Global optimization in protein docking using clustering,underestimation and semidefinite programming

The underestimation of data points by a convex quadratic function is a useful tool for approximating the location of the global minima of potential energy functions that arise in protein-ligand docking problems. Determining the parameters that define the underestimator can be formulated as a convex quadratically constrained quadratic program and solved efficiently using algorithms for semidefinite programming (SDP). In this paper, we formulate and solve the underestimation problem using SDP and present numerical results for active site prediction in protein docking.     

Biases and fallacies, memories and predictions: Comment on Roy, Christenfeld, and McKenzie (2005).

Comparative theory testing is a useful method for assessing the value of a new theoretical account such as the memory bias account of optimistic time predictions. However, such comparisons can be misleading when they do not carefully consider the domain limitations of the respective theories. M. M. Roy, N. J. S. Christenfeld, and C. R. M. McKenzie (see record 2005-11504-008) have contrasted the memory bias and planning fallacy accounts in their ability to explain the prevalence and degree of optimistic bias in time predictions. However, the authors argue that many of the points of distinction they draw are actually reflections of the domain limitations of the 2 theories. The authors clarify the definition and scope of the planning fallacy account and show how the apparent contradictions diminish or disappear. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

基于广义凸下界估计的多模态差分进化算法

针对多模态优化问题,提出了基于广义凸下界估计模型的改进差分进化算法。首先,基于模型变换方法将原优化问题转变为单位单纯形约束条件下的严格递增射线凸优化问题;其次,基于广义凸理论,利用差分进化算法中更新个体的适应度知识,建立原优化问题广义凸下界估计模型,设计实现了基于 N-叉树的估计模型快速计算方法;进而,综合考虑原问题目标值与其估计值之间的差异,提出一种基于有偏采样的小生境指标,并设计区域进化树更新策略来保证算法的局部搜索能力。数值实验结果表明,提出的算法能够有效地发现并维持一定数量的满意解模态,动态地实现全局模态搜索到模态内局部增强的自适应平滑过渡。对于给出的测试问题,能够发现所有的全局最优解以及一些较好的局部极值解。     

Integrated production planning and scheduling using a decomposition framework

To ensure the consistency between planning and scheduling decisions, the integrated planning and scheduling problem should be addressed. Following the natural hierarchy of decision making, integrated planning and scheduling problem can be formulated as bilevel optimization problem with a single planning problem (upper level) and multiple scheduling subproblems (lower level). Equivalence between the proposed bilevel model and a single level formulation is proved considering the special structure of the problem. However, the resulting model is still computationally intractable because of the integrality restrictions and large size of the model. Thus a decomposition based solution algorithm is proposed in this paper. In the proposed method, the production feasibility requirement is modeled through penalty terms on the objective function of the scheduling subproblems, which is further proportional to the amount of unreachable production targets. To address the nonconvexity of the production cost function of the scheduling subproblems, a convex polyhedral underestimation of the production cost function is developed to improve the solution accuracy. The proposed decomposition framework is illustrated through examples which prove the effectiveness of the method.     

Chronicity of Psychological Strain in Occupational Settings and the Accuracy of the General Health Questionnaire.

This article examines the proposition that the traditional scoring method of the General Health Questionnaire (GHQ) underestimates the number of respondents classified as "cases." A revised "chronic" scoring method (the CGHQ) is used and demonstrates superior construct validity and greater sensitivity. A comparison of the CGHQ and GHQ also shows the CGHQ to be a superior criterion measure. These claims are demonstrated by survey data gathered from 3 occupational samples (Ns = 11,637, 2,253, and 2,124). Results show that the CGHQ is more appropriate as a screening instrument for psychological morbidity. Tests of construct validity also favor the CGHQ with only a slight advantage for predictive validity in terms of variance explained. The more desirable statistical properties of the CGHQ result in a reduction of significant interaction terms and are strongly recommended in future studies as a means of controlling Type I errors when tests of moderation are examined. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unskilled, unaware, or both? The better-than-average heuristic and statistical regression predict errors in estimates of own performance.

People who score low on a performance test overestimate their own performance relative to others, whereas high scorers slightly underestimate their own performance. J. Kruger and D. Dunning (1999) attributed these asymmetric errors to differences in metacognitive skill. A replication study showed no evidence for mediation effects for any of several candidate variables. Asymmetric errors were expected because of statistical regression and the general better-than-average (BTA) heuristic. Consistent with this parsimonious model, errors were no longer asymmetric when either regression or the BTA effect was statistically removed. In fact, high rather than low performers were more error prone in that they were more likely to neglect their own estimates of the performance of others when predicting how they themselves performed relative to the group. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Underestimating the Duration of Future Events: Memory Incorrectly Used or Memory Bias?

People frequently underestimate how long it will take them to complete a task. The prevailing view is that during the prediction process, people incorrectly use their memories of how long similar tasks have taken in the past because they take an overly optimistic outlook. A variety of evidence is reviewed in this article that points to a different, although not mutually exclusive, explanation: People base predictions of future duration on their memories of how long past events have taken, but these memories are systematic underestimates of past duration. People appear to underestimate future event duration because they underestimate past event duration. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The broad applicability of memory bias and its coexistence with the planning fallacy: Reply to Griffin and Buehler (2005).

People chronically underestimate how long tasks will take. In their original article, the present authors (M. M. Roy, N. J. S. Christenfeld, & C. R. M. McKenzie, see record 2005-11504-008) suggested a simple, broadly applicable explanation: Biased predictions result from biased memories. In their comment article, D. Griffin and R. Buehler (see record 2005-11504-009) suggested that in many domains in which this memory-bias account appears to outpredict their own account, theirs actually makes no prediction at all. However, the present authors did not suggest that only 1 theory is right but that theirs is consistent with data that prior theories, including their own, cannot explain. Ignoring memories of past tasks is not a complete explanation for the phenomenon if the memories people could consult are themselves biased. Nonetheless, underestimating future task duration is almost certainly multiply determined, and thus our account and theirs can coexist. (PsycINFO Database Record (c) 2010 APA, all rights reserved)