Key Aspects (key + aspect)

Distribution by Scientific Domains
Distribution within Medical Sciences

Kinds of Key Aspects

  • several key aspect

  • Selected Abstracts


    EDUCATIONAL THEORY, Issue 1 2009
    Carola Conle
    In this essay, Carola Conle and Michael deBeyer describe their efforts to find a conceptual approach and methodology for the appraisal of the ethos of experiential narratives presented in a particular curriculum context. The language of "implied authorship,""the patterning of desire," and "friendships offered and received," first introduced by Wayne Booth, is elaborated through data from narrative presentations given by local heroes to students. Appraisals seemed possible when a narrative could be placed on Booth's "scales of friendship" and when the rational qualities of experiential narratives were considered. In addition, data needed to be available in which students' experiential encounters with the narratives could be seen as occasions where, during such moments of encounter, feelings and desires were created, memories were activated, and events and actions in a narrative were vicariously experienced through those activated phenomena. The authors offer a potential framework for future appraisals. [source]

    Key Aspects of Psychological Change in Residents of a Prison Therapeutic Community: A Focus Group Approach

    Residents identified change as a process comprising variability, gradual movement and differential paces. The process was seen to involve self-referential properties, interpersonal facets and challenges. Residents distinguished two significant change events: identifying aspects of the unknown and openness to receive help. Support is given to focus group methodology as a way of offering novel insights into experience of a TC as a process-orientated model of change, taking into account individual aspects and underlying facets of change. [source]

    An extended finite element method with analytical enrichment for cohesive crack modeling

    James V. CoxArticle first published online: 28 NOV 200
    Abstract A recent approach to fracture modeling has combined the extended finite element method (XFEM) with cohesive zone models. Most studies have used simplified enrichment functions to represent the strong discontinuity but have lacked an analytical basis to represent the displacement gradients in the vicinity of the cohesive crack. In this study enrichment functions based upon an existing analytical investigation of the cohesive crack problem are proposed. These functions have the potential of representing displacement gradients in the vicinity of the cohesive crack and allow the crack to incrementally advance across each element. Key aspects of the corresponding numerical formulation and enrichment functions are discussed. A parameter study for a simple mode I model problem is presented to evaluate if quasi-static crack propagation can be accurately followed with the proposed formulation. The effects of mesh refinement and mesh orientation are considered. Propagation of the cohesive zone tip and crack tip, time variation of the cohesive zone length, and crack profiles are examined. The analysis results indicate that the analytically based enrichment functions can accurately track the cohesive crack propagation of a mode I crack independent of mesh orientation. A mixed mode example further demonstrates the potential of the formulation. Copyright © 2008 John Wiley & Sons, Ltd. [source]

    The Effectiveness of a Community-Based Program for Reducing the Incidence of Falls in the Elderly: A Randomized Trial

    Lindy Clemson BAppSc(OT), MAppSc(OT)
    Objectives: To test whether Stepping On, a multifaceted community-based program using a small-group learning environment, is effective in reducing falls in at-risk people living at home. Design: A randomized trial with subjects followed for 14 months. Setting: The interventions were conducted in community venues, with a follow-up home visit. Participants: Three hundred ten community residents aged 70 and older who had had a fall in the previous 12 months or were concerned about falling. Intervention: The Stepping On program aims to improve fall self-efficacy, encourage behavioral change, and reduce falls. Key aspects of the program are improving lower-limb balance and strength, improving home and community environmental and behavioral safety, encouraging regular visual screening, making adaptations to low vision, and encouraging medication review. Two-hour sessions were conducted weekly for 7 weeks, with a follow-up occupational therapy home visit. Measurements: The primary outcome measure was falls, ascertained using a monthly calendar mailed by each participant. Results: The intervention group experienced a 31% reduction in falls (relative risk (RR)=0.69, 95% confidence interval (CI)=0.50,0.96; P=.025). This was a clinically meaningful result demonstrating that the Stepping On program was effective for community-residing elderly people. Secondary analysis of subgroups showed that it was particularly effective for men (n=80; RR=0.32, 95% CI=0.17,0.59). Conclusion: The results of this study renew attention to the idea that cognitive-behavioral learning in a small-group environment can reduce falls. Stepping On offers a successful fall-prevention option. [source]

