Mechanisms of rare events in condensed phases

Chemical reactions, mass transport in solids, protein folding, and nucleation in first-order phase transitions are examples of processes characterized by multiple, long-lived states. Transitions from one (meta)stable state to another are rare and brief, making them difficult to resolve experimentally. And yet the short transition paths contain valuable structural and dynamic information that governs the lifetimes of the stable states. Transition state theory provides a valuable framework for analyzing rare events, provided that an exact dividing surface with no-recrossing can be found. Direct simulation of rare events processes are complicated by the long waiting times for a transition to spontaneously occur. Simulation methods that introduce a bias decrease the waiting time but also risk altering the mechanism. The reactive flux correlation function provides a two-step recipe for computing rates from simulation using an approximate dividing surface, but may miss important details about the physical reaction mechanism. Transition path sampling (TPS) was developed specifically to sample unbiased dynamical reactive trajectories and in combination with likelihood maximization provides an optimized reaction coordinate model. We present new, simple TPS methods that reduce the computational expense of simulating rare events over existing methods. We apply these methods to study rare events in condensed phases and analyze the resulting data with likelihood maximization. The mechanism for vacancy migration in a single domain crystal by activated hops is examined. We find that accurately locating the donor and acceptor sites has a dramatic effect on identifying the mechanism. We next investigate the role of water in ion-pair dissociation, uncovering two solvent mechanisms that influence ion-pair transition states. The resulting dividing surface does not eliminate recrossing, so we present a test for the existence of a no-recrossing surface. It is revealed that an exact dividing surface does not exist for ion-pair dissociation. We discuss the ramifications for transition state theory, Grote-Hynes theory and the relationship between them

Thermal analysis of fin cooling large format automotive lithium-ion pouch cells

Conductively cooling the surface of lithium-ion pouch cells may simplify the external cooling mechanism, as heat transfer mediums are not routed across the cell surface. In this paper, the thermal performance of cooling cells with metallic fins is analysed using a developed test rig and thermal model. Results indicate that single edge fin cooling with aluminum sheets is effective in limiting surface temperature gradients to below circa 5℃ for cells subject to realistic EV and mild PHEV duty cycles. For aggressive track racing EV cycles, double edge fin cooling is required to limit surface temperature gradients to below 12℃

Induction of β-Lactamase Activity and Decreased β-Lactam Susceptibility by CO2 in Clinical Bacterial Isolates

Antimicrobial susceptibility testing of clinical isolates is a crucial step toward appropriate treatment of infectious diseases. The clinical isolate Francisella philomiragia 14IUHPL001, recently isolated from a 63-year-old woman with atypical pneumonia, featured decreased susceptibility to β-lactam antibiotics when cultivated in 5% CO2. Quantitative β-lactamase assays demonstrated a significant (P < 0.0001) increase in enzymatic activity between bacteria cultivated in 5% CO2 over those incubated in ambient air. The presence of β-lactamase genes blaTEM and blaSHV was detected in the clinical isolate F. philomiragia 14IUHPL001 by PCR, and the genes were positively identified by nucleotide sequencing. Expression of blaTEM and blaSHV was detected by reverse transcription-PCR during growth at 5% CO2 but not during growth in ambient air. A statistically significant alkaline shift was observed following cultivation of F. philomiragia 14IUHPL001 in both ambient air and 5% CO2, allowing desegregation of the previously reported effects of acidic pH from the currently reported effect of 5% CO2 on blaTEM and blaSHV β-lactamases. To ensure that the observed phenomenon was not unique to F. philomiragia, we evaluated a clinical isolate of blaTEM-carrying Haemophilus influenzae and found parallel induction of blaTEM gene expression and β-lactamase activity at 5% CO2 relative to ambient air. IMPORTANCE β-Lactamase induction and concurrent β-lactam resistance in respiratory tract pathogens as a consequence of growth in a physiologically relevant level of CO2 are of clinical significance, particularly given the ubiquity of TEM and SHV β-lactamase genes in diverse bacterial pathogens. This is the first report of β-lactamase induction by 5% CO2

The role of the biomechanics analyst in swimming training and competition analysis

Swimming analysts aid coaches and athletes in the decision-making by providing evidence-based recommendations. The aim of this narrative review was to report the best practices of swimming analysts that have been supporting high-performance athletes. It also aims to share how swimming analysts can translate applied research into practice. The role of the swimming analyst, as part of a holistic team supporting high-performance athletes, has been expanding and is needed to be distinguished from the job scope of a swimming researcher. As testing can be time-consuming, analysts must decide what to test and when to conduct the evaluation sessions. Swimming analysts engage in the modelling and forecast of the performance, that in short- and mid-term can help set races target-times, and in the long-term provide insights on talent and career development. Races can be analysed by manual, semi-automatic or fully automatic video analysis with single or multi-cameras set-ups. The qualitative and quantitative analyses of the swim strokes, start, turns, and finish are also part of the analyst job scope and associated with race performance goals. Land-based training is another task that can be assigned to analysts and aims to enhance the performance, prevent musculoskeletal injuries and monitor its risk factors.This project was funded by the FCT - Portuguese Foundation for Science and Technology (UIDB/DTP/04045/2020).info:eu-repo/semantics/publishedVersio

