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Abundance Analysis and Modeling of Five Planetary Nebulae
James A. Bates
The spectra of five planetary nebulae (PNe), J900, NGC 3242, NGC 2242, NGC 40, and IC 418, were reduced and analyzed to determine abundances of helium, oxygen, carbon, nitrogen, neon, and sulfur. These abundances, made with a five level electron balancing program, were used as inputs for a modeling program. This approach takes the limited data from a spectrum and interprets them with the help of a full photoionization model.

This work is a part of a project to study the abundances of 75 planetary nebulae. The information in this homogeneous database can be used to compare nucleosynthesis theories with observations, and can also be used to assess the role PNe play in the chemical evolution of the galaxy.

High-Frequency Waves in the Solar Corona at the 1998 Total Eclipse Implications for the Coronal Heating Problem
Timothy H. McConnochie
We observed the total eclipse of February 26, 1998, from the vicinity of Nord, Aruba, in order to search for evidence of high-frequency waves in the solar corona. Images of the coronal green line and of a reference spectral region in the coronal continuum were acquired at a rate of 10 frames per second. Our Princeton Instruments CCD camera was used in frame-transfer mode and was mounted on a 36 cm Celestron Schmidt-Cassegrain telescope. Several theories of coronal heating rely on high-frequency magnetohydrodynamic waves to transfer the necessary energy. We hope to constrain theories of coronal heating by either detecting or ruling out the presence of coronal oscillations produced by these waves. Preliminary analysis of the 1998 data indicates that we should be able to either rule out or detect coronal oscillations with normalized amplitudes greater than 1.5%. No oscillations with amplitudes this large have yet been identified, although coronal oscillations with normalized amplitudes of 0.8% do seem to be present in two different locations. The frequencies of these apparent oscillations are 3.77 and 4.82 hertz respectively, but more rigorous statistical analyses are required to determine if detections with amplitudes this far below our conservative estimate of 1.5% can be considered real.


Inositolphosphorylceramide Synthesis in Plants: Characterization of a Novel Enzyme Involved in Plant Sphingolipid Metabolism
Pamela E. Bromley
Iinositolphosphorylceramides (IPC) are a class of sphingolipids present in plants, fungi, and protozoa. The activity of IPX synthase, the enzyme catalyzing the first step in the synthesis of complex inositolphosphorylceramides, has been characterized in a plant system. This work represents the first detailed characterization of the enzyme in any system, plant or fungal. IPC synthase catalyses the following reaction:

phosphatidylinositol + ceramide -> inositolphosphorylceramide + diacylglycerol

Enzyme activity in a microsomal membrane faction from bean hypocotyls was assayed by monitoring the incorporation of [3H]IPC and/or fluorescent IPC. The apparent Km for PI was approximately 43 µM. The enzyme exhibited a relatively strong preference for ceramides with d18:1 long chain bases and C18 and C24 non-hydroxy fatty acids, with optimal activity at a substrate concentration of 0.27 nM. The pH optimum was 7.8, and the temperature optimum was 27.5ûC. Previously, IPC had only been reported in a few important agricultural plants. Significantly, enzyme activity was observed in a variety of different plants and tissues, lending support to the notion that IPC are widespread if not ubiquitous in plants. A known inhibitor of IPC synthase in fungi, aureobasidin A (AbA), was found to be a potent inhibitor of IPC synthase in plants, with 50% inhibition at just 0.8 nM, indicating that AbA is a potential broad spectrum fungicide and herbicide.

Genetic, Molecular, and Cellular Studies of the CDC14 Pathway in Saccharomyces cerevisiae
Meghan Byrne
CDC14 is an essential gene in the budding yeast, Saccharomyces cerevisiae. This gene encodes a 62kD protein containing the active site motif and in vitro activity of a dual-specificity phosphatase (Taylor et al.. 1997). Mutations of CDC14 are temperature sensitive, causing the cell cycle to arrest at late anaphase/early telophase at the restrictive temperature (34-37ûC). What proteins Cdc14p interacts with and how the CDC14 pathway controls exit from mitosis are unknown. In this study, three lines of inquiry were pursued to elucidate the CDC14 pathway. First, suppressor analysis was performed to identify genes encoding proteins that suppress the temperature sensitivity of cdc14 mutants and that potentially interact with Cdc14p. Suppressor analysis was performed using cdc14--1 and cdc14-2 mutants, and both dominant and recessive suppressors were analyzed. Secondly, a plasmid was created to clone the cdc14 mutant alleles for characterization and nucleotide sequencing. The plasmid was created from the pJWc100 plasmid, which has a pRS316 backbone and a CDC14 insert, using site-directed mutagenesis to incorporate unique restriction sites at both ends of the CDC14 open reading frame. These restriction sites will allow the open reading frame to be excised and the mutant alleles to be rescued via gap repair. Thirdly, bud-scar patterns in cdc14, sfp1-1, and sfp1-2 mutants were analyzed. The sfp1 mutations were first isolated as suppressors of cdc14's temperature-sensitivity phenotype (Schilling 1995). The bud-scar pattern analysis revealed that, compared to wild-type bud-scar patterns, cdc14 mutants grown at 25ûC exhibit normal patterns, whereas sfp1-1 and sfp1-2 mutants exhibit a high frequency of abnormal patterns of bud-site selection.

Methods to Uncover the Transmission of Birdsong in a Population of House Finches, Carpodacus mexicanus
Matthew A. Garland
Birdsong, as a learned trait, is analogous to human speech, and because of its similarities has been well studied in the past. However, it has been difficult to separate the environmental component of learned song from any genetic component. A set of methods, which will enable better understanding of the differences in the biological transfer of birdsong, were devised and refined. These methods, performed on the house finch, Carpodacus mexicanus, and the zebra finch, taeniopygia guttata, have been divided into three distinct steps: capturing and extracting blood from birds, extracting DNA from bird blood, and performing RAPD-PCR (randomly amplified polymorphic DNA-polymerase chain reaction), using the extracted genomic DNA as a template. The goal of the methods is to use RAPD-PCR polymorphism data to construct a tree diagramming the relatedness of the local populations of house finches; once this is accomplished, changes in song characteristics can be mapped through the population, hopefully shedding light on how and why birdsong changes in a population, and how song is related to genetic factors.

Creation of an Antibody to and Characterization of the AAR1 Protein in Arabidopsis thaliana
Mary A. Gehring
Lateral root formation is known to be induced by the plant hormone auxin. It is unknown, however, how auxin leads to this morphological change. Previously, it was determined that an Arabidopsis thaliana gene Arabidopsis Auxin Regulated 1 (AAR1) was expressed in root tissue after auxin induction. In this project, an antibody was made against the protein encoded by the early auxin response gene. The antibody was used to detect AAR1 on Western Blots of wild type Arabidopsis thaliana (Columbia ecotype) shoots and roots and in transgenic arabidopsis plants which constitutively express the AAR1 gene. It was expected that auxin application would cause an AAR1 protein increase in wild type plants. Protein increase after auxin treatment was never detected in shoots or roots, though higher levels of mRNA in transgenic plants produced correspondingly higher AAR1 protein levels. It was also shown that AAR1 was generally more abundant in wild type roots than shoots.

Characterization of Transgenic Plants that Overexpress AAR1
Arminda L. Gensler
Plants synthesize hormones that travel throughout the organism and act as signaling molecules to cue developmental processes. However, little definite is known about the exact mechanisms of the plant hormone auxins action and auxin signal transduction. This thesis attempts to further characterize the functional role of the novel primary auxin response gene AAR1 in Arabidopsis thaliana. Transgenic strains containing the AAR1 cDNA insert behind the constitutive 35S CaMV5 promotor show increased accumulation of AAR1 mRNA relative to wt. These strains can be ranked as followings according to relative increases in mRNA accumulation: wt, C1K4, B1C2, C1C3, C1B6, B1B1. Transgenic plants that overexpress AAR1 mRNA and protein do not appear to have a phenotype different from wt. This suggests that the AAR1 gene product, by itself, does not play a critical role in plant development. Transgenic plants that possess increased levels of AAR1 mRNA and protein do not have increased accumulation of RPñ16 mRNA. RPL16 is a secondary auxin response gene. This lack of induction suggests that AAR1, alone, does not play a regulatory role in the auxin signal transduction pathway for RPL16. The level of AAR1 mRNA accumulation in wt plants responds to stimuli other than auxin. Heat shock causes a dramatic reduction in AAR1 mRNA accumulation; cadmium chloride addition results in a moderate reduction of AAR1 mRNA accumulation. A complete sequencing of the AAR1 gene, including its promotor region, would allow us to understand how it is regulated; thus, we could potentially gain further insight into the function of this gene.