    Clinical teachers' approaches to nursing

    Helen Forbes
    Aims and objectives., The aim of the study was to investigate clinical teachers' experiences of nursing and clinical teaching of undergraduate university students. This article reports on clinical teachers' approaches to nursing, which is one part of that study. Background., A lack of knowledge and understanding exists about how clinical teachers approach nursing. There is a likely relationship between approaches to nursing and what is focused on when teaching undergraduate nursing students in the clinical setting. It is therefore important to understand the variation in how clinical teachers approach nursing. Design., Phenomenography. Method., Semi-structured interviews of 20 practicing nurses currently employed as clinical teachers from a range of Australian universities were conducted. Data were analysed using a phenomenographic approach. Results., Key aspects of variation in clinical teacher approaches to nursing were identified. The results suggest that clinical teachers approach nursing in one of two ways, either a patient-focused approach or a nurse-focused approach. The research findings extend knowledge that will assist with preparation and support of clinical teachers. Conclusion., Knowledge of the different approaches to nursing provides a structure for helping clinical teachers increase their awareness of both their approach to nursing and the implications for their nursing and teaching. Relevance to clinical practice., Awareness of complex approaches to nursing may be required for multidisciplinary care. [source]

    When Production and Consumption Meet: Cultural Contradictions and the Enchanting Myth of Customer Sovereignty

    Marek Korczynski
    ABSTRACT The central cultural contradiction of capitalism, argued Bell some 25 years ago, was the existence of rationalized, disciplined production alongside free and hedonistic consumption. This paper argues that this thesis, although overstated, has resonance within contemporary capitalism. The paper then considers the question of how this contradiction is managed when production and consumption meet directly within the service interaction. On the production-side rationalization is joined by customer-orientation, and on the consumption-side management promotes consumption of the enchanting myth of sovereignty. Here the customer is meant to experience a sense of being sovereign. At the same time the space is created for the customer to be, potentially, substantively directed and influenced to follow the requirements that flow from the rationalized elements of production. Key aspects of the service interaction, including the menu and its presentation, the display of empathy and aesthetic labour, and the use of naming within the service interaction, are analysed in terms of the promotion of the enchanting myth of sovereignty. Consumption, however, is a fragile process, and remains, to an important degree, ,unmanageable'. The analysis, therefore, also examines how the promotion of the enchanting myth of sovereignty systematically creates the conditions for the myth's negation. [source]

    Constitutive activation of MAPK cascade in acute quadriplegic myopathy

    ANNALS OF NEUROLOGY, Issue 2 2004
    Simone Di Giovanni MD
    Acute quadriplegic myopathy (AQM; also called "critical illness myopathy") shows acute muscle wasting and weakness and is experienced by some patients with severe systemic illness, often associated with administration of corticosteroids and/or neuroblocking agents. Key aspects of AQM include muscle atrophy and myofilament loss. Although these features are shared with neurogenic atrophy, myogenic atrophy in AQM appears mechanistically distinct from neurogenic atrophy. Using muscle biopsies from AQM, neurogenic atrophy, and normal controls, we show that both myogenic and neurogenic atrophy share induction of myofiber-specific ubiquitin/proteosome pathways (eg, atrogin-1). However, AQM patient muscle showed a specific strong induction of transforming growth factor (TGF),,/MAPK pathways. Atrophic AQM myofibers showed coexpression of TGF-, receptors, p38 MAPK, c-jun, and c-myc, including phosphorylated active forms, and these same fibers showed apoptotic features. Our data suggest a model of AQM pathogenesis in which stress stimuli (sepsis, corticosteroids, pH imbalance, osmotic imbalance) converge on the TGF-, pathway in myofibers. The acute stimulation of the TGF-,/MAPK pathway, coupled with the inactivity-induced atrogin-1/proteosome pathway, leads to the acute muscle loss seen in AQM patients. Ann Neurol 2004 [source]

    Incorporating a collaborative web-based virtual laboratory in an undergraduate bioinformatics course

    David Weisman
    Abstract Face-to-face bioinformatics courses commonly include a weekly, in-person computer lab to facilitate active learning, reinforce conceptual material, and teach practical skills. Similarly, fully-online bioinformatics courses employ hands-on exercises to achieve these outcomes, although students typically perform this work offsite. Combining a face-to-face lecture course with a web-based virtual laboratory presents new opportunities for collaborative learning of the conceptual material, and for fostering peer support of technical bioinformatics questions. To explore this combination, an in-person lecture-only undergraduate bioinformatics course was augmented with a remote web-based laboratory, and tested with a large class. This study hypothesized that the collaborative virtual lab would foster active learning and peer support, and tested this hypothesis by conducting a student survey near the end of the semester. Respondents broadly reported strong benefits from the online laboratory, and strong benefits from peer-provided technical support. In comparison with traditional in-person teaching labs, students preferred the virtual lab by a factor of two. Key aspects of the course architecture and design are described to encourage further experimentation in teaching collaborative online bioinformatics laboratories. [source]

    How can you help organizations change to meet the corporate responsibility agenda?

