668 research outputs found

    Drug-eluting Microspheres Compared to Conventional Transarterial Chemoembolization as First Line Treatment for Unresectable Hepatocellular Carcinoma: A Single-center Retrospective Cost-utility Analysis

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    Purpose: To assess the cost-utility of initial treatment with drug-eluting microspheres (DEM) transarterial chemoembolization (TACE) versus conventional (C)-TACE in patients with hepatocellular carcinoma considering the perspective of a Local Healthcare Authority in Italy. Materials and methods: The economic evaluation is based on a retrospective single-center study and individual patients' data whose details have been previously reported. The impact of initial treatment with DEM-TACE or C-TACE on disease progression, mortality, and direct health costs over a lifetime horizon were simulated and compared in terms of incremental cost-utility ratio expressed as costs per quality adjusted life years (QALY). Costs included direct health costs related to the first chemoembolization procedure and all subsequent follow-up costs associated with health care resources used for disease management. Probabilistic (PSA) sensitivity analysis was used to assess the robustness of the results. Results: A total of 101 patients in each treatment group were considered. All over the time-horizon median costs were €3,145.14 and €2,158.32 in the DEM-TACE and C-TACE group, respectively (p < 0.001); while mean costs were € 24,619 and € 17,001, respectively (p < 0.001). The ICUR was 6,461.86 €/QALY when using median costs derived from the study population as input for the health-economic evaluation and 49,932.15 €/QALY when the mean costs were considered. Results from PSA highlighted that using median costs DEM-TACE was always cost-effective, while using mean costs, it was preferable only 24.7% of times. Conclusions: The higher prices of DEMs are counterbalanced by the positive impact on QALY

    Rational Approximate Symmetries of KdV Equation

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    We construct one-parameter deformation of the Dorfman Hamiltonian operator for the Riemann hierarchy using the quasi-Miura transformation from topological field theory. In this way, one can get the approximately rational symmetries of KdV equation and then investigate its bi-Hamiltonian structure.Comment: 14 pages, no figure

    Past and Present Environmental Factors Differentially Influence Genetic and Morphological Traits of Italian Barbels (Pisces: Cyprinidae)

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    Local adaptation and phenotypic plasticity can lead to environment-related morphological and genetic variations in freshwater fish. Studying the responses of fish to environmental changes is crucial to understand their vulnerability to human-induced changes. Here, we used a latitudinal gradient as a proxy for past and present environmental factors and tested its influences on both genetic and morphological patterns. We selected as a suitable biogeographic model, the barbels, which inhabit 17 Adriatic basins of the central-southern Italian Peninsula, and explored association among attributes from genetic, morphological, and environmental analyses. The analysis of the mitochondrial DNA control region evidenced a southward significant increase in the number of private haplotypes, supporting the isolation of the southernmost populations related to the Mio-Pleistocene events. In contrast, morphology was mainly affected by changes in the present environmental conditions. Particularly, the number of scales and fish coloration were clearly associated to latitude, and thus thermal and hydrological conditions. Other morphometric and functional traits varied under the selective pressure of other environmental factors like elevation and distance from headwater. These results highlight the sensitivity of barbels to climate changes, which can serve as a basis for future eco-evolutionary and conservation studies

    Flat bidifferential ideals and semihamiltonian PDEs

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    In this paper we consider a class of semihamiltonian systems characterized by the existence of a special conservation law. The density and the current of this conservation law satisfy a second order system of PDEs which has a natural interpretation in the theory of flat bifferential ideals. The class of systems we consider contains important well-known examples of semihamiltonian systems. Other examples, like genus 1 Whitham modulation equations for KdV, are related to this class by a reciprocal trasformation.Comment: 18 pages. v5: formula (36) corrected; minor change

    Identifying the first generation of radio powerful AGN in the Universe with the SKA

