The LyAlpha Line Profiles of Ultraluminous Infrared Galaxies: Fast Winds and Lyman Continuum Leakage

We present new Hubble Space Telescope Cosmic Origins Spectrograph far-ultraviolet (far-UV) spectroscopy and Keck Echellete optical spectroscopy of 11 ultraluminous infrared galaxies (ULIRGs), a rare population of local galaxies experiencing massive gas inflows, extreme starbursts, and prominent outflows. We detect H Lyman alpha emission from 8 ULIRGs and the companion to IRAS09583+4714. In contrast to the P Cygni profiles often seen in galaxy spectra, the H Lyman alpha profiles exhibit prominent, blueshifted emission out to Doppler shifts exceeding -1000 km/s in three HII-dominated and two AGN-dominated ULIRGs. To better understand the role of resonance scattering in shaping the H Lyman alpha line profiles, we directly compare them to non-resonant emission lines in optical spectra. We find that the line wings are already present in the intrinsic nebular spectra, and scattering merely enhances the wings relative to the line core. The H Lyman alpha attenuation (as measured in the COS aperture) ranges from that of the far-UV continuum to over 100 times more. A simple radiative transfer model suggests the H Lyman alpha photons escape through cavities which have low column densities of neutral hydrogen and become optically thin to the Lyman continuum in the most advanced mergers. We show that the properties of the highly blueshifted line wings on the H Lyman alpha and optical emission-line profiles are consistent with emission from clumps of gas condensing out of a fast, hot wind. The luminosity of the H Lyman alpha emission increases non-linearly with the ULIRG bolometric luminosity and represents about 0.1 to 1% of the radiative cooling from the hot winds in the HII-dominated ULIRGs.Comment: Submitted to Ap

Reliability training

Discussed here is failure physics, the study of how products, hardware, software, and systems fail and what can be done about it. The intent is to impart useful information, to extend the limits of production capability, and to assist in achieving low cost reliable products. A review of reliability for the years 1940 to 2000 is given. Next, a review of mathematics is given as well as a description of what elements contribute to product failures. Basic reliability theory and the disciplines that allow us to control and eliminate failures are elucidated

IS ONLINE VIDEO-BASED EDUCATION AN EFFECTIVE METHOD TO TEACH BASIC SURGICAL SKILLS TO STUDENTS AND SURGICAL TRAINEES? A SYSTEMATIC REVIEW AND META-ANALYSIS

BACKGROUND: Online education has been increasingly utilized over the past decades. The COVID-19 pandemic accelerated the transition of conventional face-to-face curricula to online platforms, with limited evidence for its teaching efficacy. This systematic review aims to assess the effectiveness of online video-based education compared with standard conventional education in teaching basic surgical skills to surgical trainees and students undergoing medical training. METHODS: We performed a literature search in Embase, Medline, Cochrane CENTRAL and Scopus from inception until February 2022. Studies included were randomised controlled trials (RCTs) and observational studies. We included randomised controlled trials only for meta-analysis. The primary outcome was surgical skill proficiency. The secondary outcomes were participant perception, confidence and satisfaction. Two authors independently assessed the search results for eligibility, extracted the data and assessed the risk of bias using the Cochrane Risk of Bias tool 2. Where appropriate, we performed random effects meta-analyses of the pooled study data to calculate a standardized mean difference. RESULTS: A total of 11 studies met the inclusion criteria totaling 715 participants; 603 were included in qualitative analysis and 380 in meta-analysis. All included studies were assessed as having a low risk of bias. The majority of studies found no significant difference between conventional and video-based education in teaching basic surgical skills, three studies found video-based education was superior and one study found conventional education was superior. There was no statistically significant difference in skill proficiency between the two groups (standardized mean difference of -0.02 (95% CI: -0.34, 0.30); p=0.90). Video-based education results in an equivalent improvement in confidence and satisfaction rates. Additional benefits of video-based education include convenience, accessibility and efficiency. CONCLUSIONS: Basic surgical skills can be taught as effectively through online video-based education as conventional teaching methods. Online education should be utilized as an adjunct to medical curricula beyond the COVID-19 era