    David Lyon
    As corporate responsibility (CR) has developed over the past decade, companies have developed and communicated their formal values relating to environment, employees, stakeholders and governance through public statements. Many of these companies have produced formal reports covering their performance on environmental and social issues. Continued improvement and delivery of commitments depends on buy-in not just from senior management (and the CR manager), but from managers and staff across the organization. This is only possible if there is a culture that is supportive of corporate responsibility. One key aspect of making this change is understanding how the company's culture affects corporate responsibility performance. This paper discusses some areas of organizational culture that affect CR performance including rewards and recognition, learning and managing change, awareness and involvement, questioning culture and flexibility underpinned by mutual respect. It also provides an overview of our approach for assessing and fostering a supportive culture. This is based on working with clients to manage their licence to operate in addition to extensive experience in innovation culture and safety culture. Copyright © 2004 John Wiley & Sons, Ltd and ERP Environment. [source]

    Clinical utility of CD23 and FMC7 antigen coexistent expression in B-cell lymphoproliferative disorder subclassification

    CYTOMETRY, Issue 1 2002
    Ejaz Ahmad
    Abstract Background: CD23 and FMC7 are normal B-cell antigens utilized during diagnostic immunophenotyping of suspected lymphoproliferative disorders. However, the diagnostic utility of coexistent antigenic expression patterns with simultaneous two-color staining and flow cytometric analysis has not been studied extensively. Methods: Using multiparameter flow cytometry, we evaluated the expression pattern of FMC7 and CD23 in 218 cases of B-cell lymphoma from blood and bone marrow specimens. Results: The CD23(+)/FMC7(-) pattern was the most common pattern in patients with chronic lymphocytic leukemia and related variants. The widest variation of patterns was found in patients with follicular cell lymphoma, large cell lymphoma, and Waldenström's macroglobulinemia, a lymphoplasmacytoid disorder, although most cases expressed the CD23-/FMC7(+) pattern. The CD23 and FMC7 antigen, along with the CD5 coexpression pattern, provides critical adjunctive data. These data allow accurate classification of the majority of cases, thereby providing a key aspect of a reliable diagnostic algorithm. The CD23 and FMC7 antigen expression pattern, along with selected other antigens, was predictive of subtypes in >95% of lymphoproliferative cases and narrowed the differential diagnosis in the remaining cases. Conclusion: The flow cytometric CD23/FMC7 expression pattern achieved by multicolor immunophenotyping facilitates accurate and reproducible classification of B-cell lymphomas and has diagnostic utility. Cytometry (Clin. Cytometry) 50:1,7, 2002. © 2002 Wiley-Liss, Inc. [source]

    Self-organized and highly ordered domain structures within swarms of Myxococcus xanthus

    CYTOSKELETON, Issue 3 2006
    Andrew E. Pelling
    Abstract Coordinated group movement (swarming) is a key aspect of Myxococcusxanthus' social behavior. Here we report observation of domain structures formed by multiple cells within large three-dimensional swarming groups grown on amorphous glass substrates, using the atomic force microscope (AFM). Novel analyses revealed that ,90% of the wild type swarms displayed some form of preferential cell alignment. In contrast, cells with mutations in the social and adventurous motility systems displayed a distinct lack of cell alignment. Video microscopy observations of domain features of in vivo swarming M.xanthus cells were also consistent with the AFM data. The results presented here reveal that unique domain formation within swarms of wild type cells is a biologically driven process requiring the social and adventurous motility systems and is not a statistical phenomenon or thermodynamic process arising from liquid crystal behavior. Cell Motil. Cytoskeleton 63, 2006. © 2006 Wiley-Liss, Inc. [source]

    Steering the brand in the auto industry

    Anne Asensio
    At General Motors, the goal is to give each automotive line a distinctive brand character. In this interview, Anne Asensio discusses how she and her design colleagues contribute to this effort. From contour to features, these elements are used to reinforce brand character and build an emotional bond with consumers. It is intense and exciting work in which quality,from conception to execution,is a key aspect of success. [source]

    Plant invaders and their novel natural enemies: who is naïve?

