Ultrasonographic examination of the carpal canal in dogs

The aim of this study was to determine the course of the median nerve and its adjacent structures in the carpal canals of 8 healthy dogs by using high-frequency transducers. Before performing ultrasonography, the transverse and posteroanterior diameters as well as the perimeter of the carpus were measured at just proximal to the side of the carpal pad. The anatomical structures were then determined at two levels of the carpal canal, which were named the proximal and distal levels, on the transverse sonograms. The cross-sectional areas, perimeters and the transverse and posteroanterior diameters of the median nerve were measured at these levels. Although all the measurements were larger at the proximal level, significant differences between the proximal and distal levels were determined for the cross-sectional area, the perimeter and the transverse diameter of the median nerve. On the transverse sonogram, the deep digital flexor tendon was seen in almost the center of the carpal canal like a comma shape and also it had a small concavity on the caudal side. The superficial digital flexor tendon was seen as an ovoid shape on the transverse sonograms and it was located nearly at the posterior side of the carpal canal. Both tendons were seen as intermediate-grade echogenic structures. The median artery was located inside of the concavity of the deep digital flexor tendon. Also, the median nerve was seen at the posteromedial side of the median artery. As a result of this study, the cross-sectional areas of the median nerve ranged between 1.01-2.68 mm² at the proximal level and between 0.93-1.91 mm² at the distal level.     

基于SALTMOD模型的灌溉水矿化度对土壤盐分的影响

以河套灌区沙壕渠灌域为例,运用SALTMOD模型探讨了区域尺度灌溉水矿化度对根层土壤盐分的影响。结果表明,根层土壤盐分随灌溉水矿化度的增大而增加,加大排水沟深度和提高渠道衬砌水平可缓解高矿化度灌溉水对土壤积盐的影响;采用地下微咸水和黄河水混合灌溉可有效控制盐渍化的发展,混合比在1∶1范围内时,根层土壤处于脱盐状态,最高脱盐率为23%,脱盐率高于引用黄河水灌溉的脱盐率(4%)。因此,适度利用地下微咸水灌溉,可有效的控制地下水位,节约淡水资源。     

太阳辐射作用下冻结期衬砌渠道温度场分析

【目的】对季节性冻土区衬砌渠道在太阳辐射作用下的温度场进行数值模拟,分析太阳辐射对渠道温度分布的影响。【方法】利用Hottel太阳辐射模型,结合热传导理论和有限元分析方法,考虑渠道自身的遮蔽作用,对太阳辐射作用下的梯形衬砌渠道的温度场进行计算。【结果】提出了梯形渠道太阳辐射的计算方法;衬砌渠道表面太阳辐射的日变化表现为早晚最小、中午最大;渠道阴、阳坡接受到的太阳辐射差异明显,阴坡太阳总辐射约为阳坡的20%;渠道表面温度的日变化趋势与大气温度相同,近似为正弦分布,其温度变幅小于大气温度变幅,变化滞后于太阳辐射约2.5h,阴、阳坡温度最大相差4℃左右,阳坡温度值与日间温度增加速率均大于阴坡。【结论】渠道温度变化与太阳辐射有密切关系,阴、阳坡接受到的太阳辐射量不同是渠道温度存在较大差异的原因,太阳辐射是渠道冻融循环的动力,在渠道冻胀研究中必须考虑太阳辐射的影响。     

绿洲灌区小麦水分生产率在不同尺度上的变化

水分生产率是衡量农业生产水平和农业用水科学性与合理性的综合指标。文章根据民乐县洪水河灌区1995-2006年的气象、灌溉用水量、灌溉面积、作物产量资料,从田间、斗渠、干渠、灌区4个不同尺度分析了小麦灌溉水分生产率年份间的变化情况。结果表明：不同尺度上平均灌溉水分生产率不同,田间尺度为1.414 kg/m3,斗渠尺度为1.013 kg/m3,干渠尺度为1.089 kg/m3,灌区尺度为0.894 kg/m3,并且不同尺度上的灌溉水分生产率在年份间的差异也比较大。2001年洪水河灌区实施了节水灌溉工程,不同尺度上的平均灌溉水分生产率在2001-2006年较1995-2000年有所提高,田间、斗渠、干渠、灌区分别提高了7.9%、19.4%、16.5%、7.4%,说明目前斗渠、干渠尺度上节水力度大,节水效益明显,而灌区尺度还有较大的节水潜力,应成为未来农业节水研究的重点。     

Note on the Taxonomy of Genetta

The recruitment patterns of six teleosts were studied at King’s Beach, Algoa Bay. February to May marked the major recruitment period for Diplodus sargus, Lithognathus mormyrus, Rhabdosargus globiceps and Trachurus capensis. The major recruitment of Sarpa salpa fry took place between August and September. Pomadasys olivaceum fry of < 5 cm total length were caught throughout the year indicating an extended breeding period. The estimated growth rates of new recruits between February and May (autumn/winter) was 0,60 cm month ^-1 for L. mormyrus, 0,75 cm month^-1 for ft globiceps and 0,40 cm month^-1 for T. capensis. The empirical growth curve derived for S. salpa indicated a growth rate of 0,75 cm month^-1. No growth estimates could be made for P. olivaceum or D. sargus.     

