Torsional vibrations of open and variable crosssection bars

This work gives exact solutions for the torsional vibration frequencies of symmetric variable and open cross-section bars. An analytical method is derived to form the dynamic stiffness matrix of the bar, including the effect of warping. An example is given and compared to approximate results. The effect of warping is demonstrated.     

Leader–member exchange and affective organizational commitment: The contribution of supervisor's organizational embodiment.

In order to account for wide variation in the relationship between leader–member exchange and employees' affective organizational commitment, we propose a concept termed supervisor's organizational embodiment (SOE), which involves the extent to which employees identify their supervisor with the organization. With samples of 251 social service employees in the United States (Study 1) and 346 employees in multiple Portuguese organizations (Study 2), we found that as SOE increased, the association between leader–member exchange and affective organizational commitment became greater. This interaction carried through to in-role and extra-role performance. With regard to antecedents, we found in Study 1 that supervisor's self-reported identification with the organization increased supervisor's expression of positive statements about the organization, which in turn increased subordinates' SOE. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Competing risks mixture model for traffic incident duration prediction

Traffic incident duration is known to result from a combination of multiple factors, including covariates such as spatial and temporal characteristics, traffic conditions, and existence of secondary accidents but also the clearance method itself. In this paper, a competing risks mixture model is used to investigate the influence of clearance methods and various covariates on the duration of traffic incidents and predict traffic incident duration. The proposed mixture model considers the uncertainty in any of five clearance methods that occurred. The probability of the clearance method is specified in the mixture by using a multinomial logistic model. Three candidate distributions, namely, generalized gamma, Weibull, and log-logistic are tested to determine the most appropriate probability density function of the parametric survival analysis model. The unobserved heterogeneity is also incorporated into the mixture model in a way that allows parameters to vary across observations based on the three candidate distributions. The methods are illustrated with incident data from Singaporean expressways from January 2010 to December 2011. Regression analysis reveals that the probability of different clearance methods and the duration of traffic incidents are both significantly affected by various factors, such as traffic conditions and incident characteristics. Results show that the proposed mixture model is better than the traditional accelerated failure time model, and it predicts traffic incident duration with reasonable accuracy, as shown by the mean average percent error.     

Personalized Cardio‐Metabolic Responses to an Anti‐Inflammatory Nutrition Intervention in Obese Adolescents: A Randomized Controlled Crossover Trial

1 Scope

Chronic inflammation and hypoadiponectinemia are characteristics of obesity‐induced insulin resistance (IR). The effect of an anti‐inflammatory nutrition supplement (AINS) on IR and adiponectin biology in overweight adolescents was investigated. The secondary objective was to examine the extent to which individuals’ biomarker profiles, derived from baseline phenotypes, predicted response or not to the AINS. Additionally, the impact of DNA methylation on intervention efficacy was assessed.

2 Methods and results

Seventy overweight adolescents (13–18 years) were recruited to this randomized controlled crossover trial. Participants received an AINS (long chain n‐3 PUFA, vitamin C, α‐tocopherol, green tea extract, and lycopene) and placebo for 8 weeks each. Homeostatic model assessment (HOMA)‐IR, adiponectin, inflammatory profiles, and DNA methylation were assessed. HOMA‐IR was unchanged in the total cohort. High‐molecular‐weight (HMW) adiponectin was maintained following the AINS while it decreased over time following the placebo intervention. HOMA‐IR decreased in 40% of subjects (responders) following the AINS. Responders’ pretreatment phenotype was characterized by higher HOMA‐IR, total and LDL cholesterol, but similar BMI in comparison to nonresponders. HMW adiponectin response to the AINS was associated with bidirectional modulation of adipogenic gene methylation.

3 Conclusion

The AINS modulated adiponectin biology, an early predictor of type 2 diabetes risk, was associated with bidirectional modulation of adipogenic gene methylation in weight‐stable overweight adolescents. HOMA‐IR decreased in a sub‐cohort of adolescents with an adverse metabolic phenotype. Thus, suggesting that more stratified or personalized nutrition approaches may enhance efficacy of dietary interventions.     

