The influence of dual-task conditions on movement in young adults with and without Down syndrome

This investigation compared spatial and temporal movement parameters of a sample of young adults with Down syndrome (DS) (N = 12) and individuals without disabilities (IWD) (N = 12) under dual-task conditions. Subjects performed a walking task at a preferred speed in isolation and again while holding a plate and cup, carrying tray and cups, talking on a phone, or buttoning a shirt. Spatial and temporal values were compared using a 2 (group) × 5 (conditions) repeated measures analysis of variance. Analysis of spatial components separately indicated that step length, step width, stride length and stride width revealed significant group and condition interactions (p ≤ .01). Temporal components yielded significance in velocity and single-leg support time (p ≤ .01). The current results support the notion that along with impairments to qualitative motor skills, individuals with DS are also impaired in higher order executive functioning (EF), as measured by a dual-task paradigm. It was concluded that movements are less efficient and functional in individuals with DS when an additional task is encountered while walking. We theorized that the motor program was sufficient for general locomotion but was not sufficiently developed to allow individuals with DS to modify or alter their movements to changing cognitive conditions that increasingly taxed EF. As gait and balance are trainable in this population, we recommend developing appropriate exercise and motor skill interventions during childhood and adolescents to increase strength, stability, and more “robust” ambulatory motor schema.     

Influence of delayed CSF storage on concentrations of phospho-tau protein (181), total tau protein and beta-amyloid (1-42)

It is generally accepted that cerebrospinal fluid (CSF) biomarkers such as tau protein, phosphorylated tau protein (threonine 181) and beta-amyloid (1-42) can facilitate early and differential diagnosis of Alzheimer's disease (AD). Since the respective concentrations can only be measured in a number of specialized centers, time to CSF specimen work-up has been considered as crucial for the stability of the respective biomarkers. When shipping of CSF samples is needed for biomarker measurement and immediate freezing of samples is not available, an overnight delay of up to 24h frequently occurs. Therefore, we investigated the potential impact of a 24h delayed freezing on CSF biomarker concentrations and compared it to 2h storage (room temperature, 20 degrees C) and an immediate freezing. First, storage at room temperature for 2h had only marginal, non-significant effects on the concentrations of CSF total tau protein and phospho-tau protein (181) compared to immediate freezing. Second, storage at room temperature for 24h did not significantly affect total tau protein or phospho-tau protein but beta-amyloid (1-42) concentrations which increased significantly compared to the samples frozen immediately. These results indicate that CSF samples for the evaluation of total tau and phospho-tau protein may be kept at room temperature for up to 24h whereas CSF samples for beta-amyloid (1-42) need to be frozen immediately.     

Fine-tuning of social play in juvenile lowland gorillas (gorilla gorilla gorilla)

Social play, which involves cooperation, communication, and learning, may represent a suitable field for the investigation of cognitive ability in a given species. We collected data on a captive group of gorillas in order to evaluate the potential cognitive skill of juveniles in fine-tuning play behavior. This study revealed that juvenile gorillas are able to "place" the play session in a proper spatial/temporal context, thus evaluating a complex net of factors (e.g., play partner, play roughness, group activity, space availability). When animals play fight, they use patterns of agonistic functional contexts. Since these actions are not intrinsically different from their "serious" context, it may be hard to distinguish them. One of the most important function of play in the ontogeny of primate social cognition may be to recognize stimuli, which may indicate the intentions of conspecifics. Accordingly, we found that juvenile gorillas are able to use play signals appropriately when a clear statement of purpose is necessary (i.e., during male-male competitive play sessions and when the escape opportunities are limited). The ability to interpret such ambiguous features of social signaling could represent a central issue in the evolution of behavioral flexibility and intelligence in primates.     

