58 research outputs found
Benchmarking the performance of density functional theory and point charge force fields in their description of sI methane hydrate against diffusion Monte Carlo.
No full textHigh quality reference data from diffusion Monte Carlo calculations are presented for bulk sI methane hydrate, a complex crystal exhibiting both hydrogen-bond and dispersion dominated interactions. The performance of some commonly used exchange-correlation functionals and all-atom point charge force fields is evaluated. Our results show that none of the exchange-correlation functionals tested are sufficient to describe both the energetics and the structure of methane hydrate accurately, while the point charge force fields perform badly in their description of the cohesive energy but fair well for the dissociation energetics. By comparing to ice [Formula: see text], we show that a good prediction of the volume and cohesive energies for the hydrate relies primarily on an accurate description of the hydrogen bonded water framework, but that to correctly predict stability of the hydrate with respect to dissociation to ice [Formula: see text] and methane gas, accuracy in the water-methane interaction is also required. Our results highlight the difficulty that density functional theory faces in describing both the hydrogen bonded water framework and the dispersion bound methane
Molecular brakes regulating mTORC1 activation in skeletal muscle following synergist ablation
No full textThe goal of the current work was to profile positive (mTORC1 activation, autocrine/paracrine growth factors) and negative [AMPK, unfolded protein response (UPR)] pathways that might regulate overload-induced mTORC1 activation with the hypothesis that a number of negative regulators of mTORC1 will be engaged during a supra-physiological model of hypertrophy. To achieve this, mTORC1-IRS1/2 signaling, BiP/CHOP/IRE1a, and AMPK activation were determined in rat plantaris muscle following synergist ablation (SA). SA resulted in significant increases in muscle mass of ~4% per day throughout the 21 days of the experiment. The expression of the insulin-like growth factors were high throughout the 21d of overload. However, IGF signaling was limited since IRS1 and 2 were undetectable in the overloaded muscle from day 3 to day 9. The decreases in IRS1/2 protein were paralleled by increases in GRB10(Ser501/503) and S6K1(Thr389) phosphorylation, two mTORC1 targets that can destabilize IRS proteins. PKB(Ser473) phosphorylation was higher from 3-6 days and this was associated with increased TSC2(Thr939) phosphorylation. The phosphorylation of TSC2(Thr1345) (an AMPK site) was also elevated whereas phosphorylation at the other PKB site, Thr(1462), was unchanged at 6d. In agreement with the phosphorylation of Thr(1345), synergist ablation led to activation of a1-AMPK during the initial growth phase, lasting the first 9 days before returning to baseline by day 12. The UPR markers CHOP and BiP were elevated over the first 12 days following ablation, whereas IRE1a levels decreased. These data suggest that during supra-physiological muscle loading, at least three potential molecular brakes engage to down-regulate mTORC1
Quantum Monte Carlo, Or, Solving the Many-Particle Schrödinger Equation Accurately While Retaining Favorable Scaling with System Size
No full textValidation of Facial Attributions in Leadership:Trustworthiness and Age in Chinese Mid-Level Management
No full textThe attributions made to faces are well described by two dimensions of apparent trustworthiness (valence or warmth) and apparent competence (dominance and power) (Todorov A, Mende-Siedlecki P, Dotsch R. Curr Opin Neurobiol, 2013, 23, 373–80). This model has been extended to include a third dimension of apparent age and attractiveness (Sutherland CAM, Oldmeadow JA, Santos IM, Towler J, Michael Burt D, Young AW. Cognition, 2013, 127, 105–18). Previous research has tested the association between appearance and leadership attainment for high-level leaders such as elite politicians and chief executive officers of top performing organisations in the US and Western Europe. Here we focus on a Chinese organisational context and explore how facial attributions are associated with appointment at mid-level managerial positions. Participants rated leadership, competence, trustworthiness, attractiveness and age of faces of male employees of a Chinese Real Estate company. Our findings reveal that apparent trustworthiness and age are more critical predictors of leadership attainment than competence or attractiveness in the context of mid-level management in China. The study supports the three-dimensional attribution framework and reaffirms the importance of facial cues in leadership selection across diverse cultural settings.</p
An examination of college student wellness: A research and liberal arts perspective
No full textPromoting wellness within academia reduces disease frequency and enhances overall health. This study examined wellness factors among undergraduate students attending a research university ( n = 85) or a small liberal arts college ( n = 126). Participants were administered surveys which measured physical, emotional, social, intellectual , and occupational wellness. Significant institutional differences emerged on measures of physical and social wellness. When collapsed across academic institutions, students who were gainfully employed reported greater self-efficacy compared with unemployed students. Gender differences emerged on measures of physical and social well-being. Our findings support the need for targeted interventions that facilitate enhanced college student development and well-being
