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Terms modified by Unstructured Selected AbstractsA hybrid immersed boundary and material point method for simulating 3D fluid,structure interaction problemsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 12 2008Anvar Gilmanov Abstract A numerical method is developed for solving the 3D, unsteady, incompressible Navier,Stokes equations in curvilinear coordinates containing immersed boundaries (IBs) of arbitrary geometrical complexity moving and deforming under forces acting on the body. Since simulations of flow in complex geometries with deformable surfaces require special treatment, the present approach combines a hybrid immersed boundary method (HIBM) for handling complex moving boundaries and a material point method (MPM) for resolving structural stresses and movement. This combined HIBM & MPM approach is presented as an effective approach for solving fluid,structure interaction (FSI) problems. In the HIBM, a curvilinear grid is defined and the variable values at grid points adjacent to a boundary are forced or interpolated to satisfy the boundary conditions. The MPM is used for solving the equations of solid structure and communicates with the fluid through appropriate interface-boundary conditions. The governing flow equations are discretized on a non-staggered grid layout using second-order accurate finite-difference formulas. The discrete equations are integrated in time via a second-order accurate dual time stepping, artificial compressibility scheme. Unstructured, triangular meshes are employed to discretize the complex surface of the IBs. The nodes of the surface mesh constitute a set of Lagrangian control points used for tracking the motion of the flexible body. The equations of the solid body are integrated in time via the MPM. At every instant in time, the influence of the body on the flow is accounted for by applying boundary conditions at stationary curvilinear grid nodes located in the exterior but in the immediate vicinity of the body by reconstructing the solution along the local normal to the body surface. The influence of the fluid on the body is defined through pressure and shear stresses acting on the surface of the body. The HIBM & MPM approach is validated for FSI problems by solving for a falling rigid and flexible sphere in a fluid-filled channel. The behavior of a capsule in a shear flow was also examined. Agreement with the published results is excellent. Copyright © 2007 John Wiley & Sons, Ltd. [source] Emergency Medicine Practitioner Knowledge and Use of Decision Rules for the Evaluation of Patients with Suspected Pulmonary Embolism: Variations by Practice Setting and Training LevelACADEMIC EMERGENCY MEDICINE, Issue 1 2007Michael S. Runyon MD Abstract Background Several clinical decision rules (CDRs) have been validated for pretest probability assessment of pulmonary embolism (PE), but the authors are unaware of any data quantifying and characterizing their use in emergency departments. Objectives To characterize clinicians' knowledge of and attitudes toward two commonly used CDRs for PE. Methods By using a modified Delphi approach, the authors developed a two-page paper survey including 15 multiple-choice questions. The questions were designed to determine the respondents' familiarity, frequency of use, and comprehension of the Canadian and Charlotte rules. The survey also queried the frequency of use of unstructured (gestalt) pretest probability assessment and reasons why physicians choose not to use decision rules. The surveys were sent to physicians, physician assistants, and medical students at 32 academic and community hospitals in the United States and the United Kingdom. Results Respondents included 555 clinicians; 443 (80%) work in academic practice, and 112 (20%) are community based. Significantly more academic practitioners (73%) than community practitioners (49%) indicated familiarity with at least one of the two decision rules. Among all respondents familiar with a rule, 50% reported using it in more than half of applicable cases. A significant number of these respondents could not correctly identify a key component of the rule (23% for the Charlotte rule and 43% for the Canadian rule). Fifty-seven percent of all respondents indicated use of gestalt rather than a decision rule in more than half of cases. Conclusions Academic clinicians were more likely to report familiarity with either of these two specific decision rules. Only one half of all clinicians reporting familiarity with the rules use them in more than 50% of applicable cases. Spontaneous recall of the specific elements of the rules was low to moderate. Future work should consider clinical gestalt in the evaluation of patients with possible PE. [source] Applying the Collective Causal Mapping Methodology to Operations Management Curriculum Development,DECISION SCIENCES JOURNAL OF INNOVATIVE EDUCATION, Issue 2 2007Julie M. Hays ABSTRACT Although the field of operations management has come a long way since its beginnings in scientific management, the field still appears somewhat amorphous and unstructured to many. Introductory operations management textbooks usually include a number of largely disjointed topics, which leave many students (and their instructors) without a coherent framework for understanding the field. As a result, the importance and sequencing of topics varies widely between courses and instructors, even within the same university. This article applies the newly developed Collective Causal Mapping Methodology to create a causal map for the entire field of operations management. The causal map is built on expert opinions collected from over 250 academics and practitioners