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    One of the most challenging and exciting subjects in modern astrophysics is that of galaxy formation at the epoch of reionisation. The SKA, with its revolutionary capabilities in terms of frequency range, resolution and sensitivity, will allow to explore the first Gyr of structure formation in the Universe, in particular, with the detection and study of the earliest manifestations of the AGN phenomenon. The tens of QSOs that are currently known out to the highest redshifts (z 7), many of them exhibiting powerful radio emission, imply that super-massive black holes can be grown on a very short timescale and support the existence of very high redshift (z > 7) radio loud sources - sources that have so far escaped detection. Not only would such detections be paramount to the understanding of the earliest stages of galaxy evolution, they are necessary for the direct study of neutral hydrogen in the Epoch of Reionisation, through observations of the HI 21cm forest against such background sources. In order to understand how SKA and SKA1 observations can be optimised to reveal these earliest AGN, we have examined the effect of a hot CMB on the emission of powerful and young radio galaxies. By looking at the SKA1 capabilities, in particular in terms of wavelength coverage and resolution, we determine how the effects of "CMB-muting" of a radio loud source can be observationally minimised and how to identify the best highest-redshift radio candidates. Considering different predictions for the space density of radio loud AGN at such redshifts, we identify the survey characteristics necessary to optimize the detection and identification of the very first generation of radio loud AGN in the Universe

    On bi-Hamiltonian deformations of exact pencils of hydrodynamic type

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    In this paper we are interested in non trivial bi-Hamiltonian deformations of the Poisson pencil \omega_{\lambda}=\omega_2+\lambda \omega_1=u\delta'(x-y)+\f{1}{2}u_x\delta(x-y)+\lambda\delta'(x-y). Deformations are generated by a sequence of vector fields {X2,X4,...}\{X_2, X_4,...\}, where each X2kX_{2k} is homogenous of degree 2k2k with respect to a grading induced by rescaling. Constructing recursively the vector fields X2kX_{2k} one obtains two types of relations involving their unknown coefficients: one set of linear relations and an other one which involves quadratic relations. We prove that the set of linear relations has a geometric meaning: using Miura-quasitriviality the set of linear relations expresses the tangency of the vector fields X2kX_{2k} to the symplectic leaves of ω1\omega_1 and this tangency condition is equivalent to the exactness of the pencil ωλ\omega_{\lambda}. Moreover, extending the results of [17], we construct the non trivial deformations of the Poisson pencil ωλ\omega_{\lambda}, up to the eighth order in the deformation parameter, showing therefore that deformations are unobstructed and that both Poisson structures are polynomial in the derivatives of uu up to that order.Comment: 34 pages, revised version. Proof of Theorem 16 completely rewritten due to an error in the first versio

    Morphologic and genetic variability in the Barbus fishes (Teleostei, Cyprinidae) of Central Italy

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    © 2019 Royal Swedish Academy of Sciences Italian freshwaters are highly biodiverse, with species present including the native fishes Barbus plebejus and Barbus tyberinus that are threatened by habitat alteration, fish stocking and invasive fishes, especially European barbel Barbus barbus. In central Italy, native fluvio-lacustrine barbels are mainly allopatric and so provide an excellent natural system to evaluate the permeability of the Apennine Mountains. Here, the morphologic and genetic distinctiveness was determined for 611 Barbus fishes collected along the Padany–Venetian (Adriatic basins; PV) and Tuscany–Latium (Tyrrhenian basins; TL) districts. Analyses of morphological traits and mitochondrial DNA sequence data explored the natural and anthropogenic factors that have shaped their distribution ranges. Over 100 alien B. barbus were recorded in the Tiber basin (TL district) and Metauro basin (PV district). Comparisons of genetic and morphometric data revealed that morphometric data could identify alien B. barbus from native Barbus, but could not differentiate between B. tyberinus and B. plebejus. Genetic analyses revealed ~50 D-loop mtDNA haplotypes and identified a distinct Barbus lineage present only in the Vomano River at the southern boundary of PV district. Demographic expansion and molecular variance analyses revealed a lack of geographic structuring across the sampling regions. While the contemporary B. plebejus distribution has been driven primarily by anthropogenic fish translocations, the dispersal of B. tyberinus has been via natural dispersion, including their crossing of the Apennine Mountains via temporary river connectivity. The results also revealed that the Barbus fishes of the mid-Adriatic region of Europe have a complex pattern of local endemism. To conserve these patterns of genetic uniqueness, especially in the mid-Adriatic basins, Barbus fishes should be managed by treating them as unique evolutionary units and ceasing translocations of all Barbus fishes between river basins
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