Numerical simulation of transom-stern waves

The flow field generated by a transom-stern hullform is a complex, broad-banded, three-dimensional phenomenon marked by a large breaking wave. This unsteady multiphase turbulent flow feature is difficult to study experimentally and simulate numerically. The results of a set of numerical simulations, which use the Numerical Flow Analysis (NFA) code, of the flow around the Model 5673 transom stern at speeds covering both wet- and dry-transom operating conditions are shown in the accompanying fluid dynamics video. The numerical predictions for wet-transom and dry-transom conditions are presented to demonstrate the current state of the art in the simulation of ship generated breaking waves. The interested reader is referred to Drazen et al. (2010) for a detailed and comprehensive comparison with experiments conducted at the Naval Surface Warfare Center Carderock Division (NSWCCD).Comment: Fluid Dynamics Video for 2010 APS Division of Fluid Dynamics Gallery of Fluid Motion include

Do dried blood spots have the potential to support result management processes in routine sports drug testing?—Part 3: LC–MS/MS‐based peptide analysis for dried blood spot sampling time point estimation

Along with the recent acknowledgement of the World Anti-Doping Agency to use dried blood spot (DBS) samples for routine doping control purposes, there have been propositions to use DBS as a matrix that allows regular proactive remotely supervised self-sampling, providing potential longitudinal monitoring of an athlete's exposure to doping agents. However, several organizational aspects have to be considered before implementation, such as the verification of the sample collections time point. Based on a previous untargeted proteomics workflow utilizing liquid chromatography–high-resolution mass spectrometry (LC–HRMS) to identify protein/peptide markers to define the time since deposition of a bloodstain, the aim of the current study was to develop a targeted LC–HRMS/MS analytical method for promising peptidic target analytes. A long-term DBS storage experiment was carried out over a 3-month period (sample collection time points: 0, 2, 4, 7, 14, 21, 28, 42, 56, 70, 84 and 91 days) with DBS samples of 10 volunteers for longitudinal investigation of signal abundance changes of targeted peptide sequences at different storage temperatures (room temperature [RT], 4°C and −20°C). Prior to experimental analysis, LC–HRMS/MS method characteristics were successfully assessed, including intraday precision, carryover and sample extract stability. For estimation of DBS sample collection time points, ratios of two peptides that originate from the same protein prior to tryptic digestion were created. Two targeted peptide area ratios were found to significantly increase after being stored at RT for 28 days, representing potential markers for future use in routine doping controls that contribute to advancing complementary avenues in anti-doping

Prognostically controlled comparison of dialysis and renal transplantation

Prognostically controlled comparison of dialysis and renal transplantation. Because the comparison of survival in patients with renal failure treated by dialysis and transplantation may be biased by pretreatment prognostic differences in the patients who receive these two therapies, we quantified the pretreatment prognosis of all 430 dialysis and transplant patients who began therapy for end-stage renal disease at two hospitals from 1970 to 1980. Five pretreatment factors had a statistically significant adverse effect on survival: age, duration of diabetes, left ventricular failure, myocardial infarction, and other serious comorbid illness. Dialysis patients had a worse pretreatment prognosis than transplant patients did. When we controlled for these pretreatment differences, the actuarial 5-year patient survivals were 80% for dialysis (D), 79% for cadaver transplantation (CT), and 91% for living donor transplantation (LDT), (P = 0.9 for CT vs. D, and P = 0.05 for LDT vs. D). This similarity in survival with dialysis and cadaver transplantation was quite different from the results obtained when pretreatment prognosis was not controlled; the uncontrolled 5-year patient survivals were 43% for D, 77% for CT, and 89% for LDT (P < 0.001 for CT vs. D, and P < 0.001 for LDT vs. D). Our data suggest that the major factor determining differences in survival with dialysis and renal transplantation is not the relative efficacy of the two treatments but the pretreatment prognostic status of the patients chosen to receive them.Une comparaison contrôlée de façon pronostique entre la dialyse et la transplantation rénale. Puisque la comparaison de la survie des malades en insuffisance rénale traités par dialyse ou par transplantation peut être biaisée par des différences pronostiques pré-thérapeutiques entre les malades qui reçoivent ces deux traitements, nous avons quantifié le pronostic pré-thérapeutique de l'ensemble des 430 malades dialysés et transplantés qui ont commencé le traitement de leur insuffisance rénale dans deux hôpitaux de 1970 à 1980. Cinq facteurs préthérapeutiques possédaient un effet adverse statistiquement significatif sur la survie: l'âge, la durée du diabète, une insuffisance ventriculaire gauche, un infarctus du myocarde, et une autre maladie sérieuse associée. Les dialysés avaient un pronostic pré-thérapeutique plus mauvais que les transplantés. Lorsque nous avons contrôlé ces différences pré-thérapeutiques, la survie actuarielle à 5 ans des malades était de 80% pour la dialyse (D), 79% pour la transplantation cadavérique (CT), et 91% pour la transplantation avec donneur vivant (LDT) (P = 0,9 pour CT contre D, et P = 0,05 pour LDT contre D). Cette similitude de survie en dialyse ou après transplantation cadavérique était très différente des résultats obtenus lorsque le pronostic pré-thérapeutique n'était pas contrôlé; les survies non contrôlées à 5 ans des malades étaient de 43% pour D, 77% pour CT, et 89% pour LDT (P < 0,001 pour CT contre D, et P < 0,001 pour LDT contre D). Nos données suggèrent que le facteur principal déterminant les différences de survie en dialyse ou après transplantation rénale n'est pas l'efficacité relative des deux traitements, mais l'état pronostique pré-thérapeutique des malades choisis pour les recevoir

