Student Abstracts

I tested the hypothesis that chaos areas on Europa may be the result of impactor penetration into a ductile subsurface. In laboratory experiments, ice projectiles were shot at velocities from 100 to 400 meters per second into layered ice targets consisting of ice over water, ice over slush, and ice over snow. Ice thicknesses varied from 0.5 cm to 4 cm. Three impact types were produced: non-penetrating craters, simple holes, and complete fragmentation. Non-penetrating craters correspond to recognized craters on Europa. Simple holes correspond to equant chaos. Complete fragmentation is analogous to blocky chaos. Impact type progresses from non-penetrating craters to complete fragmentation with increasing energy and/or decreasing ice thickness. Chaos boundaries correspond with observed impactor-penetration walls, and small craters surrounding candidate penetration features on Europa may represent secondary cratering. Measurements of over 2000 crater and chaos features from Galileo SSI images produced a combined exponential size-frequency distribution with craters dominating at small sizes and chaos at larger sizes. Limited overlap between the crater and chaos size-frequency distributions is the result of variable crustal thickness and a possible second chaos formation mechanism. My results suggest that chaos formation on Europa has been dominated by impactor penetration into a liquid or slush sub-surface layer. This exogenic mechanism for chaos formation differs strongly from other proposed mechanisms, and avoids the issues of energy magnitude and buoyancy.

The beautiful planetary nebulae that make up the late stages of low-mass star evolution can help us understand more about the evolution of stars like our sun. In particular, the delicate balance between a star’s mass and the CNO cycle can be explored by studying the elemental abundances of planetary nebulae. The differences in oxygen abundances between Type I and Type II planetary nebulae should indicate whether the CNO cycle is depleting oxygen within the more massive progenitor stars of the Type I planetary nebulae.

One notable difference in this study as compared to previous research is that the stronger [S III] lines 9069 Å, 9532 Å in the near-infrared were used instead of the weak [S III] 6312 Å emission line in order to more accurately determine the abundances of sulfur within the planetary nebulae. This increased sulfur reliability will then allow for a more reliable S/O ratio for the objects. This S/O ratio is used to compare the amount of oxygen between the Type I and Type II planetary nebulae.

Chemical abundances of 20 Type I planetary nebulae were calculated, and the data seems indicative of some oxygen depletion within the progenitor stars, but is not strong enough to draw definitive conclusions to that effect.

This thesis is the result of two independent projects. My work in the field of adaptive optics is detailed in Chapter Two, while the remaining three chapters begin with a theory behind solar observing and then detail my work on the solar telescope. The only major connection between the two sections is that they both made use of the Astronomy Department’s Phillips Webcam. I have some observational results, namely images and data that show the adaptive optics system isn’t feasible, as well as images of the Sun that demonstrate the further potential for the solar telescope, but they were not gathered with the intent of producing groundbreaking research. This thesis should be considered a labor of instrumentation: I have attempted to engineer a unique adaptive optics system and furthered the restoration of an aged solar telescope while integrating it with modern imaging devices.

In 2002, a team of scientists from Williams College observed the planet Pluto passing in front of a star, an occultation. The observations were made from the University of Hawaii’s 2.2-meter telescope at Mauna Kea Observatory. The existence of Pluto’s nitrogen and methane atmosphere has been known since the 1970’s and was probed during an occultation in 1988. Our data shows that Pluto’s atmosphere has expanded since 1988 even though Pluto’s distance from the Sun has increased since then. Our data also shows the presence of spikes in the intensity during various parts of the occultation. Such features were also observed in 1988. The source of these spikes may be due to variations in the atmospheric density. These observations present a strong case for a spacecraft mission to study Pluto. NASA’s New Horizons probe is currently scheduled for launch in 2006 and arrival at Pluto in 2015.

tRNA modification is a complex, mysterious process. One particularly intriguing modification is the transformation of uridine to pseudouridine (ɵ) at position 55; this modification occurs in >90% of the tRNA sequences analyzed across three domains of life, yet its function is not at all well understood. In order to gain greater insight into the function of this near-universal modification and the yeast enzyme that catalyzes the modification, Pus4, co-culture competition studies and systematic genetic array (SGA) analysis were performed. The co-culture studies clearly established that pus4ɢ mutants are at a competitive disadvantage compared to wild-type cells. This establishes that PUS4 and/or the ɵ55 modification have a positive effect on cellular fitness, thus providing a rationale for their evolutionary conservation. In addition, the SGA analysis performed revealed a number of genes that appear to have synthetic genetic interactions with pus4. Random spore analysis has preliminarily confirmed 32 of these candidates, which encompass genes in a diverse array of processes, including tRNA modification, protein synthesis, metabolism, and genes of uncharacterized function. In addition, a plasmid was constructed that, based on mutation of a conserved catalytic amino acid residue, should encode a catalytically inactive form of pus4, under the control of its natural promoter. This plasmid will be useful in determining if PUS4, like its E. coli ortholog TruB, has a modification-independent function.

As closed-ended learners, male zebra finches normally go through one song learning process, which concludes with song crystallization at about 90 days of age. Thereafter, the bird will sing only this crystallized song unless some form of outside intervention induces song plasticity. This song learning process results in a representation of a bird’s own individual song in the high vocal center (HVC) and other song production nuclei in the brain. Thus, a recording of a bird’s own song will elicit a more robust response from auditory response neurons within HVC than will any other sound stimuli. The bird will reenter a period of song plasticity and crystallized song will change, however, if one half of the bird’s vocal organ, the syrinx, is uncoupled from the brain. A region of the brain that is normally required for proper song learning, but not necessary for adult song production, LMAN, must be intact in order for this nerve-damage-induced plasticity to occur. This suggests that song plasticity corresponds with plasticity in the brain itself. In this study, the right half of the syrinx was denervated in adult male zebra finches, causing the subjects to alter their crystallized songs. Recordings of each subject’s own song before and after nerve injury were presented to each bird after song recrystallized. In none of the six subjects studied did HVC respond most strongly to intact, crystallized song. All six birds showed the greatest HVC response for one of their own songs recorded after nerve damage, and five of the six subjects showed increased responses to songs that contained new features not seen in original song. These results suggest that, under certain circumstances, brain plasticity is possible in male zebra finches during a phase of life when this normally would not be the case.

In order to develop a protocol for the study of song dialects and cultural evolution based on the use of molecular markers we attempted to isolate microsatellite loci from the House Finch, Carpodacus mexicanus. We tested a new procedure for this isolation, involving several microsatellite enrichment methods and the use of the non-palindromic restriction enzyme BseYI to create unique sticky ends. This procedure was not successful, as we were not able to isolate any new loci, and it showed little promise for future work. We also tested both microsatellite and non-microsatellite genetic markers on a sample of birds from two different dialect regions to determine their relatedness and found these two types of markers did not behave similarly. Using microsatellite loci we were able to determine that differences in song pattern do not serve as a barrier to interbreeding amongst neighboring populations in this species. We also found intriguing evidence that eastern House Finch populations may be lacking in genetic diversity and genetically divergent on a large scale.

