5,151 research outputs found

    The 2D/3D dynamics of wall-bounded low-Rm magnetohydrodynamic (MHD) turbulence

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    With this experimental study, we give evidence that the dynamics of low-Rm MHD turbulence depends on the diffusion length l_z, which corresponds to the distance over which the Lorentz force is able to diffuse momentum before it is balanced by inertia

    Triangular Constellations in Flows

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    Particles advected on the surface of a fluid can exhibit fractal clustering. The local structure of a fractal set is described by its dimension DD, which is the exponent of a power-law relating the mass N{\cal N} in a ball to its radius ε\varepsilon: NεD{\cal N}\sim \varepsilon^D. It is desirable to characterise the {\em shapes} of constellations of points sampling a fractal measure, as well as their masses. The simplest example is the distribution of shapes of triangles formed by triplets of points, which we investigate for fractals generated by chaotic dynamical systems. The most significant parameter describing the triangle shape is the ratio zz of its area to the radius of gyration squared. We show that the probability density of zz has a phase transition: P(z)P(z) is independent of ε\varepsilon and approximately uniform below a critical flow compressibility βc\beta_{\rm c}, which we estimate. For β>βc\beta>\beta_{\rm c} the distribution appears to be described by two power laws: P(z)zα1P(z)\sim z^{\alpha_1} when 1zzc(ε)1\gg z\gg z_{\rm c}(\varepsilon), and P(z)zα2P(z)\sim z^{\alpha_2} when zzc(ε)z\ll z_{\rm c}(\varepsilon)

    The Post-Graduate Program on Child and Woman Health of Instituto Fernandes Figueira (Oswaldo Cruz Foundation) and its insertion in the public health area

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    Fundação Oswaldo Cruz. Instituto Fernandes Figueira. Departamento de Ensino. Rio de Janeiro, RJ, BrasilFundação Oswaldo Cruz. Instituto Fernandes Figueira. Departamento de Ensino. Rio de Janeiro, RJ, BrasilFundação Oswaldo Cruz. Instituto Fernandes Figueira. Departamento de Ensino. Rio de Janeiro, RJ, BrasilFundação Oswaldo Cruz. Instituto Fernandes Figueira. Departamento de Ensino. Rio de Janeiro, RJ, Brasi

    Rm 10,5-15: Tradução e impacto retórico

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    The Holy Scriptures fascinate millions of people and, over them, there are dedication and efforts by exegetes, biblical theologians, sociologists, anthropologists, archaeologists, etc. While some of them work using the original language texts (Hebrew, Aramaic and Greek), others use vernacular translations. The fact is that a translation, no matter how faithful it tries to be, in a way, it is an interpretation, due to the terminological choice of the target language, which is not always able to achieve the polysemy of the text in the original language. The prologue of the book of Ecclesiasticus already pointed to this. So, as much as translators try and try to be “impartial”, there are hermeneutical assumptions that are hardly left aside in the act of translating. There is not, so to speak, a complete objective translation. In this sense, the present paper proposes to offer a segmented translation of Rm 10,5-15 from the Koine Greek with which it was written, followed by a syntactic-grammatical analysis, seeking to verify the internal logic of the terminology used in the elaboration of the propositions, allowing the translation to be as consistent as possible with the original meaning. Furthermore, the article submits the text in question, from a methodological point of view, to Greco-Latin and Semitic rhetorical analysis, since in Rom 10,5-15 there are several quotations and allusions to Old Testament texts. It is believed that the adoption of these procedures is valid to obtain a translation more consistent with the original language and with the meanings that were intended by the author. Keywords: Bible. Religious literature. Linguistics. Methodology. Translation.As Sagradas Escrituras fascinam milhões de pessoas e sobre elas há dedicação e empenho nos estudos por parte de exegetas, teólogos bíblicos, sociólogos, antropólogos, arqueólogos etc. Enquanto alguns trabalham a partir dos textos em línguas originais (Hebraico, Aramaico e Grego), outros se valem de traduções em vernáculo. Fato é que uma tradução, por mais fiel que procure ser, de certa forma, já é uma interpretação devido à escolha da terminologia da língua de destino, a qual nem sempre é capaz de alcançar a polissemia do texto na língua original. O prólogo do livro do Eclesiástico já apontava para isso. Então, por mais que os tradutores se esforcem e procurem ser “imparciais”, existem pressupostos hermenêuticos que dificilmente são deixados de lado no ato de traduzir. Não há, por assim dizer, uma tradução totalmente objetiva. Neste sentido, o presente artigo se propõe a oferecer uma tradução segmentada de Rm 10,5-15 a partir do grego koiné com o qual foi escrito, seguida de uma análise sintático-gramatical, buscando verificar a lógica interna da terminologia empregada na elaboração das proposições, permitindo que a tradução seja a mais condizente possível com o sentido original. Além disso, o artigo submete o texto em questão, do ponto de vista metodológico, à análise retórica greco-latina e semítica, pois em Rm 10,5-15 existem várias citações e alusões a textos veterotestamentários. Acredita-se que a adoção desses procedimentos é válida para se obter uma tradução mais condizente com a língua original e com os sentidos que foram pretendidos pelo autor

