Processing aspects in the low-frequency noise of nMOSFETs on strained-silicon substrates

The impact of different processing factors on the low-frequency (LF) noise of nMOSFETs fabricated in strained-silicon (SSi) substrates will be described. It is shown that the use of an SSi substrate can yield improved LF noise performance compared with standard Czochralski silicon material. This is demonstrated for both full-wafer and selective epitaxial SSi material. The lower 1/f noise points to an improved gate oxide quality, i.e., with a lower interface and bulk defect density, and is correlated with the low-field mobility or transconductance of the transistors. At the same time, it will be demonstrated that there exist defect-related LF noise mechanisms, which generally give rise to excess generation-recombination (GR) noise. Associated with this GR noise, a degradation of either the OFF-state leakage current or the mobility (transconductance) of the devices is observed. It is clear that noise is a sensitive parameter to local defectiveness and may be a useful tool for both materials' characterization and the analysis of processing-related device degradation mechanisms.     

Applications of natural gas tracers in the detection of reservoir compartmentalisation and production monitoring

This paper describes the application of stable carbon isotope ratios as natural tracers in hydrocarbon reservoirs. Detailed mapping of hydrocarbon composition from closely spaced mud gas samples taken during drilling of horizontal production wells allows for the identification of reservoir compartmentalisation. This applies to reservoirs where fluid heterogeneities exist as a result of filling history or post accumulation hydrocarbon alteration. Case examples assessing fault seal properties are provided. An additional application of the methodology presented is in the detection of subtle spatial variations in reservoir rock quality that may have an influence on fluid flow within the reservoir.In several cases where fluid heterogeneities were detected in horizontal wells, subsequent time-lapse sampling of produced gas and stable carbon isotope measurements of these samples gave means for production allocation. The identification of lost production permitted the identification of an infill well target, and resulted in increased oil recovery by the drilling of a new production well.The use of gas isotopes in the evaluation of reservoir fluid heterogeneities and as natural tracers in the monitoring of reservoir fluids has proved useful in the understanding of reservoir connectivity and fluid flow. The work processes described give valuable insights and help improve reservoir management.     

Panic Disorder and Suicide Attempt in the National Comorbidity Survey.

Clinical and some epidemiological data conflict concerning the likelihood of suicide attempt in individuals with panic disorder (PD). The purpose of this study was to illuminate the panic disorder-suicide attempt association in the National Comorbidity Survey (NCS; R. C. Kessler et al., 1994). Specifically, suicide attempt histories of those 5,872 respondents answering "yes" or "no" to the suicide attempt question were regressed against lifetime diagnostic histories. Lifetime PD history, in the presence of other disorders, was unrelated to elevated risk of suicide attempt and did not account for additional variance. PD respondents who had made a suicide attempt were characterized by Comorbidity. Epidemiological respondents with lifetime histories of PD alone are not at heightened risk for self-reported suicide attempt. (PsycINFO Database Record (c) 2010 APA, all rights reserved)