Accounting for unknown foster dams in the genetic evaluation of embryo transfer progeny

Animals born by embryo transfer (ET) are usually not included in the genetic evaluation of beef cattle for preweaning growth if the recipient dam is unknown. This is primarily to avoid potential bias in the estimation of the unknown age of dam. We present a method that allows including records of calves with unknown age of dam. Assumptions are as follows: (i) foster cows belong to the same breed being evaluated, (ii) there is no correlation between the breeding value (BV) of the calf and the maternal BV of the recipient cow, and (iii) cows of all ages are used as recipients. We examine the issue of bias for the fixed level of unknown age of dam (AOD) and propose an estimator of the effect based on classical measurement error theory (MEM) and a Bayesian approach. Using stochastic simulation under random mating or selection, the MEM estimating equations were compared with BLUP in two situations as follows: (i) full information (FI); (ii) missing AOD information on some dams. Predictions of breeding value (PBV) from the FI situation had the smallest empirical average bias followed by PBV obtained without taking measurement error into account. In turn, MEM displayed the highest bias, although the differences were small. On the other hand, MEM showed the smallest MSEP, for either random mating or selection, followed by FI, whereas ignoring measurement error produced the largest MSEP. As a consequence from the smallest MSEP with a relatively small bias, empirical accuracies of PBV were larger for MEM than those for full information, which in turn showed larger accuracies than the situation ignoring measurement error. It is concluded that MEM equations are a useful alternative for analysing weaning weight data when recipient cows are unknown, as it mitigates the effects of bias in AOD by decreasing MSEP.     

Effect of habitat fragmentation on spawning migration of brown trout (Salmo trutta L.)

Abstract –  Human-induced habitat alteration is one of the main causes of the decline of freshwater fish populations. The watershed of the River Bidasoa (Spain) is an example of heavily fragmented habitat. The local brown trout ( Salmo trutta L.) population is disturbed, with evidence of poor recruitment as well as low adult densities in the main stem. Forty male and female adult migratory trout were tagged with external or internal radio transmitters and released. Fixed stations with data loggers and mobile antennae were used with daily surveys to track fish movements during the migration and spawning period (3 months). Migration distances did not exceed 10 km, and half of the fish never entered a tributary in the study area. Fragmentation because of weirs on the main stem apparently prevented fish from reaching their spawning destination. Fish that entered the tributaries were first confronted with an accessibility problem because of low discharge. However, each fish chose one tributary, without making attempts to run up in other tributaries. Once in the tributary, fish were restrained in their upstream movements by dams. The study area appeared to be isolated from the vast upper part of the watershed. Within the study area, upper parts of tributaries also seemed strongly disconnected from the main stem. This study illustrates the negative impact of river fragmentation on S. trutta migration pattern. Population sustainability can be directly affected through the low availability of spawning grounds for migratory fish. Long-term effects of fragmentation may cause reproductive isolation within watersheds, which in the case of trout also means isolated phenotypic population units.     

连江鱼类资源现状调查及资源衰退原因分析

于2005～2006年间对清远市筑坝后连江的鱼类种群结构状况进行了调查。在河流的上游、中游、下游三个江段采样,共采集到鱼类87种,分属于7目18科69属,优势种为亚科(占鲤科总数的29.4%)、鲌亚科(占鲤科总数的15.7%)鱼类。通过与历史资料比较发现,多种适应急流的鱼类、洄游或半洄游性鱼类和产飘浮性卵鱼类已在连江中上游消失,连江鱼类组成、结构和分布已发生了较大的变化。     

黄丘区小流域暴雨径流动力特征对淤地坝配置的响应

为定量揭示淤地坝措施配置对黄丘区小流域暴雨径流形成及演进过程的影响,采用室内小流域人工模拟降雨试验,对不同淤地坝措施布设情景下（无坝、单坝、双坝）小流域不同断面径流的水动力、侵蚀动力特征进行研究。结果表明：径流量与含沙量整体均随时间推移而增大,无淤地坝布设情景下径流量增幅为114.60 cm3/s,双坝情景的径流量增幅仅有70.11 cm3/s;淤地坝对小流域暴雨径流演进过程的影响显著,淤地坝布设后径流流态由主要的紊流-缓流变为以层流-缓流为主,雷诺数Re减小幅度达到12.04%～85.85%;动力参数中径流功率ω和雷诺数Re可以被认为是能够较好描述不同淤地坝布设下侵蚀产沙的动力因子。研究结果对于揭示流域暴雨径流过程及成灾机理具有重要现实意义,可为科学评价水土保持措施调控径流过程的效应提供理论依据。     

