临沂地区1956-2002年流行性脑脊髓膜炎的流行病学分析

目的:分析临沂地区1956-2002年流行性脑脊髓膜炎的流行趋势,探讨该地区流脑发病率与气象因素的关系。方法:收集临沂地区自1956年至2002年间流行性脑脊髓膜炎的逐月发病资料及同时期气象资料,分析流脑发病率的长期变化趋势、周期性和季节性特点;并分析流行强度与平均气温、平均气压、相对湿度、降雨量、日照时数、平均风速等气象因素的相关性。结果:1956-2002年临沂地区流行性脑脊髓膜炎病例共计220067例,截至到1982年12月共有216694例,占总病例数的98.47%;自1983年开始,每年流脑发病率明显降低。流脑发病以2-4月为发病高峰期。某些月份流脑的发病率与气温和风速呈现明显的负相关。结论:流脑的发病具有明显的季节性,且与某些气象因素具有一定的相关性。流脑疫苗的应用有效的降低了临沂地区流脑的发病率。     

影响武夷山景区松墨天牛种群动态变化的因素分析

为了监测武夷山景区松墨天牛Monochamus alternatus Hope的发生,防范松材松材线虫Bursaphelonchus xylophilus病的入侵,于2005-2007年每年4-9月,在武夷山景区10个地点进行了调查,研究了气象因素和环境因素对松墨天牛数量变化的综合影响规律及其程度,对调查结果进行了矢量递进因子分析。结果表明：环境因子和气象因子是松墨天牛羽化孔数和诱集成虫数变化的主要因素,影响松墨天牛成虫诱集数的环境因子按重要性排列依次为：郁闭度、地被物覆盖率、海拔、林龄、坡位、坡向和树高;影响羽化孔数的环境因子按重要性排列依次为：郁闭度、地被物覆盖率、树高、林龄、海拔、坡位和坡向。影响松墨天牛诱集成虫数和羽化孔数的气象因子按重要性排列依次为：月平均温度、最高与最低温差、总降雨量（mm）、气压（hpa）和平均湿度（%）。单从环境因子和气象因子的统计数据分析,环境因子的重要性次序是：坡位、郁闭度、地被物覆盖率、海拔（m）、 林龄（a）、树高（m）、坡向;气象因子的重要性次序是：气压（hpa）、 平均温度 （℃）、最高与最低温差（℃）、 总降雨量（mm）、平均湿度（%）。按月分析和按年度分析时其相对重要性基本上是一致的。结论认为,环境因子和气象因子对松墨天牛的数量变化有重要影响。     

益生菌制剂治疗2型糖尿病临床疗效的Meta分析

目的 系统评价益生菌制剂对2型糖尿病（T2DM）患者空腹血糖、脂质代谢以及应激反应的影响。方法 计算机检索 PubMed、Embase、The Cochrane Library、中国知网、维普期刊数据库和万方数据库。筛选关于糖尿病患者添加益生菌制剂相关性研究的中英文随机对照试验（RCT）,进行纳入文献的资料提取和质量评价,采用RevMan 5.3软件进行Meta分析。对比益生菌组与对照组患者空腹血糖（FPG）、糖化血红蛋白（HbA1c）、甘油三酯（TG）、胆固醇（TC）和C反应蛋白（CRP）指标。结果 共纳入17项符合标准的RCTs,Meta分析结果显示：与对照组患者相比,益生菌制剂可显著降低T2DM患者FPG（SMD=‒0.43,95% CI:‒0.57～‒0.28,P<0.00001）、HbA1c（SMD=‒0.47, 95% CI:‒0.82～‒0.12,P=0.009）和TG（SMD=‒0.31,95% CI:‒0.51～‒0.11,P=0.002）水平;TC（SMD=‒0.63,95% CI:‒1.46～0.20,P=0.13）、CRP（SMD=‒0.59,95% CI:‒1.41～0.22,P=0.15）在两组患者之间差异无统计学意义。结论 益生菌制剂可改善T2DM患者血糖、血脂状况。     

