Pbody: A parallel N-body library

Blackston, David Thomas University of California, Berkeley 2000 해외박사(DDOD)

In this thesis we present the Pbody library, a portable parallel adaptive <italic> N</italic>-body solver. We show how three of the better known treecodes in existence (the Barnes-Hut method, Anderson's method, and the Fast Multipole Method) are similar enough in structure to be able to be incorporated into a single unified library. Full descriptions of the sequential versions of these algorithms are provided. We describe how these treecodes may be expressed in terms of supersteps in the Bulk Synchronous Parallel model of computation and shows that this leads to parallel codes that are very similar in structure to the single processor versions of the code. This exposition highlights the primary code innovation of this research, the generalization of the local essential tree to something suitable for <italic>O</italic>(<italic>N</italic>) methods. We describe how this generalized tree may be determined in a sender driven manner. This thesis shows how the Pbody library overcomes some of the difficulties inherent in the parallelization of a complicated algorithm, namely, ensuring that the parallel computation is correct and reasonably well load balanced. We describe the two load balancing schemes incorporated with the Pbody library, the methods of Orthogonal Recursive Bisection and CostZones. We demonstrate the accuracy of the library for a variety of setting on a variety of input distributions. In so doing, we provide a scheme for choosing the best settings of the library for a given input distribution. We show that the library provides good parallel performance for the two load balancing schemes included with the library, and point out ways in which this performance could be improved in the future. Finally, we show that the performance the Pbody library is comparable to another popular treecode by providing a case study of the integration of the Pbody library into the EBEAM electron beam simulation application. For this application, the Pbody library allowed for a substantial performance increase over the initial multipole code chosen for the application.

Hydrogen sulfide induced suspended animation

Blackstone, Eric A University of Washington 2006 해외박사(DDOD)

My graduate career has taken me from inquiring about the roles of endosymbionts in sympatric speciation, through genes required for worms to enter into suspended animation, to a mammalian model for treating a variety of hypoxia/ischemia-based diseases. The work described here demonstrates that concepts learned in one model system (worms) can be successfully applied to other systems (mice) and also reveals the possibilities of discovering benefit by studying a phenomenon. Specifically, suspension was previously known to be inducible in worms via a change in their environment (removal of oxygen) and, by analyzing the physiological aspects of mammalian hibernators, altered environments (addition of low levels of H2S) put mice into a hibernation-like suspended state. This suspended state is characterized by a ten-fold drop in metabolic rate, which is followed by a drop in core body temperature to within ∼2°C of the ambient temperature. Not only does H2S induce a suspended state, there is benefit for these mice, compared to their active counterparts, in their ability to survive otherwise lethal hypoxia. Mice pretreated with H 2S can survive over six hours in 5% oxygen (compared to the ∼15 minute survival time for untreated controls) and survival is possible at oxygen tensions as low as 3%. The broad, whole organism approach demonstrated here has provided a potentially broad, widely applicable solution to a variety of medically relevant problems involving insufficient oxygen within the body.

Precision measurements of deuteron photodisintegration using linearly polarized photons of 14 and 16 MeV

Blackston, Matthew Duke University 2007 해외박사(DDOD)

A precision measurement of the d( g&ar; ,n)p reaction was performed at the High Intensity gamma-ray Source (HIgammaS), which is located at the Duke Free Electron Laser Laboratory on the campus of Duke University. The gamma-ray beams were nearly 100% linearly polarized, allowing the angular distributions of both the analyzing power and unpolarized cross section to be measured at 14 and 16 MeV. The photons were incident on a heavy water target and the neutrons from the photodisintegration reaction were detected using the Blowfish detector array, which consists of 88 liquid scintillator detectors with large angular coverage. A transition matrix element (TME) analysis was performed on the data which allowed the amplitudes of the TMEs which contribute to the reaction at these energies to be extracted. This was done by invoking Watson's theorem, which fixes the relative TME phases using the n-p scattering phase shifts, leaving the TME amplitudes as free parameters in fits to the data. The results indicated very good agreement with a recent potential model calculation for the amplitudes of the three electric dipole (E1) p-waves, which account for over 90% of the cross section at these energies. The extracted TME amplitudes were then used to construct the observable which enters into the Gerasimov-Drell-Hearn (GDH) sum rule integrand. The results are the first experimental indication of a positive value of the GDH integrand in the region near photodisintegration threshold. A positive value at these energies has been shown by theory to be due to relativistic contributions.