Agrobacterium tumefaciens incites crown gall disease on wounded dicotyledonous plants by exporting both DNA and proteinaceous virulence factors across the bacterial membrane system using a Type IV secretion system (T4SS) encoded on the endogenous tumor inducing (Ti plasmid. This T4SS is comprised of virB and virD4 gene products. The virB operon is under the transcriptional control of the acetosyringone (AS)-inducible vir promoter. In addition, the virB operon in the Ti plasmid pTiA6 in the wild-type A. tumefaciens strain, A348, contains an additional promoter embedded between virB6 and virB7. Through the use of a reporter gene fusion and β-galactosidase liquid assays, the virB internal promoter was further characterized. By cloning the analogous virB internal promoter sequence from pTiC58 in the wild-type A. tumefaciens strain C58 into a promoterless lacZ construct and performing β-galactosidase liquid assays, we determined that pTiC58 does not contain an internal promoter analogous to the one found in the virB operon of A348. To investigate whether traffic through the VirB-D4 T4SS affects internal promoter activity, we studied the effect of T4SS-mediated plasmid translocation on pTiA6 virB internal promoter activity measured from β-galactosidase liquid assays. virB internal promoter activity did not differ between a wild-type A. tumefaciens strain carrying a broad host range plasmid and the same wild-type A. tumefaciens strain that did not carry a broad host range plasmid. Further, a clean deletion of the VirB-D4 T4SS component, VirD4, did not result in abnormal internal promoter activity, indicating that the VirD2-dependent drop in internal promoter activity that is observed under vir-inducing conditions is not mediated through VirD4. A construct that was expected to insert the lacZ reporter gene downstream of the internal promoter in the context of the entire virB operon did not exhibit significant β-galactosidase activity and therefore did not give conclusive data about the virB internal promoter activity in its naturally occurring context. These results are consistent with a working model, which predicts that the virB internal promoter directs constitutive transcription of VirB8 in order to nucleate assembly of the T4SS immediately upon plant wounding.

Heat shock proteins (HSP’s) are highly conserved proteins whose expression is induced in response to heat shock. They act as molecular chaperones by helping to fold or re-fold proteins after a thermal event and by targeting misfolded proteins to degradative machinery within the cell. One particular HSP that is highly conserved in vertebrates is the small HSP27. This protein functions in neuronal and non-neuronal differentiation, conveying resistance to apoptosis, and providing protection against oxidative stress.

Importantly, HSP27 is also implicated in actin regulation in a variety of cell types, functioning primarily as an actin-capping protein or as an actin-stabilizing protein. HSP27 localizes to dynamic structures at the leading edge of motile cells where the protein’s association with actin translates to a broader role in cell motility. More recent evidence points to the fact that HSP27 is present in vertebrate neuronal cells and, more specifically, in neuronal growth cones. Growth cones navigate by translating cues from the environment into changes in the actin and/or microtubule cytoskeleton, allowing individual axons to migrate along specific trajectories.

Based on its role as an actin regulatory molecule, it seems likely that HSP27 may mediate axon outgrowth and/or guidance by regulating the actin dynamics in neurons. I have examined the expression of HSP27 in zebrafish embryos over the course of development and found that it is expressed in neurons throughout the nervous system. In addition, I have performed loss-of-function analysis, which revealed that, in the absence of HSP27, axon outgrowth defects are observed. In summary, the results are consistent with HSP27 playing a role in axon outgrowth.

A spinal cord crush at the spino-medullary level results in the loss of function below the wound in goldfish, Carassius auratus. Miraculously these animals recover swimming, feeding, equilibrium and startle responses a few months after injury (Zottoli and Freemer, 2003). However, not all central neurons (i.e. nerve cells confined to the central nervous system) contribute to this behavioral recovery. For example, a pair of identifiable nerve cells, the Mauthner cells (M-cells), morphologically regenerate after injury but the growth follows aberrant pathways and ultimately does not contribute to the recovery of startle responses that it is known to initiate in normal fish.

A pair of Mauthner cells (M-cells) are located on either side of the midline in the medulla oblongata of the goldfish brain. These neurons can be identified by their large size and characteristic extracellular negative field recorded near the axon hillock-initial segment region. This initial region is encased in a specialized structure called the axon cap, a structure surrounded by a ring of glial cells. The axon cap can be divided into a central and peripheral zone based on the input types each portion receives.

Cyclic adenosine monophosphate (cAMP) and its analogues mediate a broad spectrum of events such as promoting neurite growth (Cai et al., 2001) and act as axon guidance cues (Song et al., 1998). Recent studies in larval zebrafish have demonstrated that dibutyryl-cAMP (db-cAMP), a membrane permeable analogue, injected on the plasmalemma of damaged M-cells “converts” the cell from a non-regenerating state to a regenerating one. In fact, the cAMP activated growth is directed caudally and results in the return of function (Bhatt et al., in press). In this study, we first verified that we could reliably inject a visible tracer, Horse Radish Peroxidase (HRP) into specific portions of the axon cap. Using the information gained through HRP injection, we localized db-cAMP injections to specific portions of the cap region of damaged M-cells in the adult goldfish to determine whether db-cAMP could facilitate morphological and ultimately functional regeneration.

We saw that db-cAMP stimulates all injected M-axons to regenerate and that db-cAMP enhances growth of injected M-axons past the wound site. Most remarkable is that this growth occurred in 20 days compared to the lesser growth by control M-axons in 30 days. Our results support the findings of Bhatt et al. (in press) that cAMP can enhance M-cell regeneration and indicate that cAMP also has significant effects in an adult model. These results have profound implications for possible reversal of abortive regeneration and possible functional regeneration in mammals.

The developmental mechanisms of polychaete segmentation have not been thoroughly characterized, although they are the best representatives of the annelid phylum. Our project examines segment formation in the polychaete Capitella capitata by describing the spatial and temporal patterns of cell proliferation that give rise to segments during development. Immunostaining Capitella with an antibody against HH3, which targets rapidly dividing cells, reveals a distinct progression of cell proliferation in the trunk region of the trochophore larva. There are four abrupt increases in cell proliferation during the first 96 hours of development. Cells along the extent of the anterior-posterior body axis begin to divide simultaneously in the ventral-lateral region of the larva at 46 hours after development commences. Cell proliferation continues to increase until stripes of cells in the ventral region of the trunk begin to divide simultaneously at 77 hours; when morphological boundaries become visible, it is clear that each ventral stripe corresponds to a single segment. Both of these events indicate that segment formation in Capitella is synchronous. This temporal mechanism of segmentation is atypical among the polychaetes, but a comparison of the spatial distributions of rapidly dividing segmental precursors suggests that the spatial characteristics of segment formation in Capitella may still be common in the annelid phylum.

