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991.
Patterson Teresa A.; Alvarado Maria C.; Warner Irene T.; Bennett Edward L.; Rosenzweig Mark R. 《Canadian Metallurgical Quarterly》1986,100(6):856
Stages of formation of memory and the roles of different forebrain structures in memory formation were investigated by injecting various agents into the brains of chicks close to the time of peck-avoidance training. With L-glutamate injected bilaterally into the hyperstriatum 5 min pretraining, retention was good 1 min posttraining but significantly impaired at 5 min and each subsequent time point from 10 min to 24 hr. With ouabain, retention declined more slowly, showing significant impairment at 15 min and thereafter. With any of 3 protein synthesis inhibitors, retention was still good 60 min posttraining but significantly impaired at 90 min. The 3 time courses of decline of retention are consistent with hypotheses of 3 sequentially dependent stages of memory formation. It appears that both the medial hyperstriatum and the lateral neostriatum are required for formation of memory. Agents that are specific for a presumed stage of memory formation and whose action is restricted spatially should help reveal the roles of different brain structures in different stages of memory formation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
992.
The authors argue against a purely behavioral definition of praise as verbal reinforcement in favor of the view that praise may serve to undermine, enhance, or have no effect on children's intrinsic motivation, depending on a set of conceptual variables. Provided that praise is perceived as sincere, it is particularly beneficial to motivation when it encourages performance attributions to controllable causes, promotes autonomy, enhances competence without an overreliance on social comparisons, and conveys attainable standards and expectations. The motivational consequences of praise also can be moderated by characteristics of the recipient, such as age, gender, and culture. Methodological considerations, such as including appropriate control groups and measuring postfailure outcomes, are stressed, and directions for future research are highlighted. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
993.
Peter Pirsch Carsten Reuter Jens Peter Wittenburg Mark B. Kulaczewski Hans-Joachim Stolberg 《The Journal of VLSI Signal Processing》2001,29(3):157-165
Architectural concepts are presented aimed at future multimedia processing schemes. Starting from an analysis of current and future multimedia applications, specific computational requirements are derived. It will be shown that multimedia applications benefit from an exhaustive and flexible exploitation of parallelism. Three architectural concepts—reconfigurable computing, simultaneous multithreading, and associative controlling—are presented, and their potential to increase further the performance on future multimedia applications is investigated. 相似文献
994.
Mark D. Vaudin 《Journal of research of the National Institute of Standards and Technology》2001,106(6):1063-1069
Preferred crystallographic orientation, or texture, occurs almost universally, both in natural and man-made systems. Many components and devices in electronic and magnetic systems are fabricated from materials that have crystallographic texture. With the rapidly increasing use of thin film technology, where sharp axisymmetric crystallographic texture normal to the film plane is frequently observed, the occurrence and impact of texture are rising. Thin film applications in which the texture of the material plays a key role in determining properties and performance are broad: complex oxides in random access memory devices, ZnO thin film resonators for cell phone applications, metallic alloys in magnetic recording media, and Al and Cu interconnects in integrated circuits are but a few examples. Texture is established during the synthesis or post-synthesis heat treatment of a material and thus has a strong dependence upon processing history. Accurate measurement of texture is not simple and a variety of tools and approaches are being actively employed in texture studies. X-ray, neutron and electron diffraction based techniques are practiced around the world at varying levels of complexity with regard to equipment and analysis methods. Despite the well-documented existence of these varied approaches, many reported texture measurements on electronic materials are based solely on the relative intensities of conventional θ-2θ x-ray diffraction peaks, which typically yield inaccurate results. NIST has developed quantitative texture measurement techniques that employ equipment commonly available in most industrial and academic settings. A number of examples of texture measurement in ceramic and metal systems will be presented, taken from the historical development and application of these techniques at NIST over the past 7 years. 相似文献
995.
996.
997.
The gradual climate change symptoms in many places on Earth have been observed during the last 20 years. There is a significant increase in frequency and extremity of meteorological and hydrological events (EEA, 2007) that lead to distinct excess or lack of water in landscape. These phenomena affect not only actual quantity of water but also its quality with direct and indirect impacts on aquatic organisms. From the environmental impact point of view, drought events are considered to be more dangerous due to their medium-term to long-term characteristics and large spatial impacts. However, this study presents that the particular flood event had significantly greater impact on water quality than the period of drought even if for only a very short time The paper reviews changes in water quality with all its consequences during selected extreme hydrological situations in the Czech Republic in last 10 years and compares them with the knowledge of impacts of floods and droughts on water quality collected from literature. 相似文献
998.
We explore the practical limits on throughput imposed by timing in a long, self-timed, circulating pipeline (ring). We consider models with both fixed and random delays and derive exact results for pipelines where these delays are fixed or exponentially distributed random variables. We also give relationships that provide upper and lower bounds on throughput for any pipeline where the delays are independent random variables. In each of these cases, we show that the asymptotic processor utilization is independent of the length of the pipeline; thus, linear speedup is achieved. We present conditions under which this utilization approaches 100%.This work was supported in part by NSF Grant MIP-8705454, U.S. Army Research Office—Durham Contract DAAG29-85-K-0191, and DARPA Contract N00014-82-K-0549. 相似文献
999.
Proposes an interactional model of independence that focuses on personal and environmental variables. Personal variables in rehabilitation include physical abilities, knowledge and skills, and values and goals. Environmental variables include the physical environment, social networks and service programs, and the system of laws, policies, and public attitudes that guide institutional responses to people with disabilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
1000.
Hugo E. Acosta-Martinez Susan M. Gourvenec Mark F. Randolph 《Soils and Foundations》2008,48(2):247-254
Shallowly embedded skirted foundations are an attractive alternative to piles for jacket structures and buoyant facilities as they can resist uplift but are cheaper to install than deep foundations. Bearing capacity of shallow skirted foundations in compression is moderately well understood while there is still considerable uncertainty over uplift capacity, particularly for loading sustained over a period of time. This paper reports results from beam centrifuge tests on a shallow skirted foundation in clay, subjected to uplift and compression. Rapid and sustained loading is considered and the effects of consolidation stress level and stress history on undrained capacity and sustained load response are reported. 相似文献