Determination of sediment provenance at drift sites using hydrogen isotopes in lipids

Submitted in partial fulfillment of the requirements for the degree of Master of Science at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2004Paleoclimate records with sufficient length and temporal resolution to study the occurrence and causal mechanisms of abrupt climate change are exceedingly rare. Rapidly deposited ocean sediments provide the best archive for studying these events through geologic time, but such sites in the open ocean are limited to sediment drift deposits such as the Bermuda Rise in the northwest Atlantic. Using multiple climate proxies in a single core is becoming more common in high-resolution paleoclimate investigations, but a major potential concern for this approach arises from the possibility that the fine fraction of sediment (<63 μm), and the climate proxies within it, may represent conditions far from the deposition site. We hypothesize that hydrogen isotope ratios of alkenones, a class of lipids from phytoplankton, may provide insight into the source of fine fraction sediment. Because of their restricted sources, broad geographic distribution, and excellent preservation properties, alkenones are of particular interest in the emerging field of compound-specific hydrogen isotopic analysis, and the sedimentary abundances, extents of unsaturations, and isotopic compositions of alkenones provide quantitative and near-continuous records. We isolated alkenones from cultured unicellular algae (haptophyte Emiliania huxleyi), surface ocean particulate material, and open ocean sediments to determine the extent and variability of hydrogen isotopic fractionation in the di-, tri-, and tetraunsaturated C37 compounds. We then compared the δD of the alkenones in surface sediments between the Bermuda Rise and the Scotian Margin above which a large (~20%) δD gradient exists. We determined the fractionation between alkenones from suspended particulate samples and the water in which the phytoplankton lived, and examined the variability of alkenone δD during key climate transitions at the Bermuda Rise

Determination of sediment provenance at drift sites using hydrogen isotopes in lipids

Thesis (S.M.)--Joint Program in Chemical Oceanography (Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences; and the Woods Hole Oceanographic Institution), 2004.Includes bibliographical references.Paleoclimate records with sufficient length and temporal resolution to study the occurrence and causal mechanisms of abrupt climate change are exceedingly rare. Rapidly deposited ocean sediments provide the best archive for studying these events through geologic time, but such sites in the open ocean are limited to sediment drift deposits such as the Bermuda Rise in the northwest Atlantic. Using multiple climate proxies in a single core is becoming more common in high-resolution paleoclimate investigations, but a major potential concern for this approach arises from the possibility that the fine fraction of sediment (< 63 [micro]m), and the climate proxies within it, may represent conditions far from the deposition site. We hypothesize that hydrogen isotope ratios of alkenones, a class of lipids from phytoplankton, may provide insight into the source of fine fraction sediment. Because of their restricted sources, broad geographic distribution, and excellent preservation properties, alkenones are of particular interest in the emerging field of' compound-specific hydrogen isotopic analysis, and the sedimentary abundances, extents of unsaturations, and isotopic compositions of alkenones provide quantitative and near-continuous records. We isolated alkenones from cultured unicellular algae (haptophyte Emiliania huxleyi), surface ocean particulate material, and open ocean sediments to determine the extent and variability of hydrogen isotopic fractionation in the di-, tri-, and tetraunsaturated C₃₇ compounds. We then compared the [delta]D of the alkenones in surface sediments between the Bermuda Rise and the Scotian Margin above which a large ([approximately]20%) [delta]D gradient exists. We determined the fractionation between alkenones(cont.) from suspended particulate samples and the water in which the phytoplanton lived, and examined the variability of alkenone 6D during key climate transitions at the Bermuda Rise.by Amy C. Englebrecht.S.M

Effect of three-particle correlations in low dimensional Hubbard models

A simple approximation which captures some non-perturbative aspects of the one electron Green function of strongly interacting Fermion systems is developed. It provides a way to go one step beyond the usual dilute limit since particle-particle as well as particle-hole scattering are treated on the same footing. Intermediate states are constrained to contain only one particle-hole excitation besides the incoming particle. The Faddeev equations resulting from an exact treatment of this three-body problem are investigated. In one dimension the method is able to show spin and charge decoupling, but does not reproduce the exact nature of power-law singularities. Hey dudes, check out the analytical solution in section III!Comment: 21 pages plus six figures (appended as postscript files) in RevTeX v.

