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Initial Conditions for Star Formation: A Physical Description of the Filamentary ISM
No full textThe interstellar medium contains filamentary structure over a wide range of scales. Understanding the role of this structure, both as a conduit of gas across the scales and a diagnostic tool of local physics, is a major focus of star formation studies. We review recent progress in studying filamentary structure in the ISM, interpreting its properties in terms of physical processes, andexploring formation and evolution scenarios. We include structures from galactic-scale filaments to tenth-of-a-parsec scale filaments, comprising both molecular and atomic structures, from both observational and theoretical perspectives. In addition to the literature overview, we assemble a large amount of catalogue data from different surveys and provide the most comprehensive census of filamentary structures to date. Our census consists of 22 803 filamentary structures, facilitating a holistic perspective and new insights. We use our census to conduct a meta-analysis, leading to a description of filament properties over four orders of magnitudes in length and eight in mass. Our analysis emphasises the hierarchical and dynamical nature of filamentary structures. Filaments do not live in isolation, nor they generally resemble static structures close to equilibrium. We propose that accretion during filament formation and evolution sets some of the key scaling properties of filaments. This highlights the role of accretion during filament formation and evolution and also in setting the initial conditions for star formation. Overall, the study of filamentary structures during the past decade has been observationally driven. While great progress has been made on measuring the basic properties of filaments, our understanding of their formation and evolution is clearly lacking. In this context, we identify a number of directions and questions we consider most pressing for the field
Expensive Optimization with Production-Graph Resource Constraints: A First Look at a New Problem Class
No full textWe consider a new class of expensive, resource-constrained optimization problems (here arising from molecular discovery) where costs are associated with the experiments (or evaluations) to be carried out during the optimization process. In the molecular discovery problem, candidate compounds to be optimized must be synthesized in an iterative process that starts from a set of purchasable items and builds up to larger molecules. To produce target molecules, their required resources are either used from alreadysynthesized items in storage or produced themselves on-demand at an additional cost. Any remaining resources from the production process are stored for reuse for the next evaluations.We model these resource dependencies with a directed acyclic production graph describing the development process from granular purchasableitems to evaluable target compounds. Moreover, we develop several resource-efficient algorithms to address this problem. In particular, we develop resource-aware variants of Random Search heuristics and of Bayesian Optimization and analyze their performance in terms of anytime behavior. The experimental results were obtained from a real-world molecular optimization problem. Our results suggest that algorithms that encourage exploitation by reusing existing resources achieve satisfactory results while using fewer resources overall.CCS CONCEPTS• Theory of computation→Random search heuristics; • Mathematics of computing→Probabilistic algorithms.KEYWORDSmolecular discovery, production costs, resource constraints, expensive optimization<br/
ESBMC-Jimple: Verifying Kotlin Programs via Jimple Intermediate Representation
No full textIn this work, we describe and evaluate the first model checker for verifying Kotlin programs through the Jimple intermediate representation. The verifier, named ESBMC-Jimple, is built on top of the Efficient SMT-based Context-Bounded Model Checker (ESBMC). It uses the Soot framework to obtain the Jimple IR, representing a simplified version of the Kotlin source code, containing a maximum of three operands per instruction. ESBMC-Jimple processes Kotlin source code together with a model of the standard Kotlin libraries and checks a set of safety properties. Experimental results show that ESBMC-Jimple can correctly verify a set of Kotlin benchmarks from the literature and that it is competitive with state-of-theart Java bytecode verifiers. A demonstration is available at https://youtu.be/J6WhNfXvJNc
Staff training to improve participant recruitment into surgical randomised controlled trials: a feasibility Study Within A Trial (SWAT) across four host randomised controlled trials simultaneously
