The effect of metapopulation processes on the spatial scale of adaptation across an environmental gradient

We show that the butterfly Aricia agestis (Lycaenidae) is adapted to its thermal environment in via integer changes in the numbers of generations per year (voltinism): it has two generations per year in warm habitats and one generation per year in cool habitats in north Wales (UK). Voltinism is an “adaptive peak” since individuals having an intermediate number of generations per year would fail to survive the winter, and indeed no populations showed both voltinism types in nature. In spite of this general pattern, 11% of populations apparently possess the “wrong” voltinism for their local environment, and population densities were lower in thermally intermediate habitat patches. Population dynamic data and patterns of genetic differentiation suggest that adaptation occurs at the metapopulation level, with local populations possessing the voltinism type appropriate for the commonest habitat type within each population network. When populations and groups of populations go extinct, they tend to be replaced by colonists from the commonest thermal environment nearby, even if this is the locally incorrect adaptation. Our results illustrate how stochastic population turnover can impose a limit on local adaptation over distances many times larger than predicted on the basis of normal dispersal movements

Genetic Assimilation and Canalisation in the Baldwin Effect

The Baldwin Effect indicates that individually learned behaviours acquired during an organism’s lifetime can influence the evolutionary path taken by a population, without any direct Lamarckian transfer of traits from phenotype to genotype. Several computational studies modelling this effect have included complications that restrict its applicability. Here we present a simplified model that is used to reveal the essential mechanisms and highlight several conceptual issues that have not been clearly defined in prior literature. In particular, we suggest that canalisation and genetic assimilation, often conflated in previous studies, are separate concepts and the former is actually not required for non-heritable phenotypic variation to guide genetic variation. Additionally, learning, often considered to be essential for the Baldwin Effect, can be replaced with a more general phenotypic plasticity model. These simplifications potentially permit the Baldwin Effect to operate in much more general circumstances

Pulse transit time measured by photoplethysmography improves the accuracy of heart rate as a surrogate measure of cardiac output, stroke volume and oxygen uptake in response to graded exercise

Heart rate (HR) is a valuable and widespread measure for physical training programs, although its description of conditioning is limited to the cardiac response to exercise. More comprehensive measures of exercise adaptation include cardiac output ((Q) over dot), stroke volume (SV) and oxygen uptake ((V) over dotO(2)), but these physiological parameters can be measured only with cumbersome equipment installed in clinical settings. In this work, we explore the ability of pulse transit time (PTT) to represent a valuable pairing with HR for indirectly estimating (Q) over dot, SV and (V) over dotO(2) non-invasively. PTT was measured as the time interval between the peak of the electrocardiographic (ECG) R-wave and the onset of the photoplethysmography (PPG) waveform at the periphery (i.e. fingertip) with a portable sensor. Fifteen healthy young subjects underwent a graded incremental cycling protocol after which HR and PTT were correlated with (Q) over dot, SV and (V) over dotO(2) using linear mixed models. The addition of PTT significantly improved the modeling of (Q) over dot, SV and (V) over dotO(2) at the individual level (R-1(2) = 0.419 for SV, 0.548 for (Q) over dot, and 0.771 for (V) over dotO(2)) compared to predictive models based solely on HR (R-1(2) = 0.379 for SV, 0.503 for (Q) over dot, and 0.745 for (V) over dotO(2)). While challenges in sensitivity and artifact rejection exist, combining PTT with HR holds potential for development of novel wearable sensors that provide exercise assessment largely superior to HR monitors

Academic chartered data safety committees versus industry sponsored data safety committees: The need for different recommendations

Dear Editor, We read with great interest the recently published paper by Calis et al.1 We applaud the authors and the working group for developing this important set of recommendations for data monitoring committees (DMC). Recommendations for organizing a DMC are long overdue. Our academic institution has had a formal DMC for many years which administratively reports to an academic official who directs the research efforts. It has a formal charter and broad membership that includes clinicians, clinical trial specialists, and a biostatistician. It accepts for review studies that require a DMC (usually phase II or III trials) and are not sponsored by industry, which usually set up their own DMC. Most studies are supported by the institution, US Government research funding sources (e.g. National Institutes of Health (NIH), Centers for Disease Control and Prevention), or research foundations

