1,203 research outputs found

    An improved geometric inequality via vanishing moments, with applications to singular Liouville equations

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    We consider a class of singular Liouville equations on compact surfaces motivated by the study of Electroweak and Self-Dual Chern-Simons theories, the Gaussian curvature prescription with conical singularities and Onsager's description of turbulence. We analyse the problem of existence variationally, and show how the angular distribution of the conformal volume near the singularities may lead to improvements in the Moser-Trudinger inequality, and in turn to lower bounds on the Euler-Lagrange functional. We then discuss existence and non-existence results.Comment: some references adde

    LANDSAT-4/5 image data quality analysis

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    A LANDSAT Thematic Mapper (TM) quality evaluation study was conducted to identify geometric and radiometric sensor errors in the post-launch environment. The study began with the launch of LANDSAT-4. Several error conditions were found, including band-to-band misregistration and detector-to detector radiometric calibration errors. Similar analysis was made for the LANDSAT-5 Thematic Mapper and compared with results for LANDSAT-4. Remaining band-to-band misregistration was found to be within tolerances and detector-to-detector calibration errors were not severe. More coherent noise signals were observed in TM-5 than in TM-4, although the amplitude was generally less. The scan direction differences observed in TM-4 were still evident in TM-5. The largest effect was in Band 4 where nearly a one digital count difference was observed. Resolution estimation was carried out using roads in TM-5 for the primary focal plane bands rather than field edges as in TM-4. Estimates using roads gave better resolution. Thermal IR band calibration studies were conducted and new nonlinear calibration procedures were defined for TM-5. The overall conclusion is that there are no first order errors in TM-5 and any remaining problems are second or third order

    Semilinear equations with exponential nonlinearity and measure data

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    We study the existence and non-existence of solutions of the problem [GRAPHICS] where Omega is a bounded domain in R-N, N >=, 3, and it is a Radon measure. We prove that if it 4 pi HN-2, then (0.1) has a unique solution. We also show that the constant 4 pi in this condition cannot be improved. (c) 2005 Elsevier SAS. All rights reserved

    Existence of Multistring Solutions of the Self-Gravitating Massive WW-Boson

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    We consider a semilinear elliptic system which include the model system of the WW-strings in the cosmology as a special case. We prove existence of multi-string solutions and obtain precise asymptotic decay estimates near infinity for the solutions. As a special case of this result we solve an open problem posed in \cite{yan}Comment: 12 page

    Classification and nondegeneracy of SU(n+1)SU(n+1) Toda system with singular sources

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    We consider the following Toda system \Delta u_i + \D \sum_{j = 1}^n a_{ij}e^{u_j} = 4\pi\gamma_{i}\delta_{0} \text{in}\mathbb R^2, \int_{\mathbb R^2}e^{u_i} dx -1,, \delta_0isDiracmeasureat0,andthecoefficients is Dirac measure at 0, and the coefficients a_{ij}formthestandardtridiagonalCartanmatrix.Inthispaper,(i)wecompletelyclassifythesolutionsandobtainthequantizationresult: form the standard tri-diagonal Cartan matrix. In this paper, (i) we completely classify the solutions and obtain the quantization result: j=1naijR2eujdx=4π(2+γi+γn+1i),      1in.\sum_{j=1}^n a_{ij}\int_{\R^2}e^{u_j} dx = 4\pi (2+\gamma_i+\gamma_{n+1-i}), \;\;\forall\; 1\leq i \leq n.ThisgeneralizestheclassificationresultbyJostandWangfor This generalizes the classification result by Jost and Wang for \gamma_i=0,, \forall \;1\leq i\leq n.(ii)Weprovethatif. (ii) We prove that if \gamma_i+\gamma_{i+1}+...+\gamma_j \notin \mathbb Zforall for all 1\leq i\leq j\leq n,thenanysolution, then any solution u_i$ is \textit{radially symmetric} w.r.t. 0. (iii) We prove that the linearized equation at any solution is \textit{non-degenerate}. These are fundamental results in order to understand the bubbling behavior of the Toda system.Comment: 28 page

    Conserving plant diversity in Europe: outcomes, criticisms and perspectives of the Habitats Directive application in Italy

