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81.
82.
Campbell P.M. Greub H.J. Garg A. Steidl A. Carlough S. Ernest M. Philhower R. Maier C. Kraft R.P. McDonald J.F. 《Very Large Scale Integration (VLSI) Systems, IEEE Transactions on》1998,6(1):52-55
A digital voltage-controlled oscillator (VCO) is described which uses frequency multiplication and division to achieve very wide bandwidth. The VCO uses current-mode logic and does not require reactive elements such as inductors, capacitors or varactors. A novel, fully symmetric exclusive-OR (XOR) circuit was developed which uses product pairs and emitter-coupled logic. To achieve the highest performance possible, the critical path is symmetric and special physical design techniques were developed to promote matched-capacitance. The maximum measured frequency was 13.66 GHz. The chip occupies 1.9 mm×1.6 mm and dissipates 2.45 W at a supply voltage of -6.0 V. With a measured frequency range from 1.25 to 13.66 GHz, this circuit has the widest bandwidth reported in the literature for any VCO, digital or analog 相似文献
83.
During spatial navigation, women typically navigate an environment using a landmark strategy, whereas men typically use an orientation strategy. To examine the as yet unknown effects of sexual orientation on these normative sex differences, this study required 80 healthy heterosexual and homosexual adult men and women to provide directions from experimental maps for 4 routes. The frequency and type of strategy used by each participant were computed. Expected sex differences were demonstrated, and a robust cross-sex shift was shown by homosexual men in using landmarks. This remained after controlling for differences in mental rotation, directional sense, and general intelligence. The findings may limit the number of putative neurodevelopmental pathways responsible for sex differences in navigation strategy utility. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
84.
Arvind Narurkar Pai-Chang Sheen Ernest L. Hurwitz Matthew A. Augustine 《Drug development and industrial pharmacy》1987,13(2):319-328
The particle size reduction of chlorthalidone by fluid energy milling, Alpine milling and Fitzpatrick milling were evaluated. The desired particle size was achieved by both the fluid energy milling and Alpine milling processes. Alpine mil1ing, however, is a more complex process and is susceptible to product decomposition, whereas fluid energy milling is a simple and efficient process without any risk of product decomposition. The desired particle size cannot be achieved by Fitzmilling because of the low probability of impaction force on particles. The dissolution rate of the chlorthalidone from chlorthalidone/propranolol hydrochloride tablets (25/80 mg) prepared with fluid energy milled chlorthalidone was significantly better than the tablets prepared with Fitzpatrick - milled chlorthalidone. The minimum effective specific surface area of chlorthalidone needed for maximum dissolution in water was found to be around 3.5 m2/g. 相似文献
85.
A. Ernest MacGee 《Journal of the American Ceramic Society》1928,11(11):858-867
Porosity, crushing strength, elasticity, specific gravity, transverse strength, thermal expansion, impact strength, and resistance to heat shock were determined on five glass tank block refractory bodies. Ability to resist heat shock was successfully predicted from the elasticity, transverse strength, thermal diffusivity, and thermal expansion values. 相似文献
86.
Tooth structure loss apical to preparations for fixed partial dentures when using self-limiting burs
BACKGROUND: Endovascular treatment of cerebral aneurysms is a relatively new method, since only a few animal models and data are available. The present experimental study was performed in order to establish an appropriate aneurysm animal model, to determine the rate of permanent occlusion, and to correlate radiologic and morphologic findings. METHODS: End-to-side anastomoses of both common carotid arteries were performed microsurgically in 53 chinchilla rabbits. Venous pouches were adapted into the newly created bifurcation, resulting in berry-shaped aneurysms comparable to those in humans with regard to size and hemodynamics. Platinum and tungsten coils were used for endovascular embolization. The embolized aneurysms were investigated radiologically and morphologically. RESULTS: Twenty-three carotid bifurcation aneurysms remained for testing endovascular therapeutic approaches. The morphologic examinations of 13 embolized aneurysms revealed in no instance a complete obliteration, even in the three cases that were considered completely embolized according to angiographic criteria. CONCLUSIONS: The present animal model is an optimal tool for endovascular research. Analysis of the results of coil obliteration revealed a considerable discrepancy between radiologic and pathologic findings. The radiologic degree of aneurysm occlusion was overestimated. 相似文献
87.
Grych John H.; Jouriles Ernest N.; Swank Paul R.; McDonald Renee; Norwood William D. 《Canadian Metallurgical Quarterly》2000,68(1):84
Children exposed to interparental violence have been characterized by an array of psychological problems, but findings regarding the precise nature of these problems have been inconsistent. This study used cluster analysis to determine whether distinct patterns of adjustment could be identified in 228 8- to 14-year-old children residing in battered women's shelters. Five such patterns emerged: multiproblem–externalizing, multiproblem–internalizing, externalizing, mild distress, and no problems reported. This solution was cross-validated in independent halves of the sample and was similar for boys and girls. Differences among the clusters on relevant family and demographic variables were examined, and it was found that the clusters could be distinguished on the basis of the frequency of children's exposure to interparental violence, parent–child aggression, and children's appraisals of interparental conflict. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
88.
Examined racial E effects in counseling-like interviews employing the verbal operant-conditioning paradigm. The general objective was to determine whether significant differences in the conditionability of 12 Black and 12 White female college students, as measured by their emission of positive and negative self-reference emotional affect statements, would obtain when the verbal reinforcement was provided by 2 Black and 2 White Es. A postexperimental inquiry assessed Ss' perceptions of the interviews and their level of awareness of the Es' to influence their verbal behavior. While no definitive conclusions were reached, this study demonstrates that the verbal operant-conditioning paradigm can be used to investigate racial effects on verbal behavior in the counseling interview. Through the use of multiple, biracial Es and Ss, this study goes a step further than other verbal operant-conditioning studies that have explored racial E effects. The absence of significant differences in the E-S racial interaction suggests that race, per se, may not be the most important variable in the E-S (or counselor-client) relationship. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
89.
90.