Osservazioni su due casi di poliploidia indotta in Vitis vinifera L. (cv. Barbera)

Vengono descritti gli aspetti citologici ed istologici di due viti cv. Barbera irraggiate con CO60 e present anti fenotipo poliploide.Le analisi compiute hanno riguardato il conteggio dei cromosomi negli apici radicali, l'osservazione degli strati epidermico e subepidermico delle gemme ibernanti, dei granuli pollinici, degli stomi, delle cellule dell'epidermide degli acini.Da tali osservazioni è emerso che un individuo è totalmente tetraploide, mentre il secondo è una chimera periclinale del tipo 2n-4n.Investigations on two cases of induced polyploidy in Vitis vinifera L. (cv. Barbera)The authors describe cytological and histological aspects of two grapevine plants, cv. Barbera, previously irradiated with CO60 and showing polyploid phenotype.The number of chromosomes in the root tip cells, the two first meristematic layers of wintering buds, the size of pollen grains, stornata, and epidermal cells of berries were investigated.The results show that one of them is a tetraploid grape, while the other was found to be a 2n-4n periclinal chimera

Binary black hole merger in the extreme mass ratio limit

We discuss the transition from quasi-circular inspiral to plunge of a system of two nonrotating black holes of masses $m_1$ and $m_2$ in the extreme mass ratio limit $m_1m_2\ll (m_1+m_2)^2$. In the spirit of the Effective One Body (EOB) approach to the general relativistic dynamics of binary systems, the dynamics of the two black hole system is represented in terms of an effective particle of mass $\mu\equiv m_1m_2/(m_1+m_2)$ moving in a (quasi-)Schwarzschild background of mass $M\equiv m_1+m_2$ and submitted to an ${\cal O}(\mu)$ radiation reaction force defined by Pad\'e resumming high-order Post-Newtonian results. We then complete this approach by numerically computing, \`a la Regge-Wheeler-Zerilli, the gravitational radiation emitted by such a particle. Several tests of the numerical procedure are presented. We focus on gravitational waveforms and the related energy and angular momentum losses. We view this work as a contribution to the matching between analytical and numerical methods within an EOB-type framework.Comment: 14 pages, six figures. Revised version. To appear in the CQG special issue based around New Frontiers in Numerical Relativity conference, Golm (Germany), July 17-21 200

Is symmetry identity?

Wigner found unreasonable the "effectiveness of mathematics in the natural sciences". But if the mathematics we use to describe nature is simply a coded expression of our experience then its effectiveness is quite reasonable. Its effectiveness is built into its design. We consider group theory, the logic of symmetry. We examine the premise that symmetry is identity; that group theory encodes our experience of identification. To decide whether group theory describes the world in such an elemental way we catalogue the detailed correspondence between elements of the physical world and elements of the formalism. Providing an unequivocal match between concept and mathematical statement completes the case. It makes effectiveness appear reasonable. The case that symmetry is identity is a strong one but it is not complete. The further validation required suggests that unexpected entities might be describable by the irreducible representations of group theory

An automatic email management approach using data mining techniques

Email mining provides solution to email overload problem by automatically placing emails into some meaningful and similar groups based on email subject and contents. Existing email mining systems such as BuzzTrack, do not consider the semantic similarity between email contents, and when large number of email messages are clustered to a single folder it retains the problem of email overload. The goal of this paper is to solve the problem of email overload through semantically structuring the user’s email by automatically organizing email in folders and sub-folders using data mining clustering technique and extracting important terms from created folders using Apriori-based method for folder identification. This paper proposes a system named AEMS for automatic folder and sub-folder creation and later indexing the created folders. For AEMS module, a novel approach named Semantic non-parametric K-Means++ clustering is proposed for folder creation. Experiments show the effectiveness and efficiency of the proposed techniques using large volumes of email datasets

Il nuovo volto dell'universo

Quale realtà indaga la più avanzata scienza odierna? Con quali strumenti concettuali opera? Dai contributi di alcuni fisici italiani emerge un'immagine del mondo radicalmente rinnovata. Petrillo, R. Rozzi, G. Sapelli, A. Savignano, L. Sicca, F. Silari, P. Toninelli, M. Vasta, G. Zanetti. mal di mare. Il velista che dispone di una imbarcazione progettata e equipaggiata secondo gli standard degli anni '90, con un'accurata preparazione, sarà in grado di unirsi alla schiera di navigatori famosi che sono sopravvissuti a condizioni ambientali proibitive