Pheromone-based female mate choice and its effect on reproductive investment in a spitting spider

Numerous studies have focused on whether organisms can signal or perceive pheromones and use chemical signals in species and mate recognition. Recently, there have been an increasing number of studies investigating whether pheromones are used in mate choice. Yet, little attention has been paid in exploring the effects of pheromone-based mate choice on reproductive investment. We first tested this hypothesis by providing virgin Scytodes sp. females with a choice between two virgin males in the presence of chemical signals alone and found strong evidence of an odor-based mate preference. We then examined the consequences of the odor-based mate choice by allowing female Scytodes sp. that had previously made an odor-only mate choice to mate with preferred and non-preferred males, respectively. We measured the success of copulation, mortality of male, pre-oviposition interval, egg-sac weight, egg weight, fecundity, fertility, embryonic period, and size of offspring at hatching. Females that mated with the preferred males produced significantly heavier egg sacs that contained more and larger eggs with a greater fertility. Significantly more non-preferred males than preferred males were killed by spitting. However, pre-oviposition interval, embryonic period, and hatchling size were not affected by female mate choice. This study is the first to demonstrate that female spiders are able to regulate their highly valuable reproductive investment based solely on chemical signals.     

Experimental study of recirculating flows generated by lateral shock waves in very large channels

Due to the lack of data on hydraulic-jump dynamics in very large channels, the present paper describes the main characteristics of the velocity field and turbulence in a large rectangular channel with a width of 4 m. Although a hydraulic jump is always treated as a wave that is transversal to the channel wall, in the case of this study it has a trapezoidal front shape, first starting from a point at the sidewalls and then developing downstream in an oblique manner, finally giving rise to a trapezoidal shape. The oblique wave front may be regarded as a lateral shockwave that arises from a perturbation at a certain point of the lateral wall and travels obliquely toward the centreline of the channel. The experimental work was carried out at the Coastal Engineering Laboratory of the Water Engineering and Chemistry Department of the Technical University of Bari (Italy). In addition to the hydraulic jump formation, a large recirculating flow zone starts to develop from the separating point of the lateral shock wave and a separate boundary layer occurs. Intensive measurements of the streamwise and spanwise flow velocity components along one-half width of the channel were taken using a bidimensional Acoustic Doppler Velocimeter (ADV). The water surface elevation was obtained by means of an ultrasonic profiler. Velocity vectors, transversal velocity profiles, turbulence intensities and Reynolds shear stresses were all investigated. The experimental results of the separated boundary layer were compared with numerical predictions and related work presented in literature and showed good agreement. The transversal velocity profiles indicated the presence of adverse pressure gradient zones and the law of the wall appears to govern the region around the separated boundary layer.     

过去20年气候变暖对我国冬季采暖气候条件与能源需求的影响

20世纪80年代中期以来,我国气候变暖,尤其是90年代中期以来的显著变暖,对我国冬季采暖气候条件和能源需求产生了很大影响。论文以全国458个气象台站逐日平均气温为基础,对其影响进行了分析。依照《采暖通风与空气调节设计规范G(B50019-2003)》的规定,确定了采暖初(终)日及集中(过渡)采暖期的划分方法,并采用度日法分析了采暖强度。结果发现与1980年以前时段相比,1985-2004年以及1995-2004年间,我国集中采暖区和过渡采暖区的界线明显北移,尤其110E°以东地区北移最大达2～3个纬距;北方大部地区采暖期长度缩短5～15d,长江以南地区缩短最大达30d以上;北方采暖强度普遍减小200℃以上;理论上由气候变暖导致的我国北方地区冬季采暖耗能降低了5%～30%,长江中下游地区冬季采暖耗能降低了30%以上。     

Seasonal variation in dissolved gaseous mercury and total mercury concentrations in Juam Reservoir, Korea

Dissolved gaseous mercury (DGM) and total mercury (TM) concentrations were measured in Juam Reservoir, Korea. DGM concentrations were higher in spring (64+/-13pgL(-1)) and summer (109+/-15pgL(-1)), and lower in fall (20+/-2pgL(-1)) and winter (23+/-6pgL(-1)). In contrast, TM concentrations were higher in fall (3.2+/-0.1ngL(-1)) and winter (3.3+/-0.1ngL(-1)) than in spring (2.3+/-0.1ngL(-1)) and summer (2.2+/-0.4ngL(-1)). DGM concentrations were correlated with water temperature (p<0.0001), ORP (p<0.0001), UV intensity (UV-A: p=0.008; UV-B: p=0.003), and DOC concentration (p=0.0107). DGM concentrations varied diurnally with UV intensity. The average summer DGM (109+/-15pgL(-1)) and TM (2.2+/-0.4ngL(-1)) concentrations in Juam Reservoir were higher than the averages for North American lakes (DGM=38+/-16pgL(-1); TM=1.0+/-1.2ngL(-1)), but lower than levels reported for Baihua Reservoir in China.     