Reaction coordinates, one-dimensional Smoluchowski equations, and a test for dynamical self-consistency

We propose a method for identifying accurate reaction coordinates among a set of trial coordinates. The method applies to special cases where motion along the reaction coordinate follows a one-dimensional Smoluchowski equation. In these cases the reaction coordinate can predict its own short-time dynamical evolution, i.e., the dynamics projected from multiple dimensions onto the reaction coordinate depend only on the reaction coordinate itself. To test whether this property holds, we project an ensemble of short trajectory swarms onto trial coordinates and compare projections of individual swarms to projections of the ensemble of swarms. The comparison, quantified by the Kullback-Leibler divergence, is numerically performed for each isosurface of each trial coordinate. The ensemble of short dynamical trajectories is generated only once by sampling along an initial order parameter. The initial order parameter should separate the reactants and products with a free energy barrier, and distributions on isosurfaces of the initial parameter should be unimodal. The method is illustrated for three model free energy landscapes with anisotropic diffusion. Where exact coordinates can be obtained from Kramers-Langer-Berezhkovskii-Szabo theory, results from the new method agree with the exact results. We also examine characteristics of systems where the proposed method fails. We show how dynamical self-consistency is related (through the Chapman-Kolmogorov equation) to the earlier isocommittor criterion, which is based on longer paths. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4775807

Prioritising patients for bariatric surgery: building public preferences from a discrete choice experiment into public policy

Objectives To derive priority weights for access to bariatric surgery for obese adults, from the perspective of the public. Setting Australian public hospital system. Participants Adults (N=1994), reflecting the age and gender distribution of Queensland and South Australia. Primary and secondary outcome measures A discrete choice experiment in which respondents indicated which of two individuals with different characteristics should be prioritised for surgery in repeated hypothetical choices. Potential surgery recipients were described by seven key characteristics or attributes: body mass index (BMI), presence of comorbid conditions, age, family history, commitment to lifestyle change, time on the surgical wait list and chance of maintaining weight loss following surgery. A multinomial logit model was used to evaluate preferences and derive priority weights (primary analysis), with a latent class model used to explore respondent characteristics that were associated with variation in preference across the sample (see online supplementary analysis). Results A preference was observed to prioritise individuals who demonstrated a strong commitment to maintaining a healthy lifestyle as well as individuals categorised with very severe (BMI≥50 kg/m2) or (to a lesser extent) severe (BMI≥40 kg/m2) obesity, those who already have obesity-related comorbidity, with a family history of obesity, with a greater chance of maintaining weight loss or who had spent a longer time on the wait list. Lifestyle commitment was considered to be more than twice as important as any other criterion. There was little tendency to prioritise according to the age of the recipient. Respondent preferences were dependent on their BMI, previous experience with weight management surgery, current health state and education level. Conclusions This study extends our understanding of the publics’ preferences for priority setting to the context of bariatric surgery, and derives priority weights that could be used to assist bodies responsible for commissioning bariatric services

Quem deveria participar na definição das prioridades em saúde e como deveriam essas prioridades ser estabelecidas? Resultados de um inquérito em Portugal

This research was partially funded by Fundac ̧ão para a Ciên-cia e Tecnologia (FCT) through the Applied MicroeconomicsResearch Unit (NIMA) strategic project with reference PEst-OE/EGE/UI3181/2011This article provides highlights of the evolution of the health care rationing debate towards a more explicit and open approach involving public participation. Discretionary models that have dominated the health sector decision-making are being questioned by different sectors of society. Methods Using data from 442 college students, we explore public views on public involvement in health care rationing decisions. Results Findings suggest that although citizens wish to be consulted, they believe doctors should play the most important role on rationing decisions. Discussion Confidence in doctors is, nonetheless, not independent from the criteria used to support their decisionsIntrodução: Este artigo destaca a evolução do debate sobre o racionamento dos cuidados de saúde com vista a uma aproximação mais explícita e mais aberta que envolva a participação pública. Os modelos arbitrários que dominarama tomada de decisão no setor da saúde estão a ser questionados por diferentes setores da sociedade. Métodos: Partindo de dados recolhidos com 442 estudantes universitário, foram exploradas as opiniões sobre a participação pública no que se refere à tomada de decisão quanto ao racionamento dos cuidados de saúde.Fundação para a Ciência e a Tecnologia (FCT

