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111.
By employing a calibrated and tested computer model, simulations of ceiling heat transfer in typical residential attics located in 12 locations across the United States were obtained to study the sensitivity of attic radiant barrier performance to local climate parameters. For each location, the net ceiling heat flux over the summer cooling season was computed for an attic with and for an attic without an installed radiant barrier. The net reduction of heat flux induced by the radiant barrier was computed and then related to climate variables. Among the local environmental parameters, the local ambient air temperature, local ambient humidity, and latitude had significant effects on the performance of radiant barriers. It was concluded that the installation of radiant barriers would be most beneficial in regions with high outdoor air temperatures and high relative humidity. 相似文献
112.
The effect of stream regulation on the physico-chemical properties of the palmiet river,South Africa
The effect of regulation, by multiple impoundment, on ‘discontinuity’ (recovery) ‘distances’ (sensu Ward and Stanford, 1983) for various physico-chemical attributes of the Palmiet River (a short, steep gradient, cool temperate, acid, low-nutrient system) was investigated. Physico-chemical features were measured monthly, from February 1986 to August 1987, at 11 sites along the river, but concentrating on two zones: one below an upper-reach impoundment, Nuweberg Dam, and one below a middle-reach impoundment, Arieskraal Dam. Median total suspended solids, nitrates, nitrites and ammonium all increased below both dams with varying levels of ‘recovery’. Median spot temperatures, pH and alkalinity increased below Nuweberg, but decreased below Arieskraal Dam, whereas the converse was true for soluble reactive phosphate. Nuweberg had no effect on conductivity and total dissolved solids, while Arieskraal caused a slight decrease. The river remained well oxygenated down its length. Distinct seasonal variations were recorded for: flow rate, with flow reversal below Nuweberg and flow constancy below Arieskraal; temperature, with seasonal shifts and dampening of annual temperature range below both dams; alkalinity, with seasonal shifts below Arieskraal, and nitrites and nitrates, but not for any other attributes. At least partial recovery was noted in all cases, but in some instances, recovery was incomplete to the estuary. The implications of such alterations, for invertebrates, in terms of reduction in habitat diversity as well as for food supply must be considerable and studies are currently under way to determine community structure and diversity. 相似文献
113.
Martin Jack; Slemon Alan G.; Hiebert Bryan; Hallberg Ernest T.; Cummings Anne L. 《Canadian Metallurgical Quarterly》1989,36(4):395
We examined the conceptualizations of 23 (11 experienced and 12 novice) counselors, with respect to general counseling process and specific client concerns by means of a two-part conceptual mapping task (CMT). Analyses of the CMT data revealed an interaction effect of counselor experience and generality of conceptual task on the extensiveness of counselor conceptualizations. Experienced counselors displayed slightly more extensive conceptualizations on the general CMT and less extensive conceptualizations on the specific CMT. This interaction effect was interpreted as evidence that experienced counselors possess extensive abstract, general knowledge of counseling that they use to conceptualize specific instances of counseling efficiently and parsimoniously. On the other hand, novice counselors, who lack such abstracted knowledge, engage in more extensive, unique conceptual work for each separate client. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
114.
To determine how reservoir ageing affects sauger Sander canadense spawning locations in Lewis and Clark Reservoir, we quantified riverine habitat and determined sauger spawning locations during recent years (2003–2004) and compared these results to historic (1950–1966) habitat conditions and spawning locations. The riverine habitat above the reservoir, which was historically homogeneous, has developed into two distinct areas: the upstream remnant river reach, characterized by a distinct main channel, and cold and clear water from the hypolimnetic discharge from the upstream reservoir, and the downstream delta section, which has abundant side channels and backwater areas and is warmer and more turbid water than the remnant reach. Sauger spawning locations have shifted markedly in the last 50 years. Sauger historically spawned in the upper reaches of this system, near Fort Randall Dam. However, in 2003, we found that sauger spawned in the lower delta reach and avoided the remnant reach. This shift likely occurred concomitantly with the development of the novel delta habitat. The delta likely functions more similarly to the historic remnant reach of this system (warmer temperature, turbidity, active meandering, complex habitats, etc.), indicating that sauger prefer to spawn in areas with historic riverine function. Thus, future management activities intended to enhance sauger populations should focus on the restoration of riverine function, such as that provided by emerging reservoir deltas, which may mimic pre‐impoundment conditions on the Missouri River. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
115.
