationally upregulated in fast muscle. Somatic cell gene transfer was used to examine the in vivo transcriptional regulation of MyoD in the tibialis anterior (TA) and the soleus, representative fast and slow muscles of the rat hindlimb; it was shown that the 258-nucleotide MyoD distal enhancer is sufficient to confer fiber-type specificity on a SV40 promoter-luciferase construct and that a 25 base-pair region of this MyoD enhancer is required for transcription in both the Ta and the soleus. There is a consensus AP-1 site in this 25 base-pair region; it is proposed that fos and jun bind to this AP-1 site in conjunction with one or more trans-acting factors whose expression is fiber-type specific to stimulate transcription at a higher level in the TA than in the soleus.

Retinal Ganglion Cells Regenerate to a Muscle Target
Melissa Motta
The Optic Nerve (ON) is comprised of Retinal Ganglion Cells (TGCs), which have their soma in the retina and project to the optic tectum in the brain. Unlike central neurons in mammals and birds, neurons in the central nervous system (CNS) of fish – such as RGCs – are capable of regenerating and restoring vision. Though RGC show highly specific regeneration to the optic tectum, it has been shown that they are capable of regenerating to non-standard targets in the brain. Moreover, RGC can be redirected through peripheral nerve implant to non-optic brain regions. In the present study, the ON in Goldfish was transected and a section of peripheral Lateral Line (pLL) nerve was used to redirect the RGC to a peripheral muscle target. The RGCs regenerated through the pLL nerve bridge and projected over the superior oblique, an extraoccular muscle. After 60-90 days the neurons were stained with Neurobiotin and could be raced leaving the ON, through the implant and onto the superior oblique muscle. Some axons appeared to separate from the nerve bundle projecting on the muscle and synapse on single muscle fibers. This study validates the capacity of CNS neurons, which are glutameric, to project to and synapse on a peripheral muscle target, which is cholinergic.

Higher Cortical Reorganization in Response to Peripheral Nerve Regeneration in the Zebra Finch
Charles N. Munyon
The zebra finch (Taeniopygia guttata) is a songbird with a closed-ended learning period that ends at sexual maturity, around ninety days of age. Transection of the right tracheosyringeal nerve (NXIIts) in the adult male zebra finch results in immediate perturbation of the frequency modulations which compose that male’s song, but does not disrupt its temporal structure (McKibben, 1989). Upon regeneration of the transected nerve, some of the original song’s fidelity is restored in a manner that is dependent on the lateral magnocellar anterior nucleus of the neostriatum (LMAN) (Mehta, 1994). This recovery accompanies a randomization of the topographic map of the tracheosyringeal motor nucleus (nXIIts), which is responsible for controlling the muscles of the syrinx, the bird’s vocal organ (Linck, 1999). The goal of this study was to examine the effects of nerve transection on the neuronal map of nucleus Robustus Arthistriatalis (RA), which innervates nXIIts, in the hope of better understanding the mechanisms by which some degree of plasticity is retained in crystallized song. Injections of retrograde tracer into the syrinx and of anterograde tracer into nucleus RA were administered in an attempt to visualize any perturbations in the maps of both nXIIts and RA. Complications with the experimental protocol prevented observation of the map of Ra in a transected male, but this report offers suggestions for continuation of the study which should alleviate these difficulties.

Cytochrome C and Lipid Interactions in the Mitochondrial Membrane
Jillian A. Pesin
Sphingolipids act as bioactive molecules involved in signal transduction and cell regulation. Previous studies have shown that, in animal cells, ceramide induces cytochrome c release and the formation of reactive oxygen species in the mitochondrial membrane, both hallmarks of apoptosis. No studies have been done to investigate the possible role of ceramide in apoptosis in plant cells. Phaseolus vulgaris mitochondria were used to measure cytochrome c release from the mitochondrial membrane and the formation of reactive oxygen species. The cytochrome c release assays were inconclusive while the reactive oxygen species were induced by incubations with sphingolipids. The physical interactions between sphingolipids and cytochrome c were investigated using isothermal microcalorimetry. Heat change was measured during interactions between sphingolipids and cytochrome c, sphingolipids and liposomes, and sphingolipids and liposomes containing cytochrome c. Ceramide showed the strongest association with liposomes containing cytochrome c, suggesting that it interacts directly with cytochrome c while the protein is poised in the mitochondrial membrane.

Investigation into the Function of the Hunchback Orthologue, LZF2, in Leech Development
Kerice A. Pinkney
A further investigation into the genes controlling segment pattern formation in leeches has been the main focus of this lab’s studies. Critical attention has been paid to the Leech Zinc Finger II gene (LZF2), in an attempt to characterize the role it may play in leech development. LZF2 is the leech orthologue of the Drosophila hunchback (hb) gene. It appears as if translational repression, possibly mediated by a nanos response element-like motif in the gene’s 3’UTR, may be guiding protein expression. This hypothesis is given credence by the recent finding of the nanos homologue, Hro-nos, in leeches. Based on this theory, experiments designed to manipulate the 3’UTR segment of the LZF2 gene were performed. While the results of these experiments have not been conclusive, they do provide us with some insight into the validity of this theory. Interestingly, dsRNA experiments with LZF2 have indicated that LZF2 plays a role in proper embryogenesis in the leech.

The Evolution of Plasticity and Local Adaptation: Confronting a Computer Simulation with Empirical Data
Ethan Plunkett
Almost all species encounter habitat heterogeneity. Determining how species react to that heterogeneity is an important evolutionary question. I used known life history factors of an intensely studies natural population to simulate on a computer the evolution of plasticity and local adaptations in response to a heterogeneous habitat and predict the population structure and genetic state of a natural population.

The simulation predicts that migration between habitat types is necessary to maintain plasticity; that in simple environments selection favors local adaptation over plasticity; that fragmenting a population will increase drift and that this drift will, in turn, drive migration between fragments; and that increasing habitat uncertainty in the form of periodic storms will maintain migration, maintain plasticity, and eliminate local adaptation.

The Empirical findings, that there is plasticity in the natural population and that there is no local adaptation, support the predictions of the model; together they suggest that habitat uncertainty maintains phenotypic plasticity and prevents local adaptation in the North Government Island chorus frog population.

An Analysis of CDC14 and SFP1 Interactions Using Temperature-Sensitive Mutants and the Yeast 2-Hybrid System
Kate D. Ramsayer
In order for a yeast cell to exit from mitosis, the Cdc28/Clb2 complex that provides the main catalytic mechanisms for mitosis must be degraded. This is achieved through three different pathways in Saccharomyces cerevisiae that involve Swi5, Sic1, and Hct1/Cdh1, each of which is regulated by the dual-specificity phosphatase Cdc14. Cdc14 dephosphorylates and activates these proteins, allowing Sic1 to inhibit Cdc28/Clb2, Swi5 to up-regulate the transcription of Sic1, and Hct1/Cdh1 to induce the APC to degrade Clb2. Cdc14 itself is regulated by Net1, which tethers Cdc14 in the nucleolus for the majority of the cell cycle until it is released through the activity of TEM1.

In doing a search for suppressors of temperature-sensitive cdc14 mutants arrested in late telophase, it was discovered that there is an interaction between CDC14 and SFP1, a zinc split finger protein (Sagasti, 1996; Paliulis, 1997). By sequencing the cdc14-8 allele, which is the sole cdc14ts mutation not suppressed by sfp1, the cdc14-8 mutation was found to be a change from proline to serine at the 53rd amino acid residue of the CDC14 gene. This is a significant change in amino acid structure and probably significantly alters the conformation of the cdc14-8 protein.

To determine if there is a direct, protein-protein interaction between SFP1 and Cdc14, a plasmid with the SFP1 gene inserted into a 2-hybrid expression vector was constructed using PCR mutagenesis, restriction enzyme digestions, and ligation reactions. PWR1084, the pGAD/SFP1 vector, was then transformed with pGBDu/CDC14 into the yeast host strain PJ69-4A in a 2-hybrid test. While initial results were positive, implying that there is a protein-protein association of Cdc14 and Sfp1, additional controls gave questionable results; thus additional experiments need to be run to confirm this interaction.

Influences on Distribution of Spring Ephemerals on the Mount Greylock Reservation, Williamstown, MA
Aya E. Reiss
Spring ephemeral distribution in Williamstown has been significantly linked to influences of past land use (Nash 1994; Grossmann, 1996; Halbach, 1997). Alterations to the landscape of the Mount Greylock Reservation have been varied throughout the history of Williamstown. Disturbances through agriculture, logging and landslides have changed the forests, and most especially the herbaceous layer. Forests which have been cleared are termed secondary woods, whereas those which remain in the old growth state or were used with minimal disturbance, such as woodlots, are termed primary woods. The herbaceous layer recolonization patterns of secondary forests are strongly influenced by seed dispersal mechanisms. Ant dispersed species are much slower to return to a secondary woods than wind or vertebrate dispersed species (Nash, 1994). While land use does remove an existing seed source and therefore deplete a forest of its herbaceous species, the Mount Greylock Reservation has more significant limitations to growth. Distribution patterns of spring ephemerals on the Mount Greylock Reservation are largely controlled by elevational influences. Changes with increasing elevation include increasing acidity, decreasing nutrient availability and changes associated with shifts from deciduous to coniferous forests. In addition to the impacts of past land use, climate and forest extremes dictate the areas for potential growth on the Reservation, limiting many herbaceous species to the lower elevational ranges. Therefore, in areas above 1500 feet, the physical environment overwhelmingly influences spring ephemeral distribution, unlike other parts of Williamstown where land use appears to be the primary factor controlling wildflower abundance and dispersal.

