AMS Acta
(7,934 recursos)
Repository of the University of Bologna.

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Mostrando recursos 221 - 240 de 301

221.
ON THE CHARACTERISTIC DIRECTION OF REAL HYPERSURFACES IN C^(N+1) AND A SYMMETRY RESULT - Martino, Vittorio; Montanari, Annamaria
In this paper we show the following property of a non
Levi flat real hypersurface in C^(n+1): if the unit characteristic
direction T is a geodesic, then it is an eigenvector of the second
fundamental form and the relative eigenvalue is constant. As an
application we prove a symmetry result, of Alexandrov type, for
compact hypersurfaces in C^(n+1) with positive constant Levi mean
curvature.

222.
INTEGRAL FORMULAS FOR A CLASS OF CURVATURE PDE'S AND APPLICATIONS TO ISOPERIMETRIC INEQUALITIES AND TO SYMMETRY PROBLEMS - Martino, Vittorio; Montanari, Annamaria
We prove integral formulas for closed hypersurfaces in C^(n+1); which
furnish a relation between elementary symmetric functions in the eigenvalues of
the complex Hessian matrix of the defining function and the Levi curvatures of
the hypersurface. Then we follow the Reilly approach to prove an isoperimetric
inequality. As an application, we obtain the "Soap Bubble Theorem" for star-
shaped domains with positive and constant Levi curvatures bounding the classical
mean curvature from above.

223.
Self-evaluation test for student guidance: the case of the University of Bologna - Matteucci, Mariagiulia; Mignani, Stefania; Ricci, Roberto
In this work, the theme of student guidance in the university context is outlined. In order to introduce the competence evaluation for student guidance, a new guidance project based on self-evaluation tests of the University of Bologna (Italy) is presented. In the paper, the issues of item specification and test calibration are explored, with reference to item response theory models. Models are for multiple-choice and binary items and they assume that a single ability is responsible for the student performance in the test. The test calibration is conducted for the Statistics Faculty and the results are discussed, together with the...

224.
Adverb use in EFL student writing - Philip, Gill
Adverbs, especially those occurring in adverb+adjective collocations, play a central role in the language that advanced learners are expected to produce in their argumentative writing. However submodifying adverbs of degree such as ‘closely’, ‘deeply’, ‘strongly’ and ‘widely’ have been identified as being problematic for learners of English: Italian learners over-use very and really to the virtual exclusion of any other adverb (Philip 2007). This situation is due in part to the EFL curriculum, but monolingual and bilingual learner’s dictionaries appear to do little to address the issue. This contribution examines the treatment of lexical adverbs of degree in the five...

225.
Metaphorical Keyness in Specialised Corpora - Philip, Gill
What is more important in text: the topical content, or the manner in which topical content is presented? While statistically-generated key words tell us about a text’s content, the inter-relation between these words and the message of the text can be difficult to ascertain. One method of doing so is to observe the inter-relation of key words with evaluative language: in this case, metaphor. Metaphors are notoriously difficult to locate in corpora, but this paper sets out a method for their semi-automatic identification, and demonstrates how their interaction with keywords is both systematic and pervasive. Studying the interaction of key...

226.
Review of Hoey (2005)Lexical Priming - Philip, Gill
Book review of Hoey (2005) Lexical Priming. Describes and discusses presentation of contents and the implications of this novel approach to linguiatic theory.

227.
Idioms - Philip, Gill
Encyclopedia entry for "Idioms"

229.
“…and I dropped my jaw with fear”: The role of corpora in teaching phraseology - Philip, Gill
How can the effects of corpora on the language learning process be effectively assessed? This is an old question which is, however, just as important now as it was ten or twenty years ago. Does corpus use aid students in a measurable way? How does corpus use affect students’ subsequent language use? Is there a marked qualitative difference between the work of students who make use of corpora in their studies and those who do not? Does corpus use necessarily lead to an improvement in students’ language production?
This research reports an ongoing study into phraseological production in advanced learner writing...

230.
Which RPI-norms are the supremum of standard RPI-norms? - Baggio, Silvano
We settle some open problems regarding RPI-norms, i.e. norms (on a convenient subspace of differentiable real functions) that are invariant under differentiable reparametrizations. More precisely, we clarify some key points on how RPI-norms can be approximated using standard RPI-norms. We first prove that the sum of two standard RPI-norms is the supremum of a set of standard RPI-norms. This allows us to study a class of RPI-norms that can be expressed as the sup of standard ones. Finally, we give a positive answer to an open question on the existence of RPI-norms that are not the sup of standard RPI-norms.

