I caratteri della rivista (struttura, inchieste, almanacchi)

Fra una serie di studi apparsi nel volume Spiritualit\ue0 e utopia: la rivista \u201cCoenobium\u201d (1906-1919) (Lugano, 10 novembre-Milano, 11 novembre 2005), a cura di Fabrizio Panzera e Daniela Saresella, Milano, Cisalpino. Istituto Editoriale Universitario \u2013 Monduzzi Editore, 2007, il saggio esamina il contenuto e la struttura editoriale della rivista, in relazione al dibattito che aveva portato alla sua nascita. La rassegna luganese era sorta grazie al sodalizio fra Enrico Bignami e Arcangelo Ghisleri, con il contributo di figure quali Giuseppe Rensi, caporedattore fino al 1914, Angelo Crespi e Alfredo Poggi, passando da un primo periodo improntato alla riflessione filosofica e religiosa, con evidenti simpatie moderniste, a una seconda e pi\uf9 difficile fase legata al pacifismo ispirato da Romain Rolland, senza per\uf2 riuscire a durare nel tempo, nonostante un ultimo e coraggioso tentativo di riprendere le pubblicazioni nel 1919. Il successo della rivista \u2013 che ospita contributi sia in italiano sia in francese e diviene ben presto un\u2019autorevole tribuna della cultura italiana ed europea \u2013 si lega indubbiamente all\u2019originalit\ue0 della struttura, che prevede una nota della Direzione, una serie di articoli e saggi di varie tendenze, spesso di grande importanza culturale e speculativa, una successione di rubriche. Vanno ricordate la Tribuna del Coenobium, che accoglie i numerosi e continui interventi dei lettori, Intorno all\u2019ignoto, Nel vasto mondo, Documenti e ricordi personali, Pagine scelte (poco note o obliate), la Rassegna critica di recensioni di volumi, la Rivista delle riviste, con segnalazioni da un vasto numero di periodici nazionali e internazionali, Consensi e appunti, altro momento d\u2019incontro con il pubblico, le Note a fascio di cronaca culturale, a cui si aggiungono le Inchieste e i Concorsi di grande risonanza, destinati a fornire il materiale per gli Almanacchi. \u201cCoenobium\u201d rivendica di essere un convito di spiriti liberi e un punto d\u2019incontro di liberi studi storico-religiosi, da quelli buddistici e orientalistici a quelli ebraici, da quelli segnati dalle inquietudini del modernismo cattolico ad altri legati al radicalismo protestante, dagli orientamenti ateistici a quelli esplicitamente rivolti alla trascendenza. Prima della Pascendi e della condanna di \u201cCoenobium\u201d rivista nello stesso 1907 e in realt\ue0 anche dopo, il riscontro nel mondo cattolico \ue8 notevole, ma soprattutto sono i grandi nomi della cultura europea del primo Novecento a incontrarsi sulle pagine di una rivista capace di fornire gli strumenti adatti a una discussione fin dall\u2019inizio basata sul metodo della \u201clibert\ue0\u201d di ricerca e di giudizio

Ultra-luminous X-ray sources and remnants of massive metal-poor stars

Massive metal-poor stars might form massive stellar black holes (BHs), with mass 25<=mBH/Msun<=80, via direct collapse. We derive the number of massive BHs (NBH) that are expected to form per galaxy through this mechanism. Such massive BHs might power most of the observed ultra-luminous X-ray sources (ULXs). We select a sample of 64 galaxies with X-ray coverage, measurements of the star formation rate (SFR) and of the metallicity. We find that NBH correlates with the number of observed ULXs per galaxy (NULX) in this sample. We discuss the dependence of our model on the SFR and on the metallicity. The SFR is found to be crucial, consistently with previous studies. The metallicity plays a role in our model, since a lower metallicity enhances the formation of massive BHs. Consistently with our model, the data indicate that there might be an anticorrelation between NULX, normalized to the SFR, and the metallicity. A larger and more homogeneous sample of metallicity measurements is required, in order to confirm our results.Comment: 21 pages, 8 figures, accepted for publication in MNRA

