The effect of high lethal temperatures on the muscle of the crayfish, astacus pallipes lereboullet; a biochemical and electrophysiological

The phenomenon of temperature adaptation, as measured by the mobility of the heat death point, was demonstrated in Aatacus pallipes Lereboullet. Analysis of muscle, haemolymph and environment during lethal high temperature exposure showed dramatic Na(^+) and K(^+) concentration changes in all three compartments. In all cases the monovalent cations showed a net movement down their respective electro-chemical gradients, although this was sometimes only observed after a brief initial period during which the ions tended to exhibit a net movement up their electro-chemical gradients. The results indicated that heat death occurred when the haemolymph K(^+) concentration rose to about 9 mM. No relationship between the haemolymph Na(^+) concentration and the heat death point was observed. Electrophysiological experiments indicated that lethal high temperatures caused an increase in the conductivity (-, permeability) of the sarcolemma following comparable exposure times to those causing heat death in the whole animal. The Mg(^++)activated ATPase (EC 3.6.1.3.) which is involved in the control of sarcolemmal permeability was shown to be inactivated by lethal high temperatures. It was therefore concluded that the increased sarcolemmal permeability was caused by the thermal inactivation of this enzyme. The spontaneous activity of the CNS was only slightly affected by exposure to lethal high temperatures. Raising the extracellular K* concentration to the levels observed in animals at the time of heat death caused a massive increase in nervous activity. The sarcolemmal Mg (^++) activated ATPase from warm adapted crayfish was shown to be more resistant to high temperatures than that from cold adapted crayfish. This could be correlated with the greater heat resistance of the sarcolemmal Mg(^++) activated ATPase and conductivity seen in the warm adapted animals. It is proposed that the primary lesion of heat death in Astacus pallipes Lereboullet is the thermal inactivation of the sarcolemmal Mg(^++) activated ATPase which allows muscle K(^+) to move into the haemolymph. The activity of the CNS is increased markedly by the high haemolymph K(^+) resulting in loss of coordination and death. The thermal sensitivity of the Mg(^++) activated ATPase is modified by the previous thermal history of the crayfish and is involved in the mechanism of temperature adaptation

How to construct spin chains with perfect state transfer

It is shown how to systematically construct the $XX$ quantum spin chains with nearest-neighbor interactions that allow perfect state transfer (PST). Sets of orthogonal polynomials (OPs) are in correspondence with such systems. The key observation is that for any admissible one-excitation energy spectrum, the weight function of the associated OPs is uniquely prescribed. This entails the complete characterization of these PST models with the mirror symmetry property arising as a corollary. A simple and efficient algorithm to obtain the corresponding Hamiltonians is presented. A new model connected to a special case of the symmetric $q$-Racah polynomials is offered. It is also explained how additional models with PST can be derived from a parent system by removing energy levels from the one-excitation spectrum of the latter. This is achieved through Christoffel transformations and is also completely constructive in regards to the Hamiltonians.Comment: 7 page

Viewing Nature Scenes Positively Affects Recovery of Autonomic Function Following Acute-Mental Stress

A randomized crossover study explored whether viewing different scenes prior to a stressor altered autonomic function during the recovery from the stressor. The two scenes were (a) nature (composed of trees, grass, fields) or (b) built (composed of man-made, urban scenes lacking natural characteristics) environments. Autonomic function was assessed using noninvasive techniques of heart rate variability; in particular, time domain analyses evaluated parasympathetic activity, using root-mean-square of successive differences (RMSSD). During stress, secondary cardiovascular markers (heart rate, systolic and diastolic blood pressure) showed significant increases from baseline which did not differ between the two viewing conditions. Parasympathetic activity, however, was significantly higher in recovery following the stressor in the viewing scenes of nature condition compared to viewing scenes depicting built environments (RMSSD; 50.0 ± 31.3 vs 34.8 ± 14.8 ms). Thus, viewing nature scenes prior to a stressor alters autonomic activity in the recovery period. The secondary aim was to examine autonomic function during viewing of the two scenes. Standard deviation of R-R intervals (SDRR), as change from baseline, during the first 5 min of viewing nature scenes was greater than during built scenes. Overall, this suggests that nature can elicit improvements in the recovery process following a stressor. © 2013 American Chemical Society

Adhesive Contact to a Coated Elastic Substrate

We show how the quasi-analytic method developed to solve linear elastic contacts to coated substrates (Perriot A. and Barthel E. {\em J. Mat. Res.}, {\bf 2004}, {\em 19}, 600) may be extended to adhesive contacts. Substrate inhomogeneity lifts accidental degeneracies and highlights the general structure of the adhesive contact theory. We explicit the variation of the contact variables due to substrate inhomogeneity. The relation to other approaches based on Finite Element analysis is discussed

Walks4work: Rationale and study design to investigate walking at lunchtime in the workplace setting