Characteristics of large Martian dust devils using Mars Odyssey Thermal Emission Imaging System visual and infrared images

A search for Martian dust devils has been carried out, using Mars Odyssey Thermal Emission Imaging System (THEMIS) visible-wavelength images. Simultaneous THEMIS thermal infrared wavelength images were then processed and analyzed to investigate the thermal properties of the dust devils observed; 3079 images were checked, concentrating on northern spring, summer, and autumn (LS from 0° to 270°, 20°S to 50°N). Mars Express High Resolution Stereo Camera, Mars Global Surveyor Mars Orbiter Camera, and other THEMIS visible images were used for comparison to potentially rule out any ambiguous geological features. Eight clear examples of dust devils have been found in five separate images, with a comparable number of unconfirmed possible devils. The rarity of dust devils observed is believed to result from a combination of the difficulty in identifying dust devils in medium resolution THEMIS data and the fact that the Mars Odyssey orbit flyover local time is later in the afternoon than would be optimum for dust devil searching. The temporal distribution of dust devil activity appears to be weighted more toward later afternoon, compared to Earth, but this may be a sampling effect due to size variation with time of sol, greater coverage later in the sol, or the small-number statistics. The thermal infrared images indicate that the lofted dust in the column is cooler than the surrounding surface and must be equilibrating with the atmosphere in the dust devil. This energy transfer is estimated to be about 10% of the heat flux energy that is available to drive the systems. The ground shadowed by the dust column also appears colder than the surroundings, because of reduced solar illumination. From the visible-wavelength images, the shadows of the dust columns were used to estimate the column opacity, which in turn gave estimates of the dust loadings, which ranged from 1.9 × 10?5 to 1.5 × 10?4 kg m?3, similar to lander-based observations. No thermal or visible trails are associated with the dust devils, indicating that the surface equilibrates quickly after the devil has passed and that track counting as a dust devil survey technique must underestimate dust devil populations and consequently dust loading calculations, confirming previous work

Smoking cessation during pregnancy: the influence of partners, family and friends on quitters and non-quitters

This research compared pregnant quitters’ and non-quitters’ accounts of how partners, family and friends influenced their smoking cessation attempts. Qualitative secondary data analysis was carried out on a purposive sample of motivational interview transcripts undertaken by research midwives with pregnant women as part of SmokeChange, a smoking cessation intervention. Interviews with all quitters in the intervention group (n = 12) were analysed comparatively with interviews from a matched sample of non-quitters (n = 12).The discourses of both revealed similarity in how their partners, family and friends influenced their cessation efforts: salient others were simultaneously perceived by both groups of women as providing drivers and barriers to quit attempts; close associates who smoked were often perceived to be as supportive as those who did not. However, women who quit smoking during pregnancy talked more about receiving active praise/encouragement than those who did not. While close associates play an important role in women’s attempts to stop smoking during pregnancy, the support they provide varies; further research is needed to develop a better understanding of how key relationships help or hinder cessation during pregnancy

A systematic review and meta-analysis of factors that relate to aggression perpetrated against nurses by patients/relatives or staff

Aims and objectives- The aim of this meta-analysis was to identify the factors that related to aggression (verbal abuse, or physical abuse/assault) perpetrated against the nurse or other health professional by patients/relatives or staff. In light of the paucity of systematic reviews on this common issue in nursing, the objective was to present a comprehensive systematic review and meta-analysis of these papers. Background – Aggression towards nurses is common around the world and can be the impetus for nurses leaving the profession or developing anxiety when working in particular settings. Design- Systematic review with meta-analysis Data Sources- The databases of Medline (1966 to 2015), CINAHL (1982 to 2015) and PsychInfo (1920 to 2015). Methods- Meta-analyses were conducted to assess the effect of the factors of gender and context (dichotomised as mental health/psychiatric or non-mental health/psychiatric). Results - A total of 1571 papers were screened by two reviewers. At the final decision 14 were selected for analysis. A higher proportion of female nurses than male nurses were reported to be the victims of verbal abuse, with the difference in proportions being statistically significant. A statistically significant higher proportion of male nurses than female nurses were reported to be the victims of physical abuse. There was a significantly higher proportion of mental health nurses reported experiencing physical abuse as compared to non-mental health nurses. Conclusions – The analysis reveal female nurses have greater odds of verbal abuse than male nurses and male nurses have greater odds of physical abuse than female nurses. Overall mental health nurses had 3 times higher odds of physical assault than other nurses. Relevance to clinical practice- In light of the findings it is recommended organisational support improve in high aggression potential clinical areas and for nursing curriculums to incorporate education about the management of challenging behaviours in undergraduate programs