Poses Problems (pose + problem)

Distribution by Scientific Domains

Selected Abstracts

Spherically actuated platform manipulator

Robert L. Williams II
This article presents the inverse and forward pose and rate kinematics solutions for a novel 6-DOF platform manipulator, actuated by two base-mounted spherical actuators. The moving platform is connected to the fixed base by two identical spherical-prismatic-universal serial chain legs. The S -joint is active, and the remaining two joints in each chain are passive. An analytical solution is presented for the inverse pose problems, a semi-analytical solution is presented for the rate problems, and the numerical Newton,Raphson technique is employed to solve the forward pose problem. Unfortunately, the passive joint variables cannot be ignored in the kinematics solutions as they can for the Gough,Stewart platform. Examples are presented and hardware has been built, using two Rosheim Omni-Wrists on loan from NASA as the spherical actuators. © 2001 John Wiley & Sons, Inc. [source]

Attributed disability: a spot of local difficulty

George Peat PhD MCSP
Abstract There has been an exponential growth of publications relating to the development and application of health measurement instruments. Condition-specific measures have formed a large part of this trend. This article questions the rationale behind the concept of condition-specific disability, a common domain in such measures, taking musculoskeletal medicine as an example. It argues that physical functions are seldom unique to a specific condition and that measurement specificity therefore relies on attributing functional consequences to the health condition of interest. The presence of multi-morbidity (musculoskeletal and non-musculoskeletal), and the influence of personal and environmental factors, pose problems for attribution that have seldom been empirically investigated. Furthermore, attributing disability to a specific health condition of interest potentially limits insights into important interventions such as managing co-morbid interactions and targeting barriers in the physical, social, and attitudinal environment. Efforts to identify regionally relevant item content and to measure participation in daily life are a step in the right direction. Attribution is not needed for either. [source]

Spherically actuated platform manipulator

Robert L. Williams II
This article presents the inverse and forward pose and rate kinematics solutions for a novel 6-DOF platform manipulator, actuated by two base-mounted spherical actuators. The moving platform is connected to the fixed base by two identical spherical-prismatic-universal serial chain legs. The S -joint is active, and the remaining two joints in each chain are passive. An analytical solution is presented for the inverse pose problems, a semi-analytical solution is presented for the rate problems, and the numerical Newton,Raphson technique is employed to solve the forward pose problem. Unfortunately, the passive joint variables cannot be ignored in the kinematics solutions as they can for the Gough,Stewart platform. Examples are presented and hardware has been built, using two Rosheim Omni-Wrists on loan from NASA as the spherical actuators. © 2001 John Wiley & Sons, Inc. [source]

Accelerated nervous system development contributes to behavioral efficiency in the laboratory mouse: A behavioral review and theoretical proposal

Ian Q. Whishaw
Abstract The emergence of the laboratory mouse as a favored species for genetic research has posed a number of problems for scientists interested in the reflection of genetic influences in mouse behavior. It is commonly thought that rat behavior, which has been studied more extensively than mouse behavior, could be easily generalized to mice. In this article, a number of categories of behavior displayed by the mouse (motor, spatial, defensive, social) are reviewed and contrasted with the same categories of behavior displayed by the rat. The comparison suggests that mouse behavior is simpler and more dependent upon elementary actions than the behavior of the rat. We suggest that the behavioral simplification in the mouse adapts it for a different ecological niche than that occupied by the rat. We propose that this simplification may be mediated by accelerated brain maturation during development. We further propose that this developmental acceleration in the mouse renders it less dependent upon complex social behavior and plastic nervous system changes associated with learning than the rat. This difference poses problems for the development of relevant methods of behavioral analysis and interpretation. Since the mouse's biological adaptations will be reflected in laboratory behavior, suggestions are made for behavioral approaches to the study and interpretation of mouse behavior. © 2001 John Wiley & Sons, Inc. Dev Psychobiol 39: 151,170, 2001 [source]

A comparison of the relative contributions of temporal and spatial variation in the density of drifting invertebrates in a Dorset (U.K.) chalk stream