石榴园西花蓟马种群动态及其与气象因素的关系

2007-2008年,对云南省建水石榴园西花蓟马种群动态进行了系统调查,并采用回归分析(逐步回归分析、通径分析)、主成分分析及灰色系统分析就气象因子对该虫种群动态的影响进行了系统分析。结果表明,西花蓟马在建水石榴园常年发生,冬季较低,夏季最高,成虫全年种群消长呈单峰型,高峰期为5月份。相关性分析结果表明,西花蓟马种群数量与月相对湿度间呈极显著正相关性(P<0.01),与月均气温和月最低气温间呈显著正相关性(P<0.05),与月最高气温、月均降雨量和月均蒸发量间无相关性(P>0.05)。回归分析结果表明,石榴园西花蓟马种群动态的决定因子中影响最大的气象因素是月最低气温,而月均气温和月相对湿度是影响种群数量变动的主要因素。主成分分析表明,月最低气温是主要成分,其累积方差贡献率达73.03%。灰色系统分析结果表明,影响石榴园6种蓟马种群动态最关键的因子是月相对湿度;年度间影响最大的是年总降雨量;石榴花期各蓟马的种群数量与气象因素间关联度最大的是月最低温;果期各种蓟马的种群数量与气象因素间关联度最大的是月均降雨量。     

杭州湾北部安氏白虾的繁殖生物学特征

采用2017年4月至2018年3月张网逐月采样数据分析杭州湾北部安氏白虾（Palaemon annandalei）的繁殖生物学特征。结果显示,安氏白虾体平均体长（32.0 ± 5.4）mm（14 ~ 51 mm,n = 3 210）,抱卵群体平均体长（36.3 ± 3.4）mm（27 ~ 51 mm,n = 375）。体重分布范围为0.016 ~ 1.700 g,n = 3 210,平均体重（0.565 ± 0.282）g,抱卵群体体重分布范围为0.400 ~ 1.700 g,n = 375,平均体重（0.868 ± 0.225）g。雌、雄个体间平均体长和平均体重都具有显著性差异（P < 0.01）;雌雄性比为1.27︰1,雌性个体数显著多于雄性个体数（P < 0.01）。繁殖期从4月下旬一直持续至10月下旬,6月和8月为两个繁殖旺期,抱卵率（B）和性比（S）具有显著线性相关关系（P < 0.05）,关系式为B = 41.80S﹣21.06（R2 = 73.9）。绝对繁殖力为17 ~ 179粒,平均绝对繁殖力（60 ± 26）粒,平均相对繁殖力（70 ± 24）粒/g,n = 375。绝对繁殖力（FA,单位粒）与体长（L,单位mm）、体重（W,单位g）均呈二次函数显著相关（P < 0.01）,关系式分别为FA = 0.29L2﹣18.52L + 342.67（R2 = 76.8）和FA = 97.32W2 ﹣100.75W + 71.66（R2 = 94.5）。卵长径分布范围为1.090 ~ 2.688 mm,平均长径（1.599 ± 0.158）mm,短径分布范围0.807 ~ 1.992 mm,平均短径（1.141 ± 0.118）mm,n = 2 787。研究表明,与20世纪80年代相比,安氏白虾个体朝小型化方向发展,繁殖周期延长,繁殖旺期由单峰型变为双峰型,这可能是生态环境持续恶化和高强度捕捞压力所致。     