    Exact two-dimensionalization of low-magnetic-Reynolds-number flows subject to a strong magnetic field

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    We investigate the behavior of flows, including turbulent flows, driven by a horizontal body-force and subject to a vertical magnetic field, with the following question in mind: for very strong applied magnetic field, is the flow mostly two-dimensional, with remaining weak three-dimensional fluctuations, or does it become exactly 2D, with no dependence along the vertical? We restrict attention to low-magnetic-Reynolds number (Rm) flow. Because liquid metals have low magnetic Prandtl number, such low-RmRm flows can have a kinetic Reynolds number as large as one million and therefore be strongly turbulent. We first focus on the quasi-static approximation, i.e. the asymptotic limit of vanishing magnetic Reynolds number Rm << 1: we prove that the flow becomes exactly 2D asymptotically in time, regardless of the initial condition and provided the interaction parameter N is larger than a threshold value. We call this property absolute two-dimensionalization: the attractor of the system is necessarily a (possibly turbulent) 2D flow. We then consider the full-magnetohydrodynamic equations and we prove that, for low enough Rm and large enough N, the flow becomes exactly two-dimensional in the long-time limit provided the initial vertically-dependent perturbations are infinitesimal. We call this phenomenon linear two-dimensionalization: the (possibly turbulent) 2D flow is an attractor of the dynamics, but it is not necessarily the only attractor of the system. Some 3D attractors may also exist and be attained for strong enough initial 3D perturbations. These results shed some light on the existence of a dissipative anomaly for magnetohydrodynamic flows subject to a strong external magnetic field

    The Decay of Wall Bounded MHD Turbulence at Low RM

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    We have developed a new spectral method to simulate flows with very fine boundary layers present. We apply it to calculate the evolution of freely decaying MHD turbulence between isolating walls. By comparison them with results obtained in fully periodic domain we quantify the influence of the channel walls on the character of freely decaying MHD turbulence

    A basis of a certain module for the hyperalgebra (SL2)r({\rm SL}_2)_r and some applications

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    In the hyperalgebra Ur\mathcal{U}_r of the rr-th Frobenius kernel (SL2)r({\rm SL}_2)_r of the algebraic group SL2{\rm SL}_2, we construct a basis of the Ur\mathcal{U}_r-module generated by a certain element which was given by the author before. As its applications, we also prove some results on the Ur\mathcal{U}_r-modules and the algebra Ur\mathcal{U}_r.Comment: 30 page