Early-Induced Puberty: Effects on Song Leaning in the Zebra Finch
Deborah A. Hirschmann
Unlike many other bird species, male zebra finches are close-ended learners. Males acquire their song in chunks from one or more song tutors (Williams & Staples, 1992), eventually fixing syllables in a permanent order which they will sing in a stereotyped manner for the rest of their lives. This song crystallization, occurring between 70 and 90 days of age, marks the close of the critical period for song acquisition (Immelman, 1969). Many lines of evidence suggest a role for testosterone (T) in song crystallization. For example, the first major testosterone surge in zebra finch males occurs around day 75, marking the onset of both puberty and song stereotype (Prove, 1983). Furthermore, castrated zebra finches add syllables to their songs well after song acquisition is purportedly complete (Arnold, 1975), and males treated with testosterone early in life produce prematurely crystallized songs (Korsia & Bottjer, 1991). It thus appears that high plasma testosterone levels may close sensitive periods for learning. This study explored, through the administration of testosterone implants at 60 days, whether prematurely inducing puberty in male zebra finches limits their critical period for song acquisition. It also attempted to further elucidate, through the joint administration of testosterone and the T-antagonist flutamide, the specific pathways by which testosterone influences song learning and neural plasticity. The songs of treated birds differed from those of controls in several respects. Birds treated with testosterone and flutamide (TF) exhibited more changes in their song than did finches in the T-only or control groups. When compared to controls, T-treated birds also appeared to alter their syllables earlier and TF birds later in song development. Intriguingly, birds added call-like and complex syllable types in the same proportions as found in their original songs. Control birds appeared to stabilize the identify of dominant song types around 90 days, while those of treated birds remained more variable. Finally, TF birds tended to copy a lower proportion of syllables from their tutors than did either T or control birds. In conclusion, the present study suggests that while the administration of exogenous testosterone at 60 days may induce early crystallization of song in male zebra finches, decreasing the effects of androgenic exposure, through the joint administration of testosterone and the anti-androgen flutamide, appears to enhance neural plasticity and prolong critical periods for learning.

The Effect of Dispersal Mechanism on the Recolonization of Spring Ephemeral Species from Primary to Secondary Woodlots
Jody Knight
The history of Williamstown is one of fluctuations in the extent of forest cover. Large chunks of forest were at one time cleared for use as farmland and then allowed to regrow. This clearing of the land has had a lasting impact on the forest flora, especially the herbaceous layer, which takes much longer to return to forests than do tree species. Spring ephemeral species, a major component of the herbaceous layer, are hypothesized to work as a springtime "vernal dam," holding in the system nutrients that might otherwise be lost due to leaching. The dispersal mechanisms of spring ephemerals affects the way that these species recolonize secondary forest (forest that has been cleared and then allowed to regrow) from primary forest (forest that has never been cleared). Wind and vertebrate dispersed species disperse at a higher rate than do ant dispersed species. Ant dispersed species, on the other hand, once established tend to form a more regular cover than do wind and vertebrate dispersed species. Other factors, such as canopy composition, topography, and soil conditions, also appear to affect the recolonization by spring ephemerals.

Genetic Variation for Plasticity in a Natural Population of the Chorus Frog (Pseudacris triseriata)
Carolyn McBride
Examining the potential for natural selection on phenotypic plasticity is crucial to the study of evolution in heterogeneous environments. It is therefore important to measure the heritability of plastic responses within natural populations. Along the rocky shore of North Government Island, Isle Royale National Park, MI, the chorus frog (Pseudacris triseriata) breeds in small temporary pools. Pseudacris tadpoles developing in pools with their main predator, the dragonfly nymph (Aeshna juncea), develop larger tail fins than tadpoles developing in pools without dragonflies. In this study, I tested for broad-sense heritability in this plastic response by carrying out an experiment employing a split brood full-sib design. I partitioned full-sibling tadpole families (sibships) among natural pools containing either caged dragonflies (unable to kill experimental tadpoles) or empty cages. By using RAPD-PCR based molecular markers to assign experimental tadpoles to known sibships at the end of the experiment, I was able to begin the predator and non-predator treatments as soon as the tadpoles hatched, rather than waiting until they developed unique tail spot pigmentation patterns by which to identify them. I monitored the morphology of experimental tadpoles over the course of 25 days and described the plastic response of each sibship as the set of phenotypes its members produced across the two environments (reaction norm). I detected significant variability among sibships in the mean (and possibly slope) of reaction norms for tail shape indicating broad-sense heritability and a continued potential for the evolution of tail phenotypes within this population.

Breeding System and Small-Scale Population Genetic Structure of Sagina Nodosa (Caryophyllaceae), Isle Royale, Michigan
Benjamin R. Montgomery
Loss of genetic diversity and resulting inbreeding depression may affect the success of rare plant populations. At the northeast tip of Isle Royale, Michigan, a community of rare arctic plants has persisted for the last 10,000 years, and the populations may be small enough to experience a substantial degree of inbreeding depression. We investigate the partitioning of genetic diversity among one island population of Sagina nodosa, an arctic-disjunct plant. We use the technique of RAPD-PCR to detect genetic diversity among individual plants from North Government Island, and we use several statistical tests, including analysis of molecular variance (AMOVA) to determine whether diversity if non-randomly distributed throughout the population. Our results indicate that the population is highly structured among the sub-populations (p<0.01), and among cracks in rocks within the sub-populations examined (p<0.1). Furthermore, linear distance among sub-populations is not correlated to genetic variation among sub-populations, which suggests that when gene flow does occur between sub-populations, it may bypass intermediate sub-populations. Finally, we determine that S. nodosa is fully self-compatible, which indicates that sub-populations may be founded by as little as one individual plant. Overall, these results suggest that a substantial amount of genetic variation occurs between sub-populations of S. nodosa, suggesting that conservation efforts should emphasize the maintenance of all sub-populations rather than only the most successful ones.

Language and Brain: Effects of Arterial Occlusion (Stroke) on Human Brain Morphometry and Specific Language Abilities
Nedim T. Sahin
Language task localization in the human brain was investigated using a lesion-study approach. MRI-based volumetric lesion quantification and subsequent mapping in 21 adult stroke patients revealed three patterns indicative of Middle Cerebral Artery perfusion fields. Psycholinguistic aphasiological examination revealed that language deficits could be broken down into discreet subunits, according to hierarchical models of language processing. Correlational analysis showed that lesions in chosen anatomic areas accounted for much variance in some language scores, tentatively ratifying localizationist models; and further indicated a region in the inferior temporal lobe to be strongly predictive of deficits on many tasks. This study would be a fitting pilot for future research (including functional studies) and the results are tentative. Nonetheless, the results suggest that core language functions may be subserved by regions external to the classic perisylvian language areas. The study was carried out at Massachusetts General Hospital under the supervision of Dr. Verne S. Caviness, Jr., who performed the original morphometric analysis, and Dr. David N. Caplan, who performed the linguistic assessment. My role has been to map the lesions, assess lesion patterns (Sahin, et al., 1998), and perform correlational analyses to assess specific language task localization.

Population Structure and Gene Flow in Chorus Frog Tadpoles (Pseudacris triseriata) on North Government Island, Isle Royale National Park
Joshua A. Shapiro
This study examines the interactions f gene flow and selection in structuring a population of chorus frog tadpoles (Pseudacris triseriata) on North Government Island, Isle Royale National Park. The island was mapped and characterized in detail, with particular reference to the interactions between the tadpoles and their main predator, dragonfly nymphs. Tadpoles from different regions of the island were raised in a natural environment to discern genetic differences in morphology and RAPD-PCR was used to analyze differences in neutral genetic markers among tadpoles. Tadpoles from the northeast end of the island tended to have larger tailfins relative to their body size, which corresponded to the fact that there was a greater amount of interaction between the tadpoles and dragonfly nymphs at that end of the island. There was not, however, any significant differentiation in the RAPD markers between the tadpoles at the northeast end of the island and those at the southwest end. There was a positive correlation between the physical distance between the pools from which tadpoles originate and the genetic distance between the tadpoles from those pools, but only at a small scale (<50m).

These data suggest that the level of gene flow in the population of tadpoles on North Government Island is somewhat restricted, likely by the fact that adult frogs return to the region near the pool in which they metamorphosed to mate. This restriction in gene flow is not enough to cause large scale differentiation between the ends of the island, as evidenced by the RAPD data, but it is sufficient to create a gradient in the expression of genes such as tailfin height, which are targets of selection.

Elucidating the Genetic Mechanisms of Muscle Fiber-Type Diversity: An In Vivo Transcriptional Analysis of the Myosin Heavy Chain Type IIB Promoter
Emily C. Snyder
The aim of this project was to identify and characterize the fast muscle fiber-type specific element(s) of the myosin heavy chain type IIB (IIB-MyHC expression. Numerous deletion constructs that targeted evolutionarily conserved motifs were generated in the context of the proximal 300 bp. In vivo activity of each promoter deletion construct was determined in the fast-twitch tibialis anterior (TA) muscle and the slow twitch soleus muscle of the rat hindlimb by the technique of somatic gene transfer. Transcriptional activity of each construct in myotube culture was also determined in a cell culture transfection study. Deletion of the two distal AT-rich regions, mAT3 and mAT2, resulted in a marked decrease of activity in the soleus and TA, suggesting that these elements are required for high levels of activity of the promoter. Deletion of these two elements distal AT-rich regions caused a parallel decrease of activity in myotube culture. The mAT3 region seems to be involved in non-fiber-type specific regulation of the promoter. However, because deletion of the mAT2 region caused changes in the ratio of soleus:TA expression, this element may have a partial role in conferring fast-twitch fiber specificity to the IIB-MyHC promoter. Deletion of a third proximal AT-rich region, AT1, resulted in a significant increase in activity in both the TA and the soleus muscles, indicating that it is a non-fiber-type specific transcriptional repressor of the IIB-MyHC gene. Deletion of this element had little effect on transcriptional activity in myotube culture, suggesting that the repressive effect of this element seems to be restricted to the context of intact adult muscle. Deletion of the CArG region resulted in a moderate increase of activity in both the soleus and TA muscles, and a significant decrease of activity in myotube culture. Mutation of 10 bp upstream of this element caused a similar effect on in vivo expression. This region may be involved in conferring adult muscle cell specificity to the IIB-MyHC gene. The proximal 85 bp of the IIB-MyHC promoter containing an E-box and the TATA box was determined to be insufficient to confer a significant level of activity to the promoter in either the Ta or the soleus or in myotube culture. In sum, while the fast-fiber specific element of the IIB-MyHC promoter was not identified in this project, much was elucidated on the roles of several evolutionarily conserved elements in transcriptional regulation of the IIB-MyHC promoter.