An efficient synthesis of the C16–C25 triene fragment of antiviral marine natural product hennoxazole A is obtained in nine steps from commercially available (S)-3-butyn-2-ol with an overall yield of 16.3%. A high yielding, stereoselective [2,3]-Wittig-Still rearrangement is utilized to establish the geometry of the C20–C21 Z-trisubstituted alkene. A key fragment coupling between a C8–C15 bisoxazole system and the C16–C25 triene fragment provides validation of our approach toward hennoxazole A. This model coupling and subsequent deprotection of the C13 protecting group are accomplished smoothly in two steps with a 75.1% yield overall.

Mammalian erythrocytes undergo a process of enucleation as they mature. In their functional form, mammalian erythrocytes do not contain any genetic material, and are essentially ‘bags of hemoglobin.’ Avian and amphibian erythrocytes do not undergo the enucleation process and, therefore are nucleated in their functional form. However, no transcription or replication occurs in these nucleated, mature erythrocytes. The DNA is essentially held in an inert state.

The DNA within these nucleated erythrocytes is packaged in the same manner as it is in transcribing and replicating cells within the chicken with one exception. The typical chicken cell has the linker histone H1 (A and B) present in the nucleosome (the basic, repeating unit of packaging in chromatin). In the erythrocyte nucleosome, a variant of H1, named H5, is present in a four to one ratio over H1. The incorporation of H5 inactivates the erythrocyte nucleus and holds the DNA in an inert state.

The goal of this project is to compare the strength of binding of H1 and H5 to chicken erythrocyte chromatin. To achieve this, erythrocyte chromatin was isolated from chicken blood. This chromatin was then characterized by gel electrophoresis and thermal denaturation. The linker histones were selectively stripped off using elevated salt concentrations and the stripped chromatin was recovered. This stripped chromatin was characterized in the same manner as the whole chromatin.

From the 1950s to the 1970s, Sprague Electric Company (SEC) of North Adams, Massachusetts, used polychlorinated biphenyls (PCBs) in its manufacture of capacitors. Although the plant closed at the end of the 1970s, PCBs continued to leach into the river from contamination at the former SEC site. Later studies estimated that approximately 20 pounds of PCBs were entering the Hoosic River each year from waste buried near the plant. As probable carcinogens, these PCBs posed potential health threats to citizens using the river downstream of the SEC. Finally, in 2000 a cleanup effort was launched, the landfill was contained, and large amounts of contaminated dirt were removed to prevent PCBs from entering the Hoosic. After the cleanup and prior to this study, however, no research had been conducted investigating to what extent these highly stable, persistent pollutants continue to exist in the Hoosic ecosystem.

This study sought to measure what levels of PCBs remain in the river four years after the remediation of the SEC site. We sampled riverbank soil from Adams, Massachusetts, to the Vermont/New York border in hopes of identifying trends in PCB dispersion. We focused primarily on recreational sites to gain a better understanding of what levels of PCBs recreational users of the Hoosic would encounter on a regular basis. Additionally, we studied PCB levels in crayfish and brown trout to investigate how PCBs continue to bioaccumulate. We also conducted these studies so we could compare our results to previous studies on the same species, thereby gaining a better understanding of how PCB levels may have changed since the SEC cleanup in 2000.

Jerangolid D is a secondary metabolite produced by the myxobacterium Sorangium cellulosum (strain So ce 307). A structural variant of jerangolid D exhibits potent antifungal activity against the developing cells of Hansenula anomala by a mechanism that is believed to be similar to ambruticin, a more well-known myxobacterial isolate. Jerangolid D bears an appealing structure from a synthetic point of view. It contains two asymmetric dihydropyran-based ring systems and four stereogenic centers, one of which is in a doubly-allylic location.

In this work, we propose a total synthesis of the natural product. Our synthetic route utilizes a three-step sequence that was previously developed by the Smith group for establishing asymmetric dihydropyran-based ring systems. Using the experience from synthesizing the kavalactones, this aldol – homologation – lactonization sequence will be applied to both rings of jerangolid D. The stereochemistry at the doubly allylic can be approached by replicating the asymmetric hydroformylation reaction used by Jacobsen in his total synthesis of ambruticin. Intercepting his route provides a reliable method of establishing a potentially difficult structural component.

Reactions through the cyclization of the first ring of jerangolid D were successful. However, single nucleophilic addition to this lactone was not as straightforward. To avoid mixtures of starting material, desired product, and overaddition material, a sulfone-based route was attempted. Although addition of a sulfone-stabilized anion was successful, desulfonation proved to be difficult. Both modifications of the sulfone approach and new synthetic strategies are proposed as alternatives.

A kinetic model for the HIV-1 Rev protein was developed by drawing upon the literature to formulate a set of differential equations modeling the behavior of Rev and its various associated factors over time. Several sets of results were presented demonstrating the possibility of oscillations in the concentration of these factors. Finally, these results were analyzed and future directions for the project were discussed.

A six molecule library, containing the canthine alkaloid, benzocanthinone, one known benzocanthinone derivative and four previously unsynthesized isomeric compounds was successfully synthesized. Each synthetic scheme contained two similar key steps, first the base-catalyzed formation of an amide bond and second the radical induced intramolecular cyclization of an aryl halide. The productivity of the cyclization step on a variety of relevant starting materials was analyzed to understand better the scope of this reaction’s effectiveness.

Mixtures of substituted triphenylene molecules with triimide have been shown to form materials in which donor/acceptor behavior causes the molecules stack in an alternating fashion. At certain temperatures, some of these mixtures display liquid crystalline properties. The degree of the donor/acceptor interaction is determined by the donor properties of the triphenylene’s electron-rich π system and the acceptor properties of the electron-poor triimide. The proximity in energy of the HOMO of the triphenylene and the LUMO of the triimide determines the strength of the donor/acceptor interaction. In our work, we have shown that changes to the substituent groups on the triphenylene may change the strength of this interaction, affecting both the HOMO-LUMO energy gap and the mixtures’ liquid crystalline properties. We have also probed ways of tuning the electronic properties of the triimide by creating hydrogen-bonded supramolecular complexes. We did not find NMR or IR spectroscopy to be useful in characterizing these supramolecular complexes, but CV experiments on mixtures of triimide with certain compounds (N, N'-diethylthiourea, 2-guanidinobenzimidazole) show that their hydrogen-bonding interactions with triimide may be used to modulate the electronic properties of the molecule. So far, we have been unable to measure the extent of this change or characterize its effect on the donor/acceptor complexes formed by the triimide with the substituted triphenylenes.

