1,279 research outputs found

    Child disobedience and noncompliance: A review [IF: 3.4]

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    Child disobedience and noncompliance is a recurring problem frequently brought to the attention of pediatricians and others working with children and their parents. This article reviews empirical studies concerning childhood noncompliance. Definitions of noncompliance (also called disobedience) are presented, and observational studies that have measured noncompliance in the laboratory and at home are reviewed. Studies show considerable variability in the prevalence of noncompliance, but demonstrate that it is a frequent problem for parents. Longitudinal data from the Pittsburgh Youth Study are presented to more closely examine the onset and stability of noncompliance in childhood and adolescence. Evidence suggests that extreme childhood noncompliance is relatively stable over time, peaking slightly during early adolescence and decreasing during late adolescence. Studies indicate that for some children noncompliance predicts aggression and externalizing problems. Antecedents of noncompliance including parental discipline techniques and child characteristics are reviewed. Parent training programs designed to reduce noncompliance are described, and the effectiveness of such programs is examined

    Algorithm for Stabilizing a POD-Based Dynamical System

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    This algorithm provides a new way to improve the accuracy and asymptotic behavior of a low-dimensional system based on the proper orthogonal decomposition (POD). Given a data set representing the evolution of a system of partial differential equations (PDEs), such as the Navier-Stokes equations for incompressible flow, one may obtain a low-dimensional model in the form of ordinary differential equations (ODEs) that should model the dynamics of the flow. Temporal sampling of the direct numerical simulation of the PDEs produces a spatial time series. The POD extracts the temporal and spatial eigenfunctions of this data set. Truncated to retain only the most energetic modes followed by Galerkin projection of these modes onto the PDEs obtains a dynamical system of ordinary differential equations for the time-dependent behavior of the flow. In practice, the steps leading to this system of ODEs entail numerically computing first-order derivatives of the mean data field and the eigenfunctions, and the computation of many inner products. This is far from a perfect process, and often results in the lack of long-term stability of the system and incorrect asymptotic behavior of the model. This algorithm describes a new stabilization method that utilizes the temporal eigenfunctions to derive correction terms for the coefficients of the dynamical system to significantly reduce these errors

    Parameterizing Coefficients of a POD-Based Dynamical System

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    A method of parameterizing the coefficients of a dynamical system based of a proper orthogonal decomposition (POD) representing the flow dynamics of a viscous fluid has been introduced. (A brief description of POD is presented in the immediately preceding article.) The present parameterization method is intended to enable construction of the dynamical system to accurately represent the temporal evolution of the flow dynamics over a range of Reynolds numbers. The need for this or a similar method arises as follows: A procedure that includes direct numerical simulation followed by POD, followed by Galerkin projection to a dynamical system has been proven to enable representation of flow dynamics by a low-dimensional model at the Reynolds number of the simulation. However, a more difficult task is to obtain models that are valid over a range of Reynolds numbers. Extrapolation of low-dimensional models by use of straightforward Reynolds-number-based parameter continuation has proven to be inadequate for successful prediction of flows. A key part of the problem of constructing a dynamical system to accurately represent the temporal evolution of the flow dynamics over a range of Reynolds numbers is the problem of understanding and providing for the variation of the coefficients of the dynamical system with the Reynolds number. Prior methods do not enable capture of temporal dynamics over ranges of Reynolds numbers in low-dimensional models, and are not even satisfactory when large numbers of modes are used. The basic idea of the present method is to solve the problem through a suitable parameterization of the coefficients of the dynamical system. The parameterization computations involve utilization of the transfer of kinetic energy between modes as a function of Reynolds number. The thus-parameterized dynamical system accurately predicts the flow dynamics and is applicable to a range of flow problems in the dynamical regime around the Hopf bifurcation. Parameter-continuation software can be used on the parameterized dynamical system to derive a bifurcation diagram that accurately predicts the temporal flow behavior

    Flow Solver for Incompressible 2-D Drive Cavity

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    This software solves the Navier-Stokes equations for the incompressible driven cavity flow problem. The code uses second-order finite differencing on a staggered grid using the Chorin projection method. The resulting intermediate Poisson equation is efficiently solved using the fast Fourier transform. Time stepping is done using fourth-order Runge-Kutta for stability at high Reynolds numbers. Features include check-pointing, periodic field snapshots, ongoing reporting of kinetic energy and changes between time steps, time histories at selected points, and optional streakline generation

    Towards a direct transition energy measurement of the lowest nuclear excitation in 229Th

