A discrete-bubble model that predicts the rate of oxygen transfer in diffused-bubble systems is evaluated. Key inputs are the applied gas flow rate and the initial bubble size distribution. The model ...accounts for changes in the volume of individual bubbles due to transfer of oxygen and nitrogen (and hence changing partial pressure), variation in hydrostatic pressure, and changes in temperature. The bubble-rise velocity and mass-transfer coefficient, both known functions of the bubble diameter, are continually adjusted. The model is applied to predict the results of diffused-bubble oxygen transfer tests conducted in a 14-m deep tank at three air flow rates. All of the test data are predicted to within 15%. The range of bubble diameters (0.2–2
mm) spans the region of greatest variation in rise velocity and mass-transfer coefficient. For simplicity, the Sauter-mean diameter is used rather than the full bubble size distribution without loss of accuracy. The model should prove useful in the design and optimization of hypolimnetic oxygenation systems, as well as other diffused-bubble applications.
The European Spallation Source (ESS), currently under construction in Lund, Sweden, is a research center that will provide, by 2023, the world’s most powerful neutron source. The average power of the ...proton linac will be 5 MW. Pulsing this linac at higher frequency will make it possible to raise the average total beam power to 10 MW to produce, in parallel with the spallation neutron production, a very intense neutrino Super Beam of about 0.4 GeV mean neutrino energy. This will allow searching for leptonic CP violation at the second oscillation maximum where the sensitivity is about 3 times higher than at the first. The ESS neutrino Super Beam, ESSnuSB operated with a 2.0 GeV linac proton beam, together with a large underground Water Cherenkov detector located at 540 km from Lund, will make it possible to discover leptonic CP violation at 5σ significance level in 56% (65% for an upgrade to 2.5 GeV beam energy) of the leptonic CP-violating phase range after 10 years of data taking, assuming a 5% systematic error in the neutrino flux and 10% in the neutrino cross section. The paper presents the outstanding physics reach possible for CP violation with ESSnuSB obtainable under these assumptions for the systematic errors. It also describes the upgrade of the ESS accelerator complex required for ESSnuSB.
•A high heat flux actively cooled divertor component is thermally modeled with CFD.•CFC monoblocks are analyzed to verify peak steady-state temperatures do not exceed 1200°C.•A field line diffusion ...code is developed to determine the heat flux on the divertor components.•Iteration is required to develop a surface that meets the criteria and fits into the limited space.
Thehigh heat-flux divertor of the Wendelstein 7-X large stellarator experiment consists of 10 divertor units which are designed to carry a steady-state heat flux of 10MW/m2. However, the edge elements of this divertor are limited to only 5MW/m2, and may be overloaded in certain plasma scenarios. It is proposed to reduce this heat by placing an additional “scraper element” in each of the ten divertor locations. It will be constructed using carbon fiber composite (CFC) monoblock technology. The design of the monoblocks and the path of the cooling tubes must be optimized in order to survive the significant steady-state heat loads, provide adequate coverage for the existing divertor, be located within sub-millimeter accuracy, and take into account the boundaries to other in vessel components, all at a minimum cost. Computational fluid dynamics modeling has been performed to examine the thermal transfer through the monoblock swirl tube channels for the design of the monoblock orientation. An iterative physics modeling and computer aided design process is being performed to optimize the placement of the scraper element within the severe spatial restrictions.
