Importance of the choice of the profile model for ap-n junction in the location of deep levels

The energy levels introduced by Pt in silicon have been measured in a non-abruptp ⁺-n junction using constant-capacitance thermal-emission rate measurements and a numerical simulation of high frequency-capacitance. Two levels have been detected with activation energies of:E _c -E _T = 0.22 eV with acceptor character andE _T -E _v = 0.34 eV with donor character. The sample preparation and diffusion of Pt is similar to previous works in which an acceptor levelE _c -E _T = 0.34 eV was found instead of or besides a donorlike levelE _T -E _v = 0.34 eV. Our numerical calculation of the shallow-impurity profile points to the existence of a gradual transition near the metallurgical junction for these samples. We have demonstrated that the well-known model of an abrupt junction is not appropriate for these types of junctions, and could lead to errors in the location attributed to the detected levels. Simulation of the electrical behavior leads to the non-existence of the acceptor levelE _c −E _T = 0.34 eV located in then-side of the junction.     

A Switched Opamp-Based Bandpass Filter: Design and Implementation in a 0.35 μm CMOS Technology

A fully differential SC bandpass filter (central frequency, 58 kHz; Q = 15; and voltage gain, 8) based on the switched-opamp approach is designed and implemented in this work. The filter operates from a single 1 V supply voltage and is realized in a 0.35 m CMOS technology. It has been characterized with a sampling frequency of 1 MHz and its power consumption is about 230 W. As a main internal filter component, an appropiate switched opamp was also designed. Its common-mode feedback circuit was implemented by using an error amplifier and sampling of the output common-mode voltage is carried out by applying a DC offset to level shift the common-mode sample. It provides an accurate common-mode output for a wide temperature and supply voltage ranges.     

Site Management of Work-in-Process Buffers to Enhance Project Performance Using the Reliable Commitment Model: Case Study

Buffers have been commonly used as a production strategy to protect construction processes from the negative impact of variability. Construction practitioners and researchers have proposed several buffering approaches for different production situations and contexts. However, these solutions have been impractical for managing buffers. To overcome this, this study proposes a new site methodology for managing work-in-process (WIP) buffer in repetitive projects, on the basis of the reliable commitment model (RCM). RCM is a decision-making tool based on lean principles, which uses statistical models to develop more reliable work plans at the operational level. RCM helps to manage WIP buffer in work plans by using site information and planning reliability indicators that result in improved project performance, such as labor productivity and process progress. A repetitive building project was used as a case study. The main finding was that labor productivity, process progress, and waiting times improved when using larger WIP buffers than those typically used among crews. This shows the potential of RCM as a practical tool to manage WIP buffer sizes and to promote the use of lean production strategies at the operational level.     

Comparative antagonism of kainate-activated kainate and AMPA receptors in hippocampal neurons

Native kainate receptors expressed by cultured hippocampal cells were studied in the whole-cell configuration of the patch-clamp technique by using a fast perfusion system. About 80% of the neurons expressed kainate receptors independently of the time in culture (0-4 days), which coincided with the number of cells immunoreactive for a monoclonal antibody against the GluR5/6/7 subunits. Three types of cells were considered: neurons in which the rapid application of kainate induced a rapidly desensitizing current, cells in which kainate induced a more slowly rising, non-desensitizing, response and those in which a mixture of both responses was apparent. Steady responses induced by 300 microM kainate were inhibited by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) in a dose-dependent manner (IC50 = 0.92 microM). CNQX was less potent in blocking transient kainate-induced responses (IC50 = 6.1 microM). Responses to kainate, whether steady or transient, were also inhibited by NS102, showing poor selectivity for the transient response (IC50 = 4.1 and 2.2 microM respectively). The new alpha-amino-3-hydroxy-5-methyl-4-isoxazole (AMPA) receptor antagonist NS394 was very potent in inhibiting steady kainate-induced currents (IC50 = 0.45 microM), but was even more effective in preventing peak responses (IC50 = 0.13 microM). In contrast, cyclothiazide did not affect transient kainate-induced responses but did potentiate current induced by activation of AMPA receptors by AMPA or kainate. These results demonstrate the lack of complete selectivity amongst some available competitive antagonists for AMPA and kainate receptors, and indicate that kainate receptors expressed by hippocampal cells lack the cyclothiazide modulatory site present at AMPA receptors. In addition, the present data support the idea that low-affinity kainate binding sites in the brain correspond to receptor channels selectively activated by kainate.     