The discovery of cisplatin as an effective anti-tumor agent and the subsequent determination of its mode of action led to the synthesis of many related structures in hope of synthesizing a more powerful drug. This paper begins with describing the ways in which cisplatin is believed to lead to cell death, highlighting several important components. Furthermore, the means by which the body detoxifies cisplatin are also brought to focus. The knowledge of these biological processes is taken into account, and various structural components necessary for a more active drug are outlined.

The ability of a bioxazoline ligand to bind to platinum, prevent attack of cellular thiols, and allow for the introduction of chirality indicates that this functionality is worth pursuing. The bioxazoline ligands were first synthesized in several steps from enatiomerically pure amino acids as previously described in literature. The real synthetic achievement accomplished is the creation of the platinum-bioxazoline complexes.

Both enantiomers of 4,4’-diisopropyl-2,2’-bioxazoline platinum-diiodide as well as both enantiomers of 4,4’-dimethyl-2,2’-bioxazoline platinum-diiodide were synthesized in 3.75% and 22% yield, respectively. S,S-4,4’-dimethyl-2,2’-bioxazoline platinum-dichloride was synthesized in 18.9% yield from the corresponding diiodide, and S,S-4,4’-diisopropyl-2,2’-bioxazoline platinum-dichloride was synthesized in 16.5% yield from the corresponding diiodide starting material. The reactive intermediate in the scheme from the diiodide to the dichloride product is the diaqua compound, which was synthesized for both enantiomers of the methyl and isopropyl compounds and subsequently remained in solution throughout the following reaction.

The ability of the S,S diaqua methyl and isopropyl compounds to bind to the nucleotide dGMP was also examined. It was determined that the novel platinum complexes bind to the nucleotide exactly as cisplatin does, at the N7 nitrogen.

Finally, an experiment to determine the extent of complex binding to double-stranded DNA was begun, in which the melting temperature of the non-platinated double-stranded DNA determined corresponds to that described in literature. The attempted reaction of the complex with single stranded DNA and a portion of the subsequent purification of DNA are described.

Today, almost all software uses on dynamic memory allocation. In some programming languages, it is impossible to even write “Hello World!” without implicitly calling the allocator. However, the costs of dynamic memory allocation on cache performance are relatively unstudied. This work explores the effects of dynamic memory allocation on cache performance, as well as methods to make memory allocators cache-conscious. We use profiling techniques to build custom memory allocators. These allocators contain statically generated memory layouts that arrange memory in a cache-conscious manner for previously analyzed workloads. We demonstrate performance gains resulting from these cache-conscious allocators and analyze the cache performance of different memory layout strategies. We provide an open source foundation to aid in future research that is fully compatible with all standard C allocation functions.

The Hvammur-Breidin area of southern Vatnsdalsfjall in northwest Iceland lies 15 km east of an abandoned rift zone that was an active spreading center from 15–7 Ma. It contains an unusual and dramatically well-exposed monoclinal flexure that deforms a 150 m-thick sequence of late Tertiary volcanics produced during the waning stages of rift activity. The lavas in the sequence dip to the west up to 44º and maintain a constant thickness up to the fold axis, which trends north-south. In the trough of the monocline is a thick basaltic unit, the Hjallin Lens, that was originally mapped as an intrusion but has been reinterpreted as extrusive (McClanahan, 2004). In this study, the evolution of the monocline is described and related to a change in magmatic processes that ultimately led to the eruption of the Hjallin Lens basalt.

Overlying the monocline sequence and underlying the Hjallin Lens, an intervening sequence of thin basalt flows leading upwards to a thick lahar thickens from ~30 to 100 m into the trough of the monocline. This middle sequence contains low-angle unconformities and minor faults that suggest structural adjustment concurrent with its emplacement. A major fault that post-dates the eruption of the flows in the monocline and predates the deposition of the lahar is inferred to have displaced the monocline sequence just east of its fold axis, with 150 m of normal slip to the west.

Flows that are part of the monocline (M sequence) and those that overlie the monocline (O sequence) are mutually distinct in terms of petrography and geochemistry. The M sequence contains several silicic units (rhyolite, dacite, and rhyodacite tuff) interlayered with a wide variety of basalts, including weakly porphyritic intergranular basalt, coarse-grained ophitic basalt, olivine basalt, and plagioclase-ultraphyric basalt. In contrast, basalts in the O sequence are all fine-grained and intergranular.

Volcanic rocks from both the M and the O sequences are subalkaline. Bivariate plots of major oxides against MgO reveal a general fractionation trend involving both sequences, in which the O sequence and Hjallin Lens basalts are the most highly evolved differentiates. With respect to increasing SiO2, M and O basalts characterize two distinct trends, and a high degree of compositional variation exists within the M sequence. Basalts from both sequences are enriched in lighter, incompatible elements (Th and Rb), characteristic of plume-associated mid-ocean ridge basalt. The degree of enrichment among the M-sequence basalts is varied but increases somewhat upsequence. Both M and O basalts have Zr/Nb ratios of <10, also a signature of plume influence, and a substantial gap in Zr and Nb abundance occurs between the M and O sequences.

Two new 40Ar/39Ar dates, one from the top of the M sequence (7.62 ± 0.32 Ma) and one from the Hjallin Lens (6.98 ± 0.18 Ma; McClanahan, 2004) bracket a 0.60–1.14 m.y. window for the formation of the monocline, major displacement of the monocline along the normal fault, and the eruption of the O sequence. The monocline is interpreted to have formed incrementally during eruption of the O sequence above an upward-propagating normal fault. The structure is likely due to local subsidence caused by extension, and it provided a topographic depression for the ponding of the thick Hjallin Lens basalt flow during a new phase of magmatism.

Data collected by five expeditions, spanning 36 years, shows that the Mary Creek reef complex (MCRC) is shallowing and that Acropora palmata colonies in the MCRC, after experiencing a severe decline in the 1980s, have begun to repopulate the reef. Analysis of five airphotos taken between 1965 and 1999 shows that all three reef lobes of the MCRC have decreased in size since 1983, and the westernmost reef lobe has decreased by more than 50% since 1965. Bathymetric data from 1968, 1998, and 2004, show conclusively that the backreef lagoon is experiencing shallowing at a rate of approximately 3.2 cm/year.

The backreef lagoon infilling is not attributable to in-situ algal sediment production, nor to an increase in storm events. However, the progressive infilling may be related to regular storm transport of sediment over the reef crest.