    Borromini tuscolano

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    La pubblicazione propone, in versione ampliata e aggiornata, la chiave di lettura già avanzata dall’autore alcuni anni or sono in relazione all’intervento seicentesco voluto dalla famiglia Falconieri sulla più antica delle Ville Tuscolane, la Rufina, ritenendone valida la consolidata attribuzione al Borromini. Nel volume viene data un’ampia dimostrazione dell’efficacia dell’interazione “documenti storici-rilievo architettonico”, nella ricostruzione delle fasi evolutive di una fabbrica e di come questo momento d’analisi, ove insufficientemente approfondito, possa indurre a considerazioni erronee. Infatti, l’ipotesi diffusa in vari contributi sull’argomento riguardo alla forma dell’originario Casino della Rufina – e in particolare alla posizione della loggia verso Roma – è suffragata soltanto da incisioni d’epoca e non è mai stata scientificamente comprovata dal riscontro di un rilievo, né dal confronto attento con la pianta del nucleo originario della fabbrica conservata nelle Carte Strozzi presso l’Archivio di Stato di Firenze, ignorata o considerata – con una certa superficialità – come inattendibile. L’ipotesi qui sostenuta valuta la “logica” dell’addizione alla Villa Rufina basandosi su considerazioni relative sia ai vari documenti iconografici sia all’attendibilità di ciascuno; il tutto è inoltre riferito al completo rilevamento dell’opera nel suo stato attuale. Discutendo ipotesi diverse (anche attributive) emerse nel frattempo e sviluppando le considerazioni precedentemente avanzate grazie anche a un nuovo apparato iconografico che vede sfruttate le potenzialità della modellazione 3D applicate ai criteri del rilievo filologico, il lavoro tende a ribadire l’efficacia di tale metodo d’indagine, basato sul rilievo delle attuali condizioni dell’opera in associazione all’imprescindibile analisi storico-documentale. Attraverso il medesimo impianto scientifico procedurale è inoltre sviluppata la ricostruzione filologica del fronte settentrionale, basata anche su documentazione fotografica d’epoca parzialmente inedita. Si intende così offrire un iniziale – seppur parziale – contributo alla rilettura dell’ultima fase (quella novecentesca) che ha contrassegnato la fabbrica, vedendola già alterata ai primi del XX secolo, quindi compromessa dagli eventi bellici e infine trasformata dalle operazioni di restauro/ripristino del complesso, che hanno riproposto solo parzialmente e in modo generico la precedente morfologia del manufatto.This publication proposes, in an expanded and updated version, the key that the Author had already advanced in an earlier essay which was published ten years ago, concerning the 17th century intervention on the Villa Rufina: the first one of the Ville Tuscolane (summer residences for the papal circle that rose, in the late Renaissance, on the hills at the south of Rome). The Authors assumes also to be valid the well-established attribution of this work to Francesco Borromini. In this volume a wide demonstration is offered of the efficacy, for the aim of a reliable reconstruction of the evolutionary phases of a certain building, of the interaction between the historical documents and the architectural survey, showing also how this time of analysis can lead to incorrect or misleading considerations, when it is not carried out enough deeply. In the second phase (the expansion of the 17th century) which characterized all the Ville Tuscolane, the Rufina, at the time owned by the Falconieri (family), was the subject of an extensive renewal. With this intervention the first bulding that had initiated the “modern rediscovery” of building activity in these places (being, in fact, the originator of the Complex) was considerably transformed with regard to its material structure, appearance and relationship with the environment. For the devising of the general plan, it is commonly ascribed to Francesco Borromini, on the basis more of archive documents than of its style. If the decoration of the Villa has been extensively and reliably studied, the same cannot be said about the transformations that the old building underwent, especially with regard to the lost loggia towards Rome. The hypothesis that has gradually taken root, about the location of this lodge, in the various papers published on the subject, is in fact supported only by some engravings of the time (in which the Villa is depicted in a pseudo-perspectival view and only as an element amongst the many others of the Complex). It has never been scientifically proved by the check of a survey, or by a careful comparison with the plan of the original nucleus of the original factory map stored in the “Carte Strozzi” at the State Archives of Florence, that has been ignored or considered – with some superficiality – as unreliable. The hypothesis the Author suggested since the previous essay, evaluates the “logic” of the addition Borromini made to the Villa Rufina detaching itself from these assumptions and basing itself on some specific considerations concerning the iconographic documents that have been published over the years in various contributions, evaluating the reliability of each of them. These considerations were also related to a comprehensive survey of the work in its current state, as the so far published surveys are partial or were carried out on the structure as extensively damaged by the war. In the volume are also discussed several different hypotheses that emerged in the meantime, also on the allocation of the project, as the attribution to Borromini – which in the past had seen ups and downs, from the header of the engraving by Alessandro Specchi to the evidences provided by Paolo Portoghesi and by Angela Negro, taken from the Falconieri-Carpegna archive – has recently been the subject of a new attempt of denial. Developing the considerations already advanced before, and using a new display of subsidiary iconography that sees the exploitation of the potential of 3d modeling when applied to the criteria of the philological surveying, this study aims at a confirmation of the effectiveness of this method of investigation, which is based on a survey of the work in its positive state in conjunction with an unavoidable historical-documentary analysis. On the basis of this same scientific procedural system, taking as well in account many historical photographic documents, so far unpublished, is also developed a philological reconstruction of the northern front, that is proposed in the last chapter. The aim is to provide a first – although partial – contribution to the re-reading of the last phase (the 20th century), which marked the building, that had already been altered in the early years of the 20th century, then compromised by the war and finally transformed by the restoration and rehabilitation of the complex, which reconstructed the pre-existing morphology only in a partial and general way

