8,161 research outputs found

    Addressing Ethical Issues in Studying Men’s Traumatic Stress

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    Like many human experiences, traumatic stress is highly gendered. Over the past several decades, a sub-stantial number of empirical studies have explored ethical issues in traumatic stress research. However, these studies have typically reported female samples or failed to account for the influence of gender in their analyses of mixed-sex samples. By extension, ethical issues that are relevant to male participants in traumatic stress research are poorly understood. After briefly exploring why the vulnerabilities of male participants are under-explored in traumatic stress research, this article highlights many ethical issues that are important to address when men participate in traumatic stress research, concluding with some sugges-tions for how these might be taken up to advance the field

    Advances in the pathophysiology and treatment of heparin-induced thrombocytopenia.

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    PURPOSE OF REVIEW: To review the recent developments in understanding the pathophysiology of heparin-induced thrombocytopenia (HIT) and in applying this knowledge to the treatment of patients with suspected and proven HIT. RECENT FINDINGS: HIT pathophysiology is dynamic and complex. HIT pathophysiology is initiated by four essential components--heparin (Hep), platelet factor 4 (PF4), IgG antibodies against the Hep-PF4 complex, and platelet FcγRIIa. HIT is propagated by activated platelets, monocytes, endothelial cells, and coagulation proteins. Insights into the unique HIT antibody response continue to emerge, but without consensus as to the relative roles of B cells, T cells, and antigen-presenting cells. Platelet activation via FcγRIIa, the sine qua non of HIT, has become much better appreciated. Therapy remains challenging for several reasons. Suspected HIT is more frequent than proven HIT, because of the widespread use of Hep and the inadequacies of current diagnostic tests and scoring systems. In proven HIT, approved treatments reduce but do not eliminate thrombosis, and have substantial bleeding risk. Rational novel therapeutic strategies, directed at the initiating steps in HIT pathophysiology and with potential combinations staged over time, are in various phases of development. SUMMARY: Progress continues in understanding the breadth of molecular and cellular players in HIT. Translation to improved diagnosis and treatment is needed

    Low-Altitude Reconnection Inflow-Outflow Observations during a 2010 November 3 Solar Eruption

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    For a solar flare occurring on 2010 November 3, we present observations using several SDO/AIA extreme-ultraviolet (EUV) passbands of an erupting flux rope followed by inflows sweeping into a current sheet region. The inflows are soon followed by outflows appearing to originate from near the termination point of the inflowing motion - an observation in line with standard magnetic reconnection models. We measure average inflow plane-of-sky speeds to range from ~150-690 km/s with the initial, high-temperature inflows being the fastest. Using the inflow speeds and a range of Alfven speeds, we estimate the Alfvenic Mach number which appears to decrease with time. We also provide inflow and outflow times with respect to RHESSI count rates and find that the fast, high-temperature inflows occur simultaneously with a peak in the RHESSI thermal lightcurve. Five candidate inflow-outflow pairs are identified with no more than a minute delay between detections. The inflow speeds of these pairs are measured to be 10^2 km/s with outflow speeds ranging from 10^2-10^3 km/s - indicating acceleration during the reconnection process. The fastest of these outflows are in the form of apparently traveling density enhancements along the legs of the loops rather than the loop apexes themselves. These flows could either be accelerated plasma, shocks, or waves prompted by reconnection. The measurements presented here show an order of magnitude difference between the retraction speeds of the loops and the speed of the density enhancements within the loops - presumably exiting the reconnection site.Comment: 31 pages, 13 figures, 1 table, Accepted to ApJ (expected publication ~July 2012

    Phase diagram of the one-dimensional Holstein model of spinless fermions

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    The one-dimensional Holstein model of spinless fermions interacting with dispersionless phonons is studied using a new variant of the density matrix renormalisation group. By examining various low-energy excitations of finite chains, the metal-insulator phase boundary is determined precisely and agrees with the predictions of strong coupling theory in the anti-adiabatic regime and is consistent with renormalisation group arguments in the adiabatic regime. The Luttinger liquid parameters, determined by finite-size scaling, are consistent with a Kosterlitz-Thouless transition.Comment: Minor changes. 4 pages, 4 figures. To appear in Physical Review Letters 80 (1998) 560

    Upper Critical Field in a Spin-Charge Separated Superconductor

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    It is demonstrated that the spatial decay of the pair propagator in a Luttinger liquid with spin charge separation contains a logarithmic correction relative to the free fermi gas result in a finite interval between the spin and charge thermal lengths. It is argued that similar effects can be expected in higher dimensional systems with spin charge separation and that the temperature dependence of the upper critical field Hc2H_{c2} curve is a probe of this effect.Comment: 3 pages, postscript file (compressed and uuencoded

    Shocks and Thermal Conduction Fronts in Retracting Reconnected Flux Tubes

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    We present a model for plasma heating produced by time-dependent, spatially localized reconnection within a flare current sheet separating skewed magnetic fields. The reconnection creates flux tubes of new connectivity which subsequently retract at Alfv\'enic speeds from the reconnection site. Heating occurs in gas-dynamic shocks which develop inside these tubes. Here we present generalized thin flux tube equations for the dynamics of reconnected flux tubes, including pressure-driven parallel dynamics as well as temperature dependent, anisotropic viscosity and thermal conductivity. The evolution of tubes embedded in a uniform, skewed magnetic field, following reconnection in a patch, is studied through numerical solutions of these equations, for solar coronal conditions. Even though viscosity and thermal conductivity are negligible in the quiet solar corona, the strong gas-dynamic shocks generated by compressing plasma inside reconnected flux tubes generate large velocity and temperature gradients along the tube, rendering the diffusive processes dominant. They determine the thickness of the shock that evolves up to a steady-state value, although this condition may not be reached in the short times involved in a flare. For realistic solar coronal parameters, this steady-state shock thickness might be as long as the entire flux tube. For strong shocks at low Prandtl numbers, typical of the solar corona, the gas-dynamic shock consists of an isothermal sub-shock where all the compression and cooling occur, preceded by a thermal front where the temperature increases and most of the heating occurs. We estimate the length of each of these sub-regions and the speed of their propagation.Comment: 39 pages (AASTeX: 29 pages of text, 10 figures), accepted for publication in the Astrophysical Journa
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