We observed approximately 70 A. palmata colonies in the MCRC, a substantial increase over the population observed in 1998.

Plio-Pleistocene basin and ramp deposits are exposed at many sites along the southern Baja California coast of the Gulf of California. These deposits give an important record of the opening of the Gulf of California at about 5 Ma. However, most of these basins record only part of the Plio-Pleistocene history. Arroyo Blanco on Carmen Island, located 25 km offshore of the town of Loreto, provides access to a substantially complete record of Pliocene and Pleistocene ramp, terrace and rocky-shore environments in the context of a large carbonate basin.

The Arroyo Blanco Basin on Carmen Island covers about 3.3 km2 and includes at least 61 m of conformable strata measured normal to bedding plane. Satellite imagery (TM and ASTER data) was used to evaluate possible deposits and their relationships and to expedite fieldwork. These data were also used for mapping basin and terrace features. A stratigraphic column for the basin was constructed to differentiate between limestone, conglomerate and clay-pan deposits. In addition, four marine terraces were identified on the truncated east side of the basin, at 12, 37, 58 and 68 m elevation above sea level. A possible fifth terrace may exist at 72 m elevation. A biostratigraphic column was constructed using important index fossils such as the pecten Argopecten svedrupi (Lower Pliocene), the echinoids Clypeaster bowersi (Lower-Middle Pliocene), Encope shepherdi (Middle Pliocene), and Encope grandis subsp. inezana (Pleistocene); the gastropod Turitella gonostoma (Pleistocene), and the coral Pocillopora robusta (Pleistocene). All Pliocene deposits are conformable, and Lower Pleistocene deposits sit conformably on these deposits. The origin of the basin is set at roughly 5 Ma to include the upper Lower Pliocene. The Plio-Pleistocene boundary is set tentatively at about 47 m up section, or roughly 50 m above present sea level. Eight thin sections were made from samples of representative strata, and these support field interpretations of deposits as rhodalgal calcarudite limestones with a minor volcanic lithic component.

All larger scale bedding in the basin shows a consistent synsedimentary slope of 4-6° along about 0.8 km dip. Thick rhodalgal calcarudite/calcarenite facies indicate predominant current and offshore-storm deposition (~64%). Less prevalent and thinly bedded units of conglomerates (~15%) indicate periodic terrestrial runoff, probably related to onshore chubascos. Pecten-rich strata (~21%) indicate periods of relatively calm background deposition related to nearshore processes. Finally, horizontal red clay beds indicate back-beach or shallow intertidal subaerial deposits (< 1%). These are left undisturbed in their original horizontality. These clay beds act as a ‘mega-geopetal’ device that allows for the recalculation of true ramp thickness as a function of vertical accumulation on a slope. At Arroyo Blanco, this true thickness is 153 m. While other basins in the Gulf show evidence for tectonic tilt, Arroyo Blanco Basin does not.

In general, the Arroyo Blanco Basin strata indicate prolonged relative marine transgression in a sizeable basin dominated by rhodalgal facies. The thickness is theorized to be related to prolonged subsidence of the basin, as can be seen from the continuous development of a carbonate ramp. There are a few possible indicators of regressive periods, namely red clay beds and possible shallow-water sedimentation, in the form of channel flow in three of the conglomerate beds. After a period of subsidence ranging from the upper lower Pliocene to at least the lower Pleistocene, the sediments of Arroyo Blanco underwent uplift relative to sea level. This began with a period of relative sea level low-stand and the formation of a Pleistocene beach deposit that currently caps the stratigraphy of the basin. The basin subsequently experienced episodic uplift during the Pleistocene. At least four marine terraces were cut into the Pliocene substrate, leaving evidence of Pleistocene rocky shorelines, including sorted, red algae coated cobble deposits, bored surfaces, gastropods and corals.

The basin is bounded to the southwest by a normal fault cutting all four Pleistocene terrace deposits and normally offsetting Pleistocene deposits along its margin. Also, tectonic uplift since the Lower Pleistocene has been considerable.

Comparison of these deposits to other basins, including Punta El Bajo (northern Loreto Basin), Arroyo El Mangle, deposits at the base of the Concepcion Peninsula, and Punta Chivato indicate that the Arroyo Blanco deposits are exceptional for the thickness of their rhodalgal facies. Additionally, this site provides an important master-record of conformable Pliocene and Pleistocene strata for the entire Gulf of California.

Faults on the Aegean island of Syros, part of the Cycladic archipelago southeast of mainland Greece, record the complex tectonic history of the Mediterranean region following blueschist metamorphism. The Cyclades are in the Attic-Cycladic crystalline belt, a series of high-pressure, low-temperature metamorphic core complexes derived from subduction between microplates during the Alpine orogeny. Beginning approximately 30–25 Ma, collision in the Mediterranean gave way to post-orogenic extension (Jolivet and Faccenna, 2000) and exhumation of the Aegean blueschist terranes by low-angle normal faults and detachments in a back-arc setting (Okrush and Bröcker, 1990). Although Syros is famous for its exposures of high-grade metamorphic rocks, the island’s high-angle normal faults with well-developed breccia zones have not been studied in detail. It is uncertain whether the high-angle normal faults are synchronous with or younger than the large-scale normal faults responsible for Aegean blueschist exhumation. Three high-angle faults are located along Syros’ western coast at Cape Diapori, the northernmost tip of the island; the western end of Cape Katakefalos; and on the Charasonas headland near the Grotto of St. Stephanos. The faults are arranged en echelon, strike NW–SE, dip >60º, and have throws no greater than 30 m. All three breccia zones contain similar fault products, primarily equidimensional angular marble fragments in a cohesive, finely ground carbonate matrix. No schist clasts are evident in the breccia. Field observations and petrographic descriptions provide the context for fluid-inclusion analyses of fault material from each of the breccia zones, which help constrain ambient conditions during faulting. Fluid inclusions in crystalline quartz from a fault-related vein at Diapori show homogenization temperatures of 140–150ºC and freezing temperatures of –2.9 to –0.9ºC; the latter suggest a fluid composition of 1.5–4.7 wt% NaCl. Fluid inclusions in crystalline quartz from breccia matrix at Charasonas contain at least three fluids with homogenization temperatures of 140–160, 200–210, and 220–240ºC. Freezing temperatures of –5.9 to –5.4ºC suggest a fluid composition of 8.5–9.0 wt% NaCl. Petrographic evidence suggests brittle deformation during faulting; brittle deformation tends to occur in low-temperature environments at shallow crustal levels. The three faults occur at or near the tips of the western peninsulas, and may be isolated parts of a NW–SE-trending graben with a W-dipping plane on its NE side and an E-dipping plane to the SW.

