Risk aversion in rats (Rattus norvegicus) under varying levels of resource availability.

Five male Wistar rats chose between a certain prospect and an uncertain prospect having equal expected value under varying levels of resource (water) availability. In contrast to results found with granivorous birds and common shrews (Sorex araneus), the rats did not switch from risk aversion (choosing the certain prospect) to risk preference (choosing the uncertain prospect) as resource availability varied from surplus to deficit, even though deficits were maintained for extended periods of time. Rather, Ss displayed an approximately constant level of risk aversion throughout. Explanations for these differences are offered in terms of procedural differences between this and earlier studies and in terms of differential behavioral patterns of relatively large organisms with large internal resource stores relative to their daily resource requirements. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

ORGANIC METAMORPHISM IN THE LOWER MISSISSIPPIAN-UPPER DEVONIAN BAKKEN SHALES — II: SOXHLET EXTRACTION1

In this paper, we report on Soxhlet extraction (and subsequent related analyses) of 39 Lower Mississippian-Upper Devonian Bakken shales from the North Dakota portion of the Williston Basin, and analyses of 28 oils from the Basin. Because of the influence of primary petroleum migration, no increase in the relative or absolute concentrations of hydrocarbons or bitumen was observed at the threshold of intense hydrocarbon generation (TIHG), or during mainstage hydrocarbon generation in the Bakken shales. Thus, the maturation indices that have been so useful in delineating the TIHG and mainstage hydrocarbon generation in other studies were of no use in this study, where these events could clearly be identified only by Rock-Eva1 pyrolysis data. The type of primary petroleum migration operative in the Bakken shales led to the selective concentration of certain compound types in the oils of the basin, as well as the selective concentration of certain compound types in the shale extracts. The compositional differences between the crude oils and shale extracts provide evidence of the primary migration mechanism operative in this case, which is believed to have been gaseous solution, although the actual expulsion of oil from the rock, if observed, would probably have appeared to be bulk phase migration. Gaseous-solution bulk-phase primary petroleum migration also left organic-geochemical imprints on the Bakken shales, observable by Soxhlet extraction and to a lesser extent by pyrolysis. The data of this study demonstrate that primary petroleum migration is a very efficient process. Four distinctive classes of saturated hydrocarbon gas chromatograms from the Bakken shales arose from facies, maturation, and primary migration controls. As a consequence of maturation, the percentage of saturated hydrocarbons increased in the shale extract at the expense of decreases in the resins and asphaltenes. Measurements involving resins and asphaltenes appear to be excellent maturation indices in the Bakken shales. Two different and distinct organic facies were present in immature Bakken shales. Rock-Eval pyrolysis analysis was a critical research tool in this study; however, combined use of pyrolysis and Soxhlet extraction allowed organic-geochemical features to be distinguished which would not have been possible by using either analysis alone.     

Egg Thiamine Status of Lake Ontario Salmonines 1995–2004 with Emphasis on Lake Trout

Alewives (Alosa pseudoharengus), the major prey fish for Lake Ontario, contain thiaminase. They are associated with development of a thiamine deficiency in salmonines which greatly increases the potential for developing an early mortality syndrome (EMS). To assess the possible effects of thiamine deficiency on salmonine reproduction we measured egg thiamine concentrations for five species of Lake Ontario salmonines. From this we estimated the proportion of families susceptible to EMS based on whether they were below the ED20, the egg thiamine concentration associated with 20% mortality due to EMS. The ED20s were 1.52, 2.63, and 2.99 nmol/g egg for Chinook salmon (Oncorhynchus tshawytscha), lake trout (Salvelinus namaycush), and coho salmon (Oncorhynchus kisutch), respectively. Based on the proportion of fish having egg thiamine concentrations falling below the ED20, the risk of developing EMS in Lake Ontario was highest for lake trout, followed by coho (O. kisutch), and Chinook salmon, with the least risk for rainbow trout (O. mykiss). For lake trout from western Lake Ontario, mean egg thiamine concentration showed significant annual variability during 1994 to 2003, when the proportion of lake trout at risk of developing EMS based on ED20 ranged between 77 and 100%. Variation in the annual mean egg thiamine concentration for western Lake Ontario lake trout was positively related (p < 0.001, r² = 0.94) with indices of annual adult alewife biomass. While suggesting the possible involvement of density-dependent changes in alewives, the changes are small relative to egg thiamine concentrations when alewife are not part of the diet and are of insufficient magnitude to allow for natural reproduction by lake trout.     

让LED灯符合EMC及电能质量标准要求

引言 作为白炽灯的替换品,LED灯近年来才开始推出市场,但却面临着诸多难题.由于将LED功率驱动电路装入标准灯壳具有难度,因此早期的一些LED灯并没有内部滤波器,也就谈不上符合EMC标准.     

智能型激光控制器提高灵活性并节省空间

激光二极管是宽带调幅光纤发射系统的核心器件。光纤系统依赖于激光的稳定性,但未受调节控制的激光二极管特性却常因制造误差、温度和使用日久所造成的参数改变而变得不稳定。因此,光纤通信系统需要专用电路来控制重要的激光二极管参数,以确保它们稳定操作。虽然激光控制电路都     

Possible amotivational effects following marijuana smoking under laboratory conditions.

Human participants earned money by responding on a progressive-ratio (PR) schedule (initial value $50) or received money without responding on a fixed-time (FT) schedule. During the session, participants could terminate the PR schedule and initiate an FT 200-s schedule. In Experiment 1, increases in monetary value produced increased number of responses, time spent, and money earned in the PR component. In Experiment 2, marijuana smoking produced potency-related reductions in the number of responses, time spent, and money earned in the PR component, effects that can be interpreted as amotivational. Increasing the monetary value of the reinforcer diminished the acute marijuana effects on PR responding, suggesting that marijuana exerted an effect primarily on reinforcers of a smaller magnitude. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Synthesis of Silver Nanocrystallites by a New Thermal Decomposition Method and Their Characterization

We formed silver nanocrystallites by the thermal decomposition of a Ag+¹‐oleate complex, which was prepared by a reaction with AgNO₃ and sodium oleate in a water solution. The resulting monodispersed silver nanocrystallites were produced by controlling the temperature (290 °C). Transmission electron microscopic (TEM) images of the particles showed a 2‐dimensional assembly of the particles with a diameter of 9.5 ± 0.7 nm, demonstrating the uniformity of these nanocrystallites. An energy‐dispersive X‐ray (EDX) spectrum and X‐ray diffraction (XRD) peaks of the nanocrystallites showed the highly crystalline nature of the silver structure. We analyzed the decomposition of the Ag⁺¹‐oleate complex using a Thermo Gravimetric Analyzer (TGA) and observed the crystallization process using XRD.     

Evaluating the transfer of technology between application domains: a critical evaluation of the human component in the system

Technology can take many forms from the development of sophisticated electronics to the application of basic procedural principles. Technology transfer can also take several forms, however, in this case, it is the transfer of technological principles between application domains that is of primary interest. This paper presents a framework (the Five ‘M’s framework) that can be used to consider the likely success of technology transfer. The framework is based upon a sociotechnical system approach. The framework is illustrated with an evaluation of the introduction of intelligent cruise control into motor vehicles. It is argued that this is a technological concept first developed as an aerospace application in the form of the autopilot. In this case, it is argued that the transfer of this technology in its current form may potentially compromise safety.