Overload, autonomy, and burnout as predictors of physicians' quality of care.

A model in which perceived overload and burnout mediated the relations of workload and autonomy with physicians' quality of care to their patients was examined. The study was based on data from 890 specialists representing six medical specialties. Including global burnout as well as its three first-order facets of physical fatigue, cognitive weariness, and emotional exhaustion improved the fit between the structural model and the data relative to an alternative model that included only global burnout. Workload (number of work hours) indirectly predicted quality of care through perceived overload. Additionally, the authors found that the paths from the first order factors of emotional exhaustion, physical fatigue, and cognitive weariness predicted quality of care negatively, positively, and nonsignificantly, respectively. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Intergroup helping as status relations: Effects of status stability, identification, and type of help on receptivity to high-status group's help.

Integrating research on social identity processes and helping relations, the authors proposed that low-status group members who are high identifiers will be unwilling to receive help from the high-status group when status relations are perceived as unstable and help is dependency-oriented. The first experiment, a minimal group experiment, found negative reactions to help from a high-status outgroup when status relations were unstable. The 2nd and 3rd experiments, which used real groups of Israeli Arabs and Israeli Jews, replicated this finding and showed that high identifiers were less receptive to help from the high-status outgroup than low identifiers. The 4th experiment, a help-seeking experiment with real groups of competing high schools, found that the least amount of help was sought from a high-status group by high identifiers when status relations were perceived as unstable and help was dependency-oriented. Theoretical and applied implications are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Order Reduction Is Invalid for Singularly Perturbed Control Problems with a Vector Fast Variable

The order reduction method for singularly perturbed optimal control systems consists of employing the system obtained while setting the small parameter to zero. In many situations the differential-algebraic system thus obtained indeed provides an appropriate approximation to the singularly perturbed optimal control problem under consideration. In this paper we show, however, that the set of singularly perturbed optimal control systems for which the order reduction approach is invalid is dense (in the L ^∞ norm) in the class of systems which we consider. This is established under the assumption that the fast variable in the singularly perturbed system is not a scalar. Date received: June 8, 2001. Date revised: December 30, 2001.     

Lattice-based flow field modeling

We present an approach for simulating the natural dynamics that emerge from the interaction between a flow field and immersed objects. We model the flow field using the lattice Boltzmann model (LBM) with boundary conditions appropriate for moving objects and accelerate the computation on commodity graphics hardware (GPU) to achieve real-time performance. The boundary conditions mediate the exchange of momentum between the flow field and the moving objects resulting in forces exerted by the flow on the objects as well as the back-coupling on the flow. We demonstrate our approach using soap bubbles and a feather. The soap bubbles illustrate Fresnel reflection, reveal the dynamics of the unseen flow field in which they travel, and display spherical harmonics in their undulations. Our simulation allows the user to directly interact with the flow field to influence the dynamics in real time. The free feather flutters and gyrates in response to lift and drag forces created by its motion relative to the flow. Vortices are created as the free feather falls in an otherwise quiescent flow.     

Footprint area sampled texturing

We study texture projection based on a four region subdivision: magnification, minification, and two mixed regions. We propose improved versions of existing techniques by providing exact filtering methods which reduce both aliasing and overblurring, especially in the mixed regions. We further present a novel texture mapping algorithm called FAST (footprint area sampled texturing), which not only delivers high quality, but also is efficient. By utilizing coherence between neighboring pixels, performing prefiltering, and applying an area sampling scheme, we guarantee a minimum number of samples sufficient for effective antialiasing. Unlike existing methods (e.g., MlP-map, Feline), our method adapts the sampling rate in each chosen MlP-map level separately to avoid undersampling in the lower level l for effective antialiasing and to avoid oversampling in the higher level l+1 for efficiency. Our method has been shown to deliver superior image quality to Feline and other methods while retaining the same efficiency. We also provide implementation trade offs to apply a variable degree of accuracy versus speed.     

Principles of 2-sliding mode design

Second-order sliding modes are used to keep exactly a constraint of the second relative degree or just to avoid chattering, i.e. in the cases when the standard (first order) sliding mode implementation might be involved or impossible. Design of a number of new 2-sliding controllers is demonstrated by means of the proposed homogeneity-based approach. A recently developed robust exact differentiator being applied, robust output-feedback controllers with finite-time convergence are produced, capable to control any general uncertain single-input-single-output process with relative degree 2. An effective simple procedure is developed to attenuate the 1-sliding mode chattering. Simulation of new controllers is presented.     

A robust optimisation model and cutting planes for the planning of energy-efficient wireless networks

In this paper, we present an optimisation model for the energy-efficient planning of future wireless networks. By applying robust optimisation, we extend this model to a robust formulation which considers demand uncertainties. The computability of the resulting model is moderate. Hence, we apply three different cutting plane approaches for an improvement. Furthermore, an extensive case study is performed to examine the price of robustness, to compare the robust solution to conventional planning, and to explore the performance of the cutting planes.     

Pneumatic actuator control: Solution based on adaptive twisting and experimentation

An adaptive version of the twisting algorithm is proposed, which actually presents a new second-order sliding-mode algorithm. Due to the dynamic adaptation of the gains the controller design does not require complete information on the bounds of uncertainties and perturbations. It automatically decreases the gains and respectively also the dangerous oscillations due to a too large discontinuous-control magnitude. Thus, both the performance and the accuracy of the closed-loop system are improved. In order to show the feasibility of the approach, the methodology is successfully applied to control the position of a pneumatic actuator in an experimental setup.