花椒园节肢动物群落特征与气象因子的关系

分析了云南永善县金沙江畔花椒园节肢动物群落特征与园内最低温度、平均温度、最高温度、最低湿度、平均湿度、最高湿度及月降雨量等7个气象因子的关系。结果表明:节肢动物群落个体数、物种数受最低湿度变化影响最大,表现为正相关的变化趋势;群落多样性、均匀度、丰富度指数变化与最高温度、最高湿度变化的关联度较大,表明节肢动物群落在相对较高的温、湿度环境下具有更高的群落多样性、丰富度及均匀度;优势集中性及优势度指数变化与最高温度、最低湿度变化的关联度较大,表明优势种类在高温或低湿环境下更易出现;稳定性S_s/S_i、S_n/S_p指数与平均湿度的关联度较大,表明适度的湿度变化范围更利于增强群落物种间数量上的制约作用。降雨量对群落特征的影响最小,在月均降雨量小于99.3 mm的3-6月、9月-翌年2月,节肢动物群落特征指标与降雨量成正相关关系,7、8月份月均降雨量大于164.5 mm,群落特征与降雨量表现为负相关性。综合分析表明,气象因子对节肢动物群落特征的影响较大,而温、湿度及降雨量的测量和分析较为方便,研究气象因子与节肢动物群落特征的关系,对了解节肢动物群落特征变化规律和主要害虫种群数量的发生规律具有实际意义。     

血培养标本中病原菌的分布特征、耐药性变迁和耐药基因分型

目的 分析嘉兴市中医医院血培养标本中病原菌的分布特征、耐药性变迁和耐药基因分型。方法 将本院2013年1月至2016年12月送检的血培养标本进行培养、转种、分离鉴定和药敏试验,采用聚合酶链反应（PCR）技术进行产超广谱β-内酰胺酶（ESBLs）革兰阴性菌和革兰阳性菌的耐药基因检测,并对阳性菌株、科室分布、耐药性等相关数据进行分析。结果 2013年1月至2016年12月共送检血培养标本27 003份,共分离出病原菌（剔除重复菌株）978株,阳性率为3.62%,2015‒2016年阳性率显著低于2013‒2014年,差异有统计学意义（P<0.01）。血培养阳性株数前三位为ICU、儿科和肾内科,2015‒2016年与2013‒2014年相比,ICU的阳性株数构成比显著下降,儿科、呼吸内科和其他科室显著上升,差异有统计学意义（P<0.01）。血培养致病菌检出率最高的为大肠埃希菌,占18.51%,其次为表皮葡萄球菌,占10.53%,不可忽视的是真菌,占4.91%。2015‒2016年与2013‒2014年相比,金黄色葡萄球菌检出率显著上升,粪肠球菌和近平滑假丝酵母菌的检出率显著下降,差异有统计学意义（P<0.05）。血培养分离的大肠埃希菌对氨苄西林的耐药率最高,肺炎克雷伯菌对呋喃妥因的耐药率最高。2015‒2016年与2013‒2014年相比,大肠埃希菌对氨苄西林/舒巴坦和庆大霉素的耐药率显著下降（P<0.01）,肺炎克雷伯菌对庆大霉素的耐药率显著上升（P<0.01）。分离的表皮葡萄球菌和金黄色葡萄球菌对青霉素的耐药率最高,2015‒2016年与2013‒2014年相比,表皮葡萄球菌对红霉素和氯洁霉素的耐药率显著下降（P<0.01）,金黄色葡萄球菌对环丙沙星和左氧氟沙星的耐药率显著下降（P<0.01）。大肠埃希菌ESBLs（+）菌株对氨苄西林、氨苄西林/舒巴坦、头孢唑啉等的耐药率以及所有基因型表达率均显著高于ESBLs（‒）菌株（P<0.05或P<0.01）;肺炎克雷伯菌ESBLs（+）菌株对头孢唑啉、头孢曲松、庆大霉素等的耐药率以及TEM、SHV、CTX-MⅡ基因型表达率均显著高于ESBLs（‒）菌株（P<0.05或P<0.01）。表皮葡萄球菌检出mecA基因（+）72株,金黄色葡萄球菌检出mecA基因（+）53株。屎肠球菌和粪肠球菌分离株中,未发现有vanA（+）、vanB（+）和vanM（+）万古霉素耐药株。结论 了解本院血培养致病菌整体变化趋势、病区分布特点及耐药性变迁和耐药基因分型,对临床合理使用抗生素和院内感染的控制有重要意义。     