Exploring Regulation of CDC14 in Exit from Mitosis: Characterization of a cdc14 Mutation and a Search for the Mechanism of Inhibition by SFP1
Daniel J. Richter
In eukaryotic organisms, major cell cycle events are induced by the activity of cyclin dependent kinases (Cdks). Exit from mitosis is one of the two key cell cycle transitions that govern the switch between high and low states of Cdk activity. CDC14, a protein phosphatase, is the farthest downstream of any single gene required for mitotic exit in budding yeast, Saccharomyces cerevisiae. A series of genes including TEM1, LTE1, CDC15, DBF2/DBF20, CDC5, MOB1 and NET1 are involved in the regulation of CDC14, a significant component of which is nucleolar sequestratin via Net1 and the RENT complex. Two cdc14 temperature-sensitive mutant alleles were previously identified: c14-2 and cdc14-8. SFP1 is a split zinc finger protein whose mutation or deletion is capable of partially suppressing the cdc14-2 mutant allele, but is incapable of suppressing cdc14-8. Sequence data show that cdc14-2 has a point mutation near the active site, and that cdc14-8 has a point mutation in an unrelated part of the protein. I examined the consequences of these mutations in light of the differential suppression by sfp1 mutants and will suggest possible modes of action for SFP1. Furthermore, I will propose and partially implement two novel ways to investigate the relationship between CDC14 and SFP1; polymerase chain reaction epitope tagging (PET) of SFP1 to detect protein-protein interaction and electrophoretic mobility shift assays (EMSAs) of SFP1 with possible CDC14 promoter sequences to test for transcriptional regulation.

A Kinetic Examination of the Vaccinia Virus Deoxyuridine Triphosphatase (dUTPase)
Jeffrey D. Roizen
Deoxyuridine triphosphate pyrophosphatase (dUTPase, EC 3.6.1.23) is a ubiquitous enzyme which catalyzes the cleavage of deoxyuridine triphosphate (dUTP) to deoxyuridine monophosphate (dUMP) and pyrophosphate (PPI). The dUMP product of this reaction is an intermediate in the pathway towards synthesis of deoxythymidine triphosphate (dTTP). As this enzyme is necessary for DNA replication, it is a tempting target for cancer treatment and antiviral chemotherapy. In addition to the practical interest in this enzyme, it has several unique enzymatic characteristics, including active sites formed by portions of all three subunits of the active trimer, which make it an intriguing focus for research. Preliminary data from crosslinking experiments suggests that this enzyme may exhibit some kind of cooperativity.

To examine the cooperativity of this enzyme, kinetic studies were undertaken over a large range of substrate concentrations (0.05 μM to 200 μM) to generate a Hill Curve. In order to perform these studies, dUTPase was overexpressed in a T7 RNA polymerase overexpression system, and then subsequently purified using affinity chromatography and then ion exchange chromatography. From these kinetic studies, it was learned that the vaccinia virus dUTPase is negatively cooperative, with a Hill coefficient (nH) equal to 0.63155 (in units of log μM). It was found that the dUTPase has three distinct apparent KmS (in increasing order: –0.07 μM, -0/47 μM and ~3.6 μM) and that the overall Vmax for the enzyme is ~8.7*10-9 μmoles/sec [with the VmaxS equal to (in increasing order) ~2.5*10-9 μmoles/sec and ~6.2*10-9 μmoles/sec.] We are thus the first lab studying dUTPase to report such a result, which only adds to the rich uniqueness and intellectual intrigue of this enzyme. This negative cooperativity may be due to enzymatic or systemic evolutionary pressures.

The Role of MyoD in Muscle Fiber-Type Maintenance: A Tissue Specific Phenomenon
David J. Seward
In this study, we endeavored to characterize the role of MyoD, a myogenic transcription factor, in muscle fiber-type maintenance. Previously it has been proposed that MyoD plays a causal role in the transcriptional activation of the type Iib myosin heavy chain (MHC) gene. Using MyoD -/- mice in concert with hindlimb unweighting we obtained data linking MyoD to Iib MHC gene induction in the soleus and diaphragm muscle of wild-type (WT) mice. MyoD -/- mice do not express MHC protein in their diaphragm. In response to unweighting, the MyoD -/- soleus does activate expression of the MHC Iib gene, but to a lesser degree compared with the WT unweighted soleus. Significant variations in the MHC protein composition between the diaphragm, biceps, and masseter of WT and MyoD -/- mice support the view that in certain muscles MyoD is in fact required to maintain a WT-like MHC protein profile. Together these data suggest MyoD is a tissue specific enhancer molecule able to mediate Iib expression when the necessary basal transcriptional machinery is in place. However, it is clear that MyoD should no longer be thought of as playing a causal role in Iib MHC expression as MyoD -/- mice are able to express Iib MHC protein in several muscle tissues. It would appear that MyoD’s role can be altered in a given muscle tissue depending upon external stimuli and the presence of tissue depending upon external stimuli and the presence of tissue specific cofactors.

Factors Affecting the Distribution of Spring Ephemerals on the Taconic Range
Emily L. Simpson
During the initial settlement of Williamstown, much of the Taconic Range on the western boundary of town was divided into lots and cleared for farms, removing the native flora of the temperate deciduous forests. While farming was extensive, reaching slopes higher than 1500 ft in elevation, it only lasted generally less than a century and by the mid-1800s most of the farmland on the Taconics had been abandoned leaving the land to recover its native forests. Forests that returned to these agricultural areas are considered secondary, while forests that were not cleared are considered primary and represent the undisturbed flora. The herbaceous communities of these secondary and primary forests are considerably different due to their divergent land-use history. Primary forest tend to have a richer and more diverse herbaceous population, while secondary forests are less rich and diverse, due mostly to the absence of myrmemecochorous (ant-dispersed) species which are slow to re-colonize past agricultural areas. Past land-use is only one of many factors affecting herbaceous distribution above 1500 ft however. Elevation also tends to limit species. Lower elevation sites have richer more diverse populations while areas above 2300 ft contain species not found at lower elevations. Another important factor is the aspect or topographic position of an area, with dry south-facing slopes and ridge-tops having lower richness and diversity than moister valley bottom and north-facing slopes. The difference in herbaceous distribution within these three factors of past land-use, elevation, and aspect are linked to characteristic soil nutrients and canopy compositions.

Development of an In Vitro Vaccinia dUTPase Phosphorylation System
Lauren M. Singer
Vaccinia Poxviridae is a double stranded DNA virus that infects a wide range of mammalian hosts. The virus replicates in the cytoplasm of the host cell. Independence from the host cell nucleus requires vaccinia to encode its own DNA replication machinery. One enzyme important in maintaining vaccinia’s nucleotide pol is deoxyuridine 5'-triphosphate nucleotidohydrolase (dUTPase). DUTPase hydrolyses dUTP to dUMP, which increases levels of dUMP, a precursor in thymidine synthesis, and decreases levels of dUTP, thereby reducing risk of inappropriate incorporation of uracil into the DNA. Thus, dUTPase is important in DNA replication fidelity.

Mechanisms of regulation of dUTPase activity are currently unknown. DUTPase is a phosphoprotein; however, the significance of this modification, the involved kinases, and the phosphorylated residues have not been determined. Previous studies have shown that while neither of the known vaccinia encoded protein kinases, F10L and B1R, are individually responsible for phosphorylating dUTPase in vivo, both are capable of phosphorylating dUTPase in vitro. This study aimed to use these viral kinases and other commercially available protein kinases to develop an in vitro system of dUTPase phosphorylation with the long-term intent of using this system to elucidate the effects of phosphorylation on the activity of dUTPase. F10L and PKA were used to phosphorylate dUTPase and attempts were made to identify the phosphorylated residues by phosphoamino acid analysis.

The Translocation of Inositolphosphorylceramide across the Lipid Bilayer
Carolin E. Spiegel
Inositolphosphorylceramides, or InsPCers, are a class sphingolipids present in the plasma membranes of plants, fungi, and protozoa. It appears that IPC synthase, the enzyme that catalyzes the formation of inositolphosphorylceramide, or IPC, is located on the cytosolic side of the Golgi membrane. The ultimate destination of IPC is presumably on the exterior of the plasma membrane. Using these two hypotheses as a framework, this thesis explores the translocation of IPC across the lipid bilayer using microsomal and plasma membranes isolated from the golden butterwax bean plant. This was the first reported study of IPC translocation in any organism.

The translocation of IPC is not simultaneous with its synthesis, as demonstrated in assays with phospholipase C, a membrane impermeable, phosphatidylinositol-specific lipase. However, it does seem to occur soon after formation. An exogenous energy source, GTP, enhanced the rate of translocation by 33.3%; ATP was less effective in facilitating translocation. Concentrations as low as 0.2 mM GTP were shown to effectively increase the rate of translocation. It is clear that other translocation mechanisms exist; perhaps these depend on an endogenous energy source or an energy-independent pathway.

