Conformational dynamics and internal friction in homopolymer globules: equilibrium vs. non-equilibrium simulations

We study the conformational dynamics within homopolymer globules by solvent-implicit Brownian dynamics simulations. A strong dependence of the internal chain dynamics on the Lennard-Jones cohesion strength ε and the globule size N [subscript G] is observed. We find two distinct dynamical regimes: a liquid-like regime (for ε ε[subscript s] with slow internal dynamics. The cohesion strength ε[subscript s] of this freezing transition depends on N G . Equilibrium simulations, where we investigate the diffusional chain dynamics within the globule, are compared with non-equilibrium simulations, where we unfold the globule by pulling the chain ends with prescribed velocity (encompassing low enough velocities so that the linear-response, viscous regime is reached). From both simulation protocols we derive the internal viscosity within the globule. In the liquid-like regime the internal friction increases continuously with ε and scales extensive in N [subscript G] . This suggests an internal friction scenario where the entire chain (or an extensive fraction thereof) takes part in conformational reorganization of the globular structure.American Society for Engineering Education. National Defense Science and Engineering Graduate Fellowshi

The evolution of language: a comparative review

For many years the evolution of language has been seen as a disreputable topic, mired in fanciful "just so stories" about language origins. However, in the last decade a new synthesis of modern linguistics, cognitive neuroscience and neo-Darwinian evolutionary theory has begun to make important contributions to our understanding of the biology and evolution of language. I review some of this recent progress, focusing on the value of the comparative method, which uses data from animal species to draw inferences about language evolution. Discussing speech first, I show how data concerning a wide variety of species, from monkeys to birds, can increase our understanding of the anatomical and neural mechanisms underlying human spoken language, and how bird and whale song provide insights into the ultimate evolutionary function of language. I discuss the ‘‘descended larynx’ ’ of humans, a peculiar adaptation for speech that has received much attention in the past, which despite earlier claims is not uniquely human. Then I will turn to the neural mechanisms underlying spoken language, pointing out the difficulties animals apparently experience in perceiving hierarchical structure in sounds, and stressing the importance of vocal imitation in the evolution of a spoken language. Turning to ultimate function, I suggest that communication among kin (especially between parents and offspring) played a crucial but neglected role in driving language evolution. Finally, I briefly discuss phylogeny, discussing hypotheses that offer plausible routes to human language from a non-linguistic chimp-like ancestor. I conclude that comparative data from living animals will be key to developing a richer, more interdisciplinary understanding of our most distinctively human trait: language

New insights into the genetic etiology of Alzheimer's disease and related dementias

Characterization of the genetic landscape of Alzheimer's disease (AD) and related dementias (ADD) provides a unique opportunity for a better understanding of the associated pathophysiological processes. We performed a two-stage genome-wide association study totaling 111,326 clinically diagnosed/'proxy' AD cases and 677,663 controls. We found 75 risk loci, of which 42 were new at the time of analysis. Pathway enrichment analyses confirmed the involvement of amyloid/tau pathways and highlighted microglia implication. Gene prioritization in the new loci identified 31 genes that were suggestive of new genetically associated processes, including the tumor necrosis factor alpha pathway through the linear ubiquitin chain assembly complex. We also built a new genetic risk score associated with the risk of future AD/dementia or progression from mild cognitive impairment to AD/dementia. The improvement in prediction led to a 1.6- to 1.9-fold increase in AD risk from the lowest to the highest decile, in addition to effects of age and the APOE ε4 allele

Do Nurses Use Discourse Markers Differently when Using Their Second Language as Opposed to Their First while Interviewing Patients?

