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71.
Huang T.C. Hausken T. Lee K. Dagli N. Coldren L.A. Myers D.R. 《Photonics Technology Letters, IEEE》1989,1(7):168-170
A waveguide crossing optical switch using the depletion edge translation concept is described. By using a single AlGaAs/GaAs material growth and ion implantation technology, an impedance discontinuity is formed at the intersection of two waveguides. Switching operation has been observed, and a high-speed, small-device-size, and high-extinction-ratio optical switch are expected 相似文献
72.
Rokers Bas; Mercado Eduardo III; Allen M. Todd; Myers Catherine E.; Gluck Mark A. 《Canadian Metallurgical Quarterly》2002,116(1):48
Septohippocampal interactions determine how stimuli are encoded during conditioning. This study extends a previous neurocomputational model of corticohippocampal processing to incorporate hippocamposeptal feedback and examines how the presence or absence of such feedback affects learning in the model. The effects of septal modulation in conditioning were simulated by dynamically adjusting the hippocampal learning rate on the basis of how well the hippocampal system encoded stimuli. The model successfully accounts for changes in behavior and septohippocampal activity observed in studies of the acquisition, retention, and generalization of conditioned responses and accounts for the effects of septal disruption on conditioning. The model provides a computational, neurally based synthesis of prior learning theories that predicts changes in medial septal activity based on the novelty of stimulus events. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
73.
PL Myers 《Canadian Metallurgical Quarterly》1997,8(6):701-707
Over the next decade, the impact of library synthesis will play a major role in shortening the lead optimization phase of drug discovery. The prognosis for combinatorial chemistry to discover fundamentally different new classes of therapeutically active small molecules against some of the more difficult biological targets is less certain. Expectations are high because the technology potentially allows us to sample available drug space by synthesizing all possible small molecule ligands (variously estimated to be between 10(30)-10(50) compounds). Some caution is advised, however, since, despite recent increases in high-throughput screening of substantially greater numbers of synthetic compounds and natural products, we are not routinely finding a plethora of new structures. The outcome may be that combinational chemistry offers us the ability to work faster on finding ligands for well-established tractable targets, such as G-protein-coupled receptors, ion channels or proteases, rather than, say, the more complex protein-protein interactions which from the majority of targets in signal transduction pathways. 相似文献
74.
75.
E Myers 《Canadian Metallurgical Quarterly》1986,33(6):1563-1566
76.
Examined whether antecedents are reactivated by anaphor, in 3 experiments with a total of 144 undergraduates, using additional control sentences and an alternative response time measure. Ss read a series of texts each containing a target item. Immediately after the last line of each text, the item was probed using a recognition task in Exp I and a naming task in Exp II. Ss were faster to respond to the item when the last line contained an anaphoric reference to it than when the last line referred to a different item from the text. Additional control conditions ensured that the effect was not due to semantic priming and that the probed item was not in working memory when the last line was encountered. Findings in Exp III, which compared reading and naming times when the last sentence continued the established topic with times when the last sentence changed the topic, suggest that previous evidence for reinstatement reflected interference from a change of topic in the last line rather than facilitation due to reinstatement of the probed item. It is suggested that the paradigm developed by G. McKoon and R. Ratcliff (see record 1981-24997-001) requires careful control of variables. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
77.
78.
MA Blank BL Ems GW Gibson WR Myers SK Berman RJ Phipps PN Smith 《Canadian Metallurgical Quarterly》1997,42(2):281-288
Mechanisms by which ketones potentiate manganese-bilirubin (Mn-BR)-induced cholestasis are unknown. The purpose of the present study was to investigate the effect of methyl isobutyl ketone (MiBK), a widely used ketonic solvent, at the level of the bile canalicular membrane (BCM) and to verify if altered membrane lipid dynamics could be involved in MiBK-potentiated Mn-BR cholestasis. Male Sprague-Dawley rats were exposed 4 hr/day for 3 days to MiBK vapors (200 or 600 ppm). Eighteen hours after the last exposure, manganese (Mn, 4.5 mg/kg) was given i.v. followed 15 min later by bilirubin (BR, 25 mg/kg). Rats were killed 30 min after BR; liver cell plasma membranes (bile canalicular and sinusoidal), microsomes, mitochondria, and cytosol were isolated by differential centrifugation. Lipids were extracted and cholesterol was measured in each fraction. After Mn-BR and MiBK exposure (600 ppm), results indicated a marked increase in BCM cholesterol content compared to rats exposed to air only. This increase was greater than that due to Mn-BR or MiBK given alone. Also, results indicated that cholesterol increased in a dose-related fashion in BCM after MiBK exposure, whereas PM cholesterol remained unaltered. To identify the source of the increased BCM cholesterol and to permit distinction between de novo cholesterol synthesis and subcellular shifts, the hepatic lipid pool was labeled in vivo with [3H]-cholesterol and [2-14C]-mevalonic acid, a cholesterol synthesis precursor. Results showed that after 600 ppm MiBK exposure, 14C-labeled cholesterol was greater than 3H-labeled cholesterol, indicating that the contribution of de novo cholesterol synthesis to the total cholesterol content of the various isolated hepatocellular fractions was more important than the contribution of intracellular pools. Therefore, increased BCM cholesterol content and enhanced accumulation of newly synthesized cholesterol appear to be involved in MiBK potentiation of Mn-BR-induced cholestasis. 相似文献
79.
J.F. Lyness BSc MSc PhD CEng MICE MIStructE W. R. C. Myers BA BSc PhD CEng MICE J. B. Wark BEng PhD 《Water and Environment Journal》1997,11(5):335-340
Flow measurements have been taken for steady and unsteady flows on a reach of a river having a compact compound channel. The 'single channel', 'divided channel' and 'lateral' distribution methods have been used to calculate conveyances for use in a one-dimensional unsteady flow model of the reach. Comparisons with measured flows show that the divided channel method and the lateral distribution method both underestimate floodplain flow depths. The lateral distribution method gives the closest accuracy in the relative depth range 0.15 ≤ Yr < 0.40. For large flow depths the single channel method becomes more accurate and slightly over-estimates flow depths.
The accuracy of unit width discharge distributions, calculated from the lateral distribution method are assessed by comparison with observed distributions for overbank flows. 相似文献
The accuracy of unit width discharge distributions, calculated from the lateral distribution method are assessed by comparison with observed distributions for overbank flows. 相似文献
80.
During 1979, CERN began to evaluate how interactive computer graphics displays could aid the analysis of high-energy physics experiments at the new Super Proton Synchrotron collider. This work led to PIONS, a 3D graphics system, which features the ability to store and view hierarchical graphics structures in a directed-acyclic-graph database. It is possible to change the attributes of these structures by making selections on nongraphical information also stored in the database. PIONS is implemented as an object-oriented message-passing system based on Small Talk design principles. It supports multiple viewing transformations, logical input devices, and 2D and 3D primitives. The design allows full use to be made of display hardware that provides dynamic 3D picture transformation. 相似文献