Drainage behavior of sports pitches–A case study review

The drainage behavior of sports pitches has traditionally been designed from experience with hydraulic performance rarely measured in detail. Within the wider industry and regulatory bodies there is a perception that storm water and increased drainage rates from sports pitches contribute to local flood risk. Empirical observations have suggested that in reality pitch drainage systems may discharge water at low volumes and rates and there is often limited surface run-off. Furthermore it appears that lack of technical guidance on the discharge of water from sport pitch drainage systems may have led to misunderstanding their drainage behavior and possible benefits they could bring to water management as opposed to perceived dis-benefits. This paper summarizes selected results of a case study which included field measurements of weather and discharge behavior on a range of natural turf sports pitches in England. The findings from this study indicate that natural turf sports pitches can provide resistance to flow and hence advantageous attenuation of rainfall and storm water. Additionally sports pitches can store large volumes of water within the pervious materials used in their design. The study has confirmed that sport pitches demonstrate the key functions that are reflected in the design requirements of Sustainable Urban Drainage Systems (SuDs) such as pervious pavements providing source control of surface rain water

Pretreatment with beta-blockers and the frequency of hypokalemia in patients with acute chest pain

Plasma potassium concentration was measured at admission in 1234 patients who presented with acute chest pain. One hundred and ninety five patients were on P blockers before admission. The potassium concentrations of patients admitted early (within four hours of onsetof symptoms) were compared with those admitted later (4-18 hours after onset of symptoms). There was a transient fall in plasma potassium concentrations in patients not pre-treated with , B blockers. This was not seen in patients who had been on P blockers before admission. Nonselective, B blockers were more effective than cardioselective agents in maintaining concentrationsof plasma potassium. These findings suggest a mechanism for the beneficial effects of ,B blockers on morbidity and mortality in acute myocardial infarction

Classifying medical histories in US medicare beneficiaries using fixed vs all‐available look‐back approaches

Purpose: Evaluate use of fixed and all‐available look‐backs to identify eligibility criteria and confounders among Medicare beneficiaries. Methods: We identified outpatient visits (2007‐2012) with recently documented (≤180 days) cardiovascular risk and classified patients according to whether the exposure (statin) was initiated within 14 days. We selected each beneficiary's first eligible visit (in each treatment group) that met criteria during the respective look‐backs: continuous enrollment (1 or 3 years for fixed look‐back; 180 days for all‐available), no cancer history, and no statin claims. We estimated crude and standardized mortality ratio weighted hazard ratios (HRs) for the effect of statin initiation on incident 6‐month cancer (a known null effect) and 2‐year mortality, separately, adjusting for covariates assessed by using each look‐back. Results: Analyzing short‐term cancer, the estimated HR from the all‐available approach (HR = 0.90, 95% CI: 0.83, 0.98) was less biased than the 1‐year look‐back (HR = 0.79, 95% CI: 0.73, 0.84), which included beneficiaries with prevalent cancer. The 3‐year look‐back (HR = 1.05, 95% CI: 0.90, 1.21) was somewhat less biased than the all‐available estimate but less precise due the exclusion of a large proportion of observations without sufficient continuous enrollment (62.0% and 59.9% of initiators and non‐initiators, respectively). All approaches produced similar estimates of the effect on all‐cause mortality. Alternative look‐backs did not differ in their ability to control confounding. Conclusions: The all‐available look‐back performed nearly as well as the 3‐year fixed, which produced the least biased point estimate. If 3‐year look‐backs are infeasible (eg, due to power/sample), all‐available look‐backs may be preferable to short (1‐year) fixed look‐backs