46 research outputs found

    Pressure ulcer: an unreported complication of the Safeguard® hemostasis device. No need to crack under pressure

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    Diagnostic cardiac catheterizations are predominantly performed using the femoral artery access. Several devices have been developed to aid in the closure of femoral arteriotomy

    MAST and the impact of low aspect ration on tokamak physics

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    Mega ampere spherical tokamak (MAST) and the impact of low aspect ratio on tokamak physics are discussed. MAST is characterized by strong toroidicity, strong shaping and self fields, low magnetic field, high beta, and large plasma flow. MAST data have a

    Radiological protection of the patient in veterinary medicine and the role of ICRP

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    At the request of the Main Commission of the International Commission on Radiological Protection (ICRP), Task Group 107 (TG107) was set up to consider the issue of radiological protection of the patient in veterinary medicine. TG107, who authored this article, brought together information relating to the use of diagnostic imaging and radiation oncology in veterinary medicine. A number of specific areas were identified that appeared to be appropriate for attention by ICRP. These included the use of dose quantities and units, the need for re-evaluation of stochastic and deterministic risks from ionising radiation in animals, and the growing use of imaging and therapeutic equipment for animals that is little different from that available to humans. TG107 unanimously recommended that it was both appropriate and timely for ICRP to consider and advise on these issues, and the Main Commission agreed. This paper summarises the findings of TG107

    Deep Chandra, HST-COS, and Megacam Observations of the Phoenix Cluster: Extreme Star Formation and AGN Feedback on Hundred Kiloparsec Scales

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    We present new ultraviolet, optical, and X-ray data on the Phoenix galaxy cluster (SPT-CLJ2344-4243). Deep optical imaging reveals previously undetected filaments of star formation, extending to radii of ~50–100 kpc in multiple directions. Combined UV-optical spectroscopy of the central galaxy reveals a massive (2 × 109 M⊙), young (~4.5 Myr) population of stars, consistent with a time-averaged star formation rate of 610 ± 50 M⊙ yr−1. We report a strong detection of O vi λλ1032,1038, which appears to originate primarily in shock-heated gas, but may contain a substantial contribution (>1000 M⊙ yr−1) from the cooling intracluster medium (ICM). We confirm the presence of deep X-ray cavities in the inner ~10 kpc, which are among the most extreme examples of radio-mode feedback detected to date, implying jet powers of 2–7 × 1045 erg s−1. We provide evidence that the active galactic nucleus inflating these cavities may have only recently transitioned from "quasar-mode" to "radio-mode," and may currently be insufficient to completely offset cooling. A model-subtracted residual X-ray image reveals evidence for prior episodes of strong radio-mode feedback at radii of ~100 kpc, with extended "ghost" cavities indicating a prior epoch of feedback roughly 100 Myr ago. This residual image also exhibits significant asymmetry in the inner ~200 kpc (0.15R500), reminiscent of infalling cool clouds, either due to minor mergers or fragmentation of the cooling ICM. Taken together, these data reveal a rapidly evolving cool core which is rich with structure (both spatially and in temperature), is subject to a variety of highly energetic processes, and yet is cooling rapidly and forming stars along thin, narrow filaments

    Progress in simulating turbulent electron thermal transport in NSTX

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    Nonlinear simulations based on multiple NSTX discharge scenarios have progressed to help differentiate unique instability mechanisms and to validate with experimental turbulence and transport data. First nonlinear gyrokinetic simulations of microtearing (MT) turbulence in a high-beta NSTX H-mode discharge predict experimental levels of electron thermal transport that are dominated by magnetic flutter and increase with collisionality, roughly consistent with energy confinement times in dimensionless collisionality scaling experiments. Electron temperature gradient (ETG) simulations predict significant electron thermal transport in some low and high beta discharges when ion scales are suppressed by E x B shear. Although the predicted transport in H-modes is insensitive to variation in collisionality (inconsistent with confinement scaling), it is sensitive to variations in other parameters, particularly density gradient stabilization. In reversed shear (RS) Lmode discharges that exhibit electron internal transport barriers, ETG transport has also been shown to be suppressed nonlinearly by strong negative magnetic shear, s<<0. In many high beta plasmas, instabilities which exhibit a stiff beta dependence characteristic of kinetic ballooning modes (KBM) are sometimes found in the core region. However, they do not have a distinct finite beta threshold, instead transitioning gradually to a trapped electron mode (TEM) as beta is reduced to zero. Nonlinear simulations of this "hybrid" TEM/KBM predict significant transport in all channels, with substantial contributions from compressional magnetic perturbations. As multiple instabilities are often unstable simultaneously in the same plasma discharge, even on the same flux surface, unique parametric dependencies are discussed which may be useful for distinguishing the different mechanisms experimentally
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