The effect of beam-driven return current instability on solar hard X-ray bursts

The problem of electrostatic wave generation by a return current driven by a small area electron beam during solar hard X-ray bursts is discussed. The marginal stability method is used to solve numerically the electron and ion heating equations for a prescribed beam current evolution. When ion-acoustic waves are considered, the method appears satisfactory and, following an initial phase of Coulomb resistivity in which T sub e/T sub i rise, predicts a rapid heating of substantial plasma volumes by anomalous ohmic dissipation. This hot plasma emits so much thermal bremsstrahlung that, contrary to previous expectations, the unstable beam-plasma system actually emits more hard X-rays than does the beam in the purely collisional thick target regime relevant to larger injection areas. Inclusion of ion-cyclotron waves results in ion-acoustic wave onset at lower T sub e/T sub i and a marginal stability treatment yields unphysical results

Spectral infrared hemispherical reflectance measurements for LDEF tray clamps

Infrared hemispherical reflectance measurements that were made on 58 chromic acid anodized tray clamps from LDEF are described. The measurements were made using a hemiellipsoidal mirror reflectometer with interferometer for wavelengths between 2-15 microns. The tray clamps investigated were from locations about the entire spacecraft and provided the opportunity for comparing the effects of atomic oxygen at each location. Results indicate there was essentially no dependence on atomic oxygen fluence for the surfaces studied, but there did appear to be a slight dependence on solar radiation exposure. The reflectances of the front sides of the tray clamps consistently were slightly higher than for the protected rear tray clamp surfaces

Minimal Bending Energies of Bilayer Polyhedra

Motivated by recent experiments on bilayer polyhedra composed of amphiphilic molecules, we study the elastic bending energies of bilayer vesicles forming polyhedral shapes. Allowing for segregation of excess amphiphiles along the ridges of polyhedra, we find that bilayer polyhedra can indeed have lower bending energies than spherical bilayer vesicles. However, our analysis also implies that, contrary to what has been suggested on the basis of experiments, the snub dodecahedron, rather than the icosahedron, generally represents the energetically favorable shape of bilayer polyhedra

Review of Diagnostic Imaging Modalities for the Surveillance of Melanoma Patients

As melanoma survival rates continue to increase, optimal surveillance strategies for recurrences are needed, as are effective imaging modalities. Therefore, we performed a meta-analysis to evaluate the current state of imaging modalities for surveillance of melanoma in the published medical literature to determine the sensitivity, specificity, and positive predictive values of ultrasonography, computed tomography (CT), positron emission tomography (PET), and CT-PET combined. Ultrasonography was found to be the most sensitive and specific for detecting lymph node metastases, and PET-CT was the most sensitive and specific for detecting distant metastases. In addition to identifying appropriate surveillance methods, future studies should focus on the most effective and cost-effective intervals for performing these tests. In addition, the results from the meta-analysis related to sensitivity and specificity of the tests should be made available to doctors in community practice

Land grading for irrigation : design and construction (1993)

Land grading is reshaping the surface of land to planned grades for irrigation and subsequent drainage. Land grading permits uniform and efficient application of irrigation water without excessive erosion and at the same time provides for adequate surface drainage. A plane surface (uniform row and cross slopes) is easiest to manage and maintain. All lands to be graded for irrigation should be suitable for use as irrigated land and for the proposed methods of water application. Water supplies and the delivery system should be sufficient to make irrigation practical for the crops to be grown and the irrigation water application methods to be used

National Vascular Registry: 2014 Progress Report.

The National Vascular Registry is commissioned by the Healthcare Quality Improvement Partnership (HQIP) to measure the quality and outcomes of care for patients who undergo major vascular surgery in NHS hospitals in England and Wales. It aims to provide comparative information on the performance of NHS hospitals and thereby support local quality improvement as well as inform patients about the care delivered in the NHS. As such, all NHS hospitals in England, Wales, Scotland and Northern Ireland are encouraged to participate in the Registry. The measures used to describe the patterns and outcomes of care are drawn from various national guidelines including: the “2014 The Provision of Services for Patients with Vascular Disease” and the Quality Improvement Frameworks published by the Vascular Society, and the National Institute for Health and Care Excellence (NICE) guidelines on stroke and peripheral arterial disease. In 2014, the Registry published NHS trust and surgeon-level information for elective infrarenal Abdominal Aortic Aneurysm (AAA) repair and carotid endarterectomy on the Registry website. From 28 October, information on both procedures has been available on the www.vsqip.org.uk website for all UK NHS trusts that currently perform them. For English NHS trusts, the same information was published for individual consultants, as part of NHS England’s “Everyone Counts: Planning for Patients 2013/4” initiative. Consultant-level information was also published for NHS hospitals in Wales, Scotland and Northern Ireland for consenting surgeons. This progress report aims to complement that information by (1) providing an overview of care delivered by the NHS at a national level, and (2) describing various developments within the National Vascular Registry. The Registry will publish its next annual report on major vascular surgery in November 2015

National Vascular Registry: 2015 Annual Report.

