Data Compression System with a Minimum Time Delay Unit-Patent

Minimum time delay unit for conventional time multiplexed data compression channel

Laboratory modeling and analysis of aircraft-lightning interactions

Modeling studies of the interaction of a delta wing aircraft with direct lightning strikes were carried out using an approximate scale model of an F-106B. The model, which is three feet in length, is subjected to direct injection of fast current pulses supplied by wires, which simulate the lightning channel and are attached at various locations on the model. Measurements are made of the resulting transient electromagnetic fields using time derivative sensors. The sensor outputs are sampled and digitized by computer. The noise level is reduced by averaging the sensor output from ten input pulses at each sample time. Computer analysis of the measured fields includes Fourier transformation and the computation of transfer functions for the model. Prony analysis is also used to determine the natural frequencies of the model. Comparisons of model natural frequencies extracted by Prony analysis with those for in flight direct strike data usually show lower damping in the in flight case. This is indicative of either a lightning channel with a higher impedance than the wires on the model, only one attachment point, or short streamers instead of a long channel

Accelerating COBAYA3 on multi-core CPU and GPU systems using PARALUTION

COBAYA3 is a multi-physics system of codes which includes two 3D multi-group neutron diffusion codes, ANDES and COBAYA3-PBP, coupled with COBRA-TF, COBRA-IIIc and SUBCHANFLOW sub-channel thermal-hydraulic codes, for the simulation of LWR core transients. The 3D multi-group neutron diffusion equations are expressed in terms of a sparse linear system which can be solved using different iterative Krylov subspace solvers. The mathematical SPARSKIT library has been used for these purposes as it implements among others, external GMRES, PGMRES and BiCGStab solvers. Multi-core CPUs and graphical processing units (GPUs) provide high performance capabilities which are able to accelerate many scientific computations. To take advantage of these new hardware features in daily use computer codes, the integration of the PARALUTION library to solve sparse systems of linear equations is a good choice. It features several types of iterative solvers and preconditioners which can run on both multi-core CPUs and GPU devices without any modification from the interface point of view. This feature is due to the great portability obtained by the modular and flexible design of the library. By exploring this technology, namely the implementation of the PARALUTION library in COBAYA3, we are able to decrease the solution time of the sparse linear systems by a factor 5.15x on GPU and 2.56x on multi-core CPU using standard hardware. These obtained speedup factors in addition to the implementation details are discussed in this paper

Correlates of sedentary behaviours in preschool children: a review

Background: Sedentary behaviour has been linked with a number of health outcomes. Preschool-aged children spend significant proportions of their day engaged in sedentary behaviours. Research into the correlates of sedentary behaviours in the preschool population is an emerging field, with most research being published since 2002. Reviews on correlates of sedentary behaviours which include preschool children have previously been published; however, none have reported results specific to the preschool population. This paper reviews articles reporting on correlates of sedentary behaviour in preschool children published between 1993 and 2009.Methods: A literature search was undertaken to identify articles which examined correlates of sedentary behaviours in preschool children. Articles were retrieved and evaluated in 2008 and 2009.Results: Twenty-nine studies were identified which met the inclusion criteria. From those studies, 63 potential correlates were identified. Television viewing was the most commonly examined sedentary behaviour. Findings from the review suggest that child&rsquo;s sex was not associated with television viewing and had an indeterminate association with sedentary behaviour as measured by accelerometry. Age, body mass index, parental education and race had an indeterminate association with television viewing, and outdoor playtime had no association with television viewing. The remaining 57 potential correlates had been investigated too infrequently to be able to draw robust conclusions about associations.Conclusions: The correlates of preschool children&rsquo;s sedentary behaviours are multi-dimensional and not well established. Further research is required to provide a more comprehensive understanding of the influences on preschool children&rsquo;s sedentary behaviours to better inform the development of interventions.<br /

Biochemical characterization of glutaredoxins from Chlamydomonas reinhardtii reveals the unique properties of a chloroplastic CGFS-type glutaredoxin.

Glutaredoxins (GRXs) are small ubiquitous disulfide oxidoreductases known to use GSH as electron donor. In photosynthetic organisms, little is known about the biochemical properties of GRXs despite the existence of approximately 30 different isoforms in higher plants. We report here the biochemical characterization of Chlamydomonas GRX1 and GRX3, the major cytosolic and chloroplastic isoforms, respectively. Glutaredoxins are classified on the basis of the amino acid sequence of the active site. GRX1 is a typical CPYC-type GRX, which is reduced by GSH and exhibits disulfide reductase, dehydroascorbate reductase, and deglutathionylation activities. In contrast, GRX3 exhibits unique properties. This chloroplastic CGFS-type GRX is not reduced by GSH and has an atypically low redox potential (-323 +/- 4 mV at pH 7.9). Remarkably, GRX3 can be reduced in the light by photoreduced ferredoxin and ferredoxin-thioredoxin reductase. Both GRXs proved to be very efficient catalysts of A(4)-glyceraldehyde-3-phosphate dehydrogenase deglutathionylation, whereas cytosolic and chloroplastic thioredoxins were inefficient. Glutathionylated A(4)-glyceraldehyde-3-phosphate dehydrogenase is the first physiological substrate identified for a CGFS-type GRX