    ECOLOGY LETTERS, Issue 2 2009
    Koen J. F. Verhoeven
    Abstract Introduced exotic species encounter a wide range of non-coevolved enemies and competitors in their new range. Evolutionary novelty is a key aspect of these interactions, but who benefits from novelty: the exotic species or their new antagonists? Paradoxically, the novelty argument has been used to explain both the release from and the suppression by natural enemies. We argue that this paradox can be solved by considering underlying interaction mechanisms. Using plant defenses as a model, we argue that mismatches between plant and enemy interaction traits can enhance plant invasiveness in the case of toxin-based defenses, whereas invasiveness is counteracted by mismatches in recognition-based defenses and selective foraging of generalist herbivores on plants with rare toxins. We propose that a mechanistic understanding of ecological mismatches can help to explain and predict when evolutionary novelty will enhance or suppress exotic plant invasiveness. This knowledge may also enhance our understanding of plant abundance following range expansion, or during species replacements along successional stages. [source]

    A Quantified Ethogram for Oviposition in Triturus Newts: Description and Comparison of T. helveticus and T. vulgaris

    ETHOLOGY, Issue 4 2005
    Karen M. Norris
    Female newts of the genus Triturus deposit and wrap their eggs individually in the submerged leaves of aquatic macrophytes. Although this behaviour has previously been described, the different elements of the oviposition process have not been fully characterized nor any attempt made to quantify the behavioural elements. The study examined the oviposition behaviour of the two similarly sized species, Triturus helveticus and T. vulgaris on a standardized substrate macrophyte, Rorippa nasturtium,aquaticum. Continuous focal sampling was used to develop a baseline of discrete behavioural elements enabling quantification and comparison of oviposition behaviour between the two species. The results showed that the same pattern of elements was followed for each egg laid and the same key elements of the process were present in each newt species. Although these are broadly similar in size, there were striking differences in certain aspects of the oviposition sequence between the two species. Key findings were that leaf sniffing and leaf flexing and a measure of the duration of ovipositing were all significantly greater in females of T. helveticus and females of T. vulgaris laid significantly more eggs than those of T. helveticus in a standard observation period. The work presented here defines a baseline ethogram and shows how it can be used to reveal quantifiable differences in closely related species. This demonstrates its value in furthering our understanding of oviposition , a key aspect of female behaviour currently understudied in Triturus behavioural ecology, despite its intrinsic interest and value in understanding recruitment and maintenance of populations. [source]


    EVOLUTION, Issue 5 2010
    Sarah R. Pryke
    Assortative mating is a key aspect in the speciation process because it is important for both initial divergence and maintenance of distinct species. However, it remains a challenge to explain how assortative mating evolves when diverging populations are undergoing gene flow (e.g., during hybridization). Here I experimentally test how assortative mating is maintained with frequent gene flow between diverged head-color morphs of the Gouldian finch (Erythrura gouldiae). Contrary to the predominant view on the development of sexual preferences in birds, cross-fostered offspring did not imprint on the phenotype of their conspecific (red or black morphs) or heterospecific (Bengalese finch) foster parents. Instead, the mating preferences of F1 and F2 intermorph-hybrids are consistent with inheritance on the Z chromosomes, which are also the location for genes controlling color expression and the genes causing low fitness of intermorph-hybrids. Genetic associations between color signal and preference loci on the sex chromosomes may prevent recombination from breaking down these associations when the morphs interbreed, helping to maintain assortative mating in the face of gene flow. Although sex linkage of reproductively isolating traits is theoretically expected to promote speciation, social and ecological constraints may enforce frequent interbreeding between the morphs, thus preventing complete reproductive isolation. [source]


    Pauline Allen
    Introducing market-like structures to public services is a key aspect of New Public Management. The restructuring of the NHS into an internal market of the 1990s is an example. Recent policies have further developed this notion. A new aspect of the restructuring is a focus on increasing the diversity of types of provider of healthcare organisations. The objectives of the restructuring policy entailing the increase in supply side diversity are examined, and the challenges raised by these changes are discussed. It is argued that the government is too optimistic about the benefits, and insufficiently concerned about possible undesirable consequences. [source]

    Attending to the world: competition, cooperation and connectivity in the World City network

