Secular Trends of Reproductive Indices in Chuvashian Women

In the present cross-sectional study of the Chuvashian rural population, we examined the secular trends of age at menarche, the age at menopause, the reproductive period, and the age of the first marriage of Chuvashian women. The cohort included 745 women aged 18–90 years; age at menarche (N = 653) ranging from 10 to 24 years (mean 15.42 ± 2.11). Data regarding menopausal age was obtained from 316 women born between 1920 and 1950 (mean 48.5 ± 4.6). Statistical analyses included the maximum likelihood estimation and a Whiskers plot. Women born during the second through the fourth decade of the 20th century showed increasing mean values of age at menarche from 15.4 (second decade) up to 16.5 (fourth decade) and after that a decrease of the mean values to 14.0 (ninth decade). The mean values of menopausal age increased from 47.0 (women born from 1920 to 1925) to 49.3 (born from 1945 to 1950). Age at first marriage showed a trend of decreasing age. Our study demonstrated secular trends of age at menarche in Chuvashian women who had matured after World War II and also confirmed secular trends of increased age at menopause and the duration of the reproductive period. Women, whose maturation was during or immediately after World War II, showed a higher age at menarche and a higher dispersion of age at menopause.     

Annual cycle and inter-annual variability of gross primary production and ecosystem respiration in a floodprone river during a 15-year period

1. Temporal variation in ecosystem metabolism over a 15‐year period (1986–2000) was evaluated in a seventh order channelised gravel bed river (mean annual discharge 48.7 m³ s^?1) of the Swiss Plateau. The river is subject to frequent disturbance by bed‐moving spates. Daily integrals of gross primary production (GPP) and ecosystem respiration (ER) were calculated based on single‐station diel oxygen curves. 2. Seasonal decomposition of the time series of monthly metabolism rates showed that approximately 50% of the variation of GPP and ER can be attributed to season. Annual GPP averaged 5.0 ± 0.6 g O₂ m^?2 day^?1 and showed no long‐term trend. 3. Ecosystem respiration, averaging 6.2 ± 1.4 g O₂ m^?2 day^?1, declined from 8.8 to 4.1 g O₂ m^?2 day^?1 during the 15‐year period. This significant trend paralleled a decline in nitrate and soluble reactive phosphorus concentrations, and the biochemical oxygen demand discharged by sewage treatment facilities upstream of the study reach. The ratio of GPP to ER (P/R) increased from 0.53 to about 1 as consequence of ER reduction. 4. Bed moving spates reduced GPP by 49% and ER by 19%. Postspate recovery of GPP was rapid between spring and autumn and slow during winter. Recovery of ER lacked any seasonal pattern. Annual patterns of daily GPP and to a minor extent of daily ER can be described as a sequence of recovery periods frequently truncated by spates. 5. The study showed that disturbance by frequent bed‐moving spates resulted in major stochastic variation in GPP and ER but annual patterns were still characterised by a distinct seasonal cycle. It also became evident that stream metabolism is a suitable method to assess effects of gradual changes in water quality.     

A Review of the Genera Croconema Cobb, 1920 and Pseudochromadora Daday, 1899 (Nematoda, Desmodoroidea): New Species from the Coasts of Kenya and Australia

This article is a review of the subfamily Desmodorinae (Nematoda, Desmodoroidea) and two related genera within this subfamily, Croconema Cobb, 1920 and Pseudochromadora Daday, 1899 with keys to genus or species level, genus diagnoses and lists of valid species. An emended diagnosis of, and discussion on, Sibayinema Swart & Heyns, 1991, is presented. Three new species are described: Croconema floriani sp.n. from the coast of Kenya, Pseudochromadora galeata sp.n. and P. securis sp.n. from the coast of Australia.     

李肖叶甲成虫数量及三维空间格局动态

对合肥地区李肖叶甲成虫数量动态及三维空间格局进行研究,结果表明该成虫5月下旬初见,6月4日至7月16日为发生高峰期,9月上旬仍有零星虫口。6月4日至9月10日种群增长模型为y=1692.2258e-0.0545t,6月4日至8月27日树冠上部部位增长模型为y=205.60e-0.0523t,树冠西部部位的增长模型为y=257.13e-0.0505t。样地中的李肖叶甲5月21日至8月13日半变异函数方程是y=0.0709x3-10.479x2+391.67x-300.71、y=-0.0122x3+1.1201x2-19.781x+317.84、y=-0.0013x3+0.1613x2-4.4862x+67.363、y=-0.0016x3+0.9177x2-11.495x+551.94、y=-0.0029x3+0.3034x2-7.5906x+103.37和y=-0.0002x3+0.0172x2-0.4975x+13.691,变程在20.3938—65.0289之间,均为聚集格局,聚集强度指标表明也均为聚集格局;树冠东、西、南、北方位的水平分布5月21日至8月13日的C值均大于1,I值均大于0,CA值均大于0,Iw值均大于1,为聚集格局;树冠上、中、下方位的垂直分布6月4日至8月13日的C值均大于1,I值均大于0,CA值均大于0,Iw值均大于1,为聚集格局;5月21日至8月13日的树冠东、南、西、北、上、中、下部位的C值均大于1,I值均大于0,CA值均大于0,Iw值均大于1,三维分布均为聚集格局。用Iwao公式计算的结果与聚集强度指标分析的结果一致。6月4日—8月13日林间李肖叶甲的种群聚集均数λ值均大于2,聚集是李肖叶甲本身的行为所致。     

