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41.
The impact of substituting HI for CF3I as the iodine donor in the discharge-pumped iodine monofluoride (IF) laser at 491 nm has been investigated. More than an order of magnitude improvement in output pulse energy has been observed and is attributed to more efficient production of low-lying (v '<5) vibrational levels of the IF (D ') ion pair state. Preliminary evidence indicates that vibrational excitation of HI (X 1Σ+ ) assists in the relaxation of the D ' state population. The increased net small-signal gain of D '→A ' (v '=0→v ") transitions in HI-containing gas mixtures has the effect of intensifying the 491-nm (0.15) bandhead relative to the lower gain transitions 相似文献
42.
Individual differences in working-memory (WM) capacity predicted performance on the Stroop task in 5 experiments, indicating the importance of executive control and goal maintenance to selective attention. When the Stroop task encouraged goal neglect by including large numbers of congruent trials (RED presented in red), low WM individuals committed more errors than did high WM individuals on the rare incongruent trials (BLUE in red) that required maintaining access to the "ignore-the-word" goal for accurate responding. In contrast, in tasks with no or few congruent trials, or in high-congruency tasks that followed low-congruency tasks, WM predicted response-time interference. WM was related to latency, not accuracy, in contexts that reinforced the task goal and so minimized the difficulty of actively maintaining it. The data and a literature review suggest that Stroop interference is jointly determined by 2 mechanisms, goal maintenance and competition resolution, and that the dominance of each depends on WM capacity, as well as the task set induced by current and previous contexts. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
43.
An argument-based approach to validity. 总被引:1,自引:0,他引:1
Outlines a general argument-based approach to validation, develops an interpretive argument for a placement test as an example, and examines some key properties in interpretive arguments. Validity is associated with the interpretation assigned to test scores rather than with the test scores or the test. The interpretation involves an argument leading from the scores to score-based statements or decisions, and the validity of the interpretation depends on the plausibility of this interpretive argument. The interpretive arguments associated with most test-score interpretations involve multiple inferences and assumptions. An explicit recognition of the inferences and assumptions in the interpretive argument makes it possible to identify the kinds of evidence needed to evaluate the argument. Evidence for the inferences and assumptions in the argument supports the interpretation, and evidence against any part of the argument casts doubt on the interpretation. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
44.
Psychoeducational models have been found to be effective interventions for people with schizophrenia. However, a unifying theoretical basis for these models has not been articulated. This article explicates the sense of coherence theory developed by A. Antonovsky (1987) and demonstrates its utility as a framework for conceptualizing the basis for the effectiveness of psychoeducational programs. 相似文献
45.
Adaptive resonance architectures are neural nets that are capable of classifying arbitrary input patterns into stable category representations. A hybrid optoelectronic implementation utilizing an optical joint transform correlator is proposed and demonstrated. The resultant optoelectronic system is able to reduce the number of calculations compared to a strictly computer-based approach. The result is that, for larger images, the optoelectronic system is faster than the computer-based approach. 相似文献
46.
Site-directed mutagenesis of the yeast V-ATPase A subunit 总被引:1,自引:0,他引:1
Q Liu XH Leng PR Newman E Vasilyeva PM Kane M Forgac 《Canadian Metallurgical Quarterly》1997,272(18):11750-11756
To investigate the function of residues at the catalytic nucleotide binding site of the V-ATPase, we have carried out site-directed mutagenesis of the VMA1 gene encoding the A subunit of the V-ATPase in yeast. Of the three cysteine residues that are conserved in all A subunits sequenced thus far, two (Cys284 and Cys539) appear essential for correct folding or stability of the A subunit. Mutation of the third cysteine (Cys261), located in the glycine-rich loop, to valine, generated an enzyme that was fully active but resistant to inhibition by N-ethylmalemide, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole, and oxidation. To test the role of disulfide bond formation in regulation of vacuolar acidification in vivo, we have also determined the effect of the C261V mutant on targeting and processing of the soluble vacuolar protein carboxypeptidase Y. No difference in carboxypeptidase Y targeting or processing is observed between the wild type and C261V mutant, suggesting that disulfide bond formation in the V-ATPase A subunit is not essential for controlling vacuolar acidification in the Golgi. In addition, fluid phase endocytosis of Lucifer Yellow, quinacrine staining of acidic intracellular compartments and cell growth are indistinguishable in the C261V and wild type cells. Mutation of G250D in the glycine-rich loop also resulted in destabilization of the A subunit, whereas mutation of the lysine residue in this region (K263Q) gave a V-ATPase complex which showed normal levels of A subunit on the vacuolar membrane but was unstable to detergent solubilization and isolation and was totally lacking in V-ATPase activity. By contrast, mutation of the acidic residue, which has been postulated to play a direct catalytic role in the homologous F-ATPases (E286Q), had no effect on stability or assembly of the V-ATPase complex, but also led to complete loss of V-ATPase activity. The E286Q mutant showed labeling by 2-azido-[32P]ATP that was approximately 60% of that observed for wild type, suggesting that mutation of this glutamic acid residue affected primarily ATP hydrolysis rather than nucleotide binding. 相似文献
47.
T. Burczyski J. H. Kane C. Balakrishna 《International journal for numerical methods in engineering》1995,38(17):2839-2866
A general approach to shape design sensitivity analysis of three- and two-dimensional elastic solid objects is developed using the material derivative-adjoint variable technique and boundary element method. The formulation of the problem is general and first-order sensitivities in the form of boundary integrals for the effect of boundary shape variations are derived for an arbitrary performance functional. Second-order quadrilateral surface elements (for 3-D problems) and quadratic boundary elements (for 2-D problems) are employed in the solution of primary and adjoint systems and discretization of the boundary integral expressions for sensitivities. The accuracy of sensitivity information is studied for selected global performance functionals and also for boundary state fields at discrete points. Numerical results are presented to demonstrate the accuracy and efficiency of this approach. 相似文献
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Blake Gardner Frederick Ling Philip K Hopke Mark W Frampton Mark J Utell Wojciech Zareba Scott J Cameron David Chalupa Cathleen Kane Suresh Kulandhaisamy Michael C Topf David Q Rich 《Particle and fibre toxicology》2014,11(1):1-11