representing many areas of expertise, schools, organizations, and countries. This collective causal map is then used to create a new framework for understanding and teaching operations management. This framework can aid instructors in determining which topics should be taught in an operations management course, how these topics might be grouped and sequenced, and the important interrelationships among the topics that should be stressed to students. [source] CuI -Catalyzed Azide,Alkyne Intramolecular i -to-(i+4) Side-Chain-to-Side-Chain Cyclization Promotes the Formation of Helix-Like Secondary StructuresEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 3 2010Mario Scrima Abstract A solid-phase assembly of model peptides derived from human parathyroid hormone-related protein (11,19) containing ,-azido- and ,-yl-,-amino acid residues in positions i and i+4 was cyclised in solution by an intramolecular CuI -catalyzed azide,alkyne 1,3-dipolar Huisgen cycloaddition. These series of heterodetic cyclo-nonapeptides varied in the size of the disubstituted 1,2,3-triazolyl-containing bridge, the location and the orientation of the 1,2,3-triazolyl moiety within the bridge. The 1,2,3-triazolyl moiety, presented at either 1,4- or 4,1-orientation, is flanked by side chains containing 1,4 CH2 groups that result in bridges comprised from 4,7 CH2 groups connecting residues 13 and 17. Comprehensive conformational analysis employing CD, NMR and molecular dynamics reveals the conformational propensities of these heterodetic cyclo-nonapeptides. Cyclo-nonapeptides containing either the 7 methylene bridge (VII and VIII) or the 4 methylene bridge (II) are unstructured in structure-promoting solvent. Cyclo-nonapeptide I in which the 1,4-disubstituted 1,2,3-triazolyl is flanked by 3 and 1 CH2 groups in proximity to the respective residues 13 and 17, is stabilized in a non-canonical structure. All the other heterodetic cyclo-nonapeptides (III,VI) in which the 1,2,3-triazolyl is flanked by a total of 5 or 6 CH2 groups nicely accommodate ,-helical structures and reproduce very closely the helical structure stabilized by the analogous cyclo-nonapeptide in which Lys13 and Asp17 are bridged by the isosteric lactam. These studies suggest that the bioorthogonal i -to-(i+4) side-chain-to-side-chain cyclization via the prototypic "click reaction" offers a new and powerful approach for generating stable helix mimetic structures. [source] Protein tandem repeats , the more perfect, the less structuredFEBS JOURNAL, Issue 12 2010Julien Jorda We analysed the structural properties of protein regions containing arrays of perfect and nearly perfect tandem repeats. Naturally occurring proteins with perfect repeats are practically absent among the proteins with known 3D structures. The great majority of such regions in the Protein Data Bank are found in the proteins designed de novo. The abundance of natural structured proteins with tandem repeats is inversely correlated with the repeat perfection: the chance of finding natural structured proteins in the Protein Data Bank increases with a decrease in the level of repeat perfection. Prediction of intrinsic disorder within the tandem repeats in the SwissProt proteins supports the conclusion that the level of repeat perfection correlates with their tendency to be unstructured. This correlation is valid across the various species and subcellular localizations, although the level of disordered tandem repeats varies significantly between these datasets. On average, in prokaryotes, tandem repeats of cytoplasmic proteins were predicted to be the most structured, whereas in eukaryotes, the most structured portion of the repeats was found in the membrane proteins. Our study supports the hypothesis that, in general, the repeat perfection is a sign of recent evolutionary events rather than of exceptional structural and (or) functional importance of the repeat residues. [source] Folding of epidermal growth factor-like repeats from human tenascin studied through a sequence frame-shift approachFEBS JOURNAL, Issue 21 2004Francesco Zanuttin In order to investigate the factors that determine the correct folding of epidermal growth factor-like (EGF) repeats within a multidomain protein, we prepared a series of six peptides that, taken together, span the sequence of two EGF repeats of human tenascin, a large protein from the extracellular matrix. The peptides were selected by sliding a window of the average length of tenascin EGF repeats over the sequence of EGF repeats 13 and 14. We thus obtained six peptides, EGF-f1 to EGF-f6, that are 33 residues long, contain six cysteines each, and bear a partial overlap in the sequence. While EGF-f1 corresponds to the native EGF-14 repeat, the others are frame-shifted EGF repeats. We carried out the oxidative folding of these peptides in vitro, analyzed the reaction mixtures by acid trapping followed by LC-MS, and isolated some of the resulting products. The oxidative folding of the native EGF-14 peptide is fast, produces a single three-disulfide species with an EGF-like disulfide topology and a marked difference in the RP-HPLC retention time compared with the starting product. On the contrary, frame-shifted peptides fold more slowly and give mixtures of three-disulfide species displaying RP-HPLC retention times that are closer to those of the reduced peptides. In contrast to the native EGF-14, the three-disulfide products that could be isolated are mainly unstructured, as determined by CD and NMR spectroscopy. We conclude that both kinetics and thermodynamics drive the correct pairing of cysteines, and speculate about how cysteine mispairing could trigger disulfide reshuffling in vivo. [source] The stress