Experiments were begun to localize IPC with certainty on the exterior of the plasma membrane. The prepared plasma membrane vesicles were 92% right side out, permitting their use in investigating and quantification of IPC content. Because there is such a small amount of IPC in the plasma membrane, very sensitive methods of detection are necessary. Studies were initiated with one such possibility, phenylisothiocyanate derivative.

Isolation of Two sfp1 Suppressors and Partial Cloning of Three cdc14 Alleles
Elizabeth Wells
CDC14 is a key effector of exit from mitosis in Saccharomyces cerevisiae, and studying the regulation of this dual-specificity phosphatase is crucial to understanding how cells exit from mitosis. Cdc14 mutants display a temperature-sensitive phenotype at 340C, arresting at late anaphase with mitotic spindles extended. Some of Cdc14’s substrates, such as Swi1, Sic1, and Cdh1, are already known. However, the upstream regulation of Cdc14 is still not fully understood. Localization in the nucleolus by the RENT complex is known to be important, as is Cdc10/APC activity. Previous work in the Raymond lab has shown that mutations in the SPF1 gene, encoding a split zinc-finger protein, can suppress the cdc14 allele-specific, which suggests a number of possible models for SPF1/CDEC14 interaction rather than bypass mutations of CDC14 function. While little is known about the regulation of SPF1, it is our belief that study of this novel regulatory element may prove to shed light on regulation of CDC14.

In this study, I rescued three cdc14 alleles into the gapped plasmid gpWR1069 (cdc14-1, cdc14-4, and cdc14-7, from WR148, WR030, and WR024, respectively). The portion of these rescued plasmids containing the cdc14 ORF will, in future research, be made chimeric by restriction enzyme digestion and ligation, and the site of mutations in each allele will be localized. The mutant segments of each CDC14 insert may then be sequenced, and the sequence of each allele compared to its level of sfp1 suppression. In addition, two putative dominant suppressing mutations of afp1-1 and sfp1-2 were found through a mutant hunt for suppressors of sfp1 cold-sensitive phenotype. These mutations may be revertants, but it is possible that they encode bona fide double mutants, whose wild-type function in vivo may be relevant to CDC14
Characterization of a Polychaete Hunchback Homologue
Andrew H. Werbrock
In this study, we attempted to determine whether the function of hunchback orthologues are conserved throughout the annelid phylum. In Drosophila, the gap gene hunchback (hb) encodes a transcription factor possessing a highly conserved N-terminal zinc-finger DNA-binding motifs. Hb is involved in the earliest stages of segmentation and AP pattern formation. In the leech, Helobdella triserialis, an orthologue of hb, LZF2 (Leech Zinc Finger 2), is functionally very different from its insect counterpart and is not involved in segmentation. In order to ascertain whether the function of LSF2 in leeches is shared throughout the annelid phylum we analyzed the protein expression pattern of a putative hunchback homologue, Caphb, in the polychaete Capitella capitata sp. 1, a basal annelid, with a cross-species antibody designed to LSF2. We found that, on a Western blot, the LZF2 antibody binds the N-terminal domains of both Caphb and LZF2, verifying that the antibody is cross-species reactive to Caphb. In early leech and Capitella embryos, the LZF2 antibody is localized to the micromeres, suggesting a common function for Caphb and LZF2 early in annelid development.

Dragonfly Labial Attack and Tadpole Startle Response: A Study with Aeshnidae Larvae and Rana pipiens
David T.O. Walfish
This thesis studies various parameters of the dragonfly labial strike and investigates the factors that influence a tadpole’s chances of escape from predation by dragonfly larvae. The organisms used in this study were dragonflies of the Aeshnidae family and Rana pipiens tadpoles. The strike of the Aeshnid larvae was explored under a variety of circumstances: we tethered the dragonfly and presented inanimate metal probes; we tethered the dragonfly and presented live free-moving tadpoles, and we let the dragonfly hunt tadpoles unimpeded.

Study of the tethered-dragonfly/probe trials yielded important findings about the duration of the forward thrust of the labial attack. We found that the maximum duration of the forward thrust in our trials was less than the published value for maximum duration of the forward thrust. In the free-moving dragonfly/free-moving tadpole trials, we discovered that the duration of the forward thrust in unimpeded interactions with tadpoles is far less than the maximum duration time we calculated, and far less than the minimum estimated latency of the tadpole startle response. This led us to conclude that, contrary to what we had originally thought; the innate startle response possessed by tadpoles does not enable them to avoid being struck by the labial attack.

CHEMISTRY

Determining the Absolute Stereochemistry of Sugar Moieties in Toxicariosides A, B, and C
Karelle S. Aiken
The structures of Toxicariosides A, B and C were determined in the lab of Professor David Richardson, at Williams College. The Richardson group was able to determine the absolute stereochemistry of substituents on the aglycone moieties of these cardenolides. However, with respect to the monosaccharide moieties, the group was only able to resolve the relative stereochemistry of these sugars: A: 6-deoxy-2-O-methylgalactose; B: 6-deoxy-2-O-methylglucose; C: 6-deoxy-2-O-methylgulose. In an attempt to determine the absolute stereochemistry of the sugar moieties, diastereomers of the sugars were synthesized with a chiral and optically active molecule, and then subjected to gas chromatographic analysis. The absolute stereochemistry of toxicarioside sugars can be determined from a comparison of the retention times of these diastereomers to the retention times of diastereomers derived from similar sugars of known stereochemistry. Reactions involved in the synthetic preparation of the sugars for gas chromatography consisted of cleavage of the monosaccharides from the aglycone structure, isolation and butylation with optically pure sec-butanol, followed by permethylation. In this study, these reactions have been developed to give unambiguous and conclusive results. In addition, new approaches to the synthetic preparation of sugars were considered in order to determine if the reactions could be more accommodating of the most probable conditions under which the toxicariosides will be investigated.

The Synthesis and Characterization of Novel Mesogenic Compounds
Michelle B. Dunn
This work focuses on the synthesis and characterization of novel metal-chain complexes in search of metallomesogenic compounds. Using a Co(II) system with ester and amide derivatized pyridine ligands, metal-chain complexes were synthesized, but they converted to tetrahedral, individual molecules upon heating. Both the Mn(II) and Ni(II) systems investigated were generally thermally unstable, decomposing before melting. However, both the MnL2Br2 C10 amide and the NiL2Br2 C10 amide showed mesogenic behavior. Preliminary work a Fe(II) system revealed the facility with which Fe(II) oxidizes to Fe(III). In the future, these complexes must be synthesized and stored under an inert atmosphere for successful synthesis and characterization to occur.

Structural Analysis of SOS Regulation
Biniam T. Gebre
In order to avoid the disastrous affects of DNA damage cells have evolved elaborate machinery tailored to helping them survive this damage. Specifically, cells have evolved strategies, known as DNA damage tolerance mechanisms, which play an important role in allowing them to deal with the consequences of unrepaired damage to their genomes. The SOS regulatory network is a complex system of over twenty genes that, when induced by DNA damage or inhibition of DNA replication, results in the elaboration of these DNA damage tolerance mechanisms. The SOS system, found both in Escherichia coli and Bacillus subtilis, modulates between these two states, which is ultimately either gene expression or gene repression. The LexA protein regulates the toggle between these two states.

LexA's repressor activity has two parts to its functionality; this includes autocleavage (which allows SOS gene expression) and DNA binding (which represses the SOS genes). The LexA activity is realized structurally by the division of the LexA protein into two parts: the carboxyl-terminal autocleavage/dimerization domain and the amino-terminal DNA binding domain. Studying these structural features and the molecular details of LexA's activity should provide further clues as to how the SOS response is regulated. Furthermore, the study of another SOS protein known as UmuD, which shares high sequence homology and presumably similar cleavage activity, should also provide further insight into the LexA autocleavage process.

Molecular modeling and computational methods are employed heavily in this study to extract information about these two proteins in order to gain insight into both the autocleavage process of E. coli UmuD and B. subtilis LexA and the binding of the B. subtilis LexA to the B. subtilis SOS operator consensus sequence. To this end, a structural analysis of UmuD was performed using Molecular Simulation's Insight II modeling suite. Where it was found that UmuD most likely undergoes autocleavage in an intermolecular reaction as a molecular dimer. The structure of UmuD also suggests that RecA might cause a conformational change at Lys98 on UmuD, causing it to push into the active site to catalyze the autocleavage reaction. All the residues in the active site of UmuD and their potential significance have been outlined. Moreover, a model for the B. subtilis N-terminal DNA binding domain was built and then docked on the B. subtilis SOS operator consensus sequence, which provides information about how LexA binds to this sequence and represses SOS gene activation. Similarly, the dimerization domain of the B. subtilis LexA protein was also built using homology techniques and further analyzed for any structural significance that might lend information about the autocleavage process.

Fishing for RNA
Michael D. Hurwitz
Recent discoveries have determined that there are RNA molecules other than transfer RNA that are capable of being aminoacylated in prokaryotes. An ultimate goal in this project is to discover novel RNA structures that may be charged by aminoacyl-tRNA synthetases. In order to commence these studies, it is vital to create a system through which aminoacylated RNA can be extracted from a large RNA pool and identified. Reverse transcription and polymerase chain reactions are utilized to produce large amounts of DNA that correspond to isolated RNA. Successful polymerase chain reaction requires knowing the 3 and 5 ends of a nucleotide sequence. This thesis presents techniques for polyadenylation of the 3 end of tRNA, reverse transcription of RNA with considerable secondary structure, and finally, ligation of a T7 promoter sequence to the 3 end of the resulting cDNA.

