864 research outputs found

    Snow cover monitoring by machine processing of multitemporal LANDSAT MSS data

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    LANDSAT frames were geometrically corrected and data sets from six different dates were overlaid to produce a 24 channel (six dates and four wavelength bands) data tape. Changes in the extent of the snowpack could be accurately and easily determined using a change detection technique on data which had previously been classified by the LARSYS software system. A second phase of the analysis involved determination of the relationship between spatial resolution or data sampling frequency and accuracy of measuring the area of the snowpack

    A nonparametric multidimensional latent class IRT model in a Bayesian framework

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    We propose a nonparametric Item Response Theory model for dichotomously scored items in a Bayesian framework. Partitions of the items are defined on the basis of inequality constraints among the latent class success probabilities. A Reversible Jump type algorithm is described for sampling from the posterior distribution. A consequence is the possibility to make inference on the number of dimensions (i.e., number of groups of items measuring the same latent trait) and to cluster items when unidimensionality is violated

    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

    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

    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

    Climate-induced conservation risks of historic reinforced concrete buildings: Preliminary results from literature review

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    Environmental conditions can favour different kinds of deterioration in historic reinforced concrete structures. This preliminary results from literature review are focused on the climate-induced risks affecting reinforced concrete buildings with respect to mechanical, chemical, and biological deterioration. To this purpose, a three-step process defined by the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow diagram, was used leading to the inclusion of 45 documents identified via the search engines Scopus and Web of Science. The outcomes highlight that chemical and mechanical decays are the most investigated ones, being mainly triggered by salt weathering and freezing-thawing cycles. It was found that experimental and theoretical approaches are often coupled to estimate climate-induced deterioration mechanisms, also considering environmental parameters. Finally, the literature search provides some milestones which can be used to evaluate gaps and research needs in the field of climate-induced conservative risks affecting reinforced concrete structures

    MYCN Impact on High-Risk Neuroblastoma: From Diagnosis and Prognosis to Targeted Treatment

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    Simple Summary Neuroblastoma is one of the most diffuse and the deadliest cancer in children. While many advances have been made in the last few decades to improve patients' outcome, high-risk neuroblastoma (HR-NB) still shows a very aggressive pattern of development and poor prognosis, with only a 50% chance of 5-year survival. Moreover, while many factors contribute to defining the high-risk condition, MYCN status is well established as the major element in pathology disclosure. The aim of this review is to describe the current knowledge in the diagnosis, prognosis and therapeutic approaches of HR-NB, particularly in relation to MYCN. The review highlights how MYCN influences the HR-NB scenario and the new therapeutic approaches that are currently proposed to target it, in consideration of MYCN as a highly relevant target for HR-NB patient management. Among childhood cancers, neuroblastoma is the most diffuse solid tumor and the deadliest in children. While to date, the pathology has become progressively manageable with a significant increase in 5-year survival for its less aggressive form, high-risk neuroblastoma (HR-NB) remains a major issue with poor outcome and little survivability of patients. The staging system has also been improved to better fit patient needs and to administer therapies in a more focused manner in consideration of pathology features. New and improved therapies have been developed; nevertheless, low efficacy and high toxicity remain a staple feature of current high-risk neuroblastoma treatment. For this reason, more specific procedures are required, and new therapeutic targets are also needed for a precise medicine approach. In this scenario, MYCN is certainly one of the most interesting targets. Indeed, MYCN is one of the most relevant hallmarks of HR-NB, and many studies has been carried out in recent years to discover potent and specific inhibitors to block its activities and any related oncogenic function. N-Myc protein has been considered an undruggable target for a long time. Thus, many new indirect and direct approaches have been discovered and preclinically evaluated for the interaction with MYCN and its pathways; a few of the most promising approaches are nearing clinical application for the investigation in HR-NB

    FlorItaly-the portal to the flora of Italy

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    Digital data concerning the flora of Italy are largely fragmented among different resources hosted on different platforms, and often with different data standards, which are neither connected by a common access point, nor by web services, thus constituting a relevant obstacle to data access and usage. Taxonomic incongruences add a further complication. This paper describes "FlorItaly", an online information system which allows to access and query updated information on the checklist of the flora of Italy, aiming at becoming an aggregator for Italian botanical resources. "FlorItaly" was developed in a collaborative effort by more than 50 taxonomists, with the support of the Italian Botanical Society, and of Project "Dryades" (University of Trieste), to provide a better and reliable organization of botanical knowledge in Italy, as well as a relevant simplification for data retrieval, and a further stimulus towards a more collaborative approach in botanical research
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