肌肉自发振动过程中结合几率与化学反应速率的变化

定量分析肌球蛋白与肌动蛋白丝的结合几率及相关化学反应的速率常数,对于准确掌握肌肉收缩的内在机制具有非常重要的意义.以肌肉自发振动的实验结果为依据,从振动过程所满足的动力学方程出发,推导出结合几率与肌丝滑行速度及肌节长度之间的定量关系,并求得化学反应速率随肌肉收缩的速度变化而改变的数学规律.结果显示,结合几率的基准值由溶液中主要化学成分的浓度决定;结合几率的变化值与肌肉收缩的速度成正比,与肌节长度成反比;而化学反应速率随收缩速度按指数规律变化.上述结果与实验值基本一致.     

Breeding biology of Mountain Plovers ( Charadrius montanus ) in the Uinta Basin

The known Mountain Plover population breeding on the Myton Bench, Duchesne County, Utah, is small, composed roughly of 30 adults and young after each breeding season. Currently, its location is peripheral to the species main range. This shrub-steppe breeding habitat differs from the shortgrass prairie habitat with which this bird is historically associated. Between 1996 and 1998 we made observations at nesting sites located consistently in 2 concentrated areas surrounded by large tracts of similar habitat. Activity may be focused in these specific areas because of breeding-site fidelity; this behavior is common among most shorebirds and has been documented for the Mountain Plover in Colorado. Also, Mountain Plovers are social and tend to choose nest sites near others. Most nests in Utah were located within close proximity of mounds of white-tailed prairie dogs ( Cynomys leucurus ), and all were situated near roadways or oil well pads. Mountain Plovers were often observed with broods on these bare areas at night. We conclude that Mountain Plovers on the Myton Bench are distributed in clumped breeding colonies within large areas of apparently favorable habitat.     

Use of interstate highway overpasses and billboards for nesting by the common raven ( Corvus corax )

Common ravens are usually rather shy birds around their nests and avoid nesting too near human activity. We here report the use of overpasses along heavily traveled Interstate Highway 84 in Idaho and Utah for nest placement. Nests are within 6 m of passing vehicles.     

Habitat use and subspecific status of Merlins, Falco columbarius , wintering in central Utah

Most ornithological literature for Utah reports the status of the Merlin ( Falco columbarius ) as rare or scarce. Only the most recently published checklists (Behle and Perry 1975, Behle et al. 1985) record it as uncommon. Likewise, a 1998 printed checklist (Utah Ornithological Society 1998) list it as uncommon. Also misrepresented in the literature are the status and distribution of the 3 rather distinct subspecies, each of which occupies dissimilar habitats during the breeding season. We made random observations of Merlins in northern Utah beginning in the 1950s and then studied them continuously between 1992 and 1997 in Utah County, Utah. During the 1992-1997 period, we were able to clearly allocate 95 males and 76 females to subspecies, including within our count 58 falcons trapped (some fitted with radio telemetry). The winter habitat in which they occurred was categorized as either urban (mainly dense residential area) or rural (agricultural lands, dairy farms, or scattered homes). There was a statistically significant ( X 2 F. c. columbarius frequenting urban areas 68% of the time, and prairie parkland-breeding F. c. richardsonii frequenting rural habitats 78% of the time.     

摩托车曲柄花键冷挤刀具的设计

北方易初为了提高摩托车曲柄花键的生产率 ,从日本进口了冷挤机床及其冷挤刀具 ,该刀具价格昂贵 ,约为一万美元。该厂在近一年的国内调研中 ,还未找到能生产该刀具的厂家。本文就针对北方易初的摩托车曲柄花键 ,应用弹、塑性理论 ,有限元方法等来研究冷挤过程中的材料流动情况 ,塑性变形及弹性恢复 ,由此来确定刀具的齿数及每齿的形状尺寸等相关参数 ,设计并画出冷挤刀具的零件图。为能自行制造该类刀具提供有益的参考。     