A Study of Building a Thin Film of Sulfuric Acid on n-Hexane Soot
Bevan P. Londergan
Heterogeneous chemistry has seen an explosion of interest in the last few decades due to the discovery of the participation of heterogeneous reactions in the mechanisms of some important reactions, such as ozone depletion. Elevated levels of sulfuric acid and depressed levels of sulfur dioxide in jet aircraft exhaust contrails, relative to the levels predicted by the currently characterized reaction mechanisms, have prompted some researchers to hypothesize that the oxidation of SO2 may be facilitated by a heterogeneous reaction involving the soot, a solid aerosol. The adsorption of SO2 onto a dry soot surface has been characterized through previous research in this laboratory. It is now appropriate to study the question of how SO2 interacts with a soot surface on which trace amounts of sulfuric acid are present.

In preparation for the study of this interaction, I have concentrated my efforts on devising an experimental process for creating a thin film of H2SO4 on a cooled soot surface inside a vacuum chamber designed for the infrared spectrographic analysis of surfaces. The formation of a film of H2SO4 on soot is carried out by reacting SO3 and H2O on the soot surface, and this year’s study focused on determining appropriate experimental conditions for the generation of a monolayer acid layer. We use an FTIR and mass spectrometer to monitor the experiments, which range in temperature from –140oC to –65oC. Calibrations have been carried out for determining the thickness of a layer of SO3 through the integration of a characteristic infrared peak. We have succeeded in creating thin layers of acid on soot surfaces, possibly of near monolayer thickness by rough calculations, and we are near to beginning the methodical study of the interaction between SO2 and a sulfuric acid-coated soot surface.

Our relocation to a new laboratory gave us an opportunity to improve upon our extensive experimental apparatus. Among the additions to the lab are a new gas line in a hood, a separate pump room, a new corrosive-gas turbomolecular pump, and a new corrosive-gas mechanical pump to back it up.

Regulation of the Bacillus subtilis SOS System Dual Regulation of recA and Novel SOS Genes with Multiple LexA Binding Sites
Veena Mandava
Expression of the Bacillus subtilis recA gene can be induced by two signals: DNA damage and competence development. The DNA damage pathway has been well-characterized, but the induction of recA during competence development is still not understood. The major competence transcription factor, ComK, interacts in undefined ways with RNA polymerase and LexA on the upstream regulatory region of recA, resulting in transcriptional activation of the recA gene during competence development. To study this interaction, we proposed to perform hydroxyl radical footprinting of recA with the three proteins involved in its induction - ComK, LexA, and RNA polymerase. First, we purified RNA polymerase on a nickel-NTA column using a B. subtilis strain engineered with a His tag attached to the β' subunit. RNA polymerase was unable to bind to the recA promoter, however, because the à subunit was absent from the preparation. Footprinting was attempted with just LexA, but could not be continued without active RNA polymerase.

Novel B. subtilis SOS genes with multiple LexA binding sites were identified in a computer search and were shown to compete with recA for binding of LexA. Four novel genes, yqjW, yqzH, yozL, and yozM, have two SOS boxes, and a third gene, lexA, has three SOS boxes. Band shift assays were performed with these genes to show that each binding site was capable of binding LexA. Results of the band shift experiments suggest that three genes, lexA, yqjW, and yozL, have multiple, active SOS sites. The KDs for lexA and yqjW were found to be 11 nM and 34 nM, respectively.

Finally, we attempted to clone three SOS genes, dinB, dinC, and recA, into an Escherichia coli expression system in order to obtain their protein products. Both dinB and dinC were successfully cloned, but only the DinB protein was produced.

Selective Lithiation of Aromatic Systems
Michelle S. Mourad
The deprotonation of aromatic species often results in a mixture of isomers, and thus poor regioselectivity upon reaction with electrophiles. Lithium diethylamine was used to facilitate an equilibrium between the two anions formed that might favor the more thermodynamically stable anion and thus improve regioselectivity. The compounds 3-methyl-2-thiophene-carboxylic acid and 1-methyl pyrazole were most extensively studied. In their alkylation with methyl iodide, acetone and benzaldehyde, deprotonation with lithium diethyl amine as compared to n-butyl lithium or lithium diisopropylamide gave improved regioselectivity for these two systems.

The Synthesis and Study of Models for the Active Site of Liver Alcohol Dehydrogenase
Megumi Onishi
The mechanism of catalysis by Liver Alcohol Dehydrogenase (LADH) has not been completely elucidated. Furthermore, the importance of zinc(II) in the active site, as well as the possible significance of the two cysteine and one histidine ligands coordinated to the metal have not been well defined. Synthetic models whose ligands bind in a distorted tetrahedral geometry will allow for studies into the role of zinc(II) at the active site of LADH. Steps toward the synthesis of bi- and tri-dentate ligands to model the active site are described, utilizing 2-methyl-4-tert-butyloxazole, as well as organic and inorganic linker molecules, including benzophenone, 2,2'-dicholoro-4,4',5,5'-tetramethylbenzophenone, and phenyldichloroborane. Molecular modeling studies suggest that the target ligands will bind to zinc(II) with structural parameters similar to the active site of LADH.

The Role of RNA Structure in tRNA Interactions with Aminoacyl-tRNA Synthetases
Michelle Pacholec
In contrast to the uniformity observed in cytoplasmic tRNAs, there is a great deal of structural variation in animal mitochondrial tRNAs. The most extreme cases are observed in the nematodes C. elegans and A. suum, where 19/20 of the tRNAs have their entire T-stem/loop and variable loop deleted and replaced with a short 6-12 nucleotide TV-replacement loop. In order to study these truncated tRNAs, hybrids that mixed and matched elements from both the cytoplasmic E coli tRNAAla system and the C. elegans mitochondrial tRNAAla system, were created. Determination and comparison of the rates of aminoacylation of these chimeras by both E. coli and C. elegans mitochondrial alanyl-tRNA synthetase, both of which have been expressed in a plasmid vector, would allow one to determine what structural elements are important for charging. In this thesis, all of the chimeras were tested for aminoacylation by E. coli AlaRS. As expected, this enzyme aminoacylated neither C. elegans mt-tRNAAla nor any of the hybrid constructs containing the C. elegans acceptor stem. Surprisingly, however, hybrids that preserved the E. coli acceptor stem, but contained other C. elegans structural elements were not aminoacylated by E. coli AlaRS. These results indicate that deletion of the T-stem/loop and its replacement with the TV-loop negatively effects charging. Two possible reasons for this lack of aminoacylation are discussed, including the possibility that these chimeric tRNAs are adopting non-canonical tertiary structures that inhibit E. coli AlaRS from accessing and hence charging the acceptor stem.

Cloning and Purification of Bacillus subtilis ComK, and Expression Profiling of Unknown SOS Genes
Amish A. Shah
Exposure of Bacillus subtilis to a variety of DNA-damaging agents results in the induction of the global “SOS response.” Expression of the genes in the SOS regulon are controlled by the LexA protein. LexA acts as a transcriptional repressor of these unlinked genes by binding to specific sequences (SOS boxes) located within the promoter region of each LexA-regulated gene. Alignment of known LexA binding sites found in the B. subtilis chromosome reveals a consensus of 5'-GAACN4GTTC-3'. By using this consensus sequence as a search criterion, Lovett, et al. has recently performed computational searches of the entire B. subtilis genome to identify novel LexA-regulated genes. These searches identified a total of 33 potential LexA-regulated genes, including some previously characterized LexA-regulated genes. Using electrophoretic mobility shift assays, 18 of the 33 were found to bind LexA. This study used gene macroarrays and expression profiling to investigate whether these 18 putative SOS genes were expressed during a SOS response. Results suggest that these 18 genes are, in fact, expressed at significant levels during SOS response, thereby allowing us to identify 18 novel LexA-regulated genes. The potential function of each newly identified LexA-regulated gene is discussed.

ComK is a 23 kD competence transcription factor which drives the development of competence in B. subtilis, yet also activates the transcription of recA. The RecA protein is required for induction of the SOS DNA repair system and general recombination in B. subtilis. In order to investigate the relationship between LexA, which functions as the repressor of SOS regulon, and ComK, which acts as the transcriptional activator of recA during competence-development, large quantities of highly purified ComK protein are needed. ComK was amplified from chromosomal B. subtilis DNA and cloned into an Escherichia coli expression vector. Preliminary results of the protein induction indicate successful cloning, although further investigations must be performed to optimize a purification protocol.