A Regulatory Role for MyoD in the Expression of Myosin Heavy Chain IIB
Matthew Wheeler
The myogenic transcription factor MyoD has previously been shown to accumulate in adult fast-twitch muscle. However, whether MyoD plays an active role in the generation of fiber-type, or is simply a result of fiber-type remains to be determined. Hindlimb suspension (HS), a model that induces slow to fast muscle conversion through unweighting, as utilized to determine the physiological pattern of expression of MyoD and the fast myosin heavy chain type IIB (IIBMyHC). Soleus muscles, which do not normally express either MyoD or IIBMyHC, expressed both MyoD and IIBMyHC RNA after only one week of HS. In vivo injection of promoter-reporter vectors was used to further characterize the relationship between MyoD and IIBMyHC. The proximal 300 bp or the IIBMyHC promoter contains at least one element required for muscle fiber-type specific expression. Within this 300 bp region lies an E-box, a putative binding site for MyoD. MyoD is shown to form a specific interaction with this particular E-box. When 4 bp of this E-box is mutated, binding of MyoD is eliminated. When this mutation is placed within the context of the IIB promoter-reporter construct, MyoD induction of reporter gene expression in co-transfected C2C12 cells is reduced 30-fold. This mutation also decreases activity 67-fold as compared to the wild type promoter within the fast twitch tibialis anterior muscle following in vivo injection. Heterologous reporter constructs demonstrate an ability of the E-box to activate transcription in fast muscle, while elimination of the E-box prevents this activation from occurring. These data suggest that MyoD can regulate the expression of the IIBMyHC gene, and indicate a probable causative role for MyoD in the observed upregulation of IIBMyHC in HS soleus.

Genetic Investigations of cdc14 Suppressors and Directed Two-Hybrid Analysis of CDC14 and SFP1
Kyra C. Williams
Cell division cycle (CDC) proteins are essential for progression of the cell cycle in Saccharomyces cerevisiae (budding yeast). Each CDC protein acts at a distinct point in the cell cycle such that cdc mutants arrest growth with a uniform cellular morphology. CDC-mutants are temperature-sensitive, allowing the cells to continue growing at the permissive temperature of 25ûC, but inhibiting growth at the restrictive temperature of 34ûC (Hartwell et al., 1974). This characteristic allows genetic studies to be performed on the cells that, at normal temperatures, constrain functional proteins, but still enable the detection of cell-cycle arrest at the restrictive temperature. CDC14 is a cdc gene whose activity is not well understood. Although it is known that CDC14 is required for progression through late anaphase/early telophase, the mechanism whereby it allows exit from mitosis is not known. CDC14 encodes a dual-specificity protein phosphatase (Taylor, et al., 1970.)

To further understand the function of CDC14, suppression analysis was used to identify other proteins involved in the CDC14 pathway. Numerous recessive cold-sensitive suppressors of cdc14 were identified. One of these suppressors was found to contain a partially dominant suppressing mutation in SFP1.

Split finger protein 1 (SFP1) has already been found to be capable of suppressing the CDC14 mutation (Sagasti 1996, Shaw 1996, Paliulis 1997). The mechanism of interaction between SFP1 and CDC14 is unknown. An sfp1 null mutation is incapable of suppressing the temperature-dependent lethality of a cdc14-disruption mutation, indicating that sfp1 does not completely bypass the activity of CDC14 (Paliulis 1997). It is possible that SFP1 suppresses cdc14 by restoring pseudo-wild type interaction.

Two-hybrid analysis can be used to test whether interaction between SFP1 and CDC14 occurs. In this system, the gene for one of the proteins thought to be interacting is fused with the transcription activation domain of either GAL4 or LexA. The gene for the other protein is fused with the DNA binding domain that can bind upstream of a reporter gene. When the transcription activation domain and the DNA binding domain are localized together through the interaction of the two exogenous proteins, a phenotypic signal is produced from the reporter gene (Fields and Song, 1988). The SFP1 gene was subcloned into a plasmid containing an f1 origin of replication in order to use site-directed mutagenesis to create restriction sites flanking the gene. These sites can then be used to subclone the gene into a two-hybrid vector to determine if interaction with CEDC14 occurs.

Larval Foraging Behavior of the White Cabbage Butterfly Pieris rapae (Lepidoptera: Pieridae)
Robert Wittenmyer
The larval foraging behavior of the crucifer-feeding specialist Pieris rapae, the European white cabbage butterfly (Lepidoptera: Pieridae), and the subsequent pattern of damage inflicted upon its host plants were investigated. Larvae were observed on the cultivated hosts broccoli (Brassica oleracea) and radish (Raphanus sativus), and on the wild hosts Brassica nigra and Hesperis matronalis. Observations of position and behavior were made throughout the larval life span of P. rapae caterpillars, and the damaged leaves were digitally stored and analyzed. As larvae aged, they were found to spend significantly less time feeding and moving on B. oleracea, B. nigra, and H. matronalis. In general, young larvae spent considerably more time on the undersides of leaves, and their positional preference reversed with caterpillar age: older larvae spent significantly more time in direct sunlight. Damage was shown to be significantly aggregated on one or a few leaves within 23 of 32 host plant replicates. Although a majority of the 318 leaves examined had zero or less than 5% of their area consumed, statistical analysis found that damage was very significantly concentrated within individual leaves.

Genetic Variation in Arctic Disjunct Subpopulations of Saxifraga tricuspidata (Saxifragaceae)
William N. Woodfield
We examined the genetic variation between different island subpopulations of the arctic disjunct population of Saxifraga tricuspidata on the northeastern islands of Isle Royale, Michigan. We mapped an entire S. tricuspidata subpopulation at the southeastern end of Edwards Island, studied the pollination behavior of S. tricuspidata using manual pollination experiments, and examined molecular genetic partitioning between 4 different island subpopulations, using randomly amplified polymorphic DNA (RAPD) analysis. By analyzing the proportion of ovules that set seed in experimentally manipulated flowers, we discovered that S. tricuspidata is self-compatible and that the proportion of seeds set varies according to the identity of the pollen donor. We used 3 primers on 71 individuals in the RAPD-PCR analysis and scored 15 polymorphic loci. A calculation of Shannon's information measure estimated 95.8% of genetic diversity results from within-population diversity with only 4.2% resulting from among-population diversity. A calculation of Wright's Fst estimated a value of 0.106, indicating a low degree of structuring between subpopulations. AMOVA revealed an estimate of 96.65% genetic variation within subpopulations and 3.35% variation between subpopulations, and a [Phi]st, an analog of Fst, of 0.033. A principal component analysis and the construction of a phylogram confirmed the lack of subpopulation differentiation. We also estimated the number of individuals migrating between subpopulations as 7.33 per generation. The results of this thesis indicate a strong mechanism of gene flow between island subpopulations, a mechanism that is important in maintaining genetic diversity within the population as a whole.


Mutagenesis of the Interleukin-4 Promoter
Robert Chang
The expression of Interleukin-4 in mast cells is under the control of several regulatory elements within the promoter region. A negative regulatory element named NEG-1 has been isolated using both in vivo and in vitro methods. Loss of the NEG-1 element in the in vivo reporter gene constructs resulted in an increase in gene transcription, while in vitro electrophoretic mobility shift analyses demonstrated that specific nuclear factors bound to the NEG-1 region. To further understand Interleukin-4 expression in mast cells, mutations of four to six base pairs were introduced into the NEG-1 region by taking advantage of the M13 bacteriophage life cycle. The promoter region of IL-4 from -442 to +5 had already been inserted into the M13 cloning site. The mutations were introduced by incubating the single-stranded form of the vector with oligonucleotides containing the mutations. DNA replication was allowed to occur followed by the selective digestion of the wild-type strand. The strand of DNA containing the mutations was then used as a template for a final round of DNA replication. The mutated promoter was excised from the M13 double-stranded form and inserted into a pCAT-Basic promoter, eventually for use in reporter gene assays to determine the temporal nature of Interleukin-4 expression.

Elucidation of the Mechanism by which RecA* Mediates the Autodigestion of LexA in Bacillus subtilis
Jessica A. Charland
LexA is the 23 kDa autocatalytic repressor of the Bacillus subtilis SOS regulatory repair system, a network of 20 unlinked damage inducible (din) genes. The RecA protein, activated by binding ssDNA and dNTP to form activated RecA (RecA*), mediates the autocleavage of LexA, which then derepresses the SOS system. Based on computer modeling studies, we propose that RecA binds LexA, forcing Arg166 to fold into the active site, facilitating general base catalysis of the active Lys165 residue. The work presented here supports our model of how LexA autodigests in the presence of RecA*. This study involves using site-directed mutagenesis to evaluate the role of Arg166 in the catalysis reaction. In addition, cysteine residues were substituted at LexA positions 101 and 148 using site-directed mutagenesis in preparation for cross-linking experiments with RecA. Residues 101 and 148 are thought to be on the RecA*-LexA binding surface. Assays were either performed in the presence of RecA to simulate in vivo cellular conditions. Results suggest that Arg166 is, in fact, important to the cleavage reaction. The pH profile for wild type LexA suggested a pKa of around 6. This value was shifted to about 6.7 for mutant RQ166. This shift indicates that this residue is involved in catalysis.