The relevance of psychosocial variables and working conditions in predicting nurses' coping strategies during the SARS crisis: an online questionnaire survey

OBJECTIVES: The purpose of this investigation was to examine the relationship between psychosocial variables and working conditions, and nurses' coping methods and distress in response to the severe acute respiratory syndrome (SARS) crisis in Canada. PARTICIPANTS AND PROCEDURE: The sample consisted of 333 nurses (315 women, 18 men) who completed an Internet-mediated questionnaire that was posted on the Registered Nurses' Association of Ontario (RNAO) website between March and May 2004. The questionnaire was restricted to respondents who had to authenticate their RNAO membership with a valid username and password before accessing the questionnaire. This served a dual purpose: to ensure that only RNAO nurses completed the questionnaire and thereby safeguarding the generalizability of the findings; and second, to prevent any one nurse from contributing more than once to the overall sample. RESULTS: Correlational analysis yielded several significant relationships between psychosocial variables and working conditions, and the traditional correlates of burnout and stress. Three multiple regression analysis revealed that the model we evolved--including higher levels of vigor, organizational support, and trust in equipment/infection control initiative; and lower levels of contact with SARS patients, and time spent in quarantine--predicted to lower levels of avoidance behavior, emotional exhaustion, and state anger. CONCLUSIONS: By employing models of stress and burnout that combine psychosocial variables and working conditions, researchers can account for significant amounts of variance in outcomes related to burnout. These findings highlight the importance of vigor and perceived organizational support in predicting nurses' symptoms of burnout. For healthcare administrators, this means that a likely strategy for assuaging the negative outcomes of stress should address nurses' psychosocial concerns and the working conditions that they face during novel times of crisis.     

Influence of Test Conditions on Sliding Wear Performance of High Velocity Air Fuel-Sprayed WC–CoCr Coatings

Sliding wear performance of thermal spray WC-based coatings has been widely studied. However, there is no systematic investigation on the influence of test conditions on wear behaviour of these coatings. In order to have a good understanding of the effect of test parameters on sliding wear test performance of HVAF-sprayed WC–CoCr coatings, ball-on-disc tests were conducted under varying test conditions, including different angular velocities, loads and sliding distances. Under normal load of 20 N and sliding distance of 5 km (used as ‘reference’ conditions), it was shown that, despite changes in angular velocity (from 1333 rpm up to 2400 rpm), specific wear rate values experienced no major variation. No major change was observed in specific wear rate values even upon increasing the load from 20 N to 40 N and sliding distance from 5 km to 10 km, and no significant change was noted in the prevailing wear mechanism, either. Results suggest that no dramatic changes in applicable wear regime occur over the window of test parameters investigated. Consequently, the findings of this study inspire confidence in utilizing test conditions within the above range to rank different WC-based coatings.     

Influence of Boundary Conditions on Numerical Homogenization of High Performance Concrete

Concrete is the most widely used construction material nowadays. We are concerned with the computational modelling and laboratory testing of high-performance concrete (HPC). The idea of HPC is to enhance the functionality and sustainability of normal concrete, especially by its greater ductility as well as higher compressive, tensile, and flexural strengths. In this paper, the influence of three types (linear displacement, uniform traction, and periodic) of boundary conditions used in numerical homogenization on the calculated values of HPC properties is determined and compared with experimental data. We take into account the softening behavior of HPC due to the development of damage (micro-cracks), which finally leads to failure. The results of numerical simulations of the HPC samples were obtained by using the Abaqus package that we supplemented with our in-house finite element method (FEM) computer programs written in Python and the homogenization toolbox Homtools. This has allowed us to better account for the nonlinear response of concrete. In studying the microstructure of HPC, we considered a two-dimensional representative volume element using the finite element method. Because of the random character of the arrangement of concrete’s components, we utilized a stochastic method to generate the representative volume element (RVE) structure. Different constitutive models were used for the components of HPC: quartz sand—linear elastic, steel fibers—ideal elastic-plastic, and cement matrix—concrete damage plasticity. The numerical results obtained are compared with our own experimental data and those from the literature, and a good agreement can be observed.