Decomposing and Solving Timetabling Constraint Networks

The binary version of the school timetabling (STT) problem is a real‐world example of a constraint network that includes only constraints of inequality. A new and useful representation for this real‐world problem, the STT_Grid, leads to a generic decomposition technique. The paper presents proofs of necessary and sufficient conditions for the existence of a solution to decomposed STT_Grids. The decomposition procedure is of low enough complexity to be practical for large problems, such as a real‐world high school.
To test the decomposition approach, a typical high school was analyzed and used as a model for generating STT_Grids of various sizes. Experiments were conducted to test the difficulty of large STT networks and their solution by decomposition. The experimental results show that the decomposition procedure enables the solution of large STT_Grids (620 variables for a real school) in reasonable time. The constraint network of a typical STT_Grid is sparse and belongs to the class of easy problems. Still, due to the sizes of STTs, good constraint satisfaction problem search techniques (i.e., BackJumping and ForwardChecking) do not terminate in reasonable times for STT_Grids that are larger than 300 variables.     

Exercise therapy for depression in middle-aged and older adults: Predictors of early dropout and treatment failure.

Psychosocial factors predicting treatment dropout or failure to benefit from treatment were identified in a randomized trial of exercise therapy and pharmacotherapy for major depression. One hundred fifty-six men and women over age 50 diagnosed with major depressive disorder were assigned to a 16-week program of aerobic exercise, medication (sertraline), or a combination of exercise and medication. Thirty-two patients (21%) failed to complete the program and were considered treatment "dropouts." At the end of 16 weeks, 83 patients (53%) were in remission; the remaining patients not in remission were considered treatment "failures." Baseline levels of self-reported anxiety and life satisfaction were the best predictors of both patient dropout and treatment success or failure across all treatment conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual and Occupational Correlates of the Sick Building Syndrome

Results of a questionnaire survey of 939 workers from 5 air-conditioned offices where smoking was prohibited are reported. Levels of carbon monoxide, carbon dioxide, formaldehde, respirable particulates, and temperature, relative humidity, and illuminance were measured in these buildings, but these did not correlate with symptom reports. The number of sick building syndrome symptoms per worker was related linearly to perceived indoor air quality, job stress, job satisfaction, allergies, eyewear, and seasonal affective disorder. Two hundred and fifty five of these workers also completed a battery of psychological measures. Measures of depression, personality variables, situational stress, vulnerability to stress, and individual differences in circadian rhythms did not correlate with the numbers of sick building syndrome symptoms per worker, although depression did correlate with the number of symptoms when these were weighted for their frequency of occurrence in the previous month. Job stress and perceptions of indoor air quality correlated with both the unweighted and weighted indices of sick building syndrome.     

Raymond Abraham Katzell (1919-2003).

Obituary of Raymond Abraham Katzell (1919-2003) who was renowned for exploring the influence of attitude and leadership on productivity and job satisfaction. Among other things, the obituary notes that in 1965, Ray Katzell and Richard S. Barrett readdressed the issue of testing inequities by asking whether psychological tests--used in employee selection--were equally valid and fair for use with various ethnic groups. With Ford Foundation support, they compiled and analyzed relevant data already available in years of company records. Their findings that such employment tests may, indeed, not always work to the same advantage for all ethnic groups were published in Testing and Fair Employment (Kirkpatrick, Ewen, Barrett, & Katzell, 1968). This book led to Ray's chairing the Department of Labor's Advisory Committee on Testing and Selection, which was influential in the drafting of Office of Federal Contract and Compliance and Equal Employment Opportunity Commission testing guidelines. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Negative supervisory events: Effects on supervision and supervisory alliance.

What are the consequences when a supervisee experiences a negative event in supervision? Supervisee developmental level, supervisory working alliance, trainee attachment style, and negative supervisory events were examined to determine their relationship with one another. Findings underscore the destructive impact negative supervisory events can have on supervision and supervisee development. This impact varies depending upon a supervisee's developmental level or the strength of the supervisor--supervisee working alliance. Supervisors are encouraged to be more supportive of supervisees in early development, and suggestions are offered on ways to ensure a strong supervisory relationship. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sources of social support and burnout, job satisfaction, and productivity.

