Transient hot-electron effect and its impact on circuit reliability

Transient hot-electron effect and its impact on circuit reliability are investigated. The rate of device decay is monitored as a function of the gate pulse transient period. Simulation results reveal that excess charges during a fast turn off time may cause an increase in the maximum substrate current. This, along with our experimental data, identifies that transient excess carrier may cause the enhancement of device degradation under certain stress conditions. The enhancement factor of the degradation is a function of the gate pulse transient time. Correlation between the analysis based upon AC/DC measurement and calculations based upon transient simulation are shown in the paper. Better agreement with experimental data is obtained by using the transient analysis and on chip test/stress structures. The correlation between AC and DC stress data is also shown based on the impact ionization model. A hot-electron design guideline is proposed based on the circuit reliability analysis. This guideline can help improve the circuit reliability without adversely effecting the circuit performance.     

Intraocular pressure fluctuations during scleral buckling surgery

PURPOSE: The purposes of this study are to measure real-time intraocular pressure (IOP) during scleral buckling and to determine the effects of elevated IOPs on ocular perfusion. PATIENTS AND METHODS: A standard 4-mm, 20-gauge infusion cannula was inserted through the pars plana, connected to a standard hemodynamic monitoring unit with an electronic pressure transducer, and calibrated. The authors measured real-time IOP in 20 eyes undergoing scleral buckling surgery for primary rhegmatogenous retinal detachments and determined the IOP required to close the central retinal artery. Pressure measurements were read from the monitor videoscreen intraoperatively and from a continuous paper tracing postoperatively. RESULTS: The patients ranged in age from 24 to 88 years (mean, 59.7 years). The highest IOP elevations occurred during scleral depression and cryopexy, ranging up to 210 mmHg (mean, 116 mmHg). Pressures at which the central retinal artery closed ranged from 48 to 110 mmHg (mean, 79.2 mmHg). Manipulations of the globes caused IOPs greater than the central retinal artery perfusion pressures in 13 of the 20 patients. The duration of pressures in excess of the central retinal artery perfusion pressure ranged from 6 to 402 seconds (mean, 118.8 seconds). There were no intraoperative or postoperative complications from the infusion cannula. CONCLUSIONS: Conventional scleral buckling surgery causes wide fluctuations in IOP and may impair ocular perfusion. Additional studies are needed to determine the long-term consequences of these pressure elevations.     

是天使？是魔鬼？——IE7正式版体验

10月19日,历经5年的等待,姗姗来迟的InternetExplorer7正式版终于出现在世人面前。有别于以往渐近式的改进,本次的IE7不管是外观,还是内涵,都发生了翻天覆地的变化。不过,资源占用情况依然不容乐观,本文将带你了解这一切。     

Estimation of failure intensity for the Weibull process

A Weibull process/non-homogeneous Poisson process is commonly used to analyze the failure behavior of repairable systems. The object of the present study is to obtain exact estimates of the failure intensity of this model at the time of n failures. The resulting MLE estimate is biased and the corrected version for biasedness along with some approximate estimates is given. An analytical and numerical comparison of the relative efficiencies of the MLE of the exact biased, approximated biased, exact unbiased and approximated unbiased of the intensity function is presented. It will be shown that for small n (n < 30) there is quite a large relative difference between the mean squared errors of the exact and approximate estimates of the intensity function. Real failure data are used to illustrate the difference between the exact and approximate estimates of the intensity function.     

Nuclear Magnetic Resonance Studies of Silicon Carbide Polytypes

The ²⁹Si MAS NMR spectra of the 2H, 4H, 6H, and 3C polytypes of silicon carbide are presented. An attempt is made to correlate differences in the chemical shifts with local atomic environment. The results of the analysis of the spectra of pure polytypes are used as a basic for the interpretation of the spectra of mixed polytypes and a discussion of the crystallinity and impurity levels of different samples. Carbon-13 chemical shifts obtained from spectra of the same polytypes are also tabulated.     

Rapid assessment of infant predictors of adult IQ: Midtwin-midparent analyses.

Assessed infant predictors of adult IQ with same-sex infant twins (114 pairs) and their parents. The midtwin–midparent design permits the rapid assessment of infant measures to predict later behavior, because the midparent score serves as a proxy for the infant's potential score at maturity. At 5, 7, and 9 mo, Ss were observed on the Fagan Test of Infant Intelligence, hand preference, vocalizations, selected Bayley Scales of Infant Development items, and a modified Bayley Infant Behavior Record. At 8 mo, Ss received the Visual Expectation Paradigm and an auditory discrimination task. Their parents received the Wechsler Adult Intelligence Scale—Revised (WAIS—R). Some infant measures, indicative of information processing, language ability, and temperament, predicted midparent IQ. This study extended and partially replicated findings from a previous midtwin–midparent cohort (L. F. DiLalla et al; see record 1991-04066-001). (PsycINFO Database Record (c) 2010 APA, all rights reserved)