108 research outputs found

    Analysis of a heterogeneous kinetic model for traffic flow

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    In this work we extend a recent kinetic traffic model to the case of more than one class of vehicles, each of which is characterized by few different microscopic features. We consider a Boltzmann-like framework with only binary interactions, which take place among vehicles belonging to the various classes. Our approach differs from the multi-population kinetic model based on a lattice of speeds because here we assume continuous velocity spaces and we introduce a parameter describing the physical velocity jump performed by a vehicle that increases its speed after an interaction. The model is discretized in order to investigate numerically the structure of the resulting fundamental diagrams and the system of equations is analyzed by studying well posedness. Moreover, we compute the equilibria of the discretized model and we show that the exact asymptotic kinetic distributions can be obtained with a small number of velocities in the grid. Finally, we introduce a new probability law in order to attenuate the sharp capacity drop occurring in the diagrams of traffic.Comment: 31 page

    Analysis of a multi-population kinetic model for traffic flow

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    In this work we extend a recent kinetic traffic model [G. Puppo, M. Semplice, A. Tosin, G. Visconti, Kinet. Relat. Models, in press, 2016] to the case of more than one class of vehicles, each of which is characterized by few different microscopic features. We consider a Boltzmann-like framework with only binary interactions, which take place among vehicles belonging to the various classes. Our approach differs from the multi-population kinetic model proposed in [G. Puppo, M. Semplice, A. Tosin, G. Visconti, Commun. Math. Sci., 14:643-669, 2016] because here we assume continuous velocity spaces and we introduce a parameter describing the physical velocity jump performed by a vehicle that increases its speed after an interaction. The model is discretized in order to investigate numerically the structure of the resulting fundamental diagrams and the system of equations is analyzed by studying well posedness. Moreover, we compute the equilibria of the discretized model and we show that the exact asymptotic kinetic distributions can be obtained with a small number of velocities in the grid. Finally, we introduce a new probability law in order to attenuate the sharp capacity drop occurring in the diagrams of traffic

    Serum 27-hydroxycholesterol in patients with primary biliary cirrhosis suggests alteration of cholesterol catabolism to bile acids via the acidic pathway

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    Reduced cholesterol synthesis has been reported in patients with primary biliary cirrhosis but no data are available on changes in cholesterol catabolism induced by the disease. Serum levels of 7α-hydroxycholesterol and 27-hydroxycholesterol have been measured in 25 patients (either normocholesterolemic or hypercholesterolemic) with primary biliary cirrhosis and in control subjects. To evaluate cholesterol synthesis, serum levels of lathosterol were measured, and campesterol and sitosterol were considered to reflect intestinal absorption and biliary elimination of sterols. In normocholesterolemic patients with primary biliary cirrhosis, lathosterol was significantly lower than in normocholesterolemic controls (P < 0.05) whereas no difference was found between hypercholesterolemic patients and hypercholesterolemic controls. Serum concentrations of sitosterol were significantly higher in both normocholesterolemic and hypercholesterolemic patients with primary biliary cirrhosis as compared with the respective controls (P < 0.01). In patients with primary biliary cirrhosis, serum 7α-hydroxycholesterol was slightly higher than in controls. 27-Hydroxycholesterol was significantly higher in hypercholesterolemic compared to normocholesterolemic controls (P < 0.05) and a significant linear correlation (r = 0.771; P < 0.001) was found between 27-hydroxycholesterol and cholesterol. In contrast, in patients with primary biliary cirrhosis, high cholesterol concentrations were not associated with increased serum levels of 27-hydroxycholesterol. Our data confirm that in patients with primary biliary cirrhosis, cholesterol synthesis and biliary elimination of sterols are impaired and also suggest that both the feedback regulation of retained bile acids on cholesterol 7α-hydroxylase and the scavenger effect on elevated serum cholesterol by cholesterol 27-hydroxylase are deficient in these patients.—Del Puppo, M., M. Galli Kienle, M. L. Petroni, A. Crosignani, and M. Podda. Serum 27-hydroxycholesterol in patients with primary biliary cirrhosis suggests alteration of cholesterol catabolism to bile acids via the acidic pathway. J. Lipid Res. 1998. 39: 2477–2482

    Urbanismo epidémico. La medicalización de la vida urbana en Montevideo en el primer tercio del siglo XX

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    The consolidation of the modern Uruguayan state is largely due to the establishment of medical knowledge as a progressive element of social order. In the first decades of the 20th century, health was positioned as an absolute value and this had repercussions in all areas of social and urban life. As a result, plans, regulations, competitions and interventions responded not only to the hygienist paradigm extended throughout the second half of the 19th century as a form of urban improvement, but also as a tool for establishing a new social order. The role of the state, public spaces and the architectural profession require reflections that lead to new urban planning –and that go beyond the professional absolutism of hygienism–.La consolidación del Estado moderno uruguayo se debe, en gran parte, al establecimiento del saber médico como elemento progresista y de orden social. En las primeras décadas del siglo XX, la salud se posiciona como valor absoluto y esto repercute en todos los ámbitos de la vida social y urbana. Como resultado, los planes, normativas, concursos e intervenciones van a responder al paradigma higienista extendido desde la segunda mitad del siglo XIX como forma de mejora urbana, pero también como herramienta para establecer un nuevo orden social. El rol del Estado, los espacios públicos y la profesión arquitectónica, requieren reflexiones que devengan en nuevos urbanismos –y que superen el absolutismo profesional del higienismo–