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    Habitat Directive is the core strategy of nature conservation in Europe aiming at halting biodiversity loss. In this study the results of the third Italian assessment regarding the conservation status (CS) of plants listed in the Habitat Directive (Flora of community interest—FCI) was presented. Data was collected from several sources related to plant distribution, population data, habitats and pressures. Following the official European procedure, all parameters were evaluated and combined to give the CS of each taxon in each biogeographical region of presence. A comparison between the recent Italian IUCN and Reporting assessments was performed in order to evaluate the consistency between these two assessments. The official EU checklist comprises 113 Italian plant taxa, 107 of which were examined in this study. Our results showed a critical situation with only 34% of favourable CS, while 50% were unfavourable (40% inadequate plus 10% bad) and 16% unknown, in particular in the Mediterranean bioregion, where the unfavourable assessments reach the 65%. The results of the Report were consistent with those of the IUCN assessment, in which 41.9% of plants were threatened with extinction. This report highlighted some benefits and criticisms at national level, but it may have a wider significance. Although a general advance of knowledge, a great effort is needed to reach the Habitats Directive goals. Despite the limited resources, monitoring activities needs to be improved in order to close information gaps for several plants. A positive outcome was the development of a specific national project funded by the Italian Ministry of Environment, with the ambitious target to set future monitoring activities for FCI and optimize monitoring efforts

    RF MEMS ohmic switches for matrix configurations

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    Two different topologies of radio frequency micro-electro-mechanical system (RF MEMS) series ohmic switches (cantilever and clamped–clamped beams) in coplanar waveguide (CPW) configuration have been characterized by means of DC, environmental, and RF measurements. In particular, on-wafer checks have been followed by RF test after vibration, thermal shocks, and temperature cycles. The devices have been manufactured on high resistivity silicon substrates, as building blocks to be implemented in different single-pole 4-throw (SP4 T), double-pole double-throw (DPDT) configurations, and then integrated in Low Temperature Co-fired Ceramics (LTCC) technology for the realization of large-order Clos 3D networks

    Hospital Organization and Importance of an Interventional Radiology Inpatient Admitting Service:Italian Single-Center 3-year Experience

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    In June 2005 a Complex Operating Unit of Interventional Radiology (COUIR), consisting of an outpatient visit service, an inpatient admitting service with four beds, and a day-hospital service with four beds was installed at our department. Between June 2005 and May 2008, 1772 and 861 well-screened elective patients were admitted to the inpatient ward of the COUIR and to the Internal Medicine Unit (IMU) or Surgery Unit (SU) of our hospital, respectively, and treated with IR procedures. For elective patients admitted to the COUIR’s inpatient ward, hospital stays were significantly shorter and differences between reimbursements and costs were significantly higher for almost all IR procedures compared to those for patients admitted to the IMU and SU (Student’s t-test for unpaired data, p\0.05). The results of the 3-year activity show that the activation of a COUIR with an inpatient admitting service, and the better organization of the patient pathway that came with it, evidenced more efficient use of resources, with the possibility for the hospital to save money and obtain positive margins (differences between reimbursements and costs). During 3 years of activity, the inpatient admitting service of our COUIR yielded a positive difference between reimbursements and effective costs of €1,009,095.35. The creation of an inpatient IR service and the admission of well-screened elective patients allowed short hospitalization times, reduction of waiting lists, and a positive economic outcome. Keywords Inpatients Hospitalization Costs Reimbursement

    Primary-school class composition and the development of social capital

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    We study the development of social capital through adult civic engagement, in relation to social capital exposure having occurred during childhood based on experiences outside the family at primary school. We assume that the types of classmates in attendance at a child's school would have influenced her/his social capital. To identify the types of classmates, we take advantage of the heterogeneity in the ability levels of British primary-school classes during the 1960s. At that time, some schools were practicing a method of streaming, whereas others were not. Using British National Child Development data, we construct a single score of civic engagement and evaluate the effect on adult civic engagement of attending homogeneous-ability classes versus nonhomogeneous-ability classes and being in high-, average- or low-ability classes when enrolled in streamed schools. Our results show that children who were grouped in homogeneous-ability classes developed a lower interest in civic engagement than their peers who attended mixed-ability classes (nonstreamed schools). Moreover, among children who attended streamed schools, a lower attitude toward civic engagement was observed among low-ability students. Thus, streaming appears to be detrimental to social capital development, especially for low-ability individuals
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