300 research outputs found

    Effects of an aquagym training in postmepausal women

    Full text link
    Los cambios en la composición corporal de mujeres posmenopáusicas, principalmente, el aumento del tejido adiposo visceral y abdominal, son indicadores de enfermedades metabólicas y cardiovasculares. Veintiuna mujeres posmenopáusicas participaron en un programa de 16 semanas de clases de Aquagym. Las variables analizadas fueron la circunferencia de cintura (CCi), la circunferencia de cadera (CCa), el índice cintura-cadera (ICC), el diámetro sagital abdominal (DAS) y el tejido adiposo visceral (TAV). El tratamiento estadístico empleado fue una prueba t para comparar entre los grupos y el test de Goodman para analizar las alteraciones en la clasificación cualitativa del ICC. Se han obtenido reducciones significativas (p≤0,05) para todas las variables medidas después de la intervención de ejercicio. El programa de Aquagym fue capaz de reducir el tejido adiposo visceral y abdominal, además de disminuir el riego para el desarrollo de enfermedades de enfermedades metabólicas y cardiovasculares, constituyendo una estrategia eficaz para tratar la obesidad central.Changes in body composition in postmenopausal women and increased abdominal visceral adipose tissue are markers of metabolic and cardiovascular diseases. Twenty-one postmenopausal women participated in Aquagym's classes during 16 weeks. The analyzed variables included measures of waist circumference (WC), hip circumference (HC), waist-hip ratio (ICC), abdominal sagittal diameter (ASD) and intra-abdominal adipose tissue (IAAT). Statistical treatment was used as the paired t test for comparisons between the groups before and after Aquagym practice and Goodman`s test to analyze the changes in the qualitative classification of the ICC. Significant reductions (p≤0.05) have been found for all measured variables. Aquagym program was able to reduce the abdominal visceral adipose tissue, thus decreasing the risk of developing metabolic and cardiovascular diseases, constituting an effective strategy to deal with central obesity

    Bose-Einstein Condensation of Helium and Hydrogen inside Bundles of Carbon Nanotubes

    Full text link
    Helium atoms or hydrogen molecules are believed to be strongly bound within the interstitial channels (between three carbon nanotubes) within a bundle of many nanotubes. The effects on adsorption of a nonuniform distribution of tubes are evaluated. The energy of a single particle state is the sum of a discrete transverse energy Et (that depends on the radii of neighboring tubes) and a quasicontinuous energy Ez of relatively free motion parallel to the axis of the tubes. At low temperature, the particles occupy the lowest energy states, the focus of this study. The transverse energy attains a global minimum value (Et=Emin) for radii near Rmin=9.95 Ang. for H2 and 8.48 Ang.for He-4. The density of states N(E) near the lowest energy is found to vary linearly above this threshold value, i.e. N(E) is proportional to (E-Emin). As a result, there occurs a Bose-Einstein condensation of the molecules into the channel with the lowest transverse energy. The transition is characterized approximately as that of a four dimensional gas, neglecting the interactions between the adsorbed particles. The phenomenon is observable, in principle, from a singular heat capacity. The existence of this transition depends on the sample having a relatively broad distribution of radii values that include some near Rmin.Comment: 21 pages, 9 figure

    Diversity and neocolonialism in Big Data research: Avoiding extractivism while struggling with paternalism

    Get PDF
    The extractive logic of Big Data-driven technology and knowledge production has raised serious concerns. While most criticism initially focused on the impacts on Western societies, attention is now increasingly turning to the consequences for communities in the Global South. To date, debates have focused on private-sector activities. In this article, we start from the conviction that publicly funded knowledge and technology production must also be scrutinized for their potential neocolonial entanglements. To this end, we analyze the dynamics of collaboration in an European Union-funded research project that collects data for developing a social platform focused on diversity. The project includes pilot sites in China, Denmark, the United Kingdom, India, Italy, Mexico, Mongolia, and Paraguay. We present the experience at four field sites and reflect on the project’s initial conception, our collaboration, challenges, progress, and results. We then analyze the different experiences in comparison. We conclude that while we have succeeded in finding viable strategies to avoid contributing to the dynamics of unilateral data extraction as one side of the neocolonial circle, it has been infinitely more difficult to break through the much more subtle but no less powerful mechanisms of paternalism that we find to be prevalent in data-driven North–South relations. These mechanisms, however, can be identified as the other side of the neocolonial circle.</p

    Characterization and Identification of the Basidiomycetous Fungus Associated with 'hoya de malvón' Grapevine Disease in Argentina

    Get PDF
    Inocutis jamaicensis (Murrill) Gottlieb, J.E. Wright & Moncalvo was identified as the basidiomycetous species associated with ‘hoja de malvón’ grapevine disease in Argentina. Macro and micro-morphological characteristics of fruit bodies corresponded to those described for the white-rotting fungus associated with native plant species and Eucalyptus globulus Labill. planted in Uruguay. Monokariotic isolates were obtained from basidiospores produced by fruit bodies of I. jamaicensis collected from Vitis vinifera L. and E. globulus. Dikaryons and fruit bodies produced by pairing monokaryotic mycelium suggest that all these isolates belong to the same species. The analysis of RFLP of the dikaryon produced by pairing monokaryons derived from V. vinifera and E. globulus revealed fragments that corresponded to each monokaryon, confirming that isolates from Vitis mated with those from Eucalyptus. In order to compare grapevine and Uruguayan isolates, RFLPs from ITS region generated by restriction digestion with Alu I, Hae III, Hha I, Msp I and Taq I were performed. Differences found in some restriction pattern could reflect a certain degree of variability between dikariotic isolates, probably related with a particular lifestyle, host specificity or geographic origin