Progress toward the Synthesis of (+)-Pacifigorgiol:
Formation of the Tetrahydroindene Skeleton
Carolyn A. Stickney
(+)-Pacifigorgiol is a sesquiterpenoid compound that has been isolated from the gorgonian soft coral Pacifigorgia adamsii; its enantiomer, (–)-pacifigorgiol, has been isolated from the essential oil of the plant Valeriana officinalis. As the former has shown evidence of ichthyotoxicity, it is posited to be a defense mechanism for the coral from which it was isolated. In 1982, an 11-step racemic synthesis of pacifigorgiol was completed by the Clardy group; shortly thereafter, an asymmetric synthesis of (–)-pacifigorgiol was accomplished in the same group; the yield for their sixteen-step synthesis was 15%. In this research we propose a twelve-step asymmetric synthetic scheme applicable to the construction of either (+)-pacifigorgiol or (–)-pacifigorgiol wherein the key step is a transition metal-catalyzed [4+2] cycloaddition. This step, which is the focus of this work, forms the tetrahydroperindene skeleton of the pacifigorgiol molecule in a single step from an acyclic precursor, resulting in the directed establishment of two stereogenic centers. The following research describes the successful optimization of many of the reactions leading to formation of the substrate for the key cycloaddition step. In addition, a viable catalyst system, Ni(acac)2/Et2AlOEt, has been found for the cycloaddition reaction, and evidence has begun to be gathered in support of the accomplishment of the cycloaddition.

COMPUTER SCIENCE

Automatic Generation of Penrose Empires
Jason B. Healy
Penrose Tilings are infinite tilings that cannot tile the plane in a periodic manner. They are of interest to researchers because they may model a new type of matter called “quasicrystals.” Being able to manipulate and study Penrose Tilings easily is important, and that is the primary goal of this research. Although Penrose Tilings are infinite, we would like to be able to store them in a finite device, such as a computer, so that they may be more easily studied. The primary aim of this research is to attempt to discover some of the underlying structure of Penrose Tilings, so that the tilings can be reduced and stored in an efficient, finite manner.

In addition to being able to store tilings, this research also aims to learn more about constructing the tilings themselves. Because we are reducing an infinite amount of data to a finite amount of information, there will necessarily be some computation required to reconstruct the information that is not explicitly stored. This research will also investigate methods of constructing Penrose Tilings from a small amount of initial information. The algorithms developed and discussed in this work allow us to represent Penrose Tilings as a small set of finite variables and then compute any arbitrary information about the tiling on demand. In this way, we can reconstruct as much of any tiling that we desire, without needing to store the entire tiling. It is hoped that the methods used will allow a more detailed study of Penrose Tilings to take place in future research.

Co-circular Point Sets and the Minimum Weight Triangulation
Reed L. Townsend
We investigate the minimum weight triangulation of co-circular point sets and demonstrate a large subset for which the minimum weight triangulation can be found in O(n log n) time. Generalizing our approach, we present strong evidence that the general problem of finding the minimum weight triangulation of co-circular points is a more difficult problem and that our previous technique of searching for improving moves on the dual tree may not be the best approach.

GEOSCIENCES

Petrogenesis and Correlation of the Mid-Tertiary Upper Bonanza Tuff, Central Colorado
Rebecca K. Atkinson
The mid-Tertiary upper Bonanza tuff of south central Colorado is the only rhyolitic unit associated with the intermediate volcanic units of the Bonanza caldera: the Rawley andesite, the lower Bonanza tuff (a dacite), and the upper andesite. Two other rhyolitic units are also associated with the caldera: the Spring Creek pluton and the Porphyry Peak rhyolite, the latter an exogenous dome on a ring fracture of the caldera. The Bonanza caldera is located between the two major mid-Tertiary volcanic fields of central Colorado—the San Juan and Thirty-nine Mile—and has previously been considered a part of the San Juan volcanic field. However, its geographic separation and greater age suggest that it is more closely related to the Mt. Aetna and Grizzly Peak calderas, which are aligned with the Bonanza caldera along the western edge of the Rio Grande rift. These calderas are the probable sources of some of the ash-flow tuffs of the Thirty-nine Mile volcanic field, which lies to the east.

The upper Bonanza tuff is petrographically a phenocryst-poor rock with sanidine as its dominant mineral; notably it contains no quartz phenocrysts. While these features distinguish it from the other units of the Bonanza caldera, it is similar to rhyolitic ash-flow units of the Thirty-nine Mile volcanic field, especially the Wall Mountain and Gribbles Park tuffs. Geochemically, the upper Bonanza tuff is also distinct from the other intermediate units of the caldera, but it closely resembles, in both major and trace element composition, the Spring Creek pluton and Porphyry Peak rhyolite of the caldera.

The petrogenesis of the upper Bonanza tuff magma is still problematic, as it overlies a dacitic unit, the lower Bonanza tuff, contradictory to the expected stratigraphy produced from a zoned magma chamber. One possible origin of the upper Bonanza tuff magma is by pure fractionation of a less evolved magma, such as the lower Bonanza tuff. However, the distinct separation of trace element ratios in the lower and upper Bonanza tuff argues against this possibility, as does a petrogenetic model which postulates the lower Bonanza tuff as a parental magma. When used to recalculate the major element chemistry of the upper Bonanza tuff, this model produced a daughter liquid of a dacitic-rhyodacitic composition, proving that the upper Bonanza tuff is not derived by pure fractionation of the lower tuff and implying that direct partial melting of the crust may be involved in the generation of the upper tuff.

In a regional perspective, the upper Bonanza tuff is petrographically and geochemically similar to the Wall Mountain and Gribbles Park tuffs of the Thirty-nine Mile volcanic field. However, because it differs in age and paleomagnetic signature from the Wall Mountain tuff, only the Gribbles Park tuff may be actually correlative with the Bonanza tuff. This suggests the possibility that the Bonanza caldera is actually the source of the Gribbles Park tuff as well as the upper Bonanza tuffs and that late explosive activity that produced the tuffs also produced the rhyolites of the Spring Creek pluton and Porphyry Peak dome.

Geochronologic, Structural, and Tectonic Analysis of the Itremo Group, Central Madagascar: A Look at Deformed Metasediments and Paleo-Reconstructions from 800-500 MA
Carla B. Chokel
The Itremo Group of central Madagascar is composed of metamorphosed and deformed quartzites, pelites, and marbles that exhibit a strong north-south structural trend. This study applies geochronology and structural techniques to interpret the tectonic history of the Itremo Group and paleoposition of Madagascar prior to Gondwana formation. Results from U-Pb SHRIMP dating indicate that deposition of the sediments began no earlier than 1722 Ma. U-Pb data from igneous rocks intrusive into the metasediments (Handke, et al., 1999) indicate that deposition of the Itremo Group was complete by 790 Ma. U-Pb SHRIMP analysis of detrital zircons suggests a major lead-loss event at or around 600 Ma which is interpreted to coincide with the major metamorphic event.

Structural analysis of lithologic maps and satellite images highlights steeply dipping structures that are a result of ductile deformation. Based on structural trends seen in SPOT and Landsat images of the Itremo region, the degree of deformation diminishes to the east of these structures, where several dissected nappes are located. Also present in the Itremo region are a series of large-scale sigma-type complexes (tectonic fish) and shear zones, all of which indicate sinistral movement. Structural analysis indicates that metamorphism and deformation occurred as a consequence of a westward-directed continental collision, possibly between Madagascar and India. If this is the case, then Madagascar may have been contiguous with Africa during the Proterozoic before the amalgamation of Gondwana.

Petrological and Mathematical Analysis of Polymict Conglomerates
Patricia G. Hines
There are two main types of conglomerates: those that contain polymict material and those composed of quartz pebbles. Currently, there are no means to quantify the amount of pressure solution and diagenesis in conglomerates (Cant and Ethier, 1984), but Gutmann’s (1999) thesis on quartz pebble conglomerates and this study on polymict conglomerates are first attempts to quantify diagenesis and pressure solution. Quartz pebble conglomerates may form either by breakdown of weaker clasts during transport, or post-depositionally by preferential breakdown of weaker clasts during diagenesis. If polymict conglomerates generally demonstrate low levels of diagenesis relative to high levels seen in quartz pebble conglomerates (Gutmann, 1999), it is reasonable to assume that diagenesis may play a significant role in the formation of quartz pebble conglomerates. On the other hand, if polymict conglomerates demonstrate higher or comparable levels of diagenesis, we would infer that the differences between quartz pebble conglomerates and polymict conglomerates are not due to diagenetic processes, and that quartz pebble conglomerates form at deposition.

In this study on polymict conglomerates from Ireland and Norway, techniques and methods established by Gutmann (1999) were applied. This includes line counting of thin section, point counting in the field, fourier and fractal analysis, and application and renovation of the Pressure Solution Index (PSI).

Textural differences between the two sets of conglomerate types (Gutmann 1999) suggest that the quartz pebble conglomerates have undergone more mass transport. In addition, the polymict conglomerates have relatively lower levels of interpenetrating and nested contacts than the quartz pebble conglomerates, indicating that the polymict conglomerates are less pressure solved and less diagenetically altered. The results of my research do not, however, conclusively support a diagenetic origin for quartz pebble conglomerates. Grain behavior (rheology), rather than diagenetic processes may be responsible for the significant textural differences between polymict conglomerates and quartz pebble conglomerates.