The Hjallin Lens is a thick, lenticular basaltic unit in the Vatnsdalsfjall Ridge near the southern end of the Skagi Peninsula in northwest Iceland. The extensive volcanic and intrusive units that define the geology of this region are products of a unique interplay between the mid-Atlantic spreading ridge and the Iceland plume. While no longer active today, the region was the site of prolific volcanic activity between 7 and 15 Ma. The Hjallin Lens was first interpreted by Annells (1968) as a shallow-level, olivine-free tholeiitic laccolith. However, petrographic, geochemical, and geochronologic analyses, coupled with extensive field observations, have yielded support for an alternate interpretation: that the lens is in fact an extrusive feature, representing the ponding of a thick basaltic flow in a pre-existing topographic low.

The Hjallin Lens is exposed on the western flank of the Vatnsdalsfjall ridge. It extends approximately 3000 m in the NNW–SSE direction and up to 800 m in the ENE–WSW direction. The lens reaches its greatest thickness (over 150 m) near its southern end. The lithology of the lens is virtually uniform throughout: the rock is a very hard, fine-grained, aphyric, non-vesiculated basalt that has cooled into sharply defined columnar joints. Petrographic analysis revealed that the lens basalt contains small, scattered phenocrysts of plagioclase and, less frequently, clinopyroxene. Its groundmass is composed of roughly equal amounts of intergranular clinopyroxene, plagioclase, and a significant amount (15-40%) of ilmenite and other opaque minerals. Geochemically, the lens rock can be classified as a tholeiitic, sub-alkaline basalt, with trace-element signatures (Zr/Nb<10; enrichment in incompatible elements) that indicate a plume overprint on N-MORB geochemistry. The striking textural, mineralogical, and geochemical homogeneity of the Hjallin Lens indicates that the entire body must have cooled rapidly at the surface, without any internal differentiation.

The lens is underlain by a rhyolitic ash flow tuff along a sharply defined contact. At the southern end of the lens, the ash flow tuff is underlain by a poorly lithified sediment with well-preserved specimens of carbonized and silicified organic material. The upper contact of the sediment with the ash flow tuff is sharp; at its base, however, the sedimentary unit grades into a much coarser, polymict lahar. The presence of these relatively undisturbed surficial units immediately below the lens is further evidence that the lens basalt is extrusive and that it buried surficial units.

New Ar40/Ar39 dating indicates an age of 6.98 ± 0.18 Ma for the lens basalt. A topographically, but not necessarily stratigraphically, higher basalt unit located 1 km ENE of the lens was dated at 7.35 ± 0.19 Ma (Auerbach, 2004). A basalt from the monocline beneath the lens has an age of 7.62 ± 0.32 Ma (Ackerly, 2004).

The Hjallin Lens thus appears to be a thick, homogenous extrusive. Its thickness could be due to its unique position immediately adjacent to a large monoclinal fold structure (Ackerly, 2004). Extension-related down-dropping, perhaps reinforced by crustal loading from accumulating lavas, resulted in the creation of the monocline and the formation of a topographic low. As it erupted, the lava flowed down into this valley, where it pooled and subsequently crystallized rapidly.

Purely periodic triangle sequences correspond to cubic irrationals alpha and beta. We will show a variety of methods for finding the irreducible cubic polynomials corresponding to both alpha and beta. Finally, we will explore some of the interesting polynomials which emerge from the sequences that are purely periodic of periodicity length one.

The goal of my thesis is to find a presentation for the fundamental group of projective spherical Coxeter complexes with minimal blow-ups. It is based on work by Davis, Januszkiewicz and Scott (DJS), who prove that the fundamental group is the kernel of a map p from a group OW that acts on the universal cover of the space onto the underlying group W. DJS prove this result for abstract systems, and thus translating their work is non-trivial, in fact very difficult. We translate their work into the language of graph-associahedra developed by the SMALL 2004 configuration spaces group and specifically compute OW and p. Given these computations, we calculate the fundamental group of these spaces (through dimension six) using java code and a computational algebra package called GAP. From these results, we develop a conjecture for the first homology group.

This thesis is the near completion of work done by the 2001-2003 Geometry Groups to prove the double bubble conjecture in the three-sphere S3 and hyperbolic three-space H3 in the cases where we can apply Hutchings theory:

• in S3, both enclosed volumes and the complement occupy at least 10% of the volume of S3

• in H3, the smaller volume is at least 85% that of the larger

and in Gauss space Gm for three-equal-volume double bubbles. A balancing argument and asymptotic analysis reduce the problem in S3 and H3 to some computer checking. The computer analysis has been designed and fully implemented in S3. In H3, it has been only partially implemented.

Let (T,M) be a complete local ring such that |T/M| = |T|. Given a finite set of incomparable non-maximal prime ideals C of T, we provide necessary and sufficient conditions for T to be the completion of a local UFD A with semi-local generic formal fiber with maximal ideals the elements of C. We also prove an extension of this result where A contains a height one prime ideal with semi-local formal fiber with maximal ideals the elements of C. In addition, we discuss the possibility of forcing our UFD A to be excellent.

Using the theory of continued fractions, we produce a new sharp Diophantine inequality involving an irrational number and a rational approximation to that number, such that the only solutions are precisely all the “best rational approximates” to the given irrational number; that is, the complete list of its convergents. This work generalizes and extends previously known results appearing in the literature. We also identify the best rational approximates when simultaneously approximating a finite number of generalized golden ratios in the same quadratic field.

In this paper, we examine the implications of rotating linkages in generalized norms. We prove that fully rotating a rhombus with both diagonals implies that the norm is linearly equivalent to Euclidean or that the triangle has a certain exceptional property. We also demonstrate that the same is implied by full rotation of some non-exceptional isosceles triangle with median or right triangle with median. In addition, we prove that all triangles can be fully rotated in any norm, and that that rotation is continuous if the norm is strictly convex.

A rich class of hyperbolic 3-manifolds can be represented as the complement of a knot or link in a closed orientable 3-manifold. For these cusped manifolds, we are interested in finding totally geodesic Seifert surfaces, surfaces whose boundary is the knot or link. We consider knot complements for knots embedded in Euclidean 3-manifolds, spherical 3-manifolds, and S2 x S1. We show that all of the closed Euclidean 3-manifolds contain a hyperbolic knot with totally geodesic Seifert surface. Additionally, we show that S2 x S1 and all lens spaces L(p,q) contain a hyperbolic knot with totally geodesic Seifert surface. Also, we give examples of some immersed totally geodesic surfaces in knot complements in the 3-sphere.

