Electron beam profile imaging in the presence of coherent optical radiation effects

High-brightness electron beams with low energy spread at existing and future x-ray free-electron lasers are affected by various collective beam self-interactions and microbunching instabilities. The corresponding coherent optical radiation effects, e.g., coherent optical transition radiation, render electron beam profile imaging impossible and become a serious issue for all kinds of electron beam diagnostics using imaging screens. Furthermore, coherent optical radiation effects can also be related to intrinsically ultrashort electron bunches or the existence of ultrashort spikes inside the electron bunches. In this paper, we discuss methods to suppress coherent optical radiation effects both by electron beam profile imaging in dispersive beamlines and by using scintillation imaging screens in combination with separation techniques. The suppression of coherent optical emission in dispersive beamlines is shown by analytical calculations, numerical simulations, and measurements. Transverse and longitudinal electron beam profile measurements in the presence of coherent optical radiation effects in non-dispersive beamlines are demonstrated by applying a temporal separation technique.Comment: 12 pages, 11 figures, submitted to Phys. Rev. ST Accel. Beam

Frequency Of Development Of Connective Tissue Disease In Statin-Users Versus Nonusers

Statins have pleiotropic properties that may affect the development of connective tissue diseases (CTD). The objective of this study was to compare the risk of CTD diagnoses in statin users and nonusers. This study was a propensity score-matched analysis of adult patients (30 to 85 years old) in the San Antonio military medical community. The study was divided into baseline (October 1, 2003 to September 30, 2005), and follow-up (October 1, 2005 to March 5, 2010) periods. Statin users received a statin prescription during fiscal year 2005. Nonusers did not receive a statin at any time during the study. The outcome measure was the occurrence of 3 diagnosis codes of the International Classification of Diseases, 9th Revision, Clinical Modification consistent with CTD. We described co-morbidities during the baseline period using the Charlson Comorbidity Index. We created a propensity score based on 41 variables. We then matched statin users and nonusers 1:1, using a caliper of 0.001. Of 46,488 patients who met study criteria (13,640 statin users and 32,848 nonusers), we matched 6,956 pairs of statin users and nonusers. Matched groups were similar in terms of patient age, gender, incidence of co-morbidities, total Charlson Comorbidity Index, health care use, and medication use. The odds ratio for CTD was lower in statin users than nonusers (odds ratio: 0.80; 95% confidence interval: 0.64 to 0.99; p = 0.05). Secondary analysis and sensitivity analysis confirmed these results. In conclusion, statin use was associated with a lower risk of CTD. Published by Elsevier Inc.Pharmac

Large-scale clustering of galaxies in general relativity

Several recent studies have shown how to properly calculate the observed clustering of galaxies in a relativistic context, and uncovered corrections to the Newtonian calculation that become significant on scales near the horizon. Here, we retrace these calculations and show that, on scales approaching the horizon, the observed galaxy power spectrum depends strongly on which gauge is assumed to relate the intrinsic fluctuations in galaxy density to matter perturbations through a linear bias relation. Starting from simple physical assumptions, we derive a gauge-invariant expression relating galaxy density perturbations to matter density perturbations on large scales, and show that it reduces to a linear bias relation in synchronous-comoving gauge, corroborating an assumption made in several recent papers. We evaluate the resulting observed galaxy power spectrum, and show that it leads to corrections similar to an effective non-Gaussian bias corresponding to a local (effective) fNL < 0.5. This number can serve as a guideline as to which surveys need to take into account relativistic effects. We also discuss the scale-dependent bias induced by primordial non-Gaussianity in the relativistic context, which again is simplest in synchronous-comoving gauge.Comment: 27 pages, 8 figure

The Effect of Prophylactic Knee Braces on Balance and Uninjured Knee Range of Motion

There has been numerous studies performed regarding the effectiveness of prophylactic knee braces (PKB) preventing knee injuries or the effect of PKB on injured knees, but minimal research is available on the effect of how PKB affect the functioning capacity of uninjured knees. PURPOSE: To examine the effects of two different types of PKB, hinged (HGB) and non-hinged (NHB), on uninjured preferred knee joint range of motion and dynamic balance in males and females. METHODS: Thirty subjects were recruited (male=15, female=15) with ages ranging from 18-28 years. Only participants with no history of any knee injuries or current knee problems were allowed to participate. Subjects were blinded to the purpose of the study, but were allowed practice trials for the dynamic balance test (Y-Balance test). Prior to experimental trials subjects were measured for body composition and knee brace size. All subjects underwent three experimental trials [HGB, NHB, and a no PKB control (CON)] on the same day in balanced cross-over design. During the treatment trials, the subjects wore the braces on their preferred leg. Each experimental trial was comprised of a test for dynamic balance and four tests for knee joint range of motion. Dynamic balance composite score, knee extension/flexion (°), and internal/external knee rotation (°) were compared between sex (M, F) and across PKB (HGB, NHB, CON) using an ANOVA (1 between, 1 within), α=0.05. Age and body composition differences between sex were examined using independent t-tests, α=0.05. RESULTS: M and F did not differ (p\u3e0.05) with regard to age, but did differ significantly (p\u3c0.05) in body mass, body stature, and percent body fat. For the sex main effect, when pooled across PKB (CON, HGB, NHG) M and F did not differ (p\u3e0.05) in knee flexion, internal knee rotation, right/left leg balance, but did differ significantly (p\u3c0.05) in knee extension (M=+0.8±1.8°, F=-0.6±2.4°) and external knee rotation (M=29.7±7.5°, F=35.9±9.7°). For the main effect for PKB, when pooled across sex external knee rotation and right/left leg balance did not differ (p\u3e0.05) between HGB, NHB, and CON, but both HGB and NHB differed significantly (p\u3c0.05) from CON for internal rotation (HGB=21.9±10.3°, NHB=22.5±9.8°, CON=24.8±10.0°), flexion (HGB=126.9±17.7°, NHB=125.7±15.9°, CON=139.0±6.8°), and extension (HGB=+0.7±1.4°, NHB=+=1.3±1.8°, CON=-1.7±2.2°). The sex x knee brace interaction was not significant (p\u3e0.05). CONCLUSION: PKB have no effect on dynamic balance, but appear to hinder the range of motion for most motions of the knee

