Microglia-passaged simian immunodeficiency virus induces neurophysiological abnormalities in monkeys

Four rhesus macaques were inoculated intravenously with a cryopreserved stock of microglia obtained from a simian immunodeficiency virus (SIV)-infected rhesus macaque. Before infection, three of the four monkeys were trained and tested daily on a computerized neuropsychological test battery. After SIV infection, behavioral testing continued to monitor deficits associated with disease progression. Five additional age-matched, behaviorally trained monkeys served as controls. Neurophysiological testing for visual and auditory evoked responses was accomplished 37-52 weeks after infection in all monkeys. Subsequently, all four SIV-infected monkeys and one control subject were sacrificed, and samples of brain tissue were taken for pathological analysis. SIV-infected monkeys demonstrated abnormal responses in both auditory and visual evoked responses. In addition, around the time of electrophysiological recording, all three SIV-infected, behaviorally trained monkeys exhibited significant decreases in progressive-ratio performance, reflecting a reduction in reinforcer efficacy. One subject also demonstrated impairments in shifting of attentional set and motor ability at that time. Neuropathological evaluation revealed that all four SIV-infected monkeys exhibited numerous perivascular and parenchymal infiltrating T cells. These findings document that SIV causes electrophysiological, behavioral, and neuropathological sequelae similar to what has been observed in the human neuroAIDS syndrome. Our observations further validate the simian model for the investigation of the pathogenesis of AIDS dementia and for the investigation of drugs with potential therapeutic benefits.     

Characterization of the rat myometrial contractile response to neuropeptide Y

The in vitro contractile effect of neuropeptide Y (NPY) on rat myometrial strips was for the first time demonstrated and characterised, and the EC50 value estimated to be 267 +/- 87 nM. This effect is presumably mediated by the NPY1 receptor being responsible for postsynaptic effects throughout the peripherial nervous system, thus indicating a direct uterotonic effect of NPY. Further, the effect was demonstrated to the dependent on extracellular Ca2+. Short-term exposures to NPY markedly desensitized the tissue affecting subsequent responses to NPY as well as to oxytocin (OT). This desensitization was time and concentration-dependent, but lasted less than three hours. However, long-term infusions of NPY for 5 days increased to response to both NPY and OT. Long-term infusions of OT caused a marked decrease of the NPY response, and it is concluded that common pathways for up and down regulation of the myometrial responsiveness to several peptide hormones may exist.     

An analysis of alternatives for computing axisymmetric element stiffness matrices

This note compares the use of numerical and closed form integration in computation of element stiffness matrices for axisymmetric finite element analysis. Only constant strain elements are considered. Results obtained with Gaussian quadrature and closed form integrators are compared mutually and with an exact solution obtained from classical methods. The FEM global equations estimate the force-displacement behaviour of an elastic continuum with an accuracy that depends on the integration method used. Selection of an integration order minimizing error is particularly critical in the presence of high stress gradients. Best results in the vicinity of the axis of revolution may be obtained with single-point integration rather than higher order approximations or exact integration of the element stiffness matrix. This phenomenon and its consequences are subsequently discussed.     

Bayesian system identification via Markov chain Monte Carlo techniques

The work here explores new numerical methods for supporting a Bayesian approach to parameter estimation of dynamic systems. This is primarily motivated by the goal of providing accurate quantification of estimation error that is valid for arbitrary, and hence even very short length data records. The main innovation is the employment of the Metropolis-Hastings algorithm to construct an ergodic Markov chain with invariant density equal to the required posterior density. Monte Carlo analysis of samples from this chain then provides a means for efficiently and accurately computing posteriors for model parameters and arbitrary functions of them.     

Bounds Checking on GPU

International Journal of Parallel Programming - We present a simple compilation strategy for safety-checking array indexing in high-level languages on GPUs. Our technique does not depend on...     

Short-term responses in production and behavior during periods of change in concentrate allowance for dairy cows

The aim of this study was to investigate the short-term responses of dairy cows during periods of change in the concentrate allowance in an automatic milking system. The experiment had a design with a 2 × 2 factorial arrangement including 2 types of concentrates and 2 amounts of concentrates (type O: mix of pelleted concentrate and steamrolled, acidified barley; type S: pelleted) in amounts of 3 and 6 kg/d. The experiment length was 11 wk. The concentrate type changed between wk 6 and 7 and included both increase and decrease in concentrate allowance for each concentrate type. The concentrate allowance was changed by 0.5 kg/d over 6 d. The 96 cows (48 Danish Jersey, 48 Danish Holstein) included in the experiment were blocked according to breed, parity, and days in milk, and randomly divided into 8 groups of treatment order. The cows visited the automatic milking unit more often when concentrate type O was offered, but not when an increased concentrate allowance was provided. The changes in concentrate intake and partial mixed ration (PMR) eating time showed a symmetrical pattern between the periods of increasing allowance and decreasing allowance. However, PMR intake and milk yield varied in the magnitude of the responses, indicating that these responses may not be driven by the same underlying mechanisms during increase and decrease in concentrate allowance. The daily lying time increased and the PMR eating rate decreased during periods of both increase and decrease in concentrate allowance. We found no significant change in milk yield during increase in concentrate allowance, despite a higher milk yield during periods with constant concentrate allowance at the high concentrate amount; however, the milk yield decreased during periods of decrease in concentrate allowance. Visit frequency, lying time, and steps changed during periods of changes in concentrate allowance without showing any differences at the constant concentrate allowance. In conclusion, these results indicate that it may be difficult to adjust the individual concentrate allowance based on the short-term responses of the cow.     

Digital assessment in higher education

Statistics show there is a clear relationship between higher education and employment in Norway, especially for people with disabilities. The use of digital assessment solutions is increasing in Norwegian higher education. The overall goal of this study is therefore to highlight the potential for improvement of current practices related to universal design, both for providers of digital assessment solutions and for higher education institutions. Based on a case study of practices in Norwegian higher education sector, this article reviews existing requirements for ensuring universal design in digital assessment solutions, prototypes an approach to evaluating universal design quality (UD-Q) of two major Norwegian digital assessment solutions and investigates the compliance between providers’ self-assessments from interviews and UD-Q evaluation scores. The article presents two contributions: (1) an improved set of requirements for universal usability when procuring digital assessments solutions and (2) UD-Q, a stepwise feature analysis-based expert inspection method for evaluating the UD-Q of digital assessment solutions.     

Push-pull tests to quantify in situ degradation rates at a phytoremediation site

Nine push-pull tests (PPTs) were performed to determine in-situ aerobic respiration rates at a creosote-contaminated site and to assess the contribution of hybrid poplar trees to the remediation of polynuclear aromatic hydrocarbons (PAH) in groundwater. PPTs were conducted by injecting a solution containing dissolved oxygen and naphthalene (reactive tracers) with bromide (nonreactive tracer) into wells constructed in a shallow unconfined aquifer. The objective of this study was to determine seasonal variation and spatial differences (contaminated versus uncontaminated areas and treed versus untreed areas) in the rate of consumption of dissolved oxygen. First-order aerobic respiration rates varied from 0.0 (control well) to 1.25 hr(-1), which occurred at a planted area in early summer (June). Rates measured in winter at treed areas were greater by a factor of 3-5 when compared to winter rates determined at nontreed areas of the site. Rates at treed regions were found to increase by over 4 times in summer relative to winter at the same location.