3,799 research outputs found
Planar Josephson Tunnel Junctions in a Transverse Magnetic Field
Traditionally, since the discovery of the Josephson effect in 1962, the
magnetic diffraction pattern of planar Josephson tunnel junctions has been
recorded with the field applied in the plane of the junction. Here we discuss
the static junction properties in a transverse magnetic field where
demagnetization effects imposed by the junction geometry and configuration of
the electrodes are important. Measurements of the critical current versus
magnetic field in planar Nb-based high-quality junctions with different
geometry, size and critical current density show that it is advantageous to use
a transverse magnetic field rather than an in-plane field to suppress the
Josephson tunnel current and Fiske resonances in practical applications.Comment: 5 pages, 2 figures, submitted to Journal of Applied Physic
A Comparison of Ultraviolet, Optical, and X-Ray Imagery of Selected Fields in the Cygnus Loop
During the Astro-1 and Astro-2 Space Shuttle missions in 1990 and 1995, far
ultraviolet (FUV) images of five 40' diameter fields around the rim of the
Cygnus Loop supernova remnant were observed with the Ultraviolet Imaging
Telescope (UIT). These fields sampled a broad range of conditions including
both radiative and nonradiative shocks in various geometries and physical
scales. In these shocks, the UIT B5 band samples predominantly CIV 1550 and the
hydrogen two-photon recombination continuum. Smaller contri- butions are made
by emission lines of HeII 1640 and OIII] 1665. We present these new FUV images
and compare them with optical Halpha and [OIII], and ROSAT HRI X-ray images.
Comparing the UIT images with those from the other bands provides new insights
into the spatial variations and locations of these different types of emission.
By comparing against shock model calculations and published FUV spectroscopy at
select locations, we surmise that resonance scattering in the strong FUV
permitted lines is widespread in the Cygnus Loop, especially in the bright
optical filaments typically selected for observation in most previous studies.Comment: 21 pages with 10 figures. See http://www.pha.jhu.edu/~danforth/uit/
for full-resolution figure
Outcomes in Trials for Management of Caries Lesions (OuTMaC):protocol
Background
Clinical trials on caries lesion management use an abundance of outcomes, hampering comparison or combination of different study results and their efficient translation into clinical practice. Core outcome sets are an agreed standardized collection of outcomes which should be measured and reported in all trials for a specific clinical area. We aim to develop a core outcome set for trials investigating management of caries lesions in primary or permanent teeth conducted in primary or secondary care encompassing all stages of disease.
Methods
To identify existing outcomes, trials on prevention and trials on management of caries lesions will be screened systematically in four databases. Screening, extraction and deduplication will be performed by two researchers until consensus is reached. The definition of the core outcome set will by based on an e-Delhi consensus process involving key stakeholders namely patients, dentists, clinical researchers, health economists, statisticians, policy-makers and industry representatives. For the first stage of the Delphi process, a patient panel and a separate panel consisting of researchers, clinicians, teachers, industry affiliated researchers, policy-makers, and other interested parties will be held. An inclusive approach will be taken to involve panelists from a wide variety of socio-economic and geographic backgrounds. Results from the first round will be summarized and fed back to individuals for the second round, where panels will be combined and allowed to modify their scoring in light of the full panel’s opinion. Necessity for a third round will be dependent on the outcome of the first two. Agreement will be measured via defined consensus rules; up to a maximum of seven outcomes. If resources allow, we will investigate features that influence decision making for different groups.
Discussion
By using an explicit, transparent and inclusive multi-step consensus process, the planned core outcome set should be justifiable, relevant and comprehensive. The dissemination and application of this core outcome set should improve clinical trials on managing caries lesions and allow comparison, synthesis and implementation of scientific data.
Trial registration
Registered 12 April 2015 at COMET (http://www.comet-initiative.org
Universal restrictions to the conversion of heat into work derived from the analysis of the Nernst theorem as a uniform limit
We revisit the relationship between the Nernst theorem and the Kelvin-Planck
statement of the second law. We propose that the exchange of entropy uniformly
vanishes as the temperature goes to zero. The analysis of this assumption shows
that is equivalent to the fact that the compensation of a Carnot engine scales
with the absorbed heat so that the Nernst theorem should be embedded in the
statement of the second law.
