221 research outputs found
Geometric analysis of satellite laser ranging data
The analysis of simultaneous laser data is investigated using the method of trilateration. Analysis of data from 1987 to 1992 is presented with selected baseline rates and station positions. The use of simultaneous Etalon data is simulated to demonstrate the additional global coverage these satellites provide. Trilateration has a great potential for regional deformation studies with monthly LAGEOS American solutions between 3-12 millimeters
Field-Dependent Critical Current in Type-II Superconducting Strips: Combined Effect of Bulk Pinning and Geometrical Edge Barrier
Recent theoretical and experimental research on low-bulk-pinning
superconducting strips has revealed striking dome-like magnetic-field
distributions due to geometrical edge barriers. The observed magnetic-flux
profiles differ strongly from those in strips in which bulk pinning is
dominant. In this paper we theoretically describe the current and field
distributions of a superconducting strip under the combined influence of both a
geometrical edge barrier and bulk pinning at the strip's critical current Ic,
where a longitudinal voltage first appears. We calculate Ic and find its
dependence upon a perpendicular applied magnetic field Ha. The behavior is
governed by a parameter p, defined as the ratio of the bulk-pinning critical
current Ip to the geometrical-barrier critical current Is0. We find that when p
> 2/pi and Ip is field-independent, Ic vs Ha exhibits a plateau for small Ha,
followed by the dependence Ic-Ip ~ 1/Ha in higher magnetic fields.Comment: 4 pages, 2 figures, Fig. 1 revised, submitted to Phys. Rev.
Production properties of low-mass systems in pp collisions at 102 GeV/c
We examine in detail the properties of low-mass systems produced in the inclusive reaction p + p --> p + anything at 102 GeV/c. We find that the internal characteristics of these low-mass nucleon-multipion systems (the "anything"), at fixed values of mass (M), are similar to those found for produced hadrons in high-energy collisions at fixed incident hadron energies . The resemblance between the properties of the M2 system and the characteristics of [pi]p collisions at s = M2 is particularly striking.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22250/1/0000686.pd
Infusion of Reconstituted High-Density Lipoprotein, CSL112, in Patients With Atherosclerosis: Safety and Pharmacokinetic Results From a Phase 2a Randomized Clinical Trial
Background CSL112 is a new formulation of human apolipoprotein A‐I (apoA‐I) being developed to reduce cardiovascular events following acute coronary syndrome. This phase 2a, randomized, double‐blind, multicenter, dose‐ranging trial represents the first clinical investigation to assess the safety and pharmacokinetics/pharmacodynamics of a CSL112 infusion among patients with stable atherosclerotic disease. Methods and Results Patients were randomized to single ascending doses of CSL112 (1.7, 3.4, or 6.8 g) or placebo, administered over a 2‐hour period. Primary safety assessments consisted of alanine aminotransferase or aspartate aminotransferase elevations \u3e3× upper limits of normal and study drug–related adverse events. Pharmacokinetic/pharmacodynamic assessments included apoA‐I plasma concentration and measures of the ability of serum to promote cholesterol efflux from cells ex vivo. Of 45 patients randomized, 7, 12, and 14 received 1.7‐, 3.4‐, and 6.8‐g CSL112, respectively, and 11 received placebo. There were no clinically significant elevations (\u3e3× upper limit of normal) in alanine aminotransferase or aspartate aminotransferase. Adverse events were nonserious and mild and occurred in 5 (71%), 5 (41%), and 6 (43%) patients in the CSL112 1.7‐, 3.4‐, and 6.8‐g groups, respectively, compared with 3 (27%) placebo patients. The imbalance in adverse events was attributable to vessel puncture/infusion‐site bruising. CSL112 resulted in rapid (Tmax≈2 hours) and dose‐dependent increases in apoA‐I (145% increase in the 6.8‐g group) and total cholesterol efflux (up to 3.1‐fold higher than placebo) (P\u3c0.001). Conclusions CSL112 infusion was well tolerated in patients with stable atherosclerotic disease. CSL112 immediately raised apoA‐I levels and caused a rapid and marked increase in the capacity of serum to efflux cholesterol. This potential novel approach for the treatment of atherosclerosis warrants further investigation. Clinical Trial Registration URL: http://www.ClinicalTrials.gov. Unique identifier: NCT01499420