Paleoecology of Upper Pleistocene Coral Reefs Based on Morphology and Fossil Assemblages, Baja California Sur, Mexico
Cordelia R. Ransom
During the last interglacial, oxygen isotope substage 5e, eustatic sea level was 6 ± 2 m higher than the present (Ashby, Ku, and Minch, 1987). Upper Pleistocene carbonate terrace deposits associated with substage 5e are widespread along the current Gulf of California coastline in Baja California Sur, Mexico. Coral reef colonies, composed primarily of Porites californica, dominate three carbonate localities (117.9-125 ka) in the eastern central coastal region at Punta Chivato, Punta San Antonio, and Punta El Bajo. Each of these localities is unique based on the cardinal orientation of the preserved reef and morphology of Porites californica. Morphospace analysis, coral dating, and comparison of associated fossil assemblages are used to reconstruct the paleoecology of the coral reefs. Factors affecting upper Pleistocene coral reef ecology include the semi-monsoonal wind pattern of the gulf (Bray and Robles, 1991), storm events, and the interglacial climate.

Uranium-series dating provides a date of 117.9 ± 0.6 ka for coral colonies from Punta Chivato. In order to record coral morphologies and associated fossil assemblages at Punta Chivato, 22 census grids were surveyed along the baseline. The reef boundaries were determined by setting up three 360-375 m-long transects that perpendicularly bisect the baseline. At total of 51 pits (ave. 0.25 m-deep) were excavated along these transects in order to map parts of the buried reef. Living non-reef coral colonies were recorded offshore Punta Chivato using mask and snorkel and census grids. Eight census grids were taken from Punta San Antonio and a total of 36 census grids were employed at Punta El Bajo. Panel diagrams were constructed based on stratigraphic relationships and census grids for the reef exposures at Punta Chivato and Punta El Bajo.

The coral reef at Punta Chivato sits in a topographic bay opening to the south on the south side of the Punta Chivato promontory. Bordered to the north, east, and west by Pliocene and Miocene ridges, the reef facies visibly overlies Miocene volcanic breccia and adjacent Pliocene conglomerate. The head of the bay is bordered by lagoonal deposits extending approximately 100 m to the north. Within the reef itself are 3-4 generations of bouquet-shaped Porites californica, in various states of preservation ranging from in situ to jumbled. The coral heads average 12 cm in height, reflecting relatively young coral colonies. The reef contains a rich associated fossil assemblage representing 78% of the total 68 recorded marine invertebrate species from the three localities. Coral generations are divided by terrestrial sediments and rhodolith algae indicative of periods of heavy run-off or storm generated bottom currents resulting in successive kill-off of coral colonies.

Punta San Antonio features an abandoned Upper Pleistocene embayment that opens to the Gulf of California from east to west. The embayment margins are defined by stratified Pliocene limestone and/or Miocene tuff overlain by a 1-m thick boulder deposit, which is extensively encrusted by coralline algae. A small cove occurs at the eastern termination of this bay and contains a single generation of Porites californica, comparable in height to the coral colonies at Punta Chivato, but with a distinctively rotund morphology. Single finger-shaped coral colonies appear in growth position in the larger embayment outside the cove. The variation in morphology reflects the subdued waves that are refracted around the points, into the cove. The cove deposit contains an associated fossil assemblage of moderate diversity representing 21% of total recorded species.

At Punta El Bajo, a 2-m high north-facing exposure, with coral reef deposits runs discontinuously for 290 m along the present high tide line and is bordered to the east and west by higher topography extending into the subtidal. The deposit contains moderate numbers of marine invertebrates (31% of total recorded species) and a single generation of high arborescent Porites californica ~1.6 m tall, indicating longer-lived corals than seen at the other two localities. Another coral reef deposit, >100 m long, is located on the east side of the eastern point. This community is capped by a massive andesite boulder bed reflective of a severe rain storm event or a transition to a prolonged wetter climate. The coral in the eastern reef are much more robust with branches at least twice as thick and the associated biota twice as large as found among and along the neighboring western ridge. The fossil assemblage associated with the east reef is minimal representing 18% of the total recorded species. The more robust coral community developed on a distal spur from the main N-S coastline in a setting fully exposed to northerly winds, whereas the arboral community developed in a more protected, proximal environment. Observed interfingering of carbonate reef deposits and massive conglomerates suggest transitions between dryer and wetter climates related to glacial cycles. Notably, no living Porites californica reefs appear offshore these Upper Pleistocene deposits. Therefore, climate during the last interglacial in the Gulf of California appears to have been significantly different than the present and can provide insight into current trends in global climate change and the health of living coral reefs.

Fire and Ice: The Geomorphic History of Middle Boulder Creek as Determined by Isotopic Dating Techniques, Colorado Front Range
Taylor F. Schildgen
Cosmogenic 26Al, 10Be, 14C, and 36Cl dating of fluvial fill terraces and other geomorphic surfaces along steep canyons of the Colorado Front Range provides a temporal framework for analyzing fluvial response to sediment budget perturbations. Fluvial terraces > 4 m above the Middle Boulder Creek channel (grade) record activity during late Pleistocene time. Terraces < 4 m above grade and alluvial fans preserve evidence for system responses to Holocene climate change. The fluvial processes that these surfaces record contributes to a comprehensive understanding of the long-term evolution of Front Range canyons.

Cosmogenic exposure ages of boulders on glacial moraines near Boulder Canyon are consistent with glacial chronologies derived from nearby regions. Samples from Bull Lake moraines have minimum average 10Be and 26Al ages of 101 ± 21 ka and 122 ± 26 ka, comparable to other age estimates of 150 to 100 ka for moraines at sites in Wyoming, southwest Montana, and other regions of Colorado. Pinedale moraines near Nederland have average model 10Be and 26Al ages of 16.9 ± 3.5 and 17.5 ± 3.6 ka, consistent with other cosmogenic exposure ages and 14C estimates of 35 to 15 ka reported elsewhere in the Rocky Mountains. These new age estimates, considered together with field relationships, suggest that late Pinedale glaciers were nearly as extensive as those active during earlier Pinedale and Bull Lake advances.

The fluvial response to glaciation in the Front Range can be analyzed using regional and local late Pleistocene glacial chronology and cosmogenic exposure age estimates for fill terraces in Boulder Canyon. Results from Boulder Canyon show that terrace heights above grade can be divided into (1) Bull Lake (> ~100 ka) at 15 to 20 m above grade; (2) Pinedale (30 to10 ka) at 4 to15 m above grade; and (3) Holocene age at < 4 m above grade. Better-preserved terraces of latest Pleistocene age suggest that variations of height above grade reflect short-term fluctuations in the river profile during periods of rapidly changing stream load and power. Net river incision apparently occurred during transitions to interglacial periods. Soil development and stratigraphic position, used with limited cosmogenic and 14C dating suggests that ~ 130 ka terraces in Boulder Canyon correlate with the Louviers or Slocum Alluviums, and that 32 to 10 ka fills in the Canyon correlate with the Broadway Alluvium on the High Plains east of the Front Range. Middle to late Pleistocene incision rates represented by high terraces in Boulder Canyon are higher than early Pleistocene rates, possibly as a result of east to west migration of a knickpoint on Middle Boulder Creek.

Low terraces (< 4 m above grade) and alluvial fans in Boulder Canyon record Holocene deposition resulting from forest fires related to climate change. Forest fires destabilized small (0.5-1.0 km2) tributary catchments within the canyon during the early and late Holocene, producing episodes of alluvial deposition. Alluvial fans accumulated at rates between 0.2 and 95 Mgha-1yr-1 depending on whether we assume constant or episodic sediment accumulation rates. Alluvial deposition and associated forest fire occurrence in Boulder Canyon correlate with a late Holocene climate characterized by conditions drier than at present. Fire and deposition is also correlated with the warm and wet early Holocene climate which likely induced widespread vegetation growth to fuel extensive fires during occasional dry periods. Alluvial fans and fluvial terraces appear to be effective in preserving evidence of past climate change, and of processes that have contributed to the evolution of the Colorado Front Range.

MATHEMATICS

Uniqueness in m-Dimensional Triangle Sequences
Tegan Cheslack-Postava
In the generalization of continued fractions introduced by Garrity, each point in an m-dimensional simplex is represented by a sequence of nonnegative integers. After introducing the algorithm for generating these sequences, we show that the representation map is in general not injective. We use the notions of partition simplices and associated dimension to investigate the set of points identified by an m-triangle sequence.

Strict Minimality of Alternating Knots in S x I
Thomas Fleming
In the late 1800’s Tait conjectured that for knots that lie in the plane, a reduced alternating projection has the smallest possible number of crossings for any projection of that knot, and that any non-alternating projection must have more crossings. This fact was proven in 1984 by Kaufmann, Murasugi, and Thistlethwaite. In the summer of 1999, the Colin Adams directed Knot Theory SMALL group of Fleming, Levin and Turner was able to prove that if the knot projection lies on a surface (such as a torus) and the knot lies in a layer around that surface (the surface cross an interval), then a reduced alternating projection has the smallest possible number of crossings for any projection of that knot. We will extend this work to prove that for a knot in a surface cross an interval, a reduced alternating projection of the knot must have strictly fewer crossings than a non-alternating projection. We will use arguments based on a generalized Kauffman bracket polynomial, Menasco-type geometric arguments, and covering space techniques.

