White spot syndrome virus inactivation study by using gamma irradiation

The present study was conducted to investigate the effect of gamma irradiation on white spot syndrome virus(WSSV). White spot syndrome virus is a pathogen of major economic importance in cultured penaeid shrimp industries. White spot disease can cause mortalities reaching 100% within 3–10 days of gross signs appearing. During the period of culture, immunostimulant agents and vaccines may provide potential methods to protect shrimps from opportunistic and pathogenic microrganisms. In this study, firstly, WSSV was isolated from infected shrimp and then multiplied in crayfish. WSSV was purified from the infected crayfish haemolymph by sucrose gradient and confirmed by transmission electron microscopy. In vivo virus titration was performed in shrimp, Penaeus semisulcatus. The LD50 of live virus stock was calculated 10 5.4 /mL. Shrimp post-larvae(1–2 g) were treated with gamma-irradiated(different doses) WSSV(10 0 to 10-4 dilutions) for a period of 10 days. The dose/survival curve for irradiated and un-irradiated WSSV was drawn; the optimum dose range for inactivation of WSSV and unaltered antigenicity was obtained 14–15 kGy. This preliminary information suggests that shrimp appear to benefit from treatment with gammairradiated WSSV especially at 14–15 KGy.     

批量变更技术在年度土地变更调查中的应用

从东莞市年度变更调查工作入手,分析变更调查数据的收集、整理、检查、处理流程,结合GIS技术,数据库技术,设计土地利用数据库批量变更技术。最后得出批量变更技术相对于单个图斑的变更在工作流程上和工作效率上的优势。     

基于聚集分形维数的旅游区空间结构测评与优化——以云南丽江市古城区为例

旅游区空间结构演化关系到旅游地的产业效应发挥,分形理论可以对景区(点)系统的空间结构进行科学的测评,从而为旅游地空间结构的优化提供相应的策略。以云南丽江古城区为实证,应用随机聚集分形理论对旅游景区(点)系统进行测算,研究发现:(1)以鱼米河商业步行街为中心的丽江古城区9 km2范围内旅游产业聚集效应呈现递减状况,9 km2以外的景区(点)呈现出离散状况;(2)丽江古城区旅游空间结构呈现出区域二元分异结构;(3)丽江古城区景区(点)总体布局具有一定的合理性,区域"一体两翼"发展模式具有较高的科学性。     

Arsenic in drinking and lung cancer mortality in Taiwan

The association between exposure to arsenic in drinking water and lung cancer has been observed in some epidemiology studies, but dose–response data are limited. To assess the dose–response relationship and identify hot spots, we analyzed the national death registry data of Taiwan from 1971 to 2000. We adopted data on 311 townships gathered by a nationwide survey of drinking water and divided arsenic levels into three groups: below 0.05 mg/L, 0.05–0.35 mg/L, and above 0.35 mg/L. Using the direct standardization method to adjust for the effects of age, we calculated the standardized mortality rates of lung cancer in both genders and evaluated their associations with arsenic levels. We also used the geographical information system to identify the hot spots. During the 30-year study period, we identified 64,954 male and 27,039 female lung cancer deaths in the study townships. We found significant increases in lung cancer mortality associated with arsenic levels above 0.35 mg/L in both genders, but the increases associated with levels between 0.05 and 0.35 mg/L were statistically significant in men only. Using both 0.05 and 0.35 mg/L as the cut-offs, we found most of the hot spots were in the southwestern coast and northeastern areas, but the southwestern coast area had some hot spots where the percentages of high risk population were higher than any hot spots in the northeastern area.     

The Butterfly Diagram Fine Structure

The present work describes the evolution of the sunspot zone in cycles 20, 21, and 22. In each cycle, and in both hemispheres, the equatorward drift of the spot zone “center of mass” results from the alternation of five or six prograde (namely, equatorward) segments, with other stationary or poleward segments. The duration of the stationary/retrograde phases (resulting from averaging data pertaining to the six semicycles examined here) amounts to ≈36% of the total duration of these semicycles. In the prograde phases, the drift rate is almost twice the “traditional” equatorward rate, resulting only from the extreme positions of the spot zone center of mass (at the beginning and at the end of the cycle). If there were no stationary/retrograde phases, the cycle duration would be half the actual one. We conclude that the retrograde phases should not be regarded as accidental; rather, they are essential features of the 11-year cycle.     

Spot activity in the RS CVn binary HR 1099

UBV photometry of HR 1099 obtained during the 1979-80 and 1980-81 observing seasons is presented. An analysis of the available data shows that the brightness at the light curve maximum increases as the wave amplitude increases, while the brightness at the light minimum remains almost the same. In terms of the starspot model it implies that there is always a hemisphere of the active component that is nearly ’saturated’ with spots and that spots occupy a larger fraction of the stellar surface when the wave amplitude is smaller. The continuous migration attributed to the photometric wave by various authors is far from certain. The amplitude of the wave has a sharp rise followed by slow decay with a period around 5–6 yr. It is found that the two-spot model proposed by Dorren and Guinan (1982) is inadequate to describe all the observed photometric peculiarities of HR 1099.     

气候突变:有关概念的介绍及一例分析—我国旱涝灾情的突变

本文介绍、评述了气候突变及其有关的一些概念,并应用突变检验方法对我国16个敏感性站点510年来旱涝灾情作了分析。     

地震散射波模拟成像方法在铜陵某矿区的应用

针对深部隐伏的金属矿床,以铜陵某矿区为例,应用散射波正演模拟技术,对金属矿地震数据野外采集中涉及的偏移距、覆盖次数、道间距等参数进行了不同炮记录的模拟对比,辅助指导非均匀地质体金属矿地震勘探野外数据采集的观测系统设计;针对该地区实际采集的地震数据,应用基于等效偏移距的共散射点成像方法,对金属矿地震数据进行了处理,通过与常规反射波法处理结果对比,散射成像效果较好,说明散射波技术在金属矿地震勘探中应用有一定的可行性和适用性.     

旅游对武夷山景区灌木林物种多样性及其根系生物量的影响

采用对比样方调查法对武夷山旅游区内的武夷宫、大红袍、龙川瀑布和天游峰4个典型景区灌木林物种多样性指数、均匀度和丰富度指数、植被盖度及根系生物量等指标进行了调查与分析,并对旅游活动对灌木林的影响机理进行了探讨.结果表明:旅游活动对景区灌木林物种多样性指数具有显著影响(Shannon-weiner均匀度指数除外),对林下根系生物量虽有影响,但影响不显著.干扰区的灌木林物种多样性指数、盖度、总根系及细根生物量均小于非干扰区.4景区灌木林的干扰变化率依次为:物种多样性指数为武夷宫>天游峰>龙川瀑布>大红袍,盖度为大红袍>武夷宫>天游峰>龙川瀑布.总根系生物量为天游峰>大红袍>龙川瀑布>武夷宫,细根生物量为天游峰>龙川瀑布>武夷宫>大红袍.