4,022 research outputs found

    Sixty day manned evaluation of zero gravity humidity control system

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    Manned evaluation of zero gravity humidity control system in potable water recovery unit for simulated spacecraft cabin

    Carbon Monoxide Exposure and Human Health

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    The primary objective of this report is to provide detailed information on the health effects of carbon monoxide. With this information, the community can judge for itself what action is deemed necessary to maintain or improve the health of its residents

    Phase transitions and bubble nucleations for a phi^6 model in curved spacetime

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    Condsidering a massive self-interacting phi ^6 scalar field coupled arbitrarily to a (2+1) dimensional Bianchi type-I spacetime, we evaluate the one-loop effective potential. It is found that phi ^6 potential can be regularized in (2+1) dimensional curved spacetime. A finite expression for the energy-momentum tensor is obtained for this model. Evaluating the finite temperature effective potential, the temperature dependence of phase transitions is studied. The crucial dependence of the phase transitions on the spacetime curvature and on the coupling to gravity are also verified. We also discuss the nucleation of bubbles in a phi ^6 model. It is found that there exists an exact solution for the damped motion of the bubble in the thin wall regime.Comment: 15 pages, 6 figure

    Racial categories in machine learning

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    Controversies around race and machine learning have sparked debate among computer scientists over how to design machine learning systems that guarantee fairness. These debates rarely engage with how racial identity is embedded in our social experience, making for sociological and psychological complexity. This complexity challenges the paradigm of considering fairness to be a formal property of supervised learning with respect to protected personal attributes. Racial identity is not simply a personal subjective quality. For people labeled "Black" it is an ascribed political category that has consequences for social differentiation embedded in systemic patterns of social inequality achieved through both social and spatial segregation. In the United States, racial classification can best be understood as a system of inherently unequal status categories that places whites as the most privileged category while signifying the Negro/black category as stigmatized. Social stigma is reinforced through the unequal distribution of societal rewards and goods along racial lines that is reinforced by state, corporate, and civic institutions and practices. This creates a dilemma for society and designers: be blind to racial group disparities and thereby reify racialized social inequality by no longer measuring systemic inequality, or be conscious of racial categories in a way that itself reifies race. We propose a third option. By preceding group fairness interventions with unsupervised learning to dynamically detect patterns of segregation, machine learning systems can mitigate the root cause of social disparities, social segregation and stratification, without further anchoring status categories of disadvantage

    Acoustic Modal Patterns and Striations (AMPS) experiment G-325, Norfolk Public Schools

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    This paper will describe how high school students with the guidance of volunteer mentors were able to successfully complete an acoustics space experiment. Some of the NORSTAR program strategies used to effectively accomplish this goal will be discussed. The experiment and present status of results will be explained

    An Examination of the Efficacy of Non-traditional Admissions Criteria on Persistence to Graduation Among Radiography Students

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    The relationship between non-traditional (a.k.a. non- cognitive) admissions criteria and graduation rates of radiography students was investigated. The population for this study included all radiography program directors responsible for accredited programs in the United States and Puerto Rico (N = 618). All programs are required to maintain records on retention in accordance with the Joint Review Committee on Education in Radiologic Technology (JRCERT) (n.d.). A total of 737 radiography programs are recognized by the American Registry of Radiologic Technologists (ARRT) and of the 737 programs, 618 are programmatically accredited by the JRCERT. Of the 618 programs accredited, the institutions offer either an associate’s degree, a bachelor’s degree, or are considered certificate programs. Two-year programs that utilized non-traditional admissions criteria had higher graduation rates. Ad- mission criteria such as the use of prerequisite courses were positively related to student persistence to program completion, while criteria such as departmental observations were not. These conclusions were drawn from data submitted by program directors that en- compassed two- and four-year radiography programs. An ANOVA demonstrated statistically significant differences (p = .05) between two-year programs that employ non-traditional admissions criteria and programs that rely more exclusively on traditional selection criteria such as GPA, standardized tests, reference letters, and interviews. Radiography program directors should be using prerequisite course performance to reformat their current admissions process to improve graduation rates in their programs

    Scoliosis treatment using spinal manipulation and the Pettibon Weighting Systemâ„¢: a summary of 3 atypical presentations

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    BACKGROUND: Given the relative lack of treatment options for mild to moderate scoliosis, when the Cobb angle measurements fall below the 25–30° range, conservative manual therapies for scoliosis treatment have been increasingly investigated in recent years. In this case series, we present 3 specific cases of scoliosis. CASE PRESENTATION: Patient presentation, examination, intervention and outcomes are detailed for each case. The types of scoliosis presented here are left thoracic, idiopathic scoliosis after Harrington rod instrumentation, and a left thoracic scoliosis secondary to Scheuermann's Kyphosis. Each case carries its own clinical significance, in relation to clinical presentation. The first patient presented for chiropractic treatment with a 35° thoracic dextroscoliosis 18 years following Harrington Rod instrumentation and fusion. The second patient presented with a 22° thoracic levoscoliosis and concomitant Scheuermann's Disease. Finally, the third case summarizes the treatment of a patient with a primary 37° idiopathic thoracic levoscoliosis. Each patient was treated with a novel active rehabilitation program for varying lengths of time, including spinal manipulation and a patented external head and body weighting system. Following a course of treatment, consisting of clinic and home care treatments, post-treatment radiographs and examinations were conducted. Improvement in symptoms and daily function was obtained in all 3 cases. Concerning Cobb angle measurements, there was an apparent reduction in Cobb angle of 13°, 8°, and 16° over a maximum of 12 weeks of treatment. CONCLUSION: Although mild to moderate reductions in Cobb angle measurements were achieved in these cases, these improvements may not be related to the symptomatic and functional improvements. The lack of a control also includes the possibility of a placebo effect. However, this study adds to the growing body of literature investigating methods by which mild to moderate cases of scoliosis can be treated conservatively. Further investigation is necessary to determine whether curve reduction and/or manipulation and/or placebo was responsible for the symptomatic and functional improvements noted in these cases

    Security of Tenure and Land Registration in Africa: Literature Review and Synthesis

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    In 1984, the Land Tenure Center embarked on a project to evaluate the experiences with land registration and tenure reform in Africa. The goal was to determine is African states been able to use tenure reform and land registration to provide greater security of tenure than was available through customary tenure systems. Donor agencies focused attention on the creation of individual freehold title, emphasizing the heightened security of holding, marketability, and access to credit under such tenure. National governments, on the other hand, were more concerned to see that land was used productively rather than merely accumulated for purposes of prestige or inheritance or as a hedge against inflation, and for this reason have tended to favor granting more circumscribed rights, such as leaseholds or rights of occupancy. This literature review and synthesis was prepared as part of an effort to increase very substantially our knowledge, especially on a quantitative level, of tenure and development relationships in Africa. The literature review is an attempt to gather in one place data about the diverse efforts at land registration and to describe briefly for each country the various registration programs that have taken place (if any), why they were undertaken, and what subsequent studies of these programs have found. Among other things, it will be seen that the intended benefits, and beneficiaries, of land registration have changed over the century or so since the first systems were put in place. In addition to these variations over time, there are also differences among Anglophone, Francophone, and Lusophone countries, differences that not only influenced the structure of registration systems established during the colonial era, but also continue to inform the kinds of registration systems adopted today.Land Economics/Use,
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