1,721,210 research outputs found
Fondazioni superficiali: osservazioni dall'analisi di case histories - General Lecture
No full textLe fondazioni superficiali costituiscono la tipologia più semplice ed antica di fondazione. Ciononostante, gli approcci di calcolo utilizzati nella pratica risentono di incertezze e limiti che si riflettono, ad esempio, nella valutazione della capacità portante a breve termine per fondazioni su argille e nella stima dei cedimenti per quelle in sabbie, anche se sottoposte a condizioni semplici di carico; le incertezze aumentano quando condizioni più complesse devono essere considerate. Tali aspetti spiegano l'accresciuto interesse di ricerca teorica e sperimentale sull'argomento, cui si sta assistendo negli ultimi anni. L'osservazione e l'analisi di casi studio ben documentati aiuta ad identificare, ed almeno in parte a chiarire, alcuni degli aspetti che possono dar luogo alle citate fonti di incertezza. Nel caso delle fondazioni superficiali i casi studio disponibili (aventi caratteristiche esaustive per tali analisi) non sono numerosi e sono prevalentemente riferiti a fondazioni sottoposte a carichi verticali e centrati. A questi si è fatto riferimento nella relazione, dando enfasi alla qualità delle informazioni ottenibili dai prescelti case histories e rivolgendo particolare attenzione a metodi di calcolo convenzionali. Le indicazioni ottenibili possono essere comunque di particolare utilità anche in relazione all'analisi critica dei risultati forniti da approcci più sofisticat
The rotational-conformational distribution of 2,2'-bithienyl in liquid crystals
No full textWe have investigated the distribution of conformations and orientations for a simple internal rotor molecule, 2,2'-bithienyl dissolved in liquid crystal solvents. by re-analysing published proton dipolar coupling data with the maximum entropy internal order method (MEIO). We show that detailed, model independent, conformational information can be obtained when data of sufficiently high quality are available. We also propose a novel and convenient representation method for the orientational-conformational coupling
Maximum entropy internal order approach to the study of intramolecular rotations in liquid crystals
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The conformations of alkyl chains in fluids. A maximum entropy approach
Full text linkWe present a maximum entropy internal order method for analyzing chain conformations in liquid crystalline solutions. We show how prior knowledge of the conformational distribution can be taken into account and apply the method to the determination of the conformation of n-alkanes in liquid crystals without invoking molecular field or other approximate theoretical models
A new maximum entropy conformational analysis of biphenyl in liquid crystal solution
No full textWe use the maximum entropy internal order (MEIO) method to reanalyze published (1)HNMR dipolar couplings for biphenyl dissolved in nematic solvents allowing for geometry variations with dihedral angle phi. We find that all present experimental data are consistent with similar conformational distributions with a maximum at phi = 34 - 35 degrees. Little rotational-conformational coupling has been found
A Multi Technique Maximum Entropy approach to the determination of the orientation and conformation of flexible molecules in solution
Full text linkWe present a maximum entropy method that allows the simultaneous analysis of different types of experimental data in order to obtain conformational information on flexible molecules in solution. We consider various NMR observables (dipolar, quadrupolar, J-couplings, nuclear Overhauser enhancements), and dielectric and neutron scattering techniques, and we express them using a common formalism in terms of orientational-conformational order parameters. We then show how these observables can be inverted in structural information allowing for continuous or discrete internal degrees of freedom and for any available prior information. We demonstrate the potentialities of the method on simulated (HNMR)-H-1, (HNMR)-H-2 and dielectric data for some terminally halogenated alkyl chains and show the improvement in conformational analysis obtained by simultaneously analyzing different and complementary data sets. (C) 1998 American Institute of Physics
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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