1,354,132 research outputs found
Il discorso programmatico del capo del governo nella transizione italiana: una comparazione con la "prima repubblica"
No full textL'articolo si prefigge l'obiettivo di indagare, in un'ottica comparata, l'evoluzione dei discorsi politici proferiti dai Presidenti del Consiglio di fronte alle camere ad inizio mandato, nel passaggio dalla Prima alla Seconda Repubblica. I risultati della ricerca, che si avvale, per l'indagine dei discorsi, della tecnica nota come analisi del contenuto, mostrano l'esistenza di un progressivo avvicinamento dell'invocazione simbolica dei capi di governo italiani a quella tipica di capi di governo europei come i Premier inglesi o i Cancellieri tedeschi. La spiegazione del fenomeno fa leva sulla comparsa, nell'Italia post-94, di governi legittimati direttamente dal voto popolare, al pari di quelli britannici e tedeschi
Constraint-preserving boundary conditions in numerical relativity
No full textThis is the first paper in a series aimed to implement boundary conditions consistent with the constraints’ propagation in 3D unconstrained numerical relativity. Here we consider spherically symmetric black hole spacetimes in vacuum or with a minimally coupled scalar field, within the Einstein-Christoffel (EC) symmetric hyperbolic formulation of Einstein’s equations. By exploiting the characteristic propagation of the main variables and constraints, we are able to single out the only free modes at the outer boundary for these problems. In the vacuum case a single free mode exists which corresponds to a gauge freedom, while in the matter case an extra mode exists which is associated with the scalar field. We make use of the fact that the EC formulation has no superluminal characteristic speeds to excise the singularity. We present a second-order, finite difference discretization to treat these scenarios, where we implement these constraint-preserving boundary conditions, and are able to evolve the system for essentially unlimited times (i.e., limited only by the available computing time). As a test of the robustness of our approach, we allow large pulses of gauge and scalar field to enter the domain through the outer boundary. We reproduce expected results, such as trivial (in the physical sense) evolution in the vacuum case (even in gauge-dynamical simulations), and the tail decay for the scalar field.<br/
Stability properties of a formulation of Einstein's equations
No full textWe study the stability properties of the Kidder-Scheel-Teukolsky (KST) many-parameter formulation of Einstein’s equations for weak gravitational waves on flat space-time from a continuum and numerical point of view. At the continuum, performing a linearized analysis of the equations around flat space-time, it turns out that they have, essentially, no non-principal terms. As a consequence, in the weak field limit the stability properties of this formulation depend only on the level of hyperbolicity of the system. At the discrete level we present some simple one-dimensional simulations using the KST family. The goal is to analyze the type of instabilities that appear as one changes parameter values in the formulation. Lessons learned in this analysis can be applied in other formulations with similar properties.<br/
Valutazione dell'attivita antibatterica di un miele di tiglio
No full textE' stato analizzato un miele che all'analisi melissopalinologica è risultato essere costituito da una prevalenza di tiglio tale da poter essere considerato un monoflora; il suddetto miele è stato saggiato con la MIC per valutarne l'attività antibatterica nei confronti di 6 ceppi ATCC, nello specifico Enterococcus faecalis VanB V583 E, Enterococcus faecalis 19433, Pseudomonas aeruginosa 27853, Staphylococcus aureus 6539, Escherichia coli 15325, Salmonella tiphymurium 14028. Il miele ha dimostrato di possedere buona attività antibatterica nei confronti di tutti i microrganismi testati con una più spiccata azione nei confronti dei Gram positivi, nell'ordine contro gli enterococchi e poi contro lo stafilococco con valori di MIC pari a 0,026 g/m
Well posed constraint-preserving boundary conditions for the linearized Einstein equations
No full textIn this paper we address the problem of specifying boundary conditions for Einstein's equations when linearized around Minkowski space using the generalized Einstein-Christoffel symmetric hyperbolic system of evolution equations. The boundary conditions we work out guarantee that the constraints are satisfied provided they are satisfied on the initial slice and ensures a well posed initial-boundary value formulation. We consider the case of a manifold with a non-smooth boundary, as is the usual case of the cubic boxes commonly used in numerical relativity. The techniques discussed should be applicable to more general cases, as linearizations around more complicated backgrounds, and may be used to establish well posedness in the full non-linear case
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Hyperbolicity of the BSSN system of Einstein evolution equations
No full textWe discuss an equivalence between the Baumgarte-Shapiro-Shibata-Nakamura (BSSN) formulation of the Einstein evolution equations, a subfamily of the Kidder-Scheel-Teukolsky formulation, and other strongly or symmetric hyperbolic first order systems with fixed shift and densitized lapse. This allows us to show under which conditions the BSSN system is, in a sense to be discussed, hyperbolic. This desirable property may account in part for the empirically observed better behavior of the BSSN formulation in numerical evolutions involving black holes
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Inhibition of interferon-gamma-mediated microvascular endothelial cell major histocompatibility complex class II gene activation by HMG-CoA reductase inhibitors
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