Detection of trace water vapor in high-purity phosphine using cavity ring-down spectroscopy

The presence of trace water vapor in process gases such as phosphine, used for compound semiconductor epitaxial growth, can negatively affect the optical and electrical properties of the final device. Therefore, sensitive H2O measurement techniques are required to monitor precursor purity and detect unacceptable contamination levels. A commercial cavity ring-down spectrometer that monitors an H2O absorption line at a wavelength of 1392.53 nm was investigated for service in high purity PH3. Spectral parameters such as the line shape of water vapor in the presence of PH3 as well as background features due to PH3 were measured at different pressures and incorporated into the data analysis software for accurate moisture readings. Test concentrations generated with a diffusion vialbased H2O source and dilution manifold were used to verify instrument accuracy, sensitivity, linearity, and response time. H2O readings at 13.2 kPa corresponded well to added concentrations (slope=0.990+/-0.01) and were linear in the tested range (0-52.7 nmol mol-1). The analyzer was sensitive to changes in H2O concentration of 1.3 nmol mol-1 based on 3sigma of the calibration curve intercept for a weighted linear fit. Local PH3 absorption features that could not be distinguished from the H2O line were present in the purified PH3 spectra and resulted in an additional systematic uncertainty of 9.0 nmol mol-1. Equilibration to changing H2O levels at a flow rate of 80 std cm3 min-1 PH3 occurred in 10-30 minutes. The results indicate that cavity ring-down spectroscopy (CRDS) at 1392.53 nm may be useful for applications such as on-line monitoring (and dry-down) of phosphine gas delivery lines or the quality control of cylinder sources.     

Does attention capacity moderate the effect of driver distraction in older drivers?

With age, a decline in attention capacity may occur and this may impact driving performance especially while distracted. Although the effect of distraction on driving performance of older drivers has been investigated, the moderating effect of attention capacity on driving performance during distraction has not been investigated yet. Therefore, the aim was to investigate whether attention capacity has a moderating effect on older drivers’ driving performance during visual distraction (experiment 1) and cognitive distraction (experiment 2). In a fixed-based driving simulator, older drivers completed a driving task without and with visual distraction (experiment 1, N = 17, mean age 78 years) or cognitive distraction (experiment 2, N = 35, mean age 76 years). Several specific driving measures of varying complexity (i.e., speed, lane keeping, following distance, braking behavior, and crashes) were investigated. In addition to these objective driving measures, subjective measures of workload and driving performance were also included. In experiment 1, crash occurrence increased with visual distraction and was negatively related to attention capacity. In experiment 2, complete stops at stop signs decreased, initiation of braking at pedestrian crossings was later, and crash occurrence increased with cognitive distraction. Interestingly, for a measure of lane keeping (i.e., standard deviation of lateral lane position (SDLP)), effects of both types of distraction were moderated by attention capacity. Despite the decrease of driving performance with distraction, participants estimated their driving performance during distraction as good. These results imply that attention capacity is important for driving. Driver assessment and training programs might therefore focus on attention capacity. Nonetheless, it is crucial to eliminate driver distraction as much as possible given the deterioration of performance on several driving measures in those with low and high attention capacity.     

High-velocity transport of nanoparticles through 1-D nanochannels at very large particle to channel diameter ratios

We explore the possibility of generating high-velocity flows of nanoparticles through flat-rectangular nanochannels, which are only 50% deeper than the diameter of the particles. Using the shear-driven flow principle, 200-nm particles can, for example, be transported through a 300-nm-deep channel at velocities up to 35 mm/s (upper limit of our current setup). Working under high-pH conditions, the velocity of the carboxylated nanoparticles still respects the small-molecule velocity law, despite the high degree of confinement to which the particles are subjected. The high degree of confinement is also found to lead to a reduced band broadening. When injecting sharply delimited particle plugs, the plate heights observed for the flow of 0.2-microm particles through a 0.3-microm channel (with plate heights of the order of 1-2 microm) are, for example, approximately 1 order of magnitude smaller than for the flow of 1.0-microm particles through a 1.4-microm channel. It is also found that the band broadening is, within its statistical variation, independent of the fluid velocity over a large range of particle velocities (5-35 mm/s). The flow method distinguishes itself from pressure-driven field-flow fractionation and hydrodynamic chromatography in that the mean particle velocity is independent of the particle size over the entire range of possible particle to channel diameter ratios.     

Modeling prostate anatomy from multiple view TRUS images for image-guided HIFU therapy

Current planning methods for transrectal high-intensity focused ultrasound treatment of prostate cancer rely on manually defining treatment regions in 15-20 sector transrectal ultrasound (TRUS) images of the prostate. Although effective, it is desirable to reduce user interaction time by identifying functionally related anatomic structures (segmenting), then automatically laying out treatment sites using these structures as a guide. Accordingly, a method has been developed to effectively generate solid three-dimensional (3-D) models of the prostate, urethra, and rectal wall from boundary trace data. Modeling the urethra and rectal wall are straightforward, but modeling the prostate is more difficult and has received much attention in the literature. New results presented here are aimed at overcoming many of the limitations of previous approaches to modeling the prostate while using boundary traces obtained via manual tracing in as few as 5 sector and 3 linear images. The results presented here are based on a new type of surface, the Fourier ellipsoid, and the use of sector and linear TRUS images. Tissue-specific 3-D models will ultimately permit finer control of energy deposition and more selective destruction of cancerous regions while sparing critical neighboring structures.     