Two generalizations of the Minkowski ?(x) function are given. As ?(x) maps quadratic irrationals to rational numbers, it is shown that both generalizations send natural classes of pairs of cubic irrational numbers in the same cubic number field to pairs of rational numbers. It is also shown that these functions satisfy an analog to the fact that ?(x), while continuous and increasing, has derivative zero almost everywhere. Both extend earlier work of Beaver-Garrity on the Farey-Bary map.

The Berlin Wind Project is a Williams College-sponsored study of the potential for electricity generation by a 7-9-turbine wind farm at Berlin Pass (Berlin, NY). Two questions must be addressed in assessing the project’s viability. (1) How much energy could the proposed wind farm produce in a year? (2) What would be the turbines’ visual impact? In this thesis, I present both the answers to these questions and the techniques necessary to obtain them.

I first conclude that AWS Truewind’s wind resource maps predict energy yield with an accuracy of approximately 16±3% in the northern Berkshire/Taconic region, and that the maps also predict directional distributions quite reasonably. I next conclude that a 7-turbine wind farm at Berlin Pass could produce 35±4% million kW-hr per year, or 163±21% of Williams College’s 2002-2003 energy use on average. Because of natural fluctuations in wind speed, this value could vary by as much as an additional ±10% from year to year. Furthermore, since the prevailing winds at the Pass blow from the WNW and the ridgeline runs NNE-SSW, turbine shading should not cause substantial energy losses—though there would likely be some losses from a moderate SSW wind component. (Assuming a net turbine cost (sale price + installation) of $1.24 million ($8.65 million for 7 turbines) and an average wholesale electricity price of $38/MW-hr the farm could pay for itself in 6.5±.84 years ignoring the time value of money.

In addition, based on the results of the visual impact study—some 59 potential views of the wind farm from various locations within a 20 km radius of the Pass—I conclude that the turbines are likely to be visible from quite a few locations throughout the region. However, from a number of these locations the turbines may appear to be quite small and could remain unnoticed by all but the most careful observers.

In light of these results, my recommendation to the College is to continue researching the Project while maintaining an open dialog with the local communities.

This thesis presents program towards measurements of the 7S1/2 -> 7P1/2 E1 transition in atomic thallium. Since the ground state of thallium’s valence electron is the 6P1/2 state, the 6P1/27 ->S1/2 transition must also be driven. The feasibility of such a two-step excitation using present equipment will be demonstrated. Measurements will initially be made in a vapor cell environment, and they will lead up to a measurement of the Stark shift in an atomic beam environment. High-precision measurements such as this will provide valuable information regarding atomic wave functions and electroweak theory, which will help to refine the Standard Model.

Successful operation of a pulsed erbium-ytterbium co-doped all-fiber laser is reported. The laser is capable of lasing at 1.55 µm using a 1.06 µm Nd: YAG laser pump source. The employment of a polarization sensitive nonlinear-optical loop mirror (NOLM) has led to passive mode-locking. Pulses trains lasting on the order of hours have been achieved. Interpretation of pulse spectra and autocorrelations has shown these pulses to be approximately 1-2 picoseconds in duration. A new model of the NOLM has been formulated incorporating fiber birefringence and polarization. This model suggests a technique for exploiting birefringence in the fiber to shift the switching threshold of the NOLM.

Traditional bioinformatics methods scan primary sequences for patterns. In cases such as RNA splicing or editing, however, cellular action may depend in some way on the RNA’s secondary structure. If the information content of the primary sequence is small, how accurate can primary sequence methods be? We study the problem of donor pre-mRNA splicing, where the dataset is sufficiently large that the sequence overlaps between real and decoy sequences, which limit the performance of primary sequence methods, can be quantified. We propose a model that with sufficient training approaches the optimal accuracy permitted by primary sequence analyses, and we assess the accuracy of a class of primary sequence methods generally by studying how they scale with dataset size.

Though quantum-confined semiconductors have been studied at length and are currently used in some applications of opto-electronics, little is known about the effect of quantum confinement on their ultrafast dynamics. In this thesis, we continue previous work in the Bolton lab that established models and materials choices for this work. We analyze four-wave mixing observations of the ultrafast exciton dynamics in In0.04Ga0.96As quantum wells. When compared across a range of well widths that span the transition from two- to three-dimensional excitons, these data show that increasing exciton confinement dampens their interactions with one another and with phonons significantly. In the future, these data will be combined with pump-probe spectroscopy techniques to further quantify the results.

The continuous Wigner function provides a way of representing the quantum states of systems with continuous degrees of freedom. As not all systems have continuous degrees of freedom, Wigner functions have also been developed for discrete quantum systems. There are many different discrete Wigner functions for a system with N orthogonal states. One popular version is defined on a 2N x 2N discrete phase space, whereas the one we use in this thesis is defined on a N x N discrete phase space. Another feature of our discrete Wigner function is that the field of real numbers that labels the axes of continuous phase space is replaced by a finite field having N elements. There exists such a field if and only if N is a power of a prime; so our formulation can be applied directly only to systems for which the state-space dimension takes such a value. While this constraint appears limiting, we note that any quantum computer based on qubits meets the condition and can thus be represented using our Wigner function. In this thesis, we present our description of the discrete Wigner function and look at a number of questions that arise from this construction. First, there are a number of different ways to define the Wigner function for a given N, but how many of these are actually fundamentally different? We define and prove some things about a notion of similarity for any value of N, and then we present a method for calculating the number of similarity classes. Another question is: "What happens when you apply a unitary transformation to the Wigner function?" We develop a method for analyzing the effect of such a transformation and use it to look at a two-qubit version of Grover’s search algorithm.

The production of a Bose Einstein condensate (BEC) in dilute gases requires extremely low temperatures and high density. This thesis describes progress on the laser systems required to cool and confine RB-87 atoms to their Bose-condensed phase. It includes work on the magneto-optical trap, which uses a magnetic field and 780nm diode lasers, and the far-detuned dipole trap, which uses a 100W carbon dioxide laser focused to a spot roughly 40µm.

