黑龙江省乌裕尔河流域丹顶鹤等珍稀涉禽航空调查报告

利用Y-11型单翼轻型飞机,航高100米,航速140公里/小时,采用且测全区调查方法,对黑龙江省乌裕尔河流域丹顶鹤等涉禽进行了航空调查,续航里程2184公里,调查面积共计为209,000公顷。结果发现调查区内有丹顶鹤(Orus japoncnsis)173只,白枕鹤(Grus vipio)19只,白鹤(Grus leucogeraous)24只,白鹳(Ciconia ciconia)19只等。     

Muscle contraction: a new interpretation of the transient behaviour of muscle

Piazzesi et al. [G. Piazzesi, L. Lucii, V. Lombardi, J. Physiol. 545 (2002) 145–151] made a study on the muscle transients due to step changes in force using improved time resolution and recorded filament movement and shortening velocities in the four phases. They point to Phase 2 and to Phase 4 (working muscle) and claim that their results do not contradict the swinging-cross-bridge (SCB) model which has a much-quoted constant power stroke of about 150 Å (their value of 70 Å was smaller). Siding with the SCB model, they nevertheless record that the power stroke decreases with load. We are pleased with this experimental result as it conforms to our theory, published in 1996, of an impulsive model with a much smaller step-size distance z (≈20 Å). Using their data we obtain precise interval times and estimates of filament movement in Phase 2 and in working muscle. Our first result is that the time frames (interval times) for Phase 2 are the same as in working muscle. Moreover, we demonstrate that the authors’ data verify the correctness of our calculated z values. There are eight active ATP events in Phase 2 in time frame t compared to one in working muscle in the same time frame t. This gives, for the first time, precise numbers for contractile events. We show that the SCB model is incorrect and our analysis supports the impulsive model with a much smaller filament (zero-load) motion, ≈20 Å per ATP split.     

勺嘴鹬在中国的分布状况和面临的主要威胁

勺嘴鹬(Calidris pygmaea)是全球极危鸟类,估计其种群数量为360~600只。根据近年来的野外调查和历史资料查阅,勺嘴鹬在中国沿海各省级行政区域均有分布。本文介绍了勺嘴鹬在中国的种群数量和分布。其中江苏省的东台市和如东县的滩涂湿地是目前已知的勺嘴鹬全球数量最大的迁徙停歇地。东台市滩涂单次调查记录的勺嘴鹬最大数量为144只,如东县滩涂单次调查记录的勺嘴鹬最大数量为103只。广东省雷州半岛的滩涂和福建省闽江口的滩涂为勺嘴鹬在中国最大的两个越冬地。滩涂栖息地的丧失和退化、非法捕猎、环境污染以及人类活动干扰是勺嘴鹬面临的主要威胁。为了更好地保护勺嘴鹬,我们建议加强对勺嘴鹬关键栖息地的保护与管理,加强对滩涂湿地保护的宣传教育,加强对中国沿海勺嘴鹬的调查研究以及同其他国家地区的交流合作。     

Chromosome counts inPosidonia (Posidoniaceae)

The five species ofPosidonia occuring in Western Australia all have a diploid chromosome number of 20.     

Optimum proportions selected with unequal sex numbers

Summary Optimum proportions selected for each sex, giving the maximum selection response up to some specified time, have been investigated. Selection was carried out from a constant number of individuals scored per generation. It has been shown that the maximum response after t generations of selection is obtained when the number of individuals scored and the proportion selected is the same for males and females every generation. Specific situations, where the sex-ratio among scored or breeding individuals or the selected proportion of males or females is taken as given throughout the whole selection process, have been studied, optimum strategies being described in each case. The procedures leading to maximum advance at the selection limit have also been considered in all these situations.