Structure and energetics of solvated ferrous and ferric ions: Car-Parrinello molecular dynamics in the DFT+U formalism

We implemented a rotationally-invariant Hubbard U extension to density-functional theory in the Car-Parrinello molecular dynamics framework, with the goal of bringing the accuracy of the DFT+U approach to finite-temperature simulations, especially for liquids or solids containing transition-metal ions. First, we studied the effects on the Hubbard U on the static equilibrium structure of the hexa-aqua ferrous and ferric ions, and the inner-sphere reorganization energy for the electron-transfer reaction between aqueous ferrous and ferric ions. It is found that the reorganization energy is increased, mostly as a result of the Fe-O distance elongation in the hexa-aqua ferrous ion. Second, we performed a first-principles molecular dynamics study of the solvation structure of the two aqueous ferrous and ferric ions. The Hubbard term is found to change the Fe-O radial distribution function for the ferrous ion, while having a negligible effect on the aqueous ferric ion. Moreover, the frequencies of vibrations between Fe and oxygen atoms in the first-solvation shell are shown to be unaffected by the Hubbard corrections for both ferrous and ferric ions.Comment: 13 pages, 2 figures, 1 table. Submitted to Journal of Electroanalytical Chemistr

Dog Ownership and Dog Walking: The Relationship with Exercise, Depression and Hopelessness in Patients with Ischemic Heart Disease

Background: Dog ownership has been associated with increased physical activity in the general adult population. Objective: The objective of this study was to examine dog ownership and dog walking and their relationship with home-based and Phase II cardiac rehabilitation exercise, depression, and hopelessness in patients with ischemic heart disease (IHD). Methods: A total of 122 IHD patients were included in this prospective observational study. Patients completed dog ownership/walking questions during their hospitalization. The Cardiac Rehabilitation Exercise Participation Tool, Patient Health Questionaire-9 (PHQ-9), and State-Trait Hopelessness Scale were completed by mail at 3, 8, or 12 months later. Regression modeling was used to evaluate the significance of dog ownership/walking on exercise, depression and hopelessness. Results: The sample was 34.4% female and had a mean age of 64.7±9.1 years. Forty-two patients (34.4%) reported owning a dog. Patients who owned, but did not walk their dog, reported significantly lower levels of home exercise compared to patients who walked their dogs at least 1 day/week (non-dog walkers: 36.8% vs. dog walkers: 73.9%, p=0.019). The odds of participating in home exercise were significantly higher for dog walkers compared to non-dog walkers (OR 8.1 [1.7, 38.5] vs. 1.0). There were no differences in Phase II cardiac rehabilitation exercise, depression or hopelessness between dog owners and non-dog owners or between dog walkers and non-dog walkers. Conclusions: These findings show a beneficial effect on home-based exercise for those who dog-walk at least 1 day/week. Health care professionals should encourage dog walking to increase dog owners’ physical activity levels

Children's Use of Electronic Games: Choices of Game Mode and Challenge Levels

Introduction. Interactive electronic games are popular and are believed to contribute to physical activity accrual. The purpose of this study was to examine children's electronic game use during conditions in which they had free access to selecting interactive and seated screen-based versions of electronic games and during the interactive versions had free choice in making adjustments to the activity intensity. Methods. We systematically observed 60 Hong Kong primary school children during two 60-minute game sessions while simultaneously recording their game mode choices and physical activity levels using SOFIT (System for Observing Fitness Instruction Time). Results. When given free choice, children spent more than half of their available time participating in interactive versions of games. These versions of games provided significantly more moderate-to-vigorous physical activity and greater energy expenditure than the computer screen versions. Children with the opportunity to modify intensity levels spent more time playing the interactive versions and accrued more physical activity. Conclusions. The tenets of behavioral choice theory were supported. Access to new-generation interactive games, particularly those with modifiable intensity levels, may facilitate children's participation in physical activity

Assessment of measures of physical activity of children with cerebral palsy at home and school: a pilot study

