423 research outputs found

    On the asymptotic behaviour of solutions to the fractional porous medium equation with variable density

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    We are concerned with the long time behaviour of solutions to the fractional porous medium equation with a variable spatial density. We prove that if the density decays slowly at infinity, then the solution approaches the Barenblatt-type solution of a proper singular fractional problem. If, on the contrary, the density decays rapidly at infinity, we show that the minimal solution multiplied by a suitable power of the time variable converges to the minimal solution of a certain fractional sublinear elliptic equation.Comment: To appear in DCDS-

    The Kuznets curve of the rich

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    A long-standing interest in the relationship between inequality and sustainable growth continues to fascinate economists among other social scientists. It must be noted, however, that most empirical efforts have focussed on the income inequality–growth nexus, while studies on wealth inequality are much scarcer. This study attempts to fill such a gap in the literature by assessing the correspondence between the top 1 percent's wealth share and economic growth. Employing time series cointegration techniques, we study the experience of France and the United States from 1950 to 2014. Our estimates suggest that the output growth rate is an inverted-U-shaped function of the wealth share of the top 1 percent. The estimated relationship is robust to variations in control variables and estimation methods. We compute the local optimal wealth share, understood as the share of wealth compatible with the maximum growth rate, and show that France is growing close to its long-run potential, while the United States is significantly below its

    SlicerAstro: a 3-D interactive visual analytics tool for HI data

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    SKA precursors are capable of detecting hundreds of galaxies in HI in a single 12 hours pointing. In deeper surveys one will probe more easily faint HI structures, typically located in the vicinity of galaxies, such as tails, filaments, and extraplanar gas. The importance of interactive visualization has proven to be fundamental for the exploration of such data as it helps users to receive immediate feedback when manipulating the data. We have developed SlicerAstro, a 3-D interactive viewer with new analysis capabilities, based on traditional 2-D input/output hardware. These capabilities enhance the data inspection, allowing faster analysis of complex sources than with traditional tools. SlicerAstro is an open-source extension of 3DSlicer, a multi-platform open source software package for visualization and medical image processing. We demonstrate the capabilities of the current stable binary release of SlicerAstro, which offers the following features: i) handling of FITS files and astronomical coordinate systems; ii) coupled 2-D/3-D visualization; iii) interactive filtering; iv) interactive 3-D masking; v) and interactive 3-D modeling. In addition, SlicerAstro has been designed with a strong, stable and modular C++ core, and its classes are also accessible via Python scripting, allowing great flexibility for user-customized visualization and analysis tasks.Comment: 18 pages, 11 figures, Accepted by Astronomy and Computing. SlicerAstro link: https://github.com/Punzo/SlicerAstro/wiki#get-slicerastr

    Nuove specie minerali al Somma-Vesuvio: wulfenite

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    To the 247 species, of which 20 are doubtful, occurring at the Somma-Vesuvius volcanic complex, after the recent updating of the fluoro-edenite (despite the collecting ban) it has to be added the identification of a new common species, never occurred before. A sample belonging to Luigi Chiappino, found in 1989 at San Vito quarry, Ercolano, Napoli, was analyzed through SEM-EDX and the analysis identified the wulfenite on massive galena, as millimetrical, bipyramidal crystals, resinous, of yellow-orange colour, associated with calcite, cerussite and sphalerite

    Narrative review of cardiac computed tomography perfusion: insights into static rest perfusion

