86,848 research outputs found

    Non trivial chiroptical responses: experimental and theoretical investigations

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    In the past few years, our two groups of research have been collaborating on a number of projects dealing with the assignment of the absolute configuration (AC) of complex chiral molecules of phar- macological interest in the disordered phase. [1] These studies have been mainly carried out by means of electronic circular dichroism (ECD) spectroscopy and quantum mechanical (QM) calculations at the den- sity functional theory (DFT) level of approximation. Particular attention has been payed to non-trivial chiroptical responses due to conformational flexibility and solvation. Beside these shared activities, some more specific research fields have been investigated too. In par- ticular, the Bologna group has performed studies concerning the hyphenation of enantioselective HPLC methods with detection systems based on ECD [2] and the characterization of biomolecular recognition phenomena between drugs and target or carrier macromolecules. [3] The Salerno group has developed some skills in vibrational circular dichroism (VCD) [4] and chiral NMR [5] spectroscopies, thanks to the availability of a VCD spectrometer and previous studies concerning the non-linear response of molecules exposed to radiation. [1] (a) C. Bertucci, M. Pistolozzi, D. Tedesco, R. Zanasi, R. Ruzziconi, A. M. Di Pietra, J. Chromatogr. A 2012, 1232, 128–133; (b) D. Tedesco, R. Zanasi, A. Guerrini, C. Bertucci, Chirality 2012, 24, 741–750; (c) F. Dong, J. Li, B. Chankvetadze, Y. Cheng, J. Xu, X. Liu, Y. Li, X. Chen, C. Bertucci, D. Tedesco, R. Zanasi, Y. Zheng, Environ. Sci. Technol. 2013, 47, 3386–3394; (d) W. J. Andrioli, R. Conti, M. J. Araújo, R. Zanasi, B. C. Cavalcanti, V. Manfrim, J. S. Toledo, D. Tedesco, M. O. de Moraes, C. Pessoa, A. K. Cruz, C. Bertucci, J. Sabino, D. N. P. Nanayakkara, M. T. Pupo, J. K. Bastos, J. Nat. Prod. 2014, 77, 70–78; (e) D. Tedesco, R. Zanasi, I. W. Wainer, C. Bertucci, J. Pharm. Biomed. Anal. 2014, 91, 92–96. [2] (a) C. Bertucci, D. Tedesco, J. Chromatogr. A 2012, 1269, 69–81; (b) D. Tedesco, A. M. Di Pietra, F. Rossi, M. Garagnani, E. Del Borrello, C. Bertucci, V. Andrisano, J. Pharm. Biomed. Anal. 2013, 81-82, 76–79. [3] (a) G. A. Ascoli, E. Domenici, C. Bertucci, Chirality 2006, 18, 667–679; (b) M. Pistolozzi, C. Bertucci, Chirality 2008, 20, 552–558; [4] (a) A. Lattanzi, A. Russo, P. Rizzo, G. Monaco, R. Zanasi, Chirality 2010, 22, E130–E135; (b) A. Massa, P. Rizzo, G. Monaco, R. Zanasi, Tetrahed. Lett. 2013, 54, 6242–6246. [5] (a) S. Pelloni, P. Lazzeretti, R. Zanasi, J. Chem. Theory Comput. 2007, 3, 1691–1698; (b) G. Monaco, R. Zanasi, Chirality 2011, 23, 752–755

    Crescere con un solo genitore: studenti nativi e immigrati a confronto.

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    Chi cresce con un solo genitore ha risultati scolastici peggiori, ma ci sono differenze a seconda del background migratorio? In un recente studio su studenti di scuola media in Italia, Raffaele Guetto, Francesca Zanasi, e Maria Carella, mostrano come gli studenti italiani siano più svantaggiati dall’assenza di un genitore rispetto a quelli immigrati. Lo studio ricerca i motivi della differenza nelle risorse a disposizione delle famiglie e nel motivo di assenza genitoriale

    A coalgebraic perspective on probabilistic logic programming

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    Probabilistic logic programming is increasingly important in artificial intelligence and related fields as a formalism to reason about uncertainty. It generalises logic programming with the possibility of annotating clauses with probabilities. This paper proposes a coalgebraic perspective on probabilistic logic programming. Programs are modelled as coalgebras for a certain functor F, and two semantics are given in terms of cofree coalgebras. First, the cofree F-coalgebra yields a semantics in terms of derivation trees. Second, by embedding F into another type G, as cofree G-coalgebra we obtain a “possible worlds” interpretation of programs, from which one may recover the usual distribution semantics of probabilistic logic programming

    Coalgebraic semantics for probabilistic logic programming

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    Probabilistic logic programming is increasingly important in artificial intelligence and related fields as a formalism to reason about uncertainty. It generalises logic programming with the possibility of annotating clauses with probabilities. This paper proposes a coalgebraic semantics on probabilistic logic programming. Programs are modelled as coalgebras for a certain functor F, and two semantics are given in terms of cofree coalgebras. First, the cofree F-coalgebra yields a semantics in terms of derivation trees. Second, by embedding F into another type G, as cofree G-coalgebra we obtain a 'possible worlds' interpretation of programs, from which one may recover the usual distribution semantics of probabilistic logic programming. Furthermore, we show that a similar approach can be used to provide a coalgebraic semantics to weighted logic programming

    The Cost of Compositionality A High-Performance Implementation of String Diagram Composition

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    String diagrams are an increasingly popular algebraic language for the analysis of graphical models of computations across different research fields. Whereas string diagrams have been thoroughly studied as semantic structures, much less attention has been given to their algorithmic properties, and efficient implementations of diagrammatic reasoning are almost an unexplored subject. This work intends to be a contribution in such a direction. We introduce a data structure representing string diagrams in terms of adjacency matrices. This encoding has the key advantage of providing simple and efficient algorithms for composition and tensor product of diagrams. We demonstrate its effectiveness by showing that the complexity of the two operations is linear in the size of string diagrams. Also, as our approach is based on basic linear algebraic operations, we can take advantage of heavily optimised implementations, which we use to measure performances of string diagrammatic operations via several benchmarks. © P. Wilson & F. Zanas

    Rewriting in Free Hypegraph Categories

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    We study rewriting for equational theories in the context of symmetric monoidal categories where there is a separable Frobenius monoid on each object. These categories, also called hypergraph categories, are increasingly relevant: Frobenius structures recently appeared in cross-disciplinary applications, including the study of quantum processes, dynamical systems and natural language processing. In this work we give a combinatorial characterisation of arrows of a free hypergraph category as cospans of labelled hypergraphs and establish a precise correspondence between rewriting modulo Frobenius structure on the one hand and double-pushout rewriting of hypergraphs on the other. This interpretation allows to use results on hypergraphs to ensure decidability of confluence for rewriting in a free hypergraph category. Our results generalise previous approaches where only categories generated by a single object (props) were considered

    Universal Constructions for (Co)Relations: categories, monoidal categories, and props

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    Calculi of string diagrams are increasingly used to present the syntax and algebraic structure of various families of circuits, including signal flow graphs, electrical circuits and quantum processes. In many such approaches, the semantic interpretation for diagrams is given in terms of relations or corelations (generalised equivalence relations) of some kind. In this paper we show how semantic categories of both relations and corelations can be characterised as colimits of simpler categories. This modular perspective is important as it simplifies the task of giving a complete axiomatisation for semantic equivalence of string diagrams. Moreover, our general result unifies various theorems that are independently found in literature and are relevant for program semantics, quantum computation and control theory
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