3,468 research outputs found

    Demographic characteristics and opportunistic diseases associated with attrition during preparation for antiretroviral therapy in primary health centres in Kibera, Kenya.

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    Using routine data from HIV-positive adult patients eligible for antiretroviral therapy (ART), we report on routinely collected demographic characteristics and opportunistic diseases associated with pre-ART attrition (deaths and loss to follow-up). Among 2471 ART eligible patients, enrolled between January 2005 and November 2008, 446 (18%) were lost to attrition pre-ART. Adjusted risk factors significantly associated with pre-ART attrition included age <35 years (Odds Ratio, OR 1.4, 95% Confidence Interval, CI 1.1-1.8), severe malnutrition (OR 1.5, 95% CI 1.1-2.0), active pulmonary tuberculosis (OR 1.6, 95% CI 1.1-2.4), severe bacterial infections including severe bacterial pneumonia (OR 1.9, 95% CI 1.2-2.8) and prolonged unexplained fever (>1 month), (OR 2.6, 95% CI 1.3-5.2). This study highlights a number of clinical markers associated with pre-ART attrition that could serve as 'pointers' or screening tools to identify patients who merit fast-tracking onto ART and/or closer clinical attention and follow-up

    Equivariant topological complexity

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    We define and study an equivariant version of Farber's topological complexity for spaces with a given compact group action. This is a special case of the equivariant sectional category of an equivariant map, also defined in this paper. The relationship of these invariants with the equivariant Lusternik-Schnirelmann category is given. Several examples and computations serve to highlight the similarities and differences with the non-equivariant case. We also indicate how the equivariant topological complexity can be used to give estimates of the non-equivariant topological complexity.Comment: v1: 19 pages; v2: 14 pages. Final version, to appear in Algebraic & Geometric Topolog

    A New Approach in Tribological Characterization of High Performance Materials

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    This research conducts tribological investigation in three areas. The first area of research is to obtain basic understanding of tribological properties of high performance Inconel alloys. Pin-on-disk testing was conducted through a range of applied normal loads and sliding velocities in an unlubricated condition. Average friction coefficient, friction work, and specific wear rates were calculated from the data and microscopy techniques were used to observe and characterize wear mechanisms. Experimental results show a dependence of average coefficient of friction as a function of frictional work. Also shown is the wear rate dependence on frictional work, predicated by a wear mechanism change. This research gives a tribological baseline for high performance alloys. The second area of research is in the in situ spatial study of friction, complemented by monitoring changes in electrical contact resistance (ECR). Pin-on-disk testing of samples was done under low normal loads and velocities. Friction and electrical contact resistance measurements were taken spatially in the wear track during each friction cycle, giving a spatial evolution of friction and resistance change, in situ. Results show a lowering in the ECR under increased friction cycles, which was closely related to a change in the friction coefficient of the material. Using surface profilometry and X-ray Photoelectron Spectroscopy, we determined that the lowering of resistance is a result of surface modification through wear and development of a friction induced conductive tribo-film. This research provides a simple method for in situ monitoring of friction and solidifies a fundamental relationship between friction and contact resistance. The third area of research is the design of a variable force tribometer, incorporating the fundamental results demonstrated in the first two experiments. The creation of a novel testing apparatus to test materials under dynamic tribological conditions is given in detail. Simple experiments were performed on an Inconel sample and preliminary results show how dynamic normal and tangential forces affect the friction coefficient. These early results utilizing the variable force tribometer will lay the groundwork for more advanced research into the dynamic nature of friction

    Spatial evolution of friction of a textured wafer surface

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    Abstract Mechanical failure of integrated circuits and micro-electro-mechanical systems (MEMS) demands new understanding of friction in small devices. In present research, we demonstrated an in situ approach to measure sliding friction of a patterned surface composing multi-materials and structures. The effects of materials and surface morphology on friction and electrical contact resistance were investigated. The material transfer at the interface of dissimilar materials was found to play dominating roles in friction. The current work provides important insights from the fundamentals of friction that benefit the design of new micro-devices.</jats:p

    Policy Solutions to Address Mass Shootings

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    In the past decade, mass shootings, particularly those that take place in public areas, have increasingly become part of the national conversation in the United States. Mass public shootings instill widespread fear, in part because of their seeming randomness and unpredictability. Yet when these incidents occur, which has been with somewhat greater frequency and lethality as of late, public calls for policy responses are immediate. In this policy brief, we review efforts to evaluate the effect of gun control measures on mass public shootings, including a discussion of our recently published study on the relationship between state gun laws and the incidence and severity of these shootings. The findings of this work point to gun permits and bans on large-capacity magazines as having promise in reducing (a) mass public shooting rates and (b) mass public shooting victimization, respectively. Interestingly, however, most gun laws that we examined, including assault weapon bans, do not appear to be causally related to the rate of mass public shootings

