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排序方式: 共有253条查询结果,搜索用时 15 毫秒
1.
This paper studies how an overall fuzzy preference relation can be constructed in the compensatory context of the simple additive difference model, when imprecision on the trade-offs has to be taken into account. Three credibility indices of preferences are analysed and illustrated by a numerical example. Arguments are presented supporting the use of the third index, for which an interesting transitivity property (which was an open problem) is proved.  相似文献   
2.
Search algorithms are often compared by the optimization speed achieved on some sets of cost functions. Here some properties of algorithms’ optimization speed are introduced and discussed. In particular, we show that determining whether a set of cost functions F admits a search algorithm having given optimization speed is an NP-complete problem. Further, we derive an explicit formula to calculate the best achievable optimization speed when F is closed under permutation. Finally, we show that the optimization speed achieved by some well-know optimization techniques can be much worse than the best theoretical value, at least on some sets of optimization benchmarks.  相似文献   
3.
This paper investigates the foreign funding mix of globally active banks. Using BIS international banking statistics for a panel of 12 advanced economies, we detect a structural break in international bank funding at the onset of the great financial crisis. In their postbreak business model, banks rely less on cross‐border liabilities and, instead, tap funds from outside their jurisdictions by making more active use of their subsidiaries and branches, as well as interoffice accounts within the same banking group. (JEL C32, F65, G21)  相似文献   
4.
What are the local characteristics influencing where new nonprofits will be established? How important are community needs, available resources, or the existence of similar organizations for nonprofits’ location? This paper analyzes how the characteristics of 5562 Brazilian municipalities in the year 2000 help explain the location of nonprofits formed between 2001 and 2010. Based on geographically weighted regressions, results indicate that neither access to resources nor poor socioeconomic indicators are powerful influences on nonprofit location in Brazilian municipalities. The main predictor of nonprofit entry is a high pre-existing density of nonprofits in that area. These findings, however, vary across regions and nonprofit fields of activity. By mapping the effect of key explanatory variables, this paper helps understand nonprofit location. The methodology and findings on nonprofit location presented here are novel and may contribute to research in other countries.  相似文献   
5.
We estimate a dynamic model of employment, human capital accumulation—including education, and savings for women in the United Kingdom, exploiting tax and benefit reforms, and use it to analyze the effects of welfare policy. We find substantial elasticities for labor supply and particularly for lone mothers. Returns to experience, which are important in determining the longer‐term effects of policy, increase with education, but experience mainly accumulates when in full‐time employment. Tax credits are welfare improving in the U.K., increase lone‐mother labor supply and marginally reduce educational attainment, but the employment effects do not extend beyond the period of eligibility. Marginal increases in tax credits improve welfare more than equally costly increases in income support or tax cuts.  相似文献   
6.
In this paper, we consider a statistical estimation problem known as atomic deconvolution. Introduced in reliability, this model has a direct application when considering biological data produced by flow cytometers. From a statistical point of view, we aim at inferring the percentage of cells expressing the selected molecule and the probability distribution function associated with its fluorescence emission. We propose here an adaptive estimation procedure based on a previous deconvolution procedure introduced by Es, Gugushvili, and Spreij [(2008), ‘Deconvolution for an atomic distribution’, Electronic Journal of Statistics, 2, 265–297] and Gugushvili, Es, and Spreij [(2011), ‘Deconvolution for an atomic distribution: rates of convergence’, Journal of Nonparametric Statistics, 23, 1003–1029]. For both estimating the mixing parameter and the mixing density automatically, we use the Lepskii method based on the optimal choice of a bandwidth using a bias-variance decomposition. We then derive some convergence rates that are shown to be minimax optimal (up to some log terms) in Sobolev classes. Finally, we apply our algorithm on the simulated and real biological data.  相似文献   
7.
This study compares the efficacy of 2 psychoeducational interventions—ACCENT skills-based and didactic information only—to prevent HIV among Portuguese women. At posttest and follow-up, participants in both intervention groups (n = 127) were more knowledgeable about HIV than at baseline. Although both intervention groups showed an increase in self-reported condom use over time, differences were marginally stronger in the ACCENT group. Both intervention groups showed more positive results than the non-intervention control group (n = 33). The study suggests that HIV prevention interventions can produce significant changes when they target a set of knowledge, social, and cognitive variables relevant to sexual behavior change.  相似文献   
8.
Clustered binary responses are often found in ecological studies. Data analysis may include modeling the marginal probability response. However, when the association is the main scientific focus, modeling the correlation structure between pairs of responses is the key part of the analysis. Second-order generalized estimating equations (GEE) are established in the literature. Some of them are more efficient in computational terms, especially facing large clusters. Alternating logistic regression (ALR) and orthogonalized residual (ORTH) GEE methods are presented and compared in this paper. Simulation results show a slightly superiority of ALR over ORTH. Marginal probabilities and odds ratios are also estimated and compared in a real ecological study involving a three-level hierarchical clustering. ALR and ORTH models are useful for modeling complex association structure with large cluster sizes.  相似文献   
9.
Job insecurity has received growing attention from researchers because it poses serious challenges for organisations and for society as a whole. However, there are insufficient studies about the processes through which job insecurity affects outcomes as well as potential ways to reduce its negative impact. This study focuses on the relationship between job insecurity and individual-level outcomes (in-role performance and organisational deviance) and examines if (a) job insecurity is positively and/or negatively related to work outcomes, (b) psychological contract breach acts as a mediator of the relationship between job insecurity and work outcomes, and (c) positive psychological capital (PsyCap) buffers the job insecurity–work outcomes relationship via psychological contract breach. With a sample of 362 employee–supervisor dyads, in which the outcome measures were collected from the supervisors, we found support for our hypotheses. Specifically, we found a moderated mediation effect, whereby PsyCap moderates the negative indirect relationship of job insecurity on outcomes through psychological contract breach.  相似文献   
10.
Introduction: Metabolic syndrome (MetS) is a constellation of interrelated risk factors of metabolic origin. Some studies suggest a possible link between low total testosterone (TT) levels and the presence of MetS.

Aim: To analyze the strength and independence of associations between TT and MetS components in non-diabetic men.

Methods: In this cross-sectional study, 143 non-diabetic men older than 40 were analyzed.

Main outcomes measure: Blood samples were collected to evaluate metabolic profile and TT levels. MetS was defined as the presence of three or more of the following characteristics: fasting blood glucose levels?≥?100?mg/dL, triglyceride?≥?150?mg/dL, HDL-c??102?cm.

Results: Mean age of the study population was 61.5?±?8.61 years old. MetS was present in 47.9% of the individuals. Thirty-four men had low TT and MetS was observed in 23 (70%) against 50 (46%) in those with normal TT (≥?300?ng/dL) (OR 4.94, p?p?=?0.03) and HDL-c (Beta: 0.19; p?=?0.04) remained significantly correlated with TT levels.

Conclusions: Low TT levels were associated with MetS diagnosis. Abdominal obesity was the MetS component independently correlated to low TT levels.  相似文献   
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