Laboratory angular distributions for the production of charged secondaries in inelastic proton-proton collisions at 102 GeV/c
Lab angular distributions for the production of charged secondary particles in inelastic proton-proton collisions are presented. Data are separately displayed for protons and for positive and negative mesons (pions and kaons combined).Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22255/1/0000691.pd
Tamm Review: Management of mixed-severity fire regime forests in Oregon, Washington, and Northern California
Increasingly, objectives for forests with moderate- or mixed-severity fire regimes are to restore successionally diverse landscapes that are resistant and resilient to current and future stressors. Maintaining native species and characteristic processes requires this successional diversity, but methods to achieve it are poorly explained in the literature. In the Inland Pacific US, large, old, early seral trees were a key historical feature of many young and old forest successional patches, especially where fires frequently occurred. Large, old trees are naturally fire-tolerant, but today are often threatened by dense understory cohorts that create fuel ladders that alter likely post-fire successional pathways. Reducing these understories can contribute to resistance by creating conditions where canopy trees will survive disturbances and climatic stressors; these survivors are important seed sources, soil protectors, and critical habitat elements. Historical timber harvesting has skewed tree size and age class distributions, created hard edges, and altered native patch sizes. Manipulating these altered forests to promote development of larger patches of older, larger, and more widely-spaced trees with diverse understories will increase landscape resistance to severe fires, and enhance wildlife habitat for underrepresented conditions.
Closed-canopy, multi-layered patches that develop in hot, dry summer environments are vulnerable to droughts, and they increase landscape vulnerability to insect outbreaks and severe wildfires. These same patches provide habitat for species such as the northern spotted owl, which has benefited from increased habitat area. Regional and local planning will be critical for gauging risks, evaluating trade-offs, and restoring dynamics that can support these and other species. The goal will be to manage for heterogeneous landscapes that include variably-sized patches of (1) young, middle-aged, and old, closed canopy forests growing in upper montane, northerly aspect, and valley bottom settings, (2) a similar diversity of open-canopy, fire-tolerant patches growing on ridgetops, southerly aspects, and lower montane settings, and (3) significant montane chaparral and grassland areas. Tools to achieve this goal include managed wildfire, prescribed burning, and variable density thinning at small to large scales. Specifics on ‘‘how much and where?” will vary according to physiographic, topographic and historical templates, and regulatory requirements, and be determined by means of a socio-ecological process
Tamm Review: Management of mixed-severity fire regime forests in Oregon, Washington, and Northern California
Increasingly, objectives for forests with moderate- or mixed-severity fire regimes are to restore successionally diverse landscapes that are resistant and resilient to current and future stressors. Maintaining native species and characteristic processes requires this successional diversity, but methods to achieve it are poorly explained in the literature. In the Inland Pacific US, large, old, early seral trees were a key historical feature of many young and old forest successional patches, especially where fires frequently occurred. Large, old trees are naturally fire-tolerant, but today are often threatened by dense understory cohorts that create fuel ladders that alter likely post-fire successional pathways. Reducing these understories can contribute to resistance by creating conditions where canopy trees will survive disturbances and climatic stressors; these survivors are important seed sources, soil protectors, and critical habitat elements. Historical timber harvesting has skewed tree size and age class distributions, created hard edges, and altered native patch sizes. Manipulating these altered forests to promote development of larger patches of older, larger, and more widely-spaced trees with diverse understories will increase landscape resistance to severe fires, and enhance wildlife habitat for underrepresented conditions.
