1435 research outputs found
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Sequential Pattern Mining with Temporal and Content Constraints
No full textA tool for extracting sequential patterns with temporal and content constraints from logs is presented. The heart of the tool is a new algorithm capable of handling temporal constraints and itemsets with multiple occurrences of the same item. Applications of the system are discussed in the context of monitoring logs registered by a platform supporting distributed processes, developed within the European project BRITE
Stereoselective entry into the D-GalNAc series starting from the D-Gal one: a new access to N-acetyl-D-galactosamine and derivatives thereof
No full textA new stereoselective preparation of N-aceyl-D-galactosamine (1b) starting from the known p-methoxyphenyl 3,4-O-isopropylidene-6-O-(1-methoxy-1-methylethyl)-b-D-galactopyranoside (10) is described using a simple strategy based on (a) epimerization at C-2 of 10 via oxidation–reduction to give the talo derivative 11, (b) amination with configurational inversion at C-2 of 11 via a SN2-type reaction on its 2- imidazylate, (c) anomeric deprotection of the p-methoxyphenyl beta-D-galactosamine glycoside 14, (d) complete deprotection. Applying the same protocol to 2,3:5,6:30,40-tri-O-isopropylidene-60-O-(1-methoxy- 1-methylethyl)-lactose dimethyl acetal (4), directly obtained through acetonation of lactose, the disaccharide beta-D-GalNAcp-(1?4)-D-Glcp (1a) was obtained with complete stereoselectivity in good (40%) overall yield from lactose
Hierarchical, model-based risk management of critical infrastructures
No full textSUMMARY Risk management is a process that includes several steps, from vulnerability analysis to the formulation of a risk mitigation plan that selects countermeasures to be adopted. With reference to an information infrastructure, we present a risk management strategy that considers a sequence of hierarchical models, each describing dependencies among infrastructure components. A dependency exists anytime a security-related attribute of a component depends upon the attributes of other components. We discuss how this notion supports the formal definition of risk mitigation plan and the evaluation of the infrastructure robustness. A hierarchical relation exists among models that are analyzed because each model increases the level of details of some components in a previous one. Since components and dependencies are modeled through a hypergraph, to increase the model detail level, some hypergraph nodes are replaced by more and more detailed hypergraphs. We show how critical information for the assessment can be automatically deduced from the hypergraph and define conditions that determine cases where a hierarchical decomposition simplifies the assessment. In these cases, the assessment has to analyze the hypergraph that replaces the component rather than applying again all the analyses to a more detailed, and hence larger, hypergraph. We also show how the proposed framework supports the definition of a risk mitigation plan and discuss some indicators of the overall infrastructure robustness. Lastly, the development of tools to support the assessment is discussed
Suffix tree characterization of maximal motifs in biological sequences
No full textSUMMARY: Finding motifs in biological sequences is one of the most intriguing problems for string algorithm designers due to, on the one hand, the numerous applications of this problem in molecular biology and, on the other hand, the challenging aspects of the computational problem. Indeed, when dealing with biological sequences it is necessary to work with approximations (that is, to identify fragments that are not necessarily identical, but just similar, according to a given similarity notion), and this complicates the problem. Existing algorithms run in time linear with respect to the input size. Nevertheless, the output size can be very large due to the approximation (namely exponential in the approximation degree). This often makes the output unreadable, as well as slowing down the inference itself. A high degree of redundancy has been detected in the set of motifs that satisfy traditional requirements, even for exact motifs. Moreover, it has been observed many times that only a subset of these motifs, namely the maximal motifs, could be enough to provide the information of all of them. In this paper, we aim at removing such redundancy. We extend some notions of maximality already defined for exact motifs to the case of approximate motifs with Hamming distance, and we give a characterization of maximal motifs on the suffix tree. Given that this data structure is used by a whole class of motif extraction tools, we show how these tools can be modified to include the maximality requirement without changing the asymptotical complexity
An experimental analysis of laser engraving on marble / Analisi sperimentale del processo di marcatura laser su marmo
