Noninterfering optical method of HBT circuit evaluation

The authors report a novel noninterfering and simple approach for evaluation of circuits implemented with AlGaAs/GaAs heterojunction bipolar transistors (HBTs). This method makes use of radiative recombination in the base region of current-carrying HBTs. The infrared radiation emitted is 'visible' to the closed-circuit TV (CCTV) cameras. Therefore, one can view the operation of the HBT circuit under test at normal biases with a TV monitor. This method can be used to determine logic states of gates, as well as collector current of individual HBTs within integrated circuits.<>     

Frictional assessment of magnesium stearate and palmitate lubricant powders

A method has been developed for the frictional assessment of powder lubricants using a shear-box tester similar to that employed by Jenike. One commercial magnesium stearate, three high-purity magnesium stearates and three high-purity magnesium palmitates were assessed using this method. Powders with a well-ordered crystal structure and particle shape have a lower initial maximum coefficient of friction μ_a. The difference between μ_a and μ_b, the equilibrium dynamic friction coefficient, gives an indication of lubricant film-forming propensity. The basic friction equation is obeyed by the powders for most of the load range studied but deviates slightly approaching zero normal load.     

High-speed, polyimide-based semi-insulating planar buried heterostructures

We describe planar buried heterostructure lasers which have low capacitance (lpF), large bandwidth (19GHz), high power (>20mW/facet) and high temperature operation (100°C). These lasers are very suitable for long-distance, highspeed digital and analogue signal transmission.     

Determining pheromone content of hairpencils from individual virgin males ofPseudaletia unipuncta (Haw.) (Lepidoptera: Noctuidae)

Levels of benzaldehyde recovered from virginPseudaletia unipuncta (Haw.) males were not influenced by (1) the time hairpencils remained in the solvent (1-72 hr), (2) anesthetization or agitation of males prior to excision of hairpencils, or (3) the time (photophase or scotophase) that hairpencils were excised. Thus the interindividual variability observed is not a methodological artifact. Most males had similar concentrations in both hairpencils, although in some cases only one hairpencil contained pheromone. In one case, a male with partially extruded hairpencils had no benzaldehyde at all. Neither pupal weight nor hairpencil length proved to be reliable indicators of pheromone content.Contribution No. 373, Département de biologie, Université Laval.     

印度水电方面的技术成就

大型水电工程需要大量的开挖隧洞，作者是负责印度国家水电公司（NHPC）所属的Tessta Ⅱ级水电工程的总工程师，现对印度在水电开发中的最新隧洞开挖工程做了一个展望。     

The pathogenesis of undiagnosed peritonitis in middle-aged and elderly patients with acute coronary insufficiency

Three-stage treatment using a day hospital instead of a sanatorium with regards to the pattern of a tuberculosis process can achieve the results of closure of decay and abacillation cavities, which are not inferior to those with the conventional treatment, by reducing the basic regimen through the length of a hospital stage. The efficiency of two-stage treatment (day hospital--outpatient clinic) of lung tissue decay and culture-positive patients depends on the duration of the basic regimen, patient compliance, and the presence of a concomitant abnormality.     

Relationship of seizure duration to antidepressant efficacy in electroconvulsive therapy

BACKGROUND: Aprotinin and epsilon-aminocaproic acid are routinely used to reduce bleeding during cardiac surgery. The marked difference in average wholesale cost between these two drug therapies (aprotinin, $1,080 vs. epsilon-aminocaproic acid, $11) has generated significant controversy regarding their relative efficacies and costs. METHODS: In a multicenter, randomized, prospective, blinded trial, patients having repeated cardiac surgery received either a high-dose regimen of aprotinin (total dose, 6 x 10(6) kallikrein inactivator units) or epsilon-aminocaproic acid (total dose, 270 mg/kg). RESULTS: Two hundred four patients were studied. Overall (data are median [25th-75th percentiles]), aprotinin-treated patients had less postoperative thoracic drainage (511 ml [383-805 ml] vs. 655 ml [464-1,045 ml]; P = 0.016) and received fewer platelet transfusions (0 [range, 0-1] vs. 1 [range, 0-2]; P = 0.036). The surgical field was more likely to be considered free of bleeding in aprotinin-treated patients (44% vs. 26%; P = 0.012). No differences, however, were seen in allogeneic erythrocyte transfusions or in the time required for chest closure. Overall, direct and indirect bleeding-related costs were greater in aprotinin- than in epsilon-aminocaproic acid-treated patients ($1,813 [$1,476-2,605] vs. $1,088 [range, $511-2,057]; P = 0.0001). This difference in cost per case varied in magnitude among sites but not in direction. CONCLUSIONS: Aprotinin was more effective than epsilon-aminocaproic acid at decreasing bleeding and platelet transfusions. Epsilon-aminocaproic acid, however, was the more cost-effective therapy over a broad range of estimates for bleeding-related costs in patients undergoing repeated cardiac surgery. A cost-benefit analysis using the lower cost of half-dose aprotinin ($540) still resulted in a significant cost advantage using epsilon-aminocaproic therapy (P = 0.022).     

Association between cigarette smoking and lipid peroxidation in a controlled feeding study

BACKGROUND: Cigarette smoke may promote atherogenesis by producing oxygen-derived free radicals that damage lipids. However, evidence in support of this hypothesis is inconsistent because most studies did not control for aspects of diet (antioxidants and lipid substrate) that may confound the association between smoking and measures of lipid peroxidation. METHODS AND RESULTS: The relationships between cigarette smoking and two measures of lipid peroxidation, breath ethane (an in vivo assay) and thiobarbituric acid-reactive substances (TBARS, an in vitro assay), were examined in 123 adults (11% of whom were smokers) participating in a controlled feeding study. After 3 weeks of controlled feeding on a common diet (36% total fat, 14% saturated fats, 6% polyunsaturated fats, and 12% monounsaturated fats), breath and fasting serum samples were collected for measurement of ethane and TBARS, respectively. Baseline characteristics of smokers and nonsmokers were similar, including several indices related to diet and nutritional status (albumin, cholesterol, body mass index, and oxygen radical-absorbing capacity). Cigarette smokers had significantly higher breath ethane (8.88 versus 1.71 pmol/L; P<.0001) and TBARS (24.0 versus 20.7 micromol/mL; P=.008) than nonsmokers. The interval between breath collection and the time the last cigarette was smoked was significantly and inversely correlated with breath ethane. Neither measure of lipid peroxidation was associated with measures of serum cholesterol or albumin, body mass index, or serum oxygen radical-absorbing capacity. CONCLUSIONS: Cigarette smokers have higher rates of in vivo and in vitro lipid peroxidation. These results support the hypothesis that the atherogenic effects of smoking are mediated in part by free radical damage to lipids.