300 research outputs found
Effects of an aquagym training in postmepausal women
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
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
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
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 He systems
The thickness and the surface energy at the free interface of
superfluid He 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 is independent of the geometry. The obtained
values of are compared with prior theoretical results and experimental
data. Experimental data favor results evaluated by adopting finite range
approaches. The behavior of and 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 He adsorbates in carbon nanotube materials: Interacting Bose gas in one dimension
I demonstrate that He 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
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
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
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
for low density gas in a potential is put forward. If
, 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 , we
must solve the Shr\"{o}dinger equation. For Ne in (20,20) nanotube, we obtain
K.Comment: 14 pages, 7 figure
Boson gas in a periodic array of tubes
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 as the
strength of confinement is increased while keeping the channel's cross
section, constant. In contrast, Tc is a non-monotonic function of
the cross-section area for fixed . 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: He adsorbed within the
interstitial channels of a bundle of carbon nanotubes and
superconductor-multistrand-wires NbSn.Comment: 9 pages, 10 figures, submitte
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