Ischemic events such as cardiac arrest and stroke affect over a million people in the United States every year. Cognitive deficits following such events are often associated with damage to the hippocampus. Using animal and cell culture models, estradiol administration has been shown to protect the hippocampus from such damage. Furthermore, in male rats it has been shown in that estrogen-mediated neuroprotection from ischemic injury can be demonstrated in behavioral models of learning and memory dependent on the hippocampus. The present study examined whether this behavioral neuroprotection is dependent on sex or the level of estradiol using a 2x3x2 design [(Sex: Male and Female) x (Hormone: Placebo, Low Estradiol (.25mg/pellet), High Estradiol (2.5mg/pellet)) x (Surgery: Ischemia and Sham)]. Gonadectomized male and female rats were implanted with 21-day time-release hormone pellets on PND 35 and experienced transient global ischemia via four-vessel occlusion or a sham surgery two weeks later. A week following surgical procedures, all rats were tested on a non-hippocampally dependent visible platform Morris Water Maze (MWM) variant and then on the hippocampally dependent hidden platform MWM. Blood samples were obtained via cardiac puncture to determine plasma estradiol levels on the day of ischemia. Estradiol levels were quantified using radioimmunoassay (RIA). No sex differences were observed in either the visible or hidden platform tasks. Subjects treated with high estradiol performed significantly worse than those pretreated with placebo capsules on the visible platform task. Sham subjects receiving high estradiol performed significantly worse than subjects receiving low estradiol on the MWM. However, this result was reversed in ischemic subjects, with high estradiol subjects outperforming subjects from the low estradiol group. These findings suggest a differential dose-dependent response in performance on the MWM in ischemic and non-ischemic animals.

Individuals make frequent errors when it comes to determining how they appear in the eyes of others. Specifically, individuals tend to misestimate how others will judge them on the basis of their behavior or performance, often expecting to be judged more harshly than they actually are. This thesis explores one reason for this phenomenon: individuals’ tendency to project their own awareness of context information onto observers. Individuals tend to evaluate their own performance based on certain contextual information (e.g., comparisons with their own past performances, with others, or with ideal standards) that may not be known to observers. In three studies, I show that individuals tend to expect observers to judge them in light of such context information even when they know that observers are not aware of it. In other words, individuals expect observers to make a comparative judgment of them and their performance, rather than an absolute one, even when the standard of comparison is private and is available only to the individuals themselves. Based upon this research, I conclude that when actors have a salient standard of comparison against which to judge their own performance that is unknown to observers, there will tend to be a divergence between how actors are judged and how they expect to be judged.

Twenty-six children took part in a longitudinal study of symbolic thought. At time2 (age 36 months), children were tested in four domains related to symbolic functions: completing pretend narratives, performance on a model room task (representational thought), language comprehension, and fantasy proneness. The narrative completion task measured children’s ability to engage in and provide endings to pretend narratives that were presented to them. The representational task investigated the children’s ability to understand that an object can stand for another. Language comprehension was measured using the third edition of the Peabody Picture Vocabulary Test, and fantasy proneness was assessed through mothers’ reports of their children’s play activities. Some of these domains were positively correlated to each other, although only the correlation between the performance on the narrative completion task and the score on the fantasy proneness measure was significant. At time1 (age range from 25 to 30 months, M = 28 months), children were assessed on four related dimensions of symbolic thought. After analyzing the longitudinal relationships between time1 and time2, the principal conclusion is that children who are prone towards fantasy-oriented activities and engage frequently in pretend play perform well on independent measures of representational thinking (e.g., model room task) and on a measure of narrative construction.

Studies on the behavioral effects of iron deficiency (ID) have focused on the postnatal or adult periods. In addition, little attention has been paid to ID effects on affective behavior although alterations in the relevant neurotransmitter system, GABA, have been documented. In this experiment, two measures of anxiety, ultrasonic vocalizations (USV) and elevated plus maze (EPM) were used to investigate the consequences of maternal ID. Female Long-Evans rats were assigned randomly to one of three diet groups: low iron (10-20ppm Fe), standard (60ppm Fe) or lab chow (250ppm Fe) diet. Diets started seven days prior to mating and continued until ten days after birth (PN10), after which all dams were iron replete with the lab chow diet. USVs after maternal separation was used to test for anxiety in neonates and EPM was used for adults. Maternal behavior, growth, and activity were also assessed. Blood samples taken from pups on PN10 revealed a significant decrement in serum iron and a compensatory increase in total iron binding capacity in the low iron groups compared to the control groups. Relative to the two control groups, the low iron group weighed less on PN1, and this weight difference persisted in adulthood. In neonates, the rate of USVs in the low iron group was significantly higher than the two control groups, and their general activity was significantly less than the controls’. Maternal behavior was not significantly different across groups. By adulthood, anxiety behavior and motor activity in the low iron group were comparable to controls. This study shows that prenatal deficiency results in anxiety behavior, low weight and decreased activity. These deficits, except for weight, were reversed with iron repletion. Future research is needed to elucidate the mechanism of ID effects on anxiety and the persistent weight deficit.

While the role that attributions play in marital relationships has been studied extensively there is very little research on the role of attributions in parent-teen relationships. The studies conducted on parental attributions often concern parents of young children and generally do not include fathers or teenagers. Two studies addressed causal attributions and their relationship to conflict and teen adjustment. Study 1 included 60 mothers and 21 fathers and assessed the relationship between internal, stable, global, and responsibility attributions regarding 11 hypothetical negative teen behaviors, and conflict and teen adjustment. This study also included two exploratory questions concerning the relationship between these attributions and the age of the teen and the relationship between parental responses to negative behavior and causal attributions. A multiple regression with internality, stability, globality, and responsibility as predictor variables, regressed on conflict, was significant. The results also indicated that the globality of parental attributions was a significant predictor of both conflict and teen adjustment. Study 2 included 27 teenagers, 22 mothers, and 8 fathers and elicited participants’ articulated thoughts concerning two audiotaped parent-teen conflicts using Davison, Robins and Marcia’s (1983) Articulated Thoughts in Simulated Situations paradigm. Teens’ reports of conflict was negatively correlated to the frequency of perspective taking and positively correlated to the frequency of automatic thoughts. Parents and teens did not make stable or global attributions during the ATSS procedure. In addition, affective responses during the conflicts and the exploratory topic of the tipping point were examined. Finally, the limitations and implications of both studies are discussed and possibilities for future studies are explored.

In this study, sociometric interviews were conducted to determine children’s actual and perceived social status in the classroom. On the basis of these scores, five groups of children (Overestimators, Underestimators, High Accurates, Low Accurates, and Averages) were identified and recruited to participate in an experimental paradigm designed to measure aggressive responding to positive or negative feedback. Based on Bushman and Baumeister’s (1998) work, we expected those children who overestimated their social status to respond most aggressively to negative feedback. We also expected that they would positively distort negative feedback in predictable ways. Finally, we expected Overestimators to report the lowest frequency of internalizing problems on self-report measures, but to receive higher ratings for externalizing problems according to parent- and peer-report. Contrary to expectations, Overestimators did not respond most aggressively in the experimental paradigm; rather it was the Underestimators who responded more aggressively than any other group. In addition, Overestimators did not distort the negative feedback they received. However, with regard to broader indices of adjustment, Overestimators and Low Accurates were rated as most aggressive by their peers. Overestimators also reported fewer depressive symptoms and higher scores on self-perceived conduct than three of the other groups.