高烈度地震区隧道软硬围岩交接段刚柔并济抗减震技术研究

为提高高烈度地震区隧道抗震性能,以某铁路隧道为研究背景,分析3种抗减震措施下隧道不同监测点隧道拱顶沉降、边墙收敛、衬砌结构PGA及最小安全系数,通过对比分析得到最优抗减震措施.结果表明:相比于工况1,工况2隧道拱顶沉降减小10.54％ ～81.10％,边墙收敛减小13.92％ ～78.77％,衬砌结构PGA减小31.4...     

历山山地草甸的物种多样性及其与土壤理化性质的关系

运用12种多样性指数综合分析了历山舜王坪草甸的物种多样性．随着放牧强度渐弱，物种多样性升高，土壤环境因子影响多样性指数，且有机质、N和K对各多样性指数的影响都较大．各群落多样性指数有大体一致的变化趋势，且其随Cu,K含量的增加而增加，说明土壤养分的增加有利于物种多样性的升高；而有机质和N增加群落多样性反而减少，这是因为人为干扰的影响超过了土壤环境因子的影响．综合以上分析得出，该研究地物种多样性指数的影响因子有放牧强度和土壤环境因子等，其中放牧的影响是最主要的．图3表3参15     

中国工业SO2排放量动态变化分析

中国工业SO2减排工作的重点。经济增长、经济空间结构变化、技术进步是影响污染物排放量变化的三个重要因素。在分析我国工业SO2排放量、排放结构、排放强度等变化趋势的基础上,通过构建对数平均权重分解模型定量分解经济增长、结构变化、技术进步这3个因素对工业SO2排放量变化的贡献。结果表明：（1）中国工业SO2排放量年均增长48.7×10^4 t,年均增长率为3.2%,且2002—2006年增速加快;（2）分地区看,1991年以来,东部地区SO2排放量所占比重明显下降,中部地区略有上升,而西部地区所占比重增加显著;（3）单位产值工业SO2排放强度在研究期内迅速降低,年均下降幅度为8.4%,对减缓SO2排放量的过快增长起到了积极作用;（4）经济增长平均每年促进SO2排放量增长183.7×10^4 t,技术进步则平均每年使SO2排放量减少134.2×10^4 t,空间结构因素平均每年减少SO2排放量0.8×10^4 t。可以看出,长期以来,虽然我国的技术水平有了一定程度提高,但经济规模的扩张使中国工业SO2排放量持续增长,对中国环境压力形成了巨大压力,同时,经济总量在不同地区的分配对SO2排放量的影响也在不断变化中。     

耕种方式对稻田甲烷排放的影响

通过田间试验研究了稻田2种土壤耕作强度(深翻耕和浅旋耕)和3种水稻栽培方式(直播、抛秧和插秧)下的CH4排放规律,以探讨稻田土壤耕作强度和水稻栽培方式对CH4排放的影响。结果表明,各水稻栽培方式下,深翻耕和浅旋耕稻田CH4排放季节变化趋势一致。土壤耕作强度对稻田CH4季节排放总量的影响受水稻栽培方式的制约:抛秧方式下,浅旋耕与深翻耕处理相比,稻田CH4排放量减少31.37%(P0.05);而直播和插秧方式下,2者CH4季节排放总量相当。水稻栽培方式显著影响稻田CH4排放季节变化规律:直播稻田CH4排放大致呈现"双峰型"模式,且水稻生育前期CH4排放水平较低;而移栽稻田(抛秧和插秧)CH4排放大致呈现"三峰型"模式,且水稻生育前期CH4排放水平较高。与深翻耕抛秧相比,深翻耕直播和深翻耕插秧稻田CH4排放分别减少23.31%和42.51%;而浅旋耕方式下,3种水稻栽培处理CH4季节排放总量相当。降低土壤耕作强度,以浅旋耕代替深翻耕,可以减少耕作对土壤的扰动,在一定程度上减少稻田CH4排放。与水稻移栽相比,水稻直播能够显著降低水稻生育前期CH4排放,具有一定的CH4减排潜力,但仍需加强中后期田间水分管理。     

吉林省生态足迹时间序列计算与分析

为了定量评价吉林省可持续发展程度的动态变化及其影响因素,计算了1994-2003年吉林省生态足迹时间序列,着重分析了该省生态足迹、生态盈亏和生态足迹强度的动态变化及其驱动机制。结果显示：吉林省生态足迹和生态承载力的人均水平和总量均呈增长趋势,自然资源供需结构渐趋多元化;自然资源供需的非均衡增长导致生态赤字的出现和持续增长,表明目前吉林省的发展模式是不可持续的;自然资源利用效益不断提高,但仍低于全国和东部地区的平均水平。最后,根据生态盈亏的影响因素提出了降低和消除生态赤字的措施。     

粉喷桩体的力学性质试验研究

粉喷桩是处理软弱地基的一种重要方法.通过水泥土的室内配合比试验,研究了粉喷桩体的抗拉、抗压和抗剪强度性质及其影响因素,可为粉喷桩施工和设计提供理论指导.图1,表3,参5.