小型震损水库溃坝风险分析研究

为研究小型震损水库溃坝风险,对水库的溃坝路径、溃坝概率、溃坝后果进行分析,建立风险评价模型,最终确定其风险指数。在简单介绍此模型的基础上,通过实例说明其在水库风险分析中的应用,确定模型的实用性及便捷性。     

白山金矿尾矿库坝体材料基本物理性试验研究

本研究通过风干含水率、尾矿粉和白灰配比、比重、颗粒大小分析、液塑限等试验对白山金矿尾矿库坝体材料基本物理性试验进行分析。结果表明,尾矿粉和白灰混合比为100:0.1;尾矿粉的基本物理力学性指标与一般低液限粘土相近。     

病险水库除险加固方案决策研究

【目的】针对当前病险水库大坝除险加固方案优选理论方法的缺失和不足,提出基于区间数GRA决策与AHP-Entropy主客观综合赋权的除险加固方案决策方法。【方法】考虑决策信息的模糊不确定性,采用区间数表达决策信息,结合GRA决策方法,求解各备选方案对理想最优方案与临界最优方案的灰色关联系数,通过建立最优化模型得出考虑理想最优与临界最优方案的综合关联系数;综合AHP主观赋权与Entropy客观赋权方法对各属性指标进行赋权,对主客观权重建立相对熵最小化优化模型,得出主客观综合权重,进而求解各指标的加权综合关联度,以此对各备选方案进行排序决策,并通过实际算例验证决策方法的合理性。【结果】建立了基于区间数GRA决策和AHP-Entropy主客观综合赋权的病险水库除险加固方案的灰色关联度优选决策方法。实例计算表明,该方法有效地解决了病险水库除险加固方案优选中属性值为区间数的灰色多属性决策及AHP-Entropy主客观综合赋权问题。【结论】所构建的基于区间数GRA与AHP-Entropy主客观综合赋权的除险加固方案决策方法具有一定的合理性,为水库大坝除险加固方案决策提供了一条有效途径。     

不同频率洪水遭遇下溃坝洪水演进的二维模拟

【目的】建立适合黑河下游地区的溃坝洪水演进的二维数学模型,为该水库的安全运行和调洪决策提供参考。【方法】根据天然河道复杂而不规则的地形特点,以及溃坝洪水的传播和运动特性,建立适合黑河下游地区高程跨度很大的溃坝洪水演进的二维数学模型;利用非结构化三角形网格,采用单元中心的有限体积法求解控制溃坝水流运动的二维方程;应用所建模型,对黑河金盆水库10 000年一遇入库洪水漫顶所致溃坝洪水(即工况1)进行数值模拟,分析不同时刻的水深分布图、流速矢量图以及淹没范围的变化过程;在此基础上,探讨100年一遇入库洪水延时遭遇10 000年一遇入库洪水工况(即工况2)下溃坝洪水的演进变化过程,分析该工况下淹没水深的变化范围。【结果】工况1、工况2下大坝溃决时间分别为该工况模拟初始时间后的15.6,37.5h,工况1、工况2下5个沿程观测点的最大淹没水深分别为3.10~6.18m和3.66~6.91m,最大流速分别为2.28~8.68m/s和2.46~9.40m/s。【结论】所建立的溃坝洪水二维模型可以模拟流域不同时刻的水深及流速分布,计算结果具体到点,为洪水风险分析和灾害损失评估提供了依据。     

黑龙江省林口县保安水库大坝安全评价浅论

介绍保安水库工程概况，并依据工程质量评价和实际运行情况对其防洪标准进行分析、复核，最后得出综合评价结果。可供业内人员参考。     

林口县跃进水库大坝安全评价工作浅谈

大多数的病险水库,在每年汛期都成为各地方防汛的重点,都要花费大量的人力、财力进行抢险。近几年来国家为保证人民的生命、财产安全,加大了对病险水库的资金投入,怎样才能对病险水库进行准确的安全评价,成为近年来水利行业的工作重点之一。