How to Learn from Risk: Explicit Risk-Utility Reinforcement Learning for Efficient and Safe Driving Strategies

Autonomous driving has the potential to revolutionize mobility and is hence an active area of research. In practice, the behavior of autonomous vehicles must be acceptable, i.e., efficient, safe, and interpretable. While vanilla reinforcement learning (RL) finds performant behavioral strategies, they are often unsafe and uninterpretable. Safety is introduced through Safe RL approaches, but they still mostly remain uninterpretable as the learned behaviour is jointly optimized for safety and performance without modeling them separately. Interpretable machine learning is rarely applied to RL. This paper proposes SafeDQN, which allows to make the behavior of autonomous vehicles safe and interpretable while still being efficient. SafeDQN offers an understandable, semantic trade-off between the expected risk and the utility of actions while being algorithmically transparent. We show that SafeDQN finds interpretable and safe driving policies for a variety of scenarios and demonstrate how state-of-the-art saliency techniques can help to assess both risk and utility.Comment: 8 pages, 5 figure

Chemical ozone loss in the Arctic winter 1991–1992

Chemical ozone loss in winter 1991–1992 is recalculated based on observations of the HALOE satellite instrument, Version 19, ER-2 aircraft measurements and balloon data. HALOE satellite observations are shown to be reliable in the lower stratosphere below 400 K, at altitudes where the measurements are most likely disturbed by the enhanced sulfate aerosol loading, as a result of the Mt.~Pinatubo eruption in June 1991. Significant chemical ozone loss (13–17 DU) is observed below 380 K from Kiruna balloon observations and HALOE satellite data between December 1991 and March 1992. For the two winters after the Mt. Pinatubo eruption, HALOE satellite observations show a stronger extent of chemical ozone loss towards lower altitudes compared to other Arctic winters between 1991 and 2003. In spite of already occurring deactivation of chlorine in March 1992, MIPAS-B and LPMA balloon observations indicate that chlorine was still activated at lower altitudes, consistent with observed chemical ozone loss occurring between February and March and April. Large chemical ozone loss of more than 70 DU in the Arctic winter 1991–1992 as calculated in earlier studies is corroborated here

What on Earth have we been burning? Deciphering sedimentary records of pyrogenic carbon

Humans have interacted with fire for thousands of years, yet the utilization of fossil fuels marked the beginning of a new era. Ubiquitous in the environment, pyrogenic carbon (PyC) arises from incomplete combustion of biomass and fossil fuels, forming a continuum of condensed aromatic structures. Here we develop and evaluate 14C records for two complementary PyC molecular markers, benzene-polycarboxylic-acids (BPCAs) and polycyclic-aromatic-hydrocarbons (PAHs) preserved in aquatic sediments from a sub-urban and a remote catchment in the United States (U.S.) from mid-1700s to 1998. Results show that the majority of PyC stems from local sources and is transferred to aquatic sedimentary archives on sub-decadal to millennial time scales. Whereas a small portion stems from near-contemporaneous production and sedimentation, the majority of PyC (&lt;90%) experiences delayed transmission due to ‘pre-aging’ on millennial timescales in catchment soils prior to its ultimate deposition. BPCAs (soot) and PAHs (precursors of soot) trace fossil fuel-derived PyC. Both markers parallel historical records of the consumption of fossil fuels in U.S., yet never account for more than 19% total PyC. This study demonstrates that isotopic characterization of multiple tracers is necessary to constrain histories and inventories of PyC, and that sequestration of PyC can markedly lag its production

Resonance assignments of the microtubule-binding domain of the C. elegans spindle and kinetochore-associated protein 1

During mitosis, kinetochores coordinate the attachment of centromeric DNA to the dynamic plus ends of microtubules, which is hypothesized to pull sister chromatids toward opposing poles of the mitotic spindle. The outer kinetochore Ndc80 complex acts synergistically with the Ska (spindle and kinetochore-associated) complex to harness the energy of depolymerizing microtubules and power chromosome movement. The Ska complex is a hexamer consisting of two copies of the proteins Ska1, Ska2 and Ska3, respectively. The C-terminal domain of the spindle and kinetochore-associated protein 1 (Ska1) is the microtubule-binding domain of the Ska complex. We solved the solution structure of the C. elegans microtubule-binding domain (MTBD) of the protein Ska1 using NMR spectroscopy. Here, we report the resonance assignments of the MTBD of C. elegans Ska1.Austrian Science Fund (project P22170, and the doctoral school ‘‘DK Molecular Enzymology’’ (W901-B05)