Securing the Downside Up: Client and Care Factors Associated with Outcomes of Secure Residential Youth Care

Although secure residential care has the potential of reducing young people's behavioral problems, it is often difficult to achieve positive outcomes. Research suggests that there are several common success factors of treatment, of which the client's motivation for treatment and the quality of the therapeutic relationship between clients and therapists might be especially relevant and important in the context of secure residential care. The objective of the present study was to explore the association of these potential success factors with secure residential care outcomes. A repeated measures research design was applied in the study, including a group of adolescents in a secure residential care center that was followed up on three measurements in time. Interviews and questionnaires concerning care outcomes in terms of adolescents' behavior change during care were administered to 22 adolescents and 27 group care workers. Outcomes in terms of adolescents' treatment satisfaction were assessed by the use of questionnaires, which were completed by 51 adolescents. Adolescents reported some positive changes in their treatment motivation, but those who were more likely to be motivated at admission were also more likely to deteriorate in treatment motivation from admission to departure. Treatment satisfaction was associated with better treatment motivation at admission and with a positive adolescent-group care worker relationship. The results suggest that outcomes can be improved by a more explicit treatment focus on improving the adolescent's treatment motivation and the quality of the adolescent-care worker relationship during secure residential care

The Effect of Gender, Political Affiliation, and Family Composition on Reasonable Compensation Decisions: An Empirical Assist

Georgia Southern University faculty member William Brian Dowis co-authored The Effect of Gender, Political Affiliation, and Family Composition on Reasonable Compensation Decisions: An Empirical Assist alongside non-faculty member Ted D. Englebrecht in Advances in Taxation. Book Summary: Volume 25 features eight articles. In the lead article, Savannah Guo, Sabrina Chi, and Kirsten Cook examine short selling as one external determinant of corporate tax avoidance and find that short interest is negatively associated with subsequent tax-avoidance levels and this effect is incremental to other factors identified by prior research. Next, Mark Bauman and Cathalene Rogers Bowler examine the effect of FIN48 on earnings management activity, by focusing on changes in the deferred tax asset valuation allowance. In the third article, Anthony Billings, Cheol Lee, and Jaegul Lee study whether the lowering of dividend taxes as part of the U.S. Jobs and Growth Tax Relief Reconciliation Act of 2003 resulted in an increase in dividend payouts at the expense of R&D spending. The fourth article by Brian Dowis and Ted Englebrecht examines reasonable compensation in closely-held corporations and the impact of gender, political affiliation, and family makeup on decisions made in the U.S. Tax Court. Then, a practice-related study by Sonja Pippin, Jeffrey Wong, and Richard Mason reports on a survey of Americans living abroad on the impact of tax rules explicitly designed for these individuals. They find that Americans living abroad experience the Foreign Account Tax Compliance Act as negatively impacting their lives. The next three articles in this volume have an international focus. Zakir Akhand investigates the effects of the corporate sector on the effectiveness of selected tax compliance instruments in the context of large Bangladesh corporate taxpayers. K-Rine Chong and Murugesh Arunachalam examine the determinants of enforced tax compliance behaviour of Malaysian citizens with trust in the tax agency assumed to be a mediating variable. Lastly, Bitzenis and Vasileios investigate the effect of the economic downturn in Greece on the factors determining the level of tax morale through primary data from a European Union funded research project on the Greek shadow economy

Enrolling and Engaging High-Risk Youths and Families in Community-Based, Brief Intervention Services

Increasing interest has been shown in brief interventions for troubled persons, including those with substance abuse problems. Most of the published literature on this topic has focused on adults, and on the efficacy of these interventions. Few of these studies have examined the critical issues of enrollment and engagement in brief intervention services. The present article seeks to address the shortcomings in the current literature by reporting on our experiences implementing National Institute on Drug Abuse (NIDA)-funded brief intervention projects involving truant and diversion program youths