Observable Behavior of Dynamic Systems: Component Reasoning for Concurrent Objects

Current object-oriented approaches to distributed programs may be criticized in several respects. First, method calls are generally synchronous, which leads to much waiting in distributed and unstable networks. Second, the common model of thread concurrency makes reasoning about program behavior very challenging. Models based on concurrent objects communicating by asynchronous method calls, have been proposed to combine object orientation and distribution in a more satisfactory way. In this paper, a high-level language and proof system are developed for such a model, emphasizing simplicity and modularity. In particular, the proof system is used to derive external specifications of observable behavior for objects, encapsulating their state. A simple and compositional proof system is paramount to allow verification of real programs. The proposed proof rules are derived from the Hoare rules of a standard sequential language by a semantic encoding preserving soundness and relative completeness. Thus, the paper demonstrates that these models not only address the first criticism above, but also the second.     

Enhanced incorporation of n−3 fatty acids from fish compared with fish oils

This work was undertaken to study the impact of the source of n−3 FA on their incorporation in serum, on blood lipid composition, and on cellular activation. A clinical trial comprising 71 volunteers, divided into five groups, was performed. Three groups were given 400 g smoked salmon (n=14), cooked salmon (n=15), or cooked cod (n=13) per week for 8 wk. A fourth group was given 15 mL/d of cod liver oil (CLO) (n=15), and a fifth group served as control (n=14) without supplementation. The serum content of EPA and DHA before and after intervention revealed a higher rise in EPA and DHA in the cooked salmon group (129% rise in EPA and 45% rise in DHA) as compared with CLO (106 and 25%, respectively) despite an intake of EPA and DHA in the CLO group of 3.0 g/d compared with 1.2 g/d in the cooked salmon group. No significant changes were observed in blood lipids, fibrinogen, fibrinolysis, or lipopolysaccharide (LPS)-induced tissue factor (TF) activity, tumor necrosis factor-α (TNFα), interleukin-8 (IL-8), leukotriene B₄ (LTB₄), and thromboxane B₂ (TxB₂) in whole blood. EPA and DHA were negatively correlated with LPS-induced TNFα, IL-8, LTB₄, TxB₂, and TF in whole blood. In conclusion, fish consumption is more effective in increasing serum EPA and DHA than supplementing the diet with fish oil. Since the n−3 FA are predominantly in TAG in fish as well as CLO, it is suggested that the larger uptake from fish than CLO is due to differences in physiochemical structure of the lipids.     

Dimensions of teacher self-efficacy and relations with strain factors, perceived collective teacher efficacy, and teacher burnout.

In this study, the authors developed and factor analyzed the Norwegian Teacher Self-Efficacy Scale. They also examined relations among teacher self-efficacy, perceived collective teacher efficacy, external control (teachers' general beliefs about limitations to what can be achieved through education), strain factors, and teacher burnout. Participants were 244 elementary and middle school teachers. The analysis supported the conceptualization of teacher self-efficacy as a multidimensional construct. They found strong support for 6 separate but correlated dimensions of teacher self-efficacy, which were included in the following subscales: Instruction, Adapting Education to Individual Students' Needs, Motivating Students, Keeping Discipline, Cooperating With Colleagues and Parents, and Coping With Changes and Challenges. They also found support for a strong 2nd-order self-efficacy factor underlying the 6 dimensions. Teacher self-efficacy was conceptually distinguished from perceived collective teacher efficacy and external control. Teacher self-efficacy was strongly related to collective teacher efficacy and teacher burnout. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effect of office concepts on worker health and performance: a systematic review of the literature

Conventional and innovative office concepts can be described according to three dimensions: (1) the office location (e.g. telework office versus conventional office); (2) the office lay-out (e.g. open lay-out versus cellular office); and (3) the office use (e.g. fixed versus shared workplaces). This review examined how these three office dimensions affect the office worker's job demands, job resources, short- and long-term reactions. Using search terms related to the office concept (dimensions), a systematic literature search starting from 1972 was conducted in seven databases. Subsequently, based on the quality of the studies and the consistency of the findings, the level of evidence for the observed findings was assessed. Out of 1091 hits 49 relevant studies were identified. Results provide strong evidence that working in open workplaces reduces privacy and job satisfaction. Limited evidence is available that working in open workplaces intensifies cognitive workload and worsens interpersonal relations; close distance between workstations intensifies cognitive workload and reduces privacy; and desk-sharing improves communication. Due to a lack of studies no evidence was obtained for an effect of the three office dimensions on long-term reactions. The results suggest that ergonomists involved in office innovation could play a meaningful role in safeguarding the worker's job demands, job resources and well-being. Attention should be paid, in particular, to effects of workplace openness by providing acoustic and visual protection.     

Application of the finite element method to machinery

The finite element method has given the designer of machinery components and structures a new tool for analysis of stresses, temperatures and dynamic vibrations.In the following some applications of the tool to different problems within this field are shown (by some examples), using the SESAM-69 complex.Three-dimensional solids as well as three-dimensional plate and bar structures are treated, and the results are compared to analytical or experimental solutions where such are known.These examples should verify the FEM as very attractive to the modem machinery-designer.