Jongho Lee Carmel Majidi Bryan Schubert Ronald S Fearing 《Journal of the Royal Society Interface》2008,5(25):835-844
Gecko-inspired microfibre arrays with 42 million polypropylene fibres cm(-2) (each fibre with elastic modulus 1 GPa, length 20 microm and diameter 0.6 microm) were fabricated and tested under pure shear loading conditions, after removing a preload of less than 0.1 N cm(-2). After sliding to engage fibres, 2 cm2 patches developed up to 4N of shear force with an estimated contact region of 0.44 cm2. The control unfibrillated surface had no measurable shear force. For comparison, a natural setal patch tested under the same conditions on smooth glass showed approximately seven times greater shear per unit estimated contact region. Similar to gecko fibre arrays, the synthetic patch maintains contact and increases shear force with sliding. The high shear force observed (approx. 210 nN per fibre) suggests that fibres are in side contact, providing a larger true contact area than would be obtained by tip contact. Shear force increased over the course of repeated tests for synthetic patches, suggesting deformation of fibres into more favourable conformations. 相似文献
116.
Bryan S. Krall Robert J. Bartelt Cara J. Lewis Douglas W. Whitman 《Journal of chemical ecology》1999,25(11):2477-2494
Adult Cosmopepla bimaculata discharge a volatile secretion from paired ventral metathoracic glands (MTG) when disturbed. Collected volatiles were similar in both sexes and consisted of n-tridecane (67%), (E)-2-decenal (12%), (E)-2-decenyl acetate (12%), (E)-2-hexenal (3%), hexyl acetate (2%), n-dodecane (2%), a tridecene isomer (1%), and n-undecane, n-tetradecane, and n-pentadecane (all <1%). In addition, undisturbed males produced a novel insect compound, (E)-8-heneicosene, whose function is unknown. The MTG secretion emerges as an enlarging droplet, which is held in place by a cuticular projection and a pleural scent area consisting of specialized rough cuticle surrounding the gland opening. Insects can selectively discharge from either the right or left gland or both glands simultaneously, can control the amount of fluid ejected, and can resorb the ejected secretion droplet back into the gland reservoir. In feeding trials, killdeer (Charadrius vociferous), starlings (Sturnus vulgaris), robins (Turdus migratorius), and anole lizards (Anolis carolinensis) rejected or demonstrated aversion to feeding on the bugs. Furthermore, bugs that lacked the secretion were more susceptible to predation than bugs with secretion, suggesting that the secretion functions in defense against predators. 相似文献
117.
The symptoms of poor product data management (PDM), data visibility, accessibility and reliability, are evident in many engineering environments. Data discipline has been lost in the proliferation of computer-based tools in a fragmented product development lifecycle. In this paper the authors try to isolate the golden rules of PDM. Process management and product structure management procedures have been identified. By embodying these, one can bring discipline to the management of product data. In application, implementation of `success' is limited by the ability of the technology. A balance is necessary between enablers and business requirements that may demand functionality beyond the cost effective operational parameters of the technology. Technology solutions must be driven by business needs, where the functionality and features of any particular solution are in line with the objectives of the implementation 相似文献
118.
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120.
LaHoste Gerald J.; Wigal Tim; King Bryan H.; Schuck Sabrina E.; Crinella Francis M.; Swanson James M. 《Canadian Metallurgical Quarterly》2000,8(1):125
Chronic treatment with neuroleptic drugs such as haloperidol (HAL) can result in a syndrome of abnormal involuntary movements known as tardive dyskinesia (TD). The authors have obtained evidence that TD in humans is reduced in patients also taking anticonvulsant drugs, primarily carbamazepine (CBZ). To test for a causal role of CBZ in this effect, the authors quantified abnormal movements elicited by dopamine (DA) receptor stimulation in rats (Rattus norvegicus) withdrawn from chronic treatment with HAL or CBZ alone or in combination. The expected increased behavioral responsiveness to combined D1/D2 stimulation in rats treated with HAL for 8 weeks was significantly attenuated by chronic CBZ, which also attenuated behavioral responsiveness in otherwise untreated rats. Striatal D2 DA receptor density was elevated in rats treated chronically with HAL but unaffected by CBZ. Striatal D1 DA receptor density was elevated by chronic CBZ but unaffected by HAL. These findings suggest that by reducing DA supersensitivity, CBZ may be useful in treating TD and other hyperdopaminergic states. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献