285 research outputs found

    Analyzing Intra-Distribution Dynamics: A Reappraisal

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    In this paper we suggest an alternative estimator and an alternative graphical analysis, both developed by Hyndman et al. (1996), to describe the law of motion of cross-sectional distributions of per-capita income and its components in Europe. This estimator has better properties than the kernel density estimator generally used in the literature on intra-distribution dynamics (cf. Quah, 1997). By using the new estimator, we obtain evidence of a very strong persistent behavior of the regions considered in the study, that is poor regions tend to remain poorer and rich regions tend to remain richer. These results are also in line with the most recent literature available on the distribution dynamic approach to regional convergence (Pittau and Zelli, 2006).

    Synthesis and Characterization of Bi2S3 Colloidal Nanoparticles for Photovoltaic Applications

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    Global energy consumption is expected to increase significantly together with the greenhouse gas emissions and the problem of fossil fuels exhaustion. Solar energy, as an alternative and renewable form of energy, has gained pop- ularity as possible solution for all these problems. Lots of materials have been studied to implement the energy conversion efficiency of the so-called third generation solar cells. These devices could be a cheaper alternatives to the silicon-based ones. Unfortunately, they are often characterized by short life- time or health hazardous materials. Bismuth sulfide(Bi2S3) is a promising n-type semiconductor for solar energy conversion.In this work,the properties of the compound will be discussed,as well as its potential for applications in solar energy technology.Wehave explored the colloidal synthesis of Bi2S3 nanocrystals,with the aim of employing them in the fabrication of solution- processable solar cells and to replace toxic heavy metals chalcogenides likePbS or CdS,that are currently employed in such devices. We compare different methods to obtain Bi2S3 colloidal quantum dots, including the useof environmentally benign reactants, through horganometallic synthesis. Surfactant-assisted colloidal synthesis(SACS) methods were used to synthesize Bi2S3 nanoparticles with different size and shape.These methods have been employed changing systematically several parameters such as temperature and timeofsynthesis, concentration ofchemical reagents and sulfur precursors. Morphological characteristics and optical properties of all the synthesized nanoparticles have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), UV-Vis and photoluminescence (PL) spectroscopy. After the characterization of electrical properties of bismuth sulfide sam- ples together with the preliminary attempts to find the most advantageous methods for the production of homogeneous film on conductive supports, asample was chosen like standard and it was employed in building of various prototype of third generation solution processed solar cells. Dip and spin coat- ing techniques were employed to produce homogeneous film of nanoparticleson conductive support, also in combination with organic polymer such P3HT, Pedot:PSS and Spiro-OMeTAD. The resulting solar cells were tested for power conversion efficiency (PCE). Synthesis and characterizations have been carried out in Dipartimento di Scienze Chimiche e Geologiche, Università degli Studi di Cagliari, under the supervision of Prof. Anna Musinu and Prof. Carla Cannas. Optoelectronic characterizations and solar cells manufacturing have been carried out in Di- partimento di Fisica, Università degli Studi di Cagliari, under the supervision of Prof. Michele Saba, Prof. Andrea Mura and Prof. Giovanni Bongiovanni

    Dieci partigiani ossesi nella Resistenza italiana

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    La ricostruzione delle vicende biografiche dei dieci partigiani originari di Ossi finora identificati, riproponendo implicitamente il tema del rapporto fra vicissitudini individuali ed eventi storici, si inserisce nel più ampio contesto del contributo della ricerca locale e settoriale alla storiografia della Resistenza. In tal senso l’articolo, sintesi introduttiva di una monografia in corso di pubblicazione, si propone come ulteriore tassello nel quadro degli studi tuttora in corso sul contributo dei sardi alla guerra di Liberazione

    Il cgml: una soluzione basata su xml per la rappresentazione di mappe vettoriali su dispositivi mobili