    Measuring KS0^0_{\rm S}K±^{\rm \pm} interactions using Pb-Pb collisions at sNN=2.76{\sqrt{s_{\rm NN}}=2.76} TeV

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    We present the first ever measurements of femtoscopic correlations between the KS0 and K ± particles. The analysis was performed on the data from Pb–Pb collisions at sNN=2.76 TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding via the a0(980) resonance. The extracted kaon source radius and correlation strength parameters for KS0K− are found to be equal within the experimental uncertainties to those for KS0K+ . Comparing the results of the present study with those from published identical-kaon femtoscopic studies by ALICE, mass and coupling parameters for the a0 resonance are tested. Our results are also compatible with the interpretation of the a0 having a tetraquark structure instead of that of a diquark.We present the first ever measurements of femtoscopic correlations between the KS0^0_{\rm S} and K±^{\rm \pm} particles. The analysis was performed on the data from Pb-Pb collisions at sNN=2.76\sqrt{s_{\rm NN}}=2.76 TeV measured by the ALICE experiment. The observed femtoscopic correlations are consistent with final-state interactions proceeding via the a0(980)a_0(980) resonance. The extracted kaon source radius and correlation strength parameters for KS0^0_{\rm S}K^{\rm -} are found to be equal within the experimental uncertainties to those for KS0^0_{\rm S}K+^{\rm +}. Comparing the results of the present study with those from published identical-kaon femtoscopic studies by ALICE, mass and coupling parameters for the a0a_0 resonance are constrained. Our results are also compatible with the interpretation of the a0a_0 having a tetraquark structure over that of a diquark

    Convective Ripening and Rainfall

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    This paper discusses the evolution of the droplet size distribution for a liquid-in-gas aerosol contained in a Rayleigh-B\'enard cell. It introduces a non-collisional model for broadening the droplet size distribution, termed \lq convective ripening'. The paper also considers the initiation of rainfall from ice-free cumulus clouds. It is argued that while collisional mechanisms cannot explain the production of rain from clouds with water droplet diameters of 20 μm20\ \mu {\rm m}, the non-collisional convective ripening mechanism gives a much faster route to increasing the size of the small fraction of droplets that grow into raindrops
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