4,650 research outputs found

    Metabolic risk score indexes validation in overweight healthy people

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    The constellation of adverse cardiovascular disease (CVD) and metabolic risk factors, including elevated abdominal obesity, blood pressure (BP), glucose, and triglycerides (TG) and lowered high-density lipoprotein-cholesterol (HDL-C), has been termed the metabolic syndrome (MetSyn) [1]. A number of different definitions have been developed by the World Health Organization (WHO) [2], the National Cholesterol Education Program Adult Treatment Panel III (ATP III) [3], the European Group for the Study of Insulin Resistance (EGIR) [4] and, most recently, the International Diabetes Federation (IDF) [5]. Since there is no universal definition of the Metabolic Syndrome, several authors have derived different risk scores to represent the clustering of its components [6-11]

    Short-range charge-order in RRNiO3_{3} perovskites (RR=Pr,Nd,Eu) probed by X-ray absorption spectroscopy

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    The short-range organization around Ni atoms in orthorhombic RRNiO3_{3} (RR=Pr,Nd,Eu) perovskites has been studied over a wide temperature range by Ni K-edge x-ray absorption spectroscopy. Our results demonstrate that two different Ni sites, with different average Ni-O bond lengths, coexist in those orthorhombic compounds and that important modifications in the Ni nearest neighbors environment take place across the metal-insulator transition. We report evidences for the existence of short-range charge-order in the insulating state, as found in the monoclinic compounds. Moreover, our results suggest that the two different Ni sites coexists even in the metallic state. The coexistence of two different Ni sites, independently on the RR ion, provides a common ground to describe these compounds and shed new light in the understanding of the phonon-assisted conduction mechanism and unusual antiferromagnetism present in all RRNiO3_{3} compounds.Comment: 4 pages, 3 figures, accepted PRB - Brief Report Dec.200

    Can facilitation influence the spatial genetics of the beneficiary plant population?

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    1. Plant facilitation is a positive interaction where a nurse or nurse plant community alters the local conditions, improving the life-time fitness of other beneficiary plants. In stressful environments, a common consequence is the formation of discrete vegetation patches under nurse plants, surrounded by open space. The consequences of such spatial patterns have been studied mostly at the community level. 2. At the population level, facilitation causes a distribution of beneficiary individuals that could have intra-specific genetic consequences. The spatial patchiness and the increase in local aggregation can potentially affect the population fine-scale genetic structure. In addition, marked microenvironmental differences under nurses versus outside could lead to plastic phenotypic variation between facilitated and non-facilitated individuals, as for example reproductive asynchrony, potentially producing assortative mating. 3. This study tests the hypothesis that plant facilitation can have genetic consequences for the population of a beneficiary plant (Euphorbia nicaeensis) by affecting its spatial genetic structure and mating patterns between subpopulations of facilitated and non-facilitated individuals. 4. Facilitation in this system creates an aggregated distribution of beneficiary individuals compared to a minority of non-facilitated individuals that grow on the open ground. Facilitation also leads to slight phenological differences mediated by strong microenvironmental differences created by nurses compared to the open ground. Yet a molecular analysis showed that, although there is fine scale spatial genetic structure in this system, there is no evidence that it is caused by facilitation. Numerical simulations further showed that spatial genetic patterns in the population are little influenced by the phenological mismatch observed in the field. 5. Synthesis. Facilitation leads to the strong spatial aggregation of beneficiary plants and desynchronizes their flowering phenology, but the magnitude of these effects is not enough to have local genetic consequences in our study system. Facilitation seems thus to have a homogenizing role by allowing the persistence of a diverse gene pool in populations in harsh environments, rather than fomenting genetic differentiation. Further information on other systems where facilitation produces stronger spatial or phenological effects on facilitated plants is needed to fill the large knowledge gap we have on the genetic effects of facilitation

    A comparative analysis of configurations of linear Fresnel collectors for concentrating solar power