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    L’evoluzione tecnologica dei dispositivi mobili, in termini di potenza di calcolo, capacità di visualizzazione e memorizzazione, e il proliferare di sistemi di connessione a banda larga su rete locale wireless (WiFi) e cellulare (UMTS), permette la gestione di dati complessi quali le mappe vettoriali e l’accesso ai Location Based Service (LBS) per mezzo di un telefono cellulare o un palmare. L’uso di linguaggi XML nel settore dei LBS condiziona la struttura delle funzionalità e dei dati ma garantisce l’interoperabilità dei servizi. Un esempio è il linguaggio GML (Geographic Markup Language) standard de facto nello scambio dei dati tra sistemi GIS e nella rappresentazione dell’informazione geografica. Il GML non è orientato alla rappresentazione di mappe vettoriali, è quindi necessario trasformarlo in un altro linguaggio XML, ad esempio il linguaggio grafico SVG (Scalable Vector Graphics). Per evitare la separazione tra il dato geografico (GML) e la sua visualizzazione (Mobile SVG) ma usando comunque le mappe vettoriali su dispositivi mobili, abbiamo definito il cGML (compact Geographic Markup Language). La rappresentazione di un dato tramite cGML è una mappa vettoriale e come tale può essere utilizzata nella presentazione grafica, ma allo stesso momento è anche un contenitore di insiemi di dati geo-riferiti, omogenei per semantica, utilizzabili in elaborazioni locali sul dispositivo mobile.Enhanced mobile device performances, in terms of CPU power, memory capacity, display capabilities and adoption of wideband connectivity based on local wireless (WiFi) and cellular (UMTS) networks, bring interactive mapping and access to Location Based Services (LBS) to mobile phones and PDAs. The use of XML language in the LBS influences data structure, functionalities and performances; although it could be time and memory expensive, it guarantees service interoperability. The GML language (Geographic Markup Language) is "de facto" standard in data exchanging between Geographic Information Systems. The GML has not been designed to represent vector map: it has to be transformed into another XML language, for example the graphical-oriented XML language Mobile SVG. To avoid the separation between the geographic data (GML) and its visualization (Mobile SVG), keeping vector mapping on mobile devices, we have designed the cGML (compact Geographic Markup Language). The data encoded using cGML is a vector map, so that it can be used in the graphic representation, but at the same time it is a container of geographical related data set, homogenous for semantic and usable in local processing on the mobile device

    Compact gml: merging mobile computing and mobile cartography

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    The use of portable devices is moving from "Wireless Applications", typically implemented as browsing-on-the-road, to "Mobile Computing", which aims to exploit increasing processing power of consumer devices. As users get connected with smartphones and PDAs, they look for geographic information and location-aware services. While browser-based approaches have been explored (using static images or graphics formats such as Mobile SVG), a data model tailored for local computation on mobile devices is still missing. This paper presents the Compact Geographic Markup Language (cGML) that enables design and development of specific purpose GIS applications for portable consumer devices where a cGML document can be used as a spatial query result as well

    The cgml: a xml language for mobile cartography

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    Increasing processing power and storage capabilities encourage systematic adoption of high-end mobile devices, such as programmable cellular phones and wireless-enabled PDA to implement new exciting applications. The performances of modern mobile devices are bringing innovative scenarios, based on position awareness and ambient intelligence paradigms. The market is moving from old 'Wireless Applications' approach to Mobile Computing, which aims to exploit mobile host capabilities. This paper presents the compact Geographic Markup Language (cGML), an XML-based language defined to enable design and development of LBS applications specific for mobile devices, and an example of client-server architecture using it

    Distributed hydrologic modeling of a sparsely monitored basin in Sardinia, Italy, through hydrometeorological downscaling

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    The water resources and hydrologic extremes in Mediterranean basins are heavily influenced by climate variability. Modeling these watersheds is difficult due to the complex nature of the hydrologic response as well as the sparseness of hydrometeorological observations. In this work, we present a strategy to calibrate a distributed hydrologic model, known as TIN-based Real-time Integrated Basin Simulator (tRIBS), in the Rio Mannu basin (RMB), a medium-sized watershed (472.5 km2) located in an agricultural area in Sardinia, Italy. In the RMB, precipitation, streamflow and meteorological data were collected within different historical periods and at diverse temporal resolutions. We designed two statistical tools for downscaling precipitation and potential evapotranspiration data to create the hourly, high-resolution forcing for the hydrologic model from daily records. Despite the presence of several sources of uncertainty in the observations and model parameterization, the use of the disaggregated forcing led to good calibration and validation performances for the tRIBS model, when daily discharge observations were available. The methodology proposed here can be also used to disaggregate outputs of climate models and conduct high-resolution hydrologic simulations with the goal of quantifying the impacts of climate change on water resources and the frequency of hydrologic extremes within medium-sized basins

