1,496 research outputs found
A New Method for Searching for Free Fractional Charge Particles in Bulk Matter
We present a new experimental method for searching for free fractional charge
in bulk matter; this new method derives from the traditional Millikan liquid
drop method, but allows the use of much larger drops, 20 to 100 mm in diameter,
compared to the traditional method that uses drops less than 15 mm in diameter.
These larger drops provide the substantial advantage that it is then much
easier to consistently generate drops containing liquid suspensions of powdered
meteorites and other special minerals. These materials are of great importance
in bulk searches for fractional charge particles that may have been produced in
the early universe.Comment: 17 pages, 5 figures in a singl PDF file (created from WORD Doc.).
Submitted to Review of Scientific Instrument
Immunolocalization and temporal distribution of cytokine expression during the development of vein graft intimal hyperplasia in an experimental model
AbstractPurpose: Vein graft stenosis caused by intimal hyperplasia (IH) accounts for 30% to 50% of late bypass graft failures; however, the biochemical mediators of vein graft IH have been poorly defined. We attempted to evaluate the spatial and temporal distribution of five principal cytokines (interleukin-1 beta [IL-1β], platelet-derived growth factor AA [PDGF-AA], basic fibroblast growth factor [bFGF], interferon gamma [INFγ], and tumor necrosis factor alpha [TNF-α]) during the development of IH in a rat vein graft model.Methods: Rat epigastric vein interposition grafts in the femoral artery were harvested at 6 hours, 2 days, 1 week, 2 weeks, and 4 weeks after the grafting procedure and studied with immunohistochemical and standard histologic techniques. The cytokine expression in the endothelium and media/neointima was quantified as the percentage of immunopositive cells per high-power field.Results: Maximal hyperplasia occurred 2 weeks after the grafting procedure. Peak expression of IL-1β and bFGF occurred by 2 days. PDGF-AA expression paralleled the development of IH, peaking at 2 weeks and then declining. TNF-α expression increased at 1 week and remained elevated. INFγ was seen only in control grafts.Conclusions: The coordinated early release of IL-1β and bFGF and the down-regulation of INFγ seem to trigger an inflammatory response, thereby initiating IH. The process then is propagated by the release of PDGF-AA and TNF-α, with concomitant smooth muscle cell proliferation and production of extracellular matrix. It is likely that this complex milieu of local paracrine signaling is required to generate the hyperplastic response seen in failing vein grafts. (J Vasc Surg 1996;24:463-71.
Integrating Multiple Data Types to Connect Ecological Theory and Data Among Levels
Ecological theories often encompass multiple levels of biological organization, such as genes, individuals, populations, and communities. Despite substantial progress toward ecological theory spanning multiple levels, ecological data rarely are connected in this way. This is unfortunate because different types of ecological data often emerge from the same underlying processes and, therefore, are naturally connected among levels. Here, we describe an approach to integrate data collected at multiple levels (e.g., individuals, populations) in a single statistical analysis. The resulting integrated models make full use of existing data and might strengthen links between statistical ecology and ecological models and theories that span multiple levels of organization. Integrated models are increasingly feasible due to recent advances in computational statistics, which allow fast calculations of multiple likelihoods that depend on complex mechanistic models. We discuss recently developed integrated models and outline a simple application using data on freshwater fishes in south-eastern Australia. Available data on freshwater fishes include population survey data, mark-recapture data, and individual growth trajectories. We use these data to estimate age-specific survival and reproduction from size-structured data, accounting for imperfect detection of individuals. Given that such parameter estimates would be infeasible without an integrated model, we argue that integrated models will strengthen ecological theory by connecting theoretical and mathematical models directly to empirical data. Although integrated models remain conceptually and computationally challenging, integrating ecological data among levels is likely to be an important step toward unifying ecology among levels
A translational framework for public health research
<p><b>Background</b></p>
<p>The paradigm of translational medicine that underpins frameworks such as the Cooksey report on the funding of health research does not adequately reflect the complex reality of the public health environment. We therefore outline a translational framework for public health research.</p>
<p><b>Discussion</b></p>
<p>Our framework redefines the objective of translation from that of institutionalising effective interventions to that of improving population health by influencing both individual and collective determinants of health. It incorporates epidemiological perspectives with those of the social sciences, recognising that many types of research may contribute to the shaping of policy, practice and future research. It also identifies a pivotal role for evidence synthesis and the importance of non-linear and intersectoral interfaces with the public realm.</p>
<p><b>Summary</b></p>
<p>We propose a research agenda to advance the field and argue that resources for 'applied' or 'translational' public health research should be deployed across the framework, not reserved for 'dissemination' or 'implementation'.</p>
How Jupiter's Unusual Magnetospheric Topology Structures Its Aurora
Jupiter's bright persistent polar aurora and Earth's dark polar region
indicate that the planets' magnetospheric topologies are very different.
