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This paper presents a theoretical and experimental study of the long-standing fluid mechanics problem involving the temporal resolution of a large localised initial disturbance into a sequence of solitary waves. This problem is of fundamental importance in a range of applications, including tsunami and internal ocean wave modelling. This study is performed in the context of the viscous fluid conduit system – the driven, cylindrical, free interface between two miscible Stokes fluids with high viscosity contrast. Owing to buoyancy-induced nonlinear self-steepening balanced by stress-induced interfacial dispersion, the disturbance evolves into a slowly modulated wavetrain and further into a sequence of solitary waves. An extension of Whitham modulation theory, termed the solitary wave resolution method, is used to resolve the fission of an initial disturbance into solitary waves. The developed theory predicts the relationship between the initial disturbance’s profile, the number of emergent solitary waves and their amplitude distribution, quantifying an extension of the well-known soliton resolution conjecture from integrable systems to non-integrable systems that often provide a more accurate modelling of physical systems. The theoretical predictions for the fluid conduit system are confirmed both numerically and experimentally. The number of observed solitary waves is consistently within one to two waves of the prediction, and the amplitude distribution shows remarkable agreement. Universal properties of solitary wave fission in other fluid dynamics problems are identified.
Optical parametric chirped-pulse amplification (OPCPA) [Dubietis et al., Opt. Commun. 88, 437 (1992)] implemented by multikilojoule Nd:glass pump lasers is a promising approach to produce ultraintense pulses (
). Technologies are being developed to upgrade the OMEGA EP Laser System with the goal to pump an optical parametric amplifier line (EP OPAL) with two of the OMEGA EP beamlines. The resulting ultraintense pulses (1.5 kJ, 20 fs,
) would be used jointly with picosecond and nanosecond pulses produced by the other two beamlines. A midscale OPAL pumped by the Multi-Terawatt (MTW) laser is being constructed to produce 7.5-J, 15-fs pulses and demonstrate scalable technologies suitable for the upgrade. MTW OPAL will share a target area with the MTW laser (50 J, 1 to 100 ps), enabling several joint-shot configurations. We report on the status of the MTW OPAL system, and the technology development required for this class of all-OPCPA laser system for ultraintense pulses.
Broiler breeders conduct their breeding programs only in optimal environments, claiming that because farmers are instructed to provide the broilers with optimal management, genotype by environment interactions (GxE) are not important for the broiler industry. However, with the rapid development of the poultry industry worldwide, high-performance broiler stocks are now being imported to developing countries where environmental control, mainly the mitigation of hot climates, is not feasible. Moreover, results from several studies suggest that due to the increase in genetic potential for rapid growth rate, resulting from successful breeding programs, broilers are becoming more sensitive to rather small environmental deviations from optimal conditions (Leenstra and Cahaner, 1991; Cahaner and Leenstra, 1992; Cahaner et al., 1993; Settar et al., 1999; Yunis et al, 1999). Hence, also in developed countries, many broilers will be, or are already being reared under suboptimal hot environments.
A combination of better management and genetic selection for good health and fertility would provide a more effective long term solution for economic loss due to diseases and poor fertility. This would also help to address public concerns about the use of medical treatment in milk production. A balance in the genetic improvement of health and fertility together with milk production could be achieved through their inclusion in national genetic selection indices, for which genetic parameters are needed. One of the main objectives of this study was to estimate genetic parameters for various disease and fertility traits in the UK dairy cattle population, using records from a national recording scheme run by Livestock Services UK Ltd. Genetic analysis of traits recorded as present or absent (binary traits; e.g. diseases) requires the use of non-linear threshold models, because linear models require normality assumptions (e.g., Gianola 1982). The other objective of this study was to estimate genetic parameters for binary disease and fertility traits based on threshold animal models and to compare results with those from linear animal models.
Globular clusters (GCs) harbour a large number of close binaries which are hard to identify optically due to high stellar densities. Observing these GCs in X-rays, in which the compact binaries are bright, diminishes the over-crowding problem. Using the new generation of X-ray observatories, it is possible to identify populations of neutron star low mass X-ray binaries, cataclysmic variables and millisecond pulsars as well as other types of binaries. We present the spectra of a variety of binaries that we have identified in four GCs observed by XMM-Newton. We show that through population studies we can begin to understand the formation of individual classes of binaries in GCs and hence start to unfold the complex evolutionary paths of these systems.