This study examined whether discourse-marker use changes in nurse-patient interactions as a function of nurses using their first (L1) or second (L2) language. Discourse markers were analyzed as turn-maintenance markers that indicate acknowledgement and discourse-shift markers that signal shifts of a topic or speaker in the conversation. These two categories differ in terms of degree of discourse management and interactional control. Sixteen nurses conducted a pain-assessment interview with a patient native speaker of English and with a patient native speaker of French, where the nurses used their own L1 in one case and their own weaker L2 in the other. The first hypothesis, that nurses would generally use discourse markers more frequently in the L1 than in the L2, was not supported. The second hypothesis, that nurses would use discourse-shift markers less frequently in their L2 compared to the L1, relative to their (baseline) use of turn-maintenance markers, was supported. The findings, especially the support for the second hypothesis, could have implications for the development of L2 training for health practitioners.</p

Factors Associated with Revision Surgery after Internal Fixation of Hip Fractures

Background: Femoral neck fractures are associated with high rates of revision surgery after management with internal fixation. Using data from the Fixation using Alternative Implants for the Treatment of Hip fractures (FAITH) trial evaluating methods of internal fixation in patients with femoral neck fractures, we investigated associations between baseline and surgical factors and the need for revision surgery to promote healing, relieve pain, treat infection or improve function over 24 months postsurgery. Additionally, we investigated factors associated with (1) hardware removal and (2) implant exchange from cancellous screws (CS) or sliding hip screw (SHS) to total hip arthroplasty, hemiarthroplasty, or another internal fixation device. Methods: We identified 15 potential factors a priori that may be associated with revision surgery, 7 with hardware removal, and 14 with implant exchange. We used multivariable Cox proportional hazards analyses in our investigation. Results: Factors associated with increased risk of revision surgery included: female sex, [hazard ratio (HR) 1.79, 95% confidence interval (CI) 1.25-2.50; P = 0.001], higher body mass index (fo

Women’s preferences for masculinity in male faces are predicted by pathogen disgust, but not moral or sexual disgust

Because women's preferences for male masculinity reflect tradeoffs between indirect benefits of greater genetic health and direct costs of lower paternal investment, variables that affect the importance of these costs and benefits also affect masculinity preferences. Concern about disease and pathogens may be one such variable. Here we show that disgust sensitivity in the pathogen domain is positively correlated with facial masculinity preferences, but disgust sensitivity in the moral and sexual domains are not. Our findings present novel evidence that systematic variation in women's preferences for masculine men reflects factors that influence how women resolve the tradeoff between the indirect benefits and the direct costs associated with choosing a masculine partner

Sex differences and sex similarities in disgust sensitivity

Across two studies, we test for sex differences in the factor structure, factor loadings, concurrent validity, and means of the Three Domain Disgust Scale. In Study 1, we find that the Three Domain Disgust Scale has indistinguishable factor structure and factor loadings for men and women. In Study 2, we find a small sex difference in sensitivity to pathogen and moral disgust and a large sex difference in sensitivity to sexual disgust, with women more sensitive to disgust across domains. However, correlations between Three Domain Disgust Scale factors and the five factors and 30 facets of the NEO Personality Inventory were indistinguishable between the sexes. These findings suggest that, despite mean sex differences in disgust sensitivity, the Three Domain Disgust Scale measures similar constructs in men and women. Implications for understanding the constructs measured by the Three Domain Disgust Scale are discussed. © 2011 Elsevier Ltd

Liver resection in octogenarians

Background. Liver resections are increasingly being perfomed safely in elderly patients. There are no present reports of thje operative safety of liver resection in octogenarians who represents a rapidly increasing segment of the population. The purpose of this study was to analyse the results of liver resection in octogenarians over a 5 year period within a tertiary referral liver surgery unit. Methods. Prospective data collection and analysis of octogenarians having liver resection between 1999 and 2004. Retrospective detailed case note analysis was performed to determine peri-operative mortality and morbidity. Comparison were made to other large series of liver resection in younger patient cohorts. The primary outcome measure was 30 day mortality and secondarily a detailed analysis of post-operative complications was performed. Results. A total 15 octogenarians (median age 82) were identified from the database. Ther was 1 peri-operative mortality. The remaining patients were all alive at 1, 3 and 6 month follow-ups with a median follow-up of 18 months. The commonest indication for liver resection was metastatic colorectal cancer (n=1). The median operating time was 142.5 minutes and 67% of patients (n=10) had portal clamping for a median of 21.5 minutes. The median length of hospitalization was 12 days with an ICU stay of 1 day, 27% (n=4) had major surgical complications. A further 20% (n=3) had exacerbations of pre-existing comorbities. Conclusion. Liver resection can be performed safely in octogenarians within a tertiary referral unit. It has a low mortality and an acceptable level of morbidity in carefully selected octogenarians