211 resultados para control theory
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We discuss quantum error correction for errors that occur at random times as described by, a conditional Poisson process. We shoo, how a class of such errors, detected spontaneous emission, can be corrected by continuous closed loop, feedback.
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In this paper, it is shown that, for a wide range of risk-averse generalized expected utility preferences, independent risks are complementary, contrary to the results for expected utility preferences satisfying conditions such as proper and standard risk aversion.
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Dendritic cells (DC) undergo complex developmental changes during maturation. The MHC class H (MHC H) molecules of immature DC accumulate in intracellular compartments, but are expressed at high levels on the plasma membrane upon DC maturation. It has been proposed that the cysteine protease inhibitor cystatin C (CyC) plays a pivotal role in the control of this process by regulating the activity of cathepsin S, a protease involved in removal of the MHC H chaperone E, and hence in the formation of MHC H-peptide complexes. We show that CyC is differentially expressed by mouse DC populations. CD8(+) DC, but not CD4(+) or CD4(-)CD8(-) DC, synthesize CyC, which accumulates in MHC II(+)Lamp(+) compartments. However, II processing and MHC H peptide loading proceeded similarly in all three DC populations. We then analyzed MHC H localization and Ag presentation in CD8(+) DC, bone marrow-derived DC, and spleen-derived DC lines, from CyC-deficient mice. The absence of CyC did not affect the expression, the subcellular distribution, or the formation of peptide-loaded MHC II complexes in any of these DC types, nor the efficiency of presentation of exogenous Ags. Therefore, CyC is neither necessary nor sufficient to control MHC II expression and Ag presentation in DC. Our results also show that CyC expression can differ markedly between closely related cell types, suggesting the existence of hitherto unrecognized mechanisms of control of CyC expression.
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Background and Purpose - This study was undertaken to better clarify the risks associated with cigarette smoking and subarachnoid hemorrhage (SAH). Methods - The study included 432 incident cases of SAH frequency matched to 473 community SAH-free controls to determine dose-dependent associations of active and passive smoking ( at home) and smoking cessation with SAH. Results - Compared with never smokers not exposed to passive smoking, the adjusted odds ratio for SAH among current smokers was 5.0 (95% confidence interval [CI], 3.1 to 8.1); for past smokers, 1.2 ( 95% CI, 0.8 to 2.0); and for passive smokers, 0.9 ( 95% CI, 0.6 to 1.5). Current and lifetime exposures showed a clear dose-dependent effect, and risks appeared more prominent in women and for aneurysmal SAH. Approximately 1 in 3 cases of SAH could be attributed to current smoking, but risks decline quickly after smoking cessation, even among heavy smokers. Conclusions - A strong positive association was found between cigarette smoking and SAH, especially for aneurysmal SAH and women, which is virtually eliminated within a few years of smoking cessation. Large opportunities exist for preventing SAH through smoking avoidance and cessation programs.
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Field trials and laboratory bioassays were undertaken to compare the performance and efficacy (mortality of diamondback moth larvae) of insecticides applied to cabbages with three high volume hydraulic knapsack sprayers (NS-16, PB-20 and Selecta 12V) and a controlled droplet application (CDA) sprayer. In field experiments, the high volume knapsack sprayers (application rate 500-600 L ha(-1)) provided better spray coverage on the upper and lower surfaces of inner leaves, the upper surfaces of middle and outer leaves, and greater biological efficacy than the CDA sprayer (application rate 20similar to40 L ha(-1)). The PB-20 provided better spray coverage on the upper surface of middle leaves and both surfaces of outer leaves when compared with the Selecta 12V. However, its biological efficacy in the field was not significantly different from that of the other high volume sprayers. Increasing the application rate from 20 to 40 L ha(-1) for the CDA sprayer significantly increased droplet density but had no impact on test insect mortality. Laboratory evaluations of biological efficacy yielded higher estimates than field evaluations and there was no significant difference between the performance of the PB-20 and the CDA sprayer. Significant positive relationships were detected between insect mortality and droplet density deposited for both the PB-20 and the CDA sprayers.
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The present exploratory-descriptive cross-national study focused on the career development of 11- to 14-yr.-old children, in particular whether they can match their personal characteristics with their occupational aspirations. Further, the study explored whether their matching may be explained in terms of a fit between person and environment using Holland's theory as an example. Participants included 511 South African and 372 Australian children. Findings relate to two items of the Revised Career Awareness Survey that require children to relate personal-social knowledge to their favorite occupation. Data were analyzed in three stages using descriptive statistics, i.e., mean scores, frequencies, and percentage agreement. The study indicated that children perceived their personal characteristics to be related to their occupational aspirations. However, how this matching takes place is not adequately accounted for in terms of a career theory such as that of Holland.
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In recent years, career development and career counseling have increasingly been informed by concepts emanating from the constructivist worldview. For example, the Systems Theory Framework (STF; M. McMahon, 2002; M. McMahon I W. Patton, 1995; W. Patton I M. McMahon, 1997, 1999) of career development has been proposed as a metatheoretical account of career development. Furthermore, its theoretical constructs may be applied to career counseling. Thus, the STF provides a theoretical and practical consistency to career counseling and addresses concerns about a gulf between career theory and practice. This article discusses the practical application of the STF of career development as a guide to career counseling.
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Increasing recognition of cultural influences on career development requires expanded theoretical and practical perspectives. Theories of career development need to explicate views of culture and provide direction for career counseling with clients who are culturally diverse. The Systems Theory Framework (STF) is a theoretical foundation that accounts for systems of influence on people's career development, including individual, social, and environmental/societal contexts. The discussion provides a rationale for systemic approaches in multicultural career counseling and introduces the central theoretical tenets of the STF. Through applications of the STF, career counselors are challenged to expand their roles and levels of intervention in multicultural career counseling.
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An experiment explored the hypothesis that inhibitory ability helps people stop themselves from engaging in socially inappropriate behavior. All participants completed a Stroop color-naming task, after which half of the participants were asked to remember an eight-digit number (inducing divided attention). Participants were then offered an unfamiliar and visually unappetizing food product (a chicken foot) under conditions of either low or high social pressure to pretend that it was appealing. Participants who had full attention available and were under pressure to pretend the food was appealing were least likely to emit a negative response, and performance on the Stroop task predicted the degree to which they successfully restrained negative responses. These results suggest that the cognitive ability to inhibit unwanted information facilitates socially appropriate behavior.