Racing for the cure and taking back the night: Constructing gender, politics, and public participation in women's activist/volunteer work

Blackstone, Amy Maria University of Minnesota 2003 해외박사(DDOD)

Gender ideologies are an important yet understudied feature shaping social change in America. In the following dissertation project, I analyze the social processes through which gender is constructed and reproduced in the U.S. breast cancer movement in comparison to those in the anti-sexual violence movement. Though prior sociological research finds that gender matters to social movements and activism, this research builds from the identification of gender as important to show <italic>how</italic> gender matters. Findings are based on over three years of ethnographic research, a period during which I conducted on-going participant observation at two social movement organizations and three activist/advocacy conferences. In addition to my intensive participation at these locations, I completed formal and informal interviews with over sixty social movement participants and analyze movement brochures, flyers, photographs, news articles, and other memorabilia collected during my years of participation. My analysis reveals contradictions as an inherent feature of social movements, social movement organizations, and participation within movements. In the chapters that follow, I analyze the causes and consequences of these contradictions. Specifically, I show that gendered constructions of social change shape the extent to which women are thought of, and think of themselves, as political actors and as fully participating members of society. I also find that narrow conceptions of politics keep women's activist and volunteer efforts invisible—out of view from those with whom such groups might form alliances, out of view from potential beneficiaries of women's activist and volunteer efforts, and out of view from critics who argue that Americans' concern for others has disappeared. This work contributes to literatures in the sociology of gender, social movements, and public and political participation.

Using Blinking to Mitigate Passive Side Channel Attacks and Fault Attacks

Blackstone, Jeremy ProQuest Dissertations & Theses University of Cali 2021 해외박사(DDOD)

A Metacognition-Based Approach to Improve HIV-associated Neurocognitive Disorders among Substance Users

Casaletto, Kaitlin Blackstone ProQuest Dissertations & Theses University of Cali 2016 해외박사(DDOD)

Rationale: The neurotoxic effects of comorbid HIV infection and substance use disorders (HIV/SUD) preferentially impact the fronto-striatal regions of the brain, leading to increased disruption of higher-order executive functions. Poor insight into such neurocognitive deficits (impaired metacognition) tracks with executive dysfunction and is associated with errors in everyday life. We evaluated the efficacy of a brief Metacognitive Training module for neurorehabilitation of HIV/SUD individuals. Design: A between-subjects, randomized design was used to examine the effectiveness of Metacognitive Training among HIV/SUD individuals with current executive dysfunction. To determine the efficacy of the Metacognitive Training compared to an executive strategy (Goal Management Training, GMT), 90 HIV/SUD participants were randomized to: 1) active control (n=30); 2) executive strategy only (i.e., GMT; n=30); or 3) Metacognitive Training plus executive strategy (Meta+GMT; n=30). Following the study condition, participants completed a complex instrumental activities of daily living (IADL) task (Everyday Multitasking Test, "Everyday MT"); additionally, in-vivo metacognitive abilities regarding IADL task performance were evaluated. Results: There was an increasing tendency for better Everyday MT performances across study conditions (Control≤GMT≤Meta+GMT) that approached significance (ps<0.08). Pairwise differences indicated the GMT or Meta+GMT trainings demonstrated small (d=0.20-0.24) benefits in Everyday MT performance compared to the control condition (ps<0.11). HIV/SUD individuals who completed the GMT (in addition to the Meta or not) had significant, medium-sized enhancements in Everyday MT performances compared the control condition (ps<0.05; ds=0.38-0.41); the effect of these enhancements became even larger among those who had poorer dual-tasking capacities prior to training and completed the GMT (ps<0.04; ds=0.83-1.04). Regarding metacognition, although there was no significant study group effect on Global Metacognition, Online Awareness (one of the two components of global abilities) showed a significant positive trend across training condition (Control≤GMT≤Meta+GMT; p=0.04). Among the skills comprising Online Awareness, a tendency toward more elaborate Task Appraisals was observed among HIV/SUD individuals who completed either the GMT or Meta+GMT (versus control; ps<0.07, ds=0.21-0.27). Those who completed the GMT (in addition to the Meta or alone) demonstrated medium, significant benefits of GMT on Task Appraisals compared to the control condition (p=0.01; d=0.50). Conclusions: Our experimental design demonstrated meaningful benefits of a brief GMT executive strategy for everyday multitasking and metacognition among HIV/SUD individuals. Ours are among the first findings supporting a compensatory neurorehabilitation tool in HIV+ individuals and/or substance users.

