1,721,004 research outputs found
Going 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
Simulating Metal Complex Formation and Ligand Exchange: Unraveling the Interplay between Entropy, Kinetics, and Mechanisms on the Chelate Effect
Full text linkMetal coordination is ubiquitous in Nature and central in many applications, ranging from nanotechnology to catalysis and environmental chemistry. Complex formation results from the subtle interplay between different thermodynamic, kinetic, and mechanistic contributions, which remain largely elusive to standard experimental methodologies and challenging for typical modeling approaches. Here, considering some prototypical metal complexes between Cd(II) and Ni(II) with various amine ligands, we present a comprehensive atomistic-level description of their chemical equilibrium, complex formation, and ligand exchange dynamics in aqueous solution, providing an excellent agreement with available association constants and formation rates spanning several orders of magnitude. This is achieved through an effective molecular simulation approach that combines finely tuned interatomic potentials with state-of-the-art enhanced sampling and kinetics techniques. Worthy of note, the nature of the chelate effect, a fundamental concept in coordination chemistry, is fully unravelled through the comparative analysis of the ligand binding reactions of monodentate and bidentate ligands in octahedral complexes. Results provide a complete picture illustrating all the concurrent contributions to this phenomenon, such as entropy, dissociation rates, and ligand binding mechanisms, in some cases contradicting previously held beliefs. This study represents a step forward for the in silico design and applications of coordination complex systems
La tossicologie neuro-comportamental dans l'etude des effets de "faibles doses": actuelles problematiques
No full textCalculated electron affinities and redox E° values of polypyridinic derivatives
No full textQuantum mechanical based ab-initio calculations are used to compute one-electron electrochemical standard reduction potentials, E-0, for a set of 12 polypyridinic derivatives (plus nitrobenzene and benzophenone as reference compounds) in dimethylformamide solution. Linear relationships between theoretical predictions and experimental data are constructed and provide a mean unsigned error of about 0.19 V. It is shown that the theoretical approach allows us also to discuss structural features related to the electron transfer process, like conformational changes found between the neutral and radical anion species (for instance, in the case of 4-4 ́dipyridyl a variation is found from 36degrees to almost zero of the ring-ring dihedral angle and a shortening of the single C-C bond when passing from the neutral to the radical anion). Also the weight of different terms (mainly: electron affinity, solvation Gibbs energies, DeltaG(0) of the 1/2 H-2(g), H-aq(+) + e(-) half-cell reaction) leading to the determination of E-0 is assessed on a quantitative basis
Procedimento ed apparato per la valutazione della durazza e per la selezione di prodotti orto-frutticoli
No full textIl brevetto descrive un procedimento ed un apparato per la valutazione della durezza e per la selezione di prodotti orto-frutticol
GAIL: Geometry-aware Automatic Image Localization
No full textThe access and integration of the massive amount of information, that can be provided by the web, can be of great help in a number of fields, including tourism and advertising of artistic sites. A "virtual visit" of a place can be a valuable experience before, during and after the experience on-site. For this reason, the contribution from the public could be merged to provide a realistic and immersive visit of known places. We propose an automatic image localization system, which is able to recognize the site that has been framed, and calibrate it on a pre-existing 3D representation. The system is characterized by very high accuracy and it is able to validate, in a completely unsupervised manner, the result of the localization. Given an unlocalized image, the system selects a relevant set of pre-localized images, performs a Structure from Motion partial reconstruction of this set and then obtain an accurate camera calibration of the image with respect to the model by minimizing distances between projections on the model surface of corresponding image features. The accuracy reached is enough to seamlessly view the input image correctly super-imposed in the 3D scene
Applicazione di un metodo integrato per la valutazione dei fattori di rischio stress-correlati nel settore sanitario
No full textVariations 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
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