2004 EW95: A Phyllosilicate-bearing Carbonaceous Asteroid in the Kuiper Belt

Models of the Solar System's dynamical evolution predict the dispersal of primitive planetesimals from their formative regions amongst the gas-giant planets due to the early phases of planetary migration. Consequently, carbonaceous objects were scattered both into the outer asteroid belt and out to the Kuiper Belt. These models predict that the Kuiper Belt should contain a small fraction of objects with carbonaceous surfaces, though to date, all reported visible reflectance spectra of small Kuiper Belt Objects (KBOs) are linear and featureless. We report the unusual reflectance spectrum of a small KBO, (120216) 2004 EW95, exhibiting a large drop in its near-UV reflectance and a broad shallow optical absorption feature centered at ~700 nm which is detected at greater than 4-sigma significance. These features, confirmed through multiple epochs of spectral photometry and spectroscopy, have respectively been associated with ferric oxides and phyllosilicates. The spectrum bears striking resemblance to those of some C-type asteroids, suggesting that 2004 EW95 may share a common origin with those objects. 2004 EW95 orbits the Sun in a stable mean motion resonance with Neptune, at relatively high eccentricity and inclination, suggesting it may have been emplaced there by some past dynamical instability. These results appear consistent with the aforementioned model predictions and are the first to show a reliably confirmed detection of silicate material on a small KBO.Comment: 8 pages, 3 figures, 1 table, accepted, in pres

Acute stress differentially affects spatial configuration learning in high and low cortisol-responding healthy adults

Background: Stress and stress hormones modulate memory formation in various ways that are relevant to our understanding of stress-related psychopathology, such as posttraumatic stress disorder (PTSD). Particular relevance is attributed to efficient memory formation sustained by the hippocampus and parahippocampus. This process is thought to reduce the occurrence of intrusions and flashbacks following trauma, but may be negatively affected by acute stress. Moreover, recent evidence suggests that the efficiency of visuo-spatial processing and learning based on the hippocampal area is related to PTSD symptoms. Objective: The current study investigated the effect of acute stress on spatial configuration learning using a spatial contextual cueing task (SCCT) known to heavily rely on structures in the parahippocampus. Method: Acute stress was induced by subjecting participants (N = 34) to the Maastricht Acute Stress Test (MAST). Following a counterbalanced within-subject approach, the effects of stress and the ensuing hormonal (i.e., cortisol) activity on subsequent SCCT performance were compared to SCCT performance following a no-stress control condition. Results: Acute stress did not impact SCCT learning overall, but opposing effects emerged for high versus low cortisol responders to the MAST. Learning scores following stress were reduced in low cortisol responders, while high cortisol-responding participants showed improved learning. Conclusions: The effects of stress on spatial configuration learning were moderated by the magnitude of endogenous cortisol secretion. These findings suggest a possible mechanism by which cortisol responses serve an adaptive function during stress and trauma, and this may prove to be a promising route for future research in this area

