1,638 research outputs found

    Statistical model for intermittent plasma edge turbulence

    Full text link
    The Probability Distribution Function of plasma density fluctuations at the edge of fusion devices is known to be skewed and strongly non-Gaussian. The causes of this peculiar behaviour are, up to now, largely unexplored. On the other hand, understanding the origin and the properties of edge turbulence is a key issue in magnetic fusion research. In this work we show that a stochastic fragmentation model, already successfully applied to fluid turbulence, is able to predict an asymmetric distribution that closely matches experimental data. The asymmetry is found to be a direct consequence of intermittency. A discussion of our results in terms of recently suggested BHP universal curve [S.T. Bramwell, P.C.W. Holdsworth, J.-F. Pinton, Nature (London) 396, 552 (1998)], that should hold for strongly correlated and critical systems, is also proposedComment: 13 pages. Physica Review E, accepte

    About the parabolic relation existing between the skewness and the kurtosis in time series of experimental data

    Full text link
    In this work we investigate the origin of the parabolic relation between skewness and kurtosis often encountered in the analysis of experimental time-series. We argue that the numerical values of the coefficients of the curve may provide informations about the specific physics of the system studied, whereas the analytical curve per se is a fairly general consequence of a few constraints expected to hold for most systems.Comment: To appear in Physica Script

    Numerical cubature on scattered data by adaptive interpolation

    Full text link
    We construct cubature methods on scattered data via resampling on the support of known algebraic cubature formulas, by different kinds of adaptive interpolation (polynomial, RBF, PUM). This approach gives a promising alternative to other recent methods, such as direct meshless cubature by RBF or least-squares cubature formulas

    Relationships between population traits, nonstructural carbohydrates, and elevation in alpine stands of Vaccinium myrtillus

    Get PDF
    Premise: Despite great attention given to the relationship between plant growth and carbon balance in alpine tree species, little is known about shrubs at the treeline. We hypothesized that the pattern of main nonstructural carbohydrates (NSCs) across elevations depends on the interplay between phenotypic trait plasticity, plant\u2013plant interaction, and elevation. Methods: We studied the pattern of NSCs (i.e., glucose, fructose, sucrose, and starch) in alpine stands of Vaccinium myrtillus (above treeline) across an elevational gradient. In the same plots, we measured key growth traits (i.e., anatomical stem features) and shrub cover, evaluating putative relationships with NSCs. Results: Glucose content was positively related with altitude, but negatively related with shrub cover. Sucrose decreased at high altitude and in older populations and increased with higher percentage of vascular tissue. Starch content increased at middle and high elevations and in stands with high shrub cover. Moreover, starch content was negatively related with the number of xylem rings and the percentage of phloem tissue, but positively correlated with the percentage of xylem tissue. Conclusions: We found that the increase in carbon reserves across elevations was uncoupled from plant growth, supporting the growth limitation hypothesis, which postulates NSCs accumulate at high elevation as a consequence of low temperature. Moreover, the response of NSC content to the environmental stress caused by elevation was buffered by phenotypic plasticity of plant traits, suggesting that, under climate warming conditions, shrub expansion due to enhanced plant growth would be pronounced in old but sparse stands

    Multidimensional prognostic index and mortality in intermediate care facilities: A retrospective study

    Get PDF
    Multidimensional prognostic index (MPI) is a frailty assessment tool used for stratifying prognosis in older hospitalized people, but data regarding older people admitted to intermediate care facilities (ICFs) are missing. The aim of this study is to evaluate whether MPI can predict mortality in older patients admitted to the ICFs. MPI was calculated using different domains explored by a standard comprehensive geriatric assessment and categorized into tertiles (MPI-1 ≤ 0.20, MPI 2 0.20–0.34, MPI 3 > 0.34). A Cox’s regression analysis, taking mortality as the outcome, was used, reporting the results as hazard ratios (HRs) with 95% confidence intervals (CIs). In total, 653 older patients were enrolled (mean age: 82 years, 59.1% females). Patients in MPI-2 (HR = 3.66; 95%CI: 2.45–5.47) and MPI-3 (HR = 6.22; 95%CI: 4.22–9.16) experienced a higher risk of mortality, compared to MPI-1. The accuracy of MPI in predicting mortality was good (area under the curve (AUC) = 0.74, 95%CI: 0.70–0.78). In conclusion, our study showed that prognostic stratification, as assessed by the MPI, was associated with a significantly different risk of mortality in older patients admitted to the ICFs, indicating the necessity of using a CGA-based tool for better managing older people in this setting as well. © 2021 by the authors. Licensee MDPI, Basel, Switzerland

    Relationship between soluble receptor for advanced glycation end products (sRAGE), body composition and fat distribution in healthy women