    GLOBAL NETWORKS, Issue 2 2002
    J. V. Beaverstock
    World Cities are acknowledged to be a key aspect of globalization. In many accounts, these cities are depicted as rivals in a global marketplace, their economic success a result of their competitive advantage. However, what has not been fully acknowledged is their connectivity and, in addition, the time and effort taken by specific ,attendants' to produce the World City network. Accordingly, this article aims to advance understanding of World City network formation by developing a conceptual model that focuses on four major attendants (firms, sectors, cities and states) that enact network formation through two nexuses ,,city-firm' and ,statesector', and two communities ,,cities within states' and ,firms within sectors'. The utility of this model is demonstrated by drawing upon interviews conducted in offices of 39 advanced producer service firms in banking and law. These interviews were undertaken in three World Cities (London, New York and Singapore) in the wake of the East Asian financial crisis, an event that challenged the consistency of the World City network. Showing how attendants sought to maintain and transform the World City network at this key moment of crisis, we conclude that studies of city competitiveness ultimately need to focus on the cooperative work that sustains global networks. [source]

    A micromechanical study of rolling and sliding contacts in assemblies of oval granules

    Hossein M. Shodja
    Abstract The evolution of the microstructure of an assembly of cohesionless granular materials with associated pores, which carry the overall applied stresses through frictional contacts is a complex phenomenon. The macroscopic flow of such materials take place by the virtue of the relative rolling and sliding of the grains on the micro-scale. A new discrete element method for biaxial compression simulations of random assemblies of oval particles with mixed sizes is introduced. During the course of deformation, the new positions of the grains are determined by employing the static equilibrium equations. A key aspect of the method is that, it is formulated for ellipse cross-sectional particles, hence desirable inherent anisotropies are possible. A robust algorithm for the determination of the contact points between neighbouring grains is given. Employing the present methodology, many aspects of the behaviour of two-dimensional assemblies of oval cross-sectional rods have been successfully addressed. The effects of initial void ratio, interparticle friction angle, aspect ratio, and bedding angle on the rolling and sliding contacts are examined. The distribution of normals to the rolling and sliding contacts have different patterns and are concentrated along directions, which are approximately perpendicular to one another. On the other hand, the distribution of all contact normals (combined rolling and sliding) are close to that of rolling contacts, which confirm that rolling is the dominant mechanism. This phenomenon becomes more pronounced for higher intergranular friction angle. Characteristics of the rolling and sliding contacts are also discussed in the context of the force angle, which is the inclination of contact force with respect to the contact normal. Copyright © 2003 John Wiley & Sons, Ltd. [source]

    Strong and weak arbitrary discontinuities in spectral finite elements

    A. Legay
    Abstract Methods for constructing arbitrary discontinuities within spectral finite elements are described and studied. We use the concept of the eXtended Finite Element Method (XFEM), which introduces the discontinuity through a local partition of unity, so there is no requirement for the mesh to be aligned with the discontinuities. A key aspect of the implementation of this method is the treatment of the blending elements adjacent to the local partition of unity. We found that a partition constructed from spectral functions one order lower than the continuous approximation is optimal and no special treatment is needed for higher order elements. For the quadrature of the Galerkin weak form, since the integrand is discontinuous, we use a strategy of subdividing the discontinuous elements into 6- and 10-node triangles; the order of the element depends on the order of the spectral method for curved discontinuities. Several numerical examples are solved to examine the accuracy of the methods. For straight discontinuities, we achieved the optimal convergence rate of the spectral element. For the curved discontinuity, the convergence rate in the energy norm error is suboptimal. We attribute the suboptimality to the approximations in the quadrature scheme. We also found that modification of the adjacent elements is only needed for lower order spectral elements. Copyright © 2005 John Wiley & Sons, Ltd. [source]

