建筑结构的主动隔震控制

建筑结构的主动控制和被动控制可以有效地减少地震荷载时结构的动力反应。被动隔震控制已被广泛应用于实际的结构控制。为了进一步降低结构震动,主动控制无疑是一种比较理想的方法,它对于提高结构抵抗外界激励不确定性的能力,直接减少输入的干扰,以及在震动发生时连续自动的调整结构动力特性方面均优于被动控制。通过试验对建筑结构主动隔震控制进行研究,试验在伊利诺伊大学香槟分校的智能实验室进行。试验模型是3层2跨的剪切型结构,设置在底层的3个伺服千斤顶提供不超过2%建筑自重的控制力,控制结构的面内运动(X方向,Y方向和XY平面内的转动)。试验结果表明该控制技术不仅可以有效的控制基础隔震层的位移,而且可以控制基底剪力在5%结构自重以内。     

Biotic and abiotic factors related to redband trout occurrence and abundance in desert and montane streams

Redband trout Oncorhynchus mykiss gairdneri in the Columbia River Basin of western North America occupy desert and montane streams with variable habitat conditions. In general, desert streams are lower in gradient and elevation, contain less large substrate and more silt substrate, are less shaded by overhead vegetation, and have higher summer water temperature than montane streams. Consequently, we assessed whether the relationships between biotic and abiotic factors and the occurrence and abundance of redband trout in southwestern Idaho differed between desert and montane streams (<25 m mean width). Increased occurrence of redband trout in desert streams was most strongly related to increased stream shading and decreased amounts of silt substrate, followed by increased amounts of cobble/boulder substrate and absence of piscivorous fish (i.e., smallmouth bass Micropterus dolomieui and northern pikeminnow Ptychocheilus oregonensis ). In montane streams, increased occurrence of redband trout was most strongly related to decreased site elevation and increases in cobble/boulder substrate, followed by decreases in stream gradient and width. Furthermore, occurrence of redband trout decreased in desert streams at mean summer (June–August) water temperature (Temp smr ) >16 °C, whereas for montane streams, occurrence increased at Temp smr >9 °C. Redband trout density in desert streams was most strongly related to higher stream order (i.e., headwater streams), increased stream shading, and increased amounts of cobble/boulder substrate. In montane streams, redband trout density was not well explained by any stream conditions, but stream shading had the strongest positive relationship with density. Redband trout density was negatively related to Temp smr in desert streams, but the relationship was weak for montane streams. That environmental conditions related to the occurrence and abundance of redband trout differ between desert and montane streams is important for fisheries managers who manage these disparate populations occurring in such close proximity to each other.     

A plasma protein marker for population genetic studies of the desert tortoise ( Xerobates agassizi )

Fifty-seven individual plasma samples from desert tortoises ( Xerobates agassizi ) representing 10 separate populations were analyzed by polyacrylamide gel electrophoresis using alkaline buffers. An albumin-like protein was found to be polymorphic for two electromorphs in northern populations inhabiting the Mohave Desert Province while Sonoran Desert populations to the south were monomorphic. The genetic divergence demonstrated in this survey is similar to earlier studies and provides evidence for the Colorado River as a potential barrier to gene flow among tortoise populations. These data suggest that tortoise plasma, examined by various electrophoretic methods, may provide a nondestructive means of determining the broad regional origin of desert tortoises.     

Feeding habits of metamorphosed Ambystoma tigrinum melanostictum in ponds of high pH (> 9)

During the spring breeding season throughout the channeled scablands of eastern Washington, metamorphosed male and female blotched tiger salamanders ( Ambystoma tigrinum melanostictum ) utilize oropharyngeal suction to capture large quantities of small aquatic invertebrates. Stomach content analysis on salamanders from three populations of this subspecies revealed that they consume the following taxa: Copepoda, Cladocera, Culicidae, Anostraca, and Chironomidae. Although the amount of energy obtained by adults via in-water feeding was not calculated, the large volume of aquatic invertebrate material flushed from salamander stomachs suggests that this feeding strategy should add significantly to their total annual nutrient consumption.     