Summary 1. Invertebrate drift is commonly investigated in streams, with the majority of studies focussed on temporal (typically diel) variation. In comparison, few studies have investigated spatial variation in drift and there is little consensus among them. We tested the hypothesis that spatial variation in invertebrate drift is as important as temporal variation. 2. The density of drifting invertebrates in a chalk stream was sampled using an array of nets arranged to determine vertical, lateral and longitudinal variation. Samples were collected at dawn, during the day, at dusk and by night, on four separate monthly occasions. Insecta and Crustacea were analysed separately to identify the effect of differing life history strategies. The density of drifting debris was also recorded, to act as a null model. 3. Time of day and vertical position together explained the majority of the variance in invertebrate drift (79% for Insecta and 97% for Crustacea), with drift densities higher at dusk and night, and nearer the stream bed. Independently, time of day (38%, Insecta; 52%, Crustacea) and vertical position (41%, Insecta; 45%, Crustacea) explained a similar amount of the observed variance. Month explained some of the variance in insect drift (9%) but none for Crustacea. 4. Variation in the density of drifting debris showed little in common with invertebrate drift. There was little variation associated with time of day and only 27% of the observed variation in debris could be explained by the factors investigated here, with month explaining the largest proportion (20%). We suggest the difference in drifting debris and invertebrates provides further evidence for a strong behavioural component in invertebrate drift. 5. Spatial variation in invertebrate drift can be of the same order of magnitude as the much-described diel temporal variation. The extent of this spatial variation poses problems when attempting to quantify invertebrate drift and we recommend that spatial replication should be incorporated into drift studies. [source]

Benzodiazepines prescription in Dakar: a study about prescribing habits and knowledge in general practitioners, neurologists and psychiatrists

Amadou Moctar Dièye
Abstract Benzodiazepines are relatively well-tolerated medicines but can induce serious problems of addiction and that is why their use is regulated. However, in developing countries like Senegal, these products are used without clear indications on their prescription, their dispensation or their use. This work focuses on the prescription of these medicines with a view to make recommendations for their rational use. Benzodiazepine prescription was studied with psychiatrists or neurologists and generalists in 2003. Specialist doctors work in two Dakar university hospitals and generalists in the 11 health centres in Dakar. We did a survey by direct interview with 29 of 35 specialists and 23 of 25 generalists. All doctors were interviewed in their office. The questionnaire focused on benzodiazepine indications, their pharmacological properties, benzodiazepines prescribed in first intention against a given disease and the level of training in benzodiazepines by doctors. Comparisons between specialists and generalists were made by chi-square test. Benzodiazepines were essentially used for anxiety, insomnia and epilepsy. With these diseases, the most benzodiazepines prescribed are prazepam against anxiety and insomnia and diazepam against epilepsy. About 10% of doctors do not know that there is a limitation for the period of benzodiazepine use. The principal reasons of drugs choice are knowledge of the drugs, habit and low side effects of drugs. All generalists (100%) said that their training on benzodiazepines is poor vs. 62.1% of specialists, and doctors suggest seminars, journals adhesions and conferences to complete their training in this field. There are not many differences between specialists and generalists except the fact that specialists prefer prazepam in first intention in the insomnia treatment where generalists choose bromazepam. In addition, our survey showed that specialists' training in benzodiazepines is better than that of generalists. Overall, benzodiazepine prescription poses problems particularly in training, and national authorities must take urgent measures for rational use of these drugs. [source]

Computation of the J -integral for large strains

Ágnes Horváth
Abstract The phenomenon of failure by catastrophic crack propagation in structural materials poses problems of design and analysis in many fields of engineering. Cracks are present to some degree in all structures. They may exist as basic defects in the constituent materials or they may be induced in construction or during service life. Using the finite element method, a lot of papers deal with the calculation of stress intensity factors for two- and three-dimensional geometries containing cracks of different shapes under various loadings to elastic bodies. In order to increase the accuracy of the results, special elements have been used. They are described together with methods for calculating the stress intensity factors from the computed results. At the vicinity of a crack tip, the strains are not always small, but they may also be large. In this case, the J -integral can also be applied to characterize the cracks in elastic or elastic,plastic bodies. This paper describes the computation of the two-dimensional J -integral for large strains to elastic and elastic,plastic bodies and represents some numerical examples. Copyright © 2007 John Wiley & Sons, Ltd. [source]

Sexual development and reproductive seasonality of hogfish (Labridae: Lachnolaimus maximus), an hermaphroditic reef fish