ABSTRACTHome and school are important settings where children can accrue health promoting physical activity (PA). Little&nbsp;is known about the PA levels and associated environmental characteristics at home and school in children with&nbsp;cerebral palsy (CP). An observational tool - Behaviors of Eating and Activity for Children&rsquo;s Health Evaluation System&nbsp;(BEACHES) - offers potential for providing information.Objective: To validate BEACHES against Actigraph accelerometer and to document PA of children with CP at&nbsp;a special residential school facility for children with physical disabilities.Methods: Five children with CP (2 girls, 3 boys; aged 9.82 &plusmn; 2.39 years) in Level I of the Gross Motor Function&nbsp;Classification System (GMFCS) participated. PA monitoring was conducted once a week during four consecutive&nbsp;weeks at morning recess at school and during after school hours at the children&rsquo;s residence. Estimates of time&nbsp;spent being sedentary and being active were derived from the Actigraph and compared to estimates obtained with&nbsp;BEACHES.Results: Children&rsquo;s PA observed using BEACHES was comparable to the Actigraph estimations. In general,&nbsp;children were more active at recess than after school and the physical locations assessed by BEACHES were&nbsp;associated with objectively measured PA time.Conclusion: This pilot study indicates that BEACHES appears to be a suitable measure of PA for children with&nbsp;CP in both home and school settings. Additional study with a larger and more diverse sample is recommended to&nbsp;verify the results.</div

Hydrogen bonding and coordination in normal and supercritical water from X-ray inelastic scattering

A direct measure of hydrogen bonding in water under conditions ranging from the normal state to the supercritical regime is derived from the Compton scattering of inelastically-scattered X-rays. First, we show that a measure of the number of electrons $n_e$ involved in hydrogen bonding at varying thermodynamic conditions can be directly obtained from Compton profile differences. Then, we use first-principles simulations to provide a connection between $n_e$ and the number of hydrogen bonds $n_{HB}$. Our study shows that over the broad range studied the relationship between $n_e$ and $n_{HB}$ is linear, allowing for a direct experimental measure of bonding and coordination in water. In particular, the transition to supercritical state is characterized by a sharp increase in the number of water monomers, but also displays a significant number of residual dimers and trimers.Comment: 14 pages, 5 figures, 1 tabl

Income inequalities under economic restructuring in Hong kong

Hong Kong's income inequalities have long been situated at a relatively high level by international standards. This paper investigates the factors that have contributed to this prolonged phenomenon. We argue that in the absence of appropriate government actions, economic progress in a laissez-faire capitalist system cannot necessarily equalize income distribution. © 2004 by The Regents of the University of California.link_to_subscribed_fulltex

Red clover necrotic mosaic virus replication proteins accumulate at the endoplasmic reticulum

AbstractRed clover necrotic mosaic virus (RCNMV) encodes N-terminally overlapping proteins of 27 and 88 kDa (p27 and p88) known to be required for replication. Green fluorescent protein (GFP) fusions were used to visualize the location of p27 and p88 within Nicotiana benthamiana cells. GFP:p27 fusions localized to the endoplasmic reticulum (ER), co-localized with ER-targeted yellow fluorescent protein and caused membrane restructuring and proliferation. Cellular fractionation of virus-inoculated N. benthamiana leaves confirmed the association of p27 with ER membranes. GFP:p88 fusions also localized to the ER and co-localized with GFP:p27. Both fusion proteins co-localize to the cortical and cytoplasmic ER and were associated with invaginations of the nuclear envelope. Independent accumulation in, and perturbation of, the ER suggests that p27 and p88 function together in the replication complex. This is the first report of a member of the Tombusviridae replicating in association with the ER

GEAR: A GPU-Centric Experience Replay System for Large Reinforcement Learning Models

This paper introduces a distributed, GPU-centric experience replay system, GEAR, designed to perform scalable reinforcement learning (RL) with large sequence models (such as transformers). With such models, existing systems such as Reverb face considerable bottlenecks in memory, computation, and communication. GEAR, however, optimizes memory efficiency by enabling the memory resources on GPU servers (including host memory and device memory) to manage trajectory data. Furthermore, it facilitates decentralized GPU devices to expedite various trajectory selection strategies, circumventing computational bottlenecks. GEAR is equipped with GPU kernels capable of collecting trajectories using zero-copy access to host memory, along with remote-directed-memory access over InfiniBand, improving communication efficiency. Cluster experiments have shown that GEAR can achieve performance levels up to 6× greater than Reverb when training state-of-the-art large RL models. GEAR is open-sourced at https://github.com/bigrl-team/gear