    Get PDF
    Purpose: Soluble receptor for advanced glycation end products (sRAGE) is a decoy receptor which sequesters RAGE ligands and acts as a cytoprotective agent. To date, it is unclear whether the lower sRAGE levels observed in obesity are a marker of increased overall adiposity or reflect increases in particular fat depots. Therefore, we evaluated in healthy women the relationship among sRAGE and indicators of adiposity, including abdominal visceral (VAT) and epicardial visceral (EAT) adipose tissues, to explore the potential role of sRAGE as an earlier biomarker of cardiometabolic risk. Methods: Plasma sRAGE levels were quantified by an enzyme-linked immunosorbent assay in 47 healthy women. Total fat mass (FM) and fat-free mass were estimated with bioimpedance analysis. Anthropometric measures and biochemical data were recorded. Subcutaneous adipose tissue, VAT and EAT volumes were measured by magnetic resonance imaging. Results: Obese women had lower sRAGE levels compared to normal-weight women. sRAGE levels were also lower in women with a waist circumference (WC) larger than 80 cm. Correlation analyses indicated an inverse association of sRAGE with body mass index and FM. Concerning adipose tissue distribution, sRAGE inversely correlated with WC, EAT and VAT depots. In a multiple stepwise regression analysis, performed to emphasize the role of fat distribution, EAT volume was the only predictor of sRAGE. Conclusions: Lower sRAGE levels reflect accumulation of visceral fat mainly at the epicardial level and are present in advance of metabolic complications in adult women. sRAGE quantification might be an early marker of cardiometabolic risk

    Identification and localization of the bilitranslocase homologue in white grape berries (Vitis vinifera L.) during ripening

    Get PDF
    A homologue of the mammalian bilirubin transporter bilitranslocase (BTL) (TCDB 2.A.65.1.1), able to perform an apparent secondary active transport of flavonoids, has previously been found in carnation petals and red grape berries. In the present work, a BTL homologue was also shown in white berries from Vitis vinifera L. cv. Tocai/Friulano, using anti-sequence antibodies specific for rat liver BTL. This transporter, similarly to what found in red grape, was localized in the first layers of the epidermal tissue and in the vascular bundle cells of the mesocarp. In addition, a strong immunochemical reaction was detected in the placental tissue and particularly in peripheral integuments of the seed. The protein was expressed during the last maturation stages in both skin and pulp tissues and exhibited an apparent molecular mass of c. 31 kDa. Furthermore, the transport activity of such a carrier, measured as bromosulphophthalein (BSP) uptake, was detected in berry pulp microsomes, where it was inhibited by specific anti-BTL antibodies. The BTL homologue activity exhibited higher values, for both Km and Vmax, than those found in the red cultivar. Moreover, two non-pigmented flavonoids, such as quercetin (a flavonol) and eriodictyol (a flavanone), inhibited the uptake of BSP in an uncompetitive manner. Such results strengthen the hypothesis that this BTL homologue acts as a carrier involved also in the membrane transport of colourless flavonoids and demonstrate the presence of such a carrier in different organs and tissues

    The dust-scattering X-ray rings of the anomalous X-ray pulsar 1E 1547.0-5408

    Get PDF
    On 2009 January 22 numerous strong bursts were detected from the anomalous X-ray pulsar 1E 1547.0-5408. Swift/XRT and XMM-Newton/EPIC observations carried out in the following two weeks led to the discovery of three X-ray rings centered on this source. The ring radii increased with time following the expansion law expected for a short impulse of X-rays scattered by three dust clouds. Assuming different models for the dust composition and grain size distribution, we fit the intensity decay of each ring as a function of time at different energies, obtaining tight constrains on the distance of the X-ray source. Although the distance strongly depends on the adopted dust model, we find that some models are incompatible with our X-ray data, restricting to 4-8 kpc the range of possible distances for 1E 1547.0-5408. The best-fitting dust model provides a source distance of 3.91 +/- 0.07 kpc, which is compatible with the proposed association with the supernova remnant G 327.24-0.13, and implies distances of 2.2 kpc, 2.6 kpc and 3.4 kpc for the dust clouds, in good agreement with the dust distribution inferred by CO line observations towards 1E 1547.0-5408. However, dust distances in agreement with CO data are also obtained for a set of similarly well-fitting models that imply a source distance of about 5 kpc. A distance of about 4-5 kpc is also favored by the fact that these dust models are already known to provide good fits to the dust-scattering halos of bright X-ray binaries.Comment: Accepted for publication in The Astrophysical Journal; 10 pages in emulate-apj style, 3 tables, 5 color figures. Note: abstract truncated; full abstract in the pape

    Physiological characterization of common bean (Phaseolus vulgaris L.) genotypes, water-stress induced with contrasting response towards drought.

    Get PDF
    Among the three annual common bean seasons in Brazil, two of them are subject to drought. The objective of this study was to identify physiological traits in common bean under water restriction. The common beans genotypes, BAT 477 (tolerant to water-stress) and Perola (sensitive to water-stress), were grown under greenhouse conditions under two different watering regimes: irrigated (control treatment) and non-irrigated (stress treatment). The water deficit treatment consisted of suspension of irrigation to the plants at 10 days after emergence (DAE) (at the V2 physiological stage) for 30 days, followed by the irrigation?s re-establishment at 40 DAE (at the R6-R7 physiological stage) up to the phase of physiological maturity of the grains for assessment of grain yield and production components. Under water-stress, BAT 477 showed less reduction in grain yield (33%), more capacity for osmotic adjustment (0.30 MPa) and superiority in the root system´s development (~50%) compared to Perola that showed a 53% reduction in the grain yield and 0.06 MPa of osmotic adjustment. In this study, the robustness of the root system and osmotic adjustment are the main physiological indicators of tolerance to water deficit in common bean plants
    corecore