Unmasking the Supernova Impostors

(ABRIDGED) The canonical picture of a supernova impostor is a -11 < M_V < -14 optical transient from a massive (M > 40Msun) star during which the star ejects a dense shell of material. Dust formed in the ejecta then obscures the star. In this picture, the geometric expansion of the shell leads to clear predictions for the evolution of the optical depths and hence the evolution of the optical through mid-IR emissions. Here we review the theory of this standard model and then examine the impostors SN1954J, SN1997bs, SN1999bw, SN2000ch, SN2001ac, SN2002bu, SN2002kg and SN2003gm, as well as the potential archetype eta Carinae. SN1999bw, SN2000ch, SN2001ac, SN2002bu and SN2003gm all show mid-IR emission indicative of dust, and the luminosities of SN1999bw, SN2001ac, SN2002bu and SN2003gm are dominated by dust emission. The properties of these sources are broadly inconsistent with the predictions of the canonical model. There are probably two classes of sources. In one class (eta Carinae, SN1954J, SN1997bs, and (maybe) SN2003gm), the optical transient is a signal that the star is entering a phase with very high mass loss rates that must last far longer than the visual transient. The second class (SN1999bw, SN2001ac, SN2002bu and (maybe) SN2003gm) has the different physics of SN2008S and the 2008 NGC300 transient, where they are obscured by dust re-forming in a pre-existing wind after it was destroyed by an explosive transient. There are no cases where the source at late times is significantly fainter than the progenitor star. All these dusty transients are occurring in relatively low mass (M 40Msun) stars radiating near the Eddington limit like eta Carinae. The durations and energetics of these transients cannot be properly characterized without near/mid-IR observations.Comment: 72 pages, 28 figures, submitted to Ap

Evidence for perinatal and child health care guidelines in crisis settings: can Cochrane help?

<p>Abstract</p> <p>Background</p> <p>It is important that healthcare provided in crisis settings is based on the best available research evidence. We reviewed guidelines for child and perinatal health care in crisis situations to determine whether they were based on research evidence, whether Cochrane systematic reviews were available in the clinical areas addressed by these guidelines and whether summaries of these reviews were provided in Evidence Aid.</p> <p>Methods</p> <p>Broad internet searches were undertaken to identify relevant guidelines. Guidelines were appraised using AGREE and the clinical areas that were relevant to perinatal or child health were extracted. We searched The Cochrane Database of Systematic Reviews to identify potentially relevant reviews. For each review we determined how many trials were included, and how many were conducted in resource-limited settings.</p> <p>Results</p> <p>Six guidelines met selection criteria. None of the included guidelines were clearly based on research evidence. 198 Cochrane reviews were potentially relevant to the guidelines. These reviews predominantly addressed nutrient supplementation, breastfeeding, malaria, maternal hypertension, premature labour and prevention of HIV transmission. Most reviews included studies from developing settings. However for large portions of the guidelines, particularly health services delivery, there were no relevant reviews. Only 18 (9.1%) reviews have summaries in Evidence Aid.</p> <p>Conclusions</p> <p>We did not identify any evidence-based guidelines for perinatal and child health care in disaster settings. We found many Cochrane reviews that could contribute to the evidence-base supporting future guidelines. However there are important issues to be addressed in terms of the relevance of the available reviews and increasing the number of reviews addressing health care delivery.</p

Development of a comprehensive cardiac atlas on a 1.5 Tesla Magnetic Resonance Linear Accelerator