    Characterization of soluble and insoluble fibers in artichoke by-products by ATR-FTIR spectroscopy coupled with chemometrics

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    The objective of this study was to characterize the insoluble and soluble dietary fiber present in Argentine and Italian artichoke (Cynara scolymus) by-products by comparing chemical analysis and ATR-FTIR spectroscopy. Non-edible bracts of Argentine (AR) and Italian (Benevento (BN) and Sicily (SC)) artichoke cultivars were employed. The soluble and insoluble dietary fibers were extracted by physical procedures and determined by chemical, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, and chemometric analysis (principal components analysis, PCA). No differences in total dietary fiber content between AR and SC samples were observed, although they both showed higher values than BN. With respect to insoluble fiber, this fraction represents 82.5%, 63.5%, and 55.2% of the total dietary fiber for BN, SC and AR, respectively. Fibers from AR presented different compositions and structures, as determined by ATR-FTIR, compared to those of the Italian cultivars (BN and SC). Comparing the results of dietary fiber measured by ezymogravimetric assay with those obtained by ATR-FTIR and PCA, we conclude that it is possible to discriminate samples that contain different kinds of fiber using ATR-FTIR.Fil: Quintero Ruiz, Natalia Andrea. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Paolucci, M.. Consiglio Nazionale delle Ricerche; Italia. Università Degli Studi del Sannio; ItaliaFil: Siano, Francesco. Consiglio Nazionale delle Ricerche; ItaliaFil: Mamone, Gianfranco. Consiglio Nazionale delle Ricerche; ItaliaFil: Picariello, Gianluca. Consiglio Nazionale delle Ricerche; ItaliaFil: Puppo, Maria Cecilia. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigación y Desarrollo en Criotecnología de Alimentos. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Centro de Investigación y Desarrollo en Criotecnología de Alimentos; ArgentinaFil: Cascone, G.. Consiglio Nazionale delle Ricerche; ItaliaFil: Volpe, M. G.. Consiglio Nazionale delle Ricerche; Itali

    Autoimmune central diabetes insipidus in a patient with ureaplasma urealyticum infection and review on new triggers of immune response

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    Diabetes insipidus is a disease in which large volumes of dilute urine (polyuria) are excreted due to vasopressin (AVP) deficiency [central diabetes insipidus (CDI)] or to AVP resistance (nephrogenic diabetes insipidus). In the majority of patients, the occurrence of CDI is related to the destruction or degeneration of neurons of the hypothalamic supraoptic and paraventricular nuclei. The most common and well recognized causes include local inflammatory or autoimmune diseases, vascular disorders, Langerhans cell histiocytosis (LCH), sarcoidosis, tumors such as germinoma/craniopharyngioma or metastases, traumatic brain injuries, intracranial surgery, and midline cerebral and cranial malformations. Here we have the opportunity to describe an unusual case of female patient who developed autoimmune CDI following ureaplasma urealyticum infection and to review the literature on this uncommon feature. Moreover, we also discussed the potential mechanisms by which ureaplasma urealyticum might favor the development of autoimmune CDI

    A biology-driven approach identifies the hypoxia gene signature as a predictor of the outcome of neuroblastoma patients

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    Background Hypoxia is a condition of low oxygen tension occurring in the tumor microenvironment and it is related to poor prognosis in human cancer. To examine the relationship between hypoxia and neuroblastoma, we generated and tested an in vitro derived hypoxia gene signature for its ability to predict patients' outcome. Results We obtained the gene expression profile of 11 hypoxic neuroblastoma cell lines and we derived a robust 62 probesets signature (NB-hypo) taking advantage of the strong discriminating power of the l1-l2 feature selection technique combined with the analysis of differential gene expression. We profiled gene expression of the tumors of 88 neuroblastoma patients and divided them according to the NB-hypo expression values by K-means clustering. The NB-hypo successfully stratifies the neuroblastoma patients into good and poor prognosis groups. Multivariate Cox analysis revealed that the NB-hypo is a significant independent predictor after controlling for commonly used risk factors including the amplification of MYCN oncogene. NB-hypo increases the resolution of the MYCN stratification by dividing patients with MYCN not amplified tumors in good and poor outcome suggesting that hypoxia is associated with the aggressiveness of neuroblastoma tumor independently from MYCN amplification. Conclusions Our results demonstrate that the NB-hypo is a novel and independent prognostic factor for neuroblastoma and support the view that hypoxia is negatively correlated with tumors' outcome. We show the power of the biology-driven approach in defining hypoxia as a critical molecular program in neuroblastoma and the potential for improvement in the current criteria for risk stratification.Foundation KiKaChildren's Neuroblastoma Cancer FoundationSKK FoundationDutch Cancer Societ
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