A study of Light's criteria and possible modifications for distinguishing exudative from transudative pleural effusions

STUDY OBJECTIVE: To determine the usefulness of modifying Light's criteria for the separation of pleural transudates from exudates. DESIGN: Retrospective review of patients who underwent a diagnostic thoracentesis during a 2-year period. SETTING: Community teaching hospital in Lleida, Spain. PATIENTS AND METHODS: Clinical records and pleural fluid characteristics of 230 consecutive patients with pleural effusion underwent a detailed review. Thirty-five of these patients were excluded from the analysis. As suggested recently by Romero et al, different cutoff levels for the criteria of Light et al were applied and their accuracies were calculated. RESULTS: Thirty-nine (20%) pleural effusions were transudates and 156 (80%) were exudates. The accuracy of the criteria of Light et al for identifying exudates was 94.7% (confidence interval, 91.6 to 97.9) in comparison to our own modified criteria (93.1%; confidence interval, 89.5 to 96.7) and the criteria suggested by Romero et al (92.6%; confidence interval, 88.9 to 96.3). These differences were not statistically significant. CONCLUSION: Changing the classic Light's criteria with different cutoff points offers no advantages for discriminating between transudative and exudative pleural effusions.     

Bedload Transport in Alluvial Channels

Hydraulic, sediment, land-use, and rock-erosivity data of 22 alluvial streams were used to evaluate conditions of bedload transport and the performance of selected bedload-transport equations. Transport categories of transport-limited (TL), partially transport-limited (PTL), and supply-limited (SL) were identified by a semiquantitative approach that considers hydraulic constraints on sediment movement and the processes that control sediment availability at the basin scale. Equations by Parker et al. in 1982, Schoklitsch in 1962, and Meyer-Peter and Muller in 1948 adequately predicted sediment transport in channels with TL condition, whereas the equations of Bagnold in 1980, and Schoklitsch, in 1962, performed well for PTL and SL conditions. Overall, the equation of Schoklitsch predicted well the measured bedload data for eight of 22 streams, and the Bagnold equation predicted the measured data in seven streams.     

Perfluorocarbons are effective oxygen carriers in cardiopulmonary bypass

Intravascular perfluorochemical (PFC) emulsions together with a high oxygen (O2) tension may increase the delivery of dissolved O2 to useful levels. A severely anemic model of cardiopulmonary bypass (CPB) was used to test the hypothesis that a novel PFC emulsion (PFCE; Oxygent [Alliance Pharmaceutical Corp., San Diego, CA] 90% w/v perflubron) used at a high PO2 during bypass delivers sufficient O2 to ameliorate hypoxic myocardial contractile dysfunction. Acutely anemic dogs (N = 42; hematocrit = 15.8 +/- 0.6% [mean +/- SEM] before CPB and 10.9 +/- 0.1% during CPB) were divided into four groups. Group 1 was a control (n = 12). As CPB was initiated, groups 2 (n = 10), 3 (n = 10), and 4 (n = 10) had 1.35 g PFC.kg-1, 2.7 g PFC.kg-1, or 5.4 g PFC.kg-1 added via the venous return cannula. Pre-CPB and post-CPB cardiac function was measured by the first derivative of left ventricular pressure (dP/dtmax). The dP/dtmax on separation from CPB was: group 1, 619 +/- 96; group 2, 738 +/- 56; group 3, 782 +/- 101; and group 4, 828 +/- 100 (p < 0.05 groups 3 and 4 versus group 1). Mortality during the first hour after separation from CPB was higher in group 1 than in PFCE treated dogs; however, this trend did not attain statistical significance (p < 0.065). The PFC dose was higher in survivors than in nonsurvivors (2.6 +/- 0.4 g PFC.kg-1 versus 1.2 +/- 0.5 g PFC.kg-1; p < 0.05). A PFCE used at a high PO2 provides sufficient physically dissolved O2 to relieve myocardial hypoxic injury in a severely anemic model of CPB. Current PFCEs are effective O2 carriers. This finding suggests that they can be used as a temporary erythrocyte substitute to diminish the need for allogeneic transfusions during cardiac operations.     

Synthesis method for testable electrical networks using 1st order building blocks

This work presents a method for synthesizing testable continuous-time linear time-invariant electrical networks using 1st order blocks for the implementation of analog linear circuits. A functional-structural fault model for the block, and a fault dictionary are proposed together with a simple set of test vectors. The method allows, also, the fault grade evaluation for the modeled faults. The results obtained from the two application examples have shown the suitability of the approach as a design for test method for analog circuits.