To describe the investigation and control of a cluster of Serratia marcescens bacteremia in a 505-bed tertiary-care center.
Cluster cases were defined as all patients with S. marcescens bacteremia between March 2 and April 7, 2014, who were found to have identical or related blood isolates determined by molecular typing with pulsed-field gel electrophoresis. Cases were compared using bivariate analysis with controls admitted at the same time and to the same service as the cases, in a 4:1 ratio.
In total, 6 patients developed S. marcescens bacteremia within 48 hours after admission within the above period. Of these, 5 patients had identical Serratia isolates determined by molecular typing, and were included in a case-control study. Exposure to the post-anesthesia care unit was a risk factor identified in bivariate analysis. Evidence of tampered opioid-containing syringes on several hospital units was discovered soon after the initial cluster case presented, and a full narcotic diversion investigation was conducted. A nurse working in the post-anesthesia care unit was identified as the employee responsible for the drug diversion and was epidemiologically linked to all 5 patients in the cluster. No further cases were identified once the implicated employee’s job was terminated.
Illicit drug use by healthcare workers remains an important mechanism for the development of bloodstream infections in hospitalized patients. Active mechanisms and systems should remain in place to prevent, detect, and control narcotic drug diversions and associated patient harm in the healthcare setting.
Subjective reports of insomnia and hypersomnia are common in bipolar disorder (BD). It is unclear to what extent these relate to underlying circadian rhythm disturbance (CRD). In this study we aimed to objectively assess sleep and circadian rhythm in a cohort of patients with BD compared to matched controls.
Forty-six patients with BD and 42 controls had comprehensive sleep/circadian rhythm assessment with respiratory sleep studies, prolonged accelerometry over 3 weeks, sleep questionnaires and diaries, melatonin levels, alongside mood, psychosocial functioning and quality of life (QoL) questionnaires.
Twenty-three (50%) patients with BD had abnormal sleep, of whom 12 (52%) had CRD and 29% had obstructive sleep apnoea. Patients with abnormal sleep had lower 24-h melatonin secretion compared to controls and patients with normal sleep. Abnormal sleep/CRD in BD was associated with impaired functioning and worse QoL.
BD is associated with high rates of abnormal sleep and CRD. The association between these disorders, mood and functioning, and the direction of causality, warrants further investigation.
In the coastal mountain chain of southern Victoria Land approximately 4,000 km.2 of glacier-cut valleys and dividing ranges are almost completely ice-free, while the surrounding areas are fully glacierized.
In the ice-free Wright Valley and Victoria Valley systems evidence of four glaciations is recognized. The earliest two glaciations were the most extensive; glaciers flowed eastwards from the ice plateau through the coastal ranges and cut broad valleys extending to McMurdo Sound and the Ross Sea. The moraines of these glaciations are thin and highly weathered. The third glaciation was less extensive, consisting of advances by smaller glaciers derived from the inland ice plateau, the Wilson Piedmont Glacier and névé fields in the dividing ranges. The surfaces of moraines of this glaciation are now partly covered by saline lakes, evaporite deposits and extensive areas of desert pavements strewn with ventifacts. The fourth and youngest glaciation comprised small advances by remnants of the plateau-fed valley glaciers. Thick boulder moraines of this glaciation overlie earlier deposits.
During each glaciation the greatest volume of ice was derived from the inland ice plateau. The volume of ice entering the valleys was dependent on the difference in altitude between the plateau surface and subglacial rock thresholds at the valley heads. Decrease in the surface level of the inland ice plateau caused the rock thresholds to increasingly hinder the eastward flow of plateau ice until practically no ice could flow down into the valleys, thereby terminating the glaciation. Such a condition exists at the present time.
Little is known about the precursors of suicide risk among primary-care patients. This study aimed to examine suicide risk in relation to patterns of clinical consultation, psychotropic drug prescribing, and psychiatric diagnoses.
