Problems in the coupling of eye and hand in the sequential movements of children with developmental coordination disorder

Background: Shifting gaze and attention ahead of the hand is a natural component in the performance of skilled manual actions. Very few studies have examined the precise co-ordination between the eye and hand in children with Developmental Coordination Disorder (DCD). Methods This study directly assessed the maturity of eye-hand co-ordination in children with DCD. A double-step pointing task was used to investigate the coupling of the eye and hand in 7-year-old children with and without DCD. Sequential targets were presented on a computer screen, and eye and hand movements were recorded simultaneously. Results There were no differences between typically developing (TD) and DCD groups when completing fast single-target tasks. There were very few differences in the completion of the first movement in the double-step tasks, but differences did occur during the second sequential movement. One factor appeared to be the propensity for the DCD children to delay their hand movement until some period after the eye had landed on the target. This resulted in a marked increase in eye-hand lead during the second movement, disrupting the close coupling and leading to a slower and less accurate hand movement among children with DCD. Conclusions In contrast to skilled adults, both groups of children preferred to foveate the target prior to initiating a hand movement if time allowed. The TD children, however, were more able to reduce this foveation period and shift towards a feedforward mode of control for hand movements. The children with DCD persevered with a look-then-move strategy, which led to an increase in error. For the group of DCD children in this study, there was no evidence of a problem in speed or accuracy of simple movements, but there was a difficulty in concatenating the sequential shifts of gaze and hand required for the completion of everyday tasks or typical assessment items.

The demand for a healthy diet: estimating the almost ideal demand system with infrequency of purchase

A Bayesian method of estimating multivariate sample selection models is introduced and applied to the estimation of a demand system for food in the UK to account for censoring arising from infrequency of purchase. We show how it is possible to impose identifying restrictions on the sample selection equations and that, unlike a maximum likelihood framework, the imposition of adding up at both latent and observed levels is straightforward. Our results emphasise the role played by low incomes and socio-economic circumstances in leading to poor diets and also indicate that the presence of children in a household has a negative impact on dietary quality.

Speech motor control in fluent and dysfluent speech production of an individual with apraxia of speech and Broca���s aphasia

Apraxia of speech (AOS) is typically described as a motor-speech disorder with clinically well-defined symptoms, but without a clear understanding of the underlying problems in motor control. A number of studies have compared the speech of subjects with AOS to the fluent speech of controls, but only a few have included speech movement data and if so, this was primarily restricted to the study of single articulators. If AOS reflects a basic neuromotor dysfunction, this should somehow be evident in the production of both dysfluent and perceptually fluent speech. The current study compared motor control strategies for the production of perceptually fluent speech between a young woman with apraxia of speech (AOS) and Broca���s aphasia and a group of age-matched control speakers using concepts and tools from articulation-based theories. In addition, to examine the potential role of specific movement variables on gestural coordination, a second part of this study involved a comparison of fluent and dysfluent speech samples from the speaker with AOS. Movement data from the lips, jaw and tongue were acquired using the AG-100 EMMA system during the reiterated production of multisyllabic nonwords. The findings indicated that although in general kinematic parameters of fluent speech were similar in the subject with AOS and Broca���s aphasia to those of the age-matched controls, speech task-related differences were observed in upper lip movements and lip coordination. The comparison between fluent and dysfluent speech characteristics suggested that fluent speech was achieved through the use of specific motor control strategies, highlighting the potential association between the stability of coordinative patterns and movement range, as described in Coordination Dynamics theory.

History teachers��� thinking about the nature of their subject

This paper addresses how secondary history teachers view the nature and purposes of their subject and how they think these views impact on their practice. Data were collected through individual qualitative interviews with eleven UK history teachers at the start of their careers. Their views on the nature of history are broadly empiricist with postmodern perspectives having been less influential. Their rationales for the subject emphasise broader educational purposes. The case for further emphasis on subject understandings in teacher education is made through a consideration of the implications of a lack of emphasis of more postmodern perspectives on classroom practice.

Permanence of stability for a class of system of differential equations with two delays

The paper studies a class of a system of linear retarded differential difference equations with several parameters. It presents some sufficient conditions under which no stability changes for an equilibrium point occurs. Application of these results is given. (c) 2007 Elsevier Ltd. All rights reserved.

