937 research outputs found

    On the Chinese Exchange Rate Regime: an Attempt to Flexibility during 2015

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    This study will demonstrate, through an econometric and asset allocation approach, if and how the Chinese exchange rate regime was changing during 2015. Particularly, China to improve its exchange rate formation system implemented, during July and August 2015, three depreciation as a step toward a market-oriented exchange rate. This situation, along with the new right of the RMB to be an international currency in SDR should generate a loss of weight about the USD in the Chinese basket peg. For this reason, moving from Frankel-Wei’s basic econometric model - but with some appropriate changes - our objective is to verify if the Chinese monetary policy about the exchange rate has affected the inner balance of the Chinese basket-peg leading it towards a flexible exchange rate regime

    Small Extracellular Vesicles from Human Amniotic Fluid Samples as Promising Theranostics

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    Since the first evidence that stem cells can provide pro-resolving effects via paracrine secretion of soluble factors, growing interest has been addressed to define the most ideal cell source for clinical translation. Leftover or clinical waste samples of human amniotic fluid obtained following prenatal screening, clinical intervention, or during scheduled caesarean section (C-section) delivery at term have been recently considered an appealing source of mesenchymal progenitors with peculiar regenerative capacity. Human amniotic fluid stem cells (hAFSC) have been demonstrated to support tissue recovery in several preclinical models of disease by exerting paracrine proliferative, anti-inflammatory and regenerative influence. Small extracellular vesicles (EVs) concentrated from the hAFSC secretome (the total soluble trophic factors secreted in the cell-conditioned medium, hAFSC-CM) recapitulate most of the beneficial cell effects. Independent studies in preclinical models of either adult disorders or severe diseases in newborns have suggested a regenerative role of hAFSC-EVs. EVs can be eventually concentrated from amniotic fluid (hAF) to offer useful prenatal information, as recently suggested. In this review, we focus on the most significant aspects of EVs obtained from either hAFSC and hAF and consider the current challenges for their clinical translation, including isolation, characterization and quantification methods

    Band Gap Modeling of Different Ternary and Quaternary Alumina Garnet Phases Y3(AlXGa1-X)5O12 (YAGG) and Lu3(AlXGa1-X)5O12 (LuAGG). A Semiempirical Approach

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    A further generalization to quaternary oxide systems of the modeling equation of optical band gap values, based on the semiempirical correlation between the differences in the electronegativity of oxygen and the average cationic electronegativity, proposed some years ago, has been carried out by expanding the approach recently employed for ternary mixed oxides. The choice of oxide polymorphs and their influence on the fitting procedure of an experimental data set is evidenced by a detailed discussion of the fitting process of the literature's experimental band gap data pertaining two quaternary oxide systems of the garnet family, namely, Y3(AlxGa1-x)5O12 (YAGG) and Lu3(AlxGa1-x)5O12 (LuAGG), playing an important role in several engineering applications. The two investigated systems, moreover, span a quite large range of band gap energy values (from similar to 5.5 to similar to 7.5 eV), as a function of the Al/Ga ratio, allowing a rigorous test of the proposed modeling equation. Based on the wide existing literature on the presence of excitonic effects in the investigated systems some empirical correlations between an optical gap and a band gap in the presence of excitonic effects are suggested, too, which could provide some rationale to overcome the discrepancies frequently encountered in comparing band gap values reported in the literature for the same materials. The results of this work confirm the ability of this semiempirical approach in providing good agreement between experimental and theoretical band gap values also for very complex systems, where more sophisticated density functional theory-based methods face some difficulties in predicting the correct values

    A Generalized Semiempirical Approach to the Modeling of the Optical Band Gap of Ternary Al-(Ga, Nb, Ta, W) Oxides Containing Different Alumina Polymorphs

