诱惑系统架构师与电源供应商的数字电源技术

数字电源指望通过改善维护成本和可靠性、降低电源元件成本、简化BOM来降低系统电源总成本。设计者必须为传统的笨拙电源子系统增加智能。数字电源控制与管理IC有助于这些目标的实现。     

Gait function in spastic hemiparetic patients walking barefoot, with firm shoes, and with ankle-foot orthosis

Cortical spreading depression is a wave of electrical and biochemical changes that spreads across the cerebral cortex. It has been hypothesized to be an important underlying cause of the visual disturbances occurring during the migraine aura, but this is difficult to test in animals or humans. We created a computational model of cortical spreading depression and found that during the wave of biochemical changes the spatial pattern of neural activity broke up into irregular patterns of lines and small patches of highly activated elements. The corresponding visual disturbances that would be produced by these patterns of neural activity resemble the hallucinations reported during the migraine aura, providing strong support for the cortical spreading depression hypothesis of migraine. The model also makes the testable prediction that these hallucinations move at an exponentially increasing speed across the visual field.     

Input and central processing expressed in ERP and heart rate changes to rare target and rare nontarget stimuli

Whether late positive components of event-related potentials (ERPs) parallel changes in heart rate (HR) indicative of attention/orienting to rare stimuli has been debated. In the present study, a three-stimulus design was used, with rare target, rare nontarget, and frequent standard stimuli delivered under identical conditions except that instructions to subjects described the targets to which subjects should respond but did not describe the nontargets. In Experiment 1, stimuli varied among modalities; in Experiment 2, auditory stimuli were employed. Both ERPs and HR were consistent with automatic processing preceding two stages of controlled processing. Rare stimuli evoked larger parietal P300 and initial HR deceleration than standards. Presumably because of load-reducing effects of long interstimulus intervals, targets and nontargets were not distinguished before a late slow wave and a late phase of HR acceleration. Neither rare stimulus elicited a recognizable frontal P3a.     

The heterogeneous character of the dilute acid hydrolysis of crystalline cellulose. III. Kinetic and X-ray data

Thirteen prehydrolyzed samples of cellulose, including native, mercerized, and regenerated materials were hydrolyzed in 1% and 1.5% sulfuric acid at 160, 170, and 180°C. Pseudo first-order rate constants and weight average degrees of polymerization were determined for each sample. For all cellulose samples, data from several experiments were used to determine the dependence of the rate of hydrolysis on sulfuric acid concentration. The results obtained in this study indicate that Sharples' end-attack model is consistent with kinetic data for the hydrolysis of cellulose II samples, but is not applicable to the hydrolysis of cellulose I samples. X-ray diffraction analyses indicated that, for native and mercerized cellulose samples, structural changes during dilute acid hydrolysis are not significant. However, data for rayon indicated that such changes may need to be taken into account in analysis of the reaction kinetics.     

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