Effects of dark matter annihilation on the first stars

We study the evolution of the first stars in the universe (Population III) from the early pre-Main Sequence until the end of helium burning in the presence of WIMP dark matter annihilation inside the stellar structure. The two different mechanisms that can provide this energy source are the contemporary contraction of baryons and dark matter, and the capture of WIMPs by scattering off the gas with subsequent accumulation inside the star. We find that the first mechanism can generate an equilibrium phase, previously known as a "dark star", which is transient and present in the very early stages of pre-MS evolution. The mechanism of scattering and capture acts later, and can support the star virtually forever, depending on environmental characteristic of the dark matter halo and on the specific WIMP model.Comment: Proceedings of the IAU Symposium 255, "Low-Metallicity Star Formation: From the First Stars to Dwarf Galaxies"; L.K. Hunt, S. Madden and R. Schneider ed

Approximation in FEM, DG and IGA: a theoretical comparison

In this paper we compare the approximation properties of degree p spline spaces with different numbers of continuous derivatives. We prove that, for a given space dimension, Cp-1 splines provide better a priori error bounds for the approximation of functions in Hp+1(0 , 1). Our result holds for all practically interesting cases when comparing Cp-1 splines with C- 1 (discontinuous) splines. When comparing Cp-1 splines with C splines our proof covers almost all cases for p≥ 3 , but we can not conclude anything for p= 2. The results are generalized to the approximation of functions in Hq+1(0 , 1) for q< p, to broken Sobolev spaces and to tensor product spaces

The boundary Riemann solver coming from the real vanishing viscosity approximation

We study a family of initial boundary value problems associated to mixed hyperbolic-parabolic systems: v^{\epsilon} _t + A (v^{\epsilon}, \epsilon v^{\epsilon}_x ) v^{\epsilon}_x = \epsilon B (v^{\epsilon} ) v^{\epsilon}_{xx} The conservative case is, in particular, included in the previous formulation. We suppose that the solutions $v^{\epsilon}$ to these problems converge to a unique limit. Also, it is assumed smallness of the total variation and other technical hypotheses and it is provided a complete characterization of the limit. The most interesting points are the following two. First, the boundary characteristic case is considered, i.e. one eigenvalue of $A$ can be $0$. Second, we take into account the possibility that $B$ is not invertible. To deal with this case, we take as hypotheses conditions that were introduced by Kawashima and Shizuta relying on physically meaningful examples. We also introduce a new condition of block linear degeneracy. We prove that, if it is not satisfied, then pathological behaviours may occur.Comment: 84 pages, 6 figures. Text changes in Sections 1 and 3.2.3. Added Section 3.1.2. Minor changes in other section

Keck Spectroscopy of Two Young Globular Clusters in the Merger Remnant NGC 3921

Low-resolution UV-to-visual spectra of two candidate globular clusters in the merger remnant NGC 3921 are presented. These two clusters of apparent magnitude V = 22.2 (Mv = -12.5) lie at projected distances of ~5 kpc from the center and move with halo-type radial velocities relative to the local galaxy background. Their spectra show strong Balmer absorption lines indicative of main-sequence turnoffs dominated by A-type stars. Comparisons with model-cluster spectra computed by Bruzual & Charlot and others yield cluster ages in the range of 200-530 Myr, and metallicities about solar to within a factor of three. Given their small half-light radii (Reff < 5 pc) and ages corresponding to ~100 core- crossing times, these clusters are gravitationally bound and, hence, indeed young globulars. Assuming that they had Chabrier-type initial mass functions, their estimated current masses are 2.3(+-0.1)x10^6 Msun and 1.5(+-0.1)x10^6 Msun, respectively, or roughly half the mass of omegaCen. Since NGC 3921 itself shows many signs of being a 0.7(+-0.3) Gyr old protoelliptical, these two young globulars of roughly solar metallicity and their many counterparts observed with the Hubble Space Telescope provide supporting evidence that, in the process of forming elliptical-like remnants, major mergers of gas-rich disks can also increase the number of metal-rich globular clusters. (Abridged)Comment: 22 pages, 6 figures, accepted for publication in AJ, July 200

Suppression of Fusarium moniforme by Streptomyces spp. isolates in relation to dose- response relationship

Suplemento. Edição do IX International Congress of Plant Pathology, 2008, Torino. Abstracts on invited and offered papers

Controle de Fusarium moniliforme em sementes de milho por actinomicetos.

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