2,556 research outputs found

    Quantile contours and allometric modelling for risk classification of abnormal ratios with an application to asymmetric growth-restriction in preterm infants

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    We develop an approach to risk classification based on quantile contours and allometric modelling of multivariate anthropometric measurements. We propose the definition of allometric direction tangent to the directional quantile envelope, which divides ratios of measurements into half-spaces. This in turn provides an operational definition of directional quantile that can be used as cutoff for risk assessment. We show the application of the proposed approach using a large dataset from the Vermont Oxford Network containing observations of birthweight (BW) and head circumference (HC) for more than 150,000 preterm infants. Our analysis suggests that disproportionately growth-restricted infants with a larger HC-to-BW ratio are at increased mortality risk as compared to proportionately growth-restricted infants. The role of maternal hypertension is also investigated.Comment: 31 pages, 3 figures, 8 table

    Group-blind detection with very large antenna arrays in the presence of pilot contamination

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    Massive MIMO is, in general, severely affected by pilot contamination. As opposed to traditional detectors, we propose a group-blind detector that takes into account the presence of pilot contamination. While sticking to the traditional structure of the training phase, where orthogonal pilot sequences are reused, we use the excess antennas at each base station to partially remove interference during the uplink data transmission phase. We analytically derive the asymptotic SINR achievable with group-blind detection, and confirm our findings by simulations. We show, in particular, that in an interference-limited scenario with one dominant interfering cell, the SINR can be doubled compared to non-group-blind detection.Comment: 5 pages, 4 figure

    Genetic variation patterns in some groups of Centaurea (Asteraceae) in Italy

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    In the current work the data of the isozyme analysis of all the twenty studied Italian Centaurea taxa were compared. They belong to Centaurea parlatoris, C. cineraria, C. tenorei and C. jacea groups. The following parameters of the genetic variability were considered: the total number of the alleles, the mean number of alleles per locus (A), the mean percentage of polymorphic loci (P95), the expected heterozygosity (He) that is a measure of the intra-population diversity, the Wright’s fixation index (F) and inbreeding coefficient (FIS) that are measures for the deviation from the Hardy-Weinberg equilibrium. The present study contributes to insight some aspects of the genetic diversity related to the distribution range (endemics or widespread taxa) of the studied Centaurea species. The mean proportion of polymorphic loci and the mean number of alleles per locus (A) in the endemic species are comparable with the widespread ones, while the intra-population diversity (He) results about 40% higher in the populations of the widespread taxa than the endemics. The loci with a major role for the processes of differentiation and evolution of the genus Centaurea in South Italy and Sicily are: Mdh-1, Pgi-2 and Idh-1. Italian Centaurea species with the highest genetic diversity usually inhabit extreme habitats (rocky, sandy places, etc.) and localities with significant human impact or the borderline of their area of distribution. Sicily could be considered a centre of differentiation of the endemic groups of C. cineraria and C. parlatoris which show relatively high intra-population variability

    Energy Efficiency of Distributed Signal Processing in Wireless Networks: A Cross-Layer Analysis

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    In order to meet the growing mobile data demand, future wireless networks will be equipped with a mulitude of access points (APs). Besides the important implications for the energy consumption, the trend towards densification requires the development of decentralized and sustainable radio resource management techniques. It is critically important to understand how the distribution of signal processing operations affects the energy efficiency of wireless networks. In this paper, we provide a cross-layer framework to evaluate and compare the energy efficiency of wireless networks under different levels of distribution of the signal processing load: 1) hybrid, where the signal processing operations are shared between nodes and APs; 2) centralized, where signal processing is entirely implemented at the APs; and 3) fully distributed, where all operations are performed by the nodes. We find that in practical wireless networks, hybrid signal processing exhibits a significant energy efficiency gain over both centralized and fully distributed approaches

    A GIANT ANEURYSM OF PROPER HEPATIC ARTERY IN A CRYOGLOBULINEMIC PATIENT ON HEMODIALYSIS: A CASE REPORT.

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    Introductrion. Hepatic artery aneurysms (HAAs) are unusual vascular lesions often associated with many different pathological conditions. Most of reported cases are described in association with connective tissue diseases, such as polyarteritis nodosa and systemic lupus erythematosus. Case report. We observed a 52-year-old man with hypertension and HCV-related cryoglobulinemia complicated by end stage renal disease on replacement therapy by hemodialysis. He was admitted to our hospital because of the worsening of blood pressure values (170/110 mmHg) associated to new onset abdominal pain. After an initial physical examination, that showed a periumbelical bruit associated to a pulsatile mass in right hypocondrium, an abdominal ultrasound was performed with evidence of aneurysms of both the right branch (diameter max 4,5 cm) and the left branch (diameter max 1.5 cm) of the hepatic artery. An abdominal CT study was also performed and it confirmed the diagnosis of right intrahepatic artery aneurysm with partially thrombosed area in its peripheral distal portion. Discussion. Many different factors can contribute to the aneurysm formation in this patient. Vasculitic involvement due to cryoglobulinemic disease, therapy with steroid drugs, inflammatory state associated to HCV-related hepatitis, chronic kidney disease and replacement therapy by hemodialysis may all be involved in the development of the aneurysmatic hepatic lesion

    New Experimental Constraints on Non-Newtonian Forces below 100 microns

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    We have searched for large deviations from Newtonian gravity by means of a microcantilever-based Cavendish-style experiment. Our data eliminate from consideration mechanisms of deviation that posit strengths ~10^4 times Newtonian gravity at length scales of 20 microns. This measurement is 3 orders of magnitude more sensitive than others that provide constraints at similar length scales.Comment: 4 pages, 4 figure
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