Background and purpose: The 1.5 Tesla (T) Magnetic Resonance Linear Accelerator (MRL) provides an innovative modality for improved cardiac imaging when planning radiation treatment. No MRL based cardiac atlases currently exist, thus, we sought to comprehensively characterize cardiac substructures, including the conduction system, from cardiac images acquired using a 1.5 T MRL and provide contouring guidelines. Materials and methods: Five volunteers were enrolled in a prospective protocol (NCT03500081) and were imaged on the 1.5 T MRL with Half Fourier Single-Shot Turbo Spin-Echo (HASTE) and 3D Balanced Steady-State Free Precession (bSSFP) sequences in axial, short axis, and vertical long axis. Cardiac anatomy was contoured by (AS) and confirmed by a board certified cardiologist (JR) with expertise in cardiac MR imaging. Results: A total of five volunteers had images acquired with the HASTE sequence, with 21 contours created on each image. One of these volunteers had additional images obtained with 3D bSSFP sequences in the axial plane and additional images obtained with HASTE sequences in the key cardiac planes. Contouring guidelines were created and outlined. 15-16 contours were made for the short axis and vertical long axis. The cardiac conduction system was demonstrated with eleven representative contours. There was reasonable variation of contour volume across volunteers, with structures more clearly delineated on the 3D bSSFP sequence. Conclusions: We present a comprehensive cardiac atlas using novel images acquired prospectively on a 1.5 T MRL. This cardiac atlas provides a novel resource for radiation oncologists in delineating cardiac structures for treatment with radiotherapy, with special focus on the cardiac conduction system

Avaliação da interação entre resina composta e diferentes adesivos dentinários Evaluation of the interaction between composite resin and different dentin adhesives

O objetivo deste estudo foi avaliar a resistência à tração de quatro diferentes sistemas adesivos. Scotchbond Multi Purpose Plus, 3M (Grupo 1), Prime &amp; Bond 2.0, Dentsply (Grupo 2) ProBOND, Dentsply (Grupo 3), PAAMA 2, (Grupo 4) foram usados com a resina composta Glacier (SDI). Um grupo sem a utilização de qualquer sistema adesivo serviu como controle (Grupo 5). Cinqüenta espécimes foram divididos em cinco grupos com dez espécimes cada. Uma matriz de aço inoxidável com 6,0 mm de diâmetro e 1,0 mm de profundidade foi usada para se obterem dois discos de resina composta. A resina composta foi inserida em uma metade da matriz em pequenas porções e fotopolimerizada por 40 segundos. Os adesivos foram então aplicados na superfície dos discos de resina, seguindo a instrução dos fabricantes. A segunda parte da matriz foi colocada em posição e preenchida com a resina composta. Após uma hora, a matriz foi adaptada em um dispositivo especial na máquina de ensaios Kratos para determinar a resistência de união, a uma velocidade de 0,05 mm/min. Os resultados, expressos em kgf, foram: Grupo 1 (3,99 ± 1,47), Grupo 2 (4,24 ± 2,00), Grupo 3 (3,84 ± 0,88), Grupo 4 (4,33 ± 1,23) e Grupo 5 (4,21 ± 1,38). Os resultados foram analisados pelo teste estatístico ANOVA a um critério. Não houve diferença estatisticamente significante (p < 0,05) na resistência à tração entre os grupos. Baseado nos resultados deste estudo, pode-se concluir que não houve influência dos diferentes sistemas adesivos na resistência de união da resina composta.<br>The purpose of this study was to evaluate the tensile bond strength of four different adhesive systems. Scotchbond Multi-Purpose Plus, 3M (Group 1), Prime &amp; Bond 2.0, Dentsply (Group 2), ProBOND, Dentsply (Group 3), PAAMA 2, SDI (Group 4) were used with GLACIER (SDI) composite resin. One group without any adhesive was used as control (Group 5). Fifty specimens were divided into 5 groups of 10 each. A stainless steel split matrix with 6.00 mm diameter and 1.00 mm depth was used to obtain two discs of composite resin. The composite resin was applied into one half of the matrix in small portions and light cured for 40 seconds. The adhesives were then applied on the composite resin discs surfaces, following the manufacturer’s instructions. The second half of the matrix was assembled and the other half was filled with composite resin. After one hour, the matrix was adapted to a special device mounted in a Kratos testing machine to determine the tensile bond strength, at a crosshead speed of 0.5 mm/min. The results, expressed in KgF, were obtained: Group 1 (3.99 ± l.73), Group 2 (4.24 ± 1.91), Group 3 (3.84 ± 1.59), Group 4 (4.33 ± 1.82) and Group 5 (4.16 ± 1.79). Data were analyzed by one-way ANOVA. There were no statistical differences (p < 0.05) in bond strength between groups. Based on the results of this study, it can be concluded that there was no influence of the different adhesives in the bond strength to a composite resin