Benchmark all-electron ab initio quantum Monte Carlo calculations for small molecules
No full textWe study the efficiency, precision and accuracy of all-electron variational and diffusion quantum Monte Carlo calculations using Slater basis sets. Starting from wave functions generated by Hartree-Fock and density functional theory, we describe an algorithm to enforce the electron-nucleus cusp condition by linear projection. For the 55 molecules in the G2 set, the diffusion quantum Monte Carlo calculations recovers an average of 95% of the correlation energy and reproduces bond energies to a mean absolute deviation of 3.2 kcal/mol. Comparing the individual total energies with essentially exact values, we investigate the error cancellation in atomization and chemical reaction path energies, giving additional insight into the sizes of nodal surface errors
Blunting of AICAR-induced human skeletal muscle glucose uptake in type 2 diabetes is dependent on age rather than diabetic status
No full textBabraj JA, Mustard K, Sutherland C, Towler MC, Chen S, Smith K, Green K, Leese GP, Hardie DG, Rennie MJ, Cuthbertson DJ. Blunting of AICAR-induced human skeletal muscle glucose uptake in type 2 diabetes is dependent on age rather than diabetic status. Am J Physiol Endocrinol Metab 296: E1042-E1048, 2009. First published February 3, 2009; doi: 10.1152/ajpendo.90811.2008.-We demonstrated previously that, in healthy young men, 5-aminoimidazole-4-carboxamide 1-beta-D-ribofuranoside (AICAR) stimulates human muscle 2-deoxyglucose (2DG) uptake without detectable activation of muscle AMP-activated protein kinase (AMPK) but with extracellular-regulated kinase 1/2 (ERK1/2) activation. We tested whether AICAR stimulates muscle 2DG uptake in healthy older patients with or without type 2 diabetes (T2D). Six healthy young subjects (23 +/- 3 yr, BMI 25 +/- 2 kg/m(-2); means +/- SE), eight older subjects (59 +/- 4 yr, BMI 28 +/- 2 kg/m(-2)), and eight subjects with T2D (62 +/- 4 yr, BMI 27 +/- 2 kg/m(-2)) received a 6-h 2DG infusion (prime 10 mg/kg, 6 mg.kg(-1).h(-1)) and AICAR (10 or 20 mg.kg(-1).h(-1)) from 3 to 6 h. Quadriceps biopsies were taken at 0, 3, and 6 h. We determined 1) 2DG uptake, 2) total AMPK alpha activity, AMPK, acetyl-CoA carboxylase (ACC), and AS160 phosphorylation, and 3) ERK1/2 phosphorylation. Ten milligrams per kilogram per hour AICAR increased 2DG uptake by 2.9 +/- 0.7-fold in young men (P < 0.001), 1.8 +/- 0.2-fold in older men (P < 0.01), and 1.6 +/- 0.1-fold in men with T2D; 20 mg.kg(-1).h(-1) AICAR increases were 2.5 +/- 0.1-fold (older men, P < 0.001) and 2.2 +/- 0.2-fold (men with T2D, P < 0.001). At 3-h AMPK activity and AMPK, ACC and AS160 phosphorylation were unchanged, but ERK1/2 phosphorylation increased at both AICAR doses. The fold changes of ERK1/2 phosphorylation and 2DG uptake closely correlated (R-2 = 0.55, P = 0.003). AICAR stimulates muscle 2DG uptake in T2D to the same extent as in healthy age-matched controls, but there is an age-related reduction.</p
Adaptation improves face trustworthiness discrimination
No full textAdaptation to facial characteristics, such as gender and viewpoint, has been shown to both bias our perception of faces and improve facial discrimination. In this study, we examined whether adapting to two levels of face trustworthiness improved sensitivity around the adapted level. Facial trustworthiness was manipulated by morphing between trustworthy and untrustworthy prototypes, each generated by morphing eight trustworthy and eight untrustworthy faces, respectively. In the first experiment, just-noticeable differences (JNDs) were calculated for an untrustworthy face after participants adapted to an untrustworthy face, a trustworthy face, or did not adapt. In the second experiment, the three conditions were identical, except that JNDs were calculated for a trustworthy face. In the third experiment we examined whether adapting to an untrustworthy male face improved discrimination to an untrustworthy female face. In all experiments, participants completed a two-interval forced-choice (2-IFC) adaptive staircase procedure, in which they judged which face was more untrustworthy. JNDs were derived from a psychometric function fitted to the data. Adaptation improved sensitivity to faces conveying the same level of trustworthiness when compared to no adaptation. When adapting to and discriminating around a different level of face trustworthiness there was no improvement in sensitivity and JNDs were equivalent to those in the no adaptation condition. The improvement in sensitivity was found to occur even when adapting to a face with different gender and identity. These results suggest that adaptation to facial trustworthiness can selectively enhance mechanisms underlying the coding of facial trustworthiness to improve perceptual sensitivity. These findings have implications for the role of our visual experience in the decisions we make about the trustworthiness of other individuals
- …