response protein Gls24 is induced by copper and interacts with the CopZ copper chaperone of Enterococcus hiraeFEMS MICROBIOLOGY LETTERS, Issue 1 2010Jivko V. Stoyanov Abstract Intracellular copper routing in Enterococcus hirae is accomplished by the CopZ copper chaperone. Under copper stress, CopZ donates Cu+ to the CopY repressor, thereby releasing its bound zinc and abolishing repressor,DNA interaction. This in turn induces the expression of the cop operon, which encodes CopY and CopZ, in addition to two copper ATPases, CopA and CopB. To gain further insight into the function of CopZ, the yeast two-hybrid system was used to screen for proteins interacting with the copper chaperone. This led to the identification of Gls24, a member of a family of stress response proteins. Gls24 is part of an operon containing eight genes. The operon was induced by a range of stress conditions, but most notably by copper. Gls24 was overexpressed and purified, and was shown by surface plasmon resonance analysis to also interact with CopZ in vitro. Circular dichroism measurements revealed that Gls24 is partially unstructured. The current findings establish a novel link between Gls24 and copper homeostasis. [source] Fine scale spatial pattern of Pacific sardine (Sardinops sagax) and northern anchovy (Engraulis mordax) eggsFISHERIES OCEANOGRAPHY, Issue 4 2004K. Alexandra Curtis Abstract Pacific sardine (Sardinops sagax) and northern anchovy (Engraulis mordax) eggs exhibited different spatial structure on the scale of 0.75,2.5 km in two egg patches sampled in the Southern California Bight in April 2000. Plankton samples were collected at 4-min intervals with a Continuous Underway Fish Egg Sampler (CUFES) on 5 × 5 km grids centered on surface drifters. Variograms were calculated for sardine and anchovy eggs in Lagrangian coordinates, using abundances of individual developmental stages grouped into daily cohorts. Model variograms for sardine eggs have a low nugget effect, about 10% of the total variance, indicating high autocorrelation between adjacent samples. In contrast, model variograms for anchovy eggs have a high nugget effect of 50,100%, indicating that most of the variance at the scales sampled is spatially unstructured. The difference between observed spatial patterns of sardine and anchovy eggs on this scale may reflect the behavior of the spawning adults: larger, faster, more abundant fish may organize into larger schools with greater structure and mobility that create smoother egg distributions. Size and mobility vary with population size in clupeoids. The current high abundance of sardines and low abundance of anchovy off California agree with the greater autocorrelation of sardine egg samples and the observed tendency for locations of anchovy spawning to be more persistent on the temporal scale of days to weeks. Thus the spatial pattern of eggs and the persistence of spawning areas are suggested to depend on species, population size and age structure, spawning intensity and characteristic physical scales of the spawning habitat. [source] , -Peptide Conjugates: Syntheses and CD and NMR Investigations of ,/, -Chimeric Peptides, of a DPA- , -Decapeptide, and of a PEGylated , -HeptapeptideHELVETICA CHIMICA ACTA, Issue 12 2009James Gardiner Abstract ,3 -Peptides consisting of six, seven, and ten homologated proteinogenic amino acid residues have been attached to an , -heptapeptide (all d- amino acid residues; 4), to a hexaethylene glycol chain (PEGylation; 5c), and to dipicolinic acid (DPA derivative 6), respectively. The conjugation of the , -peptides with the second component was carried out through the N-termini in all three cases. According to NMR analysis (CD3OH solutions), the (M)- 314 -helical structure of the , -peptidic segments was unscathed in all three chimeric compounds (Figs.,2, 4, and 5). The , -peptidic section of the ,/, -peptide was unstructured, and so was the oligoethylene glycol chain in the PEGylated compound. Thus, neither does the appendage influence the , -peptidic secondary structure, nor does the latter cause any order in the attached oligomers to be observed by this method of analysis. A similar conclusion may be drawn from CD spectra (Figs.,1, 3, and 5). These results bode well for the development of delivery systems involving , -peptides. [source] Laminar and turbulent flow calculations through a model human upper airway using unstructured meshesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 12 2007P. Nithiarasu Abstract In this paper, numerical investigation of airflow through a human upper airway is presented using an unstructured-based characteristic-based split (CBS) scheme. The CBS scheme used in the present study employs a fully explicit matrix-free solution procedure along with artificial compressibility. A one equation Spalrat,Allmaras (SA) turbulence model is employed to study low and moderate Reynolds number flows. A detailed discussion of the qualitative and quantitative results is presented. The results show a strong influence of the Reynolds number on the flow pattern and quantities of interest, pressure drop and wall shear stress. It is also apparent that SA model can be employed on unstructured meshes to predict the steady flow with good accuracy. Thus, the novelties of the present paper are: use of the unstructured mesh-based solution algorithm and the successful application of the SA model to a typical human upper airway. Copyright © 2006 John Wiley & Sons, Ltd. [source] Stencil reduction algorithms for the local discontinuous Galerkin methodINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 12 2010Paul E. Castillo Abstract The problem of reducing the stencil of the local discontinuous Galerkin