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Se analiza la relaci{\'o}n entre el teorema de Nernst y el enunciado de
Kelvin-Planck del segundo principio de la termodin{\'a}mica. Se{\~n}alamos el
hecho de que el cambio de entrop{\'\i}a tiende uniformemente a cero cuando la
temperatura tiende a cero. El an{\'a}lisis de esta hip{\'o}tesis muestra que es
equivalente al hecho de que la compensaci{\'o}n de una m{\'a}quina de Carnot
escala con el calor absorbido del foco caliente, de forma que el teorema de
Nernst puede derivarse del enunciado del segundo principio.Comment: 8pp, 4 ff. Original in english. Also available translation into
spanish. Twocolumn format. RevTe
Reassurance Policing and Signal Crimes
A reassurance function for policing was first considered by American psychologist Charles Bahn (1974: 338) as “feelings of safety that a citizen experiences when he knows that a police officer or patrol car is nearby.” This idea was taken forward in Britain by Martin Innes and colleagues in the early 2000s through the development of a signal crimes perspective. At this time, British policing implemented a National Reassurance Policing Programme (NRPP) where local policing priorities were decided through consultation with local communities. The impact of reassurance policing has since spread and the approach has also been considered in Australia, Belgium, the Netherlands, and Sweden.
In this entry, the background to reassurance policing is considered with particular reference to the work of Charles Bahn and Martin Innes and colleagues. The development of a policy of reassurance policing in Britain is also examined. The successes and limitations of the approach are considered and three main issues identified: that reassurance needs to be a consideration for all policing; that increases in visible patrol need to be questioned (especially at a time of budget restraint); and that reassurance policing has the potential to be a model of democratic policing, but only if consultation is truly inclusive, for instance, including those that have been victimized and groups that have been targets of police activity such as young people, the homeless, and other minority and marginalized groups
Forward to the past: reinventing intelligence-led policing in Britain
Drawing on archival, secondary material and primary research, this paper examines 'Total Policing', the strategy recently adopted by London's Metropolitan Police. It situates that analysis within a critical examination of other innovative policing strategies previously employed in Britain. It argues that the prospects for Total Policing depend upon the resolution of long-standing problems such as: the inadequacy and inefficiency of local intelligence work; the paucity of evidence for the success of commanders' previous efforts to harness together the component parts of their forces in pursuit of a single mission; and, above all, a seeming inability to learn the lessons of the past. © 2013 © 2013 Taylor & Francis
A Century of Change towards Prevention and Minimal Intervention in Cariology
Publisher Copyright: © International & American Associations for Dental Research 2019. Copyright: Copyright 2019 Elsevier B.V., All rights reserved.Better understanding of dental caries and other oral conditions has guided new strategies to prevent disease and manage its consequences at individual and public health levels. This article discusses advances in prevention and minimal intervention dentistry over the last century by focusing on some milestones within scientific, clinical, and public health arenas, mainly in cariology but also beyond, highlighting current understanding and evidence with future prospects. Dentistry was initially established as a surgical specialty. Dental caries (similar to periodontitis) was considered to be an infectious disease 100 years ago. Its ubiquitous presence and rampant nature—coupled with limited diagnostic tools and therapeutic treatment options—meant that these dental diseases were managed mainly by excising affected tissue. The understanding of the diseases and a change in their prevalence, extent, and severity, with evolutions in operative techniques, technologies, and materials, have enabled a shift from surgical to preventive and minimal intervention dentistry approaches. Future challenges to embrace include continuing the dental profession’s move toward a more patient-centered, evidence-based, less invasive management of these diseases, focused on promoting and maintaining oral health in partnership with patients. In parallel, public health needs to continue to, for example, tackle social inequalities in dental health, develop better preventive and management options for existing disease risk groups (e.g., the growing aging population), and the development of reimbursement and health outcome models that facilitate implementation of these evolving strategies. A century ago, almost every treatment involved injections, a drill or scalpel, or a pair of forceps. Today, dentists have more options than ever before available to them. These are supported by evidence, have a minimal intervention focus, and result in better outcomes for patients. The profession’s greatest challenge is moving this evidence into practice.preprintPeer reviewe
Highlights of the mini-symposium on extracellular vesicles in inter-organismal communication, held in Munich, Germany, August 2018
All living organisms secrete molecules for intercellular communication. Recent research has revealed that extracellular vesicles (EVs) play an important role in inter-organismal cell-to-cell communication by transporting diverse messenger molecules, including RNA, DNA, lipids and proteins. These discoveries have raised fundamental questions regarding EV biology. How are EVs biosynthesized and loaded with messenger/cargo molecules? How are EVs secreted into the extracellular matrix? What are the EV uptake mechanisms of recipient cells? As EVs are produced by all kind of organisms, from unicellular bacteria and protists, filamentous fungi and oomycetes, to complex multicellular life forms such as plants and animals, basic research in diverse model systems is urgently needed to shed light on the multifaceted biology of EVs and their role in inter-organismal communications. To help catalyse progress in this emerging field, a mini-symposium was held in Munich, Germany in August 2018. This report highlights recent progress and major questions being pursued across a very diverse group of model systems, all united by the question of how EVs contribute to inter-organismal communication
