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排序方式: 共有377条查询结果,搜索用时 15 毫秒
1.
2.
I. Ladany D.H. Hartman G.R. Lalk K.C. Young Jr. 《Photonics Technology Letters, IEEE》1991,3(8):749-751
One of the most difficult problems in coupling laser diodes to single-mode fibers is maintaining alignment while the two components are locked into place. The authors report a novel approach to the lockup process that uses electroforming. This technique solves the isolation and train relief problem by locking the laser and fiber into a single structure rather than by mounting both to a common base. With this novel technique and simple butt coupling, coupling efficiencies as high as 14% have been achieved with very little alignment shift during lockup. The completed structure is at least 100 times smaller in volume than conventional packages and provides strain relief and isolation from mechanical disturbances.<> 相似文献
3.
Anthony P. Zilko J. Pawlik J. Swaminathan V. Hartman R. 《Quantum Electronics, IEEE Journal of》1982,18(7):1094-1100
Device characteristics of double heterostructure lasers with Al0.4 Ga0.6 As confinement layers and GaAs0.99 Sb0.01 active layers are presented. Average emission wavelengths have been increased from 0.87 μm for undoped active layers to 0.88 μm for2 times 10^{17} cm-3Ge doped active layers with a "wash" melt preceding the growth of the active layer and to 0.89 μ for1 times 10^{18} cm-3Mg doped active layers grown following a "wash" melt. Threshold currents for lasers from 21 wafers are examined for several growth conditions and compared with Al0.08 Ga0.92 As active layer devices. Device resistance, external quantum efficiency, device degradation, and pulsed and CW threshold currents as a function of temperature are also discussed. 相似文献
4.
The need for an efficient, flexible, secure, yet cost-effective multivendor distributed computing environment is discussed. A comprehensive effort toward this goal, the Distributed Computing Environment (DCE) software, is described. Developed by an industry-supported R&D organization with more than 330 members worldwide, the DCE focuses on four problems that require technical solutions: the diversity of operating environments, the (generally large) number of interconnected computers, the need to maintain security, and the need to provide opportunities both for growth and for new network applications 相似文献
5.
An injection-mode InP optical switch array has been characterised at high frequency. A switched optical pulse settling anomaly, which limits the switching performance of the array, is associated with recombination and junction heating effects at the switch heterojunction interface. A simple model describing the effects is presented. Critical design parameters are also identified.<> 相似文献
6.
Genetic fine mapping can be performed by exploiting the notion that haplotypes that are structurally similar in the neighbourhood of a disease predisposing locus are more likely to harbour the same susceptibility allele. Within the framework of Generalized Linear Mixed Models this can be formalized using spatial smoothing models, i.e. inducing a covariance structure for the haplotype risk parameters, such that risks associated with structurally similar haplotypes are dependent. In a Bayesian procedure a local similarity measure is calculated for each update of the presumed disease locus. Thus, the disease locus is searched as the place where the similarity structure produces risk parameters that can best discriminate between cases and controls.From a population genetic perspective the use of an identity-by-descent based similarity metric is theoretically motivated. This approach is then compared to other more intuitively motivated models and other similarity measures based on identity-by-state, suggested in the literature. 相似文献
7.
Bienkowska Jadwiga R.; Hartman Hyman; Smith Temple F. 《Protein engineering, design & selection : PEDS》2003,16(12):897-904
The question of protein homology versus analogy arises whenproteins share a common function or a common structural foldwithout any statistically significant amino acid sequence similarity.Even though two or more proteins do not have similar sequencesbut share a common fold and the same or closely related function,they are assumed to be homologs, descendant from a common ancestor.The problem of homolog identification is compounded in the caseof proteins of 100 or less amino acids. This is due to a limitednumber of basic single domain folds and to a likelihood of identifyingby chance sequence similarity. The latter arises from two conditions:first, any search of the currently very large protein databaseis likely to identify short regions of chance match; secondly,a direct sequence comparison among a small set of short proteinssharing a similar fold can detect many similar patterns of hydrophobicityeven if proteins do not descend from a common ancestor. In aneffort to identify distant homologs of the many ubiquitin proteins,we have developed a combined structure and sequence similarityapproach that attempts to overcome the above limitations ofhomolog identification. This approach results in the identificationof 90 probable ubiquitin-related proteins, including examplesfrom the two prokaryotic domains of life, Archaea and Bacteria. Received December 1, 2002; revised October 22, 2003; accepted October 24, 2003 相似文献
8.