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    The isomeric first excited state of the isotope 229Th exhibits the lowest nuclear excitation energy in the whole landscape of known atomic nuclei. For a long time this energy was reported in the literature as 3.5(5) eV, however, a new experiment corrected this energy to 7.6(5) eV, corresponding to a UV transition wavelength of 163(11) nm. The expected isomeric lifetime is Ï„=\tau= 3-5 hours, leading to an extremely sharp relative linewidth of Delta E/E ~ 10^-20, 5-6 orders of magnitude smaller than typical atomic relative linewidths. For an adequately chosen electronic state the frequency of the nuclear ground-state transition will be independent from influences of external fields in the framework of the linear Zeeman and quadratic Stark effect, rendering 229mTh a candidate for a reference of an optical clock with very high accuracy. Moreover, in the literature speculations about a potentially enhanced sensitivity of the ground-state transition of 229m^{229m}Th for eventual time-dependent variations of fundamental constants (e.g. fine structure constant alpha) can be found. We report on our experimental activities that aim at a direct identification of the UV fluorescence of the ground-state transition energy of 229mTh. A further goal is to improve the accuracy of the ground-state transition energy as a prerequisite for a laser-based optical control of this nuclear excited state, allowing to build a bridge between atomic and nuclear physics and open new perspectives for metrological as well as fundamental studies

    Organic small molecule field-effect transistors with Cytop(TM) gate dielectric: eliminating gate bias stress effects

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    We report on organic field-effect transistors with unprecedented resistance against gate bias stress. The single crystal and thin-film transistors employ the organic gate dielectric Cytop(TM). This fluoropolymer is highly water repellent and shows a remarkable electrical breakdown strength. The single crystal transistors are consistently of very high electrical quality: near zero onset, very steep subthreshold swing (average: 1.3 nF V/(dec cm2)) and negligible current hysteresis. Furthermore, extended gate bias stress only leads to marginal changes in the transfer characteristics. It appears that there is no conceptual limitation for the stability of organic semiconductors in contrast to hydrogenated amorphous silicon.Comment: 4 pages, 3 figures, to be published in Appl. Phys. Let

    An Occupational Therapy-Based Education Program for Caregivers of Individuals with Cerebral Palsy: A Culturally Conscious Perspective

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    Introduction: Individuals with cerebral palsy (CP) are able to lead functional, productive, and fulfilling lives when provided the opportunity. In the country of Ghana, the prevalence of CP is estimated to be one out of every 300 births (Purple Field Productions [PFP], 2011), however, a lack of education about CP and other disabilities, limited access to healthcare services, and scarce resources hamper the Ghanaian people’s opportunities for habilitation (Reynolds, 2010; Tinney, Chiodo, Haig, & Wiredu, 2007). In addition, cultural beliefs and societal attitudes toward people with disabilities in Ghana pose a barrier for those individuals to fully participate in occupation. According to the World Federation of Occupational Therapy (WFOT), occupational therapists have a responsibility and an opportunity to address occupational injustices through the development of programs for underserved populations (WFOT, 2006). Occupational therapy (OT) is an established element in the treatment of impairments and symptoms associated with CP (Steultjens et al., 2004). Often OT intervention includes parent or caregiver education. Because of the lack of access to medical care and therapy services, as well as the stigma related with disability, much of the care of individuals with CP is up to family members or informal caregivers. These caregivers often do not have access to the training or resources they need (Tinney et al., 2007). Purpose: The purpose of this program is to enable caregivers in Ghana with the training and knowledge of the basic skills and assistive devices to more effectively care for individuals with CP while enabling those with CP to engage in occupations more independently. It is also intended to empower the caregivers to pass on the skills and knowledge to other caregivers in their communities. Methodology: A review of literature was conducted including use of professional journals, textbooks, and organizational websites. Topics investigated were Ghana; disability culture, provision of healthcare and resources, and CP in Ghana; OT interventions for individuals with CP; and adult education principles. In addition, data from a needs assessment was obtained to provide a personal perspective for content of the product and targeted audience. Three compatible Canadian occupational behavioral models guided the literature review and development of the product: Person-Environment-Occupation Model, Canadian Model of Occupational Performance and Engagement, and the Canadian Model of Client-Centered Enablement. Conclusion: Implementation of this program is intended to enable and empower caregivers in Ghana to carry out that role more effectively, in turn improving the occupational performance and engagement of individuals with CP. It is recommended to be used within the curriculum of the University of North Dakota OT Department’s international service learning course as pilot program. It is expected the participants of the course will learn the contents of the product, How to Help a Child with Cerebral Palsy, before distributing it to and using it as a guide in teaching caregivers in Ghana during the fieldwork portion of the course
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