    Dry spots and wet spots in the Andean hotspot

    Timothy J. Killeen
    Abstract Aim, To explain the relationship between topography, prevailing winds and precipitation in order to identify regions with contrasting precipitation regimes and then compare floristic similarity among regions in the context of climate change. Location, Eastern slope of the tropical Andes, South America. Methods, We used information sources in the public domain to identify the relationship between geology, topography, prevailing wind patterns and precipitation. Areas with contrasting precipitation regimes were identified and compared for their floristic similarity. Results, We identify spatially separate super-humid, humid and relatively dry regions on the eastern slope of the Andes and show how they are formed by the interaction of prevailing winds, diurnally varying atmospheric circulations and the local topography of the Andes. One key aspect related to the formation of these climatically distinct regions is the South American low-level jet (SALLJ), a relatively steady wind gyre that flows pole-ward along the eastern slopes of the Andes and is part of the gyre associated with the Atlantic trade winds that cross the Amazon Basin. The strongest winds of the SALLJ occur near the ,elbow of the Andes' at 18° S. Super-humid regions with mean annual precipitation greater than 3500 mm, are associated with a ,favourable' combination of topography, wind-flow orientation and local air circulation that favours ascent at certain hours of the day. Much drier regions, with mean annual precipitation less than 1500 mm, are associated with ,unfavourable' topographic orientation with respect to the mean winds and areas of reduced cloudiness produced by local breezes that moderate the cloudiness. We show the distribution of satellite-estimated frequency of cloudiness and offer hypotheses to explain the occurrence of these patterns and to explain regions of anomalously low precipitation in Bolivia and northern Peru. Floristic analysis shows that overall similarity among all circumscribed regions of this study is low; however, similarity among super-humid and humid regions is greater when compared with similarity among dry regions. Spatially separate areas with humid and super-humid precipitation regimes show similarity gradients that are correlated with latitude (proximity) and precipitation. Main conclusions, The distribution of precipitation on the eastern slope of the Andes is not simply correlated with latitude, as is often assumed, but is the result of the interplay between wind and topography. Understanding the phenomena responsible for producing the observed precipitation patterns is important for mapping and modelling biodiversity, as well as for interpreting both past and future climate scenarios and the impact of climate change on biodiversity. Super-humid and dry regions have topographic characteristics that contribute to local climatic stability and may represent ancestral refugia for biodiversity; these regions are a conservation priority due to their unique climatic characteristics and the biodiversity associated with those characteristics. [source]

    Understanding immune cell trafficking patterns via in vivo bioluminescence imaging

    Stefanie Mandl
    Abstract Cell migration is a key aspect of the development of the immune system and mediating an immune response. There is extensive and continual redistribution of cells to different anatomic sites throughout the body. These trafficking patterns control immune function, tissue regeneration, and host responses to insult. The ability to monitor the fate and function of cells, therefore, is imperative to both understanding the role of specific cells in disease processes and to devising rational therapeutic strategies. Determining the fate of immune cells and understanding the functional changes associated with migration and proliferation require effective means of obtaining in vivo measurements in the context of intact organ systems. A variety of imaging methods are available to provide structural information, such as X-ray CT and MRI, but only recently new tools have been developed that reveal cellular and molecular changes as they occur within living animals. We have pioneered one of these techniques that is based on the observations that light passes through mammalian tissues, and that luciferases can serve as internal biological sources of light in the living body. This method, called in vivo bioluminescence imaging, is a rapid and noninvasive functional imaging method that employs light-emitting reporters and external photon detection to follow biological processes in living animals in real time. This imaging strategy enables the studies of trafficking patterns for a variety of cell types in live animal models of human biology and disease. Using this approach we have elucidated the spatiotemporal trafficking patterns of lymphocytes within the body. In models of autoimmune disease we have used the migration of "pathogenic" immune cells to diseased tissues as a means to locally deliver and express therapeutic proteins. Similarly, we have determined the tempo of NK-T cell migration to neoplastic lesions and measured their life span in vivo. Using bioluminescence imaging individual groups of animals can be followed over time significantly reducing the number of animals per experiment, and improving the statistical significance of a study since changes in a given population can be studied over time. Such rapid assays that reveal cell fates in vivo will increase our basic understanding of the molecular signals that control these migratory pathways and will substantially speed up the development and evaluation of therapies. J. Cell. Biochem. Suppl. 39: 239,248, 2002. © 2002 Wiley-Liss, Inc. [source]

    A perception-driven autonomous urban vehicle

    John Leonard
    This paper describes the architecture and implementation of an autonomous passenger vehicle designed to navigate using locally perceived information in preference to potentially inaccurate or incomplete map data. The vehicle architecture was designed to handle the original DARPA Urban Challenge requirements of perceiving and navigating a road network with segments defined by sparse waypoints. The vehicle implementation includes many heterogeneous sensors with significant communications and computation bandwidth to capture and process high-resolution, high-rate sensor data. The output of the comprehensive environmental sensing subsystem is fed into a kinodynamic motion planning algorithm to generate all vehicle motion. The requirements of driving in lanes, three-point turns, parking, and maneuvering through obstacle fields are all generated with a unified planner. A key aspect of the planner is its use of closed-loop simulation in a rapidly exploring randomized trees algorithm, which can randomly explore the space while efficiently generating smooth trajectories in a dynamic and uncertain environment. The overall system was realized through the creation of a powerful new suite of software tools for message passing, logging, and visualization. These innovations provide a strong platform for future research in autonomous driving in global positioning system,denied and highly dynamic environments with poor a priori information. © 2008 Wiley Periodicals, Inc. [source]

    Comparison of micelles formed by amphiphilic star block copolymers prepared in the presence of a nonmetallic monomer activator