R. S. McBride
The seasonality, size, age, colour phases and sexual dimorphism of 13 reproductive classes of hogfish Lachnolaimus maximus are described. Analysis of histological sections of gonads (n = 1662) confirmed earlier conclusions that L. maximus is a monandric, protogynous hermaphrodite. Sex change was initiated at the end of the spawning season and over a broad range of sizes and ages. It occurred after a functional female phase (postmaturation) and proceeded more slowly (months) than previously believed. Eventually all individuals changed sex to a terminal male phase. Females were batch spawners, spawning as often as every day during winter and spring. There was no evidence of precocious sperm crypts in active females, sperm competition or other alternative male sexual strategies. Mating has been reported elsewhere to be haremic. The sexual development of L. maximus appears to be adaptive in terms of Ghiselin's size-advantage model, which links monandric protogyny and polygyny. The slow rate of sex change, however, poses problems when fishing pressure is high because harvest of a single male has the potential to reduce the reproductive output of an entire harem. [source]

Particle Rearrangement and Pore Space Coarsening During Solid-State Sintering

Hans Eckart Exner
Coarsening of porosity during sintering has been observed in powder compacts of metallic, ceramic, and amorphous materials. Monitoring and modelling of the growth of individual (closed) pores in the late sintering stages are well established. Porosity is interconnected up to very high densities. Coarsening of the continuous pore space takes place during the initial and intermediate sintering stages. This coarsening is caused by localized transport of atoms or molecules (diffusion or viscous flow) as well as by bulk particle movement (rearrangement). Its quantitative exploration poses problems both experimentally and theoretically. Ways to characterize the geometry of the interconnected pore space and of closed pores are discussed with emphasis on stereological parameters. Recent and classical approaches, experimental findings with 2D model arrangements (as the formation and opening up of particle contacts, pore coarsening, and particle rearrangement) and some advances of computer simulations are discussed together with open questions. [source]

A hybrid approach to Web forum interactional coherence analysis

Tianjun Fu
Despite the rapid growth of text-based computer-mediated communication (CMC), its limitations have rendered the media highly incoherent. This poses problems for content analysis of online discourse archives. Interactional coherence analysis (ICA) attempts to accurately identify and construct CMC interaction networks. In this study, we propose the Hybrid Interactional Coherence (HIC) algorithm for identification of web forum interaction. HIC utilizes a bevy of system and linguistic features, including message header information, quotations, direct address, and lexical relations. Furthermore, several similarity-based methods including a Lexical Match Algorithm (LMA) and a sliding window method are utilized to account for interactional idiosyncrasies. Experiments results on two web forums revealed that the proposed HIC algorithm significantly outperformed comparison techniques in terms of precision, recall, and F-measure at both the forum and thread levels. Additionally, an example was used to illustrate how the improved ICA results can facilitate enhanced social network and role analysis capabilities. [source]

Following America into the second industrial revolution: new rules of competition and Ontario's farm machinery industry, 1850,1930

Despite the hiatus in farm expansion from 1880 to 1900, Canadian-owned Massey-Harris became a competitive multinational corporation as American branch plants arrived in Ontario. This equivocal performance in Canada's agricultural implements industry poses problems for explanations of Canada's branch plant economy. Most commentators blame an ill-conceived National Policy for promoting and protecting inefficient industry and frustrating industrial development. In reviewing their explanations, I use systematic comparisons among plants as well as between the Ontario, New York, Ohio, and Illinois industries. I argue that Canada's National Policy was an effective industrial policy that promoted competitive implement manufacture under the constraints of Victorian era technology. Problems emerged in the 1880s, however, as Chicago firms developed mass production in harvesting machinery, and these became entrenched as gasoline tractor development swept the industry after 1900. Ontario firms struggled, but they outperformed competitors in New York and Ohio, who had been industry leaders in] 880. Canada's branch plant economy in the farm machinery industry was made in Chicago and by mechanical engineers, not in Ottawa and by politicians. En dépit de l'hiatus dans l'expansion du pare agricole entre 1880 et 1900, la société canadienne Massey-Harris est devenue une grande société multinational compétitive lorsque des usines-succursales américaines ont fait leur arrivée en l'Ontario. Cette baisse de performance de I'Industrie canadienne de fabrication d'outils et d'engins agricoles pose des problèmes sur le plan de l'explication de l'économie des usines-succursales canadiennes. Pour la plupart des analystes, cette situation serait due à une politique nationals mal-conçue. Celle-ci aurait favorisé et protégé une Industrie inefficace, et ainsi frustré le développement industriel. En passant en revue ces analyses, je procède à une série de comparisons systématiques, d'une part des usines entre elles et, d'autre part, entre les industries de New York, de l'Ohio et de l'lllinois. J'avance que la Politique nationale canadienne etait une politique industrielle efficace qui a su promouvoir une Industrie de fabrication d'outils et d'engins agricoles compétitive dans le cadre de la technologie de l'époque victorienne et de ses contraintes. Des problèmes, qui ont fait leur apparition au cours des années 1880, suite à l'adoption par les sociétés de Chicago de la production de masse des moissonneuses, ont perduré suite à l'arrivée en masse des tracteurs à essence après 1900. Ce fut un moment très difficile pour les sociétés de l'Ontario mais elles réussirent à battre leurs concurrents de New York et de l'Ohio qui étaient leaders de l'industrie en 1880. Dans l'industrie des engins agricoles, le sort de l'économie des usines-succursales était décidéà Chicago, par des ingénieurs en mécanique agricole, non à Ottawa, par des hommes politiques. [source]