Partition of the genetic trend to validate multiple selection decisions

In this note, a procedure to partition the genetic trend of a selected population is presented. Each part of the genetic gain accounts for the Mendelian sampling terms of different groups of animals, which can be sometimes assigned to different selection policies. The method is based on a simple transformation of the predicted breeding values. The procedure was illustrated with two simulated examples. In the first example, the genetic trend is partitioned into two pieces, one coming from the selection on sires and the other coming from the selection on dams. The second example shows how the impact of an artificial insemination center in the genetic gain of the whole population can be evaluated.     

微生物污垢检测技术的特点、现状与发展趋势

微生物污垢是工业冷却水污垢的重要组成部分.在适宜条件下,引起污垢的微生物迅速繁殖.不但会显著增大污垢热阻、流动阻力和腐蚀速率,甚至还会堵塞流道而引发停机故障.本文介绍了微生物污垢的概念,阐述了微生物污垢检测技术研究的地位、作用和特点,归纳了目前已知的微生物污垢的形成过程及其主要影响因素,着重分析了目前国内外应用较广的微生物污垢检测方法、优缺点及其最新研究动态.展望了微生物污垢检测技术未来的发展趋势.     

土壤质量与可持续土地利用管理

可持续发展的基础是农业的可持续发展,可持续农业应当包含对于资源的成功管理来满足人类需求的变化,同时维持或提高环境质量,保护自然资源。土壤质量是可持续土地利用管理的重要指标,本文在深入剖析土壤质量与可持续土地利用管理内涵基础上,总结、分析了土壤质量和可持续土地利用管理的相互关系,提出了二者研究的发展趋势。并就土壤质量研究如何在可持续土地利用管理中发挥重要作用,以及目前存在的问题等做了探讨。     

我国植被数量分析方法的研究概况和发展趋势

植被数量分析是现代植被研究的重要手段,数量分类和排序是现代植被生态学研究最重要的,也是应用最广泛的生态学技术。数量分析方法在20世纪50年代引入植被生态学研究领域,我国学者在70年代后期开始研究植被的数量分类和排序。本文主要从相关资料、应用研究、新方法研究三个方面论述了我国植被数量分析方法的发展,重点阐述了从20世纪70年代后期以来出现的并且被广泛应用的新方法及其应用研究概况,并在此基础上分析了植被数量分析方法未来的发展趋势。     

Plant species loss in an urban area (Turnhout, Belgium) from 1880 to 1999 and its environmental determinants

Information from four archival literature sources from the late 19^th century was matched to present-day plant species distribution data for the region of Turnhout (Belgium) and for 15 smaller sub-regions within this region. In the entire study area 25% of the species recorded in the late 19^th century went extinct during the 20^th century and the extinction rate doubled at the more detailed sub-region level. Binary survival-extinction data and continuous residuals from a linear regression between historical and present-day abundance categories were used to investigate underlying ecological factors of change including habitat preference, ecological amplitude and life strategy. Species increasing relative to the overall trend were generally correlated with nutrient-rich habitats while declining species were more associated with nutrient-poor situations. Generalist species have become relatively more common whilst habitat specialists have strongly declined, resulting in a flora with many ‘losers’ and a few tolerant ‘winners’. The winners are often competitive species while the losers are mainly stress-tolerating species and species with combined life strategies (e.g. SC, SR). Correlations between the decline of historically present habitats and extinction rates of related habitat specialist species show clear trends. We suggest the most important factors involved in changes in flora diversity and vegetation composition are habitat loss due to urbanization and habitat deterioration, mainly due to agricultural intensification.     

使用粪堆数量估计日本奄美群岛上琉球兔的种群数量

为了测量奄美岛上濒危物种琉球兔 (Pentalagusfurnessi)的丰盛度 ,我们计数了森林中道路、溪流和森林地被物中的粪堆数量。计算用的模型包括新粪堆的数量及其年龄、总粪堆数量、每天产生的平均粪堆数 ,以及在森林地被物和溪边的粪堆数量的回归方程。估计在 1 993- 1 994年期间该岛上有 2 5 0 0 - 6 1 0 0只琉球兔 ,在 2 0 0 2 - 2 0 0 3年间有 2 0 0 0 - 4 80 0只。通过比较粪便丰盛度和在森林道路旁观察到的琉球兔数量 ,我们考察了该模型的有效性 ,最后将以前调查的数据应用于该模型以确定种群下降的程度