The Oxidation of Benzyl Ethers via Phase-Transfer Catalysis
Bo Yoon Choi
A useful method for oxidizing benzyl ethers to benzoate esters using potassium permanganate under conditions of phase-transfer catalysis was investigated. The study encompassed a wide range of structural systems, ranging from simple aliphatic benzyl ethers to complex cyclic ethers. Yields were good to excellent. The primary site of oxidation was benzylic and adjacent to the oxygen atom of the ether. It is believed that this double activation offers stability to a carbocation intermediate. A competitive oxidation study between dibenzyl ether and tribenzylamine revealed that the oxidation of tribenzylamine proceeded faster than that of dibenzyl ether by about 150 times.

Hetero Diels-Alder Routes to Beta-Carboline Alkaloids
Matthew L. Crawley
A concise route to yohimban, a [beta]-carboline alkaloid, was started in a five-step convergent synthesis. 14-Carboxy-15,20-didehydroyohimban-21-one (27), a direct precursor to the desired product, was synthesized in three steps. The key step was an intramolecular annulation of 3,4-dihydro-[beta]-carboline with tetrahydrohomophthalic anhydride, which had the net effect of a Diels-Alder addition. The preliminary attempts to decarboxylate (27) to 15,20-didehydroyohimban-21-one (28) were unsuccessful. Other efforts to synthesis hexadehydroyohimban and berbine through annulation like reactions with other dienes were unsuccessful.

Synthesis of Organic Electrochromic Materials based on Benzoquinone Centers and Attempted Synthesis of an Anthraquinone Ligand for a Ruthenium-Polypyridine Complex
Matthew D. Kelty
The quenching of the fluorescence transition A 2[Sigma]+, v = 0 -> X2[Pi], v' = 3 of nitric oxide (NO) in the presence of halogenated methanes and ethanes was observed. Measurements were taken on chlorinated methanes (CCl4, CCl3H, CCl2H2, and CClH3), fluorocarbons (CF4, CF3H, CF2H2, CFH3, and C2F5H and C2F6), and bromofluoromethanes (CBr2F2 and CBrF3) over a range of temperatures from 220 to 295 K. The rate constant of the fluorescence decay curve is measured at several different pressures to give a dependence of the decay constant on the partial pressure of the quencher. From this we can determine the quenching efficiency, reported as a cross section, of the species being tested. The temperature at which these measurements are made was also varied, giving a temperature dependence of the quenching cross sections.

None of the species tested had electronic energy levels close to the energy of excited state NO. For this reason there was negligible contribution to quenching due to near-resonant electronic energy transfer. The fluorocarbons displayed poor quenching efficiency, due to their highly endothermic electron affinities. The chloromethanes and bromofluoromethanes displayed strong quenching ability, due to their favorable electron affinities.

The observed quenching behavior was analyzed via both the harpoon and collision complex models to evaluate the validity of each. The temperature dependent behavior is best interpreted as the well-depth calculated with the collision-complex model. Quenching ability, however, is ultimately determined by the electron affinity of the quencher. This electron affinity affects the position of the ion-pair potential energy surface, and therefore the position of the ionic/covalent curve crossing. It was also found that electron affinities that are calculated from quenching experiments show an incorrect temperature dependence, which is due to the assumptions inherent in the simpler energy transfer models.

Further Study of the Cooperativity of Two Negative Regulatory Elements of the Murine IL-4 Promoter
Allison C. Lamanna
The production of Interleukin-4 (IL-4) is highly restricted to mast cells and certain T cell subsets; previous data indicates that the levels of IL-4 produced are under strict transcriptional control. Studies have demonstrated that there are several DNA regulatory elements within the 5' flanking region of this gene and that specific nuclear factors interact with these sequences. In concert, these various interactions regulate the inducible transcription of IL-4. We have defined a DNA element designated NEG-1, (-326 to -302 relative to the transcription initiation start site) that contributes to the down regulation of this gene in murine mast cells. Our data indicates that this element is the site of specific nuclear protein(s) binding events in vitro. By mutational analysis in transient transfection experiments we have defined two subsequences (A and B) required for the normal functioning of this negative regulatory element in vivo. Electrophoretic mobility shift analyses were used to explore the possible interactions of nuclear factors binding to these two sites. The data to date suggests that, initially, protein factors bind to the A site and subsequent factors recognize this complex and bind in a cooperative manner. For complete functional activity of the Interleukin-4 NEG-1 element, both binding events must occur. Cross-linking experiments indicate that the factor which binds initially to the A site is approximately 74.6 kD.

Laboratory Studies of SO2 Adsorption on Soot From -130ûC to -30ûC
Victoria T. Nicholson
Recently the exhaust from airplanes has been of much interest. It has been shown that oxidation of SO2 to H2SO4 occurs much more rapidly in airplane exhaust than what is predicted by any known mechanism. Using this as motivation, we are interested in studying the interactions between soot and SO2 because we believe that soot may be a catalyst for the SO2 oxidation process. We have performed our experiments under the conditions that are seen by the airplanes when they are flying near the tropopause. Our experiments have been performed in the temperature range of -130ûC to -30ûC. The SO2 pressures allowed to interact with the soot range from 10-5 torr to 10-3 torr. Our primary detection tools are a FTIR and a mass spectrometer. They both help to map the SO2/soot interactions. The results of our experiments have proven the original hypothesis that SO2 sticks more readily at high pressures and low temperatures. Furthermore we have been able to quantify our data using the oscillation pattern of the baseline. From our data we have found that [theta]sat, one saturated layer of SO2, is equal to a net coverage of 8ML. Taking into account the roughness of the soot, the local coverage of SO2 at [theta]sat is ³ 0.07ML per soot surface, but most likely equal to 0.15ML per soot surface. We have also observed that at relatively high pressures and temperatures, the "normal" peaks that we see for SO2 gradually broaden and change to become triplet peaks. At this point we are not certain what has caused the change in the spectra, but because the peaks have been blue-shifted we know that something is strongly interacting with the SO2 which is causing the oxidation number of the sulfur to increase.

Synthesis and Characterization of Liquid Crystalline Copper(II) Metal Chain Complexes
James M. Rowe
This work focuses on the synthesis and characterization of novel families of metallomesogens based on metal-chain complexes that show promise as one-dimensional magnetic materials. Liquid crystalline properties have been introduced into the family of trans-Cu(pyr)2X2 materials by derivatization of the pyridyl ligands, and bipyridyl ligands derivatized with both esters (4,4'; 5,5'; 3,3',5,5'; 4,4',5,5'; and 4,4',6,6') and dialkylamides (4,4' and 5,5') have been synthesized in order to make mesogens based on Cu(bipy)X2 systems. When the aliphatic portion of the mesogen in Cu(pyr)2X2 is introduced via an ester, no mesophases result. However, when an amide group is used, mesogenic material results. The structure of the amide-derivatized material is different from solution than from the melt, due to changes in hydrogen-bonding framework, and only the latter exhibits mesophases. Further, the inclusion of hydrogen-bonding groups at positions opposite the metal-coordination sight significantly affects the environment of the metal, presumably via compression of the bridging Cu-X bonds. To this point neither ester (5,5' and 4,4',6,6') nor dialkylamide (5,5') functionalites have been able to induce mesophase behavior on the Cu(bipy)X2 system, however the synthesis of promising tetraesters (3,3',5,5' and 4,4',5,5') is near completion.

Turing Patterns in a Templator Mechanism
Leo L. Tsai
We observe the formation of Turing patterns in the minimal Templator Model, developed in 1996 by Peacock-L--pez, Radov, and Flesner. Predictions from stability analysis performed on the model have led to observations of stable spot, striped, honeycomb, and labyrinth patterns via computer simulations employing the cellular automata method.


Generalized Forcing in Aperiodic Tilings
Linden Minnick
Aperiodic patterns occur in many dimensions. Properties of certain one-dimensional aperiodic sequences, known as musical sequences, are extremely helpful in understanding similar properties in aperiodic tilings of higher dimensions. We will use both algebraic and geometric/graphical methods to prove certain properties about forcing patterns of musical sequences. These properties may then be applied to our understanding of forcing patterns in aperiodic tilings of higher dimension, in particular the two-dimensional Penrose tilings. Properties of tiles forced by arbitrary initial patches of tiles may also be inferred in conjunction with other properties of the tilings. In this talk, we discuss many new extensions to previous results.

INDiGENT: Genetically Refining Expert Neural Networks
Brendan D. Burns
Classification systems are algorithms which have the task of separating a data set into a number of separate categories. Given a set of rules which classify a problem, INDiGENT utilizes a genetic search to revise these rules and produce more accurate results. INDiGENT performs two separate searches. One which modifies the set of input features available to the learning system and another which modifies the expert's actual theory. INDiGENT is able to both improve the accuracy of classification and simplify theory construction when compared to a number of other systems.

Exploring the Danzer Tiling
Benjamin C. Chaffin
The Danzer tiling is an aperiodic tiling of space composed of eight tetrahedra. Though it has no translational symmetry, it exhibits long-range icosahedral symmetry, a structure impossible for normal crystals. We will discuss some of the properties Danzer tiling, including vertex configurations (groups of tiles clustered about and sharing a central vertex) and the distances between identical regions of a tiling.