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    A generalization of the modeling equation of optical band gap values for ternary oxides, as a function of cationic ratio composition, is carried out based on the semiempirical correlation between the differences in the electronegativity of oxygen and the average cationic electronegativity proposed some years ago. In this work, a novel approach is suggested to account for the differences in the band gap values of the different polymorphs of binary oxides as well as for ternary oxides existing in different crystalline structures. A preliminary test on the validity of the proposed modeling equations has been carried out by using the numerous experimental data pertaining to alumina and gallia polymorphs as well as the crystalline ternary Ga(1-x)AlxO3 polymorphs (α-Ga(1-x)AlxO3 and β-Ga(1-x)AlxO3) covering a large range of optical band gap values (4.50-8.50 eV). To make a more rigorous test of the modeling equation, we extended our investigation to amorphous ternary oxides anodically formed on Al-d-metal alloys (Al-Nb, Al-Ta, and Al-W) covering a large range of d-metal composition (xd-metal ≥ 0.2). In the last case, the novel approach allows one to overcome some difficulties experienced in fitting the optical band gap dependence from the Al-d-metal mixed anodic oxide composition as well as to provide a rationale for the departure, at the lowest d-metal content (xd-metal < 0.2), from the behavior observed for anodic films containing higher d-metal content

    A geostatistical fusion approach using UAV data for probabilistic estimation of Xylella fastidiosa subsp. pauca infection in olive trees

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    Xylella fastidiosa is one of the most destructive plant pathogenic bacteria worldwide, affecting more than 500 plant species. In Apulia region (southeastern Italy), X. fastidiosa subsp. pauca (Xfp) is responsible for a severe disease, the olive quick decline syndrome (OQDS), spreading epidemically and with dramatic impact on the agriculture, the landscape, the tourism, and the cultural heritage of this region. An early detection of the infected plants would hinder the rapid spread of the disease. The main objective of this paper was to define a geostatistical approach of data fusion, which combines remote (radiometric), and proximal (geophysical) sensor data and visual inspections with plant diagnostic tests, to provide probabilistic maps of Xfp infection risk. The study site was an olive grove located at Oria (province of Brindisi, Italy), where at the time of monitoring (September 2017) only few plants showed initial symptoms of the disease. The measurements included: 1) acquisitions of reflected electromagnetic radiation with UAV (Unmanned Aerial Vehicle) equipped with a multi-spectral camera; 2) geophysical surveys on the trunks of 49 plants with Ground Penetrating Radar (GPR); 3) disease severity rating, by visual inspection of the proportion of canopy with symptoms; 4) qPCR (real time-quantitative Polymerase Chain Reaction) data from tests on 61 plants. The data were submitted to a set of processing techniques to define a “data fusion” procedure, based on non-parametric multivariate geostatistics. The approach allowed marking those areas where the risk of infection was higher, and identifying the possible infection entry routes into the field. The probability map of infection risk could be used as an effective tool for a preventive action and for a better organization of the monitoring plans

    Case report: Fulminant pneumococcal sepsis in an unvaccinated asplenic patient in Italy

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    We report a fatal case of overwhelming pneumococcal infection in an asplenic young adult not vaccinated against Streptococcus pneumoniae (S. pneumoniae). Post-mortem microbiological investigations revealed the presence of S. pneumoniae in blood samples and lungs. Serotyping by molecular methods identified the presence of a 6C serotype not comprised in the current 23-valent pneumococcal vaccine, highlighting that a risk of fatal infections may persist even in vaccinated splenectomised individuals

    HIV awareness: A kap study among students in Italy reveals that preventive campaigns still represent a public health priority