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On the maintenance and initiation of the intraseasonal oscillation in the NCEP/NCAR and ECMWF reanalyses and in the GLA and UKMO AMIP simulations
Julian Intraseasonal (Madden-Julian) oscillations are a dominant model of tropical variability (Madden and 1971, 1972). Satellite derived outgoing longwave radiation (OLR) and reanalyses from NCEP/NCAR and ECMWF are used as verification data in a study of intraseasonal variability in the Goddard Laboratory for Atmospheres (GLA) and the United Kingdom Meteorological Office (UKMO) atmospheric general circulation models. Sling0 et al. (1996) indicated that no model was able to capture the dominance of the intraseasonal oscillation (IO) found in the ECMWF/JDP analyses. However, in the case of the GLA and UKMO AMIP integrations, when a clear eastward propagating signal is evident, the period of the oscillation is realistic.Therefore, in order to show the models in their best light, we examine the November-May period during which these models exhibited their strongest&most coherent IO`s. 1987/88 from observations and the reanalyses will be compared with 1986/87 from GLA and 1980/81 from UKMO. Case studies are important since specific processes/mechanisms may be evident which might otherwise be obscured by cornpositing over many years (e.g., Matthews et al. 1996). During the active phase of the IO, convection migrates from the Indian Ocean to the western/central Pacific Ocean, and into the SPCZ. To demonstrate this, we have calculated an IO index to be used for lagged correlation analysis. This pentad averaged time series is constructed from 20-100 day bandpass filtered 200hPa velocity potential over the region 1OO{degrees}- 140{degrees}E, lO{degrees}N- 10{degrees} S from the NCEP/NCAR reanalysis (not shown; the IO index from the ECMWF reanalysis is virtually identical with the NCEP/NCAR IO index [correlation coefficient=0.987]). This region was chosen since this is where the diabatic heating associated with the IO is greatest. This IO index is then correlated with pentad averaged OLR at various time lags. Convection first arises over the western Indian Ocean on day -15. Through day 0 the convective envelope matures quickly, dominating the eastern Indian Ocean, the Maritime continent and much of Australia. Subsequently, the extent of the convection decreases, with the strongest enhancement located in the SPCZ. The simulated convection, particularly in the GLA model, is most realistic over the western/central Pacific Ocean and the SPCZ. However, both models fail to simulate IO related convection over the Indian Ocean and the propagation eastward into the west Pacific. The maintenance and initiation of the intraseasonal oscillation has also been investigated. Evaporative wind feedback hypothesizes that evaporation to the east of the convection is fundamental for maintaining the eastward migration of the convection. To examine the viability of this hypothesis we have correlated the IO index with 20-100 day bandpass filtered latent heat flux from NCEP/NCAR reanalysis and ECWMF reanalysis. Both reanalyses indicate that evaporation is enhanced to the west of the convection, particularly from day -5 onward, with both reanalyses exhibiting virtually identical lag correlation patterns. This result indicates that evaporative wind feedback is not the dominant process by which the eastward propagation of the intraseasonal oscillation is maintained. Correlations of the simulated IO indexes with filtered latent heat flux from the GLA and UKMO integrations are also shown. In the GLA simulation, enhanced evaporation tends to develop in-place over the west Pacific warm pool, while in the UISMO simulation westward propagation of enhanced evaporation is evident. Thus, the models do not simulate the processes suggested by the reanalyses that occur during the eastward propagation of the IO. While our results suggest a wave-CISK type mechanism , the contribution due to frictional convergence is not apparent. It is suggested that lack of an interactive ocean may be associated with the models systematic failure to simulate the eastward transition of convection and the latent heat flux from the Indian Ocean into the western Pacific Ocean. Examination of observed SST and its relationship to the active phase of the intraseasonal oscillation suggests that air-sea interaction may be important during the course of the evolution of the IO. To explore this in more detail, we show the correlation of the IO index with filtered observed SST (and skin temperature over land from the ECMWF reanalysis) for the 1987/88 case study
Notes on the Third Law of Thermodynamics.I
We analyze some aspects of the third law of thermodynamics. We first review
both the entropic version (N) and the unattainability version (U) and the
relation occurring between them. Then, we heuristically interpret (N) as a
continuity boundary condition for thermodynamics at the boundary T=0 of the
thermodynamic domain. On a rigorous mathematical footing, we discuss the third
law both in Carath\'eodory's approach and in Gibbs' one. Carath\'eodory's
approach is fundamental in order to understand the nature of the surface T=0.
In fact, in this approach, under suitable mathematical conditions, T=0 appears
as a leaf of the foliation of the thermodynamic manifold associated with the
non-singular integrable Pfaffian form . Being a leaf, it cannot
intersect any other leaf const. of the foliation. We show that (N) is
equivalent to the requirement that T=0 is a leaf. In Gibbs' approach, the
peculiar nature of T=0 appears to be less evident because the existence of the
entropy is a postulate; nevertheless, it is still possible to conclude that the
lowest value of the entropy has to belong to the boundary of the convex set
where the function is defined.Comment: 29 pages, 2 figures; RevTex fil
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