Electromagnetic Compatibility Testing Studies

This report discusses the results on analytical models and measurement and simulation of statistical properties from a study of microwave reverberation (mode-stirred) chambers performed at Texas Tech University. Two analytical models of power transfer vs. frequency in a chamber, one for antenna-to-antenna transfer and the other for antenna to D-dot sensor, were experimentally validated in our chamber. Two examples are presented of the measurement and calculation of chamber Q, one for each of the models. Measurements of EM power density validate a theoretical probability distribution on and away from the chamber walls and also yield a distribution with larger standard deviation at frequencies below the range of validity of the theory. Measurements of EM power density at pairs of points which validate a theoretical spatial correlation function on the chamber walls and also yield a correlation function with larger correlation length, R(sub corr), at frequencies below the range of validity of the theory. A numerical simulation, employing a rectangular cavity with a moving wall shows agreement with the measurements. The determination that the lowest frequency at which the theoretical spatial correlation function is valid in our chamber is considerably higher than the lowest frequency recommended by current guidelines for utilizing reverberation chambers in EMC testing. Two suggestions have been made for future studies related to EMC testing

Can 2 apples a day improve cardiovascular and gut health?

n/

Water Quality Sampling, Analysis and Annual Load Determinations for TSS, Nitrogen and Phosphorus in the Bayou Bartholomew at Garrett Bridge, Arkansas and Near Portland, Arkansas

Water quality sampling stations were installed at the Bayou Bartholomew at Garrett Bridge, AR and near Portland, AR. These stations are coordinated with USGS gauging stations at the same locations. These stations are instrumented to collect samples at sufficient intervals across the hydrograph to accurately estimate the flux of total suspended solids, nitrogen and phosphorus in the River. Bayou Bartholomew watershed is about 437,000 hectares and is located in the south east corner of the state. The land use in the watershed is mostly in forest and cropland agriculture with some urban area. High turbidity levels and excessive silt loads in the streams are problems in this watershed. The reason for high turbidity levels and silt loads are thought to be row crop agriculture. Accurate determination of stream nutrients and sediment is critical for future determinations of TMDLs, effectiveness of best management practices and trends in water quality

Water Quality Sampling, Analysis and Annual Load Determinations for TSS, Nitrogen and Phosphorus at the L\u27Anguille River Near Palestine 2005 Annual Report

A water quality sampling station was installed at the L’Anguille River near Palestine in 2003. This station is coordinated with a USGS gauging station at the same location. This station is instrumented to collect samples at sufficient intervals across the hydrograph to accurately estimate the flux of total suspended solids, nitrogen and phosphorus in the River. The L’Anguille River was listed on Arkansas\u27 1998 (listed in later reports?) 303d list as impaired from sediment (turbidity). The L’Anguille River was the second stream to have total maximum daily loads (TMDL) determined in Arkansas. Accurate determination of stream nutrients and sediment is critical for future determinations of TMDLs, effectiveness of best management practices and trends in water quality

The effects of active classroom breaks on moderate to vigorous physical activity, behaviour and performance in a Northern NSW primary school: A quasi-experimental study

Issue Addressed: Approximately 77% of NSW children aged 5 to 15 years do not meet physical activity guidelines and many spend a considerable amount of time sitting. Active breaks at primary school are feasible, may increase daily moderate to vigorous physical activity (MVPA) and decrease off-task behaviour without adversely affecting cognitive function and learning. Methods: In this quasi-experimental study, 101 primary school children in six intervention classrooms participated in three 10-minute active breaks per day for six-weeks during class time, while five control classrooms were run as usual (n = 89). Physical activity levels were measured using wrist-worn Actigraph wGT3X-BT accelerometers and analysed using a random forest model. Students' off-task behaviour, wellbeing, cognitive function and maths performance were also measured. School staff completed a brief feedback survey. Results: Children in the intervention group engaged in 15.4 and 10.9 minutes more MVPA per day at 3 and 6 weeks respectively (P <.001). Participation significantly increased the proportion of children who met the Australian 24-Hour Movement Guidelines (P <.001). At pre, middle and end of intervention, 44.4%, 60.8% and 55.1% of intervention children and 46.5%, 45.9% and 45.8% of controls met the guidelines. Significantly fewer students engaged in off-task behaviour in the intervention classes at mid and final weeks of intervention (−1.4 students, P =.003). No significant intervention effects were found for wellbeing, cognitive and maths performance. Conclusions: Active classroom breaks are an effective way to increase physical activity among primary school children while reducing off-task classroom behaviour. So What?: Primary school students' health would benefit from active breaks with no detrimental effects on wellbeing, maths and cognitive performance

Investigating optimal accelerometer placement for energy expenditure prediction in children using a machine learning approach

Accurate measurement of energy expenditure (EE) is imperative for identifying and targeting health-associated implications. Whilst numerous accelerometer-based regression equations to predict EE have been developed, there remains little consensus regarding optimal accelerometer placement. Therefore, the purpose of the present study was to validate and compare artificial neural networks (ANNs) developed from accelerometers worn on various anatomical positions, and combinations thereof, to predict EE.Twenty-seven children (15 boys; 10.8  ±  1.1 years) participated in an incremental treadmill test and 30 min exergaming session wearing a portable gas analyser and nine ActiGraph GT3X+  accelerometers (chest and left and right wrists, hips, knees, and ankles). Age and sex-specific resting EE equations (Schofield) were used to estimate METs from the oxygen uptake measures. Using all the data from both exergames, incremental treadmill test and the transition period in between, ANNs were created and tested separately for each accelerometer and for combinations of two or more using a leave-one-out approach to predict EE compared to measured EE. Six features (mean and variance of the three accelerometer axes) were extracted within each 15 s window as inputs in the ANN. Correlations and root mean square error (RMSE) were calculated to evaluate prediction accuracy of each ANN, and repeated measures ANOVA was used to statistically compare accuracy of the ANNs.All single-accelerometer ANNs and combinations of two-, three-, and four-accelerometers performed equally (r  =  0.77–0.82), demonstrating higher correlations than the 9-accelerometer ANN (r  =  0.69) or the Freedson linear regression equation (r  =  0.75). RMSE did not differ between single-accelerometer ANNs or combinations of two, three, or four accelerometers (1.21–1.31 METs), demonstrating lower RMSEs than the 9-accelerometer ANN (1.46 METs) or Freedson equation (1.74 METs).These findings provide preliminary evidence that ANNs developed from single accelerometers mounted on various anatomical positions demonstrate equivalency in the accuracy to predict EE in a semi-structured setting, supporting the use of ANNs in improving EE prediction accuracy compared with linear regression

Phosphine-Catalyzed Formation of Carbon-Sulfur Bonds: Catalytic Asymmetric Synthesis of gamma-Thioesters

Supporting Information Available: Experimental procedures and compound characterization data. This material is available free of charge via the Internet at http://pubs.acs.org.A method for catalytic asymmetric γ sulfenylation of carbonyl compounds has been developed. In the presence of an appropriate catalyst, thiols not only add to the γ position of allenoates, overcoming their propensity to add to the β position in the absence of a catalyst, but do so with very good enantioselectivity. Sulfur nucleophiles are now added to the three families of nucleophiles (carbon, nitrogen, and oxygen) that had earlier been shown to participate in catalyzed γ additions. The phosphine catalyst of choice, TangPhos, had previously only been employed as a chiral ligand for transition metals, not as an efficient enantioselective nucleophilic catalyst.National Institutes of Health (U.S.)National Institute of General Medical Sciences (U.S.) (R01-GM57034)Merck & Co.Novartis (Firm