    Hoon Hyun
    Abstract In this article, we describe the synthesis of PEG- b -polyester star block copolymers via ring-opening polymerization (ROP) of ester monomers initiated at the hydroxyl end group of the core poly(ethylene glycol) (PEG) using HCl Et2O as a monomer activator. The ROP of ,-caprolactone (CL), trimethylene carbonate (TMC), or 1,4-dioxan-2-one (DO) was performed to synthesize PEG- b -polyester star block copolymers with one, two, four, and eight arms. The PEG- b -polyester star block copolymers were obtained in quantitative yield, had molecular weights close to the theoretical values calculated from the molar ratio of ester monomers to PEG, and exhibited monomodal GPC curves. The crystallinity of the PEG- b -polyester star block copolymers was determined by differential scanning calorimetry and X-ray diffraction. Copolymers with a higher arm number had a higher tendency toward crystallization. The crystallinity of the PEG- b -polyester star block copolymers also depended on the nature of the polyester block. The CMCs of the PEG- b -PCL star block copolymers, determined from fluorescence measurements, increased with increasing arm number. The CMCs of the four-arm star block copolymers with different polyester segments increased in the order 4a-PEG- b -PCL < 4a-PEG- b -PDO < 4a-PEG- b -PLGA < 4a-PEG- b -PTMC, suggesting a relationship between CMC and star block copolymer crystallinity. The partition equilibrium constant, Kv, which is an indicator of the hydrophobicity of the micelles of the PEG-polyester star block copolymers in aqueous media, increased with decreasing arm number and increasing crystallinity. A key aspect of the present work is that we successfully prepared PEG- b -polyester star block copolymers by a metal-free method. Thus, unlike copolymers synthesized by ROP using a metal as the monomer activator, our copolymers do not contain traces of metals and hence are more suitable for biomedical applications. Moreover, we confirmed that the PEG- b -polyester star block copolymers form micelles and hence may be potential hydrophobic drug delivery vehicles. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 2084,2096, 2008 [source]

    The King County (Washington) Systems Integration Initiative: A First Look at the Kent District Dual System Youth Pilot Program

    Gene Siegel
    ABSTRACT King County is one of five counties in Washington State participating in the John D. and Catherine T. MacArthur Foundation's Models for Change juvenile justice reform initiative. One key aspect of King County's Models for Change participation involves ongoing "systems integration" work intended to improve how youth who have cross-over involvement in multiple systems,e.g., juvenile justice, child welfare, education, mental health, and/or others,are handled. These cross-over cases often present a range of challenges to juvenile courts including substantial risk factors that increase their likelihood of continuing system involvement. This article provides a first look at an emerging pilot project in King County that is intended to improve how cross-over cases are handled by child welfare and juvenile probation with the longer term goal of improving outcomes for these difficult cases. [source]

    Kunyenga, "Real Sex," and Survival: Assessing the Risk of HIV Infection among Urban Street Boys in Tanzania

    Chris Lockhart
    This article examines possible avenues of HIV infection among urban street boys in Tanzania. In doing so, it questions the ways that AIDS researchers have defined and approached the phenomenon of "survival sex" in East and Central Africa. The article specifically examines the boys' sexual networks, sexual practices, and attitudes regarding their own sexual behavior, including their perceived risk of HIV/AIDS infection. Seventy-five street boys aged eight to 20 from the city ofMwanza were interviewed. Results suggest that almost all street boys are involved in a sexual network in which homosexual and heterosexual behavior occurs. Homosexual practices are rooted in a complex set of behaviors and ideologies known as kunyenga, which is a situated aspect of life on the streets and helps maintain the boys' strong dependence on one another. A key aspect of the boys' sexual careers involves a decrease in kunyenga activity as they approach the age of 18 and an increase in heterosexual encounters after the age of 11. There appears to be a critical period between these ages in which heterosexual and kunyenga activities overlap. It is suggested that boys between these ages represent a potential bridge for HIV/AIDS infection between the general population and the relatively enclosed sexual network of street boys. [Tanzania, street children, HIV/AIDS, sexual behavior] [source]

