980 research outputs found

    Testing Taylor’s Law in Urban Population Dynamics Worldwide with Simultaneous Equation Models

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    Knowledge of long-term population trends is still incomplete at the global scale. In this perspective, human and animal ecology has intensively studied the relationship between the Mean (M) size and the Variance (V) of specific attributes of subpopulations within a given regional system. One of the best-known relationships between these two attributes suitable to describe long-term population trends is governed by Taylor’s law (TL). The present article contributes to the recent literature on population trends worldwide by testing the long-term relationship (1950–2015) between the overall variance and mean in the total population of 1857 metropolitan agglomerations in 155 countries classified into 9 world macro-regions. To estimate the unknown parameter(s) of the V–M relation we made use of a simultaneous equation system using both linear (classical TL) and quadratic specifications, with the aim of ascertaining a wide range of simplified (or more complex) association rules between the two dimensions of demographic change. The empirical results show that TL is verified in all nine cases, although a quadratic relationship provides slightly better results than the classical, linear relationship. More specifically, similar estimates for both linear and quadratic relationships were characteristic of ‘new’ demographic continents with more recent and intense urbanization processes (the Americas, and African and Asian countries). The predominance of quadratic relationships characterized regions with long-established urbanization processes, such as Europe, Russia, and, partly, China and the Middle East. The relevance of the TL for a refined understanding of urbanization mechanisms worldwide, and the importance of a quadratic term for distinguishing metropolitan systems that have experienced different development paths, were finally discussed

    Mesenchymal stem cells for the treatment of psoriasis: a comprehensive review

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    Mesenchymal stem cells (MSCs) have recently been shown to have not only regenerative capabilities but also immunomodulating properties. For this reason, they are currently under investigation in clinical trials for the treatment of several autoimmune systemic disorders. Psoriasis is a systemic immune-mediated disease for which MSCs could have therapeutic potential. We analysed the existing literature with regard to MSC-based strategies for the treatment of psoriasis, using the MEDLINE, Embase, Scopus and Cochrane Library electronic databases from inception to the date of study. A number of studies confirm the involvement of MSCs in psoriasis pathogenesis and therefore designate MSCs as an important potential therapeutic tool in this setting. Preclinical data are mostly based on imiquimod-induced murine models of psoriasis, and confirm the anti-inflammatory and immunomodulatory action of MSCs in the setting of psoriasis. Six patients affected by psoriasis were described in four clinical studies. Despite significant differences in terms of therapeutic protocols and clinical outcomes, the MSC-based regimens were efficacious in 100% of the cases. Despite more data still being needed, MSCs could be a promising therapy for psoriasis

    Mesenchymal stromal cells promote the proliferation of basal stem cells and efficient epithelization in organotypic models of wound healing

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    Adipose derived mesenchymal stromal cells (ADSCs) represent a fascinating tool in the scenario of wound healing and regenerative medicine. Recent data already demonstrated that ADSCs could exert a stimulatory action on epithelial cells through secretion of soluble factors. The aim of the present study was to assess how ADSCs guide wound re-epithelization in vitro in the presence of keratinocytes. We used an organotypic model of wound healing and we seeded keratinocytes on a ADSC-induced dermal matrix. Conventional hematoxylin–eosin stain and immunohistochemistry staining for Ki67, p63 and pan-keratins were performed at different timepoints. Histological sections of organotypic cultures showed complete coverage of the ADSC-induced matrix by keratinocytes. Proliferation of basal stem cells was found to be the main mechanism responsible for epithelization of the dermis. In conclusion, ADSC do not only stimulate dermal regeneration through collagen deposition but also promote epithelization

    Histopatología del osteosarcoma

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    El diagnóstico del osteosarcoma plantea una serie de problemas específicos. De hecho, se debe tener en cuenta la existencia de diversas variantes, con pronósticos diferentes y que requieren enfoques terapéuticos igualmente distintos. En este mismo sentido, la introducción de nuevos protocolos terapéuticos, incluyendo la quimioterapia preoperatoria, requiere una evaluación histopatológica cuidadosa del especimen a fin de cuantificar la necrosis inducida por la quimioterapia y los márgenes quirúrgicos. El presente estudio analiza las diferentes variantes histopatológicas y los problemas que se relacionan con la evaluación de los efectos de la quimioterapia preoperatoria sobre el especimen resecado.Diagnosis of osteosarcoma presents specific problems. In fact, several and different varieties, presenting different prognosis and requiring different treatments, have to be recognized. Moreover, the adoption of new therapeutic protocols including preoperative chemotherapy, requires a careful histopathological evaluation of the specimen to quantify the chemotherapy-induced necrosis and the surgical margins. This paper analyzes the different histopathological varieties and problems related to the evaluation of the effects on the resected specimen of preoperative chemotherapy

    Pumice and lapillus scraps: New national environmental-friendly chance for the production of ceramic tiles