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    Cardiac or left ventricular perfusion performed with cardiac computed tomography (CCT) is a developing method that may have the potential to complete in a very straight forward way the assessment of ischemic heart disease by means of CT. Myocardial CT perfusion (CTP) can be achieved with a single static scan during the first-pass of the iodinate contrast agent, with the monoenergetic or dual-energy acquisition, or as a dynamic, time-resolved scan during stress by using coronary vasodilator agents. Several methods can be performed, and we focused on static perfusion. CTP may serve as a useful adjunct to coronary CT angiography (CTA) to improve specificity of detecting myocardial ischemia. Technological advances will reduce the radiation dose of myocardial CTP, such as low tube voltage imaging or new reconstruction algorithms, making it a more viable clinical option. The advantages of static first-pass non-stress perfusion are several; the main one is that it can be done to each and every patient who undergoes CCT for the assessment of coronary artery tree. Future advances in CTP will likely improve the diagnostic accuracy of CTP + CTA, and will better estimate the severity of ischemia Therefore, it is simple and comprehensive. However, it has several limitations. In this review we will discuss the technique with its advantages and limitations

    Coronary atherosclerosis as the main endpoint of non-invasive imaging in cardiology: A narrative review

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    The change of paradigm determined by the introduction of cardiac computed tomography (CCT) in the field of cardiovascular medicine has allowed new evidence to emerge. These evidences point towards a major role, probably the most important one in terms of prognostic impact, in the detection, characterization and quantification of atherosclerosis as the main driver and endpoint for the management of coronary artery disease (CAD). Extensive literature has been published in the last decade with large numbers and patients’ populations, investigating several aspects and correlations between atherosclerotic plaque features and risk factors; also, the relationship between plaque features, both with qualitative and quantitative approaches, and cardiovascular events has been investigated. More recent studies have also pointed out the relationship between the knowledge and classification of sub-clinical atherosclerosis and the induced modification of medical therapy (both aggressiveness and compliance) that is most likely able to increase the effect of anti-atherosclerotic drugs, hence significantly improving prognosis. Non-invasive assessment of CAD by means of CCT is becoming the primary tool for management and also the most important parameter for the comprehension of natural history of CAD and how the therapies we adopt are affecting plaque burden as a whole. In this review we will address the modern concepts of CAD driven understanding and management of cardiovascular disease

    Insight from imaging on plaque vulnerability: similarities and differences between coronary and carotid arteries—implications for systemic therapies

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    Nowadays it is widely accepted that the rupture of the atherosclerotic plaque in coronary and carotid arteries plays a fundamental role in the development of acute myocardial infarctions or cerebrovascular events. In recent years, imaging techniques have explored, with a new level of detail, the atherosclerotic disease generating new evidences that some plaque characteristics are significantly associated to the risk of rupture and subsequent thrombosis or embolization. Moreover, the recent evidence of the anti-atherosclerotic effects determined by lipid-lowering and anti-inflammatory therapies poses a challenge for the choice of therapeutic approaches (best/optimal medical therapy vs. revascularization), maximized by the evidence that coronary and carotid atherosclerosis share common patterns but also differ regarding some important features. In this Review, we discuss the similarities and differences between coronary and carotid artery vulnerable plaque from the imaging point of view and the potential implications for systemic therapies according to the emerging evidence

    Comparison of hybridization-based and sequencing-based gene expression technologies on biological replicates

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    <p>Abstract</p> <p>Background</p> <p>High-throughput systems for gene expression profiling have been developed and have matured rapidly through the past decade. Broadly, these can be divided into two categories: hybridization-based and sequencing-based approaches. With data from different technologies being accumulated, concerns and challenges are raised about the level of agreement across technologies. As part of an ongoing large-scale cross-platform data comparison framework, we report here a comparison based on identical samples between one-dye DNA microarray platforms and MPSS (Massively Parallel Signature Sequencing).</p> <p>Results</p> <p>The DNA microarray platforms generally provided highly correlated data, while moderate correlations between microarrays and MPSS were obtained. Disagreements between the two types of technologies can be attributed to limitations inherent to both technologies. The variation found between pooled biological replicates underlines the importance of exercising caution in identification of differential expression, especially for the purposes of biomarker discovery.</p> <p>Conclusion</p> <p>Based on different principles, hybridization-based and sequencing-based technologies should be considered complementary to each other, rather than competitive alternatives for measuring gene expression, and currently, both are important tools for transcriptome profiling.</p
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