232.
Bounds on short cylinders and uniqueness results for degenerate Kolmogorov equation - Cinti, Chiara; Polidoro, Sergio
We consider the Cauchy problem for hypoelliptic Kolmogorov equations in both divergence and non divergence form. We prove that, if |u(x,t)| < M exp(a(t^{-\beta}+|x|^2)) for some positive constants a, M, \beta in ]0,1[ and u(x,0) = 0, then u(x,t) = 0 for positive t. The proof of the main result is based on some previous uniqueness result and on the application of some estimates in short cylinders, first introduced by Safonov in the study of uniformly parabolic operators.

233.
Very Strongly Constrained Problems: An Ant Colony Optimization Approach - Maniezzo, V.; Roffilli, M.
Ant Colony Optimization (ACO) is a class of metaheuristic algorithms sharing the common approach of constructing a solution on the basis of information provided both by a standard constructive heuristic and by previously constructed solutions. This paper is composed of three parts. The first one frames ACO in current trends of research on metaheuristics for combinatorial optimization. The second outlines current research within the ACO community, reporting recent results obtained on different problems, while the third part focuses on a particular research line, named ANTS, providing some details on the algorithm and presenting results recently obtained on a prototypical strongly...

234.
Dai registri amministrativi ai sistemi informativi integrati per cooperative sociali ed aziende di terzo settore - Note da un progetto - Travaglini, Claudio
La situazione attuale dei registri e degli albi della cooperazione sociale e dei complessivi registri ed albi delle organizzazioni di terzo settore nel nostro territorio potrebbe essere sinteticamente descritta come “molti registri, poche informazioni e pochi controlli” in quanto caratterizzata dalla presenza di adempimenti amministrativi e raccolta di dati in gran parte asistematici ed a cui spesso non corrisponde la costruzione di un quadro informativo né la conduzione di una incisiva attività di controllo su questi enti.
La macro fase 4 “Directory delle cooperative sociali” del progetto Spring-Out condotta dal Polo Scientifico-Didattico di Rimini dell’università di Bologna si caratterizza come un...

236.
Ideals of varieties parameterized by certain symmetric tensors - Bernardi, A.
The ideal of a Segre variety is generated by the 2-minors of a generic hypermatrix of indeterminates. We extend this result to the case of SegreVeronese varieties. The main tool is the concept of “weak generic hypermatrix” which allows us to treat also the case of projection of Veronese surfaces from a set of generic points and of Veronese varieties from a Cohen-Macaulay subvariety of codimension 2.

237.
Social Banking in Practice: an Italian Case for Corporate Social
Responsibility in Banking - Lamandini, Marco; Steiner, Ilan
The paper introduces an important development in the area of corporate social responsibility in the banking sector, which has recently been accomplished in Italy. A new Italian bank (“Prossima s.p.a.”), incorporated in May 2007, articulates in its articles of association a number of innovative legal provisions that underscore its socially responsible features. To this end, deviation from profit maximization as a single corporate objective and formation of a designated organ (Committee) to guide the board of directors and set the framework for social banking are a landmark in terms of social banking and corporate governance. These provisions balance between shareholders...

238.
Equity markets, market efficiency and contestability of control in a trans-Atlantic perspective. - Lamandini, Marco
The article offers a comparative overview of some of the legal determinants affecting the cross-border market for corporate control in a trans-Atlantic perspective, in the wake of directive 2004/25/EC and its implementation by Member States as well as of recent decisions of both the European Court of Justice and the Commission concerning “golden shares” and other protectionist measures adopted by Member States to insulate national champions from the market for corporate control. The article questions whether national (final) ownership really meets the needs of the national community at large, thereby complying with a public interest test, or rather simply meets...

240.
La rocambolesca sopravvivenza del figliastro dell'Amfiparnaso: cronistoria di una caccia al testo - Merizzi, Gianmario
Il testo musicale dello Studio dilettevole di Adriano Banchieri, riduzione a tre voci dell'Amfiparnaso di Orazio Vecchi, viene finalmente completato grazie al contenuto di un'antologia tedesca del 1624 il cui unico esemplare, dato per disperso dopo la Seconda guerra mondiale, è ora conservato nella Biblioteka Jagiellonska di Cracovia.
Va sottolineato come nel corso della ricerca i dati offerti dai repertori bibliografici musicali correnti si siano rivelati inaffidabili e assai scarsamente aggiornati.