The National Vascular Registry is commissioned by the Healthcare Quality Improvement Partnership (HQIP) to measure the quality and outcomes of care for patients who undergo major vascular surgery in NHS hospitals in England and Wales. It aims to provide comparative information on the performance of NHS vascular units and thereby support local quality improvement as well as inform patients about major vascular interventions delivered in the NHS. As such, all NHS hospitals in England, Wales, Scotland and Northern Ireland are encouraged to participate in the Registry. The measures used to describe the patterns and outcomes of care are drawn from various national guidelines including: the “Provision of Services for Patients with Vascular Disease” document and the Quality Improvement Frameworks published by the Vascular Society, and the National Institute for Health and Care Excellence (NICE) guidelines on stroke and peripheral arterial disease. This report provides a description of the care provided by NHS vascular units, and contains information on the process and outcomes of care for: (i) patients undergoing abdominal aortic aneurysm (AAA) repair, (ii) patients undergoing carotid endarterectomy, (iii) patients undergoing a revascularisation procedure (angioplasty/stent or bypass) or major amputation for lower-limb peripheral arterial disease (PAD). In addition, the report presents the findings of an organisational audit conducted in August 2015

Fractionating Choice: A Study on Reward Discrimination, Preference, and Relative Valuation in the Rat (Rattus Norvegicus)

Choice behavior combines discrimination between distinctive outcomes, preference for specific outcomes and relative valuation of comparable outcomes. Previous work has focused on 1 component (i.e., preference) disregarding other influential processes that might provide a more complete understanding. Animal models of choice have been explored primarily utilizing extensive training, limited freedom for multiple decisions and sparse behavioral measures constrained to a single phase of motivated action. The present study used a paradigm that combines different elements of previous methods with the goal to distinguish among components of choice and explore how well components match predictions based on risk-sensitive foraging strategies. In order to analyze discrimination and relative valuation, it was necessary to have an option that shifted and an option that remained constant. Shifting outcomes among weeks included a change in single-option outcome (0 to 1 to 2 pellets) or a change in mixed-option outcome (0 or 5 to 0 or 3 to 0 or 1 pellets). Constant outcomes among weeks were also mixed-option (0 or 3 pellets) or single-option (1 pellet). Shifting single-option outcomes among weeks led to better discrimination, more robust preference and significant incentive contrast effects for the alternative outcome. Shifting multioptions altered choice components and led to dissociations among discrimination, preference, and reduced contrast effects. During extinction, all components were impacted with the greatest deficits during the shifting mixed-option outcome sessions. Results suggest choice behavior can be optimized for 1 component but suboptimal for others depending upon the complexity of alterations in outcome value between options

Outcomes following oesophagectomy in patients with oesophageal cancer: a secondary analysis of the ICNARC Case Mix Programme Database

Introduction: This report describes the case mix and outcomes of patients with oesophageal cancer admitted to adult critical care units following elective oesophageal surgery in England, Wales and Northern Ireland. Methods: Admissions to critical care following elective oesophageal surgery for malignancy were identified using data from the Intensive Care National Audit and Research Centre (ICNARC) Case Mix Programme Database. Information on admissions between December 1995 and September 2007 were extracted and the association between in-hospital mortality and patient characteristics on admission to critical care was assessed using multiple logistic regression analysis. The performance of three prognostic models (Simplified Acute Physiology Score (SAPS) II, Acute Physiology and Chronic Health Evaluation (APACHE) II and the ICNARC physiology score) was also evaluated. Results: Between 1995 and 2007, there were 7227 admissions to 181 critical care units following oesophageal surgery for malignancy. Overall mortality in critical care was 4.4% and in-hospital mortality was 11%, although both declined steadily over time. Eight hundred and seventy-three (12.2%) patients were readmitted to critical care, most commonly for respiratory complications (49%) and surgical complications (25%). Readmitted patients had a critical care unit mortality of 24.7% and in-hospital mortality of 33.9%. Overall in-hospital mortality was associated with patient age, and various physiological measurements on admission to critical care (partial pressure of arterial oxygen (PaO2):fraction of inspired oxygen (FiO2) ratio, lowest arterial pH, mechanical ventilation, serum albumin, urea and creatinine). The three prognostic models evaluated performed poorly in measures of discrimination, calibration and goodness of fit. Conclusions: Surgery for oesophageal malignancy continues to be associated with significant morbidity and mortality. Age and organ dysfunction in the early postoperative period are associated with an increased risk of death. Postoperative serum albumin is confirmed as an additional prognostic factor. More work is required to determine how this knowledge may improve clinical management

Elastic energy of polyhedral bilayer vesicles

In recent experiments [M. Dubois, B. Dem\'e, T. Gulik-Krzywicki, J.-C. Dedieu, C. Vautrin, S. D\'esert, E. Perez, and T. Zemb, Nature (London) Vol. 411, 672 (2001)] the spontaneous formation of hollow bilayer vesicles with polyhedral symmetry has been observed. On the basis of the experimental phenomenology it was suggested [M. Dubois, V. Lizunov, A. Meister, T. Gulik-Krzywicki, J. M. Verbavatz, E. Perez, J. Zimmerberg, and T. Zemb, Proc. Natl. Acad. Sci. U.S.A. Vol. 101, 15082 (2004)] that the mechanism for the formation of bilayer polyhedra is minimization of elastic bending energy. Motivated by these experiments, we study the elastic bending energy of polyhedral bilayer vesicles. In agreement with experiments, and provided that excess amphiphiles exhibiting spontaneous curvature are present in sufficient quantity, we find that polyhedral bilayer vesicles can indeed be energetically favorable compared to spherical bilayer vesicles. Consistent with experimental observations we also find that the bending energy associated with the vertices of bilayer polyhedra can be locally reduced through the formation of pores. However, the stabilization of polyhedral bilayer vesicles over spherical bilayer vesicles relies crucially on molecular segregation of excess amphiphiles along the ridges rather than the vertices of bilayer polyhedra. Furthermore, our analysis implies that, contrary to what has been suggested on the basis of experiments, the icosahedron does not minimize elastic bending energy among arbitrary polyhedral shapes and sizes. Instead, we find that, for large polyhedron sizes, the snub dodecahedron and the snub cube both have lower total bending energies than the icosahedron