Time and Amplitude of Afterpulse Measured with a Large Size Photomultiplier Tube

We have studied the afterpulse of a hemispherical photomultiplier tube for an upcoming reactor neutrino experiment. The timing, the amplitude, and the rate of the afterpulse for a 10 inch photomultiplier tube were measured with a 400 MHz FADC up to 16 \ms time window after the initial signal generated by an LED light pulse. The time and amplitude correlation of the afterpulse shows several distinctive groups. We describe the dependencies of the afterpulse on the applied high voltage and the amplitude of the main light pulse. The present data could shed light upon the general mechanism of the afterpulse.Comment: 11 figure

Superstrings on NS5 backgrounds, deformed AdS3 and holography

We study a non-standard decoupling limit of the D1/D5-brane system, which interpolates between the near-horizon geometry of the D1/D5 background and the near-horizon limit of the pure D5-brane geometry. The S-dual description of this background is actually an exactly solvable two-dimensional (worldsheet) conformal field theory: {null-deformed SL(2,R)} x SU(2) x T^4 or K3. This model is free of strong-coupling singularities. By a careful treatment of the SL(2,R), based on the better-understood SL(2,R) / U(1) coset, we obtain the full partition function for superstrings on SL(2,R) x SU(2) x K3. This allows us to compute the partition functions for the J^3 and J^2 current-current deformations, as well as the full line of supersymmetric null deformations, which links the SL(2,R) conformal field theory with linear dilaton theory. The holographic interpretation of this setup is a renormalization-group flow between the decoupled NS5-brane world-volume theory in the ultraviolet (Little String Theory), and the low-energy dynamics of super Yang--Mills string-like instantons in six dimensions.Comment: JHEP style, 59 pages, 1 figure; v2: minor changes, to appear in JHE

Physics Opportunities with the 12 GeV Upgrade at Jefferson Lab

This white paper summarizes the scientific opportunities for utilization of the upgraded 12 GeV Continuous Electron Beam Accelerator Facility (CEBAF) and associated experimental equipment at Jefferson Lab. It is based on the 52 proposals recommended for approval by the Jefferson Lab Program Advisory Committee.The upgraded facility will enable a new experimental program with substantial discovery potential to address important topics in nuclear, hadronic, and electroweak physics.Comment: 64 page

Buoyancy induced convective flow in porous media with heat source

An unbounded fluid layer in a porous medium with an internal heat source and uniformly heated from below is studied. The layer is in the gravitational field. Linear theory predicts that the disturbances of infinitesimal amplitude will start to grow when the Rayleigh number exceeds its critical value. These disturbances do not grow without limit; but by advecting heat and momentum, the disturbances alter their forms to achieve a finite amplitude. Just like infinitesimal amplitude disturbances the degeneracies of possible solutions persist for finite amplitude solutions. This study evaluates these various forms of solutions. The small parameter method of Poincare is used to treat the problem in successive order

Spirulina Prevents Memory Dysfunction, Reduces Oxidative Stress Damage and Augments Antioxidant Activity in Senescence-Accelerated Mice

Spirulina has proven to be effective in treating certain cancers, hyperlipidemia, immunodeficiency, and inflammatory processes. In this study, we aimed to investigate the effects of Spirulina on memory dysfunction, oxidative stress damage and antioxidant enzyme activity. Three-month-old male senescence-accelerated prone-8 (SAMP8) mice were randomly assigned to either a control group or to one of two experimental groups (one receiving daily dietary supplementation with 50 mg/kg BW and one with 200 mg/kg BW of Spirulina platensis water extract). Senescence-accelerated-resistant (SAMR1) mice were used as the external control. Results showed that the Spirulina-treated groups had better passive and avoidance scores than the control group. The amyloid beta-protein (A beta) deposition was significantly reduced at the hippocampus and whole brain in both Spirulina groups. The levels of lipid peroxidation were significantly reduced at the hippocampus, striatum, and cortex in both Spirulina groups, while catalase activity was significantly higher only in the 200 mg/kg BW Spirulina group than in the control group. Glutathione peroxidase activity was significantly higher only in the cortex of the 200 mg/kg group than in that of the SAMP8 control group. However, superoxide dismutase activity in all parts of the brain did not significantly differ among all groups. In conclusion, Spirulina platensis may prevent the loss of memory possibly by lessening A beta protein accumulation, reducing oxidative damage and mainly augmenting the catalase activity

A Compact Design of Tunable Band-Notched Ultra-Wide Band Antenna

In this letter, a compact ultrawideband planar inverted F‐L antenna with a tunable band‐notched response is presented. Tuning of the rejected frequency bands is realized by loading a variable capacitor on an embedded slot of the proposed antenna structure. The antenna exhibits a wide impedance bandwidth from 3.1 to 10.6 GHz with a good impedance matching (voltage standing wave ratio ≤ 2) and tunable broad range of band‐reject frequency (centre frequency from 3.2 to 6 GHz). To validate the theoretical model and design concept, the antenna prototype was fabricated and measured