No full textObjectiveTo test the feasibility of undertaking a simultaneous Study Within A Trial (SWAT) to train staff who recruit participants into surgical randomised controlled trials (RCTs), by assessing key uncertainties around recruitment, randomisation, intervention delivery and data collection. Study design and settingTwelve surgical RCTs were eligible. Interested sites (clusters) were randomised 1:1, with recruiting staff (surgeons and nurses) offered training or no training. The primary outcome was the feasibility of recruiting sites across multiple surgical trials simultaneously. Secondary outcomes included numbers/types of staff enrolled, attendance at training, training acceptability, confidence in recruiting and participant recruitment rates six months later. ResultsFour RCTs (33%) comprising 91 sites participated. Of these, 29 sites agreed to participate (32%) and were randomised to intervention (15 sites, 29 staff) or control (14 sites, 29 staff). Research nurses attended and found the training to be acceptable; no surgeons attended. In the intervention group, there was evidence of increased confidence when pre and post training scores were compared (mean difference in change 1.42; 95% CI 0.56, 2.27; p = 0.002) – there was no effect on recruitment rate. ConclusionIt was feasible to randomise sites across four surgical RCTs in a simultaneous SWAT design. However, as small numbers of trials and sites participated, and no surgeons attended training, strategies to improve these aspects are needed for future evaluations. Trial registrationISRCTN registry: DISC (ISRCTN18254597), registered on 4th April 2017; PROFHER 2 (ISRCTN76296703), registered on 5th April 2018; IntAct (ISRCTN13334746), registered on 10th April 2017; and START:REACTS (ISRCTN17825590), registered on 5th March 2018. The training SWAT has been submitted to the MRC SWAT repository (SWAT111) <br/
Dynamics of electrostatic interaction and electrodiffusion in a charged thin film with nanoscale physicochemical heterogeneity: implications for low-salinity waterflooding
No full textThe slow kinetics of wettability alteration toward a more water-wetting state by low-salinity waterflooding (LSWF) in oil-brine-rock (OBR) systems is conjectured to be pertinent to the electrokinetic phenomena in the thin brine film. We hypothesize that the nanoscale physicochemical heterogeneities such as surface roughness and surface charge heterogeneity at the rock/brine interface control further the dynamics of electrodiffusion and electrostatic disjoining pressure (Πel), thus the time-scale and the magnitude of the low salinity effect (LSE). Film-scale computational fluid dynamics (CFD) simulations were performed to demonstrate this. The coupled Poisson-Nernst-Planck (PNP) equations were solved numerically in a thin water film confined between a solid surface and oil, both negatively charged. The solid surface is representative of quartz/kaolinite with patchwise physicochemical heterogeneity. The electrical properties of the oil are representative of a crude-oil sample. The OBR system is initially under chemical equilibrium with high salinity (HS) brine, then is exposed to low salinity (LS) brine. The time-scale of reaching chemical equilibrium under LS, and the evolution of electric potential were investigated. We find that surface roughness increases the diffusion time up to 3-fold due to increased tortuosity. Also, the effect of surface roughness and surface charge heterogeneity on the effective diffusioncoefficient (Deff) is minor. While surface roughness and surface charge 1 heterogeneity affect the disjoining pressure (Πel) significantly, the influence of surface roughness on Πel is more pronounced under HS than LS conditions. In contrast, the effect of surface charge heterogeneity (introduced by kaolinite patches on quartz) is more appreciable under LS than HS. Our findings imply that the LS effect can be enhanced in rough, heterogeneously charged systems like clayey sandstone, although its magnitude depends on the charge density of the roughness. We introduce two scaling factors, namely the effective diffusion coefficient (Deff) and the retardation coefficient (ω), to upscale the nanoscale results to pore-scale and beyond
The Effect of Compositional Heterogeneity on the Martensite Start Temperature of a High Strength Steel During Rapid Austenitisation and Cooling
No full textMany low alloy steels are compositionally heterogeneous due to the preferential segregation of alloying elements to the dendritic or interdendritic regions when the steel is first solidified (microsegregation). This segregation is often ignored when using CCT diagrams to predict the phase transformation behaviour of steels, but may be of importance in some industrially-relevant cases. This work focuses on the martensite start temperature (Ms) of Super CMV, a high strength aerospace steel, after rapid austenitisation treatment to various peak temperatures from 900 °C to 1300 °C. It was found that the average Ms temperature increased with increasing peak temperature (and prior austenite grain size) at peak temperatures of 1100°C and above, which is to be expected conventionally. However, at peak temperatures of below 1100°C, the Ms temperature increased with decreasing prior-austenite grain size. It is proposed that this was due to the presence of non-dissolved carbides in these conditions, particularly in enriched bands of material, which deplete the matrix and hence raise Ms