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    Italian pumice and volcanic lapillus scraps have been used in different percentages as alternative raw materials to foreign feldspars in porcelain stoneware mixtures. The aim of this work was to create naturally colored support to limit the use of artificial dyes while maintaining the technical properties of the reference product. For this purpose, the significant presence of chromophores (Fe and Ti in particular) in by-products from extraction of Italian volcanic pumice and lapillus was exploited. The work was carried out in collaboration with a company: the products were made on a laboratory scale and then they were glazed and fired within the industrial production cycle (48 min, 1210 â—¦C). The resulting slip and the fired samples were characterized by measuring the efflux time, density, linear shrinkage, water absorption and tensile strength to evaluate the technological performance. In addition, thermogravimetric analysis (TG), differential thermal analysis (DTA), and optical and mechanical dilatometry were performed to study the thermal behavior of the formulations. The obtained products could be classified as porcelain stoneware and belong to the BIa group (WA 0.5%, B. S.>35 MPa) in accordance with UNI EN 14411 ISO 13006

    Validation of the italian version of the behavioral inhibition questionnaire (Biq) for preschool children

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    Behavioral Inhibition (BI) is a temperamental trait characterized by fear and wariness in reaction to new and unfamiliar stimuli, both social and non-social. BI has been recognized as possible forerunner of anxiety disorders, especially social anxiety and phobia; therefore, its assessment is clinically relevant. The present study aimed to examine the psychometric properties of the Italian adaptation of the Behavioral Inhibition Questionnaire (BIQ), which measures BI in preschool children. The BIQ was completed by 417 Italian parents (230 mothers, 187 fathers) of 270 preschoolers aged 3–5. Confirmatory factor analysis showed a good internal validity: the factorial structure was corresponding to the original six-factor version. Results showed excellent internal consistency, significant item-total correlations, good inter-rater reliability, convergent validity (by correlating the BIQ with the Italian Questionnaires of Temperament-QUIT, the Anxiety-Shy Conner’s Scale and the Laboratory Temperament Assessment Battery) and discriminant validity (i.e., no correlation with Conners’ ADHD scale). Significant correlations emerged between BI indexes and total BIQ scores of parents and maternal (but not paternal) versions of the questionnaire. Altogether, the results are promising and consistent with previous validation studies, suggesting the BIQ as a reliable and valid measure for evaluating parents’ perception of BI in Italian preschoolers

    Barkhausen instabilities from labyrinthine magnetic domains

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    Experimental investigations of the scaling behavior of Barkhausen avalanches in out-of-plane ferromagnetic films yield widely different results for the values of the critical exponents despite similar labyrinthine domain structures, suggesting that universality may not hold for this class of materials. Analyzing a phase field model for magnetic reversal, we show that avalanche scaling is bounded by characteristic lengthscales arising from the competition between dipolar forces and exchange interactions. We compare our results with the experiments and find a good qualitative and quantitative agreement, reconciling apparent contradictions. Finally, we make some prediction, amenable to experimental verification, on the dependence of the avalanches behavior from the film thickness and disorder

    Role of vacuum fluctuation forces in thin metal film stability

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    Thin metal films are subject to the pressure caused by the zero point oscillations of the electromagnetic field, which depends upon the film optical properties and, in case of deposition onto a substrate, upon the substrate reflectivity. It has been suggested that this force may be relevant in determining the stability of deposited pseudomorphic films with respect to buckling or island formation. We present a detailed analysis of its behaviour as a function of the optical parameters and of the film thickness and we illustrate the conditions under which it may play some role. For free standing films it turns out that the film stabilization is basically due to the surface stress, which largely overwhelms the vacuum force. For epilayers on metal substrate the vacuum force may be important, and we give stability diagrams and critical thicknesses for several cases, illustrating how the flat surface growth may depend upon the film parameters. The importance of including retardation effects into the theory for a realistic determination of the stability conditions is also discussed

    Mother to child transmission of Hepatitis C Virus in a province of Northern Italy

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    NTRODUCTION: Study reports of mother to child transmission of hepatitis C virus (HCV) have shown transmission rates ranging from 3 to 37%, according to maternal viremia and HIV-1 coinfection. The present study evaluated the prevalence of the HCV infection in the general population and the incidence of vertical transmission, from women who delivered in the Obstetric Clinic of the Hospital of Parma from January 1st 1996 to 31st 2001 December. METHODS: Mothers and children were tested for the presence of HCV-RNA within one week after delivery. Children were considered to be infected when they were found positive at least twice for viral RNA or antibodies were still detectable at the end of the follow-up period (18 months) in blood. RESULTS: Out of 13,025 women, 110 (0.8%) were found positive for anti-HCV antibodies; 72 of them (65.4%) were HCV-RNA positive. All 110 children were positive for anti-HCV antibodies in the first blood sample (time 0); 8 of them were HCV-RNA positive. Three children were still viremic at the end of the follow-up whereas 5 showed a clearance. No significant differences were found between viremic and nonviremic children with respect to gestational week, maternal alanine aminotransferase (ALT) levels and newborns weight at birth. CONCLUSION: This investigation shows that vertical transmission may occur in a general obstetric population despite a low prevalence of HCV-positive subjects
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