Applying a Bayesian Hierarchical Model to a Data Set Consisting of Hospital Mortality Rates
Cory Heilmann
Bayesian hierarchical modeling is often applicable to data sets where the data originate from many different entities, each of which measures a similar quantity. Examples of these data sets are students’ test scores from different schools and mortality rates from different hospitals. This sort of modeling is particularly useful when we wish to estimate means and variances of each entity, but some of the entities have low numbers of observations, and thus the maximum likelihood estimator is unreliable. This thesis uses a Bayesian hierarchical model on a data set consisting of the mortality rates from organ transplants in 131 hospitals. We will rank the hospitals according to their predicted mortality rate, and also decide whether the mortality rates of small hospitals appear to be larger than the mortality rates of large hospitals.

A Structural Analysis of the Triangle Iteration
Adam Schuyler
Classically, it is know that the continued fraction sequence for a real number ± is eventually periodic if and only if ± is a quadratic irrational. In response to this, Hermite posed the general question which asks for ways of representing numbers that reflect special algebraic properties. Specifically, he was inquiring about possible generalizations of the continued fraction. In this paper, we will study the triangle iteration, a two-dimensional analogue of the continued fraction. We will take a primarily geometric approach and look at the probabilities of the occurrences of certain sequences.

PHYSICS

An Investigation of Non-Linear Dynamics in a Modelocked Ti: Sapphire Laser
Mark R. Acton
We present research into the non-linear dynamics of a modelocked Ti:Sapphire laser. We employ non-linear analytic tools to describe and characterize non-linear dynamics. We present the first known demonstration of single transverse mode chaos in the laser. We also hypothesize a possible mechanism for generating the non-linear transition associated with this chaotic regime. A computer model is presented that can test the validity of this hypothesized mechanism.

Hyperfine and Rotational Structure in Sodium Dimers: Ultracold Photassociation to the Molecular State Na2 1g (3S + 3P3/2)
Ginel C. Hill
Ultra-cold photoassociation spectroscopy was used to investigate the transition between rotation-dominated structure and hyperfine-dominated structure in spectra of a specific Na2 molecular state, the 1g (3S + 3P3/2). High-resolution spectra of representative vibrational levels from ν = 50 to ν = 75 displayed distinct rotational levels with increasing hyperfine splittings over this range. A novel experimental technique was used to distinguish between odd and even I hyperfine lines in the 1g spectra by employing a doubly-excited 0u state as the ionization pathway. The observed hyperfine lines were fit with Wigner threshold law lineshapes to extract the natural line positions, which revealed a breakdown of the Wigner threshold law for Á-wave collisions at temperatures T250μK. Finally, a simple model for the competition between hyperfine and rotational structure presented by Wang, et. al., Phys. Rev. A 57, (1998) was used to construct a theoretical spectrum for the data. This model matched spectral line positions within 3-4 MHz and labeled each line with quantum numbers consistent with the experimental odd and even I designations.
Quantum Mechanics and Phase Space
Anthony M. Ndirango
Phase space, whose axes represent position and momentum variables, is a concept from classical physics that is not normally included in formulations of quantum mechanics. This is because the position and momentum of a quantum particle cannot simultaneously take definite values. Nevertheless, there are a number of interesting issues concerning the relationship between quantum mechanics and phase space, some of which are explored in this thesis. In particular, we prove the “trace-area theorem,” which relates a geometrical quantity from quantum mechanics (the trace of a product of operators) to a geometrical quantity in classical physics, namely, the area enclosed by a path in phase space. We show that this theorem can be used to generalize some of the features of phase space to discrete quantum variables such as spin.

Entangled Chains & Rings
Kevin M. O’Connor
Entanglement is the resource underlying many potentially useful technologies including quantum cryptography, quantum teleportation, and quantum computation. In this thesis we explore how this resource can be shared “optimally” in entangled chains and rings of particles. We define an “optimally-entangled” chain or ring state to be one in which the minimum nearest-neighbor entanglement in the chain or ring is maximized. Using certain strategies that we conjecture are useful for finding optimally-entangled states, we present our findings for several finite chains and rings as well as what we believe to be formulas for the optimal concurrence of two classes of ring states. We conclude by considering the entanglement sharing properties of physically-realizable rings of spin-1/2 and spin-1 particles and showing that these are, under certain restrictions, optimally-entangled.

Measuring the Stark Shift in the Thallium 6P1/2 7S1/2 378 nm Transition
Andrew J. Speck
This thesis details the apparatus, which includes electric field plates, an atomic beam, and an ultraviolet laser system, and procedures necessary to measure the Stark shift in the 6P1/2 7S1/2 transition in atomic thallium. The operation of the experimental apparatus needed to make this measurement is discussed and results from simulating the proposed experiment are given. Details of a method to frequency stabilize a diode laser using a Fabry-Perot cavity to transfer frequency stability from a stabilized laser are described.

PSYCHOLOGY

What Video Games May Do: An Empirical Examination of the Effects of Violence and Sexist Content in Video Games
Emily Eustis
The present research examined the effects of violent and sexist content in video games on the attitudes and beliefs of male college students (N = 93). Previous research has shown that media violence and pornography can negatively impact an individual. The sparse available research on the effects of electronic games has indicated that violent video games may increase aggression in the short term for younger boys, but beyond this immediate effect, little else is known. The goals of this experiment were to confirm previous findings that violent video games increase state hostility, and to determine whether sexist video games influence an individual’s sexist beliefs. Participants came to the laboratory and played one of four video games: a sexist game, a violent game, a sexist and violent game, or a non-sexist/non-violent game. Approximately every 6 minutes, they paused the game and completed a number of measures related to hostility and sexism. Results indicated that highly violent video games increased state hostility and arousal and that participants’ trail hostility predicts participants’ state hostility, preference for sexual material, sexism, and attitudes towards women. Participants who played games with sexist content exhibited more sexism on the Mate Preference Questionnaire and the Modern Sexism Scale. They also had more sympathy for an individual who committed a murder of passion. The effects of the sexist game tended to be more pronounced among participants who were high in trait hostility. Therefore, the results suggest that not only do violent video games tend to increase hostility, but also that sexist video games tend to increase sexist attitudes and judgements, particularly among people who are high in trait hostility.

Postnatal Stress and Hippocampal Plasticity: Implications for Learning and Memory
Deborah F. Frisone
This study examined the effects of early stress on the development of learning and memory in a spatial navigation task. Long Evans hooded rats were socially isolated (SI) for six hours daily at postnatal (PN) days 15-21 to determine the effects of early stress on hippocampal function. Blood samples were collected one hour after separation on PN 18 and plasma corticosterone (CORT) was assayed. The Morris water maze (MWM) was used to test spatial learning and memory at PN 22-24 and in adulthood (mean age PN 92-94). SI subjects weighed significantly less than controls at PN 22, but not at PN 15, 25, or 100 indicating that any weight loss due to SI was not of an inherent or permanent nature and most likely did not affect performance on the MWM. SI subjects showed impairments on the MWM at PN 22-24, with mean latency to the platform differing significantly from controls on the first day of testing. In adults, there was a significant interaction between test day, trial number, sex, and condition. SI subjects tended to show significant enhancements on the MWM, as compared to controls. These results are discussed in light of previous findings related to the study of neural development, stress, and hippocampal morphology and function.

Male Emotional Expression: When Sadness Becomes Anger
Stephen M. Gray
This study examined 1) the influence of social context on males’ expression of sadness and 2) the relationship between expressed sadness and subsequent anger expression. Sadness was induced in 94 college males, who were then brought into a room with two confederates (2 males or 2 females) and asked to talk about their sadness following either expression of sadness by one confederate (while the second confederate either listened in a manner accepting of emotional expression or in a neutral manner) or withholding of sadness expression by the speaking confederate. Participants were then issued an anger manipulation. Results showed that participants expressed the most sadness in the presence of expressive and accepting males. Their anger expression was recorded and coded and was found to be negatively correlated with the amount of sadness expressed during the group interaction. Clinical and research implications are discussed.

Ah Who Yuh Dey Call Mad Man? Young Jamaican’s Attitudes toward Mental Illness
Dahra N. Jackson
Two studies were carried out to assess young Jamaicans’ attitudes and opinions about mental illness. Study 1 presented male and female high school students (N = 1223) with a video interview of a male or female confederate seeking a job. The job candidate was presented as either 1) a normal person or as 2) having had a history of mental illness resulting from a “chemical imbalance” or as 3) a result of a “dysfunctional family life”. Subjects completed a 9-item social distance scale. As predicted, subjects desired more social distance from the job candidate who was presented as having illness vs. not, and the most social distance from the job candidate who was presented as having mental illness resulting from a dysfunctional family life. Contrary to hypotheses, neither the gender of the “job candidate” nor of the subject had and effect on desired social distance. In study 2, the same subjects completed the Opinions about Mental Illness Scale; half of them completed the standard scale and half completed it with the wording “mentally/mental illness” replaced by the more colloquial “mad/madness” in each item, in order to examine the effects of such language. Subjects in the “mad/madness” conditioned expressed more socially restrictive attitudes than did those in the “mentally ill/mental illness” condition. Females expressed more authoritarian attitudes than did males, and were more benevolent towards the mentally ill than were males. There was no gender difference in socially restrictive attitudes. Exploratory analyses of the effects of other demographic variables revealed much more authoritarian, socially restrictive, and less benevolent opinions about mental illness among lower socioeconomic class students and less authoritarian, and less benevolent attitudes among urban vs. rural students, with interesting interactions of gender and these variables. Comparison of the Jamaican sample to US samples in the literature revealed more authoritarian, more socially restrictive, but also more benevolent attitudes in the former. Implications for public education and further research are discussed.