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    Linear Fresnel collector arrays present some relevant advantages in the domain of concentrating solar power because of their simplicity, robustness and low capital cost. However, they also present important drawbacks and limitations, notably their average concentration ratio, which seems to limit significantly the performance of these systems. First, the paper addresses the problem of characterizing the mirror field configuration assuming hourly data of a typical year, in reference to a configuration similar to that of Fresdemo. For a proper comparative study, it is necessary to define a comparison criterion. In that sense, a new variable is defined, the useful energy efficiency, which only accounts for the radiation that impinges on the receiver with intensities above a reference value. As a second step, a comparative study between central linear Fresnel reflectors and compact linear Fresnel reflectors is carried out. This analysis shows that compact linear Fresnel reflectors minimize blocking and shading losses compared to a central configuration. However this minimization is not enough to overcome other negative effects of the compact Fresnel collectors, as the greater dispersion of the rays reaching the receiver, caused by the fact that mirrors must be located farther from the receiver, which yields to lower efficiencies

    Static response in disk packings

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    We present experimental and numerical results for displacement response functions in packings of rigid frictional disks under gravity. The central disk on the bottom layer is shifted upwards by a small amount, and the motions of disks above it define the displacement response. Disk motions are measured with the help of a still digital camera. The responses so measured provide information on the force-force response, that is, the excess force at the bottom produced by a small overload in the bulk. We find that, in experiments, the vertical-force response shows a Gaussian-like shape, broadening roughly as the square root of distance, as predicted by diffusive theories for stress propagation in granulates. However, the diffusion coefficient obtained from a fit of the response width is ten times larger than predicted by such theories. Moreover we notice that our data is compatible with a crossover to linear broadening at large scales. In numerical simulations on similar systems (but without friction), on the other hand, a double-peaked response is found, indicating wave-like propagation of stresses. We discuss the main reasons for the different behaviors of experimental and model systems, and compare our findings with previous works.Fil: Moukarzel, Cristian Fernando. CENTRO DE INVESTIGACIÓN Y DE ESTUDIOS AVANZADOS ; INSTITUTO POLITÉCNICO NACIONAL; . Universidad Nacional de San Luis; ArgentinaFil: Pacheco Martínez, Hector. CENTRO DE INVESTIGACIÓN Y DE ESTUDIOS AVANZADOS ; INSTITUTO POLITÉCNICO NACIONAL; . Universidad Nacional de San Luis; ArgentinaFil: Ruiz-Suarez, J. C.. Universidad Nacional de San Luis; Argentina. CENTRO DE INVESTIGACIÓN Y DE ESTUDIOS AVANZADOS ; INSTITUTO POLITÉCNICO NACIONAL;Fil: Vidales, Ana Maria. Universidad Nacional de San Luis; Argentina. CENTRO DE INVESTIGACIÓN Y DE ESTUDIOS AVANZADOS ; INSTITUTO POLITÉCNICO NACIONAL; . Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

    Demography, genetic diversity and expansion load in the colonizing species Leontodon longirostris (Asteraceae) throughout its native range

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    Unravelling the evolutionary processes underlying range expansions is fundamental to understand the distribution of organisms, as well as to predict their future responses to environmental change. Predictions for range expansions include a loss of genetic diversity and an accumulation of deleterious alleles along the expansion axis, which can decrease fitness at the range-front (expansion load). In plants, empirical studies supporting expansion load are scarce, and its effects remain to be tested outside a few model species. Leontodon longirostris is a colonizing Asteraceae with a widespread distribution in the Western Mediterranean, providing a particularly interesting system to gain insight into the factors that can enhance or mitigate expansion load. In this study, we produced a first genome draft for the species, covering 418 Mbp (~53% of the genome). Although incomplete, this draft was suitable to design a targeted sequencing of ~1.5 Mbp in 238 L. longirostris plants from 21 populations distributed along putative colonization routes in the Iberian Peninsula. Inferred demographic history supports a range expansion from southern Iberia around 40,000 years ago, reaching northern Iberia around 25,000 years ago. The expansion was accompanied by a loss of genetic diversity and a significant increase in the proportion of putatively deleterious mutations. However, levels of expansion load in L. longirostris were smaller than those found in other plant species, which can be explained, at least partially, by its high dispersal ability, the self-incompatible mating system, and the fact that the expansion occurred along a strong environmental cline