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    Background. Improving knowledge about HIV/AIDS among young people is crucial for preventing new infections. The aim of the study was to investigate knowledge, attitudes and practices regarding HIV infection among students attending university courses related to the healthcare professions, in order to better target future preventive and informative HIV campaigns tailored for young people. Study Design. A knowledge, attitude and practices study was conducted among university students attending the following university courses in Bari (Southern Italy): Medicine and Surgery (MS), Dentistry and Dental Prostheses, Health Assistance, Motor Activities and Sports Sciences, Sciences and Technology of Herbal and Health Products, Nursing, Biomedical Laboratory Techniques, and Dietetics. Methods. Students completed a self-administered questionnaire designed to assess their knowledge/attitudes re/ HIV and their own sexual practices. The general part of the questionnaire requested information about age, gender, nationality, religion and marital status. The second part included questions asking about knowledge, attitude and practices with respect to HIV, which required true/false answers or graduated answers (reported as agree, quite agree, quite disagree, and disagree). Results. Four hundred students were invited to fill in the questionnaire. The response rate was 91.2% (n=365). Almost all students were aware that HIV is transmitted through sexual intercourse and blood, but only 34% knew that breastfeeding is a route of transmission. Of the respondents, 86.8% referred to previous sexual intercourse (25.8% reported using a condom in all cases of sexual intercourse, 43.5% in most cases, 18.6% rarely and 12.1 never). Sexual intercourse with casual partners was reported by 37.5% of these students and 63.9% of them did not always use a condom. Conclusions. The results of the study show that knowledge about some aspects of HIV is insufficient even though the students participating in the present study are students attending university courses related to the healthcare professions. Moreover, high-risk behaviors as the lack of the use of condom during sexual intercourse with casual partners are also common among interviewed students. Programs aimed at providing information that can prevent/reduce transmission of HIV in young people and new strategies to improve knowledge should be stressed as a public health priority

    Physicochemical Characterization of Passive Films and Corrosion Layers by Differential Admittance and Photocurrent Spectroscopy

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    Two different electrochemical techniques, differential admittance and photocurrent spectroscopy, for the characterization of electronic and solid state properties of passive films and corrosion layers are described and critically evaluated. In order to get information on the electronic properties of passive film and corrosion layers as well as the necessary information to locate the characteristic energy levels of the passive film/electrolyte junction like: flat band potential (Ufb), conduction band edge (EC) or valence band edge (EV), a wide use of Mott-Schottky plots is usually reported in corrosion science and passivity studies. It has been shown, in several papers, that the use of simple M-S theory to get information on the electronic properties and energy levels location at the film/electrolyte interface can be seriously misleading and/or conflicting with the physical basis underlying the M-S theory. A critical appraisal of this approach to the study of very thin and thick anodic passive film grown on base-metals (Cr, Ni, Fe, SS etc..) or on valve metals (Ta, Nb, W etc..) is reported in this work, together with possible alternative approach to overcome some of the mentioned inconsistencies. At this aim the theory of amorphous semiconductor Schottky barrier, introduced several years ago in the study of passive film/electrolyte junction, is reviewed by taking into account some of the more recent results obtained by the present authors. Future developments of the theory appears necessary to get more exact quantitative information on the electronic properties of passive films, specially in the case of very thin film like those formed on base metals and their alloys. The second technique described in this chapter, devoted to the physico-chemical characterization of passive film and corrosion layers, is a more recent technique based on the analysis of the photo-electrochemical answer of passive film/electrolyte junction under illumination with photons having suitable energy. Such a technique usually referred to as Photocurrent Spectroscopy (PCS) has been developed on the basis of the large research effort carried out by several groups in the 1970’s and aimed to investigate the possible conversion of solar energy by means of electrochemical cells. In this work the fundamentals of semiconductor/electrolyte junctions under illumination will be highlighted both for crystalline and amorphous materials. The role of amorphous nature and film thickness on the photo-electrochemical answer of passive film/solution interface is reviewed as well the use of PCS for quantitative analysis of the film composition based on a semi-empirical correlation between optical band gap and difference of electronegativity of film constituents previously suggested by the present authors. In this frame the results of PCS studies on valve metal oxides and valve metal mixed oxides will be discussed in order to show the validity of the proposed method. The results of PCS studies aimed to get information on passive film composition and carried out by different authors on base metals (Fe, Cr, Ni) and their alloys, including stainless steel, will be also compared with compositional analysis carried out by well-established surface analysis techniques
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