直觉模糊集所诱导的软集语义及其三支决策

借助于阴影集,利用直觉模糊参数,将直觉模糊集转化为悲观阴影集和乐观阴影集,提出直觉模糊集悲观三支决策和乐观三支决策,给出直觉模糊集诱导软集的方法。利用三支决策理论,提出软集三支决策定性模型。结合直觉模糊集悲观三支决策和乐观三支决策,利用直觉模糊参数,给出软集三支决策定量模型。     

Sm(Ⅲ)(BCB)3与DNA的相互作用机理

以中性红(NR)作探针,利用光谱法研究钐(Ⅲ)与灿烂甲酚蓝(BCB)形成的配合物Sm(Ⅲ)(BCB)3与鲱鱼精脱氧核糖核酸(DNA)的相互作用.研究结果表明Sm(Ⅲ)(BCB)3与鲱鱼精DNA结合比n(Sm(Ⅲ)(BCB)3)n(DNA)=41,其结合常数为2.30×105L/mol.Sm(Ⅲ)(BCB)3与鲱鱼精DNA之间的作用方式主要为沟槽作用方式,△rH☉m和△rS☉m都有利于Sm(Ⅲ)(BCB)3-DNA超分子复合物的形成,但主要影响因素是△rS☉m.     

Gonadotropin-releasing hormone analogue binds to luteal cells and inhibits progesterone production.

Although gonadotropin-releasing hormone (GnRH) is believed to mediate the hypothalamic control of pituitary gonadotropin secretion, continuous or repeated administration of GnRH or its agonist analogues has been shown to cause paradoxical antifertility effects in several species, including primates. GnRH-induced interruption of reproductive cycles and pregnancy is associated with diminished progesterone production, implying defective function of the corpus luteum. These luteolytic effects have been attributed to the well recognized desensitising actions of elevated luteinising hormone (LH) levels on ovarian LH receptors and steroidogenesis, subsequent to GnRH-induced gonadotropin release from the anterior pituitary. However, treatment with high doses of exogenous LH did not cause suppression of serum progesterone levels during early pregnancy in rats, whereas a highly active GnRH analogue was effective in this regard. These observations suggested that GnRH and its agonist analogues, given in high or sustained doses, can exert a direct action on the ovary that is independent of the pituitary. This hypothesis was further supported by the ability of GnRH and its agonists to inhibit human chorionic gonadotropin (HCG)-induced ovarian and uterine weight gain in hypophysectomised rats and to delay the onset of puberty in intact female rats. Also, GnRH and its agonist analogues have recently been shown to inhibit steroidogenesis induced by follicle-stimulating hormone (FSH) in cultured granulosa cells, confirming the direct action of such peptides on the ovarian follicle. The marked inhibitory effects of GnRH and its agonists on corpus luteum function suggest that these compounds could exert direct actions by binding to specific receptors on luteal cells. The present experiments, which examine the effects of GnRH agonists on luteal steroidogenesis, demonstrate the existence of such actions and their mediation by specific high-affinity receptor sites present in luteal cell membranes.     

Association scan of 14,500 nonsynonymous SNPs in four diseases identifies autoimmunity variants

We have genotyped 14,436 nonsynonymous SNPs (nsSNPs) and 897 major histocompatibility complex (MHC) tag SNPs from 1,000 independent cases of ankylosing spondylitis (AS), autoimmune thyroid disease (AITD), multiple sclerosis (MS) and breast cancer (BC). Comparing these data against a common control dataset derived from 1,500 randomly selected healthy British individuals, we report initial association and independent replication in a North American sample of two new loci related to ankylosing spondylitis, ARTS1 and IL23R, and confirmation of the previously reported association of AITD with TSHR and FCRL3. These findings, enabled in part by increased statistical power resulting from the expansion of the control reference group to include individuals from the other disease groups, highlight notable new possibilities for autoimmune regulation and suggest that IL23R may be a common susceptibility factor for the major 'seronegative' diseases.