The Presampler for the Forward and Rear Calorimeter in the ZEUS Detector

The ZEUS detector at HERA has been supplemented with a presampler detector in front of the forward and rear calorimeters. It consists of a segmented scintillator array read out with wavelength-shifting fibers. We discuss its desi gn, construction and performance. Test beam data obtained with a prototype presampler and the ZEUS prototype calorimeter demonstrate the main function of this detector, i.e. the correction for the energy lost by an electron interacting in inactive material in front of the calorimeter.Comment: 20 pages including 16 figure

Differential Redox Regulation of ORAI Ion Channels: A Mechanism to Tune Cellular Calcium Signaling

Reactive oxygen species (ROS) are involved in many physiological and pathophysiological cellular processes. We used lymphocytes, which are exposed to highly oxidizing environments during inflammation, to study the influence of ROS on cellular function. Calcium ion (Ca2+) influx through Ca2+ release–activated Ca2+ (CRAC) channels composed of proteins of the ORAI family is essential for the activation, proliferation, and differentiation of T lymphocytes, but whether and how ROS affect ORAI channel function have been unclear. Here, we combined Ca2+ imaging, patch-clamp recordings and measurements of cell proliferation and cytokine secretion to determine the effects of hydrogen peroxide (H2O2) on ORAI channel activity and human T helper lymphocyte (TH cell) function. ORAI1, but not ORAI3, channels were inhibited by oxidation by H2O2. The differential redox sensitivity of ORAI1 and ORAI3 channels depended mainly on an extracellularly located reactive cysteine, which is absent in ORAI3. TH cells became progressively less redox-sensitive after differentiation into effector cells, a shift that would allow them to proliferate, differentiate, and secrete cytokines in oxidizing environments. The decreased redox sensitivity of effector TH cells correlated with increased expression of Orai3 and increased abundance of several cytosolic antioxidants. Knockdown of ORAI3 with small-interfering RNA rendered effector TH cells more redox-sensitive. The differential expression of Orai isoforms between naïve and effector TH cells may tune cellular responses under oxidative stress

Inverse Association between trans Isomeric and Long-Chain Polyunsaturated Fatty Acids in Pregnant Women and Their Newborns: Data from Three European Countries

Background: trans unsaturated fatty acids are thought to interfere with essential fatty acid metabolism. To extend our knowledge of this phenomenon, we investigated the relationship between trans isomeric and long-chain polyunsaturated fatty acids (LCPUFA) in mothers during pregnancy and in their infants at birth. Methods: Fatty acid composition of erythrocyte phosphatidylcholine (PC) and phosphatidylethanolamine (PE) was determined in Spanish (n = 120), German (n = 78) and Hungarian (n = 43) women at the 20th and 30th week of gestation, at delivery and in their newborns. Results: At the 20th week of gestation, the sum of trans fatty acids in PE was significantly (p < 0.01) lower in Hungarian [0.73 (0.51), % wt/wt, median (IQR)] than in Spanish [1.42 (1.36)] and German [1.30 (1.21)] women. Docosahexaenoic acid (DHA) values in PE were significantly (p < 0.01) higher in Hungarian {[}5.65 (2.09)] than in Spanish [4.37 (2.60)] or German [4.39 (3.3.2)] women. The sum of trans fatty acids significantly inversely correlated to DHA in PCs in Spanish (r = -0.37, p < 0.001), German (n = -0.77, p < 0.001) and Hungarian (r = -0.35, p < 0.05) women, and in PEs in Spanish (r = -0.67, p < 0.001) and German (r = -0.71, p < 0.001), but not in Hungarian (r = -0.02) women. Significant inverse correlations were seen between trans fatty acids and DHA in PEs at the 30th week of gestation (n = 241, r = -0.52, p < 0.001), at delivery (n = 241, r = -0.40, p < 0.001) and in cord lipids (n = 218, r = -0.28, p < 0.001). Conclusion: Because humans cannot synthesize trans isomeric fatty acids, the data obtained in the present study support the concept that high maternal trans isomeric fatty acid intake may interfere with the availability of LCPUFA both for the mother and the fetus. Copyright (C) 2011 S. Karger AG, Base