Clinical and Experimental Applications of NIR-LED Photobiomodulation

This review presents current research on the use of far-red to near-infrared (NIR) light treatment in various in vitro and in vivo models. Low-intensity light therapy, commonly referred to as “photobiomodulation,” uses light in the far-red to near-infrared region of the spectrum (630–1000 nm) and modulates numerous cellular functions. Positive effects of NIR–light-emitting diode (LED) light treatment include acceleration of wound healing, improved recovery from ischemic injury of the heart, and attenuated degeneration of injured optic nerves by improving mitochondrial energy metabolism and production. Various in vitro and in vivo models of mitochondrial dysfunction were treated with a variety of wavelengths of NIR-LED light. These studies were performed to determine the effect of NIR-LED light treatment on physiologic and pathologic processes. NIRLED light treatment stimulates the photoacceptor cytochrome c oxidase, resulting in increased energy metabolism and production. NIR-LED light treatment accelerates wound healing in ischemic rat and murine diabetic wound healing models, attenuates the retinotoxic effects of methanol-derived formic acid in rat models, and attenuates the developmental toxicity of dioxin in chicken embryos. Furthermore, NIR-LED light treatment prevents the development of oral mucositis in pediatric bone marrow transplant patients. The experimental results demonstrate that NIR-LED light treatment stimulates mitochondrial oxidative metabolism in vitro, and accelerates cell and tissue repair in vivo. NIR-LED light represents a novel, noninvasive, therapeutic intervention for the treatment of numerous diseases linked to mitochondrial dysfunction

Sensitivities of Low Energy Reactor Neutrino Experiments

The low energy part of the reactor neutrino spectra has not been experimentally measured. Its uncertainties limit the sensitivities in certain reactor neutrino experiments. The origin of these uncertainties are discussed, and the effects on measurements of neutrino interactions with electrons and nuclei are studied. Comparisons are made with existing results. In particular, the discrepancies between previous measurements with Standard Model expectations can be explained by an under-estimation of the low energy reactor neutrino spectra. To optimize the experimental sensitivities, measurements for \nuebar-e cross-sections should focus on events with large ($>$1.5 MeV) recoil energy while those for neutrino magnetic moment searches should be based on events $<$100 keV. The merits and attainable accuracies for neutrino-electron scattering experiments using artificial neutrino sources are discussed.Comment: 25 pages, 9 figure

Hepatitis B e antigen–negative chronic hepatitis b in Hong Kong

Hepatitis B e antigen–negative chronic hepatitis B (e−CHB) has been reported in Asia but its prevalence and clinical significance have not been determined. The aims of this study were to determine the prevalence of e−CHB in Hong Kong and the frequency of precore and core promoter mutations in these patients. A cross-sectional study was performed in 350 consecutive Chinese patients (230 men and 120 women; mean age ±SD, 42 ± 13 years) with chronic hepatitis B virus infection. A total of 243 (69%) patients were hepatitis B e antigen (HBeAg)-negative of whom 15% had clinical cirrhosis. In the remaining 85% of patients, 63% had normal and 22% had elevated transaminases. Serum hepatitis B virus (HBV) DNA was detectable using branched DNA assay in 46% of HBeAg-negative patients with clinical cirrhosis/elevated transaminases. Forty-five percent of the patients with e−CHB had the precore stop codon mutation, and an additional 41% had core promoter changes. There was no correlation between the presence of precore/core promoter mutations and liver disease or HBV-DNA levels. Overall, 17% of HBeAg-negative patients were viremic and had evidence of chronic liver disease (e−CHB) with mean HBV-DNA levels comparable with that in HBeAg-positive patients. In summary, we found that e−CHB may be present in up to 17% of HBeAg-negative patients seen in a tertiary referral center in Hong Kong. e−CHB may be a heterogenous condition and is not invariably associated with the precore HBV mutant. Population studies are needed to determine the true prevalence of e−CHB in Asia and to assess its natural course and response to treatment.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/34778/1/510310330_ftp.pd