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931.
V. P. Evtikhiev I. V. Kudryashov E. Yu. Kotel’nikov V. E. Tokranov A. N. Titkov I. S. Tarasov Zh. I. Alferov 《Semiconductors》1998,32(12):1323-1327
The electroluminescence and stimulated emission of lasers with one layer of InAs quantum dots (QD’s) grown in a single molecular-beam
epitaxial process on vicinal GaAs(001) surfaces misoriented in the direction [010] by 2, 4 and 6° are investigated. It is
discovered that an increase in the misorientation angle leads to a blue shift and a decrease in the full width at half maximum
(FWHM) of the electroluminescence spectrum. This effect is attributed to a decrease in the size of the quantum dots and improvement
in their size uniformity. A strong dependence of the threshold current density on the width of the spontaneous luminescence
spectrum is discovered. The room-temperature threshold current density of the lasers with one layer of quantum dots and the
spontaneous luminescence spectrum having the smallest FWHM (54 meV) equals 210 A/cm2.
Fiz. Tekh. Poluprovodn. 32, 1482–1486 (December 1998) 相似文献
932.
On solving constrained optimization problems with neural networks:a penalty method approach 总被引:7,自引:0,他引:7
Deals with the use of neural networks to solve linear and nonlinear programming problems. The dynamics of these networks are analyzed. In particular, the dynamics of the canonical nonlinear programming circuit are analyzed. The circuit is shown to be a gradient system that seeks to minimize an unconstrained energy function that can be viewed as a penalty method approximation of the original problem. Next, the implementations that correspond to the dynamical canonical nonlinear programming circuit are examined. It is shown that the energy function that the system seeks to minimize is different than that of the canonical circuit, due to the saturation limits of op-amps in the circuit. It is also noted that this difference can cause the circuit to converge to a different state than the dynamical canonical circuit. To remedy this problem, a new circuit implementation is proposed. 相似文献
933.
1. Occupational health nurses need a general knowledge of psychiatric medications to work effectively with clients and their off site health providers. 2. Acquiring an understanding of the major classes of medications--anti-psychotic, anti-anxiety, anti-depressant, and antimanic--is important. 3. It is helpful to understand under what conditions and with which conditions psychotropic medications are helpful. 相似文献
934.
Binder M. Mammone R.J. Wade W.L. Jr. Rondeau E. Lavene B. 《Electrical Insulation Magazine, IEEE》1992,8(4):16-19
It is shown that the electrical breakdown voltages of polycarbonate film/metal foil capacitors can be increased. This can be achieved by briefly exposing the metal foil in these spirally wound film foil sections to a low-pressure, low-temperature gas plasma. Exposure of tin/lead foil to a 96% CF4/4% O2 gas plasma for four min, for example, produced >500% increase in breakdown voltage of sealed polycarbonate capacitors 相似文献
935.
This article presents an overview of the results of a five-year research project on sensors for the food industry in Japan. This project was a government-sponsered research programme involving the food industry and the instrumentation industry, coordinated by the Japanese Ministry of Agriculture, Forestry and Fisheries. The programme focussed on 17 food processing operations and quality control tasks, where the need for an on-line (or rapid at-line) measurement had been established. The instrument development work employed biosensors pH and gas sensors, optical-imaging devices, as well as near-infrared, microwave, ultrasound and mechanical resonance techniques, together with robotics and advanced data-processing techniques. 相似文献
936.
S Ohkawa A Yamadori K Maeda M Tabuchi Y Ohsumi E Mori T Yoshida Y Yoneda T Uehara 《Canadian Metallurgical Quarterly》1993,56(8):894-896
In right middle cerebral territory infarction a new sign, excessive closure of the right eye ipsilateral to the lesion and mild closure of the left eye on command, was noted. The excessive ipsilateral eye closure was not observed on spontaneous eye closure. 相似文献
937.