No full textQuesto articolo affronta la caratterizzazione e ottimizzazione del processo di incisione di materiali lapidei tramite fascio laser attraverso un’analisi sperimentale. La finalità è trovare possibili relazioni tra parametri impostati per la lavorazione e parametri geometrici ricavati dai solchi. Per questo studio sono stati analizzati dei campioni di marmo Bianco di Carrara. Per mezzo di un profilometro ottico è stato possibile misurare il profilo trasversale del solco, caratterizzato in maniera oggettiva con alcune misure descritte nell’articolo, inclusi due parametri di qualità visiva. Attraverso un’analisi statistica è possibile indicare le impostazioni ottimali da settare in base al risultato desiderato: es. aumento della larghezza, profondità o livello di contrasto del solco. English: This article deals with characterizing and optimizing the process of engraving stone materials with a laser beam through experimental testing. The purpose of testing was to find possible relations between the parameters set for work and the geometric parameters gotten from the grooves. For this study we tested samples of White Carrara marble. By means of an optical profilometer it was possible to measure the cross section of the groove, objectively characterized by a number of measurements described in the article including two parameters of visual quality. Through statistical analysis it was possible to indicate optimal settings to use on the basis of the results desired; for example, increasing the width, depth or contrast level of the groove
Memorie filologiche in alcuni Fondi storici dell'Università di Pisa. La Biblioteca Silvio Pellegrini e la Collezione Giovanna Marroni
No full textNell'articolo si descrive il fondo librario appartenuto alla filologa Giovanna Marroni, allieva di Silvio Pellegrini. This article contains the description of Giovanna Marroni's personal library,who was one of Silvio Pellegrini's student and later a filology teacher at Pisa's university
Libertà, impero, diritto e pace: ideologia e pratica di potere a Marsiglia nel XIII secolo
No full textPartendo dalla constatazione della grande autonomia politica e amministrativa di Marsiglia nel periodo indicato e dei forti legami che la città stabilì con altre autonomie cittadine dell'area tirrenica, la relazione intende rileggere i documenti istituzionali di Marsiglia ( patti bilaterali, paci, alleanze, giuramenti ) cercando nelle parti introduttive ed esplicative traccia di eventuali prestiti ideologici, recuperi letterari e scambi di modelli tra l'Italia comunale e le città del sud della Francia
La Basilica di San Pietro al tempo di Giulio II e Leone X: l’impresa e la spesa nel dibattito contemporaneo
Get PDFRIASSUNTO L'articolo ricostruisce le fasi iniziali del progetto e del finanziamento della costruzione della nuova Basilica di San Pietro a Roma, nei pontificati di Giulio II e Leone X, evidenziando in un'appendice antologica gli interventi critici o favorevoli delle grandi personalità culturali, religiose e architettoniche del tempo.
SUMMARY This essay describes the project and the fund raising for the new Saint Peter's Basilica in Rome, during the papacy of Giulio II and Leone X. The great cost of the building and the granting of indulgences in return for contributions arose a strong debate among the most important men of culture, religious writers and architects of that time. The anthology includes the most famous perspectives on the problem
Thermodynamics of two flavor QCD from imaginary chemical potentials
No full textWe study QCD thermodynamics in presence of two independent imaginary chemical
potentials coupled to two degenerate flavors of staggered quarks. Analytic
continuation is used to determine non-linear susceptibilities, to test the
Hadron Resonance Gas (HRG) model below the zero density critical temperature,
Tc, and to determine the average phase factor of the fermion determinant.
Deviations from HRG predictions, of the order of a few percent, are clearly
visible for temperatures T > 0.95 Tc. The determination of non-linear
susceptibilities, using different interpolating functions for analytic
continuation, gives consistent results and in agreement with Taylor expansion
computations, apart from some systematic effects at or right above Tc. Results
for the average phase factor are compared with the predictions of Chiral
Perturbation Theory; below Tc we are able to distinguish the contribution of
different hadron states, which is positive (i.e. tends to mitigate the sign
problem) in the case of baryons
Thermal Control of a Dual Mode Parametric Sapphire Transducer
No full textWe propose a method to control the thermal stability of a sapphire dielectric
transducer made with two dielectric disks separated by a thin gap and
resonating in the whispering gallery (WG) modes of the electromagnetic field.
The simultaneous measurement of the frequencies of both a WGH mode and a WGE
mode allows one to discriminate the frequency shifts due to gap variations from
those due to temperature instability. A simple model, valid in quasi
equilibrium conditions, describes the frequency shift of the two modes in terms
of four tuning parameters. A procedure for the direct measurement of them is
presented