Social support has been identified as an important correlate of a variety of work outcomes. Support from different sources, including family, coworkers, and supervisors, was examined in 211 traffic enforcement agents (92 men, 119 women). Outcomes included subjective variables (burnout and job satisfaction) and an objective measure of productivity (number of summonses). Support was negatively associated with burnout and positively associated with satisfaction and productivity. A cluster of support variables accounted for 7% of the variance in burnout and productivity and 12% of the variance in job satisfaction. Family support was more closely associated with burnout than with satisfaction or productivity, whereas immediate supervisor support was related to satisfaction and productivity but not burnout. Results suggest that support may be associated with work-related outcomes through multiple pathways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Hierarchical arc consistency: exploiting structured domains in constraint satisfaction problems

Constraint satisfaction problems can be solved by network consistency algorithms that eliminate local inconsistencies before constructing global solutions. We describe a new algorithm that is useful when the variable domains can be structured hierarchically into recursive subsets with common properties and common relationships to subsets of the domain values for related variables. The algorithm, HAC, uses a technique known as hierarchical arc consistency. Its performance is analyzed theoretically and the conditions under which it is an improvement are outlined. The use of HAC in a program for understanding sketch maps, Mapsee3, is briefly discussed and experimental results consistent with the theory are reported.     

计及联盟内部博弈的负荷聚集商优化运营策略

考虑到作为“联盟组织者”的负荷聚集商与作为“联盟成员”的用户间的博弈关系直接影响联盟整体对外竞价及盈利能力,文章以负荷聚集商参与调峰市场为场景,基于纳什讨价还价理论,对负荷调峰效果、负荷聚集商出清能力等因素进行量化并作为不同博弈主体的谈判筹码,建立了负荷聚集商与各类型用户体之间的收益分配模型,并依据用户对调峰电价与电量的不同态度,构建了用户满意度指标。算例仿真结果表明:所提模型能够保证联盟稳固同时增加联盟整体收益,且能合理有效地对主体收益进行分配;制定浮动电价策略能够对用户需求响应形成正向激励,同时提高合作双方的收益。整体与个体的双赢结果验证了所提方法的合理性与优越性。     

一种基于用户终端协助的承载分离机制

针对第五代移动通信网络双连接架构中承载分离算法执行时间间隔过长降低分离算法性能的问题,提出了一种基于用户终端协助的承载分离机制。通过构建用户满意度模型,实时计算用户对网络的满意度,根据终端的用户实时满意度和实际数据接收比向主基站发送终端的反馈消息。主基站根据用户的反馈消息及时调整承载分离比例和切换终端的连接模式。该机制可以与现有的承载分离算法相结合。系统仿真结果表明,相对于传统的承载分离算法,该机制能够提升10%的用户满意度;在通信系统负载较大时,能够提升10%的系统总吞吐量。     

Comparison of four different mobile devices for measuring heart rate and ECG with respect to aspects of usability and acceptance by older people

In the area of product design and usability, most products are developed for the mass-market by technically oriented designers and developers for use by persons who themselves are also technically adept by today's standards. The demands of older people are commonly not given sufficient consideration within the early developmental process. In the present study, the usability and acceptability of four different devices meant to be worn for the measurement of heart rate or ECG were analyzed on the basis of qualitative subjective user ratings and structured interviews of twelve older participants. The data suggest that there was a relatively high acceptance concerning these belts by older adults but none of the four harnesses was completely usable. Especially problematic to the point of limiting satisfaction among older subjects were problems encountered while adjusting the length of the belt and/or closing the locking mechanism. The two devices intended for dedicated heart rate recording yielded the highest user ratings for design, and were clearly preferred for extended wearing time. Yet for all the devices participants identified several important deficiencies in their design, as well as suggestions for improvement. We conclude that the creation of an acceptable monitoring device for older persons requires designers and developers to consider the special demands and abilities of the target group.