Escalation of a coevolutionary arms race through host rejection of brood parasitic young

Cuckoo nestlings that evict all other young from the nest soon after hatching impose a high reproductive cost on their hosts. In defence, hosts have coevolved strategies to prevent brood parasitism. Puzzlingly, they do not extend beyond the egg stage. Thus, hosts adept at recognizing foreign eggs remain vulnerable to exploitation by cuckoo nestlings. Here we show that the breach of host egg defences by cuckoos creates a new stage in the coevolutionary cycle. We found that defences used during the egg-laying period by host superb fairy-wrens (Malurus cyaneus) are easily evaded by the Horsfield's bronze-cuckoo (Chrysococcyx basalis), a specialist fairy-wren brood parasite. However, although hosts never deserted their own broods, they later abandoned 40% of nests containing a lone Horsfield's bronze-cuckoo nestling, and 100% of nests with a lone shining bronze-cuckoo nestling (Chrysococcyx lucidus), an occasional fairy-wren brood parasite. Our experiments demonstrate that host discrimination against evictor-cuckoo nestlings is possible, and suggest that it has selected for the evolution of nestling mimicry in bronze-cuckoos.     

棕头雀鹛育雏巢穴及其栖息地调查报告

2012年1月—11月,采用实地调查、录音、录像、固定样线的方法进行棕头雀鹛分类、育雏、栖息地研究。首次发现了15只6♀9♂繁殖期的棕头雀鹛,证明长青自然保护区有一个比较稳定的棕头雀鹛繁殖种群。结果表明:棕头雀鹛分布海拔区间1 050～2 200 m;四种林型、四种植被类型内有分布;坡中部3只,下部10只,上部2只。棕头雀鹛一夫一妻制,每巢都是四只幼雏;雏鸟属于晚成鸟;巢穴位于坡脚,营灌木空中巢穴,向阳、巴山木竹稠密。巢材为竹叶、树叶、草茎。幼雏食物鳞翅目昆虫、水生虫子、螳螂、蚱蜢等。     

驻涡燃烧室内涡系分布研究

为清晰了解驻涡燃烧室内流场的涡系分布,对中心驻体为67%燃烧室当量宽度的驻涡燃烧室流场,在驻涡腔无喷射和有喷射两种状况下分别进行冷态数值模拟,详细研究流场内旋涡分布情况.结果表明:流道前部存在4个影响很小、沿流动方向运动、分布于驻体与端壁角区的螺旋状旋涡;流道后部存在1个由2个旋涡构成、面积较大的回流区;流道中部的驻涡区旋涡情况复杂,在驻涡腔无喷射情况下,主流与驻涡区之间悬挂驻留2个稳定的驻涡,驻涡腔内存在不稳定且数目不确定的旋涡;当驻涡腔前驻体有喷射存在时,驻涡腔内形成4个均匀且稳定的旋涡.     

针刺对青少年运动员长跑中血糖的调节作用

采用平衡重复测试法,对16名男子耐力长跑运动员在间隔期不少于7d内,在测定前一个月对实验组的6名运动员实行每晚一次和实验前一次双侧“三阴交”、“关元”、“安眠”、“内关”、“三里”针刺,而对照组的10名运动员不做任何处理,2h后,受试者在运动场400m跑道上进行21km的长跑能力测试．前5km中,受试者以中等速度跑步。探讨了针刺长跑运动员相关穴位对长跑能力的影响,要求16名运动员同时跑完,而其后的16km则可随意选择速度以最短时间完成．结果显示：与对照组相比。所有实验组运动员跑步时间明显缩短．显示跑步全程中,实验组运动员的血糖水平较高。血清胰岛素的水平较低．对照组运动员两小时的血糖、血清胰岛素在运动过程中与实验组相比均无显著差异．表明在运动前对长跑运动员实施针灸相关穴位能更有效地提高长跑运动的能力．     

CsCl和CsBr中自陷态激子的研究

在单电子Ｈａｒｔｒｅｅ－Ｆｏｃｋ近似的基础上采用扩展离子方法研究了ＣｓＣｌ型晶体中自陷态激子（ＳＴＥ）的结构，研究表明ＣｓＣｌ中三重态ＳＴＥ的位形是较强的ｏｆｆ－ｃｅｎｔｅｒ，ＣｓＢｒ中三重态ＳＴＥ的位形是较弱的ｏｆｆ－ｃｅｎｔｅｒ，ＣｓＢｒ中单重态ＳＴＥ的位形是ｏｎ－ｃｅｎｔｅｒ。对ＳＴＥ及Ｆ心的发光研究结果与实验符合较好。     

专性厌氧菌发酵罐制氢工艺

采用批式发酵工艺研究了专性厌氧菌P的产氢特性.分别探讨了P菌在小样及发酵罐扩大试验中的生长周期、pH值、葡萄糖浓度以及糖蜜浓度等生态因子对产氢能力的影响.结果表明,P菌是一种高效产氢的菌株,在培养10h后进入对数生长期和高速产氢阶段.当葡萄糖浓度为10 g/L,初始pH为7.0,接种比例为10％时,小样发酵和发酵罐的气体总产量均达到最大值,分别为485 mL和17.4L;在发酵罐中,通过连续补加NaOH溶液使pH恒定在7.0左右,可使每升培养基产氢量达到2.473 L,比小样提高了5％,此时葡萄糖分解率达到95.2％,且氢气的质量分数达到68.73％;利用糖蜜作为发酵底物,具有广阔的经济效益和除废产能的环境效益,当糖蜜底物浓度为35 g/L时的产气能力最佳,发酵罐中最大产气量为22 L.     