A frequency tunable PIFA design for handset applications

A frequency tunable planar inverted F antenna (PIFA) is presented for use in the following bands: DCS, PCS, and UMTS. Initially, the tuning was achieved by placing a lumped capacitor, with values in the range of 1.5 to 4 pF, along the slot of the radiator. The final tuning circuit uses a varactor diode, and discrete lumped elements are fully integrated with the antenna. The antenna prototype is tunable over from 1850 MHz to 2200 MHz, with an associated volume of 21×13.5×5 mm3, making it suitable for potential integration in a commercial handset or mobile user terminal

Phytophthora fruit rot of peach in Taiwan

一九九九年六月至七月間台中石岡一鶯歌桃果園的果實採收後，於儲運期問發生嚴重腐敗現象。罹病果實初現淡褐色水浸狀圓形斑點，病斑面積迅速擴大轉為暗褐色，並長出白色密緻的黴狀物。經組織分離，共獲得兩種疫病菌，分別為Phytophthora meadii與P. citrophthora，將兩種疫病菌的游走子接種於鶯歌桃果實，2-3天後均會造成果實腐敗，病徵與儲運期間發生者一致，證明此種桃果實腐敗係由疫病菌引起。此外，自罹病果園與鄰近碰柑園內的落果、根系與土壤中，均可以分離至到P. citrophthora。由於農民於果實採收後曾以水清洗所有果實，而果實於2-3天內嚴重發病，因此推測桃果實發病原因，為少數罹病果實上的胞囊於清洗過程中釋放人量游走子成為二次感染源，再侵染其他健康果實所致。採收時如將病果剔除，並在清洗水中加人10 ppm次氯酸鈉，可有效防治該病害。兩種疫病菌有部份特性相似，包括菌絲生長溫度為8-32℃，最適溫為20-28℃；胞囊具顯著乳突及脫落性，胞囊柄長中等，平均約為9 11 m，均不形成厚膜胞子。兩者的相異處為P. meadii的胞囊較長，長寬比值平均約為1.5-1.6，而P. citrophthora者較短，約為1.3；其中P. meadii均為A2配對型，本身會形成卵胞子(self-oospores)；而P. citrophthora為A1配對型，但本身不會形成卵胞子。當兩者直接配對時亦無卵胞子產生。此外，兩菌的菌絲蛋白質電泳圖譜相近，僅有些微差異。在台灣，疫病菌危害鶯歌桃果實為首度報導，而P. meadii危害桃樹為世界首度發現。 Peach (Prunus persica) fruit, harvested from an orchard located at Shigang, Taichung County, occurred a serious disease in 1999. Light brown water-soaking spots appeared on affected fruit at the early stage. The diseased areas turned brown and soft, and were covered with a thick layer of white mold subsequently under high moist condition. Phytophthora meadii and P. citrophthora were isolated from diseased fruit. Disease symptoms similar to those appeared in the field and market were reproduced on the fruit 2-3 days after inoculation with zoospore suspension of each Phytophthora isolate tested. The same fungi were reisolated from all of the inoculated diseased fruit. Since all harvested fruit were washed with the water collected from a ditch nearby and most disease symptoms appeared within 2-3 days in the market, the severe Phytophthora fruit rot of peach might be a result of zoospore infection during the washing process. P. citrophthora was frequently isolated from the fibrous roots and rhizosphere soil of peach plants as well as the dropped citrus fruits, roots and soil in an adjacent ponkan orchard. It was considered possible that the diseased fruit from the field produced large amount of zoospores in the wash water, severing as secondary inoculum to infect other health fruit. Removing diseased fruits combined with adding 10 ppm NaClO into the washing water was highly effective in controlling the Phytophthora brown rot disease. Some characteristics of the two Phytophthora species from peach were similar. Both species were able to grow on V-8 agar between 8-32 with the optimum growth temperature of 20-28 . Sporangia of both species had semi-spherical papilla and were deciduous with pedicel length about 9-11 m in average. Chlamydospores were absent. However, the colony patterns of the two species grown on V-8 agar and PDA were different. Sporangia of P. meadii isolates (L/B ratio of 1.5-1.6) were much longer than those of P. citrophthora isolates with L/B ratio of 1.3. All of the peach isolates of P. meadii belonged to A2 mating type, which formed self-oospores while paired with A1 type of P. parasitica and vice versa. All P. citrophthora isolates were A1 type, which stimulated A2 type of P. parasitica to form oospores but didn't form self-oospores themselves. Sex organs were not produced when these two species were paired directly. The mycelial soluble protein patterns of isolates of both species analyzed by SDS PAGE electrophoresis were similar but with some difference. This is the first report of peach Phytophthora fruit rot in Taiwan. To our best knowledge, this is also the first report of peach fruit disease caused by P. meadii in the world