Electron drift mobility model for devices based on unstrained andcoherently strained Si1-xGex grown on <001>silicon substrate

The electron drift mobility for unstrained and coherently strained Si_1-xGe_x grown on a <001> silicon substrate is analytically obtained for Ge fractions less than 30%. The method is based on the following two assumptions: the conduction bands of the unstrained alloy are Si-like for Ge fraction less than 30%, and in the case of the coherently strained alloy, strain-induced energy shifts occur in the conduction band valleys. The shifts in energy yield two different mobility values: one corresponding to the growth plane with a value larger than the unstrained mobility, and the other parallel to the growth direction and correspondingly smaller in value. In comparison to silicon, the results show a degradation of both the unstrained mobilities for doping levels up to 10¹⁷ cm^-3. Beyond this doping level, the strained mobility component parallel to the growth direction becomes slightly larger than the mobility of silicon     

Umbilical warts: a new entity?

Two cases of umbilical warts are described. The occurrence of these lesions was not previously known. In both cases there was a history of long-standing genital warts.     

Plasma immersion ion implantation for SOI synthesis: SIMOX and ion-cut

We have demonstrated feasibility to form silicon-on-insulator (SOI) substrates using plasma immersion ion implantation (PIII) for both separation by implantation of oxygen and ion-cut. This high throughput technique can substantially lower the high cost of SOI substrates due to the simpler implanter design as well as ease of maintenance. For separation by plasma implantation of oxygen wafers, secondary ion mass spectrometry analysis and cross-sectional transmission electron micrographs show continuous buried oxide formation under a single-crystal silicon overlayer with sharp Si/SiO₂ interfaces after oxygen plasma implantation and high-temperature (1300°C) annealing. Ion-cut SOI wafer fabrication technique is implemented for the first time using PIII. The hydrogen plasma can be optimized so that only one ion species is dominant in concentration and there are minimal effects by other residual ions on the ion-cut process. The physical mechanism of hydrogen induced silicon surface layer cleavage has been investigated. An ideal gas law model of the microcavity internal pressure combined with a two-dimensional finite element fracture mechanics model is used to approximate the fracture driving force which is sufficient to overcome the silicon fracture resistance.     

A transgenic T cell receptor restores thymocyte differentiation in interleukin-7 receptor alpha chain-deficient mice

Traffic accidents are a well-known public health problem worldwide. In Mexico research into risk factors for motor involving vehicles accidents and their consequences has recently been taken into account. The relevant literature does not normally describe the methodological aspects involved in the collection of primary data, since most studies have used secondary data the good quality and validity of which are assumed. The paper presented seeks to discuss and share with researchers in this field, some of the methodological aspects to be considered in the attempt to recreate the scene of the accident and obtain information approximating to reality. The measurements in situ of, such traffic accident variables as injury, use of seat belt, speed and alcohol intake are discussed.     

Electroencephalogram asymmetry in response to the approach of a stranger and maternal separation in 10-month-old infants.

We recently reported the presence of reliable asymmetries in frontal-brain electrical activity in infants that distinguished between certain positive- and negative-affect elicitors. In order to explore the degree to which these asymmetries in brain activity are associated with individual differences in affective response, 35 ten-month-old female infants were presented with a stranger-approach, mother-approach, and maternal-separation experience while an electroencephalogram (EEG) from the left- and right-frontal and left- and right-parietal scalp regions was recorded and facial and other behavioral responses were videotaped. Changes in frontal-EEG asymmetry reflected behavioral changes between conditions. In addition, individual differences in affective response to separation were related to differences in frontal-brain asymmetries. These findings indicate that lawful changes exist in asymmetries of frontal-brain activation during the expression of certain emotions in the first year of life and that individual differences in emotional responsivity are related to these measures of brain activity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

手持终端设备电源管理系统的PPTC电路保护

着重介绍Raychem电路保护部的PolySwitch PPTC（聚合物正温度系数）元件在电源管理中提供电流过载和温度过载的保护过程。另外还介绍了电源适配器、CLA（点烟器）、移动电话设备及电池板的保护装置是如何进一步改善实际使用中的总体可靠性的。     

The impact of pre-clerking clinics on surgical operation cancellations: a prospective audit

Pre-clerking of all patients undergoing elective general surgical operations was introduced at our hospital in an attempt to reduce an unacceptably high operation cancellation rate. A prospective audit has been performed on the effect of this policy on the cancellation rate. Before the introduction of pre-clerking there was a marked seasonal variation in the number of patients who failed to attend for surgery, which could be explained by absence on holiday. This seasonal variation disappeared after the start of pre-clerking clinics, but there has been no reduction in the number of cancellations for medical reasons.     

Coupled electrothermal modeling of microheaters using SPICE

In this paper,,we report a novel simulation approach that computes both the transient and steady state electrothermal behavior in integrated circuit (IC) compatible thermally isolated microheaters. The resulting distribution of heat, current density and temperature, as well as the electrical terminal behavior have been obtained for realistic device structures. The results are based on a two-dimensional solution of the coupled system of partial differential equations that govern both electrical and heat transport in the device. Unlike standard numerical approaches for coupled systems, our technique is based on the behavioural models, available in most commercial circuit simulators (e.g., HSPICE), that allow synthesis of complex, nonlinear, and coupled circuit elements. The simulation results are in excellent agreement with measurement data of steady state and transient terminal characteristics, obtained under conditions of vacuum. We note that this modeling approach allows concurrent simulation (and subsequent optimization) of the performance of both the control electronics as well as the thermal element(s), within the same IC design environment     

Volatile constituents of palm wine and palm sap

Palm wine and pasteurised palm sap volatiles were collected, concentrated on a Tenax GC and analysed by gas chromatography and gas chromatography-mass spectrometry. Eighty-two components were identified: 47 esters, 9 alcohols, 5 acids, 6 carbonyls, 2 acetals, 4 terpenes and 9 hydrocarbons. These had all been found previously in conventional wines. Odour evaluation of the separated palm wine components as they eluted suggested that no one compound is responsible for the characteristic palm wine odour. The acetates of higher alcohols and the ethyl esters of straight-chain aliphatic C₆-C₁₀ acids seemed to be important and may play a big role in imparting the fruity nuances of characteristic palm wine odour. Their association with alcohols seemed also to be necessary for the expression of typical palm wine odour. The qualitative difference between palm sap aroma and palm wine aroma appeared to be due mainly to the presence of these esters and alcohols in palm wine and their apparent absence from palm sap, as well as to the presence of some low-boiling esters and alcohols in palm sap and their apparent absence from palm wine.     

Predicting oxide stability in high-temperature water vapor

The importance of understanding and predicting the interactions of oxides with water vapor at high temperatures is demonstrated in this article. Methods for observing volatilization phenomena and identifying the chemical formulae for volatile metal hydroxides are discussed. In addition, techniques for obtaining accurate thermodynamic data for gaseous metal hydroxide species are described. Detailed examples of the stability of the principle structural and/or protective oxides chromia (Cr₂O₃), silica (SiO₂), and alumina (Al₂O₃) in high-temperature water vapor are included.