云南六库桔小实蝇成虫种群数量变动及其影响因子分析

应用诱蝇谜引诱剂诱捕法于2003-2005年调查了云南六库桔小实蝇成虫种群动态,系统分析了气候因子及寄主植物对该种群变动的影响。研究结果表明：云南六库桔小实蝇种群发生呈季节性,仅出现于3-12月,成虫消长基本为单峰型,高峰出现在7月。六库桔小实蝇种群数量与气温、降雨量和月雨日数等气象因子有密切关系。决定系数和通径分析结果显示,月降雨量是影响六库桔小实蝇种群动态的主要决策因素;月平均气温和月平均最低气温是影响种群数量变动的主要限制因素,其中,月平均最低温度是间接影响种群数量变动的重要指标。主成分分析筛选出低温条件主成分,其累积方差贡献率达77.65%。逐步回归分析也证实,影响六库桔小实蝇种群月变动的主要气象因子是月平均气温和月平均最低气温。综合分析认为,低温是导致六库桔小实蝇季节性发生的关键因素。     

西藏林芝大气有机氮沉降

2005～2007年,利用雨量器在西藏林芝地区定点采集雨样,研究了该地区降雨中有机氮浓度、沉降量的月、季动态变化.结果表明:西藏林芝地区雨水有机氮月均浓度和沉降量分别为0.21 mg/L和0.50 kg/hm2.不同月份比较,监测期内,2006年7、8月份有机氮浓度平均为1.26 mg/L,明显高于其它年份同时期水平.2007年各月有机氮浓度在0.15～0.53 mg/L之间,变化幅度较小.不同季节内,有机氮浓度差异不大,春\,夏季较高,浓度变化受降雨量影响较小.有机氮湿沉降量与降雨量呈线性正相关,3a的相关系数分别为0.46(p=0.019)、0.69(p=0.001)、0.77(p=0.001).各月沉降量差异较大,2006年6、7两个月有机氮输入量明显偏高,月均达到1.32 kg/hm2,2007年有机氮沉降主要集中在6、7、9月份3个月.四季有机氮沉降量与降雨量呈线性正相关,相关系数0.99(p=0.01).四季中,夏季沉降量最高,为0.93 kg/hm2,占全年的46%.在整个监测期内,有机氮占雨水总氮的比例平均为62%,是大气氮沉降的重要组分.     

北美CHIHUAHUAN荒漠啮齿动物群落动态Ⅱ．季节性和周期性

本文利用时间序列分析方法和季节性指标,讨论了北美Ｃｈｉｈｕａｈｕａｎ荒漠由４科１０属１７种啮齿动物组成的群落的物种数、单位面积个体数与生物量、物种多样性的Ｓｈａｎｎｏｎ与Ｓｉｍｐｓｏｎ指数和均匀性等６个变量的季节变动、季节性和周期性。结果表明：（１）每个季节都有变量达到最大值,但除个体数和均匀性外,其余４个变量均在冬季达到最小值;（２）物种数与生物量及两个物种多样性指数之间,以及两个物种多样性指数相互之间有类似的季节变动规律;（３）除个体数外,群落数量动态的其他变量与８个物种种群的密度存在着显著的负相关关系;（４）物种数有最明显的季节性,季节性指标ＳＩ＝０．６２８;（５）物种数、个体数和生物量在９２个月的研究期中未显示出任何周期性。最后总结了该啮齿动物群落动态的时间模式,提出组成物种种群的扩散和休眠行为是形成这些模式的主要原因。     

Seasonality of retinal detachment incidence and its associations with climate: an 11-year nationwide population-based study

