4,187 research outputs found

    Community Group-Based Models of Medication Delivery: Applicability to Cardiovascular Diseases.

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    The rising global burden of chronic non-communicable diseases (NCDs) has put a strain on healthcare systems globally, especially in low- and middle-income countries, which have seen disproportionate mortality rates due to non-communicable diseases. These deaths are in part due to challenges with medication adherence, which are compounded by lack of access to medication and weak community support systems. This paper aims to propose a potential solution using models of service delivery in HIV/AIDS, given the many similarities between NCD and HIV/AIDS. Models that have been particularly effective in HIV/AIDS are the community-based peer-support medication delivery groups: medication adherence clubs and community antiretroviral therapy (ART) groups. The positive outcomes from these models, including improved medication adherence and patient satisfaction, provide evidence for their potential success when applied to non-communicable diseases, particularly hypertension and cardiovascular disease

    Molecular Dynamics Simulation of Polymer-Metal Bonds

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    Molecular simulation is becoming a very powerful tool for studying dynamic phenomena in materials. The simulation yields information about interaction at length and time scales unattainable by experimental measurements and unpredictable by continuum theories. This is especially meaningful when referring to bonding between a polymer and a metal substrate. A very important characteristic of polymers is that their physical properties do not rely on the detailed chemical structure of the molecular chains but only on their flexibility, and accordingly they will be able to adopt different conformations. In this paper, a molecular simulation of the bonding between vinyl ester polymer and steel is presented. Four different polymers with increasing chain lengths have been studied. Atomic co-ordinates are adjusted in order to reduce the molecular energy. Conformational changes in the macromolecules have been followed to obtain the polymer pair correlation function. Radius of gyration and end-to-end distance distributions of the individual chains have been used as a quantitative measurement of their flexibility. There exists a correlation between flexibility of the molecular chains and the energy of adhesion between the polymer and the metal substrate. Close contacts between the two materials are established at certain points but every atom up to a certain distance from the interface contributes to the total value of the adhesion energy of the system

    Thermodynamically consistent description of the hydrodynamics of free surfaces covered by insoluble surfactants of high concentration

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    In this paper we propose several models that describe the dynamics of liquid films which are covered by a high concentration layer of insoluble surfactant. First, we briefly review the 'classical' hydrodynamic form of the coupled evolution equations for the film height and surfactant concentration that are well established for small concentrations. Then we re-formulate the basic model as a gradient dynamics based on an underlying free energy functional that accounts for wettability and capillarity. Based on this re-formulation in the framework of nonequilibrium thermodynamics, we propose extensions of the basic hydrodynamic model that account for (i) nonlinear equations of state, (ii) surfactant-dependent wettability, (iii) surfactant phase transitions, and (iv) substrate-mediated condensation. In passing, we discuss important differences to most of the models found in the literature.Comment: 31 pages, 2 figure

    About Those New Oats - Burnett and Newton

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    These two new oat varieties will be available for planting in 1958. You can see them growing this year at Iowa State College or in the fields of certified seed producers. Here are the details on what you can expect

    Elucidating the Influence of the Activation Energy on Reaction Rates by Simulations Based on a Simple Particle Model

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    An application for visualizing the dynamic properties of an equimolar binary mixture of isotropic reactive particles is presented. By introducing a user selectable choice for the activation energy, the application is useful to demonstrate qualitatively that the reaction rate depends on the above choice and on temperature. The application is based on a 2D realistic dynamic model where atoms move because of their thermal energies and the trajectories are determined by solving numerically Newton’s laws according to a Molecular Dynamics (MD) scheme. Collisions are monitored as time progresses, and every time the collision energy is larger than the selected activation energy, a reactive event occurs. By examining the time evolution of the configurations, it is possible to observe that the number of reactive collisions is always smaller than the total number of collisions. However, the number of reactive events increases on raising the temperature and/or by decreasing the activation energy. The above observations, as well as more quantitative analyses of the simulation data, are useful in elucidating the connections existing among particle kinetic energy, temperature, and activation energy of the reaction. The application can be used at different levels of detail and in different instruction levels. Qualitative visual observations of the progress of the reaction are suitable at all levels of instruction. Systematic investigations on the effect of changes of temperature and activation energy, suitable for senior high school and college courses and useful to gain insight into kinetic models and Arrhenius’ law, are also reported

    Hybrid Performance of Sorghum Parental Lines Developed by Mass Selection and S1 Yield Testing

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    Experiments were conducted co obtain information on the effects of two methods of developing parental lines from a random-mating population of sorghum (Sorghum bicolor L. Moench) on hybrid performance. Gridded mass selection for threshed panicle weight was used in developing IAP1R(M)C3: and a sister population, IAP4R(S1)C3, was advanced each cycle on the basis of grain yield of S1 families in replicated yield trials. Hybrids with male parents developed by mass selection did not differ significantly for grain yield and panicles/plant from those with parents chosen on the basis of S1 yield tests. The S1-selection hybrids were significantly (P ≤0.01 or P ≤0.05) shorter and later to bloom, had smaller seed and more seeds/panicle, but the differences usually were small and of little practical consequence. Estimates of generic variance, heritability, and expected gain from selection among hybrids developed with mass or S1 selected male parents were similar for grain yield and most other characters. Collectively, the results of our experiments indicated that developing sorghum parental lines by using mass selection for panicle weight or replicated S1 yield tests should be equally effective

    Kinetic Energy Density Study of Some Representative Semilocal Kinetic Energy Functionals

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    There is a number of explicit kinetic energy density functionals for non-interacting electron systems that are obtained in terms of the electron density and its derivatives. These semilocal functionals have been widely used in the literature. In this work we present a comparative study of the kinetic energy density of these semilocal functionals, stressing the importance of the local behavior to assess the quality of the functionals. We propose a quality factor that measures the local differences between the usual orbital-based kinetic energy density distributions and the approximated ones, allowing to ensure if the good results obtained for the total kinetic energies with these semilocal functionals are due to their correct local performance or to error cancellations. We have also included contributions coming from the laplacian of the electron density to work with an infinite set of kinetic energy densities. For all the functionals but one we have found that their success in the evaluation of the total kinetic energy are due to global error cancellations, whereas the local behavior of their kinetic energy density becomes worse than that corresponding to the Thomas-Fermi functional.Comment: 12 pages, 3 figure
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