(C) 2013 Elsevier Ltd. All rights reserved.”
“The Hall resistance of small Hall sensors and its nonlinear dependence on magnetic field B were investigated at the temperature of 4.2 K. The sensors were four-terminal crosses fabricated by etching AlGaAs/InGaAs/GaAs delta-doped heterostructures. While large sensors exhibit

good linearity of the Hall voltage on magnetic field, in sensors smaller than 5 mu m we detected pronounced nonlinearities for magnetic fields between 0 and 2 T. We attribute the latter to ballistic corrections this website to the classical Hall effect, and we model the Hall and the bend resistances at low temperature using Monte Carlo simulation. We also carried out temperature studies of the Hall sensors. We show that the nonlinearities persist up to room temperature. The effect of nonlinearities on the performance of Hall sensors is discussed. (C) 2009 American Institute of Physics. [DOI: 10.1063/1.3103303]“
“The World Health Organization (WHO) Air Quality Guidelines (AQG) were launched in 2006, but gaps remain in evidence on health impacts and relationships between short-term and annual AQG needed for health protection. We tested whether relationships between WHO short-term and annual AQG for particulates (PM10 and PM2.5)

and nitrogen dioxide (NO2) are concordant worldwide and derived the annual limits for sulfur dioxide (SO2) and ozone (O-3) based on the short-term AQG. We obtained air pollutant data over seven years (2004-2010) in seven cities selleck screening library from Asia-Pacific, North America and Europe. Based on probability distribution concept using maximum as the short-term limit and arithmetic mean as the annual limit, we developed a new method to derive limit value one from another in each paired limits for each pollutant with capability to account for allowable exceedances. We averaged the limit derived each year for each city, then

used meta-analysis to pool the limit values in all cities. Pooled mean short-term limit for NO2 (140.5 mu g/m(3) [130.6-150.4]) was significantly lower than the WHO AQG of 200 mu g/m(3) while for PM10 (46.4 mu g/m(3) [95CI:42.1-50.7]) and PM2.5 (28.6 mu g/m(3) [24.5-32.6]) were not significantly different from the WHO AQG of 50 check details and 25 mu g/m(3) respectively. Pooled mean annual limits for SO2 and O-3 were 4.6 mu g/m(3) [3.7-5.5] and 27.0 mu g/m(3) [21.7-32.2] respectively. Results were robust in various sensitivity analyses. The distribution relationships between the current WHO short-term and annual AQG are supported by empirical data from seven cities for PM10 and PM2.5, but not for NO2. The short-term AQG for NO2 should be lowered for concordance with the selected annual AQG for health protection. (C) 2013 The Authors. Published by Elsevier Ltd. All rights reserved.