Closed-canopy, multi-layered patches that develop in hot, dry summer environments are vulnerable to droughts, and they increase landscape vulnerability to insect outbreaks and severe wildfires. These same patches provide habitat for species such as the northern spotted owl, which has benefited from increased habitat area. Regional and local planning will be critical for gauging risks, evaluating trade-offs, and restoring dynamics that can support these and other species. The goal will be to manage for heterogeneous landscapes that include variably-sized patches of (1) young, middle-aged, and old, closed canopy forests growing in upper montane, northerly aspect, and valley bottom settings, (2) a similar diversity of open-canopy, fire-tolerant patches growing on ridgetops, southerly aspects, and lower montane settings, and (3) significant montane chaparral and grassland areas. Tools to achieve this goal include managed wildfire, prescribed burning, and variable density thinning at small to large scales. Specifics on ‘‘how much and where?” will vary according to physiographic, topographic and historical templates, and regulatory requirements, and be determined by means of a socio-ecological process
Associations between the legal context of HIV, perceived social capital, and HIV antiretroviral adherence in North America
Background Human rights approaches to manage HIV and efforts to decriminalize HIV exposure/transmission globally offer hope to persons living with HIV (PLWH). However, among vulnerable populations of PLWH, substantial human rights and structural challenges (disadvantage and injustice that results from everyday practices of a well-intentioned liberal society) must be addressed. These challenges span all ecosocial context levels and in North America (Canada and the United States) can include prosecution for HIV nondisclosure and HIV exposure/transmission. Our aims were to: 1) Determine if there were associations between the social structural factor of criminalization of HIV exposure/transmission, the individual factor of perceived social capital (resources to support one’s life chances and overcome life’s challenges), and HIV antiretroviral therapy (ART) adherence among PLWH and 2) describe the nature of associations between the social structural factor of criminalization of HIV exposure/transmission, the individual factor of perceived social capital, and HIV ART adherence among PLWH. Methods We used ecosocial theory and social epidemiology to guide our study. HIV related criminal law data were obtained from published literature. Perceived social capital and HIV ART adherence data were collected from adult PLWH. Correlation and logistic regression were used to identify and characterize observed associations. Results Among a sample of adult PLWH (n = 1873), significant positive associations were observed between perceived social capital, HIV disclosure required by law, and self-reported HIV ART adherence. We observed that PLWH who have higher levels of perceived social capital and who live in areas where HIV disclosure is required by law reported better average adherence. In contrast, PLWH who live in areas where HIV transmission/exposure is a crime reported lower 30-day medication adherence. Among our North American participants, being of older age, of White or Hispanic ancestry, and having higher perceived social capital, were significant predictors of better HIV ART adherence. Conclusions Treatment approaches offer clear advantages in controlling HIV and reducing HIV transmission at the population level. These advantages, however, will have limited benefit for adherence to treatments without also addressing the social and structural challenges that allow HIV to continue to spread among society’s most vulnerable populations
Genetic association study of QT interval highlights role for calcium signaling pathways in myocardial repolarization.
The QT interval, an electrocardiographic measure reflecting myocardial repolarization, is a heritable trait. QT prolongation is a risk factor for ventricular arrhythmias and sudden cardiac death (SCD) and could indicate the presence of the potentially lethal mendelian long-QT syndrome (LQTS). Using a genome-wide association and replication study in up to 100,000 individuals, we identified 35 common variant loci associated with QT interval that collectively explain ∼8-10% of QT-interval variation and highlight the importance of calcium regulation in myocardial repolarization. Rare variant analysis of 6 new QT interval-associated loci in 298 unrelated probands with LQTS identified coding variants not found in controls but of uncertain causality and therefore requiring validation. Several newly identified loci encode proteins that physically interact with other recognized repolarization proteins. Our integration of common variant association, expression and orthogonal protein-protein interaction screens provides new insights into cardiac electrophysiology and identifies new candidate genes for ventricular arrhythmias, LQTS and SCD
Self-compassion and risk behavior among people living with HIV/AIDS.
Sexual risk behavior and illicit drug use among people living with HIV/AIDS (PLWHA) contribute to poor health and onward transmission of HIV. The aim of this collaborative multi-site nursing research study was to explore the association between self-compassion and risk behaviors in PLWHA. As part of a larger project, nurse researchers in Canada, China, Namibia, Puerto Rico, Thailand and the US enrolled 1211 sexually active PLWHA using convenience sampling. The majority of the sample was male, middle-aged, and from the US. Illicit drug use was strongly associated with sexual risk behavior, but participants with higher self-compassion were less likely to report sexual risk behavior, even in the presence of illicit drug use. Self-compassion may be a novel area for behavioral intervention development for PLWHA
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