    Curvature effects on the surface thickness and tension at the free interface of 4^4He systems

    Full text link
    The thickness WW and the surface energy σA\sigma_A at the free interface of superfluid 4^4He are studied. Results of calculations carried out by using density functionals for cylindrical and spherical systems are presented in a unified way, including a comparison with the behavior of planar slabs. It is found that for large species WW is independent of the geometry. The obtained values of WW are compared with prior theoretical results and experimental data. Experimental data favor results evaluated by adopting finite range approaches. The behavior of σA\sigma_A and WσAW \sigma_A exhibit overshoots similar to that found previously for the central density, the trend of these observables towards their asymptotic values is examined.Comment: 35 pages, TeX, 5 figures, definitive versio

    Quantum virial expansion approach to thermodynamics of 4^4He adsorbates in carbon nanotube materials: Interacting Bose gas in one dimension

    Full text link
    I demonstrate that 4^4He adsorbates in carbon nanotube materials can be treated as one-dimensional interacting gas of spinless bosons for temperatures below 8 K and for coverages such that all the adsorbates are in the groove positions of the carbon nanotube bundles. The effects of adsorbate-adsorbate interactions are studied within the scheme of virial expansion approach. The theoretical predictions for the specific heat of the interacting adsorbed gas are given.Comment: 5 PS figure

    Lattice model of gas condensation within nanopores

    Full text link
    We explore the thermodynamic behavior of gases adsorbed within a nanopore. The theoretical description employs a simple lattice gas model, with two species of site, expected to describe various regimes of adsorption and condensation behavior. The model includes four hypothetical phases: a cylindrical shell phase (S), in which the sites close to the cylindrical wall are occupied, an axial phase (A), in which sites along the cylinder's axis are occupied, a full phase (F), in which all sites are occupied, and an empty phase (E). We obtain exact results at T=0 for the phase behavior, which is a function of the interactions present in any specific problem. We obtain the corresponding results at finite T from mean field theory. Finally, we examine the model's predicted phase behavior of some real gases adsorbed in nanopores

    Collisionless collective modes of fermions in magnetic traps

    Full text link
    We present a Random-Phase-Approximation formalism for the collective spectrum of two hyperfine species of dilute 40K atoms, magnetically trapped at zero temperature and subjected to a repulsive s-wave interaction between atoms with different spin projections. We examine the density-like and the spin-like oscillation spectra, as well as the transition density profiles created by external multipolar fields. The zero sound spectrum is always fragmented and the density and spin channels become clearly distinguishable if the trapping potentials acting on the species are identical. Although this distinction is lost when these confining fields are different, at selected excitation frequencies the transition densities may display the signature of the channel.Comment: 10 pages, 9 figure

    Specific heats of dilute neon inside long single-walled carbon nanotube and related problems

    Full text link
    An elegant formula for coordinates of carbon atoms in a unit cell of a single-walled nanotube (SWNT) is presented and the potential of neon (Ne) inside an infinitely long SWNT is analytically derived out under the condition of the Lennard-Jones potential between Ne and carbon atoms. Specific heats of dilute Ne inside long (20, 20) SWNT are calculated at different temperatures. It is found that Ne exhibits 3-dimensional (3D) gas behavior at high temperature but behaves as 2D gas at low temperature. Especially, at ultra low temperature, Ne inside (20, 20) nanotubes behaves as lattice gas. A coarse method to determine the characteristic temperature Tc\mathcal{T}_c for low density gas in a potential is put forward. If TTc\mathcal{T}\gg \mathcal{T}_c, we just need to use the classical statistical mechanics without solving the Shr\"{o}dinger equation to consider the thermal behavior of gas in the potential. But if TTc\mathcal{T}\sim \mathcal{T}_c, we must solve the Shr\"{o}dinger equation. For Ne in (20,20) nanotube, we obtain Tc60\mathcal{T}_c\approx 60 K.Comment: 14 pages, 7 figure

    Boson gas in a periodic array of tubes

    Full text link
    We report the thermodynamic properties of an ideal boson gas confined in an infinite periodic array of channels modeled by two, mutually perpendicular, Kronig-Penney delta-potentials. The particle's motion is hindered in the x-y directions, allowing tunneling of particles through the walls, while no confinement along the z direction is considered. It is shown that there exists a finite Bose- Einstein condensation (BEC) critical temperature Tc that decreases monotonically from the 3D ideal boson gas (IBG) value T0T_{0} as the strength of confinement P0P_{0} is increased while keeping the channel's cross section, axaya_{x}a_{y} constant. In contrast, Tc is a non-monotonic function of the cross-section area for fixed P0P_{0}. In addition to the BEC cusp, the specific heat exhibits a set of maxima and minima. The minimum located at the highest temperature is a clear signal of the confinement effect which occurs when the boson wavelength is twice the cross-section side size. This confinement is amplified when the wall strength is increased until a dimensional crossover from 3D to 1D is produced. Some of these features in the specific heat obtained from this simple model can be related, qualitatively, to at least two different experimental situations: 4^4He adsorbed within the interstitial channels of a bundle of carbon nanotubes and superconductor-multistrand-wires Nb3_{3}Sn.Comment: 9 pages, 10 figures, submitte
    corecore