Rupiah: An Extension to Java Supporting Match-Bounded Parametric Polymorphism, This Type, and Exact Typing
Jonathan L. Burstein
The programming language Java has gained widespread acceptance throughout the computer industry. Java's type system, though, is lacking in flexibility. This lack of flexibility limits the expressiveness of the language, especially for the creation of container classes. To improve Java's expressiveness, we extend its type system through the addition of three constructs: match-bounded parametric polymorphism, This Type, and exact typing. These constructs allow a programmer to write flexible, extensible, and statically type-safe code. Our current implementation targets the standard Java Virtual Machine through a source-level translation. Translation allows Rupiah programs to be run on existing Java installations, but carries with it a performance cost.


Evolution of a Late Pliocene Lava-Dammed Lake and Pleistocene Landslides, Espa-ola Basin, New Mexico
Andrew D. Fagenholz
Deposits of clay and coarser sediment in the western Espa-ola Basin, north-central New Mexico, record late Pliocene impoundment and evolution of Culebra Lake. I mapped exposures in canyon walls and along mesa edges between Los Alamos Canyon and north of Garcia Canyon in the Puye and White Rock Quadrangles. In order to reconstruct facies associations and their evolution, I measured stratigraphic sections and described sediment texture, structure, thickness, and composition. I also mapped massive slumps of Bandelier Tuff and recorded orientations of individual blocks. In the laboratory I measured grain size on selected clay samples and recorded composition of volcanic material.

Paleotopographic reconstruction from elevations and isopach maps indicates that Culebra Lake inundated a semi-rugged late Pliocene landscape that was probably a result of semi-arid geomorphic processes. Lacustrine deposits are thickest in depressions in this landscape, where they overlie alluvial fan deposits of the Puye formation. Field mapping demonstrates that the presently dissected toe and midslope of the Puye fan are covered by subaerial and lacustrine deposits up to 30 m thick over >50 km2 in the study area. Basal silt and fine sand probably accumulated when Culebra Lake was smaller than its maximum size of ~1,000 km2. Widespread, massive, illite/smectite- and kaolinite-rich clay indicates that low energy sedimentation of Colorado Plateau-derived detritus dominated distal Culebra Lake zones at depths >15 m; elevations of clay suggest that Culebra Lake-level stood at ~6400' for >5,000 years. Irregular sediment yields of piedmont drainages in a semi-arid climate and minor lake-level changes generated local coarsening up sequences in nearshore and shoreline zones that indicate east and south lakeshore migration. Sand and mudflow thickness indicate that sediment was delivered from the western piedmont in channels that concentrated sediment in fan-deltas and deltas along the lakeshore.

Elevations of materials that truncate lacustrine sequences suggest that significant volumes of Culebra Lake deposits locally were removed during the ~0.5 Ma between lake drainage and eruption of the 1.6 Ma Bandelier Tuff. Slump complexes that developed in the Bandelier above Culebra Lake clay probably began to fail when tributaries cut into and through lake deposits in Pleistocene time. Slump complex morphologies suggest that block formation probably propagated away from drainages as lateral support was removed sequentially. Slumping has completely removed Bandelier material from several mesa surfaces. Lacustrine deposits probably have controlled finger-mesa morphologies into the present.

The Upper Bandelier Tuff: Pyroclastic Flow Dynamics and Landscape Evolution, Puye Quadrangle, New Mexico
Stephanie K. Kampf
This study is an integrated examination of volcanic and erosion processes associated with the Lower Pleistocene Upper Bandelier Tuff in the Puye quadrangle, New Mexico. The area contains some of the most distal remaining deposits of Upper Bandelier Tuff. Published tuff classification systems for proximal areas apply imperfectly here. My study thus provides significant insights into pyroclastic flow mechanisms in distal areas, the landscape over which flows traveled, cooling unit characteristics and stratigraphic boundaries, and continuing evolution of the landscape. These analyses are based upon field observations and thickness measurements of Upper Bandelier cooling units in the Puye quadrangle and on adjacent areas of Los Alamos National Laboratory (LANL) as mapped by M.A. Rogers (1995).

Structure contour and isopach maps for Upper Bandelier cooling units suggest that the pre-Tshirege land surface exposed drainages trending W-E in the northern Puye quadrangle area and progressively cutting further toward the southeast in the southern Puye and LANL areas. Two broad canyons cut through the study area north of present Guaje Canyon, the largest of which might be considered a "paleo-Guaje Canyon." South of present Guaje Canyon, another major canyon, "Otowi Canyon" trended to the southeast. In the LANL area, one or more southeast-trending canyons may have existed in the central zone. The largest apparent drainage trended east in western LANL and bent almost directly south to connect with the Early Pleistocene Rio Grande. Little evidence of smaller tributaries remains, but one likely connected with paleo-Guaje canyon in central Puye quadrangle. Isolated remnants of Upper Bandelier furthest east in the Puye quadrangle represent fills of two small tributaries, one trending west to east and the other north to south.

Upper Bandelier pyroclastic flows were greatly influenced by this topographic base in the eastern Pajarito Plateau area. The first flow unit shows dramatic thickness fluctuations that reflect the paleo-topography. Unit 1 probably traveled through the Puye quadrangle in two major flow lobes constrained by paleo-Guaje and Otowi Canyons. Where these lobes intersect in a zone of relatively thin tuff cover, remaining unit 1 deposits contain abundant pumice concentrations and surge deposits. Subsequent flow units traveled over a relatively flat surface but still remained slightly constrained by topography. Unit 2 may have flowed through the northern Puye quadrangle in separate lobes traveling down remaining topographic depressions.

Following emplacement of the Upper Bandelier, subsequent drainage incision shifted in orientation and direction from its pre-Tshirege position. The deep incision of Guaje Canyon has formed through a zone where the cover of tuff is quite thin, whereas the most distal outcrops of Tshirege remain where thick flows of Upper Bandelier filled major drainages.

The Development of Cleavage and Graphite in Pelitic Schist near Taconian Thrust Faults, Mount Greylock, Massachusetts
Eliza S. Nemser
During the Ordovician Taconian orogeny, thrust faults carried the Late Proterozoic to Cambrian Greylock Schist westward over Cambrian and Ordovician rocks of the Stockbridge and Walloomsac Formations. Ratcliffe et al. (1993) interpreted the structure in the Greylock Massif as a recumbently folded thrust; this model was used to account for complex repetitions of the Greylock Schist and the Stockbridge and Walloomsac Formations. Deformational fabrics indicate that the structure may instead be dominated by cleavage in the Greylock Schist, which overprints an earlier schistosity, is most strongly developed near fault contacts and is only weakly developed in the cores of proposed recumbent folds, suggesting that these rocks were not folded post-emplacement. Textural evidence indicates that many of the rocks reached garnet grade prior to or during the development of the crenulation cleavage and were subsequently retrograded.

The repetitions of units may be explained by a model in which slivers of the Stockbridge Formation were dragged up along imbricate thrusts as the Greylock Schist overrode the Stockbridge Formation. Faults are typically mapped at the upper contact of the Walloomsac Formation, which is mapped based on the presence of graphite. However, graphite occurs in areas mapped as Greylock Schist and Stockbridge Formation as well as Walloomsac Formation; in each of these units, graphite-rich material is interspersed with graphite-poor material. The complex distribution of graphite in the rocks of the Greylock Massif suggests that graphite may not be a reliable stratigraphic marker. On the basis of geochemical models, I propose that graphite precipitated from carbon-bearing metamorphic fluids which migrated through fracture systems localized near faults during thrusting. Most of the graphite that was already present in these rocks prior to Taconian deformation and metamorphism must have been mobilized and redistributed during thrusting, as graphite is often concentrated in the planes of the crenulation cleavage. Much of the mapped Walloomsac Formation on the Greylock Massif may be reinterpreted as graphite-rich zones within the Greylock Schist and Stockbridge Formation; faults my be mapped in zones of particularly high graphite content.

Rates of Holocene Aggradation and Pedogenesis, Southeastern Puye Quadrangle, New Mexico
Catherine A. Riihimaki
Middle to late Holocene terraces and alluvial fans expose sequences of buried soils developed in sandy alluvium and fine eolian sediment along tributaries to the Rio Grande in the Puye 7.5' Quadrangle, northern New Mexico. Sedimentary sequences along arroyos and on the broad alluvial fan record mainly aggradation and equilibrium during the Middle to Late Holocene. The 14C ages of disseminated charcoal suggest that channels and alluvial fans aggraded from 2 to 7 m above modern arroyo levels during middle Holocene time. Sparse cultural and vegetation evidence indicates that channel downcutting began in historic time.

Soils formed on terraces during periods of relative surface stability and were buried by subsequent aggradation. Aggradational sequences contain numerous buried soil profiles, including one 3-meter sequence of 9 buried soils. Field evidence shows that buried soils are a few centimeters to decimeters thick and consist mainly of A/C profiles, Bw horizons, and weakly developed Bt horizons that contain carbonate coatings along fractures and pores. Laboratory analyses of texture and extractable constituents indicate that soils from the semiarid study area contain abundant fine material, CaCO3 and relatively little extractable iron compared with Holocene soils that developed on the adjacent Pajarito Plateau under more temperate climates. Silt plus clay content ranges from 5 to 85%, CaCO3 content ranges from 0.14 to 8.79%, and Fe2O3d content ranges from 0.12 to 0.38%. The abundance of fine material indicates that the carbonate and extractable iron contents in buried soils are primarily controlled by eolian input and that pedogenic processes are minor in the young soils of the semiarid environment. The 14C ages and laboratory analyses from buried soil profiles enable estimates of the rate of development of pedogenic characteristics such as loss on ignition (LOI), extractable iron, and CaCO3 and the rate of aggradation during middle Holocene time at one location. Calculations indicate rates of 5.8 g/cm2/ky for LOI, 0.072 g/cm2/ky for Fe2O3o, 0.38 g/cm2/ky for Fe2O3d, 4.9 g/cm2/ky for CaCO3, and 1.2 m/ky for aggradation during a 1.44-ky period. The age of nearby undated deposits and surfaces can be estimated using the degree of soil development at dated sites and continuity of aggradational sequences. These ages suggest that exposed deposits extend from the Middle Holocene to historic time, and may locally span the Holocene.