T Ojasoo E Bignon A Crastes de Paulet JC Doré J Gilbert JF Miquel M Pons JP Raynaud 《Canadian Metallurgical Quarterly》1993,44(3):239-250
A multivariate statistical method, correspondence factorial (CF) analysis, was used to examine the correlations among the protein binding and cell proliferation effects of a series of 36 di- and triphenylethylenes (DPEs and TPEs). The analysis was applied to a study which measured their competition for estradiol binding to cytosol estrogen receptor (ER), their influence on protein kinase C (PKC) activity under different conditions of enzyme activation, their ability to promote the growth of a breast cancer cell line and to inhibit growth at high concentrations (cytotoxicity). The CF analysis revealed several levels of correlation. First, it distinguished those molecules within the population that stimulated rather than inhibited PKC activity. Second, it made apparent a strong correlation between cytotoxicity and inhibition of Ca++ and phosphatidylserine-dependent PKC activity, which was most marked when the enzyme had been activated by diacylglycerol indicating that PKC inhibition under physiological conditions might contribute to the overall cytotoxicity of these compounds. Third, a lower level of correlation was established between competition for ER binding and cytotoxicity. Taken together, the results suggest that MCF7 cells might be most sensitive to a cytotoxic effect of TPEs (via PKC and other targets) when they at the same time decrease estrogen-stimulated proliferation via an ER-mediated antiestrogenic effect. 相似文献
938.
Antibodies raised against progesterone with hormone-carrier protein bridges placed at four different carbon positions were used to compare the sensitivity and specificity of homologous and heterologous enzyme-hormone conjugates. All heterologous assays were at least twice as sensitive as the corresponding homologous assays. The best results were obtained by using antibodies against 7 alpha-carboxyethyl-thioether-progesterone with 6 beta-hemisuccinate-progesterone conjugate (or hemimaleate). The sensitivity with human sera was 0.25 ng ml-1 and, the highest crossreaction 10% with 5 beta-pregnane-3,20-dione, and reproducibility, recovery and accuracy were satisfactory. The correlation coefficient with radioimmunoassay in 103 human sera tested was r = 0.915. The assay was successfully applied for the diagnosis of pregnancy in dairy cattle. 相似文献
939.
Despite the existence of an impressive body of work on human immune responses against filarial infections, the occurrence of a protective response to infection remains unclear. Here, we use a combined modelling and comparative data analysis framework to address this issue for human infections with the filarial parasite, Wuchereria bancrofti. By analogy with previous work, the analysis involves the comparison of observed field patterns of infection with epidemiological patterns predicted by a mathematical model of parasite immunity. Unlike most other human helminths, which are transmitted by ingestion or dermal penetration, exposure to infection with lymphatic filariasis can be measured explicitly in terms of vector mosquito biting rates, thereby also allowing, probably for the first time, examination of the suggested role of exposure in generating herd immunity to macroparasites. Observed field patterns in this study were derived from 19 different published studies, which gave parallel estimates of community exposure rates and the corresponding age--prevalence patterns of infection, while predictions of the epidemiological impact of herd immunity were obtained using a catalytic model framework. The results provide the first conclusive evidence to date that variations in the observed age--prevalence patterns of infection in filariasis can be effectively explained by the occurrence of an exposure-driven acquisition of herd immunity. We discuss this result in terms of implications for the new World Health Organization-led initiative for the global control of this parasitic disease. 相似文献
940.
Zengerle R. Hubner B. Greus C. Burkhard H. Janning H. Kuphal E. 《Electronics letters》1995,31(14):1142-1143
The monolithic integration of a mushroom type InGaAs-InGaAsP MQW DFB laser with a spot-size transformer based on a two-layer lateral taper is reported. Highly efficient coupling to a butt-joined dispersion shifted singlemode fibre with a coupling loss down to 0.9 dB and large alignment tolerances was achieved, maintaining the good spectral characteristics of an isolated DFB-laser structure 相似文献