method applied to second-order differential operator is discussed. Heuristic algorithms to minimize the total number of non-zero blocks of the reduced stiffness matrix are presented and tested on a wide variety of unstructured and structured grids in 2D and 3D. Copyright © 2009 John Wiley & Sons, Ltd. [source] Steady and unsteady incompressible flow in a double driven cavity using the artificial compressibility (AC)-based characteristic-based split (CBS) schemeINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 3 2005P. Nithiarasu Abstract In this paper, the explicit characteristic-based split (CBS) scheme has been employed to solve both steady and unsteady flows inside a non-rectangular double driven cavity. This problem is recently suggested as a benchmark problem for incompressible flows. Both unstructured and structured meshes have been employed in the present study to make sure that the predicted results are as close to reality as possible. The results obtained show the existence of steady state at lower Reynolds numbers (,1000) and transient states at higher Reynolds numbers. The flow approaches a turbulent state as the Reynolds number is increased to 10 000. Copyright © 2005 John Wiley & Sons, Ltd. [source] Non-hydrostatic 3D free surface layer-structured finite volume model for short wave propagationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 4 2009L. Cea Abstract In this paper a layer-structured finite volume model for non-hydrostatic 3D environmental free surface flow is presented and applied to several test cases, which involve the computation of gravity waves. The 3D unsteady momentum and mass conservation equations are solved in a collocated grid made of polyhedrons, which are built from a 2D horizontal unstructured mesh, by just adding several horizontal layers. The mesh built in such a way is unstructured in the horizontal plane, but structured in the vertical direction. This procedure simplifies the mesh generation and at the same time it produces a well-oriented mesh for stratified flows, which are common in environmental problems. The model reduces to a 2D depth-averaged shallow water model when one single layer is defined in the mesh. Pressure,velocity coupling is achieved by the Semi-Implicit Method for Pressure-Linked Equations algorithm, using Rhie,Chow interpolation to stabilize the pressure field. An attractive property of the model proposed is the ability to compute the propagation of short waves with a rather coarse vertical discretization. Several test cases are solved in order to show the capabilities and numerical stability of the model, including a rectangular free oscillating basin, a radially symmetric wave, short wave propagation over a 1D bar, solitary wave runup on a vertical wall, and short wave refraction over a 2D shoal. In all the cases the numerical results are compared either with analytical or with experimental data. Copyright © 2008 John Wiley & Sons, Ltd. [source] Some results on the accuracy of an edge-based finite volume formulation for the solution of elliptic problems in non-homogeneous and non-isotropic mediaINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 3 2009Darlan Karlo Elisiário de Carvalho Abstract The numerical simulation of elliptic type problems in strongly heterogeneous and anisotropic media represents a great challenge from mathematical and numerical point of views. The simulation of flows in non-homogeneous and non-isotropic porous media with full tensor diffusion coefficients, which is a common situation associated with the miscible displacement of contaminants in aquifers and the immiscible and incompressible two-phase flow of oil and water in petroleum reservoirs, involves the numerical solution of an elliptic type equation in which the diffusion coefficient can be discontinuous, varying orders of magnitude within short distances. In the present work, we present a vertex-centered edge-based finite volume method (EBFV) with median dual control volumes built over a primal mesh. This formulation is capable of handling the heterogeneous and anisotropic media using structured or unstructured, triangular or quadrilateral meshes. In the EBFV method, the discretization of the diffusion term is performed using a node-centered discretization implemented in two loops over the edges of the primary mesh. This formulation guarantees local conservation for problems with discontinuous coefficients, keeping second-order accuracy for smooth solutions on general triangular and orthogonal quadrilateral meshes. In order to show the convergence behavior of the proposed EBFV procedure, we solve three benchmark problems including full tensor, material heterogeneity and distributed source terms. For these three examples, numerical results compare favorably with others found in literature. A fourth problem, with highly non-smooth solution, has been included showing that the EBFV needs further improvement to formally guarantee monotonic solutions in such cases. Copyright © 2008 John Wiley & Sons, Ltd. [source] CFD-based optimization of aerofoils using radial basis functions for domain element parameterization and mesh deformationINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 8 2008A. M. Morris Abstract A novel domain element shape parameterization method is presented for computational fluid dynamics-based shape optimization. The method is to achieve two aims: (1) provide a generic ,wrap-around' optimization tool that is independent of both flow solver and grid generation package and (2) provide a method that allows high-fidelity aerodynamic optimization of two- and three-dimensional bodies with a low number of design variables. The parameterization technique uses radial basis