17,921 research outputs found

    Exploring the Relationship of Ethical Leadership with Job Satisfaction, Organizational Commitment, and Organizational Citizenship Behavior

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    The impact of ethics on recent leadership practices has assumed a prominent role in both practical and theoretical discussions of organizational leadership successes and failures. A leader\u27s ability to affect followers\u27 attitudes and behaviors is important in this pursuit because it can result in greater job performance (Tanner, Brugger, Van Schie, & Lebherz, 2010). Ethical leadership may provide an effective approach for fostering positive employee outlooks and actions. Employees respond positively to the ethical leader\u27s principled leadership, altruism, empowerment, and reward systems, suggesting that improved employee attitudes and work-related behaviors may follow (Brown & Trevino, 2006). Three established measures of attitudes and behaviors are employee job satisfaction, organizational commitment, and organizational citizenship behavior. The following research study examined the potential of ethical leadership to foster higher levels of these outcomes and found that employees led by highly ethical leaders reported greater job satisfaction and organizational commitment than did employees led by less ethical leaders. No significant difference was reported among employees regarding the impact of ethical leadership on their level of organizational citizenship behavior. These findings suggest both theoretical and practitioner level insights

    Look before you leap: a confidence-based method for selecting species criticality while avoiding negative populations in τ\tau-leaping

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    The stochastic simulation algorithm was introduced by Gillespie and in a different form by Kurtz. There have been many attempts at accelerating the algorithm without deviating from the behavior of the simulated system. The crux of the explicit τ\tau-leaping procedure is the use of Poisson random variables to approximate the number of occurrences of each type of reaction event during a carefully selected time period, τ\tau. This method is acceptable providing the leap condition, that no propensity function changes “significantly” during any time-step, is met. Using this method there is a possibility that species numbers can, artificially, become negative. Several recent papers have demonstrated methods that avoid this situation. One such method classifies, as critical, those reactions in danger of sending species populations negative. At most, one of these critical reactions is allowed to occur in the next time-step. We argue that the criticality of a reactant species and its dependent reaction channels should be related to the probability of the species number becoming negative. This way only reactions that, if fired, produce a high probability of driving a reactant population negative are labeled critical. The number of firings of more reaction channels can be approximated using Poisson random variables thus speeding up the simulation while maintaining the accuracy. In implementing this revised method of criticality selection we make use of the probability distribution from which the random variable describing the change in species number is drawn. We give several numerical examples to demonstrate the effectiveness of our new metho

    The pseudo-compartment method for coupling PDE and compartment-based models of diffusion

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    Spatial reaction-diffusion models have been employed to describe many emergent phenomena in biological systems. The modelling technique most commonly adopted in the literature implements systems of partial differential equations (PDEs), which assumes there are sufficient densities of particles that a continuum approximation is valid. However, due to recent advances in computational power, the simulation, and therefore postulation, of computationally intensive individual-based models has become a popular way to investigate the effects of noise in reaction-diffusion systems in which regions of low copy numbers exist. The stochastic models with which we shall be concerned in this manuscript are referred to as `compartment-based'. These models are characterised by a discretisation of the computational domain into a grid/lattice of `compartments'. Within each compartment particles are assumed to be well-mixed and are permitted to react with other particles within their compartment or to transfer between neighbouring compartments. We develop two hybrid algorithms in which a PDE is coupled to a compartment-based model. Rather than attempting to balance average fluxes, our algorithms answer a more fundamental question: `how are individual particles transported between the vastly different model descriptions?' First, we present an algorithm derived by carefully re-defining the continuous PDE concentration as a probability distribution. Whilst this first algorithm shows strong convergence to analytic solutions of test problems, it can be cumbersome to simulate. Our second algorithm is a simplified and more efficient implementation of the first, it is derived in the continuum limit over the PDE region alone. We test our hybrid methods for functionality and accuracy in a variety of different scenarios by comparing the averaged simulations to analytic solutions of PDEs for mean concentrations.Comment: MAIN - 24 pages, 10 figures, 1 supplementary file - 3 pages, 2 figure
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