High-resolution global simulations show that the reconnection rate at the
interface between the interplanetary and jovian magnetic fields is too slow to
generate a magnetically open, Earth-like polar cap on the timescale of
planetary rotation, resulting in only a small crescent-shaped region of
magnetic flux interconnected with the interplanetary magnetic field. Most of
the jovian polar cap is threaded by helical magnetic flux that closes within
the planetary interior, extends into the outer magnetosphere and piles-up near
its dawnside flank where fast differential plasma rotation pulls the field
lines sunward. This unusual magnetic topology provides new insights into
Jupiter's distinctive auroral morphology
What change in outcomes after cardiac arrest is necessary to change practice? Results of an international survey
Background: Efficient trials of interventions for patients with out-of-hospital cardiac arrest (OHCA) should have adequate but not excess power to detect a difference in outcomes. The minimum clinically important difference (MCID) is the threshold value in outcomes observed in a trial at which providers should choose to adopt a treatment. There has been limited assessment of MCID for outcomes after OHCA. Therefore, we conducted an international survey of individuals interested in cardiac resuscitation to define the MCID for a range of outcomes after OHCA. Methods: A brief survey instrument was developed and modified by consensus. Included were open-ended responses. The survey included an illustrative example of a hypothetical randomized study with distributions of outcomes based on those in a public use datafile from a previous trial. Elicited information included the minimum significant difference required in an outcome to change clinical practice. The population of interest was emergency physicians or other practitioners of acute cardiovascular research. Results: Usable responses were obtained from 160 respondents (50% of surveyed) in 46 countries (79% of surveyed). MCIDs tended to increase as baseline outcomes increased. For a population of patients with 25% survival to discharge and 20% favorable neurologic status at discharge, the MCID were median 5 (interquartile range [IQR] 3, 10) percent for survival to discharge; median 5 (IQR 2, 10) percent for favorable neurologic status at discharge, median 4 (IQR 2, 9) days of ICU-free survival and median 4 (IQR 2, 8) days of hospital-free survival. Conclusion: Reported MCIDs for outcomes after OHCA vary according to the outcome considered as well as the baseline rate of achieving it. MCIDs of ICU-free survival or hospital-free survival may be useful to accelerate the rate of evidence-based change in resuscitation care. (C) 2016 Elsevier Ireland Ltd. All rights reserved.Peer reviewe
A search for charged massive long-lived particles
We report on a search for charged massive long-lived particles (CMLLPs),
based on 5.2 fb of integrated luminosity collected with the D0 detector
at the Fermilab Tevatron collider. We search for events in which one
or more particles are reconstructed as muons but have speed and ionization
energy loss inconsistent with muons produced in beam collisions.
CMLLPs are predicted in several theories of physics beyond the standard model.
We exclude pair-produced long-lived gaugino-like charginos below 267 GeV and
higgsino-like charginos below 217 GeV at 95% C.L., as well as long-lived scalar
top quarks with mass below 285 GeV.Comment: submitted to Phys. Rev. Letter
Religious revelation, secrecy and the limits of visual representation
This article seeks to contribute to a more adequate understanding of the adoption of modern audiovisual mass media by contemporary religious groups. It does so by examining Pentecostal-charismatic churches as well as the Christian mass culture instigated by its popularity, and so-called traditional religion in Ghana, which develop markedly different attitudes towards audiovisual mass media and assume different positions in the public sphere. Taking into account the complicated entanglement of traditional religion and Pentecostalism, approaching both religions from a perspective of mediation which regards media as intrinsic to religion, and seeking to avoid the pitfall of overestimating the power of modern mass media to determine the world, this article seeks to move beyond an unproductive recurrence to oppositions such as tradition and modernity, or religion and technology. It is argued that instead of taking as a point of departure more or less set ideas about the nexus of vision and modernity, the adoption of new mass media by religious groups needs to be analyzed by a detailed ethnographic investigation of how these new media transform existing practices of religious mediation. Special emphasis is placed on the tension between the possibilities of gaining public presence through new media, and the difficulty in authorizing these media, and the experiences they induce, as authentic. Copyright © 2006 SAGE Publications
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
Past and future adaptation pathways
Adaptation pathways are increasingly being used as a foresight tool to help guide the implementation of climate change adaptation and deliberate transformation. This paper applies a pathways lens as a hindsight tool to provide new understanding about past change and adaptation relevant for improving future adaptation pathways approaches. Four case studies of past adaptations to change are examined: Solomon Islands Communities, Canadian forest-dependent communities, a Transylvanian village, and responses to climate adaptation policies in Australia. The results highlight that responses to change in these diverse case studies involve complex transitions that gradually create new conditions and trajectories; manifest as multiple but inter-related pathways of change and response at different social or spatial scales (e.g. different paths for different households or communities); have legacies and continuities across time that affect future pathways of change; are affected by power in complex ways; and can create further change and need for adaptation. Analyses also highlight that when working with prospective adaptation approaches as a response to climate change there is a need to consider: (1) underlying assumptions, values and principles associated with the future; (2) the existence of inter-connected multiple pathways and their implications for reinforcing existing social inequalities; and (3) how understanding past change provides inspiration for new and transformative futures. Overall, the paper concludes that shifts towards analyses for change rather than simply about change, such as adaptation pathways, will require more careful consideration of underlying ontological assumptions about the relationships between past, present and future
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