A Comparison of Reliability Growth Models

A reliability growth model is an analytic tool that accounts for changes in reliability due to design modifications and other corrective actions taken during the develpment, production, and use of a new piece of equipment. This paper describes a simulation study, and its conclusions, comparing four general reliability growth models that have been proposed in the reliability literature. Details of the simulation results are available in a separate Supplement.     

高速水流喷射冲击点焊——在太空中实现薄板冲击点焊的装置

在太空中的焊接有可能成为修复太阳能电池板的好方法。本文介绍一种用水流(或其它液体)喷射冲击点焊的方法。采用这种方法可以得到具有高强度的环形焊接区。为了产生高速流体喷射,设计、制造了一套尺寸较小的专用系统。这样就使得利用流体喷射冲击实现在太空中焊接薄板的设想成为可能。     

A relationship between leader intelligence and leader rated effectiveness.

Conceptualizes intelligence as the leader's ability to integrate his experience and thus provide him with skills to deal effectively with the technical aspects of tasks and interpersonal relationships. In 4 studies, 55 sergeants in charge of field artillery sections, 55 navy petty officers, 58 unit commanders, and 52 sergeants in charge of army mess units completed the least preferred co-worker scale (LPC), a group atmosphere scale, a shortened version of the Henmon-Nelson Tests of Mental Ability, and ratings of situational favorableness on 3 dimensions (leader-member relations, task structure, and position power). Ratings of leader performance were completed by 2-3 superiors. Results indicate that the relationship between leader intelligence and performance depended on the leader's motivational style (LPC), his experience, and the leader-member relations. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of three techniques used to measure diffusive gas exchange from sheltered aquatic surfaces

Three approaches commonly used to quantify diffusive gas exchange across aquatic surfaces were compared in a densely treed, low-wind environment Diffusive surface fluxes of carbon dioxide (CO2) and methane (CH4) from a small boreal reservoir were estimated using (i) surface water concentrations, the thin boundary layer (TBL) equation, and gas transfer velocities (k) calculated using sulfur hexafluoride (SF6); (ii) surface water concentrations, the TBL equation, and k estimated from wind speed; and (iii) static floating chambers (FCs). Comparisons were made during three different approximately 10-day intervals (August 2000, June and September 2001). CO2 and CH4 fluxes estimated from SF6-derived k were on average 1-3 times greater than those determined from wind-estimated k Overall agreement between FC CO2 and CH4 flux estimates and those based on SF6 and wind speed derived kvalues was much weaker, with FC CO2 and CH4 flux estimates ranging from -9 to 23 times those based on SF6 and wind-estimated k values. Chamber deployment likely enhanced gas transfer through disturbance of the surface boundary layer, and results of this study suggest that caution must be exercised concerning the use of FCs on very still water surfaces. Furthermore, findings of this study contradict the common belief that use of wind speed to approximate k is inappropriate for small bodies of water characterized by low winds and surface obstructions.     

Quantitative characterization of the microstructure of two-phase TiB<Subscript>2</Subscript>+Al<Subscript>2</Subscript>O<Subscript>3</Subscript> ceramics using mean integral curvature

Two-phase TiB₂+Al₂O₃ ceramics with an interconnected or dispersed TiB₂ (minor)-phase microstructure can be produced by variations in processing parameters. A standard method of quantitative characterization of the microstructural bias, i.e., the degree of TiB₂ phase connectivity relative to its dispersion, is necessary to comprehend the mechanism(s) controlling the evolution of microstructure during processing. In this work, techniques derived from stereology were used to quantitatively characterize the microstructural bias on the basis of the connectivity and dispersion of the minor phase (TiB₂), in addition to the size of the TiB₂- and Al₂O₃-phase regions. The mean integral curvature calculated using the area particle-count and area tangent-count methods was determined to quantitatively describe the connectivity of the TiB₂ minor phase around the Al₂O₃ major phase. The results illustrate that, in spite of partial and mixed bias, integral curvature measurements (particularly those based on the area tangent-count method) provide a reliable and reproducible means for quantitative characterization of the two-phase biased microstructure.     