A brood parasitic catfish of mouthbrooding cichlid fishes in Lake Tanganyika

Brood parasitism, where a brood of the parasitic species is fostered by the parents of another species, is well known among birds. In most cases, such offspring show a complete reliance upon their host parents for food, protection and warmth until their independence. In other vertebrate groups, however, such total dependence upon a host species is unknown. I report here the first example of true brood parasitic behaviour discovered among fishes. In Lake Tanganyika, an endemic mochokid catfish, Synodontis multipunctatus Boulenger, is a brood parasite of mouthbrooding fishes of the family Cichlidae. The eggs of the catfish are incubated in the mouths of any of several host species together with the host's eggs, but hatch earlier. Following absorption of their yolk sacs, the catfish fry feed upon the fry of the host while still in its mouth. Thus the early stages of development of this catfish not only depend upon their hosts for food and protection, but exploit almost their entire parental investment.     

高原断续训练对中长跑运动员生化指标的影响

本文通过对青海师范大学15名高水平中长跑运动员在高原一高原断续训练期间训练前、后血液变化情况，来观察高原——高原断续训练对红细胞、血红蛋白、红细胞压积、白细胞的影响．     

可编程逻辑器件(PLD)的竞争冒险现象研究

介绍了可编程逻辑器件（PLD）的特点，讨论了使用PLD进行逻辑电路设计的过程中可能出现的竞争冒险现象，分析了产生竞争冒险的原因，提出了消除竞争冒险的一些方法。     

重型汽车转向双摇臂机构的优化设计

转向双摇臂机构的运动协调性直接影响双前桥重型汽车的行驶性能,因此对其转向双摇臂机构的优化设计具有重要意义。文章介绍了重型汽车转向双摇臂机构的转向原理,用空间几何方法建立了双摇臂机构优化设计的数学模型,并用MATLAB软件优化工具箱中的优化计算函数来编制程序,对双摇臂机构参数进行了优化,使转向双摇臂机构的性能得到显著提高。     

The alignment of molecular cloud magnetic fields with the spiral arms in M33

The formation of molecular clouds, which serve as stellar nurseries in galaxies, is poorly understood. A class of cloud formation models suggests that a large-scale galactic magnetic field is irrelevant at the scale of individual clouds, because the turbulence and rotation of a cloud may randomize the orientation of its magnetic field. Alternatively, galactic fields could be strong enough to impose their direction upon individual clouds, thereby regulating cloud accumulation and fragmentation, and affecting the rate and efficiency of star formation. Our location in the disk of the Galaxy makes an assessment of the situation difficult. Here we report observations of the magnetic field orientation of six giant molecular cloud complexes in the nearby, almost face-on, galaxy M33. The fields are aligned with the spiral arms, suggesting that the large-scale field in M33 anchors the clouds.     

The genome of the protist parasite Entamoeba histolytica

Entamoeba histolytica is an intestinal parasite and the causative agent of amoebiasis, which is a significant source of morbidity and mortality in developing countries. Here we present the genome of E. histolytica, which reveals a variety of metabolic adaptations shared with two other amitochondrial protist pathogens: Giardia lamblia and Trichomonas vaginalis. These adaptations include reduction or elimination of most mitochondrial metabolic pathways and the use of oxidative stress enzymes generally associated with anaerobic prokaryotes. Phylogenomic analysis identifies evidence for lateral gene transfer of bacterial genes into the E. histolytica genome, the effects of which centre on expanding aspects of E. histolytica's metabolic repertoire. The presence of these genes and the potential for novel metabolic pathways in E. histolytica may allow for the development of new chemotherapeutic agents. The genome encodes a large number of novel receptor kinases and contains expansions of a variety of gene families, including those associated with virulence. Additional genome features include an abundance of tandemly repeated transfer-RNA-containing arrays, which may have a structural function in the genome. Analysis of the genome provides new insights into the workings and genome evolution of a major human pathogen.     

Observation of individual vortices trapped along columnar defects in high-temperature superconductors

Many superconductors do not entirely expel magnetic flux-rather, magnetic flux can penetrate the superconducting state in the form of vortices. Moving vortices create resistance, so they must be 'pinned' to permit dissipationless current flow. This is a particularly important issue for the high-transition-temperature superconductors, in which the vortices move very easily. Irradiation of superconducting samples by heavy ions produces columnar defects, which are considered to be the optimal pinning traps when the orientation of the column coincides with that of the vortex line. Although columnar defect pinning has been investigated using macroscopic techniques, it has hitherto been impossible to resolve individual vortices intersecting with individual defects. Here we achieve the resolution required to image vortex lines and columnar defects in Bi2Sr2CaCu2O8+delta (Bi-2212) thin films, using a 1-MV field-emission electron microscope. For our thin films, we find that the vortex lines at higher temperatures are trapped and oriented along tilted columnar defects, irrespective of the orientation of the applied magnetic field. At lower temperatures, however, vortex penetration always takes place perpendicular to the film plane, suggesting that intrinsic 'background' pinning in the material now dominates.     

对现代教学媒体在高校武术专业教学运用中的若干思考

采用文献资料法、实践法等研究方法,分析现代教学媒体在高校武术专业教学中的作用及优势,并探讨其运用过程中所存在的问题;旨在优化高校武术教学手段与方法,进而提高教学质量和丰富教学内容.