Background: Following recruitment of a private sector company, an 8week lunchtime walking intervention was implemented to examine the effect of the intervention on modifiable cardiovascular disease risk factors, and further to see if walking environment had any further effect on the cardiovascular disease risk factors. Methods. For phase 1 of the study participants were divided into three groups, two lunchtime walking intervention groups to walk around either an urban or natural environment twice a week during their lunch break over an 8week period. The third group was a waiting-list control who would be invited to join the walking groups after phase 1. In phase 2 all participants were encouraged to walk during their lunch break on self-selecting routes. Health checks were completed at baseline, end of phase 1 and end of phase 2 in order to measure the impact of the intervention on cardiovascular disease risk. The primary outcome variables of heart rate and heart rate variability were measured to assess autonomic function associated with cardiovascular disease. Secondary outcome variables (Body mass index, blood pressure, fitness, autonomic response to a stressor) related to cardiovascular disease were also measured. The efficacy of the intervention in increasing physical activity was objectively monitored throughout the 8-weeks using an accelerometer device. Discussion. The results of this study will help in developing interventions with low researcher input with high participant output that may be implemented in the workplace. If effective, this study will highlight the contribution that natural environments can make in the reduction of modifiable cardiovascular disease risk factors within the workplace. © 2012 Brown et al.; licensee BioMed Central Ltd

Tipping Points in 1-dimensional Schelling Models with Switching Agents

Schelling’s spacial proximity model was an early agent-based model, illustrating how ethnic segregation can emerge, unwanted, from the actions of citizens acting according to individual local preferences. Here a 1-dimensional unperturbed variant is studied under switching agent dynamics, interpretable as being open in that agents may enter and exit the model. Following the authors’ work (Barmpalias et al., FOCS, 2014) and that of Brandt et al. (Proceedings of the 44th ACM Symposium on Theory of Computing (STOC 2012), 2012), rigorous asymptotic results are established. The dynamic allows either type to take over almost everywhere. Tipping points are identified between the regions of takeover and staticity. In a generalization of the models considered in [1] and [3], the model’s parameters comprise the initial proportions of the two types, along with independent values of the tolerance for each type. This model comprises a 1-dimensional spin-1 model with spin dependent external field, as well as providing an example of cascading behaviour within a network

Professionalism, Golf Coaching and a Master of Science Degree: A commentary

As a point of reference I congratulate Simon Jenkins on tackling the issue of professionalism in coaching. As he points out coaching is not a profession, but this does not mean that coaching would not benefit from going through a professionalization process. As things stand I find that the stimulus article unpacks some critically important issues of professionalism, broadly within the context of golf coaching. However, I am not sure enough is made of understanding what professional (golf) coaching actually is nor how the development of a professional golf coach can be facilitated by a Master of Science Degree (M.Sc.). I will focus my commentary on these two issues

R and Shiny for cost-effectiveness analyses : why and when? A hypothetical case study

Introduction Health economics models are typically built in Microsoft Excel® owing to its wide familiarity, accessibility and perceived transparency. However, given the increasingly rapid and analytically complex decision-making needs of both the pharmaceutical industry and the field of health economics and outcomes research (HEOR), the demands of cost-effectiveness analyses may be better met by the programming language R. Objective This case study provides an explicit comparison between Excel and R for contemporary cost-effectiveness analysis. Methods We constructed duplicate cost-effectiveness models using Excel and R (with a user interface built using the Shiny package) to address a hypothetical case study typical of contemporary health technology assessment. Results We compared R and Excel versions of the same model design to determine the advantages and limitations of the modelling platforms in terms of (i) analytical capability, (ii) data safety, (iii) building considerations, (iv) usability for technical and non-technical users and (v) model adaptability. Conclusions The findings of this explicit comparison are used to produce recommendations for when R might be more suitable than Excel in contemporary cost-effectiveness analyses. We conclude that selection of appropriate modelling software needs to consider case-by-case modelling requirements, particularly (i) intended audience, (ii) complexity of analysis, (iii) nature and frequency of updates and (iv) anticipated model run time

Qualitative perspectives on how Manchester United Football Club developed and sustained serial winning

Talent development in sport is well represented in scientific literature. Yet, the drive to protect ‘trade secrets’ often means that access to these high performing groups is rare, especially as these high level performances are being delivered. This leaves the details of high-end working practices absent from current academic commentary. As a result, clubs interested in developing excellent practice are left to build on personal initiative and insight and/or custom-and-practice, which is unlikely to yield successful outcomes. To address this shortfall the current study reports on prolonged engagement with a single high performing club, considering how their practice corresponds with existing sport talent development models. The paper ends by proposing an evidence-based, football-specific model for talent development, maintained high level performance and serial winning. This model emphasises four dominant features: culture, behavioral characteristics, practice engagement and the managing and guiding of performance ‘potential’. The study provides insights into the visceral reality of daily experiences across the life course of professional soccer, while advancing the evidence-base for understanding how Manchester United achieved their serial success

The Rationality of Prejudices

We model an -player repeated prisoner's dilemma in which players are given traits (e.g., height, age, wealth) which, we assume, affect their behavior. The relationship between traits and behavior is unknown to other players. We then analyze the performance of “prejudiced” strategies—strategies that draw inferences based on the observation of some or all of these traits, and extrapolate the inferred behavior to other carriers of these traits. Such prejudiced strategies have the advantage of learning rapidly, and hence of being well adapted to rapidly changing conditions that might result, for example, from high migration or birth rates. We find that they perform remarkably well, and even systematically outperform both Tit-For-Tat and ALLD when the population changes rapidly