Characterization and quantitation of aprepitant drug substance polymorphs by attenuated total reflectance fourier transform infrared spectroscopy

In this study, we report the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT-IR) for the identification and quantitation of two polymorphs of Aprepitant, a substance P antagonist for chemotherapy-induced emesis. Mixtures of the polymorph pair were prepared by weight and ATR-FT-IR spectra of the powdered samples were obtained over the wavelength range of 700-1500 cm(-1). Significant spectral differences between the two polymorphs at 1140 cm(-1) show that ATR-FT-IR can provide definitive identification of the polymorphs. To investigate the feasibility of ATR-FT-IR for quantitation of polymorphic forms of Aprepitant, a calibration plot was constructed with known mixtures of the two polymorphs by plotting the peak ratio of the second derivative of absorbance spectra against the weight percent of form II in the polymorphic mixture. Using this novel approach, 3 wt % of one crystal form could be detected in mixtures of the two polymorphs. The accuracy of ATR-FT-IR in determining polymorph purity of the drug substance was tested by comparing the results with those obtained by X-ray powder diffractometry (XRPD). Indeed, polymorphic purity results obtained by ATR-FT-IR were found to be in good agreement with the predictions made by XRPD and compared favorably with actual values in the known mixtures. The present study clearly demonstrates the potential of ATR-FT-IR as a quick, easy, and inexpensive alternative to XRPD for the determination of polymorphic identity and purity of solid drug substances. The technique is ideally suited for polymorph analysis, because it is precise, accurate, and requires minimal sample preparation.     

Functionalized silicon membranes for selective bio-organism capture

Membranes with various pore size, length, morphology and density have been synthesized from diverse materials for size-exclusion-based separation. An example is the sterilization of intravenous lines by exclusion of bacteria and viruses using polyvinylidene fluoride membranes with 0.1-microm-diameter pores. Chemically specific filtration has recently been addressed for small molecules. Nevertheless, specific bio-organism immobilization and detection remains a great technical challenge in many biomedical applications, such as decontamination or analysis of air and liquids such as drinking water and body fluids. To achieve this goal, materials with controlled pore diameter, length and surface chemistry are required. In this letter, we present the first functionalized silicon membranes and demonstrate their ability to selectively capture simulated bio-organisms. These extremely versatile and rigid devices open the door to a new class of materials that are able to recognize the external fingerprints of bio-organisms-such as size and outer membrane proteins-for specific capture and detection applications.     

Guest editors' introduction.

The idea, or seed for this special series on psychotherapy training originally grew from a panel that took place at the 2006 North American Society of Psychotherapy Research (NASPR) conference in Burr Oak, Ohio. Although adhering to different theoretical perspectives and representing diverse professional backgrounds, the contributors to this panel (the authors in this series) agreed that little more than a dearth of research has been conducted on psychotherapy training. This knowledge gap, to a certain degree, mimics the current status of psychotherapy research. Given that we know that psychotherapy works, it seems reasonable to conclude that something is working in the training of psychotherapists. We are, however, less confident in our ability to explain how psychotherapy works, and, similarly, we are less knowledgeable about what are the most effective (and ineffective) elements of training. In our view, just as we pursue the question of how psychotherapy works in the hope of improving treatment outcomes, we should also pursue a greater knowledge base regarding psychotherapy training in the hope of improving training programs, and ultimately treatment outcomes. One goal of this series is to offer a variety of perspectives on effective psychotherapy training based on empirical knowledge, theory, and clinic experience. Another important goal of this series is to provide directives for future research on training, in the hope of providing a framework from which to begin addressing the aforementioned gap in the field's knowledge base. Thus, each of the four following papers is comprised of two parts: one addressing important elements of a training program and another that is focused on future directions for research on training. In addition to the common structure of the papers in this series, we believe that each paper plays a complimentary role in relation to the others. Although the authors of this series agree on the importance of training, they all believe that much more needs to be done to better understand and foster the development of effective therapists. As such, our hope in putting together this series was to encourage the field to actively pursue better ways to think about and conduct psychotherapy training, as well as to devote more energy in research aimed at addressing some of the critical questions raised by this complex endeavor. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of reliability and metallurgical integrity of wire bonds and lead free solder joints on flexible printed circuit board sample modules

This paper presents a study of the optimization of the gold plating thickness for the use of both wire bonding and soldered interconnects on a flexible printed circuit board sample module. Wire bondability is typically better, when the gold plating thickness is greater than 30 μin.; however, the risk of problems with solder joint embrittlement becomes a concern with thick gold plating. In order to better understand the effect of the gold plating thickness on wire bondability and solder joint embrittlement, an evaluation was performed on samples with three ranges of gold plating thicknesses (10–20 μin., 20–30 μin., and 30–45 μin.), on flexible printed circuit board (PCB), substrates. Mechanical shear testing and metallurgical analyses were conducted on chip component solder joints in this three thickness gold study. Thermal shock and drop testing were conducted to evaluate the reliability of the sample modules. Drop testing is especially critical for determining the reliability of the sample modules, which are used in portable consumer electronics products. Reliability testing and metallurgical analyses have been performed to characterize the effect of gold embrittlement on the mechanical integrity of the solder joints with a gold content ranging from 1 to 4 wt.%.