Hypnotic suggestibility in dissociative and related disorders: A meta-analysis
No full textElevated responsiveness to verbal suggestions is hypothesized to represent a predisposing factor for dissociative disorders (DDs) and related conditions. However, the magnitude of this effect has not been estimated in these populations nor has the potential moderating influence of methodological limitations on effect size variability across studies. This study assessed whether patients with DDs, trauma- and stressor-related disorders (TSDs), and functional neurological disorder (FND) display elevated hypnotic suggestibility. A systematic literature search identified 20 datasets. A random-effects meta-analysis revealed that patients displayed greater hypnotic suggestibility than controls, Hedges’s g=0.92 [0.66, 1.18]. This effect was observed in all subgroups but was most pronounced in the DDs. Although there was some evidence for publication bias, a bias-corrected estimate of the group effect remained significant, g=0.57 [0.30, 0.85]. Moderation analyses did not yield evidence for a link between effect sizes and methodological limitations. These results demonstrate that DDs and related conditions are characterized by elevated hypnotic suggestibility and have implications for the mechanisms, risk factors, and treatment of dissociative psychopathology. Keywords: dissociation; hypnotizability; post-traumatic stress disorder; suggestion; trauma<br/
“My life isn't my life, it's the system’s”: A qualitative exploration of women’s experiences of day-to-day restrictive practices as inpatients
No full textIntroductionInpatient care often involves restrictive interventions such as seclusion and restraint and restrictive practices that limit the person’s freedom, rights, and daily activities. Restrictive practice has not been the explicit focus in previous research however, it often appears as an important theme, with participants identifying it can have a detrimental effect on their wellbeing. More research specifically on this topic in an inpatient setting is therefore needed. Women might be particularly vulnerable to adverse effects of restrictive practices compared to men as women generally occupy less powerful positions in society and more often experience abuse. AimsThe study aimed to explore women’s experiences of routine restrictive practices in mental health inpatient settings. MethodsTwenty-two women who were currently inpatients on mental health wards were interviewed about their experiences of restrictive practices in hospital. Interviews were analysed using thematic analysis. ResultsAn overarching theme emerged of powerlessness. Four key subthemes were also identified: restrictions perceived as punitive, having no voice, impact of restrictions on relationships, and restrictions providing safety and support. DiscussionAlthough restrictive practices were found to provide the women with a sense of safety, they were also found to impact upon the women’s well-being, leading to increases in self-harm and over-reliance on restrictions. Implications for practiceThis research highlights the importance of gender-informed inpatient services for women that foster independence, empowerment and allow women to have their voices heard. Safewards interventions such as clear mutual expectations and soft words could contribute to mitigating the impact of restrictive practices
Do we need audiogram-based prescriptions? A systematic review.
No full textOBJECTIVE: Hearing aids are typically programmed using the individual’s audiometric thresholds and verified using real-ear measures. Developments in technology have resulted in a new category of direct-to-consumer devices, which are not necessarily programmed using the individual’s audiometric thresholds. This review aimed to identify whether programming hearing aids using the individual’s validated audiogram-based prescription, and verified using real-ear measures, results in better outcomes for adults with hearing loss.DESIGN: The review was registered in PROSPERO and reported in accordance with PRISMA guidelines.STUDY SAMPLE: After screening more than 1,370 records, seven experimental studies met the eligibility criteria.RESULTS: Studies were categorised under three methods of fitting: (i) comparative fitting evaluating different settings based on the beliefs of the audiologist; (ii) client choice of preset responses; and (iii) self-fit by adjustment. The findings suggest that using a prescription based on the individual’s audiogram improves outcomes relative to the comparative and client choice fitting approaches. Self-adjustment during daily use may produce equivalent (or better) outcomes than an audiogram-based prescription. The quality of evidence for the outcomes ranged from low to very low. CONCLUSIONS: This review has highlighted the dearth of high-quality studies on which to make evidence-based decisions on hearing aid fitting methods. <br/