functions to transfer domain element movements into deformations of the design surface and corresponding aerodynamic mesh, thus allowing total independence from the grid generation package (structured or unstructured). Independence from the flow solver (either inviscid, viscous, aeroelastic) is achieved by obtaining sensitivity information for an advanced gradient-based optimizer (feasible sequential quadratic programming) by finite-differences. Results are presented for two-dimensional aerofoil inverse design and drag optimization problems. Inverse design results demonstrate that a large proportion of the design space is feasible with a relatively low number of design variables using the domain element parameterization. Heavily constrained (in lift, volume, and moment) two-dimensional aerofoil drag optimization has shown that significant improvements over existing designs can be achieved using this method, through the use of various objective functions. Copyright © 2008 John Wiley & Sons, Ltd. [source] Developing implicit pressure-weighted upwinding scheme to calculate steady and unsteady flows on unstructured gridsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 2 2008M. Darbandi Abstract The finite-volume methods normally utilize either simple or complicated mathematical expressions to interpolate the fluxes at the cell faces of their unstructured volumes. Alternatively, we benefit from the advantages of both finite-volume and finite-element methods and estimate the advection terms on the cell faces using an inclusive pressure-weighted upwinding scheme extended on unstructured grids. The present pressure-based method treats the steady and unsteady flows on a collocated grid arrangement. However, to avoid a non-physical spurious pressure field pattern, two mass flux per volume expressions are derived at the cell interfaces. The dual advantages of using an unstructured-based discretization and a pressure-weighted upwinding scheme result in obtaining high accurate solutions with noticeable progress in the performance of the primitive method extended on the structured grids. The accuracy and performance of the extended formulations are demonstrated by solving different standard and benchmark problems. The results show that there are excellent agreements with both benchmark and analytical solutions as well as experimental data. Copyright © 2007 John Wiley & Sons, Ltd. [source] Progressive optimization on unstructured grids using multigrid-aided finite-difference sensitivitiesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 10-11 2005L. A. Catalano Abstract This paper proposes an efficient and robust progressive-optimization procedure, employing cheap, flexible and easy-to-program multigrid-aided finite-differences for the computation of the sensitivity derivatives. The entire approach is combined with an upwind finite-volume method for the Euler and the Navier,Stokes equations on cell-vertex unstructured (triangular) grids, and validated versus the inverse design of an airfoil, under inviscid (subsonic and transonic) and laminar flow conditions. The methodology turns out to be robust and highly efficient, the converged design optimization being obtained in a computational time equal to that required by 11,17 (depending on the application) multigrid flow analyses on the finest grid. Copyright © 2004 John Wiley & Sons, Ltd. [source] Neural network-based adaptive attitude tracking control for flexible spacecraft with unknown high-frequency gainINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 6 2010Qinglei Hu Abstract Adaptive control design using neural networks (a) is investigated for attitude tracking and vibration stabilization of a flexible spacecraft, which is operated at highly nonlinear dynamic regimes. The spacecraft considered consists of a rigid body and two flexible appendages, and it is assumed that the system parameters are unknown and the truncated model of the spacecraft has finite but arbitrary dimension as well, for the purpose of design. Based on this nonlinear model, the derivation of an adaptive control law using neural networks (NNs) is treated, when the dynamics of unstructured and state-dependent nonlinear function are completely unknown. A radial basis function network that is used here for synthesizing the controller and adaptive mechanisms is derived for adjusting the parameters of the network and estimating the unknown parameters. In this derivation, the Nussbaum gain technique is also employed to relax the sign assumption for the high-frequency gain for the neural adaptive control. Moreover, systematic design procedure is developed for the synthesis of adaptive NN tracking control with L2 -gain performance. The resulting closed-loop system is proven to be globally stable by Lyapunov's theory and the effect of the external disturbances and elastic vibrations on the tracking error can be attenuated to the prescribed level by appropriately choosing the design parameters. Numerical simulations are performed to show that attitude tracking control and vibration suppression are accomplished in spite of the presence of disturbance torque/parameter uncertainty. Copyright © 2009 John Wiley & Sons, Ltd. [source] Making Art, Teaching Art, Learning Art: Exploring the Concept of the Artist TeacherINTERNATIONAL JOURNAL OF ART & DESIGN EDUCATION, Issue 2 2010James Hall The article explores the concept of the artist teacher, drawing upon an overview of relevant literature and two related pieces of research: the first investigated practices within the Artist Teacher Scheme (ATS); the second sought to understand the perceptions of practice-based coursework in an MA Art Education programme at Roehampton University in