412 research outputs found
Association between Resistin Levels and All-Cause and Cardiovascular Mortality: A New Study and a Systematic Review and Meta-Analysis.
CONTEXT: Studies concerning the association between circulating resistin and mortality risk have reported, so far, conflicting results.
OBJECTIVE: To investigate the association between resistin and both all-cause and cardiovascular (CV) mortality risk by 1) analyzing data from the Gargano Heart Study (GHS) prospective design (n=359 patients; 81 and 58 all-cause and CV deaths, respectively); 2) performing meta-analyses of all published studies addressing the above mentioned associations.
DATA SOURCE AND STUDY SELECTION: MEDLINE and Web of Science search of studies reporting hazard ratios (HR) of circulating resistin for all-cause or CV mortality.
DATA EXTRACTION: Performed independently by two investigators, using a standardized data extraction sheet.
DATA SYNTHESIS: In GHS, adjusted HRs per one standard deviation (SD) increment in resistin concentration were 1.28 (95% CI: 1.07-1.54) and 1.32 (95% CI: 1.06-1.64) for all-cause and CV mortality, respectively. The meta-analyses included 7 studies (n=4016; 961 events) for all-cause mortality and 6 studies (n=4,187: 412 events) for CV mortality. Pooled HRs per one SD increment in resistin levels were 1.21 (95% CI: 1.03-1.42, Q-test p for heterogeneity<0.001) and 1.05 (95% CI: 1.01-1.10, Q-test p for heterogeneity=0.199) for all-cause and CV mortality, respectively. At meta-regression analyses, study mean age explained 9.9% of all-cause mortality studies heterogeneity. After adjusting for age, HR for all-cause mortality was 1.24 (95% CI: 1.06-1.45).
CONCLUSIONS: Our results provide evidence for an association between circulating resistin and mortality risk among high-risk patients as are those with diabetes and coronary artery disease
EXPERIMENTAL ANALYSIS OF PRESSURE DROP IN SINGLE AND TWO PHASE IN MINI CHANNELS
Evaporators with mini and micro channels are one of the main focuses in the design and development of equipment applied to compact refrigeration systems. The objective of this work is to investigate pressure drop of natural refrigerant, isobutane (R-600a), in the single-phase flow through two small tubes, with 1.0 mm and 2.6 mm of internal diameter. Also, the pressure drop was analyzed in the boiling flow in a 2.6 mm internal diameter tube. The experimental tests included mass velocities of 188, 240, 280 and 370 kg/(m²s), heat fluxes in the range from 0 to 134 kW/m² and boiling flow the saturation temperature of 22 ºC and vapor quality up to 0.8. It was possible to observe the significant influence of the diameter and mass velocity on the total pressure drop and the frictional pressure drop, respectively. The experimental frictional pressure drop in flow boiling in 2.6 mm of internal diameter was compared with four different correlations in literature
Electron temperature fluctuations in NGC 346
The existence and origin of large spatial temperature fluctuations in HII
regions and planetary nebulae are assumed to explain the differences between
the heavy element abundances inferred from collisionally excited and
recombination lines, although this interpretation remains significantly
controversial. We investigate the spatial variation in electron temperature
inside NGC 346, the brightest HII region in the Small Magellanic Cloud. Long
slit spectrophotometric data of high signal-to-noise were employed to derive
the electron temperature from measurements derived from localized observations
of the [OIII]( ratio in three
directions across the nebula. The electron temperature was estimated in 179
areas of 5 of size distributed along
three different declinations. A largely homogeneous temperature distribution
was found with a mean temperature of 12 269 K and a dispersion of 6.1%. After
correcting for pure measurements errors, a temperature fluctuation on the plane
of the sky of (corresponding to a dispersion of 4.5%)
was obtained, which indicates a 3D temperature fluctuation parameter of . A large scale gradient in temperature of the order of
K arcsec was found. The magnitude of the temperature
fluctuations observed agrees with the large scale variations in temperature
predicted by standard photoionization models, but is too small to explain the
abundance discrepancy problem. However, the possible existence of small spatial
scale temperature variations is not excluded.Comment: 6 pages, 5 figures, 2 table
An environment to share in-service training on the net: An action-research about charge in primary and middle school
The net was one of the determining factors in a training of a Group of 4 primary and middle school teachers (L. M. in Forni Di Sopra and C. D. F. in Villa Santina, P. C. in Tolmezzo and D. S. in Gemona, all places in the mountains
of Friuli, in the Nord-East of Italy) in an action-research on the electric charge. It was developed through meetings with researchers in physics education and Exchange and sharing of experiences and projects on the net, in an environment designed for teaching activities and under the guidance of a project tutor. The environment allowed to establish different kinds of relations: between teachers, between them and researchers, between classes. It offered to teachers (two in middle school and two in primary school) a place for discussions during the design of paths to be presented to their classes, to structure and share the products of their training both during and after it, to reflect on their training path
Acompañamiento a una comunidad Moquoit en el desarrollo de proyectos productivos agroecológicos