The recent implementation of attosecond and few-femtosecond X-ray pump/X-ray probe schemes in large-scale free-electron laser facilities has opened the way to visualize fast nuclear dynamics in ...molecules with unprecedented temporal and spatial resolution. Here, we present the results of theoretical calculations showing how polarization-averaged molecular-frame photoelectron angular distributions (PA-MFPADs) can be used to visualize the dynamics of hydrogen migration in methanol, ethanol, propanol, and isopropyl alcohol dications generated by X-ray irradiation of the corresponding neutral species. We show that changes in the PA-MFPADs with the pump–probe delay as a result of intramolecular photoelectron diffraction carry information on the dynamics of hydrogen migration in real space. Although visualization of this dynamics is more straightforward in the smaller systems, methanol and ethanol, one can still recognize the signature of that motion in propanol and isopropyl alcohol and assign a tentative path to it. A possible pathway for a corresponding experiment requires an angularly resolved detection of photoelectrons in coincidence with molecular fragment ions used to define a molecular frame of reference. Such studies have become, in principle, possible since the first XFELs with sufficiently high repetition rates have emerged. To further support our findings, we provide experimental evidence of H migration in ethanol−OD from ion–ion coincidence measurements performed with synchrotron radiation.
The prediction of a supersonic solar wind
was first confirmed by spacecraft near Earth
and later by spacecraft at heliocentric distances as small as 62 solar radii
. These missions showed that plasma ...accelerates as it emerges from the corona, aided by unidentified processes that transport energy outwards from the Sun before depositing it in the wind. Alfvénic fluctuations are a promising candidate for such a process because they are seen in the corona and solar wind and contain considerable energy
. Magnetic tension forces the corona to co-rotate with the Sun, but any residual rotation far from the Sun reported until now has been much smaller than the amplitude of waves and deflections from interacting wind streams
. Here we report observations of solar-wind plasma at heliocentric distances of about 35 solar radii
, well within the distance at which stream interactions become important. We find that Alfvén waves organize into structured velocity spikes with duration of up to minutes, which are associated with propagating S-like bends in the magnetic-field lines. We detect an increasing rotational component to the flow velocity of the solar wind around the Sun, peaking at 35 to 50 kilometres per second-considerably above the amplitude of the waves. These flows exceed classical velocity predictions of a few kilometres per second, challenging models of circulation in the corona and calling into question our understanding of how stars lose angular momentum and spin down as they age
.
Slips, trips, and falls are leading causes of musculoskeletal injuries in firefighters. Researchers have hypothesized that heat stress is the major contributing factor to these fireground injuries.
...To examine the effect of environmental conditions, including hot and ambient temperatures, and exercise on functional and physiological outcome measures, including balance, rectal temperature, and perceived exertion.
Randomized controlled clinical trial.
Laboratory environmental chamber.
A total of 13 healthy, active career firefighters (age = 26 ± 6 years range = 19-35 years, height = 178.61 ± 4.93 cm, mass = 86.56 ± 16.13 kg).
Independent variables consisted of 3 conditions (exercise in heat 37.41°C, standing in heat 37.56°C, and exercise in ambient temperature 14.24°C) and 3 data-collection times (preintervention, postintervention, and postrecovery). Each condition was separated from the others by at least 1 week and lasted a maximum of 40 minutes or until the participant reached volitional fatigue or a rectal temperature of 40.0°C.
Firefighting-specific functional balance performance index, rectal temperature, and rating of perceived exertion.
Exercise in the heat decreased functional balance, increased rectal temperature, and altered the perception of exertion compared with the other intervention conditions.
A bout of exercise in a hot, humid environment increased rectal temperature in a similar way to that reported in the physically active population and negatively affected measures of functional balance. Rather than independently affecting balance, the factors of exercise and heat stress appeared to combine, leading to an increased likelihood of slips, trips, and falls.
This article assesses the reliability and validity of the Cocaine Selective Severity Assessment (CSSA), a measure of cocaine abstinence signs and symptoms. Interrater reliability and scale internal ...consistency were high. Initial CSSA scores were significantly higher in cocaine-dependent subjects than in alcohol-dependent subjects. Initial CSSA scores were highly correlated with recent cocaine use and with severity measures from the Addiction Severity Index (ASI) including the interviewer severity rating and composite score in the drug section. Among cocaine-dependent subjects, initial CSSA scores were higher for those who failed to achieve abstinence or who subsequently dropped out of treatment. Further, CSSA scores showed consistent and marked declines over time for subjects who continued in treatment and remained abstinent. The CSSA appears to be a reliable and valid measure of cocaine abstinence symptoms and a useful predictor of negative outcomes in cocaine dependence treatment.
