46 research outputs found

    Adapting a Fourier pseudospectral method to Dirichlet boundary conditions for Rayleigh–BĂ©nard convection

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    We present the adaptation to non–free boundary conditions of a pseudospectral method based on the (complex) Fourier transform. The method is applied to the numerical integration of the Oberbeck–Boussinesq equations in a Rayleigh–BĂ©nard cell with no-slip boundary conditions for velocity and Dirichlet boundary conditions for temperature. We show the first results of a 2D numerical simulation of dry air convection at high Rayleigh number (R ∌ 10^9). These results are the basis for the later study, by the same method, of wet convection in a solar still.publishedVersionFil: Ramos, Ivana Carola. Universidad Nacional de CĂłrdoba. Facultad de MatemĂĄtica, AstronomĂ­a y FĂ­sica; Argentina.Fil: Briozzo, Carlos Bruno. Universidad Nacional de CĂłrdoba. Facultad de MatemĂĄtica, AstronomĂ­a y FĂ­sica; Argentina.FĂ­sica de los Fluidos y Plasm

    Notulae to the Italian flora of algae, bryophytes, fungi and lichens: 8

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    In this contribution, new data concerning algae, bryophytes, fungi, and lichens of the Italian flora are presented. It includes new records and confirmations for the algae genus Chara, the bryophyte genera Homalia, Mannia, and Tortella, the fungal genera Cortinarius, Russula, and Stereum, and the lichen genera Cetrelia, Cladonia, Enterographa, Graphis, Lecanora, Lepraria, Multiclavula, Mycomicrothelia, Parmelia, Peltigera, Pleopsidium, Psora, Scytinium, Umbilicaria, and Rhizocarpon

    Changes in Dynamics upon Oligomerization Regulate Substrate Binding and Allostery in Amino Acid Kinase Family Members

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    Oligomerization is a functional requirement for many proteins. The interfacial interactions and the overall packing geometry of the individual monomers are viewed as important determinants of the thermodynamic stability and allosteric regulation of oligomers. The present study focuses on the role of the interfacial interactions and overall contact topology in the dynamic features acquired in the oligomeric state. To this aim, the collective dynamics of enzymes belonging to the amino acid kinase family both in dimeric and hexameric forms are examined by means of an elastic network model, and the softest collective motions (i.e., lowest frequency or global modes of motions) favored by the overall architecture are analyzed. Notably, the lowest-frequency modes accessible to the individual subunits in the absence of multimerization are conserved to a large extent in the oligomer, suggesting that the oligomer takes advantage of the intrinsic dynamics of the individual monomers. At the same time, oligomerization stiffens the interfacial regions of the monomers and confers new cooperative modes that exploit the rigid-body translational and rotational degrees of freedom of the intact monomers. The present study sheds light on the mechanism of cooperative inhibition of hexameric N-acetyl-L-glutamate kinase by arginine and on the allosteric regulation of UMP kinases. It also highlights the significance of the particular quaternary design in selectively determining the oligomer dynamics congruent with required ligand-binding and allosteric activities

    The prevalence of stillbirths: a systematic review

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    BACKGROUND: Stillbirth rate is an important indicator of access to and quality of antenatal and delivery care. Obtaining overall estimates across various regions of the world is not straightforward due to variation in definitions, data collection methods and reporting. METHODS: We conducted a systematic review of a range of pregnancy-related conditions including stillbirths and performed meta-analysis of the subset of studies reporting stillbirth rates. We examined variation across rates and used meta-regression techniques to explain observed variation. RESULTS: We identified 389 articles on stillbirth prevalence among the 2580 included in the systematic review. We included 70 providing 80 data sets from 50 countries in the meta-analysis. Pooled prevalence rates show variation across various subgroup categories. Rates per 100 births are higher in studies conducted in less developed country settings as compared to more developed (1.17 versus 0.50), of inadequate quality as compared to adequate (1.12 versus 0.66), using sub-national sample as compared to national (1.38 versus 0.68), reporting all stillbirths as compared to late stillbirths (0.95 versus 0.63), published in non-English as compared to English (0.91 versus 0.59) and as journal articles as compared to non-journal (1.37 versus 0.67). The results of the meta-regression show the significance of two predictor variables – development status of the setting and study quality – on stillbirth prevalence. CONCLUSION: Stillbirth prevalence at the community level is typically less than 1% in more developed parts of the world and could exceed 3% in less developed regions. Regular reviews of stillbirth rates in appropriately designed and reported studies are useful in monitoring the adequacy of care. Systematic reviews of prevalence studies are helpful in explaining sources of variation across rates. Exploring these methodological issues will lead to improved standards for assessing the burden of reproductive ill-health

    Specie esotiche invasive di rilevanza unionale in Italia: aggiornamenti e integrazioni

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    La Commissione Europea (CE) ha inserito ad oggi 36 taxa esotici vegetali nella lista delle specie esotiche invasive di rilevanza unionale ai sensi del Regolamento (UE) n. 1143/2014 del Parlamento Europeo e del Consiglio, recante disposizioni volte a prevenire e gestire l’introduzione e la diffusione delle specie esotiche invasive. La lista delle specie di rilevanza unionale viene periodicamente aggiornata e include quelle specie che rappresentano una grave minaccia per la biodiversità, ma anche per la salute dei cittadini e le attività economiche nei territori dell’Unione Europea e che necessitano di una gestione concertata a livello comunitario. La CE vigila sullo stato di ogni taxon grazie anche a periodiche rendicontazioni da parte dei paesi dell'Unione. In vista di tali report, tra il 2020 e il 2021 ù stata definita e integrata la distribuzione di queste specie in Italia

    Examining life in detention: A process of survey translation and adaptation through an ecological and collaborative approach

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    This paper illustrates the process we engaged in to translate and adapt a survey to examine life in an immigration detention center in Italy from the perspective of the migrants detained therein. The process consisted of: the forward translation of the original measure performed by four independent translators; a blind backward translation to identify misinterpretations or incorrect cross-cultural and contextual adaptations; a synthesis of all translations to obtain a semifinal version; the creation of an Expert Committee composed of scholars, practitioners, and migrants with experience of detention to assess equivalence and content validity; and, finally, pretesting with a group of 15 detained persons. Through this multi-step process we obtained a measure capable of grasping the context-specific meanings, needs and experiences that characterize life in detention. The challenges and benefits of a collaborative and ecological approach to measurement translation and adaption are discussed in the final section
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