The 14C ages and estimated ages from degree of soil development suggest the following Holocene history of aggradation and incision in the southeastern Puye Quadrangle: delivery of coarse alluvium from upstream sites from ~8 to 5 ka, accumulation of silt-rich alluvium and eolian sediment from ~5 to 3 ka, abundant eolian activity from ~3 to 2 ka, and incision beginning at ~0.1 ka. Aggradation is out of phase with upstream terrace formation on the Pajarito Plateau, but in phase with aggradation and incision in nearby Tesuque Valley, New Mexico. Rates of accumulation of CaCO3 suggest the sequence of response to climate change of fluvial systems of the Puye Quadrangle is high eolian activity, erosion upstream, and deposition downstream.

Geochemistry and Tectonic Setting of the Early Proterozoic Metavolcanic Rocks of the Arkansas River Canyon, Howard to Royal Gorge, Central Colorado
Katherine M. Wearn
The Arkansas River Canyon area of central Colorado contains a significant and previously overlooked suite of Early Proterozoic bimodal metavolcanic rocks in the section extending 50 km upstream (west) from the Royal Gorge to the Pleasant Valley fault near the town of Howard. The felsic and mafic units are interlayered with a well-exposed series of biotite-quartz-feldspar gneisses, quartzites, and metapelites. The layered rocks were deformed and underwent regional sillimanite-grade metamorphism prior to the intrusion of the Garrell Peak pluton, which cross-cuts the metavolcanic units and gives them a minimum age of 1.65 Ga. The predominantly aphyric felsic units are characterized by primary fragmental textures and locally by relict flattened pumice lapilli. Amphibolites represent mafic flows and gabbroic sills; no pillow structures were observed.

Trace element data for 17 felsic samples by XRF and 12 by INAA show enrichment in both LILEs and HFSEs, and depletion in Sr, P, Ti, and Sc in MORB-normalized spider plots. REE diagrams show LREEs at about 100x chondrite and only slightly enriched over HREEs (LaN/YbN²5, along with small to moderate negative Eu anomalies. Geochemically these rocks closely resemble the less deformed Early Proterozoic aphyric metarhyolites near Salida, 15 km west of the western edge of the studied section (Boardman and Condie, 1986) and near Gunnison, 120 km to the west (Condie, 1986). The ranges and averages of most trace elements in the Arkansas River rocks are consistent with those of mature island arcs and active continental margins, both of which are components of regional tectonic models for Colorado showing rapid accretion of arc systems onto an enlarging continental during the Early to Middle Proterozoic.


Decompositions Via Linear Recurrences and Their Associated Asymptotics
Kariane Calta
A result from the early 1950's states that every natural number can be expressed as a sum of Fibonacci numbers. Later work determined the average number of terms needed in such a representation. In this thesis we extended and generalized these results by replacing the Fibonacci sequence by N-term linear recurrences having coefficients equal to one. Generalized two term recurrences with arbitrary coefficients are also investigated.

The Fibonacci Sequence Modulo p
Heath R. Dill
In this thesis we study the period length of the Fibonacci sequence modulo p, where p is a prime. In 1960, Wall produced divisibility results for such lengths in terms of p that naturally give rise to upper bounds for the period lengths. Here, using different methods, we produce new divisibility results which in many cases produce improved upper bounds for the period length. Fundamental to our method is a new algebraic structure on consecutive pairs of Fibonacci numbers.

On Parallelograms and Lattice Points in the Plane
Mimi Huang
This thesis investigates the areas of parallelograms in the two-dimensional plane. We consider parallelograms with center at the origin and directions of sides given with no interior integer lattice points except the origin. Szekeres found the supremum of the areas of such parallelograms and proved that the supremum can be at a particular direction of sides. Disregarding this particular direction of sides, we can attain a higher supremum for the areas of such parallelograms. Possible supremums of such parallelograms and the direction of sides at which the supremums are attained is shown in the paper. Cost minimizing networks model certain behavior of immiscible fluids in the plane. This paper proves the bound on the number of regions meeting around a point.

Z2 Actions, Flows, and Ergodicity
Andrew Raich
This thesis explores examples from ergodic theory. We investigate infinite measure preserving and nonsingular actions, with the primary focus on actions of the group Z^2. Chapter 2 studies finite measure preserving actions on the unit interval. Chapter 3 studies infinite measure preserving Z^2 actions to generate actions for which every direction has infinite ergodic index. We also construct a power weakly mixing Z^2 action, called the multistep action. Chapter 4 applies techniques of Chapter 3 to nonsingular type III_lambda Z^2 actions to generate a Z^2 Chacon action for which the basis transformations have infinite ergodic index.

The Planarity of Subgraphs in Outer-facial Drawings
Tristan Boardman Smith
This work is concerned with the problem of determining whether a given graph admits certain types of outer-facial drawings. There is a well-known characterization of those graphs which admit an outer-facial drawing having no edge crossings. Here we characterize those graphs that admit outer-facial drawings such that a given subgraph will have no edge crossings. We also consider the problem of whether a graph admits an outer-facial drawing that simultaneously minimizes the number of edge crossings and places a Hamiltonian cycle on the outer face. We provide a method that solves this problem for an infinite family of graphs.


The Period 1 to Period 3 Transition Through Chaos in a Mode-Locked Ti:Sapphire Laser
Christopher N. Elkinton
Chaotic behavior was observed using an ultrafast mode-locked Ti:sapphire laser. The laser was Kerr lens mode-locked and produced pulses of duration on the order to 50 femtoseconds. Following a known route to chaos--that of the transition from period 1 to period 3 regimes--we studied temporal, spatial, and spectral data. We used return maps, phase portraits, and power spectra as tools to allow us to observe behavior within the laser system characteristic of chaos. Analysis of this data leads us to conclude that we have observed a realm of chaos between regions of period 1 and period 3. Included in our data are pulse trains, optical spectra, time-averaged and pulse-resolved spatial profiles, and interferometric autocorrelations that help to characterize the period 1 and period 3 behaviors.

Behavior suggesting coupled transverse modes was also observed. By comparing pulse trains on opposite sides of the beam, spatial energy exchange was seen. We hypothesize that this transverse mode coupling affects the periodicity of the system.

Spatial and Temporal Nonlinear Dynamics in Kerr-lens Mode-locked Ti:Sapphire Laser
Robert A. Jenks
Passive mode-locking techniques, which to date have produced the shortest laser pulses, depend fundamentally on optical nonlinearities for their operation. Passively mode-locked lasers have also been observed to exhibit nonlinear dynamical and chaotic behavior. In this thesis, a numerical model that simulates nonlinear dynamical behavior is developed. The model relates the spatial and temporal nonlinearities operating in a mode-locked Ti:sapphire laser directly to its nonlinear behavior. The model also attempts to incorporate novel observations of energy exchange between simultaneously oscillating transverse spatial modes by using a coupled cavity analogy. Experimental measurements that can test the predictions of the model are discussed, and a data acquisition system that resolves the individual pulse characteristics necessary to make these measurements is presented. The predictions of the model are qualitatively tested using the data acquisition system, and shown to be in general agreement with the data.

A Mode-Locked Erbium-Ytterbium Optical Fiber Laser"
Aaron J. Kammerer
This thesis reports the improvements made to a mode-locked Er-Yb fiber laser. It is believed that mode-locking has indeed been achieved since the laser produces stable pulses of the minimum detection duration of the photodetector and oscilloscope in the laboratory of approximately 3.5 ns. The pulses have a fundamental repetition rate of 3 MHz that corresponds to the rate of one pulse at a time traveling around the laser cavity of 70 m. The pulses are extremely sensitive to polarization and fine adjustment of two polarization controllers is imperative to realize mode-locked operation. Verification of actual pulse duration through autocorrelation is a goal for future research.

Photoassociation Spectroscopy of Ultracold Na and the Development of Equipment to Laser-Cool Rb
Christian A. Murphy
Two separate but related projects are described in this thesis. First, we investigated the high rotational and vibrational energy levels of the 1g(3S + 3P) state of Na2 which exhibit large internuclear distances. These states are only accessible using photoassociation spectroscopy of ultracold (Å 0.5 mK) atoms. We used an apparatus at the National Institute for Standards and Technology in Gaithersburg, MD to do the spectroscopy. Our main goal was to find the frequencies of these states to a greater precision than had been achieved previously. The data we collected is presented here. Second, at Williams we are building an apparatus to do photoassociation spectroscopy of Rubidium. The design and construction of a grating tuned diode laser that has a stable enough frequency to sustain a trap is described. We have successfully constructed a laser that has a frequency stability of 5.0 MHz which was, in fact, our stability goal and is sufficient for our purposes.

