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951.
Objective: To examine the association of parent behavior with infant distress during a potentially painful medical procedure. A second aim was to investigate the association of parent chronic pain and psychological problems with parent behavior and infant distress during the procedure. Design: Population-based cohort study with both cross-sectional and prospective measurements. Main Outcome Measures: Video recordings of 275 parents and their 14-month-old infant undergoing venipuncture were coded with an observational instrument to yield measures of infant distress behaviors and parent behaviors, such as reassuring, showing empathy, praising, and distracting. Parent chronic pain and psychological problems were assessed through questionnaires. Results: Infants cried 58% of procedure duration. Parent reassuring occurred 34% of procedure duration, and parent distracting occurred 37% of procedure duration. Infant distress was positively related to parent reassuring and negatively related to parent praising. Parent chronic pain was related to increased parent distracting but not to parent reassuring. Parent psychological problems were not associated with parent behavior and infant distress. Conclusion: Parent behavior rather than psychological traits is related to increased venipuncture distress in young infants. This finding suggests that the focus should be on interventions based on behavior modification. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
952.
This paper analyzes fade slope for the Alaska, Florida, and New Mexico Advanced Communications Technology Satellite (ACTS) propagation data at 20 and 27.5 GHz for the first two years of the experiment (December 1, 1993-November 30, 1995). The propagation experiment will continue to collect data for at least another 21 months. Fade slope is examined on a statistical basis for the three sites. The Florida and New Mexico receiver sites have very different weather characteristics but almost identical elevation angles, while the Alaska receiver terminal has an extremely low elevation angle. The cumulative statistics illustrate the relationship between fade slope, fade level, transmission frequency, and elevation angle for all three sites  相似文献   
953.
Instruction Set Extensions for MPEG-4 Video   总被引:2,自引:0,他引:2  
This paper describes instruction set extensions for the acceleration of MPEG-4 algorithms on programmable (RISC-) CPUs. MPEG-4 standardizes audio and video compression schemes for a variety of bit rates and scenarios. As MPEG-4 targets a much broader range of different applications than previously defined hybrid video coding standards like H.263 or MPEG-2, it employs a much higher number of different algorithms and coding modes. Therefore, MPEG-4 implementations will require a more software-oriented approach to be efficient. However, the total computational load for an optimized implementation of an MPEG-4 video codec is expected to exceed the performance levels of today's multimedia signal processors, making further hardware acceleration a necessity. For that purpose, we propose a number of instruction set extensions that add function-specific blocks to the data path of a CPU. These dedicated modules are highly adapted to the most computation-intensive processing schemes of MPEG-4, such as DCT, motion compensation, padding, shape coding, or bitstream parsing. The increased functionality of basic instructions results in a significant speed-up over standard RISC instruction sets, thus making MPEG-4 implementations feasible on programmable processor platforms. Possible target architectures include VLIW multimedia processors, MIMD-style multiprocessors, or coprocessor architectures  相似文献   
954.
We have demonstrated top-gate polymer field-effect transistors (FETs) with ultra-thin (30–50 nm), room-temperature crosslinkable polymer gate dielectrics based on blending an insulating base polymer such as poly(methyl methacrylate) with an organosilane crosslinking agent, 1,6-bis(trichlorosilyl)hexane. The top-gate polymer transistors with thin gate dielectrics were operated at gate voltages less than ?8 V with a relatively high dielectric breakdown strength (>3 MV/cm) and a low leakage current (10–100 nA/mm2 at 2 MV/cm). The yield of thin gate dielectrics in top-gate polymer FETs is correlated with the roughness of underlying semiconducting polymer film. High mobilities of 0.1–0.2 cm2/V s and on and off state current ratios of 104 were achieved with the high performance semiconducting polymer, poly(2,5-bis(3-alkylthiophen-2yl)thieno[3,2-b]thiophene.  相似文献   
955.
Performance predictions from a new optical amplifier model   总被引:1,自引:0,他引:1  
We present results of a new model of semiconductor laser amplifiers which differs from previous analyses in that it includes the spectral dependence of material gain and spontaneous emission. The implications of low facet reflectivities are explored in some detail. For reflectivities below about 1 percent, the increased spontaneous emission imposes more stringent limits on current density than realized hitherto. If thermal runaway is to be avoided and gains in the range of 20-30 dB are to be achieved without excessive currents, then facet reflectivities on the order of 0.1-1 percent are probably optimal. Another consequence of including the spectral dependence is that wavelengths longer than that corresponding to the unsaturated gain peak are predicted to experience enhanced amplification at high input powers by comparison to shorter wavelengths.  相似文献   
956.
A new method is presented for determining the semiconductor-laser linewidth-broadening factor ?. Measurements on 1.5 ?m devices suggest that ? decreases with decreasing laser length. 300 ?m-long devices emitting at 1.3 and 1.5 ?m were found to have similar values of ? (6.6 cf. 6 4), but at 0.85 ?m significantly lower results were measured (2.8)  相似文献   
957.
958.
The spectral behaviour of a buried crescent GaInAsP laser emitting at 1.52 ?m was investigated. Under modulation conditions, partitioning between the lasing modes was observed. When the light was transmitted through 27 km of monomode fibre, jitter consistent with the partitioning was observed.  相似文献   
959.
960.
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