Beam Bending Solutions Based on Nonlocal Timoshenko Beam Theory

This paper is concerned with the bending problem of micro- and nanobeams based on the Eringen nonlocal elasticity theory and Timoshenko beam theory. In the former theory, the small-scale effect is taken into consideration while the effect of transverse shear deformation is accounted for in the latter theory. The governing equations and the boundary conditions are derived using the principle of virtual work. General solutions for the deflection, rotation, and stress resultants are presented for transversely loaded beams. In addition, specialized bending solutions are given for beams with various end conditions. These solutions account for a better representation of the bending behavior of short, stubby, micro- and nanobeams where the small-scale effect and transverse shear deformation are significant. Considering particular loading and boundary conditions, the effects of small-scale and shear deformation on the bending results may be observed because of the analytical forms of the solutions.     

The Role of Plant Rapidly Induced Responses in Asymmetric Interspecific Interactions Among Insect Herbivores

The role of induced responses of tomato, Lycopersicon esculentum, in interspecific interactions between two polyphagous herbivores, the silverleaf whitefly, Bemisia argentifolii (WF), and the vegetable leafminer, Liriomyza trifolii (LM), was characterized in laboratory and field experiments. Feeding by LMs and WFs induced local and systemic production of putative defensive proteins, i.e., chitinases, peroxidases, -1,3-glucanases, and lysozymes. The magnitude of the induction for each defensive protein varied between species. Unlike WFs, LMs caused a 33% local reduction in total foliar protein content. In a whole-plant choice experiment, adult LM feeding, oviposition, and larval survival were reduced by 47.7%, 30.7%, and 26.5%, respectively, for the WF-infested host compared with the controls. Early WF infestations also had negative systemic (plant-mediated) effects on LMs. Adult LMs preferred leaves from control plants to leaves of plants that had been previously infested with WFs; no reciprocal effect of LMs on WFs were found. Feeding by Helicoverpa zea larvae, which has been shown previously to affect LM performance, had no effect on WF survival and development. LM natural population dynamics were monitored on WF-preinfested and control plants in a field experiment. WF-infested plants were less suitable for LM development with an overall 41% reduction in LM population density. These results demonstrate asymmetric direct and plant-mediated interspecific interactions between generalist herbivores feeding simultaneously on the same host. Possible mechanisms by which WFs overcome plant defenses are suggested. This ability may also contribute to WF success that makes them a major pest worldwide. The study supports the idea that over an evolutionary time scale, herbivores sharing the same host plant will automatically compete.     

Symbolic systems,explicit properties: on hybrid approaches for LTL symbolic model checking

In this work we study hybrid approaches to LTL symbolic model checking; that is, approaches that use explicit representations of the property automaton, whose state space is often quite manageable, and symbolic representations of the system, whose state space is typically exceedingly large. We compare the effects of using, respectively, (i) a purely symbolic representation of the property automaton, (ii) a symbolic representation, using logarithmic encoding, of explicitly compiled property automaton, and (iii) a partitioning of the symbolic state space according to an explicitly compiled property automaton. We apply this comparison to three model-checking algorithms: the doubly-nested fixpoint algorithm of Emerson and Lei, the reduction of emptiness to reachability of Biere et al., and the singly-nested fixpoint algorithm of Bloem et al. for weak automata. The emerging picture from our study is quite clear, hybrid approaches outperform pure symbolic model checking, while partitioning generally performs better than logarithmic encoding. The conclusion is that the hybrid approaches benefit from state-of-the-art techniques in semantic compilation of LTL properties. Partitioning gains further from the fact that the image computation is applied to smaller sets of states.     

Obtaining small photovoltaic array operational curves for arbitrary cell temperatures and solar irradiation densities from standard conditions data

The paper presents a simple approach to deriving I–V curves of photovoltaic panels and small arrays for arbitrary environmental conditions on the basis of three points of a single operating curve data and short current temperature coefficient only. The proposed method does not employ fitting of any type and is solely based on a numerical solution of a system of transcendental equations. The equations are expressed in a dimensionless form, simplifying both the solution and photovoltaic panel parameters' representation. The solution is used to find the values of normalized equivalent circuit elements for the available data and then perform an appropriate adjustment to obtain the operating curves for arbitrary conditions. The proposed method was applied to monocrystalline and polycrystalline commercial solar panels and was compared with both manufacturer‐provided and experimentally measured operating curves to analyze the approach applicability and accuracy. Copyright © 2012 John Wiley & Sons, Ltd.