STABILITY ANALYSIS WITH APPLICATIONS OF A TWO-DIMENSIONAL DYNAMICAL SYSTEM ARISING FROM A STOCHASTIC MODEL FOR AN ASSET MARKET

We analyze the stability properties of equilibrium solutions and periodicity of orbits in a two-dimensional dynamical system whose orbits mimic the evolution of the price of an asset and the excess demand for that asset. The construction of the system is grounded upon a heterogeneous interacting agent model for a single risky asset market. An advantage of this construction procedure is that the resulting dynamical system becomes a macroscopic market model which mirrors the market quantities and qualities that would typically be taken into account solely at the microscopic level of modeling. The system`s parameters correspond to: (a) the proportion of speculators in a market; (b) the traders` speculative trend; (c) the degree of heterogeneity of idiosyncratic evaluations of the market agents with respect to the asset`s fundamental value; and (d) the strength of the feedback of the population excess demand on the asset price update increment. This correspondence allows us to employ our results in order to infer plausible causes for the emergence of price and demand fluctuations in a real asset market. The employment of dynamical systems for studying evolution of stochastic models of socio-economic phenomena is quite usual in the area of heterogeneous interacting agent models. However, in the vast majority of the cases present in the literature, these dynamical systems are one-dimensional. Our work is among the few in the area that construct and study analytically a two-dimensional dynamical system and apply it for explanation of socio-economic phenomena.

Energy Storage for a Grid-Connected PV-System: A Feasibility Study

The work presented in this thesis concerns the dimensioning of an Energy Storage System (ESS) which will be used as an energy buffer for a grid-connected PV plant. This ESS should help managing the PV plant to inject electricity into the grid according to the requirements of the grid System Operator. It is desired to obtain a final production not below 1300kWh/kWp with a maximum ESS budget of 0.9���/Wp. The PV plant will be sited in Martinique Island and connected to the main grid. This grid is a small one where the perturbations due clouds in the PV generation are not negligible anymore. A software simulation tool, incorporating a model for the PV-plant production, the ESS and the required injection pattern of electricity into the grid has been developed in MS Excel. This tool has been used to optimize the relevant parameters defining the ESS so that the feed-in of electricity into the grid can be controlled to fulfill the conditions given by the System Operator. The inputs used for this simulation tool are, besides the conditions given by the System Operator on the allowed injection pattern, the production data from a similar PV-plant in a close-by location, and variables for defining the ESS. The PV production data used is from a site with similar climate and weather conditions as for the site on the Martinique Island and hence gives information on the short term insolation variations as well as expected annual electricity production. The ESS capacity and the injected electric energy will be the main figures to compare while doing an economic study of the whole plant. Hence, the Net Present Value, Benefit to Cost method and Pay-back period studies are carried on as dependent of the ESS capacity. The conclusion of this work is that it is possible to obtain the requested injection pattern by using an ESS. The design of the ESS can be made within an acceptable budget. The capacity of ESS to link with the PV system depends on the priorities of the final output characteristics, and it also depends on which economic parameter that is chosen as a priority.

O Prob��sica e a forma����o de professores no P��lo de Parnamirim: pol��tica de forma����o profissional no Rio Grande do Norte?

This work studies the thematic of the politics of formation of teachers in the Program of Professional Qualification for Basic Education (PROB��SICA) developed in the City of Parnamirim, Rio Grande do Norte. It has as its main objective to identify and to analyze the contribution of this politics of initial formation for the professional formation of teachers. To install the work, we will use the procedures of bibliographical research, documentary analysis, comment, structuralized interview, questionnaire-script and virtual research. In the analysis of the data, we trace a general view on PROB��SICA while initial formation along with the continued formation, pedagogical research, collaborative research and the exercise of the teaching profession, identifying the possibilities and limits of the Program in the direction to reach the objective considered in this work. From the inquiry, we construct the institutional land scope of the program in question, also focusing, the organizational aspects of its functioning. We have to take care about the results, we evidence that PROB��SICA is making the possible to access of the teachers in the educational service to the University, what the main aspect that consists, trying to prove eminent weak points in its systematic due to give to the organizational structure of this educational politics that does not count with curricular, institutional and financial the necessary conditions for the success of the professional formation of the teachers. The research will try to understand that the operationalization of the politics of formation in Parnamirim will be belong with it the main idea of the Educational Reformation in years of 1990, articulated to the neoliberal interests, that the responsibility for the problems of the public system of education attributed to the teachers, and that are not answered completely through the purpose of the professional formation, and ti seems that it does not define one global national politics that deals with seriousness to the questions the initial formation, permanent formation, pedagogical research, , career and conditions of work for the teachers