Dynamics, Patterns and Causes of Fires in Northwestern Amazonia

According to recent studies, two widespread droughts occurred in the Amazon basin, one during 2005 and one during 2010. The drought increased the prevalence of climate-driven fires over most of the basin. Given the importance of human-atmosphere-vegetation interactions in tropical rainforests, these events have generated concerns over the vulnerability of this area to climate change. This paper focuses on one of the wettest areas of the basin, Northwestern Amazonia, where the interactions between the climate and fires are much weaker and where little is known about the anthropogenic drivers of fires. We have assessed the response of fires to climate over a ten-year period, and analysed the socio-economic and demographic determinants of fire occurrence. The patterns of fires and climate and their linkages in Northwestern Amazonia differ from the enhanced fire response to climate variation observed in the rest of Amazonia. The highest number of recorded fires in Northwestern Amazonia occurred in 2004 and 2007, and this did not coincide with the periods of extreme drought experienced in Amazonia in 2005 and 2010. Rather, during those years, Northwestern Amazonia experienced a relatively small numbers of fire hotspots. We have shown that fire occurrence correlated well with deforestation and was determined by anthropogenic drivers, mainly small-scale agriculture, cattle ranching (i.e., pastures) and active agricultural frontiers (including illegal crops). Thus, the particular climatic conditions for air convergence and rainfall created by proximity to the Andes, coupled with the presence of one of the most active colonisation fronts in the region, make this region differently affected by the general drought-induced fire patterns experienced by the rest of the Amazon. Moreover, the results suggest that, even in this wet region, humans are able to modify the frequency of fires and impact these historically well preserved forests

Response of Cocoa Trees (Theobroma cacao) to a 13-month Dessication Period in Sulawesi, Indonesia

In South-east Asia, ENSO-related droughts represent irregularly occuring hazards for agroforestry systems containing cocoa which are predicted to increase in severity with expected climate warming. To characterize the drought response of mature cocoa tree, we conducted the Sulawesi Throughfall Displacement Experiment in a shaded (Gliricidia sepium) cocoa agroforestry system in Central Sulawesi, Indonesia. Three large sub-canopy roofs were installed to reduce throughfall by about 80% over a 13-month period to test the hypotheses that (i) cocoa trees are sensitive to drought due to their shallow fine root system, and (ii)bean yield is more sensitive to drought than leaf or stem growth. As 83% of fine root (diameter 2mm) was located in the upper 40 cm of the soil, the cocoa tree examined had a very shallow root system. Cocoa and Gliricidia differed in their vertical rooting patterns, thereby reducing competition for water. Despite being exposed for several mnths to soil water contents close to the conventional wilting point, cocoa trees showed no significant decreases in leaf biomass, stem and branch wood production or fine root biomass. Possible causes are active osmotic adjusment in roots, mitigation of drought stress by shading from Gliricidia or other factors. By contrast, production of cocoa bean

The contribution of tropical cyclones to the atmospheric branch of Middle America's hydrological cycle using observed and reanalysis tracks

Middle America is affected by tropical cyclones (TCs) from the Eastern Pacific and the North Atlantic Oceans. We characterize the regional climatology (1998-2016) of the TC contributions to the atmospheric branch of the hydrological cycle, from May to December. TC contributions to rainfall are quantified using Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) product 3B42 and TC tracks derived from three sources: the International Best Track Archive for Climate Stewardship (IBTrACS), and an objective feature tracking method applied to the Japanese 55-year and ERA-Interim reanalyses. From July to October, TCs contribute 10-30% of rainfall over the west and east coast of Mexico and central Mexico, with the largest monthly contribution during September over the Baja California Peninsula (up to 90%). TCs are associated with 40-60% of daily extreme rainfall (above the 95th percentile) over the coasts of Mexico. IBTrACS and reanalyses agree on TC contributions over the Atlantic Ocean but disagree over the Eastern Pacific Ocean and continent; differences over the continent are mainly attributed to discrepancies in TC tracks in proximity to the coast and TC lifetime. Reanalysis estimates of TC moisture transports show that TCs are an important moisture source for the regional water budget. TC vertically integrated moisture flux (VIMF) convergence can turn regions of weak VIMF divergence by the mean circulation into regions of weak VIMF convergence. We discuss deficiencies in the observed and reanalysis TC tracks, which limit our ability to quantify robustly the contribution of TCs to the regional hydrological cycle