Design and Construction of an Atomic Beam Apparatus for Precise Spectroscopy of Thallium
Peter C. Nicholas
This thesis details the design and construction of an atomic beam system that will be used to study thallium atomic structure in order to guide the refinement of thallium wavefunctions. Precise tests of the standard model's predictions of electroweak interactions in atomic systems require both precise measurements of effects due to the weak interaction and precise atomic wavefunctions. In atoms other than hydrogen, especially non-alkali atoms, approximate theoretical wavefunction calculations depend upon precise measurements of atomic parameters. Several atomic structure measurements using the soon to be completed atomic beam apparatus are discussed. An experiment to search for T-odd, P-even long range electron-nucleus interactions is also presented. Details of a laser frequency calibration technique, involving least squares parameter estimates based on transmission data from a Fabry-Perot interferometer, are given.

Precise Measurement of the Electric Quadrupole Amplitude Within the 6P1/2 to 6P3/2 Transition in Atomic Thallium
Leo L. Tsai
An experimental measurement of the electric quadrupole (E2) component of the 6P1/2 to 6P3/2 transition in atomic thallium is presented. Motivation for this and future measurements of thallium atomic structure stems from a recent 1% measurement of atomic parity nonconservation (PNC) within this same transition. In this experiment, an evacuated quartz cell containing thallium was heated to about 900¡ C. Light from an external cavity diode laser passed through a polarimeter containing the vapor cell and a longitudinal magnetic field. The relative size of E2 compared to the known M1 (magnetic dipole) amplitude was determined through careful line shape analysis of very high resolution absorption and Faraday rotation spectra. The preliminary value for [chi], defined as the ratio of E2 to M1, is: [chi] = 0.2358 ± 0.0006 ± 0.0028. This result is used to resolve a discrepancy between PNC measurements performed at the University of Washington and at Oxford. Based on our value for chi, a correction factor is suggested for the Oxford PNC measurement that brings the two results into statistical agreement.


Body-Focus in Women
A. Katherine Bair
Two studies were conducted. The first examined the body-, diet-, weight-, and exercise-focused messages in today's most influential print media sources. The second examined (1) the relationship of those influences to the self-schemata of college-age women and (2) the reactions of participants to women of different body types and eating habits in relation to the participants' body-focus. Analysis of Glamour, Cosmopolitan, and Good Housekeeping showed minimal increases in some exercise-focused messages and in some non-diet, non-exercise weight loss messages (diet pills) but found no change in the number of diet messages. The second study showed no relationship between fashion magazine readership and body-focus but did show significant relationships between body and meal size of a pictured woman and the number of body- and food- related remarks of a female observer. However, these significant results did not support the hypotheses. Limitations of the study and suggestions for future research are included.

Self-Presentation of Academic Achievement at Girls' Boarding Schools: An Exception to Female Modesty?
Andrea Burns
This study examined whether the established trend of "female modesty" in public situations would be found in high school girls attending single-sex boarding schools. Ninth grade students at four girls' boarding schools met with the experimenter in groups of 2 to 4 students at a time. During the course of an interview, they were asked to predict the grades they would receive at the end of the first semester. This was done under one of three conditions: a private condition, in which the predictions were written anonymously on note-cards, an anticipated public condition, in which the predictions were written, but with the anticipation of discussion with the group, and a public condition, in which predictions were made out loud. Following the interview, participants completed a three-part questionnaire, which measured their self-reported concerns and motivations during the interview, their gender-role orientation, and the degree to which they defined themselves through their relationships. It was hypothesized that participants in the public condition, those participants who were highly feminine, and those who were highly relational would predict significantly lower grades. Further, it was hypothesized that those participants in the public condition would demonstrate more affiliative behaviors, and make more modest remarks during the interview. It was found that, contrary to the hypothesis, participants in the anticipated public and public conditions significantly over-predicted their grades, while participants in the private condition were accurate. The hypotheses regarding a relational orientation, and participants' affiliative behavior and modest remarks during the interview were supported. The results suggest that the single-sex environment may elicit a different pattern of self-presentational behavior than coeducational situations.

The Effects of Nonverbal Cues and Ethnicity in Triggering In-Group Leader Preference
Grant W. Farmer
This research examined the effects of nonverbal gestures. It tested the hypothesis that when a subject must rely only on nonverbal cues as his/her information about others, this will instinctively trigger genetically wired information related to the nonverbal cues which will allow the subject to infer the level of similarity between himself and others. More specifically, the study looked at whether these n nonverbal clues would trigger wired information relating to a leader schema based on an innate desire to identify with others similar to us, and, if this is in fact true, would these automatic processes have an impact on voter preference? The study exposed 132 Williams College undergraduates to a political debate. The debate was debate was between two men, Paul Schell, who is Caucasian, and Charlie Chong, who is Asian. The videotape was edited into six different media variations in order to isolate specific channels of information presented to the subjects. The subjects were asked to rate each candidate overall on fifteen overall characteristics, and depending on which variation the subjects were exposed to, they also rated the two men either on appearance, voice, or both. It was predicted that of all the measures the visual variation would reveal the highest ingroup preference as measured by higher ratings for the same race candidate. The results indicate that ingroup preference is strongest in the visual variation in overall performance and overall leadership measures. The data also suggest that ethnicity plays a role in affecting subjects' perceptions of leadership, which in turn, affects voter preference. Discussions of secondary findings and alternative explanations are also included.

"I Didn't Do It!": Effects of Training on Judgments of Truth and Deception in the Interrogation Room
Christina T. Fong
The present experiments investigated whether trained and naïve observers can distinguish between true and false denials in a police interrogation. Study 1 tested the claims that observers trained in the verbal and nonverbal analysis of statements made in interrogation can distinguish between truthful and deceptive crime suspects. In Phase One, 16 participants committed either a mock crime or a related but innocent act. These suspects were then arrested and interrogated. In Phase Two, their videotaped interrogations were shown to 40 trained or naïve observers. The results indicated that trained observers were less accurate than naïve observers--but they were more confident and cited more reasons for their judgments. Study 2 replicated this study for individuals interacting in naïve or trained groups. Again, training had a negative effect on judgment accuracy, but it did not significantly affect confidence levels. These results shed doubt on the belief that police interrogators or juries can accurately distinguish between guilty and innocent suspects during an initial interview. Gender Issues and Identity Development.

The Effect of Patterns of Behavior on Self Control
Kristin M. Frentzel
Working with the delay discounting model of impulsiveness, in which impulsiveness is described as the choice of a smaller, earlier reward (SER) over a larger, later reward (LLR), we wanted to determine whether establishing a pattern of behavioral choices favoring larger rewards can increase a person's self-control. Three studies tested this patterning effect. In Experiment 1 (n=75), participants received a single randomly selected monetary reward at the end of the experiment. To examine the patterning effect, delays to both rewards were initially long, and were then gradually decreased so that a pattern favoring choices of the LLR was established. Again in Experiment 2 (n=40), each participant received a single randomly selected monetary reward. Here, we used a "staircase procedure" to change the value of the smaller reward in incremental steps while keeping the delay to both rewards fixed, thereby establishing patterns favoring LLR choices when SER values were small. Experiment 3 (n=5) differed from the other two experiments in that participants received food rewards, and they were reinforced after each patterning trial. The patterning trials were similar in structure to those of Experiment , but they were offered in "real time" with participants being telephoned on an approximately weekly basis and offered a choice trial.

Experiments 1 and 2 found no evidence of a patterning effect, but Experiment 3 provided suggestive evidence that patterning can, in fact, enhance self-control. The data suggest that simple response repetition patterns are not sufficient to increase self-control; rather, each element of a pattern of choices must be reinforced.

To Stroop Or Not To Stroop: A Novel Experimental Paradigm For Studying Impulsivity
Justin Houk
Relatively few studies with humans have examined impulsivity and self-control in controlled, laboratory settings. This may be due to the fact that we lack a good paradigm for eliciting impulsiveness. A new paradigm, the Escape-from-Stroop task, was designed and tested to see if it both supported as well as provided a way to advance current theory on impulsiveness. In this paradigm, participants were given an extremely difficult and aversive task to perform, based on the Stroop task. Impulsiveness was determined by how subjects chose to escape from the task. In Experiment 1 (n = 48), participants were found to (1) make choices consistent with the current theory of impulsiveness-that being that they preferred a larger, later reward to a relatively small smaller, sooner reward, but preferred a smaller, sooner reward when it was almost as large as the larger, later reward-and (2) be affected by a pattern of impulsive or self-controlled choices. In Experiment 2 (n = 38), it was shown that the Escape from Stroop task could be effectively used in situations with a discrete short term reward, but a long term conflicting reward that was spread out over time. Future applications of the new paradigm were discussed.

Modulation of the Short and Long-term Consequences of Maternal Separation by the Neurosteroid Allopregnanolone
Elizabeth Ward Kajunski
Early stress, in particular that of maternal separation, has been found to exert persistent and detrimental effects upon the brain. This thesis investigated the potential therapeutic actions of concomitant administration of the neurosteroid allopregnanolone, a potent positive modulator of the GABAA receptor, with the stress of maternal separation. Subjects were both 7 day-old and adult rats, divided into separated and non-separated conditions from days 2-6. Within each group of separated and non-separated rats there were rats receiving no injection, subcutaneous vehicle injection, and subcutaneous injection of allopregnanolone, 5mg/kg. On day 7, rats tested as neonates were given either no injection, vehicle, or one of 2 doses of allopregnanolone, intracerebroventricularly. Their vocalizations and behavior were then monitored. Adults were tested on the elevated plus-maze and monitored for activity. There were no significant differences in behavior observed between separated and non-separated controls. Interestingly, however, non-separated pups given allopregnanolone daily showed decreased anxiety in the PN7 test and a tolerance to the drug. Adult males in the same neonatal condition also showed a persistent anxiolytic effect of the drug. These results, while not supporting our hypothesis, suggest a functional change in GABAA receptors due to handling and postnatal exposure to allopregnanolone. In addition, they point towards further research into the neurological mechanisms underlying the potential stress-protective effects of handling.