Nested case-control study in the Clinical Practice Research Datalink (CPRD), England. Patients aged ⩾16 years who died by suicide during 2002–2011 (N = 2384) were matched on gender, age and practice with up to 20 living control patients (N = 46 899).
Risk was raised among non-consulting patients, and increased sharply with rising number of consultations in the preceding year [⩾12 consultations v. 1: unadjusted odds ratio (OR) 6.0, 95% confidence interval (CI) 4.9–7.3]. Markedly elevated risk was also associated with the prescribing of multiple psychotropic medication types (⩾5 types v. 0: OR 62.6, CI 44.3–88.4) and with having several psychiatric diagnoses (⩾4 diagnoses v. 0: OR 31.1, CI 19.3–50.1). Risk was also raised among patients living in more socially deprived localities. The confounding effect of multiple psychotropic drug types largely accounted for the rising risk gradient observed with increasing consultation frequency.
A greater proportion of patients with several psychiatric diagnoses, those prescribed multiple psychotropic medication types, and those who consult at very high frequency might be considered for referral to mental health services by their general practitioners. Non-consulters are also at increased risk, which suggests that conventional models of primary care may not be effective in meeting the needs of all people in the community experiencing major psychosocial difficulties.
Millimetre-band scans of the frequency space towards optically dim quasars is potentially a highly efficient method for detecting new high red-shift molecular absorption systems. Here we describe scans towards 7 quasars over wide bandwidths (up to 23 GHz) with sensitivity limits sufficient to detect the 4 redshifted absorbers already known. With wider frequency bands, highly efficient searches of large numbers of possibly obscured objects will yield many new molecular absorbers.
Accurate and complete reporting of study methods, results and interpretation are essential components for any scientific process, allowing end-users to evaluate the internal and external validity of a study. When animals are used in research, excellence in reporting is expected as a matter of continued ethical acceptability of animal use in the sciences. Our primary objective was to assess completeness of reporting for a series of studies relevant to mitigation of pain in neonatal piglets undergoing routine management procedures. Our second objective was to illustrate how authors can report the items in the Reporting guidElines For randomized controLled trials for livEstoCk and food safety (REFLECT) statement using examples from the animal welfare science literature. A total of 52 studies from 40 articles were evaluated using a modified REFLECT statement. No single study reported all REFLECT checklist items. Seven studies reported specific objectives with testable hypotheses. Six studies identified primary or secondary outcomes. Randomization and blinding were considered to be partially reported in 21 and 18 studies, respectively. No studies reported the rationale for sample sizes. Several studies failed to report key design features such as units for measurement, means, standard deviations, standard errors for continuous outcomes or comparative characteristics for categorical outcomes expressed as either rates or proportions. In the discipline of animal welfare science, authors, reviewers and editors are encouraged to use available reporting guidelines to ensure that scientific methods and results are adequately described and free of misrepresentations and inaccuracies. Complete and accurate reporting increases the ability to apply the results of studies to the decision-making process and prevent wastage of financial and animal resources.
Many upcoming surveys, particularly in the radio and optical domains, are designed to probe either the temporal and/or the spatial variability of a range of astronomical objects. In the light of these high resolution surveys, we review the subject of ultra-luminous X-ray (ULX) sources, which are thought to be accreting black holes for the most part. We also discuss the sub-class of ULXs known as the hyper-luminous X-ray sources, which may be accreting intermediate mass black holes. We focus on some of the open questions that will be addressed with the new facilities, such as the mass of the black hole in ULXs, their temporal variability and the nature of the state changes, their surrounding nebulae, and the nature of the region in which ULXs reside.
The UK has seen a significant transition from Defined Benefit (“DB”) to Defined Contribution (“DC”) for occupational pension saving. The planned automatic enrolment program starting in 2012 is expected to increase the use of DC. The main features of DC are that investment risk falls onto the individual during the pre-retirement phase and that there are no guarantees as to investment returns or the level of pension. In July 2012, Steve Webb, the Pensions Minister, challenged industry to think hard about meeting the need for more certainty about pension savings in DC plans and to consider providing an affordable ‘Money Safe’ guarantee where the member would get back at least the nominal value of their contributions (individual, employer and tax relief). This paper explores whether this is viable for the mass market.