Older female children experience poorer quality of life when levels of perceived racial bias are high

Background: Individuals with sickle cell disease (SCD) experience significant health problems that result in unpredictable pain episodes and frequent healthcare utilization. Disparities in clinical care and emergency room visits in which medical providers mistrust the severity of reported pain symptoms may contribute to health-related stigma. In addition to stigma related to seeking care for acute pain, racism is a source of stigma with associated systemic inequities for this majority Black population. There is currently limited research into the effects of health-related stigma and racial bias on the underserved SCD population; however, the small body of research has found barriers to healthcare utilization, greater pain burden, and increased emotional distress. There is little known about the influence of health-related stigma and racial bias on quality of life (QOL) of children with SCD. The present study assessed these relationships, and additionally, we sought to understand whether there were differences in this relationship with regards to demographic factors (e.g., age, gender). / Methods: Data was collected from African-American children with SCD aged 8 - 16 years (57% male, 63% HbSS) who received care at a medical center in the United States. Sixty-three percent of children were receiving chronic transfusion therapy or pheresis and 37% were receiving hydroxyurea therapy. Children completed the Childhood Stigma Scale (adapted for SCD), the Child Perceptions of Racism in Children and Youth scale (PRaCY), and the Pediatric Quality of Life Inventory for SCD (PedsQL). Caregivers provided demographic information. / Results: We first assessed whether age, gender, and health-related stigma predicted QOL and demonstrated a significant overall model, F(7, 22) = 4.59, p = .003, r = .46. Health-related stigma (p = .007) predicted QOL, but neither age or gender were significant predictors. The next model assessed whether age, gender, and racial bias predicted QOL and demonstrated a significant overall model, F(7, 22) = 4.59, p < .001, r = .52. Specifically, age (p = .03), but neither gender or racial bias were significant predictors. Of interest, there was a significant interaction between age, gender, and racial bias (p = .02), which indicated that males generally had higher QOL that did not differ as a function of racial bias or age. Similarly, females who reported low levels of racial bias had higher QOL that did not differ as a function of age. In contrast, females who reported high levels of racial bias had QOL that differed as a function of age. Specifically, older female children who reported high levels of perceived racial bias had poorer QOL (see Figure 1)

The Thioredoxin-Regulated α-Amylase 3 of Arabidopsis thaliana Is a Target of S-Glutathionylation

Reactive oxygen species (ROS) are produced in cells as normal cellular metabolic by-products. ROS concentration is normally low, but it increases under stress conditions. To stand ROS exposure, organisms evolved series of responsive mechanisms. One such mechanism is protein S-glutathionylation. S-glutathionylation is a post-translational modification typically occurring in response to oxidative stress, in which a glutathione reacts with cysteinyl residues, protecting them from overoxidation. α-Amylases are glucan hydrolases that cleave α-1,4-glucosidic bonds in starch. The Arabidopsis genome contains three genes encoding α-amylases. The sole chloroplastic member, AtAMY3, is involved in osmotic stress response and stomatal opening and is redox-regulated by thioredoxins. Here we show that AtAMY3 activity was sensitive to ROS, such as H2O2. Treatments with H2O2 inhibited enzyme activity and part of the inhibition was irreversible. However, in the presence of glutathione this irreversible inhibition was prevented through S-glutathionylation. The activity of oxidized AtAMY3 was completely restored by simultaneous reduction by both glutaredoxin (specific for the removal of glutathione-mixed disulfide) and thioredoxin (specific for the reduction of protein disulfide), supporting a possible liaison between both redox modifications. By comparing free cysteine residues between reduced and GSSG-treated AtAMY3 and performing oxidation experiments of Cys-to-Ser variants of AtAMY3 using biotin-conjugated GSSG, we could demonstrate that at least three distinct cysteinyl residues can be oxidized/glutathionylated, among those the two previously identified catalytic cysteines, Cys499 and Cys587. Measuring the pKa values of the catalytic cysteines by alkylation at different pHs and enzyme activity measurement (pKa1 = 5.70 ± 0.28; pKa2 = 7.83 ± 0.12) showed the tendency of one of the two catalytic cysteines to deprotonation, even at physiological pHs, supporting its propensity to undergo redox post-translational modifications. Taking into account previous and present findings, a functional model for redox regulation of AtAMY3 is proposed