This study aimed to examine the seasonal variability of retinal detachment (RD) in Taiwan by using an 11-yr nationwide population database. This study also investigated the association of weather conditions, i.e., ambient temperature, relative humidity, rainfall, monthly hours of sunshine, and atmospheric pressure, with RD. Data were retrospectively collected from the Taiwan National Health Insurance Research Database. The study sample included 23 718 RD hospitalizations between January 1999 and December 2009. The incidence rate of RD/100 000 people over the 132 months was computed according to sex and age groupings of <20, 20-39, 40-59, and ≥60 yrs. Then, the association between climatic factors and the monthly RD incidence rate was examined. The ARIMA (autoregressive integrated moving average) method was also employed to test the seasonality of RD incidence rates and their association with climatic factors. The annual RD incidence rates were between 7.8 and 10.8 cases/100 000 people during the study period. A fairly similar seasonal pattern of monthly RD incidence rates was apparent for males and females and males and females combined. Rates were highest August through October, decreasing in November, and lowest in February. After adjusting for time, trend, and month, the ARIMA regression models for the male, female, and males and females combined consistently revealed the monthly RD incidence rate was significantly and positively associated with ambient temperature, but negatively associated with atmospheric pressure. The authors conclude that the monthly RD incidence rates were significantly associated with seasonality. The monthly RD incidence rates were positively associated with ambient temperature and negatively associated with atmospheric pressure.     

Seasonality of Retinal Detachment Incidence and Its Associations With Climate: An 11-Year Nationwide Population-Based Study

This study aimed to examine the seasonal variability of retinal detachment (RD) in Taiwan by using an 11-yr nationwide population database. This study also investigated the association of weather conditions, i.e., ambient temperature, relative humidity, rainfall, monthly hours of sunshine, and atmospheric pressure, with RD. Data were retrospectively collected from the Taiwan National Health Insurance Research Database. The study sample included 23 718 RD hospitalizations between January 1999 and December 2009. The incidence rate of RD/100 000 people over the 132 months was computed according to sex and age groupings of <20, 20–39, 40–59, and ≥60 yrs. Then, the association between climatic factors and the monthly RD incidence rate was examined. The ARIMA (autoregressive integrated moving average) method was also employed to test the seasonality of RD incidence rates and their association with climatic factors. The annual RD incidence rates were between 7.8 and 10.8 cases/100 000 people during the study period. A fairly similar seasonal pattern of monthly RD incidence rates was apparent for males and females and males and females combined. Rates were highest August through October, decreasing in November, and lowest in February. After adjusting for time, trend, and month, the ARIMA regression models for the male, female, and males and females combined consistently revealed the monthly RD incidence rate was significantly and positively associated with ambient temperature, but negatively associated with atmospheric pressure. The authors conclude that the monthly RD incidence rates were significantly associated with seasonality. The monthly RD incidence rates were positively associated with ambient temperature and negatively associated with atmospheric pressure. (Author correspondence: henry11111@tmu.edu.tw)     

Geographic dynamics of viral encephalitis in Thailand

Viral encephalitis (VE) continues to be a major disease in Asia, causing serious illness which may result in death or have neurological sequelae. This study involves an ecological analysis of the climatic, geographic and seasonal patterns of clinically reported VE in Thailand from 1993 to 1998 to investigate regional and seasonal differences in disease incidence. Three thousand eight hundred and twenty nine cases of VE were clinically diagnosed nationwide during the study period by the Thai Ministry of Public Health. Spearman rank correlations of temporal, spatial and geographic variables with disease incidence were performed. The monthly incidence of VE correlated significantly with seasonal changes in temperature, relative humidity and rainfall in the north-northeast region of Thailand (P < 0.001), whereas incidence in the south-central region correlated only with relative humidity (P = 0.003). Spatial analysis revealed a positive correlation of disease with elevation (P < 0.001), and negative correlations with rice-field cover (P < 0.001), agricultural land-use (P < 0.001) and temperature (P = 0.004) in the north-northeast region. No significant spatial correlation was identified in the south-central region. The spatial distribution of VE suggests that etiologic variations may be responsible, in part, for the geographic patterns of disease. Active etiologic surveillance is necessary in a variety of geographic settings in order to provide physicians with information necessary for disease prevention and clinical management.     