London. Commonalities and differences between the perceptions and understandings of artist teachers (including masters' students), their tutors and gallery educators were explored. The data for each piece of research were collected through unstructured, open-ended interviews. A significant reflexive and autobiographical dimension for the research was motivated by my own identity as an artist teacher, and by the exploration of reflective practice as a potential framework for realising and sustaining an artist teacher identity and practice. The research concluded that connections between art practice and teaching are complex, diverse, difficult to articulate, challenging to implement and do not easily lend themselves to simple impact measurement. The ATS operates in a context that includes languages, cultures and identities from frameworks in education and art that can be both complementary and oppositional. Artist teachers need to develop skills of negotiation through which they can articulate and continuously reappraise their art practice and, at an appropriate stage, use that practice to inform their teaching. [source] Agents that acquire negotiation strategies using a game theoretic learning theoryINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 1 2006Norberto Eiji Nawa Automated negotiation systems and real-world negotiation situations have many aspects in common. Time is a relevant factor for all parties; information about preferences is private, and there is no interest in having it disclosed; negotiators learn about the opponents and try to enhance their strategies while interacting with one another. Experiments were performed with computational agents employing a learning algorithm based on the ideas of the Experience-Weighted Attraction theory of learning in games, which has been shown to model well human behavior observed in experimental settings. Negotiation strategies are acquired as the agents play bargaining games against one another. The strategies determine the agents' behaviors: how much they offer to the opponent, when they make offers, and the conditions for accepting an offer. The results show that the learning agents were able to acquire sensible strategies even from the most unstructured and dynamic environments. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 5,39, 2006. [source] Clinicians' Views on Reproductive Needs and Services for Teens With Negative Pregnancy TestsJOURNAL FOR SPECIALISTS IN PEDIATRIC NURSING, Issue 2 2004Alison Moriarty Daley MSN ISSUES AND PURPOSE To explore services available to adolescent girls at the time of the negative pregnancy test (NPT) in an urban community. DESIGN AND METHODS Clinicans focus groups were conducted to identify the needs of adolescents at the time of a NPT result. RESULTS Teens access care in a variety of ways, services provided at the time of a NPT were agency and clinical dependent, and strategies for follow-up care often were unstructured. Few services were available for parents or partners. Barriers included difficulty communicating with agencies, lack of staff trained to work with adolescents, and time/financial constraints. CONCLUSION Adolescents need comprehensive, teen-friendly reproductive care at the time of a NPT results. [source] The DARPA LAGR program: Goals, challenges, methodology, and phase I resultsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 11-12 2006L. D. Jackel The DARPA Learning Applied to Ground Vehicles (LAGR) program is accelerating progress in autonomous, perception-based, off-road navigation in unmanned ground vehicles (UGVs) by incorporating learned behaviors. In addition, the program is using passive optical systems to accomplish long-range scene analysis. By combining long-range perception with learned behavior, LAGR expects to make a qualitative break with the myopic, brittle behavior that characterizes most UGV autonomous navigation in unstructured environments. The very nature of testing navigation in unstructured, off-road environments makes accurate, objective measurement of progress a challenging task. While no absolute measure of performance has been defined by LAGR, the Government Team managing the program has created a relative measure: the Government Team tests navigation software by comparing its effectiveness to that of fixed, but state-of-the-art, navigation software running on a standardized vehicle on a series of varied test courses. Starting in March 2005, eight performers have been submitting navigation code for Government testing on such a standardized Government vehicle. As this text is being written, several teams have already demonstrated leaps in performance. In this paper we report observations on the state of the art in autonomous, off-road UGV navigation, we explain how LAGR intends to change current methods, we discuss the challenges we face in implementing technical aspects of the program, we describe early results, and we suggest where major opportunities for breakthroughs exist as LAGR progresses. © 2007 Wiley Periodicals, Inc. [source] The visual compass: Performance and limitations of an appearance-based methodJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2006Frédéric Labrosse In this article we present an algorithm to estimate the orientation of a robot relative to an orientation specified at the beginning of the process. This is done by computing the rotation of the robot between successive panoramic images, grabbed on the robot while it moves, using a subsymbolic method to match the images. The context of the work is simultaneous localization and mapping (SLAM) in unstructured and unmodified environments. As such, very few assumptions are made about the environment and the robot's