DNA microarray enhancement using a continuously and discontinuously rotating microchamber

It is demonstrated that the most efficient way to enhance DNA microarray analysis consists of a maximal reduction of the total device volume (to keep the concentration of the available DNA as high as possible), combined with the creation of a strong lateral convective transport of the sample. In the present study, DNA microarray hybridizations are performed in a set of rotating, circular microchambers covering exactly the spotted area of the microarray and with a depth varying between 70 and 1.6 microm. Rotating the microchamber substrate while keeping the microarray stationary, the rotating microchamber bottom wall literally drags the sample past the microarray spots with a velocity which is independent of the fluid layer thickness. Interestingly, it was found that transporting the sample in a discontinuous mode (with stop periods of several minutes) not only yields a more stable and reproducible operation, it also yields significantly larger hybridization intensities (typically a factor of 2-3 larger) than a continuous rotation. This seems to be due to the fact that the velocity field disturbs the binding process at the binding site level. Working under limiting DNA sample mass conditions, the system yielded in a short, 30-min experiment already a 5-fold increase of the hybridization intensity, as compared to a conventional microscope slide/coverslip system operated overnight under diffusion-driven conditions. Compared to a commercial pump-around hybridization system, the gain was even more impressive, precisely due to the fact that the pump-around system requires larger volumes, which with a fixed amount of available genetic material leads to the application of more diluted samples.     

Engineer’s Study Notes for Understanding the Arbitration Process

Using arbitration to resolve commercial disputes has many advantages over court-based litigation. These include the use of “judges” who understand the relevant technical issues and industry practices and thus reduce the probability of unpredictable results can significantly reduce the cost and delay associated with document exchange and depositions and can reduce the amount of time spent on evidence presentation in hearings. Engineers can play an important role when determining whether their organizations and their clients arbitrate or litigate. The use of arbitration requires contractual agreement. Without the inclusion of predispute arbitration procedures in the project’s contracts, it is likely that disputes will be resolved through litigation and not arbitration. Engineers can influence the inclusion of arbitration because they often suggest the forms of project contracts as representatives of engineering, contracting, or owner organizations. Engineers may also find themselves in management roles where they will be involved in a dispute that will be resolved via arbitration. As a party to the arbitration, it is important for the engineer to understand what influence he or she has in making decisions regarding the arbitration process. This paper provides guidance to engineers who are in a position to influence the inclusion of arbitration in the project contracts. This paper also provides suggestions about how the engineer can work with the attorneys to influence the best and most cost- and time-efficient result in the event an arbitration has been commenced. This paper is not a theoretical research paper but rather is a practical guideline based on the experience of the writers, who are engineers and who have been in the arbitration field, both domestically and internationally for over 30?years, seeing the good, the bad, and the ugly. Together, they share their insights on why the arbitration process can be the better choice for dispute resolution.     

An empirical assessment of the form of utility functions.

Utility functions, which relate subjective value to physical attributes of experience, are fundamental to most decision theories. Seven experiments were conducted to test predictions of the most widely assumed mathematical forms of utility (power, log, and negative exponential), and a function proposed by Rachlin (1992). For pairs of gambles for real monetary gains, undergraduate and nonstudent subjects either reported an equalizing amount for 1 outcome that made the gambles subjectively equal or chose between gambles where the amounts were varied across trial, which allowed the equalizing amount to be estimated from their pattern of choices. Using a novel method that eliminates several limitations of previous research, I manipulated the outcomes across trials such that each type of utility function predicted a linear relationship between the equalizing amounts and the amounts of the other outcomes, and made point predictions for either the slope or intercept of that relationship. In a meta-analysis across experiments, systematic departures from the point predictions were observed for each type of utility function. Thus, the data imply that despite their historical importance and incorporation in many psychological and economic decision theories, the most widely assumed models of utility are incorrect. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Homosexuality and psychopolitics: An historical overview.

Traces various sources of attitudes toward homosexuality (HMSX) throughout history and explores the scientific and political forces that contributed to the depathologization of HMSX in the psychological community via the American Psychological Association. Advances in the understanding of lesbian and gay issues within psychology since the early 1970s are considered, as well as an analysis of the current state of attitudes toward HMSX within professional psychology. Attitudes toward HMSX within psychology have changed from viewing HMSX as a form of mental illness to considering gay males and lesbians to be an oppressed group in need of special considerations. However, more attention needs to be paid to the diversity within the lesbian and gay male populations in terms of race and ethnicity, religious diversity, class issues, and physical, emotional, and cognitive disability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

SQL Server Integration Services 2005中的模糊查找和模糊分组

简介 由于拼写错误、意外的缩略语和其他不规则问题，实际的数据是“有问题”的。因此，在数据仓储项目中，很大一部分的时间和金钱都花费在了数据提取、数据转换和数据加载（ETL，Extraction、Transformation、Loading）阶段。在ETL阶段，新数据被清理、标准化，并使其与现有数据一致。在Microsoft SQL Server 2005中可用的模糊查找和模糊分组转换，有助于使ETL过程在遇到若干种在交际数据中观测到的常见错误时更易复原。它们解决一般的匹配和分组问题，而无需特定于域的规则和脚本的专家集合。通过为您的域自定义模糊查找和模糊分组，您可以利用Business Intelligence Development Studio内的通用数据清理算法，并避免创建复杂的自定义规则和代码。