1,013 research outputs found

    Upper bounds for the eigenvalues of Hessian equations

    Full text link
    We prove some upper bounds for the Dirichlet eigenvalues of a class of fully nonlinear elliptic equations, namely the Hessian equationsComment: 15 pages, 1 figur

    A sharp estimate for Neumann eigenvalues of the Laplace-Beltrami operator for domains in a hemisphere

    Get PDF
    Here, we prove an isoperimetric inequality for the harmonic mean of the first N - 1 non-trivial Neumann eigenvalues of the Laplace-Beltrami operator for domains contained in a hemisphere of N

    Papia civitas gloriosa: urban geomorphology for a thematic itinerary on geocultural heritage in Pavia (Central Po Plain, N Italy)

    Get PDF
    The interaction between geomorphological processes and anthropogenic activities produces an impressive association of geomorphological and archaeological heritage in urban contexts. We analyzed the urban geomorphology and the geo- and cultural heritage in the town of Pavia (N Italy). The city is located in a strategic position, on a series of fluvial terraces where the Romans founded a colony, probably in the place of an Iron Age Gaul settlement. In Medieval Times and the Modern Era, Pavia sprawled outside the Roman walls, creating new urban areas and modifying the landscape. Geomorphological and GIS-spatial analyses integrated with anthropic landform surveying, archaeological data and historical cartography were performed. This multi-disciplinary approach allowed an investigation into how urban development was firstly adapted and then superimposed onto fluvial landforms. As a result, a flexible geocultural itinerary is proposed for linking geoheritage with cultural heritage, and for disseminating urban geomorphology key-concepts

    49Cr: Towards full spectroscopy up to 4 MeV

    Full text link
    The nucleus 49Cr has been studied analysing gamma-gamma coincidences in the reaction 46Ti(alpha,n)49Cr at the bombarding energy of 12 MeV. The level scheme has been greatly extended at low excitation energy and several new lifetimes have been determined by means of the Doppler Shift Attenuation Method. Shell model calculations in the full pf configuration space reproduce well negative-parity levels. Satisfactory agreement is obtained for positive parity levels by extending the configuration space to include a nucleon-hole either in the 1d3/2 or in the 2s1/2 orbitals. A nearly one-to-one correspondence is found between experimental and theoretical levels up to an excitation energy of 4 MeV. Experimental data and shell model calculations are interpreted in terms of the Nilsson diagram and the particle-rotor model, showing the strongly coupled nature of the bands in this prolate nucleus. Nine values of K(pi) are proposed for the levels observed in this experiment. As a by-result it is shown that the values of the experimental magnetic moments in 1f7/2 nuclei are well reproduced without quenching the nucleon g-factors.Comment: 13 pages, 8 figure

    Demand for the quality conservation of Venice, Italy, according to different nationalities.

    Get PDF
    This paper focuses on visitor demand for the quality conservation of Venice according to different nationalities. The vast majority of visitors to Venice are foreigners (both tourists and day-visitors) who come from all over the world. In this research they are mainly categorized as non-Italian Europeans or non-Europeans. A specific theoretical model, in which quality conservation is provided publicly and also privately through donations, is presented for nationals and for foreigners. The data are obtained from a contingent valuation survey carried out in Venice, the aim of which was to estimate visitors' willingness to donate (WTD) to the Venice flood defence programme. Demand functions are estimated by applying a twostage regression model. The authors show that the majority of visitors are willing to donate. On average, Italians and non-Europeans would donate more than non-Italian Europeans. As expected, these visitor categories have different mean WTD and different behavioural functions which are affected by attitudinal and economic variables. Bequest value is the main donation motive. Those who identify this as a donation motive, on average, state the highest WTD and the highest degree of certainty to donate. This result seems to confirm empirically the validity of the sustainable development principle applied to the management of Venice as a cultural tourist site

    Remote sensing techniques applied to geomorphological mapping of rocky coast: the case study of Gallinara Island (Western Liguria, Italy)

    Get PDF
    Geomorphological survey and mapping of the emerged and submerged coastal areas, particularly addressed to evaluate sea cliff instability within the assessment of coastal hazard and risk mitigation measures, require high resolution and georeferenced spatial data. Remote sensing techniques fully satisfy these needs and allow to obtain all information in a single short-lived survey campaign. An integrated survey by means of laser scanner and multibeam techniques coupled with aerial photos interpretation has been experienced along the rocky coast of the Gallinara Island (Western Liguria, Italy). The small extent of Gallinara, together with its particular meteo-marine climate conditions, makes the island a noteworthy case study. Multibeam and laser scanner technologies allowed to reconstruct the submerged and emerged rocky coast at high resolution. The accuracy of the 3D surface reconstructed by means of laser scanner used in profiler mode was tested and validated, by comparing with the static laser scanner survey method. The resulting data allowed to obtain significant geological and geomorphological information leading to the definition of rocky cliff stability conditions. \ua9 2019, \ua9 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group

    Solutions of elliptic equations with a level surface parallel to the boundary: stability of the radial configuration

    Get PDF
    Positive solutions of homogeneous Dirichlet boundary value problems or initial-value problems for certain elliptic or parabolic equations must be radially symmetric and monotone in the radial direction if just one of their level surfaces is parallel to the boundary of the domain. Here, for the elliptic case, we prove the stability counterpart of that result. In fact, we show that if the solution is almost constant on a surface at a fixed distance from the boundary, then the domain is almost radially symmetric, in the sense that is contained in and contains two concentric balls Bre and Bri, with the difference re 12ri (linearly) controlled by a suitable norm of the deviation of the solution from a constant. The proof relies on and enhances arguments developed in a paper by Aftalion, Busca and Reichel

    Transition rates and nuclear structure changes in mirror nuclei 47Cr and 47V

    Full text link
    Lifetime measurements in the mirror nuclei 47Cr and 47V were performed by means of the Doppler-shift attenuation method using the multidetector array EUROBALL, in conjunction with the ancillary detectors ISIS and the Neutron Wall. The determined transition strengths in the yrast cascades are well described by full pf shell model calculations.Comment: Latex2e, 11 pages, 3 figure
    • …
    corecore