displacement. The algorithm's performance depends on the value of a number of parameters being determined to provide overall good performance of the system. The performance is evaluated in different situations (trajectories and environments) with the same parameters and the results show that the method performs adequately for its intended use. In particular, the error is shown to be drifting slowly, in fact much slower than unprocessed inertial sensors, thus only requiring infrequent realignment, for example, when relocalizing in a topological map. Limitations of the proposed methods are also shown and discussed. © 2006 Wiley Periodicals, Inc. [source] Mobile robot motion estimation by 2D scan matching with genetic and iterative closest point algorithmsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 1 2006Jorge L. Martínez The paper reports on mobile robot motion estimation based on matching points from successive two-dimensional (2D) laser scans. This ego-motion approach is well suited to unstructured and dynamic environments because it directly uses raw laser points rather than extracted features. We have analyzed the application of two methods that are very different in essence: (i) A 2D version of iterative closest point (ICP), which is widely used for surface registration; (ii) a genetic algorithm (GA), which is a novel approach for this kind of problem. Their performance in terms of real-time applicability and accuracy has been compared in outdoor experiments with nonstop motion under diverse realistic navigation conditions. Based on this analysis, we propose a hybrid GA-ICP algorithm that combines the best characteristics of these pure methods. The experiments have been carried out with the tracked mobile robot Auriga-, and an on-board 2D laser scanner. © 2006 Wiley Periodicals, Inc. [source] An affordable modular mobile robotic platform with fuzzy logic control and evolutionary artificial neural networksJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 8 2004Maurice Tedder Autonomous robotics projects encompass the rich nature of integrated systems that includes mechanical, electrical, and computational software components. The availability of smaller and cheaper hardware components has helped make possible a new dimension in operational autonomy. This paper describes a mobile robotic platform consisting of several integrated modules including a laptop computer that serves as the main control module, microcontroller-based motion control module, a vision processing module, a sensor interface module, and a navigation module. The laptop computer module contains the main software development environment with a user interface to access and control all other modules. Programming language independence is achieved by using standard input/output computer interfaces including RS-232 serial port, USB, networking, audio input and output, and parallel port devices. However, with the same hardware technology available to all, the distinguishing factor in most cases for intelligent systems becomes the software design. The software for autonomous robots must intelligently control the hardware so that it functions in unstructured, dynamic, and uncertain environments while maintaining an autonomous adaptability. This paper describes how we introduced fuzzy logic control to one robot platform in order to solve the 2003 Intelligent Ground Vehicle Competition (IGVC) Autonomous Challenge problem. This paper also describes the introduction of hybrid software design that utilizes Fuzzy Evolutionary Artificial Neural Network techniques. In this design, rather than using a control program that is directly coded, the robot's artificial neural net is first trained with a training data set using evolutionary optimization techniques to adjust weight values between neurons. The trained neural network with a weight average defuzzification method was able to make correct decisions to unseen vision patterns for the IGVC Autonomous Challenge. A comparison of the Lawrence Technological University robot designs and the design of the other competing schools shows that our platforms were the most affordable robot systems to use as tools for computer science and engineering education. © 2004 Wiley Periodicals, Inc. [source] Macrophage aggregates in gilthead sea bream fed copper, iron and zinc enriched dietsJOURNAL OF FISH BIOLOGY, Issue 2 2000M. Manera Gilthead sea bream Sparus aurata from consecutive year classes (0+ and 1+) and from the same parent stock were fed four diets, three of which were fortified with copper, iron and zinc. Concentrations of these elements were little affected by the diet. Hepatic, renal and splenic tissues sections were examined to detect the influence of the diet on the number and morphology of macrophage aggregates (MAs); in particular their structure was examined in the spleen. Three different types of MAs were detected: (1) unstructured, (2) partially structured and scarcely defined and (3) fully structured and well defined. Melanin was the most abundant pigment in the pigmented macrophages which form MAs and the amount of this pigment was influenced by season. Ferritin, in contrast with previous data obtained in other fish species, was more abundant in renal than in splenic MAs. Significant differences in splenic MA numbers among fish fed different diets and among different periods of the year were detected. The results suggest that a polyfactorial regulation could act on the splenic MA number in gilthead sea bream. [source] Managing discontinuity in academic medical centers: Strategies for a safe and effective resident sign-outJOURNAL OF HOSPITAL MEDICINE, Issue 4 2006Arpana R. Vidyarthi MD Abstract BACKGROUND Restrictions in