What's ,Social' about ,Social Capital'?

John Michael Roberts
Debates around the concept of social capital are often also debates about the level at which social capital can be abstracted for analytical use. Yet while many theorists and commentators involved in these debates implicitly discuss the issue of abstraction it is rarely done explicitly. In this article I attempt to overcome this missing link in the social capital literature by theoretically examining the ,social' in ,social capital' through interconnected levels of abstraction. In particular, and at a high level of abstraction, I argue that social capital is underpinned by a contradictory relationship associated with what I term as ,isolated reciprocity'. At lower levels of abstraction I show how isolated reciprocity poses problems for the establishment of ,good' social capital in the UK. [source]

The evaluation of retractions in sexual abuse cases

Bryan Tully
Abstract In some cases of alleged sexual abuse, the child or adult retracts allegations made. This poses problems for both civil and criminal legal proceedings. It is argued that the collection and examination of retraction statements often does not receive the same careful attention as is the case with the investigation of the original allegations. Logically, depending on whether the original complaints were true or false or a mixture, so the meaning of a retraction may vary. Where retractions are examined and evaluated with care they may be shown to add to the confidence of the final conclusion rather than simply throwing doubt on that. A systematic approach is described, followed by three cases where such application assisted and paradoxically added to the probative value of earlier statements. Copyright © 2002 John Wiley & Sons, Ltd. [source]

Incontinence following sphincter division for treatment of anal fistula

COLORECTAL DISEASE, Issue 7Online 2010
S. Bokhari
Abstract Objective, Management of anal fistula poses problems because of competing goals of cure and maintenance of continence. There is increasing recognition of significant rates of incontinence after sphincter-dividing anal surgery. We aimed to determine cure and continence status in a cohort of anal fistula patients managed by both sphincter-dividing and conserving approaches. Method, Data on fistula, healing and continence status were gathered by patient questionnaire (Cleveland Clinic incontinence questionnaire), telephone interview and chart review. Fistulae were defined as simple (low risk of incontinence) or complex (high risk). Surgery was defined as sphincter conservation and sphincter division. Incontinence was graded by traditional severity scale (minor/major). Fistula healing was defined as absence of acute or chronic sepsis symptoms from surgery to date of last follow-up. Results, One hundred and twenty-eight patients were evaluated (out of whom 71% were male subjects, age range 17,82, median age 45 years). Fifty-two percent of the fistulae were complex and 48% were simple, of which 51% and 85% underwent sphincter division respectively. Healing rates were higher for sphincter division than conservation (87%vs 73%, P = 0.06). Complex fistulae undergoing sphincter division led to a higher rate of major incontinence (13%) than sphincter conservation (0%) (P = 0.03). For simple fistulae treated by sphincter division, major (5%) and minor incontinence (11%) was not inconsiderable. Conclusion, Though cure rates are excellent, incontinence rates remain unacceptably high following sphincter division for complex fistulae and are not insignificant even for simple fistulae. More sphincter conservation should be undertaken. [source]