2004 EW_(95): A Phyllosilicate-bearing Carbonaceous Asteroid in the Kuiper Belt

Models of the Solar System's dynamical evolution predict the dispersal of primitive planetesimals from their formative regions among the gas-giant planets due to the early phases of planetary migration. Consequently, carbonaceous objects were scattered both into the outer asteroid belt and out to the Kuiper Belt. These models predict that the Kuiper Belt should contain a small fraction of objects with carbonaceous surfaces, though to date, all reported visible reflectance spectra of small Kuiper Belt Objects (KBOs) are linear and featureless. We report the unusual reflectance spectrum of a small KBO, (120216) 2004 EW_(95), exhibiting a large drop in its near-UV reflectance and a broad shallow optical absorption feature centered at ~700 nm, which is detected at greater than 4σ significance. These features, confirmed through multiple epochs of spectral photometry and spectroscopy, have respectively been associated with ferric oxides and phyllosilicates. The spectrum bears striking resemblance to those of some C-type asteroids, suggesting that 2004 EW_(95) may share a common origin with those objects. 2004 EW95 orbits the Sun in a stable mean motion resonance with Neptune, at relatively high eccentricity and inclination, suggesting it may have been emplaced there by some past dynamical instability. These results appear consistent with the aforementioned model predictions and are the first to show a reliably confirmed detection of silicate material on a small KBO

Metagenomic and geochemical characterization of pockmarked sediments overlaying the Troll petroleum reservoir in the North Sea

Background Pockmarks (depressions in the seabed) have been discovered throughout the world’s oceans and are often related to hydrocarbon seepage. Although high concentrations of pockmarks are present in the seabed overlaying the Troll oil and gas reservoir in the northern North Sea, geological surveys have not detected hydrocarbon seepage in this area at the present time. In this study we have used metagenomics to characterize the prokaryotic communities inhabiting the surface sediments in the Troll area in relation to geochemical parameters, particularly related to hydrocarbon presence. We also investigated the possibility of increased potential for methane oxidation related to the pockmarks. Five metagenomes from pockmarks and plain seabed sediments were sequenced by pyrosequencing (Roche/454) technology. In addition, two metagenomes from seabed sediments geologically unlikely to be influenced by hydrocarbon seepage (the Oslofjord) were included. The taxonomic distribution and metabolic potential of the metagenomes were analyzed by multivariate analysis and statistical comparisons to reveal variation within and between the two sampling areas. Results The main difference identified between the two sampling areas was an overabundance of predominantly autotrophic nitrifiers, especially Nitrosopumilus, and oligotrophic marine Gammaproteobacteria in the Troll metagenomes compared to the Oslofjord. Increased potential for degradation of hydrocarbons, especially aromatic hydrocarbons, was detected in two of the Troll samples: one pockmark sample and one from the plain seabed. Although presence of methanotrophic organisms was indicated in all samples, no overabundance in pockmark samples compared to the Oslofjord samples supports no, or only low level, methane seepage in the Troll pockmarks at the present time. Conclusions Given the relatively low content of total organic carbon and great depths of hydrocarbon containing sediments in the Troll area, it is possible that at least part of the carbon source available for the predominantly autotrophic nitrifiers thriving in this area originates from sequential prokaryotic degradation and oxidation of hydrocarbons to CO2. By turning CO2 back into organic carbon this subcommunity could play an important environmental role in these dark oligotrophic sediments. The oxidation of ammonia to nitrite and nitrate in this process could further increase the supply of terminal electron acceptors for hydrocarbon degradation

A Multi-Parameter Measurement System for MEMS Anemoters for Data Collection with Machine Learning Outcomes

In order to generate consistent and comprehensive datasets for the application ofmachine learning algorithms to MEMS thermal flow sensors, a measurement set up was created.This system allows automatic data collection of large datasets involving parameters such as the angle of attack, humidity, temperature and flow speed. The electrical output signals in both the time and frequency domain can be measured for both AC and DC actuation. The setup has been able to fully characterize an anemometer by exposing it to flows of 0 to 5 m/s in steps of 0.02 m/s under anglesfrom -45 to 45° in steps of 5° at a constant temperature of 25 °C and humidity of 30 %RH and complete the measurement in 8 hours

Parametric study of the polarization dependence of nonlinear Breit-Wheeler pair creation process using two laser pulses

With the rapid development of high-power petawatt class lasers worldwide, exploring physics in the strong field QED regime will become one of the frontiers for laser-plasma interactions research. Particle-in-cell codes, including quantum emission processes, are powerful tools for predicting and analyzing future experiments where the physics of relativistic plasma is strongly affected by strong-field QED processes. The spin/polarization dependence of these quantum processes has been of recent interest. In this article, we perform a parametric study of the interaction of two laser pulses with an ultrarelativistic electron beam. The first pulse is optimized to generate high-energy photons by nonlinear Compton scattering and efficiently decelerate the electron beam through quantum radiation reaction. The second pulse is optimized to generate electron-positron pairs by nonlinear Breit-Wheeler decay of the photons with the maximum polarization dependence. This may be experimentally realized as a verification of the strong field QED framework, including the spin/polarization rates.Comment: 16 pages, 13 figure