    SN2013fs and SN2013fr: Exploring the circumstellar-material diversity in Type II supernovae

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    We present photometry and spectroscopy of SN2013fs and SN2013fr in the first 100 days post-explosion. Both objects showed transient, relatively narrow Hα\alpha emission lines characteristic of SNeIIn, but later resembled normal SNeII-P or SNeII-L, indicative of fleeting interaction with circumstellar material (CSM). SN2013fs was discovered within 8hr of explosion. Its light curve exhibits a plateau, with spectra revealing strong CSM interaction at early times. It is a less luminous version of the transitional SNIIn PTF11iqb, further demonstrating a continuum of CSM interaction intensity between SNeII-P and IIn. It requires dense CSM within 6.5×\times1014^{14}~cm of the progenitor, from a phase of advanced pre-SN mass loss shortly before explosion. Spectropolarimetry of SN2013fs shows little continuum polarization, but noticeable line polarization during the plateau phase. SN2013fr morphed from a SNIIn at early times to a SNII-L. After the first epoch its narrow lines probably arose from host-galaxy emission, but the bright, narrow Hα\alpha emission at early times may be intrinsic. As for SN2013fs, this would point to a short-lived phase of strong CSM interaction if proven to be intrinsic, suggesting a continuum between SNeIIn and II-L. It is a low-velocity SNII-L, like SN2009kr but more luminous. SN2013fr also developed an IR excess at later times, due to warm CSM dust that require a more sustained phase of strong pre-SN mass loss.Comment: MNRAS accepted. 28 pages, 23 figures, 8 table

    Carmustine, Etoposide, Cytarabine, and Melphalan (BEAM)–Campath Allogeneic Stem Cell Transplantation for Aggressive Non-Hodgkin Lymphoma: An Analysis of Outcomes from the British Society of Blood and Marrow Transplantation

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    AbstractThe role of allogeneic stem cell transplantation (SCT) in the management of aggressive non-Hodgkin lymphoma (NHL) remains to be defined, but the number of procedures performed continues to increase. We report here the outcomes of allogeneic SCT using carmustine, etoposide, cytarabine, and melphalan (BEAM)-Campath (Genzyme Corporation, Cambridge, MA) conditioning for aggressive NHL as reported to the British Society of Blood and Marrow Transplantation (BSBMT). This retrospective study identified 46 patients who reported to the BSBMT registry as having undergone BEAM-Campath conditioned allogeneic SCT for aggressive NHL between 1999 and 2010. Disease histology was diffuse large B cell lymphoma (DLBCL, n = 25), DLBCL/Burkitt lymphoma (n = 5), and T cell lymphoma (n = 16). At diagnosis, the median age was 42.5 (range, 17 to 59), 37 had advanced stage disease (Ann Arbor III/IV), 28 had 2 or more extra-nodal sites of disease, and 23 had elevated lactate dehydrogenase. International prognostic index was high or high/intermediate in 58%. The median number of prior therapies was 3 (range, 1 to 5) and 5 patients had previously undergone transplantation (4 autologous, 1 allogeneic). The median age at transplantation was 44.8 (range, 18 to 59), with 34 patients demonstrating chemo-sensitive disease and 22 undergoing transplantation in first response. Performance score was good in 40 patients and all engrafted with a median of 14 days (range, 11 to 27) to neutrophil recovery. At latest follow-up, 20 patients were alive with 17 in complete remission. Acute graft-versus-host disease (GVHD) developed in 7 patients and chronic GVHD developed in 13 (7 limited, 6 extensive). Five patients died from nonrelapse causes, with a cumulative incidence of nonrelapse mortality of 7% at 100 days and 11% at 3 and 5 years. Twenty-one patients died after lymphoma relapse, with a cumulative incidence of relapse/progression of 51% at 1 year and 53% at 5 years. Disease status at transplantation had no impact on relapse rate. Progression-free survival was 41% at 1 year and 36% at 5 years. Overall survival was 54% at 1 year and 42% at 5 years. Overall, BEAM-Campath–conditioned allogeneic SCT is well tolerated and able to deliver durable disease-free survival to a subset of patients with aggressive NHL. However, the high relapse rates indicate further investigation is needed to identify those patients most likely to benefit

    Planning Future Strategies for Domestic and International NeuroAIDS Research, July 24–25, 2008

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    The National Institute of Mental Health in cooperation with the National Institute on Drug Abuse and the National Institute of Neurological Disorders and Stroke organized a meeting on July 24–25, 2008 to develop novel research directions for neuroAIDS research. The deliberations of this meeting are outlined in this brief report. Several critical research areas in neuroAIDS were identified as areas of emphasis. Opportunities for collaborations between large NIH-funded projects were also discussed
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