The Rural Soil and Water Directorate dates back to the 1970s within Chaco Ministry of Production. This directorate has been working in action, with small and medium-size producers, focused on field work, rural development, sustainability, soil care, appropriate practices and gender and rurality among others. This publication will outline an experience carried out with the Moqoit. The aim of this work was to provide technical assistance to the development of agroecological productive projects carried out by family and community producers from the Moqoit in El Pastoril, Villa Ángela, Chaco. Theoreticalpractical workshops were held related to agroecological production about sodium soil recovery treatments. As a result, it was possible to turn 0.25 ha unused property into a biodiversity community garden with soil recovery. It is not possible to sustain the processes without the local supporters who go along, monitor and strengthen these processes.La Dirección de suelos y agua rural, data sus inicios desde los años 70, como organismo dentro del Ministerio de Producción- Provincia de Chaco. Se ha caracterizado por la intervención en el territorio, sobre todo con pequeños y medianos productores, focalizados en el trabajo a campo, desarrollo rural, sostenibilidad, cuidado de los suelos, prácticas adecuadas, género y ruralidad, entre otros. En esta publicación se presentará la experiencia en el acompañamiento brindado a una comunidad Moqoit. El objetivo del trabajo fue brindar asistencia técnica para el desarrollo de proyectos productivos agro-ecológicos a productores familiares y comunitarios, de la Moqoit de El Pastoril, Villa Ángela, Chaco. Se realizaron talleres teóricos-prácticos vinculados a la producción agroecológica, con tratamientos de recuperación de suelos, de características sódicas. Como resultados, se logró convertir un predio de 0,25 ha sin utilización, en una huerta comunitaria biodiversa, con recuperación de suelo. No es posible sostener los procesos, sin los actores locales que acompañan, monitorean y fortalecen estos procesos
NGC 2579 and the carbon and oxygen abundance gradients beyond the solar circle
We present deep echelle spectrophotometry of the Galactic HII region NGC
2579. The data have been taken with the Very Large Telescope Ultraviolet-Visual
Echelle Spectrograph in the 3550--10400 \AA\ range. This object, which has been
largely neglected, shows however a rather high surface brightness, a high
ionization degree and is located at a galactocentric distance of 12.4 0.7
kpc. Therefore, NGC 2579 is an excellent probe for studying the behaviour of
the gas phase radial abundance gradients in the outer disc of the Milky Way. We
derive the physical conditions of the nebula using several emission
line-intensity ratios as well as the abundances of several ionic species from
the intensity of collisionally excited lines. We also determine the ionic
abundances of C, O and O -- and therefore the total O
abundance -- from faint pure recombination lines. The results for NGC 2579
permit to extend our previous determinations of the C, O and C/O gas phase
radial gradients of the inner Galactic disc (Esteban etal. 2005) to larger
galactocentric distances. We find that the chemical composition of NGC 2579 is
consistent with flatten gradients at its galactocentric distance. In addition,
we have built a tailored chemical evolution model that reproduces the observed
radial abundance gradients of O, C and N and other observational constraints.
We find that a levelling out of the star formation efficiency about and beyond
the isophotal radius can explain the flattening of chemical gradients observed
in the outer Galactic disc.Comment: 10 pages, 5 figures. Accepted for publication in Monthly Notices of
the Royal Astronomical Societ
Modal Formulation of Segmented Euler-Bernoulli Beams
We consider the obtention of modes and frequencies of segmented
Euler-Bernoulli beams with internal damping and external viscous damping at the
discontinuities of the sections. This is done by following a Newtonian approach
in terms of a fundamental response of stationary beams subject to both types of
damping. The use of a basis generated by the fundamental solution of a differential
equation of fourth-order allows to formulate the eigenvalue problem and to write
the modes shapes in a compact manner. For this, we consider a block matrix that
carries the boundary conditions and intermediate conditions at the beams
and values of the fundamental matrix at the ends and intermediate points of the beam. For
each segment, the elements of the basis have the same shape since they are chosen as a
convenient translation of the elements of the basis for the first segment. Our method
avoids the use of the first-order state formulation also to rely on the Euler basis of
a differential equation of fourth-order and it allows to envision how conditions will
influence a chosen basis
Propagation of ionizing radiation in HII regions: the effects of optically thick density fluctuations
The accepted explanation of the observed dichotomy of two orders of magnitude
between in situ measurements of electron density in HII regions, derived from
emission line ratios, and average measurements based on integrated emission
measure, is the inhomogeneity of the ionized medium. This is expressed as a
"filling factor", the volume ratio of dense to tenuous gas, measured with
values of order 10^-3. Implicit in the filling factor model as normally used,
is the assumption that the clumps of dense gas are optically thin to ionizing
radiation. Here we explore implications of assuming the contrary: that the
clumps are optically thick. A first consequence is the presence within HII
regions of a major fraction of neutral hydrogen. We estimate the mean H^o/H^+
ratio for a population of HII regions in the spiral galaxy NGC 1530 to be the
order of 10, and support this inference using dynamical arguments. The
optically thick clumpy models allow a significant fraction of the photons
generated by the ionizing stars to escape from their HII region. We show, by
comparing model predictions with observations, that these models give an
account at least as good as, and probably better than that of conventional
models, of the radial surface brightness distribution and of selected spectral
line diagnostics for physical conditions within HII regions. These models
explain how an HII region can appear, from its line ratios, to be ionization
bounded, yet permit a major fraction of its ionizing photons to escape.Comment: 9 pages, 7 figures (2 of them in colours), accepted for publication
in A&
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