the hours residents can be on duty have resulted in increased sign-outs, that is, transfer of patient care information and responsibility from one physician to a cross-coverage physician, leading to discontinuity in patient care. This sign-out process, which occurs primarily in the inpatient setting, traditionally has been informal, unstructured, and idiosyncratic. Although studies show that discontinuity may be harmful to patients, this is little data to assist residency programs in redesigning systems to improve sign-out and manage the discontinuity. PURPOSE This article reviews the relevant medical literature, current practices in non,health professions in managing discontinuity, and summarizes the existing practice and experiences at 3 academic internal medicine hospitalist-based programs. CONCLUSIONS We provide recommendations and strategies for best practices to design safe and effective sign-out systems for residents that may also be useful to hospitalists working in academic and community settings. Journal of Hospital Medicine 2006;1:257,266. © 2006 Society of Hospital Medicine. [source] Solution structure of LC5, the CCR5- derived peptide for HIV-1 inhibitionJOURNAL OF PEPTIDE SCIENCE, Issue 4 2010Kazuhide Miyamoto Abstract The synthetic peptide fragment (LC5: LRCRNEKKRHRAVRLIFTI) inhibits human immunodeficiency virus type 1 (HIV-1) infection of MT-4 cells. In this study, the solution structure of LC5 in SDS micelles was elucidated by using the standard 1H two-dimensional NMR spectroscopic method along with circular dichroism and fluorescence quenching. The peptide adopts a helical structure in the C-terminal region (residues 13,16), whereas the N-terminal part remains unstructured. The importance of Phe17 in maintaining the structure of LC5 was demonstrated by replacing Phe17 with Ala, which resulted in the dramatic conformational change of LC5. The solution structure of LC5 elucidated in the present work provides a basis for further study of the mechanism of the inhibition of HIV-1 infection. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd. [source] An Exploratory Qualitative Study Examining the Social and Psychological Processes Involved in Regular Dental AttendanceJOURNAL OF PUBLIC HEALTH DENTISTRY, Issue 1 2000Barry J. Gibson BSc, MMedSc Abstract Objective: This study aimed to provide a description of the psychosocial process involved in regular dental attendance. Methods: The study design was a qualitative cross-sectional study using unstructured and semistructured interviews and observations of regular dental visits. The study participants included 12 men and 18 women attending general dental practices and six men and four women attending an emergency dental service. The data were systematically recorded and subjected to line-by-line grounded theory coding around the main concerns of those attending the dentist. Results: The main concern of those attending for a regular dental visit was checking their oral health. The six-month recall was conceptualized as a checking cycle in six phases: recalling, responding, inducing (i), waiting, inducing (ii), and telling. The possible outcomes of the cycle were maintaining oral health, sustaining oral health, and a further checking cycle. Variations in checking cycles resulted from reordering and normalizing pressures within participants' lifestyles. Conclusions: The findings of this study suggest that people's patterns of dental attendance are similar to those of other chronic illnesses. An understanding of the dynamic psychosocial processes involved in frequent dental attendance may be achieved when further research into this phenomenon is conducted. [source] Numerical simulation of a permittivity probe for measuring the electric properties of planetary regolith and application to the near-surface region of asteroids and cometsMETEORITICS & PLANETARY SCIENCE, Issue 6 2008Klaus SPITZER Our simulation techniques aim at accompanying hardware development and conducting virtual experiments, e.g., to assess the response of arbitrary heterogeneous conductivity and permittivity distributions or to scrutinize possibilities for spatial reconstruction methods using inverse schemes. In a first step, we have developed a finite element simulation code on the basis of unstructured, adaptive triangular grids for arbitrary two-dimensional axisymmetric distributions of conductivity and permittivity. The code is able to take into account the spatial geometry of the probe and allows for possible inductive effects. In previous studies, the non-inductive approach has been used to convert potential and phase data into apparent material properties. By our simulations, we have shown that this approach is valid for the frequency range from 102 Hz to 107 Hz and electric conductivities of 10,8 S/m that are typical for the near-surface region of asteroids and comets composed of chondritic materials and/or frozen volatiles such as H2O and CO2 ice. We prove the accuracy of our code to be better than 10%, using mixed types of boundary conditions and present a simulated vertical log through a horizontally stratified subsurface layer as a representative example of a heterogeneous distribution of the electrical properties. Resolution studies for the given electrode separation reveal that the material parameters of layers having thicknesses of less than about half the electrode spread are not reconstructible if only apparent quantities are considered. Therefore, spatial distributions of the complex sensitivity are presented having in mind a future data inversion concept that will permit the multi-dimensional reconstruction of material parameters in heterogeneous environments. [source] | |||||||||||||||||||||||||