The impact of outpatient prescription drug coverage on total and specific health care expenditure and service use of Medicare beneficiaries, age sixty-five and older

Artz, Margaret Blackstone University of Minnesota 2000 해외박사(DDOD)

This research was a non-experimental, retrospective, cross-sectional, and descriptive cohort study of eligible persons, 65 years of age and older who participated in the 1992 through 1995 Medicare Current Beneficiary Survey (MCBS). The purpose was to determine the impact of outpatient prescription drug coverage on total and/or specific health care expenditure and service use of Medicare beneficiaries using data present in the MCBS Cost-and-Use data files. Specific aims examined the association between insurance coverage (Medicare, Medicare HMO, Private, Private + HMO), outpatient prescription drug coverage (no, yes), and level of generosity of prescription coverage (none, poor, fair, good) to expenditures/use. Yearly specific expenditure (dollars) and use (number of events) included Medicare-covered and non Medicare-covered services. <italic>Results</italic>. Outpatient prescription drug coverage (yes/no) was associated with increased prescription expenditure/events. As for the effect of the prescription drug coverage generosity on health care expenditure and use, the following observations were seen in the Private insurance group. <table cwl="91:91:92:91:88:62" wdm="100" dispwid="8.38in"><rowrule rty="."> <tablerow><cellrule rty="."> <tablecell>Generosity of Rx Coverage Use/Expense</tablecell> <cellrule rty="."> <tablecell>Inpatient Hospital Use/Expense</tablecell> <cellrule rty="."> <tablecell>Outpatient Hospital Use/Expense</tablecell> <cellrule rty="."> <tablecell>Medical Provider Use/Expense</tablecell> <cellrule rty="."> <tablecell>Rx Use/Expense</tablecell> <cellrule rty="."> <tablecell>Total Expense</tablecell> <cellrule rty="."></tablerow> <rowrule rty="-"> <tablerow><cellrule rty="."> <tablecell cvj="c">none</tablecell> <cellrule rty="."> <tablecell chj="c" cvj="c">Baseline</tablecell> <cellrule rty="."> <tablecell cvj="c">Baseline</tablecell> <cellrule rty="."> <tablecell chj="c" cvj="c">Baseline</tablecell> <cellrule rty="."> <tablecell cvj="c">Baseline</tablecell> <cellrule rty="."> <tablecell cvj="c">Baseline</tablecell> <cellrule rty="."></tablerow> <rowrule rty="."> <tablerow><cellrule rty="."> <tablecell>poor</tablecell> <cellrule rty="."> <tablecell chj="c">+/+</tablecell> <cellrule rty="."> <tablecell>/+</tablecell> <cellrule rty="."> <tablecell chj="c">++/+</tablecell> <cellrule rty="."> <tablecell>++/+</tablecell> <cellrule rty="."> <tablecell chj="r">+</tablecell> <cellrule rty="."></tablerow> <rowrule rty="."> <tablerow><cellrule rty="."> <tablecell>fair</tablecell> <cellrule rty="."> <tablecell chj="c">++/++</tablecell> <cellrule rty="."> <tablecell>/++</tablecell> <cellrule rty="."> <tablecell chj="c">++/++</tablecell> <cellrule rty="."> <tablecell>++/++</tablecell> <cellrule rty="."> <tablecell chj="r">++</tablecell> <cellrule rty="."></tablerow> <rowrule rty="."> <tablerow><cellrule rty="."> <tablecell>good</tablecell> <cellrule rty="."> <tablecell></tablecell> <cellrule rty="."> <tablecell>/+++</tablecell> <cellrule rty="."> <tablecell chj="c">+/+</tablecell> <cellrule rty="."> <tablecell>+/+++</tablecell> <cellrule rty="."> <tablecell chj="r">+++</tablecell> <cellrule rty="."></tablerow> <rowrule rty=".">. (1) all generosity levels of prescription drug coverage were associated with increased total health care expenditures per person per year; the more generous the prescription drug coverage, the greater the expenditure, (2) “poor” and “fair” generosity levels of prescription drug coverage were associated with increased inpatient hospital expenditures and events per person per year, (3) all levels of generosity of prescription drug coverage were associated with increased medical provider with the smallest increases occurring in the “good” level, (4) all levels of generosity of prescription drug coverage were associated with increased prescription expenditures and events per person per year; with evidence of more expensive prescription events per person as generosity level increased. Within the Medicare HMO insurance group, no definitive patterns were seen in any service category except prescription events. All levels of generosity increased prescription events per person per year with the smallest increases occurring in the “good” generosity level.