Towards the Development of an Informant Questionnaire Sensitive to Alzheimer's Disease
Sarah C. Lurding
The goal of the present study was to develop a brief questionnaire that would be a sensitive screening instrument for Alzheimer's disease. With the rise in prevalence of AD, there is a need for a simple and short screening battery that could be implemented in a primary care setting. This study evaluated the Alzheimer's Disease Caregiver questionnaire (ADCQ) which is a self-administered, informant completed 56 question checklist that takes no more than 15 minutes to complete. It includes questions on memory, confusion and disorientation, geographic confusion, aphasia, apraxis, and personality changes, all of which are areas known to be disturbed in AD patients. The subjects who completed the ADCQ were either caregivers of AD patients (n=42) who were referrals to the Memory Clinic at Southwestern Vermont Medical Center in Bennington, VT or informants of healthy elderly controls who were community residing elderly (n=40). CART analysis was used to distinguish which questions were the best predictors of the diagnosis. The three discriminatory questions found by CART classified the sample with a sensitivity of 93% and a specificity of 100%. Taking the question from each axis that was most frequently answered "yes" to by AD caregivers, the sample was classified with a sensitivity of 98% and a specificity of 95%. Using all of the questions of the ADCQ, the sample was classified with a sensitivity of 91% and a specificity of 95%. This evaluation also found a high degree of test-retest reliability. There was a 95% consistency between informants' answers on the first and second questionnaire and there was a high degree of consistency for each question with a 95% consistency for all questions combined. The ADCQ shows promise as an accurate screening instrument sensitive to AD. Further data collection will identify 10-20 predictive questions that will ultimately become the ADCQ and which will be further validated. In further research, the ADCQ's value will be assessed in primary care setting.

Spirit of the Game: The Psychology of Gender and Competition
Sarah E. Nelson
Ultimate Frisbee was used as a medium to study the behavior and reasoning of men and women when confronted with potential conflict situations in athletic competition. High and low-level single-sex games were observed and videotaped, and a questionnaire was distributed to players from across the nation. For each game observed, frequencies of foul calls and contests were recorded, and for each taped game, discussions and conflicts were coded, as well as number of fouls actually committed (whether called or not). The questionnaire included questions about willingness to make and contest calls and certainty needed to make such calls, as well as more general questions about reasons for playing and definitions of "spirit of the game," the underlying philosophy of Ultimate. In the observed games, men called significantly more fouls than women, across levels, but there was not significant difference between the sexes or levels in frequencies of contests. When corrected for number of fouls actually occurring, as coded on the videotapes, the difference in foul calls also seemed to disappear. However, men and women answering the questionnaire differed significantly in their reports of willingness both to call and contest fouls -- men were more willing to do both. Men and women also differed slightly in their reasons for playing Ultimate when level of play was considered. Club women gave more competitive reasons that college women, while club and college men did not differ. Club men gave more social reasons than college men, while club and college women did not differ. Men also gave more game-oriented definitions of "spirit of the game" than women, who gave more person-oriented definitions of "spirit of the game" than women, who gave more person-oriented definitions. Both the relation of these findings to gender differences in aggression, assertion, and styles of interaction, and also the malleability of these gender differences are discussed in the thesis.

Consequences of maternal Separation for Immunological Responses to Later Stress in the Rat
Cynthia Jean Osterling
Maternal separation produces behavior agitation, increases in circulating levels of stress hormones, and impairments of immune function. Early separation has also been shown to result in behavioral and physiological vulnerability to subsequent stressors in later life. In this study, two measures of immune function, numbers of natural killer (NK) cells in the spleen and mitogen-stimulated production of the cytokine interleukin-2 (IL-2) were determined in adult rats that a) underwent maternal separation as neonates; b) underwent maternal separation as neonates and a brief swim stress as adults; c) underwent a brief swim stress as adults; and d) did not undergo either stressor. IL-2 production was significantly lower in rats that underwent acute swim stress (<.05). In contrast, NK cell numbers were similar in all treatment groups. Immunological sensitivity to swim stress in the rats that experienced maternal separation was not increased. However, when substantial systematic variability in both NK cell numbness and IL-2 production among different litters of rats were taken into account statistically, analyses revealed significantly lower levels of IL-2 in rats that underwent maternal separation compared to unseparated rats. Finally, administration of the anxiolytic neuroactive steroid allopregnanolone (5 and 10 mg/kg) did not alter the immunological effects of acute swim stress. The results of these experiments are consistent with previous reports of reduced functional immune responses following acute stress, but they provide only weak support for the hypothesis that early traumatic experience produces lasting immunological vulnerability to stress.

Can Early Stress Alter the Neurosteroid-GABA System in Neonatal and Adult Rats
Sharon H. Rackow
The neuroactive steroid allopregnanolone (3a-hydroxy-5a-pregnant-20-one) has been shown to be involved in the neurochemical stress response via its positive modulation of the GABAA receptor complex. This experiment investigated whether response to the neuroactive steroid allopregnanolone, a positive modulator of the GABAA receptor, would be altered in rats previously exposed to a chronic stressor - daily seven hours of maternal separation. Rats were tested as neonates (one week) and as adults using measures of both emotional behavior and activity. In neonates, allopregnanolone, as previously reported by this laboratory, decreased the number of ultrasonic vocalizations after a brief maternal separation. Non-separated pups vocalized more and were more active then separated pups, but were not more sensitive to allopregnanolone on either measure. As adults, the previously separated rats had a greater grooming response to a ten minute cold water swim test than non-separated subjects; again, there was no difference in the anxiolytic effect of allopregnanolone. These results suggest that while early maternal separation stress does produce a habituation response in neonates and a possible long-term sensitization response to later novel stress in adults, behavioral differences may not be due to developmental alternations in the neurosteriod system.

A Description and Preliminary Investigation of the Use of Solution-Focused Therapy in a Partial Hospitalization Program
Kristie A. Rogers
This study was conducted at the Partial Hospitalization Program (PHP) at the Berkshire Medical Center. The PHP generally treats patients who otherwise might be (and usually in the past have been) hospitalized for Bipolar disorder, Unipolar depression, personality disorders and related self-destructive behaviors, and other varied serious disorders. The therapists use Solution-Focused group therapy to help patients to think differently about themselves, their problems, and the solution to those problems. The focus of this research was primarily cross-sectional and examined two main questions: 1) Are certain types of clients' attributions correlated with hopelessness, and with their level of functioning? and 2) Are there differences in the types of attributions made based on diagnosis? Thirty clients enrolled in the program completed a set of measures including the Constructions of Problems Scale, the Basis-32, and the Beck Hopelessness Scale. The preliminary results suggest that there is a negative correlation between solution-focused thinking and hopelessness. In addition, the clients' level of functioning is inversely related to their degree of hopelessness. Other predictions regarding problem constructions and hopelessness were not supported. On a more exploratory note, four small case studies were included which examined cognitive changes that appear to have accompanied the Solution-Focused Therapy.

Stress and Antibody Responses in a Genetic Animal Model of Depression
Joanna R. Stevason
Major depression is associated with increased susceptibility to infectious illness and impairments of immune function. The aim of the current study was to examine whole-body antibody responses to immunization in Flinders Sensitive Line (FSL) rats, a promising animal model of depression, and in control Flinders Resistant line (FRL) rats. All animals were immunized with the novel protein antigen keyhole limpet hemacyanin (KLH), and blood samples ere drawn before immunization and 3,5,7, 11 and 14 days after immunization. Anti-KLH specific IgM and IgG serum antibody titers were then determined by enzyme-linked immunosorbent assay (ELISA). In addition, to determine strain differences in secondary antibody responses, the same animals were reimmunized 2 months later, and blood samples were drawn at the same intervals for determination of antigen-specific IgG titers. The FSL rats showed significantly lower levels of antigen-specific IgM and IgG after primary immunization and lower IgG levels after secondary immunization (<.05). Finally, no differences in specific antibody production in were observed in animals subjected to a pharmacological stress (intracerebroventribular administration of corticotropin-releasing hormone) compared to control animals. These experiments are the first to demonstrate substantially lower in vivo antibody responses in the FSL rats, and they provide support for the utility of this animal model in understanding physiological processes that may contribute to impaired immune function in clinical depression.

Pessimistic Explanatory Style and Athletic Performance
Jediah W. White
This study examined the effects of explanatory style on athletic performance. The Attributional Style Questionnaire was used to determine explanatory style for 188 college athletes. In Experiment 1, athletes completed a sport-relevant physical task, received false negative feedback, and completed the task a second time. I found that pessimists performed significantly more poorly after negative feedback than optimists. Experiment 2 divided 29 of the most pessimistic athletes into 2 programs. The experimental group received a six-session cognitive-behavioral intervention designed to transform them into optimists. The control group received a six-session discussion program that did not include optimism training. Upon completion of the programs, these athletes participated in Experiment 1. The cognitive-behavioral intervention significantly changed the explanatory style of the pessimistic athletes and resulted in improved athletic performance after negative feedback. The implications for sports performance and explanatory style intervention are discussed.

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