Background
Despite negative troponins and nonischemic electrocardiograms (ECGs), patients at moderate risk for acute coronary syndrome (ACS) are frequently admitted. The objective of this study was ...to describe the major adverse cardiac event (MACE) rate in moderate‐risk patients and how it differs based on history of coronary artery disease (CAD).
Methods
A secondary analysis of the HEART Pathway implementation study was conducted. This prospective interrupted time‐series study accrued adults with possible ACS from three sites (November 2013–January 2016). This analysis excluded low‐risk patients determined by emergency providers' HEART Pathway assessments. Non–low‐risk patients were further classified as high risk, based on elevated troponin measures or ischemic ECG findings or as moderate risk, based on HEAR score ≥ 4, negative troponin measures, and a nonischemic ECG. Moderate‐risk patients were then stratified by the presence or absence of prior CAD (MI, revascularization, or ≥70% coronary stenosis). MACE (death, myocardial infarction, or revascularization) at 30 days was determined from health records, insurance claims, and death index data. MACE rates were compared among groups using a chi‐square test and likelihood ratios (LRs) were calculated.
Results
Among 4,550 patients with HEART Pathway assessments, 24.8% (1,130/4,550) were high risk and 37.7% (1715/4550) were moderate risk. MACE at 30 days occurred in 3.1% (53/1,715; 95% confidence interval CI = 2.3% to 4.0%) of moderate‐risk patients. Among moderate‐risk patients, MACE occurred in 7.1% (36/508, 95% CI = 5.1% to 9.8%) of patients with known CAD versus 1.4% (17/1,207, 95% CI = 0.9% to 2.3%) in patients without known prior CAD (p < 0.0001). The negative LR for 30‐day MACE among moderate‐risk patients without prior CAD was 0.08 (95% CI = 0.05 to 0.12).
Conclusion
MACE rates at 30 days were low among moderate‐risk patients but were significantly higher among those with prior CAD.
Out-of-hospital naloxone has been championed as a lifesaving solution during the opioid epidemic. However, the long-term outcomes of out-of-hospital naloxone recipients are unknown. The objectives of ...this study are to describe the 1-year mortality of presumed opioid overdose victims identified by receiving out-of-hospital naloxone and to determine which patient factors are associated with subsequent mortality.
This was a regional retrospective cohort study of out-of-hospital records from 7 North Carolina counties from January 1, 2015 to February 28, 2017. Patients who received out-of-hospital naloxone were included. Out-of-hospital providers subjectively assessed patients for improvement after administering naloxone. Naloxone recipients were cross-referenced with the North Carolina death index to examine mortality at days 0, 1, 30, and 365. Naloxone recipient mortality was compared with the age-adjusted, at-large population’s mortality rate in 2017. Generalized estimating equations and Cox proportional hazards models were used to assess for mortality-associated factors.
Of 3,085 out-of-hospital naloxone encounters, 72.7% of patients (n=2,244) improved, whereas 27.3% (n=841) had no improvement with naloxone. At day 365, 12.0% (n=269) of the improved subgroup, 22.6% (n=190) of the no improvement subgroup, and 14.9% (n=459) of the whole population were dead. Naloxone recipients who improved were 13.2 times (95% confidence interval 13.0 to 13.3) more likely to be dead at 1 year than a member of the general populace after age adjusting of the at-large population to match this study population. Older age and being black were associated with 1-year mortality, whereas sex and multiple overdoses were not.
Opioid overdose identified by receiving out-of-hospital naloxone with clinical improvement carries a 13-fold increase in mortality compared to the general population. This suggests that this is a high-risk population that deserves attention from public health officials, policymakers, and health care providers in regard to the development of long-term solutions.
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