    Haplotype affinities resolve a major component of goat (<i>Capra hircus</i>) MtDNA D-loop diversity and reveal specific features of the Sardinian stock

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    Goat mtDNA haplogroup A is a poorly resolved lineage absorbing most of the overall diversity and is found in locations as distant as Eastern Asia and Southern Africa. Its phylogenetic dissection would cast light on an important portion of the spread of goat breeding. The aims of this work were 1) to provide an operational definition of meaningful mtDNA units within haplogroup A, 2) to investigate the mechanisms underlying the maintenance of diversity by considering the modes of selection operated by breeders and 3) to identify the peculiarities of Sardinian mtDNA types. We sequenced the mtDNA D-loop in a large sample of animals (1,591) which represents a non-trivial quota of the entire goat population of Sardinia. We found that Sardinia mirrors a large quota of mtDNA diversity of Western Eurasia in the number of variable sites, their mutational pattern and allele frequency. By using Bayesian analysis, a distance-based tree and a network analysis, we recognized demographically coherent groups of sequences identified by particular subsets of the variable positions. The results showed that this assignment system could be reproduced in other studies, capturing the greatest part of haplotype diversity. We identified haplotype groups overrepresented in Sardinian goats as a result of founder effects. We found that breeders maintain diversity of matrilines most likely through equalization of the reproductive potential. Moreover, the relevant amount of inter-farm mtDNA diversity found does not increase proportionally with distance. Our results illustrate the effects of breeding practices on the composition of maternal gene pool and identify mtDNA types that may be considered in projects aimed at retrieving the maternal component of the oldest breeds of Sardinia.</br

    Chitosan-Based Nanoparticles Containing Cherry Extract from Prunus avium L. to Improve the Resistance of Endothelial Cells to Oxidative Stress

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    Cherries are known for their nutraceutical properties, in particular for their antioxidant ability due to their polyphenol content, which causes a reduction of cardiovascular disease (CVD) risk factors. However, once ingested these molecules are degraded in the Gastrointestinal (GI) tract before reaching the blood, which is the action site. The object of the present work is to evaluate the ability of cherry extract (CE), encapsulated in nanoparticles (NPs) based on different chitosan (Ch) derivatives, to promote a protective effect of human umbilical vein endothelial cells (HUVECs) involved in vascular dysfunction against oxidative stress. CE-loaded NPs based on quaternary ammonium chitosan (NP1) and an S-protected thiolated derivative thereof (NP2) were prepared. The mean particle size (NP1 344.9 ± 17.8, NP2 339.9 ± 68.2 nm), the polydispersity index, the encapsulation efficiency (NP1 78.4 ± 4.5, NP2 79.8 ± 0.6%), and the zeta potential (NP1 14.8 ± 0.3, NP2 15.8 ± 0.5 mV) did not appear to be significantly different. Both NP types improved the CE apparent permeation parameters with respect to the control. Conversely, CE-loaded NP2 protected HUVECs from oxidative stress and reduced reactive oxygen species (ROS) production more than CE-loaded NP1 and free CE. In addition to promoting HUVEC resistance, NP2 could be a useful tool to overcome the problem of cherry seasonality

    What unrelated hematopoietic stem cell transplantation in thalassemia taught us about transplant immunogenetics

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    Although the past few decades have shown an improvement in the survival and complication-free survival rates in patients with beta-thalassemia major and gene therapy is already at an advanced stage of experimentation, hematopoietic stem cell transplantation (HSCT) continues to be the only effective and realistic approach to the cure of this chronic nonmalignant disease. Historically, human leukocyte antigen (HLA)-matched siblings have been the preferred source of donor cells owing to superior outcomes compared with HSCT from other sources. Nowadays, the availability of an international network of voluntary stem cell donor registries and cord blood banks has significantly increased the odds of finding a suitable HLA matched donor. Stringent immunogenetic criteria for donor selection have made it possible to achieve overall survival (OS) and thalassemia-free survival (TFS) rates comparable to those of sibling transplants. However, acute and chronic graft-versus-host disease (GVHD) remains the most important complication in unrelated HSCT in thalassemia, leading to significant rates of morbidity and mortality for a chronic non-malignant disease. A careful immunogenetic assessment of donors and recipients makes it possible to individualize appropriate strategies for its prevention and management. This review provides an overview of recent insights about immunogenetic factors involved in GVHD, which seem to have a potential role in the outcome of transplantation for thalassemia
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