Calibration and Irradiation Study of the BGO Background Monitor for the BEAST II Experiment

Beam commissioning of the SuperKEKB collider began in 2016. The Beam Exorcism for A STable experiment II (BEAST II) project is particularly designed to measure the beam backgrounds around the interaction point of the SuperKEKB collider for the Belle II experiment. We develop a system using bismuth germanium oxide (BGO) crystals with optical fibers connecting to a multianode photomultiplier tube (MAPMT) and a field-programmable gate array (FPGA) embedded readout board for monitoring the real-time beam backgrounds in BEAST II. The overall radiation sensitivity of this system is estimated to be $(2.20\pm0.26)\times10^{-12}$ Gy/ADU (analog-to-digital unit) with the standard 10 m fibers for transmission and the MAPMT operating at 700 V. Our $\gamma$-ray irradiation study of the BGO system shows that the exposure of BGO crystals to $^{60}$Co $\gamma$-ray doses of 1 krad has led to immediate light output reductions of 25--40%, and the light outputs further drop by 30--45% after the crystals receive doses of 2--4 krad. Our findings agree with those of the previous studies on the radiation hard (RH) BGO crystals grown by the low thermal gradient Czochralski (LTG Cz) technology. The absolute dose from the BGO system is also consistent with the simulation, and is estimated to be about 1.18 times the equivalent dose. These results prove that the BGO system is able to monitor the background dose rate in real time under extreme high radiation conditions. This study concludes that the BGO system is reliable for the beam background study in BEAST II

Image tag completion by local learning

The problem of tag completion is to learn the missing tags of an image. In this paper, we propose to learn a tag scoring vector for each image by local linear learning. A local linear function is used in the neighborhood of each image to predict the tag scoring vectors of its neighboring images. We construct a unified objective function for the learning of both tag scoring vectors and local linear function parame- ters. In the objective, we impose the learned tag scoring vectors to be consistent with the known associations to the tags of each image, and also minimize the prediction error of each local linear function, while reducing the complexity of each local function. The objective function is optimized by an alternate optimization strategy and gradient descent methods in an iterative algorithm. We compare the proposed algorithm against different state-of-the-art tag completion methods, and the results show its advantages

Sodium nitroprusside (SNP) alleviates the oxidative stress induced by NaHCO3 and protects chloroplast from damage in cucumber

Oxidative damage is often induced by abiotic stress, nitric oxide (NO) is considered as a functional molecule in modulating antioxidant metabolism of plants. In the present study, effects of sodium nitroprusside (SNP), a NO donor, on the phenotype, antioxidant capacity and chloroplast ultrastructure of cucumber leaves were studied under NaHCO3 stress. 30 mM NaHCO3 treatment significantly induced accumulation of H2O2 and thiobarbituric acid-reactive substances (TBARS) in cucumber leaves, and led to serious electrolyte leakage. Application of 100 μM SNP stimulated reactive oxygen species (ROS)- scavenging enzymes and increased antioxidant capacity, resulting in lower lipid peroxidation and membrane damage induced by NaHCO3 stress. As a main organelle of ROS formation, chloroplast ultrastructure was seriously damaged by NaHCO3 stress and SNP treatment obviously reversed the damage. On the contrary, the above effects of SNP were not observed by application of potassium ferrocyanide which is an analog of SNP that does not release NO. Therefore, it could be concluded that the NO from SNP might account for the alleviating effect of NaHCO3 stress on cucumber plants.Key words: Cucumber, alkaline stress, nitric oxide, antioxidant, chloroplast ultra structure

Comparison of PM2.5 carbonaceous pollutants between an urban site in Shanghai and a background site in a coastal East China Sea island in summer: concentration, composition and sources

Nine paired samples of atmospheric particulate matter with an aerodynamic diameter less than or equal to 2.5 μm (PM2.5) were collected concurrently from an urban site in Shanghai, China and a background site in Huaniao Island (HNI) in the coastal East China Sea (ECS) between July 21 and 29, 2011. The samples were analyzed for 16 United States Environmental Protection Agency (USEPA) priority polycyclic aromatic hydrocarbons (PAHs), n-alkanes (20 species, C14-C33), hopanes (10 species, C29-C32), and steranes (12 species, C27-C29). These two sites, approximately 66 km apart, are both on the pathway of land-based pollutants as they are transported to the ECS by seasonal winds. As expected, concentrations in Shanghai were higher (average: 8.4 and 67.8 ng m(-3) for the 16 PAHs and n-alkanes, respectively) than those in HNI (average: 1.8 and 8.5 ng m(-3), respectively). The dominant contributor to the 16 PAHs in Shanghai was 5-6-ring PAHs (60.0%), whereas 2-3-ring PAHs contributed the most (72.5%) in HNI. Plant waxes contributed 45.7% and 25.9% of the n-alkanes in Shanghai and HNI, respectively, implying a relatively greater contribution from petroleum residues to the n-alkanes in HNI. Principal component analysis (PCA) and the compositions of hopanes and steranes highlighted a prominent contribution from traffic emissions to carbonaceous PM2.5 aerosols. This study provides comprehensive details about the sources, formation, and transport of pollutants from eastern China to the coastal ECS

Betel quid chewing as a risk factor for hepatocellular carcinoma: a case-control study

The role of betel quid chewing in the aetiology of hepatocellular carcinoma (HCC) was evaluated in a case–control study including 263 pairs of age- and sex-matched HCC patients and healthy controls. Serum hepatitis B surface antigen (HBsAg), and antibodies to hepatitis C virus (anti-HCV) were determined, and standardized personal interview conducted using a structured questionnaire. Multivariate analysis indicated that betel quid chewing (odds ratio (OR), 3.49; 95% confidence interval (CI), 1.74–6.96), HBsAg (OR, 16.69; 95% CI, 9.92–28.07), anti-HCV (OR, 38.57; 95% CI, 18.15–81.96), and educational duration of less than 10 years (OR, 1.71; 95% CI, 1.05–2.78) are independent risk factors of HCC. In addition, there was an additive interaction between betel quid chewing and chronic infection with either hepatitis B virus (synergy index, 5.37) or hepatitis C virus (synergy index, 1.66). Moreover, risk on HCC increased as duration of betel quid chewing increased, or amount of betel quid consumed (each P for trend < 0.0001). © 2001 Cancer Research Campaign http://www.bjcancer.co

Time evolution, cyclic solutions and geometric phases for general spin in an arbitrarily varying magnetic field

A neutral particle with general spin and magnetic moment moving in an arbitrarily varying magnetic field is studied. The time evolution operator for the Schr\"odinger equation can be obtained if one can find a unit vector that satisfies the equation obeyed by the mean of the spin operator. There exist at least $2s+1$ cyclic solutions in any time interval. Some particular time interval may exist in which all solutions are cyclic. The nonadiabatic geometric phase for cyclic solutions generally contains extra terms in addition to the familiar one that is proportional to the solid angle subtended by the closed trace of the spin vector.Comment: revtex4, 8 pages, no figur