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Comments on an article by W. B. Miller (see record 1984-17604-001) that asserts that humans have moved from a passive adaptation to an active regulation of reproduction. Although Miller addressed the psychological sequelae of increasing control over reproduction, it is argued that he oversimplified the psychological contingencies of perceived high choice in reproduction. Some of the more recent technological advances appear to facilitate choice while only nominally increasing the chance of conception. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
33.
Rain-induced crosspolarisation on an 11.6 GHz satellite slant path is successfully predicted, in both magnitude and phase, by using simultaneous data from a dual-linear polarisation radar. Neither mean nor stochastic canting angles are invoked in the analysis.  相似文献   
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Standard measurement devices do not normally provide detailed information about flows in porous media because either they are too intrusive (e.g., hot/film wire anemometers) or because the solid phase impedes their physical access to the flow as in the case of laser Doppler anemometers or particle image velocimetry (PIV). In this study, a Metflow ultrasonic velocity profiler (UVP) is used to measure instantaneous velocity fields within porous media composed of plastic balls packed in a cubic pattern. Simple considerations of the ultrasound beam properties and propagation, plus a comparison with measurements performed by a PIV system, demonstrate that UVP devices are suitable for such a purpose.  相似文献   
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Multidimensional ultrasonic imaging for cardiology   总被引:2,自引:0,他引:2  
Previous extensions of two-dimensional ultrasonic imaging to three dimensions used lattice diagrams which give measurement information, but no anatomic detail. The authors conducted three sets of experiments to test the hypothesis that complete acoustic backscatter data should be retained to produce useful information about heart structure and function. First, in vitro compound B-scans were taken under ideal conditions; second, in vitro rotating conventional sector scans were taken to test clinically applicable methods; and third, clinical in vivo rotating conventional sector scans were taken of a human volunteer. It is concluded that the resulting images show details of cardiac anatomy and have great clinical promise. Interactive analysis and surface and volume displays give context and perspective information which should improve diagnostic accuracy, communication with noncardiologists and yield more precise measurements of anatomical structure and function  相似文献   
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Bashir  S.O. McEwan  N.J. 《Electronics letters》1985,21(24):1141-1143
9 GHz measurements of effects of dust accretion on the surface of a reflector antenna confirm an earlier prediction of a larger gain reduction when the dust layer covers half the area. Crosspolarisation levels were higher than expected theoretically. Deposits on the primary feed also cause high crosspolarisation.  相似文献   
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This study is an examination of the interaction of humor and gender in moderating relationships among perceived stress, anxiety, and physical symptoms. Introductory psychology students (70 women, 61 men) completed self-report scales measuring perceived stress, humor, and symptomology. Multiple regression analyses revealed a moderating effect for humor between stress and anxiety, but only for men. When humor was low, a positive relationship was obtained between stress and anxiety; no relationship existed when humor was high. No gender differences were found in the significant moderating effect of humor between stress and physical symptoms. When humor was low, stress was related to physical symptoms; no relationship was found when humor was high. Overall, the findings supported humor as a moderator of stress; gender differences also existed for some outcomes.  相似文献   
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A tunable band‐notch printed monopole antenna is presented, exhibiting a wide impedance bandwidth from 1.5 to 5.5 GHz with good impedance matching (VSWR ≤ 2) and a tunable rejected frequency band from 2.38 to 3.87 GHz. The band‐notching is achieved by adding an inner chorded crescent element within a driven element of a similar shape. By varying the value of the varactor, which is placed between the inner and outer arcs, the desired variable rejected can be obtained. Simulated and measured results show wide impedance bandwidth with a tunable band notch, stable radiation patterns, and consistent nearly constant gain. The antenna is suitable for mobile and portable applications. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:403–412, 2015.  相似文献   
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