Use of radio transmitter implants in wild canids

Twelve adult and five juvenile coyotes and 20 adult kit foxes were implanted with radio transmitters using relatively simple surgical procedures. Four foxes were successfully implanted in the field. None of the animals implanted exhibited noticeable behavioral effects, and no deaths were confirmed to result from implantation. Implants were attached to the peritoneum in adult coyotes and kit foxes and were left free - floating within the abdominal cavity of the coyote pups. Both procedures produced satisfactory results. Radio signals transmitted from implants had less range than those from traditional neck collar transmitters. Implants offered benefits unavailable with traditional collar transmitters: no external packaging to influence behavior, ability to radio monitor small or juvenile animals, and ability to acquire various physiological data on free - ranging individuals.         

Reproductive attributes of some Rocky Mountain subalpine herbs in successional context

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 st1\:*{behavior:url(#ieooui) } /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Selected reproductive attributes of herbaceous plant species were compared among three stages of a sere in the subalpine zone of Utah’s Wasatch Mountains: herbaceous meadow, aspen grove, spruce-fir forest. No successional trends in seed size or inferred mode of seed dispersal were detected. We ascribe the deviation of these findings from those of most other studies to differences in climate, life-form composition, or community age between our sere and those of other studies. A variety of flower colors were found in the meadow stage, grading into a predominance of white flowers under conifers. Animal vectors of pollen, capable of effecting plant outcrossing, were most abundant in the meadows and an order of magnitude less abundant under aspen.       

New records of western Trichoptera with notes on their biology

Western records for 27 species of Trichoptera are given; a majority of the records are from the Beartooth Mountains of northwestern Wyoming. In addition, examples of variation in the male genitilia of Limnephilus coloradensis (Banks) are figured and the female is described. Some comments regarding the larvae of Allomyia ( Imania ) are presented.     

Plasticity and polymorphism in seed germination of Mimulus guttatus (Scrophulariaceae)

Normal 0 false false false EN-US X-NONE X-NONE MicrosoftInternetExplorer4 /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Table Normal"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-priority:99; mso-style-qformat:yes; mso-style-parent:""; mso-padding-alt:0in 5.4pt 0in 5.4pt; mso-para-margin:0in; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:11.0pt; font-family:"Calibri","sans-serif"; mso-ascii-font-family:Calibri; mso-ascii-theme-font:minor-latin; mso-fareast-font-family:"Times New Roman"; mso-fareast-theme-font:minor-fareast; mso-hansi-font-family:Calibri; mso-hansi-theme-font:minor-latin; mso-bidi-font-family:"Times New Roman"; mso-bidi-theme-font:minor-bidi;} Seeds of 12 populations of Mimulus guttatus representative of the Wasatch Mountain ecotype were incubated for 17 months (one natural season plus a year) in five artificial climates found in phytotron studies to be important to the growth of the plants of that form of monkey flower. In all but the coldest climate, germination occurred promptly (3–8 days, on average), peaked during the first three weeks, and then tapered off gradually well into the second season. Generally, the amount and timing of germination was plastic, showing much the same range of responses in widely different climates both overall and for individual populations. However, in some cases, there were significant differences between populations indicative of polymorphism within the species. For example, germination was significantly slower, more variable, and less in amount the higher the elevation of origin of the populations. The responses of the population suggest the presence of both much plasticity and much polymorphism for germination characteristics in this form of M. guttatus.     

Terrestrial vertebrates of the Mono Lake islands, California

We compared vertebrate populations between the two major islands (paoha and Negit) in Mono Lake, California and the adjacent mainland to further elucidate the mechanisms underlying island colonization. Deer mice ( Peromyscus maniculatus ) and montane voles ( Microtus montanus ) were captured on Paoha, but only deer mice were captured on Negit. In contrast, eight species of rodents were captured on the mainland. Overall rodent abundance on Paoha and the mainland was similar, but on Negit it was about three times greater than on Paoha or the mainland. Adult deer mice from Paoha were significantly ( P Canis latrans ) and one or two species of lagomorphs were observed on the islands and the mainland. No amphibians or reptiles were found on the islands; both occurred in low numbers on the mainland. Rafting and human transport are probable means of colonization for mice and voles. The occurrence of coyotes on the islands may have modified historic predator-prey relationships, and thus the population of rodents and lagomorphs.