    Simple analytical model for the magnetophoretic separation of superparamagnetic dispersions in a uniform magnetic gradient

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    Magnetophoresis-the motion of magnetic particles under applied magnetic gradient-is a process of great interest in novel applications of magnetic nanoparticles and colloids. In general, there are two main different types of magnetophoresis processes: cooperative magnetophoresis (a fast process enhanced by particle-particle interactions) and noncooperative magnetophoresis (driven by the motion of individual particles in magnetic fields). In the case of noncooperative magnetophoresis, we have obtained a simple analytical solution which allows the prediction of the magnetophoresis kinetics from particle characterization data (size and magnetization). Our comparison with new experimental results shows good quantitative agreement. In addition, we show the existence of a universal curve onto which all experimental results should collapse after proper rescaling. The range of applicability of the analytical solution is discussed in light of the predictions of a magnetic aggregation model

    Rectification of electronic heat current by a hybrid thermal diode

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    We report the realization of an ultra-efficient low-temperature hybrid heat current rectifier, thermal counterpart of the well-known electric diode. Our design is based on a tunnel junction between two different elements: a normal metal and a superconducting island. Electronic heat current asymmetry in the structure arises from large mismatch between the thermal properties of these two. We demonstrate experimentally temperature differences exceeding 6060 mK between the forward and reverse thermal bias configurations. Our device offers a remarkably large heat rectification ratio up to ∼140\sim 140 and allows its prompt implementation in true solid-state thermal nanocircuits and general-purpose electronic applications requiring energy harvesting or thermal management and isolation at the nanoscale.Comment: 8 pages, 6 color figure

    Family history of breast and ovarian cancer and triple negative subtype in hispanic/latina women.

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    Familial breast and ovarian cancer prevalence was assessed among 1150 women of Mexican descent enrolled in a case-only, binational breast cancer study. Logistic regression was conducted to compare odds of triple negative breast cancer (TNBC) to non-TNBC according to family history of breast and breast or ovarian cancer among 914 of these women. Prevalence of breast cancer family history in a first- and first- or second-degree relative was 13.1% and 24.1%, respectively; that for breast or ovarian cancer in a first-degree relative was 14.9%. After adjustment for age and country of residence, women with a first-degree relative with breast cancer were more likely to be diagnosed with TNBC than non-TNBC (OR=1.98; 95% CI, 1.26-3.11). The odds of TNBC compared to non-TNBC were 1.93 (95% CI, 1.26-2.97) for women with a first-degree relative with breast or ovarian cancer. There were non-significant stronger associations between family history and TNBC among women diagnosed at age <50 compared to ≥50 years for breast cancer in a first-degree relative (P-interaction = 0.14) and a first- or second-degree relative (P-interaction = 0.07). Findings suggest that familial breast cancers are associated with triple negative subtype, possibly related to BRCA mutations in Hispanic/Latina women, which are strongly associated with TNBC. Family history is an important tool to identify Hispanic/Latina women who may be at increased risk of TNBC, and could benefit from prevention and early detection strategies

    Synthesis, thermogravimetric and high temperature X-ray diffraction analyses of zinc-substituted nickel manganites

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    Stoichiometric spinel phases Mn2.352xNi0.65ZnxO4 were prepared by thermal decomposition of mixed oxalate precursor powders Mn0.782aNi0.22ZnaC2O4znH2O (with 0 # a # 0.53) at 900°C. Cation-deficient phases Mn2.352xNi0.65Znxh3d/4O41d were identified in the temperature range 350–500°C. The nonstoichiometric coefficient d was found to strongly depend on the zinc content and the decomposition temperature. We showed that the introduction of zinc into the spinel phase enlarges the stability domain of the structure and inhibits oxidation at least up to 900°C. A cubic single-phase was observed for x # 1.00. The lattice parameter variation of the oxides in the composition range 0 # x # 0.60 can be explained using Poix’s method, in terms of the distribution of Zn21 cations on the tetrahedral sites. However, for higher zinc content (x . 0.6) a detailed analysis of data showed that a small fraction of Zn21 is located on octahedral sites
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