David B. Whitman Christopher D. Cox Dr. Michael J. Breslin Karen M. Brashear John D. Schreier Michael J. Bogusky Dr. Rodney A. Bednar Dr. Wei Lemaire Joseph G. Bruno George D. Hartman Dr. Duane R. Reiss C. Meacham Harrell Richard L. Kraus Dr. Yuxing Li Susan L. Garson Scott M. Doran Dr. Thomayant Prueksaritanont Dr. Chunze Li Dr. Christopher J. Winrow Dr. Kenneth S. Koblan Dr. John J. Renger Paul J. Coleman Dr. 《ChemMedChem》2009,4(7):1069-1074
Silent Night : Antagonism of the orexin (or hypocretin) system has recently been identified as a novel mechanism for the treatment of insomnia. Herein, we describe discovery of a dual (OX1R/OX2R) orexin receptor antagonist featuring a 1,4‐diazepane central constraint that blocks orexin signaling in vivo. In telemetry‐implanted rats, oral administration of this antagonist produced a decrease in wakefulness, while increasing REM and non‐REM sleep.
9.
Jeffrey R Stout B Sue Graves Abbie E Smith Michael J Hartman Joel T Cramer Travis W Beck Roger C Harris 《Journal of the International Society of Sports Nutrition》2008,5(1):1-6
Background
Ageing is associated with a significant reduction in skeletal muscle carnosine which has been linked with a reduction in the buffering capacity of muscle and in theory, may increase the rate of fatigue during exercise. Supplementing beta-alanine has been shown to significantly increase skeletal muscle carnosine. The purpose of this study, therefore, was to examine the effects of ninety days of beta-alanine supplementation on the physical working capacity at the fatigue threshold (PWCFT) in elderly men and women.Methods
Using a double-blind placebo controlled design, twenty-six men (n = 9) and women (n = 17) (age ± SD = 72.8 ± 11.1 yrs) were randomly assigned to either beta-alanine (BA: 800 mg × 3 per day; n = 12; CarnoSyn?) or Placebo (PL; n = 14) group. Before (pre) and after (post) the supplementation period, participants performed a discontinuous cycle ergometry test to determine the PWCFT.Results
Significant increases in PWCFT (28.6%) from pre- to post-supplementation were found for the BA treatment group (p < 0.05), but no change was observed with PL treatment. These findings suggest that ninety days of BA supplementation may increase physical working capacity by delaying the onset of neuromuscular fatigue in elderly men and women.Conclusion
We suggest that BA supplementation, by improving intracellular pH control, improves muscle endurance in the elderly. This, we believe, could have importance in the prevention of falls, and the maintenance of health and independent living in elderly men and women. 相似文献10.
Jack M. Miller Mary Goodchild Jhansi L. Lakshmi David Wails J. Stephen Hartman 《Catalysis Letters》1999,63(3-4):199-203
ZnCl2–aluminosilicate catalysts were prepared via a sol–gel route involving fluoride‐catalyzed hydrolysis of aluminum and silicon
alkoxides in the presence of NaF, KF, NH4F and ZnF2. The catalysts were characterized by employing 29Si, 27Al and 19F solid‐state MAS NMR. The dependence of the activities of the catalysts on the nature and amount of fluoride present in the
catalysts were investigated using Friedel–Crafts alkylation reaction of benzene with benzyl chloride.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献