Psychiatric in-patients are at high risk of suicide. Recent reductions in bed numbers in many countries may have affected this risk but few studies have specifically investigated temporal trends. We aimed to explore trends in psychiatric in-patient suicide over time.
A prospective study of all patients admitted to National Health Service (NHS) in-patient psychiatric care in England (1997–2008). Suicide rates were determined using National Confidential Inquiry and Hospital Episode Statistics (HES) data.
Over the study period there were 1942 psychiatric in-patient suicides. Between the first 2 years of the study (1997, 1998) and the last 2 years (2007, 2008) the rate of in-patient suicide fell by nearly one-third from 2.45 to 1.68 per 100 000 bed days. This fall in rate was observed for males and females, across ethnicities and diagnoses. It was most marked for patients aged 15–44 years. Rates also fell for the most common suicide methods, particularly suicide by hanging on the ward (a 59% reduction). Although the number of post-discharge suicides fell, the rate of post-discharge suicide may have increased by 19%. The number of suicide deaths in those under the care of crisis resolution/home treatment teams has increased in recent years to approximately 160 annually.
The rate of suicide among psychiatric in-patients in England has fallen considerably. Possible explanations include falling general population rates, changes in the at-risk population or improved in-patient safety. However, a transfer of risk to the period after discharge or other clinical settings such as crisis resolution teams cannot be ruled out.
Risk for post-traumatic stress disorder (PTSD) varies in part due to the nature of the traumatic event involved. Both injury and return from combat pose high risk of PTSD symptoms. How different injuries may predispose towards PTSD is less well understood.
A retrospective record review was conducted from 1402 service members who had returned to Naval Medical Center San Diego from Iraq or Afghanistan and who had completed the PTSD Checklist as part of their post-deployment screening. Rates of PTSD were examined in relation to mechanism of injury.
Of those without injury, 8% met Diagnostic and Statistical Manual criteria for PTSD. Thirteen percent of those with a penetrating injury, 29% with blunt trauma, and 33% with combination injuries met criteria for PTSD. PTSD severity scores varied significantly according to type of injury.
The World War I concept of “shell shock” implied that blast-related injuries were more likely to result in psychological symptoms than were other injuries. These data may support that idea. Circumstance of injury, population differences, and reporting bias could also have influenced the results.
These results suggest that service members with blunt or combination injuries merit particular attention when screening for PTSD.
Self-harm is a common reason for Emergency Department (ED) attendance. We aimed to develop a clinical tool to help identify patients at higher risk of repeat self-harm, or suicide, within 6 months of an ED self-harm presentation.
The tool, the ReACT Self-Harm Rule, was derived using multicentre data from a prospective cohort study. Binary recursive partitioning was applied to data from two centres, and data from a separate centre were used to test the tool. There were 29 571 self-harm presentations to five hospital EDs between January 2003 and June 2007, involving 18 680 adults aged ⩾16 years. We estimated sensitivity, specificity and positive and negative predictive values to measure the performance of the tool.
A self-harm presentation was classified as higher risk if at least one of the following factors was present: recent self-harm (in the past year), living alone or homelessness, cutting as a method of harm and treatment for a current psychiatric disorder. The rule performed with 95% sensitivity [95% confidence interval (CI) 94–95] and 21% specificity (95% CI 21–22), and had a positive predictive value of 30% (95% CI 30–31) and a negative predictive value of 91% (95% CI 90–92) in the derivation centres; it identified 83/92 of all subsequent suicides.
The ReACT Self-Harm Rule might be used as a screening tool to inform the process of assessing self-harm presentations to ED. The four risk factors could also be used as an adjunct to in-depth psychosocial assessment to help guide risk formulation. The use of multicentre data helped to maximize the generalizability of the tool, but we need to further verify its external validity in other localities.
It is shown that three independent axioms uniquely determine the topological degree of set-valued maps of the form I – G, where G is a convex-valued, limit compact map. This extends earlier work of Amann and Weiss, Nussbaum, and others, in that, apart from dealing with set-valued maps, a larger class of maps is considered even in the single-valued case.