季节冻土区刚柔混合衬砌梯形渠道冻胀机理试验

输水渠道冻胀破坏是寒冷地区渠道破坏的主要表现。为了探明刚柔混合衬砌渠道的冻胀机理,分析复合衬砌渠道的冻胀变形规律和冻胀过程中的水分变化规律,以及柔性复合土工膜的变形特征,该研究借助季节冻融条件下刚柔混合衬砌梯形渠道的原型观测成果,分析了刚柔混合衬砌渠道的最低地温变化规律、冻深变化规律和冻胀量与冻胀力的变化规律,重点研究了冻融条件下渠基土壤的水分迁移规律,以及复合土工膜的变形特征和强度变化。结果显示:刚柔混合衬砌渠道的冻胀变形最大值位于渠底和阴坡1/3处,最大冻胀量为11.2和13.1 cm,衬砌结构向上隆起。冻结期,渠基土壤0~60 cm深度范围内含水率随深度增加而增大,60~120 cm深度范围内的含水率随深度增大而逐渐减小。水分迁移最大值发生在渠道底部,迁移率为13.2%。经过一个冻融周期的循环,复合土工膜的强度和变形量仍然保持在90%以上,强度和变形损失值较小,可充分发挥复合土工膜防渗抗冻胀和适应变形的特性。该研究为刚柔混合衬砌渠道的设计、推广应用提供了理论依据。     

侧渠底高对分水口水力特性影响数值模拟研究

目前对灌区分水口水力性能的研究多集中在主渠和侧渠底部高程相等的情况下,对于普遍存在的侧渠底部高程高于主渠时的分流特性缺乏系统研究。该文在试验基础上,利用FLOW-3D软件对侧渠不同底高、主渠来流量的矩形渠道分水口进行了数值模拟研究,将主渠各断面水深、流速的模拟值与实测值进行对比,发现流速变化与实测值变化规律基本一致,相对误差均小于10%,利用FLOW-3D对分水口进行数值计算具有合理可信性。结果表明：分水口处的水面波动受主渠来流的影响,流量越大,波动越大;高于侧渠底高的水流会对低于侧渠底高的下层水流产生影响,使下层水流具有向上的流速分量,参与分水口分流;同一主渠来流量下,随侧渠底高的增加,侧渠进口断面最大流速和水深逐渐减小;侧渠进口断面靠近上游端的区域湍动较大,而在下游端靠近底部湍动能值较小。研究为灌区配水及水量控制提供了参考依据。     

陕西关中灌区支斗渠管理体制改革研究

归纳总结了陕西关中9大灌区,支斗渠管理体制改革的几种主要形式及运作程序,探讨了各改制形式的成效、特点,分析了各自的利弊、存在的问题,并提出了改进意见。这是灌区主动适应社会主义市场经济的发展,增强自我发展活力,促进水利工程经济良性循环的根本之举与必由之路。同时对长期困扰我国各灌区量大面广的田间工程投入和管护问题提出一条解决途径     

湿度、NaCl浓度对铜仁珍珠豆型花生种子活力及发芽的影响

研究发芽床不同含水量及NaCl浓度对铜仁珍珠豆型花生种子活力及发芽的影响,试验表明,发芽床含水量从20%升高至40%,铜仁珍珠豆型花生种子的发芽率、发芽势、发芽指数呈上升趋势,含水量继续升高至60%,三项指标呈下降趋势,40%是铜仁珍珠豆型花生最适发芽床含水量,花生发芽各项指标达到最高。用NaCl溶液处理种子,浓度从0mol/L升高至0.5mol/L,花生种子的发芽率、发芽势、发芽指数三项指标表现出先急剧后缓慢又急剧下降的趋势。     

Heritable characters of the red blood cells of sheep

Extract

From the start I want to make it clear that the research work described here is the work of one of us (J.V.E.), and the reason why I am presenting his work is that Evans comes from New Zealand and presented a paper on this subject to the annual meeting of the British Association for the Advancement of Science last September in Sheffield, so that it seemed appropriate that his work should also be presented to this Society.