The Effect of Expert Testimony on Confession Evidence in the Courtroom
Lisa D. Knappen
The present research studied the effect of expert testimony on confession evidence in the courtroom. Specifically, it aimed to determine whether expert testimony would help jurors be more sensitive to police interrogation techniques that increase the risk of false confessions, or if the testimony would overwhelm jurors, causing them to discount confessions that were not unreasonably coerced. Two studies were conducted that were conceptual replications of each other. In both experiments, mock jurors were randomly assigned to one of seven groups: voluntary confession condition with or without an expert (in these conditions, the defendant signed the confession voluntarily); physically coerced confession condition with or without an expert (in these conditions, the defendant initially denied the charges, but eventually signed the confession after he was physically coerced); psychologically coerced confession condition with or without an expert (in these conditions, the defendant initially denied the charges, but eventually signed the confession after he was psychologically coerced); and a control, no-confession group. Mock jurors viewed a videotaped summary of an actual trial and afterward completed a case-related questionnaire. The results in both studies confirmed previous findings that confession evidence is extremely influential in determining a defendant’s guilt. The results from Experiment 1 did not confirm the hypothesis that the presence of an expert would sensitize mock jurors to psychologically coercive interrogation techniques. However, results from Experiment 2 indicated that expert testimony sensitized jurors to psychological interrogation pressure, but that the testimony did not overwhelm mock jurors in the other conditions. The findings support the notion that expert testimony should be admitted in cases involving disputable confessions.

The Effects of Pre-Weaning Social Environment on Learning, Locomotor Activity, and Play Behavior in Juvenile Rats
Meghan N. Moscati
This study examined the role of early social environment on the learning, activity, and play behavior of juvenile rats. Pregnant Long Evans hooded female rats were housed in one of four housing conditions throughout gestation until weaning at postnatal day 25: “Sire” (biological father), “Aunt” (unrelated, nulliparous, adult female), Large Cage (larger cage also used in Sire and Aunt to accommodate two adults), or Small Cage (standard breeding cage). At post-natal day (PN) 32, sixty-eight subjects began training in the Morris Water Maze where the latency to find the platform was recorded. The remaining 74 subjects were tested singly for activity levels for three consecutive days and then on the fourth day were placed in the activity chamber with a stimulus playmate and observed for quantifiable play and social behaviors (no contact, sniffing or following, grooming self, dorsal contact, crossovers, wrestling, pinning, and getting pinned). Significant effects across condition were not found for the Morris Water Maze learning task or in activity levels. There were significant effects across condition for some of the observed play behaviors. Subjects raised in the Sire condition spent significantly less time sniffing and following the stimulus playmate than did subjects raised without an additional adult, regardless of cage size. There was a sex effect for crossovers where females made significantly more crossovers than males across all four conditions. The data suggest that the early social environment may not be as important for later learning and activity levels, although a different learning task may be able to pick up more subtle differences. The early social environment did appear to be of minor importance in later social behaviors, and further research might investigate hormonal changes that could be resulting from differences in socialization as well as alterations in adult social behaviors.

The Phenomenology of Custody
Jason C. R. Oraker
The present study investigated perceived freedom in custody-like situations. In the Preliminary Study, 44 participants read 20 vignettes, varying indicia of custody (as ruled on by the courts), and made subsequent judgments about the freedom of individuals, in each, to leave. While results indicate that people are sensitive to factors signifying custodial situations, in all situations, they see others as more free to leave than they see themselves. In Study 1, 81 participants watched either a low, moderate, or high custody videotaped interrogation and subsequently made objective and subjective judgments concerning the actor’s freedom to leave. In the moderate custody condition, judgments of whether the actor was free to leave and whether he thought he, himself, was free to leave, differed, with people seeing him as free to leave, but unaware of that objective reality. Even in the high custody condition, where people believed that the actor did not perceive freedom to leave, 40% of participants still saw him as free to leave. In Study 2, 81 participants watched either a low or high custody videotaped interrogation and, in addition to the same judgments from Study 1, made reasonable person judgments – assessing custody as though they, themselves, were suspects. The reasonable person judgments provided a new outcome to the custody question. These results suggest that how one asks the question concerning whether an individual is in custody greatly affects the answer, and that judges and jurors, who are ultimately ruling on these decisions, should be adequately informed.

The Magnitude Effect in Intertemporal and Risky Decision Making: Fact or Artifact?
Jennifer C. Page
Existing data do not tell us why we observe a magnitude effect in intertemporal or probabilistic decision making. Three studies tested the possible explanations of rounding artifacts, a ceiling or floor effect, and a constant-difference effect. In Experiment 1, we used a second-bid auction procedure in which participants “bid” their subjective value of the delayed reward for four reward amounts: $11, $14, $21 and $24. All bids were for real monetary rewards. In Experiment 2, we also looked at the magnitude effect in intertemporal decision making but used a different paradigm known as the staircase procedure. Participants were asked to make choices between a smaller, immediately obtainable reward and a larger, but delayed reward for three reward amounts: $9, $18 and $36. The value of the smaller reward increased or decreased in incremental steps of 50 while the delay to both rewards was fixed, thereby establishing patterns favoring delayed reward choices when the immediately obtainable rewards were small. Again all rewards were real. Experiment 3 paralleled Experiment 2 except that we had participants make choices between a smaller, sure-thing reward and a larger, but risky reward in order to look at the magnitude effect in probabilistic decision making. We also looked at one additional possible theoretical explanation for the magnitude effect in Experiment 3 known as the peanuts effect. This study is the first to examine the magnitude effect in probabilistic decision making using real rewards. In all three experiments, we found no evidence that any of the possible artifactual explanations of rounding artifacts or a ceiling or floor effect could account for the observed magnitude effects. We also found no evidence that the constant-difference hypothesis or the peanuts effect could explain the magnitude effect. The data suggest that the magnitude effect is indeed a real phenomenon that remains in need of explanation.

The Nuanced Self: A New Accuracy Measure in Interpersonal Perception
Maria Gabriela D. Pereira
This thesis examines three different types of interpersonal perception: self-perception, social perception and metaperception. Self perceptions are peoples’ perceptions of themselves; social perceptions are their perceptions of other people, and metaperceptions are how they think others will perceive them. This research focuses on the links between these three types of perception. Previous research in this area has documented both error and accuracy in these types of perceptions uncovering significant differences between mean ratings for each type of perception alongside strong correlations between the three. In this paper, we argue that mean differences and correlations are not sufficient to assess the accuracy of interpersonal perception. We propose a new additional accuracy measure: the accuracy of variability. This measure does not examine mean differences of ratings themselves, but the standard deviations across ratings. The results of three studies show that there are significant differences between the variability of self and both social and metaperceptions; participants rate themselves as being more “nuanced” than others rate them, and rate themselves as more nuanced than they expect others rate them. Although there is no apparent overall difference in variability for social and metaperceptions, the results in at least one study yield significant interaction between the variability of social and metaperceptions when the relationship between individuals is considered. Participants expect friends to rate them as more nuanced than friends actually do. With strangers, on the other hand, participants expect less nuanced ratings than is actually the case. Throughout this thesis, we argue that a measure of variability across traits is useful for assessing both error and accuracy in interpersonal perception. Discussion focuses on avenues for future research.

The Plot Thickens: Children’s Autobiographies and Parents’ Biographies of Their Children
Amy L. Sprengelmeyer
The present study attempted to address two questions: 1) what are the autobiographies of pre-adolescents and adolescents like? and 2) along what lines do children’s autobiographies converge or diverge with their mothers‚ accounts of the same life? Children of ages 8, 11, and 14 and their mothers, 15 in each age group, participated in this study. The children in the pairs were asked to write their own life story; the mothers were asked to write the life story of their child.

The study shows that as children get older, they are more likely to agree with their parents; however, they are also more likely to disagree on specific pieces of information. As children age, their narratives come to resemble the narratives of adults: they include turning points, elaborate on events, and include more references to emotion. These findings support Bruner’s argument that narrative structure guides autobiographical memory (1993).

Gender differences were also observed. Females wrote more emotionally, made more references to other people, and included more detail in their autobiographies than males did. Males, on the other hand, had a higher convergence with their mothers about mentioning specific events than females did.

Socio-economic status and presence or absence of siblings emerged as mediating factors in the narrative process. The overall tone of the narratives was measured by reader’s response. This analysis showed that mothers and children communicate their lives as being happy overall, even when they mentioned specific negative events.

When the Group Does Less than the Sum of Its Members: Unpacking Effects in Allocations of Responsibility
Wayne M. Wight
Three studies test an extension of support theory and overclaiming research. Participants tend to rate the productivity of a group as greater when the group is broken down (unpacked) into individual members as opposed to when the group is considered (packed) as a whole. This phenomenon occurs whether participants are members of the group that they are evaluating or uninvolved outside observers. When participants are members of the groups that are under evaluation, unpacking the group reduces overclaiming - participants become less likely to self-allocate more responsibility than they are due. Alternative hypotheses based on numerosity and artifactual effects are considered and tested in Study 3.