    Ex vivo assessment of mouse cervical remodeling through pregnancy via 23Na MRS

    NMR IN BIOMEDICINE, Issue 8 2010
    Xiang Xu
    Abstract Preterm birth occurs in 12.5% of births in the United States and can lead to risk of infant death or to lifelong serious health complications. A greater understanding by which the two main processes, uterine contraction and cervical remodeling are regulated is required to reduce rates of preterm birth. The cervix must undergo extensive remodeling through pregnancy in preparation for parturition, the process of labor and delivery of young. One key aspect of this dynamic process is a change in the composition and abundance of glycosaminoglycans (GAGs) and proteoglycans within the extracellular matrix, which influences the loss of tensile strength or stiffness of the cervix during labor. 23Na NMR spectroscopy has previously been validated as a method to quantify GAGs in tissues. In the current study, the Na+ concentration was measured at several time points through pregnancy in mouse cervices using 23Na NMR spectroscopy. The Na+ concentration increased progressively during pregnancy and peaked one day before birth followed by a rapid decline after birth. The same trend was seen in GAGs as measured by a biochemical assay using independent cervix samples over the course of pregnancy. We suggest that monitoring the Na+ concentration via 23Na NMR spectroscopy can serve as an informative physiological marker in evaluating the stages of cervical remodeling ex vivo and warrants further investigation to determine its utility as a diagnostic tool for the identification of women at risk for impending preterm birth. Copyright © 2010 John Wiley & Sons, Ltd. [source]

    How far are the left-behind left behind?

    A preliminary study in rural China
    Abstract While the linkage between migration and development has attracted much academic and policy attention, a key aspect of the linkage, namely those left behind in the community of origin, remains under-researched. As one of the first academic attempts to provide a systematic overview of this group in China, this paper describes the basic problems faced by it, discusses the institutional causes of the problems, and explores long-term and short-term solutions. The paper first establishes the fact that, while it seems that individuals decide who migrates and who stays back, there are fundamental institutional constraints on such decisions. The paper then shows that the three main left-behind groups, namely wives, the elderly and children, encounter various problems, but in general their situation is not much worse than that of those living with all family members. Their problems cannot just be attributed to being left-behind individuals; instead, the fundamental cause is that many rural communities as a whole have been left behind economically and socially. Although migration exacerbates the hardship, preventing migration is certainly not a solution. The paper instead calls for measures to redress the urban,rural divide and to improve the provision of public goods in rural communities. Copyright © 2006 John Wiley & Sons, Ltd. [source]

    An anisotropic viscoelastic model for collagenous soft tissues at large strains , Computational aspects

    Alexander E. Ehret
    This paper focusses on computational aspects related to a recently proposed anisotropic viscoelastic model for soft biological tissues at large strains [1]. A key aspect of this model is the generalisation of micromechanically motivated one-dimensional constitutive equations to three dimensions by numerical integration over the unit sphere. A strong effect of this procedure on the accuracy and in particular on the material symmetry of the model is observed. Finally a finite element example of an artery subject to normotensive blood pressure is presented. (© 2009 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

    Developing a performance measurement framework to enhance the impact orientation of the Food Research Institute, Ghana

    R & D MANAGEMENT, Issue 2 2006
    Robert M. Yawson
    Research institutions in Ghana are facing various challenges. It is the contention that viable research and development institutions are needed for achieving sustainable change in areas of national importance. A key aspect of institutional viability is strong performance management. This implies clear and workable approaches to performance measurement. This paper looks at the initial experiences in a collaborative effort to develop a performance measurement framework for the Food Research Institute (FRI) and the application of the Balanced Score Card (BSC) at institutional level. The process of diagnosing and analysing institutional monitoring and evaluation capacity and systems is described using a mix of diagnostic tools. Stages in applying the BSC approach are documented and the added value of the scorecard perspectives in highlighting focal areas for performance measurement and management within FRI. These are placed in the context of ongoing changes in the external environment posing both threats and opportunities. Changes implied by the introduction of the concept are discussed in the context of current constraints and the way forward is mapped out in terms of enhancing FRIs' impact orientation through the application of improved performance measurement and management. [source]

    Economic Insecurity and the Globalization of Production

    Kenneth Scheve
    A central question in the international and comparative political economy literatures on globalization is whether economic integration increases worker insecurity in advanced economies. Previous research has focused on the role of international trade and has failed to produce convincing evidence that such a link exists. In this article, we argue that globalization increases worker insecurity, but that foreign direct investment (FDI) by multinational enterprises (MNEs) is the key aspect of integration generating risk. FDI by MNEs increases firms' elasticity of demand for labor. More-elastic labor demands, in turn, raise the volatility of wages and employment, all of which tends to make workers feel less secure. We present new empirical evidence, based on the analysis of panel data from Great Britain collected from 1991 to 1999, that FDI activity in the industries in which individuals work is positively correlated with individual perceptions of economic insecurity. This correlation holds in analyses accounting for individual-specific effects and a wide variety of control variables. [source]