2,735 research outputs found

    Effects of Forest Fires on Flood Frequency Curves in a Mediterranean Catchment/Effets d'incendies de for�t sur les courbes de fr�quence de crue dans un bassin versant M�diterran�en

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    The effect of land-use change on the flood frequency curve (FFC) in a natural catchment is analysed. To achieve this, a simple methodology for the derivation of FFCs in land-use change scenarios is proposed. The adopted methodology, using a stochastic model in Monte Carlo simulation of FFCs, was found to provide a useful framework for detecting changes in flood magnitudes in both pre- and post-fire conditions. In particular, the importance of the antecedent soil moisture condition in the determination of the flood frequency distribution was analysed. The analysis of FFCs for pre- and post-fire conditions shows an increase in the average value of Curve Number and a decrease in the catchment time lag. The derivation of FFCs shows a clear increase in flood quantiles. For the post-fire conditions, the FFC exhibits higher quantiles of the peak discharges showing a reduction in frequency of occurrence. This variation is more significant for low-return period quantiles than for high-return period quantiles. The results of the catchment studies reported here support the hypothesis that the hydrological response of the watershed changes as a result of fire, especially during the first years following a fire event

    Mathematical modelling of HIV-1 dynamics in vivo

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    The influence of the media on COPD patients’ knowledge regarding cardiopulmonary resuscitation

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    Stefano Nava1, Carmen Santoro1, Mario Grassi2, Nicholas Hill31Respiratory Unit, Fondazione S Maugeri, I R C C S Istituto Scientifico di Pavia, Pavia, Italy; 2Department of Health Sciences, Section of Medical Statistics and Epidemiology, University of Pavia, Pavia, Italy; 3Pulmonary and Critical Care Division, Tufts University, New England Medical Center, Boston, MA, USABackground: The decision whether or not to undertake cardiopulmonary resuscitation (CPR) is a major ethical challenge. Patient preferences may be influenced by multiple factors, including information given by the media.Objectives: We wanted to assess whether patients’ knowledge about CPR survival and outcomes was related to presentation by the media.Methods: 100 consecutive patients with COPD and chronic respiratory failure (CRF) and 100 patients at their first hospital admission for respiratory problems were enrolled. A questionnaire was administered to the patients seeking to ascertain their exposure to health information from the media, and to obtain their opinions on 1) the probability of survival after CPR, 2) the maximal length of time from collapse to CPR that allows a reasonable chance of survival, and 3) long-term outcomes of CPR survivors.Results: The patients overestimated the success rate of CPR (63% of them estimated a hospital survival >40%), while the estimate of long-term outcome and timing of the procedure were more realistic. Bivariate correlations analysis showed significant correlation between the rate of correct responses and the viewing of educational television programs (p = 0.039), but not medical stories, reading of health-oriented newspapers, use of the internet, age, educational level, and the presence of CRF.Conclusions: In conclusion, we have shown that both COPD and “newly admitted” patients’ estimate of survival after CPR is much higher than reported by the current literature. A correct knowledge of CPR procedures and outcomes is significantly correlated with the exposure to “educational” medical TV programs, but not medical stories, newspapers, or internet sources.Keywords: cardiopulmonary resuscitation, chronic respiratory failure, chronic obstructive pulmonary disease, media, televisio

    Quantum Annealing for Neural Network optimization problems: a new approach via Tensor Network simulations

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    Quantum Annealing (QA) is one of the most promising frameworks for quantum optimization. Here, we focus on the problem of minimizing complex classical cost functions associated with prototypical discrete neural networks, specifically the paradigmatic Hopfield model and binary perceptron. We show that the adiabatic time evolution of QA can be efficiently represented as a suitable Tensor Network. This representation allows for simple classical simulations, well-beyond small sizes amenable to exact diagonalization techniques. We show that the optimized state, expressed as a Matrix Product State (MPS), can be recast into a Quantum Circuit, whose depth scales only linearly with the system size and quadratically with the MPS bond dimension. This may represent a valuable starting point allowing for further circuit optimization on near-term quantum devices

    Lattice dynamics of dense lithium.

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    We report low-frequency high-resolution Raman spectroscopy and ab-initio calculations on dense lithium from 40 to 200 GPa at low temperatures. Our experimental results reveal rich first-order Raman activity in the metallic and semiconducting phases of lithium. The computed Raman frequencies are in excellent agreement with the measurements. Free energy calculations provide a quantitative description and physical explanation of the experimental phase diagram only when vibrational effect are correctly treated. The study underlines the importance of zero-point energy in determining the phase stability of compressed lithium

    Insights into the role of deep-sea squids of the genus Histioteuthis (Histioteuthidae) in the life cycle of ascaridoid parasites in the Central Mediterranean Sea waters

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    Ascaridoid nematodes comprise a wide range of heteroxenous parasites infecting top fish predators and marine mammals as definitive hosts, with crustaceans, squids, and fishes acting as intermediate/paratenic hosts. Limited data exist on the species and role of several intermediate and paratenic hosts in the life cycle of these parasites. In the aim of adding knowledge on the role of squid species in their life cycle, we have here investigated the larval ascaridoid nematodes collected from the deep-sea umbrella squid Histioteuthis bonnelli and the reverse jewel squid Histioteuthis reversa captured in the Central Mediterranean Sea (Tyrrhenian Sea). Morphological study and sequence analysis of the internal transcribed spacer (ITS) regions of the ribosomal DNA (rDNA) and the mitochondrial cytochrome c oxidase subunit 2 (mtDNA cox2) gene locus revealed the occurrence of Anisakis physeteris and of an unidentified species of the genus Lappetascaris. Sequence analysis revealed that specimens of Lappetascaris from both squid species matched at 100% sequences previously deposited in GenBank from larval ascaridoids collected in octopuses of the genus Eledone of the Mediterranean Sea. The Bayesian inference tree topology obtained from the analysis of the fragments amplified showed that Lappetascaris specimens were included in a major clade comprising Hysterothylacium species collected in fishes of the families Xiphiidae and Istiophoridae. As regards the site of infection in the squid host species, A. physeteris larvae predominated (60.7%) in the gonads, while those of Lappetascaris (76.3%) were found infecting the mantle musculature. The overall high values of parasitic load suggest both squid species as transmitting hosts of third stage larvae of Lappetascaris to top predator fishes, as well as the umbrella squid as an intermediate/paratenic host in the life cycle of A. physeteris in the Mediterranean Sea
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