Visceral leishmaniasis in Muzaffarpur district, Bihar, India from 1990 to 2008

Background

Visceral Leishmaniasis (VL) is a vector-borne disease transmitted by Phlebotomus argentipes. To understand the VL seasonality, annual and monthly variations of VL incidence and its relationship to meteorological variables, the numbers of VL cases reported in Muzaffarpur district, Bihar, India from 1990 to 2008 were studied.

Methods

Annual VL incidence per 10,000 and the total number of annual VL cases reported at block Community Health Centres (CHC), Public Hospitals or Non-Governmental Organisations (NGO) and the number of VL cases per month from 2000 to 2008 as well as the monthly average of cases for 2000–08, 2000–04 and 2005–08 periods along with the monthly averages of temperature, rainfall and relative humidity were plotted. VL Standardised Incidence Ratios per block were computed for the periods of 1990–1993, 1994–1998, 1999–2004 and 2005–2008 and month wise from 2002 to 2008. A negative binomial regression model was used to evaluate the association between meteorological variables and the number of VL cases per month from 2000 to 2008.

Results

A total of 68,358 VL cases were reported in Muzaffarpur district from 1990 to 2008, ranging from 1,2481 in 1992 to 1,161 in 2001. The blocks with the highest number of cases shifted from East (1990–98) to West (1999–2008). Monthly averages of cases ranged from 149 to 309, highest peak in March–April and another one in July. Monthly VL incidence was associated positively to rainfall and negatively to relative humidity and the numbers of VL cases in the previous month.

Interpretation

The number of cases reported to the public health sector allowed the describing of the spatial distribution and temporal variations in the Muzaffarpur from 1990 to 2008. However, to assess the actual VL burden, as well as the efficacy of the control measures applied in the district, reporting from private practices and NGOs should be encouraged.     

Population dynamics of Bactrocera dorsalis (Diptera: Tephritidae) and analysis of factors influencing populations in Baoshanba, Yunnan, China

Population dynamics of the Oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), were monitored year‐round using methyl eugenol‐baited traps in 2003, 2004, 2005 and 2006 in Baoshanba, Yunnan Province, China. Environmental factors including air temperature, rainfall and host‐plant species were analyzed with respect to the population dynamics. This species occurred only during April–November, with one yearly peak in August. The population fluctuation patterns with respect to season were identical in all study years. Correlation analysis and stepwise regression analysis indicated that air temperature, rainfall, sunlight hours and relative humidity were the major climatic factors that correlated with changes in the size of the fly population, and that monthly mean temperature, monthly sunlight hours and monthly relative humidity were most important. The seasonal increase in population size coincided with the fruiting period of the fly's host plants, but host fruit availability influenced the population size only when temperatures were sufficiently high. Cold temperatures may explain why there was no trap capture in the winter months. We believe that air temperature is the key factor explaining the seasonal occurrence of the fly population at Baoshanba.     

雄貉睾丸宽度和血清睾酮水平的季节性变化及其与某些繁殖特性的关系

作者测定并分析了43只雄貉睾丸宽度、血清睾酮水平的季节性变化。结果表明:睾丸宽度和血清睾酮水平呈明显的年周期季节性变化(p<0.01)。秋分(9月)时,睾丸宽度开始增大(p<0.05 );血清睾酮水平在10月开始升高(p<0.05)。各月雄貉的平均睾酮水平与平均睾丸宽度是极显著的正相关(r=0.83,p<0.01 n=11)。雄貉繁殖季节初期,血清睾酮水平与其首、末次的交配日期呈显著负相关(r=-0.525和r=-0.476,p<0.05,n=19)。     

