Sperm storage in females of the smooth newt (Triturus v. vulgaris L.): I. Ultrastructure of the spermathecae during the breeding season

Sperm storage in cloacal spermathecae was studied in females of Triturus v. vulgaris collected early in the breeding season in southern England. Females collected in terrestrial situations, presumably unmated, were mated in the laboratory, and the ultrastructure of the transferred sperm and the spermathecae was observed at various intervals after mating. Sperm from a spermatophore cap lodged in a female's cloacal orifice can migrate into spermathecae within 1 hr after mating. Spherical structures on the axial fibers of some sperm in the cap could indicate immaturity. Disorderly clusters of sperm from the cap are still present in the cloacal chamber 12 hr after mating but are absent 24 hr after mating. During storage, sperm often are in tangled masses in the spermathecal tubules. The sperm are coated with spermathecal secretions, and some sperm nuclei were observed embedded in the spermathecal epithelium. Little evidence for spermiophagy early in the breeding season was found. During oviposition, mazes of sperm occur external to the spermathecal orifices, and sperm may be released in this condition onto eggs as they pass through the cloaca. The tangled clusters in which sperm are found from pick-up to oviposition are hypothesized as an adaptation to reduce the effectiveness of sperm competition from the ejaculates of rival males. Additional studies, using the same protocol and covering the entire cycle of sperm storage, are necessary to enable interspecific comparisons leading to phylogenetic hypotheses.     

C-Map: A High-level Language for Engineering Analysis and Design

C-MAP is a high level language for engineering computations. In addition to the conventional programming features, C-MAP has over 100 functions covering a broad spectrum of numerical methods for engineering computations ranging from elementary calculus to non-linear constrained optimization problems. These basic functions can be nested in innumerable ways that give C-MAP great flexibility and power. C-MAP comprises four integrated components: (i) a fullscreen text editor with multiple stacked windows for simultaneous editing of programs and output files; (ii) a simplified C-like programming language with control structures, recursive functions, math library, and built-in functions for advanced engineering computations including the processing of general matrix and complex expressions; (iii) an interactive expression processor; and (iv) a simple authoring system with automatic cross-referencing of keywords. The program's versatility helps to meet the different needs of users at different stages of learning. A beginner may use only the built-in functions for math and matrix operations to get immediate, useful results; the advanced users may write their own functions for more complex problems. This paper discusses the features of C-MAP and its applications in teaching structural engineering     

关于环保建筑材料的使用和可持续发展的探讨

随着环保型消费逐步占据主流,住宅建筑的生产商和消费者都对建材提出了安全、健康、环保的要求。采用清洁卫生技术生产,减少对天然资源和能源的使用,大量使用无公害、无污染、无放射性环保型建筑材料,有利于环境保护和人体健康,是住宅建筑发展的必然趋势。     

On the (Un)Reliability of TCP Connections: The Return of the End-to-End Argument

This paper discusses the dangers of relying solely on TCP reliability when implementing dependable computing systems, even when those systems are designed to work over a LAN environment. The discussion includes a real-life example from our recent experiences in developing such a system.     

深井破碎围岩条件下煤巷锚杆构件合理配套

基于徐州矿区张小楼井24302工作面运输平巷的地质条件，在深井破碎围岩条件下进行了煤巷锚杆支护试验，介绍了锚网带索支护技术参数和不同构件配合支护的巷道矿压显现．根据顶板锚杆螺母撕裂和穿过托板与钢带导致的锚杆支护失效问题，在实验室完成了锚杆、托板、钢带和螺母等支护构件配合的力学性能试验．试验表明：直径20mm的螺纹钢锚杆杆体性能稳定，破断载荷均在186kN，杆体和螺母的螺纹配合完好，顶圆底四方螺母能与托板和钢带很好地配合，外接圆直径为38mm的六方螺母与托板和钢带不能很好地配合．深井高应力破碎围岩条件对锚杆支护系统中的锚杆、锚固剂、托板、钢带和螺母等构件的力学性能配合要求高，它们的力学性能应基于锚杆的破断力合理配套．     

控制辐照肉脂肪氧化技术的研究

通过对辐照剂量、贮藏温度、氧气含量和抗氧化剂等影响脂肪氧化因素的研究,揭示了辐照肉脂肪氧化的机理。结果表明:辐照处理可以明显诱导肉的脂肪氧化反应;降低贮藏温度、减少包装中的氧气含量和添加抗氧化剂,对抑制辐照肉的脂肪氧化效果明显。     

电子自旋共振波谱法检测含骨类食品的初步研究

电子自旋共振(Electron spin resonance,ESR)波谱测定是检测含骨类食品自由基的有效方法之一.本工作研究了辐照诱导的含骨类食品的ESR波谱特征、样品制备方法及辐射剂量-效应关系.结果表明,辐照前后ESR波谱图形、g因子和△H皆有明显差异,据此很容易区分辐照与未辐照含骨类食品样品;冷冻干燥和磨碎是样品制备过程中的关键步骤;吸收剂量(0.3-10.1kGy)与ESR信号强度有良好的线性关系;ESR信号的相对强度还与动物种类有关.这为制定我国含骨类辐照食品的ESR检测方法标准提供了依据.