Histopathological analysis of the reproductive system of male dogs experimentally infected with Toxoplasma gondii

O presente trabalho teve como objetivo descrever eventuais altera����es histopatol��gicas no sistema reprodutor (test��culo e epid��dimo) de c��es machos experimentalmente infectados com Toxoplasma gondii. Para tal, 10 animais sorologicamente negativos para T. gondii foram selecionados e distribu��dos em tr��s grupos experimentais: GI - tr��s c��es inoculados com 2,0 x 10(5) oocistos da cepa P, GII - tr��s c��es infectados com 1,0 x 10(6) taquizo��tos da cepa RH e GIII - quatro c��es mantidos como controle. Pesquisa de anticorpos (IFI) contra T. gondii foi realizada. A infec����o por T. gondii confirmou-se pela soroconvers��o de todos os machos infectados a partir do 7�� e do 14�� dia p��s-inocula����o (DPI) para c��es que receberam taquizo��tos e oocistos respectivamente. Decorridos 70DPI, realizou-se, em todos os c��es, orquiectomia, e amostras (test��culo e epid��dimo) foram coletadas e processadas histologicamente para leitura em microsc��pio ��ptico. As seguintes altera����es foram diagnosticadas: infiltrado inflamat��rio mononuclear leve e moderado em epid��dimo, edema celular moderado, degenera����o hidr��pica e fibrose intersticial moderada em t��bulos semin��feros. Os resultados histopatol��gicos do presente trabalho, aliados ao isolamento do T. gondii em fragmentos de test��culo e epid��dimo pela imunoistoqu��mica, juntamente com os resultados encontrados na literatura por outros autores em diferentes tecidos, permitem inferir que as altera����es encontradas nos c��es infectados com o respectivo protozo��rio s��o sugestivas de infec����o toxopl��smica.

Root system of Panicum maximum Jacq. cv. IPR-86 Mil(e)over-capnio fertilized with nitrogen and submitted to rotational stocking

The effect of nitrogen on the root system of the species Panicum maximum Jacq. cv. IPR-86 Mil (e) over cap nio, under grazing, was evaluated. The N rates were 0; 150; 300 and 450 kg/ha. year. The root density was evaluated during pregrazing at five years of successive N application, in three depths (0-10; 10-20 and 20-40 cm) and the root growth at 7, 14, 21, and 35 days after grazing. The grazing method adopted was rotational stocking. Root length and root mass densities in pre-and post-grazing presented maximum values at rates 204, 206, 192, and 197 kg/ha of N, respectively. The root growth (in root length density) increased, on average, until 29 days after grazing at rates 0, 150, and 300 kg/ha; at 450 kg/ha N rate, the increase was linear. Independently of N rates, around 60 and 25% of IPR-86 Mil (e) over cap nio cultivar root system was concentrated in 0-10 and 10-20 cm depth, respectively.

Electricity, hot water and cold water production from biomass. Energetic and economical analysis of the compact system of cogeneration run with woodgas from a small downdraft gasifier

Wood gasification technologies to convert the biomass into fuel gas stand out. on the other hand, producing electrical energy from stationary engine is widely spread, and its application in rural communities where the electrical network doesn't exist is very required. The recovery of exhaust gases (engine) is a possibility that makes the system attractive when compared with the same components used to obtain individual heat such as electric power. This paper presents an energetic alternative to adapt a fixed bed gasifier with a compact cogeneration system in order to cover electrical and thermal demands in a rural area and showing an energy solution for small social communities using renewable fuels. Therefore, an energetic and economical analysis from a cogeneration system producing electric energy, hot and cold water, using wooden gas as fuel from a small-sized gasifier was calculated. The energy balance that includes the energy efficiency (electric generation as well as hot and cold water system; performance coefficient and the heat exchanger, among other items), was calculated. Considering the annual interest rates and the amortization periods, the costs of production of electrical energy, hot and cold water were calculated, taking into account the investment, the operation and the maintenance cost of the equipments. Crown Copyright (C) 2010 Published by Elsevier Ltd. All rights reserved.