白背飞虱灯下虫量与气象要素关系的相关分析

研究白背飞虱Sogatellafurcifera(Horvath)灯下虫量与气象要素之间的关系。相关分析表明(1)白背飞虱灯下虫量与平均气温、最高气温、最低气温和相对湿度的最优曲线估计为Logistic曲线,其中与3个温度要素之间的相关达到极显著水平,与相对湿度的相关关系达到显著水平;(2)灯下诱虫量与降水量、日照时数、温雨系数和晴雨系数的最优曲线估计为幂函数曲线,除日照时数达到显著水平外,其余3个要素均达到极显著水平;(3)对白背飞虱灯下虫量变化影响较大的因子依次为温雨系数、降水量、日照时数和晴雨系数,相应的偏相关系数分别为0.3908,-0.3727,-0.2996和-0.2268;(4)虫量与相对湿度、平均气温、最低气温和最高气温的偏相关系数分别为-0.1229,0.1152,-0.0410和-0.0106,不相关概率为20.5%~91.3%,远未达到5%的显著水平;(5)通过分析,建立白背飞虱灯下虫量预报方程,为及时进行白背飞虱大田防治提供依据。     

Transmission of urinary schistosomiasis in Sukumaland, Tanzania. 1. Snail infection rates and incidence of infection in school children

Seasonal density fluctuations of Bulinus nasutus populations with accompanying Schistosoma haematobium infection rates in relation to rainfall and habitat water volumes were studied at Ukiriguru, Mwanza, Tanzania. Alongside the snail investigations, 50 school children initially negative for urinary schistosomiasis were examined regularly to determine seasonal incidence rates for the infection. Of the 17,646 B. nasutus collected in 2 years, 156 (0.88%) were found shedding cercariae. Snail populations fluctuated seasonally as influenced by rainfall through its effects on habitat water volume. Monthly snail infection rates ranged from 0.09% to 3.19% and were highest in February and March, at the time of the short dry period. Monthly incidence of S. haematobium in school children ranged between 2.6% and 12.5%, being highest in April and May. There was a significant linear association between monthly snail infection rates and S. haematobium incidence rates in school children (r2s = 0.65 in 1982/83; r2s = 0.87 in 1983/84) suggesting that the maximum transmission period for urinary schistosomiasis in the area occurs during the short dry period, sometime in February/March so that most of the infections in the community would be detected in April/May.     

太湖地区氮素湿沉降动态及生态学意义：以常熟生态站为例

在常熟生态站2001年6月至2003年5月连续两年定位收集湿沉降,对太湖地区氮素湿沉降动态进行研究．结果表明,湿沉降氮输入量季节变化显著,夏、春季高,秋、冬季低．在湿沉降输入氮中NH4^+-N、NO3^--N和DON的比例分别为47．6％、35．1％和17．4％．湿沉降中NH4^+-N主要来自当地农田的氨挥发,湿沉降NH4^+-N月输入量随月降雨量增加而增加(R0=0．3178^**)．该地区空气中NO3^--N浓度相对比较稳定,湿沉降中NO3^--N浓度与降雨量呈负相关(R^2=0．4205^***)．湿沉降NO33^--N月输入量与月降雨次数呈直线正相关(R^2=0．6757***),而与月降雨量相关性较差(R^2=0．1985^*)．湿沉降TN年输入量为27．0kg·hm^-2,并在所有降雨中,氮浓度均超过水体富营养化阈值(0．2mg·L^-1)．     

Reproductive seasonality of fishes from a lotic stretch of the Grande River, high Paraná river basin, Brazil.

We searched for correlations between water level, rainfall, temperature, and reproductive activity of fishes in a lotic stretch of the Grande River below the Volta Grande Dam. Gillnets were used to catch the fish on six field journeys made bimonthly between April 1998 and February 1999. Fish gonads were classified according to maturation grade and the amount of mature or spent gonads was correlated with rainfall and air temperature. Most fish species showed seasonal reproduction (between October and February). The relative frequency of fully mature and spent gonads significantly correlated with rainfall (Spearman r = 0.94, p = 0.005) and air temperature (r = 0.84, p = 0.036), showing the importance of these factors in regulating the reproductive cycle of fishes in this location. Nevertheless, dam operation resulted in minimal water level variation that did not significantly correlate with reproductive activity (r = -0.43, p = 0.396).