1,720,983 research outputs found
Non-equilibrium densities of Nelson processes
No full textIn this paper we analyze the idea that arbitrary probability densities solutions of the classical evolution
equation associated by the Nelson stochastic mechanics to the quantum mechanics always relax in time toward the
quantum mechanical density jj derived from the Schrodinger equation The analysis of a few general propositions
and of some physical examples show that the choice of the Nelson stochastic ux is correct for a particular class
of quantum states but can not be adopted in general This indicates that the question of the time relaxation of
the solutions of the Kolmogorov equation associated to a quantum wave function toward the quantum densities is
physically meaningful even if a classical probabilistic model good for every quantum state is still not available A
few suggestion in this direction are nally discusse
Non-locality and entropic uncertainty relations in neutrino oscillations
Full text linkUsing the wave-packet approach to neutrino oscillations, we analyze quantum-memory-assisted entropic uncertainty relations and show that uncertainty and the non-local advantage of quantum coherence are anti-correlated. Furthermore, we explore the hierarchy among three different definitions of NAQC, those based on l1-norm, relative entropy and skew information coherence measures, and we find that the coherence content detected by the l1-norm-based NAQC overcomes the other two. The connection between QMA-EUR and NAQC could provide a better understanding of the physical meaning of the results so far obtained and suggest their extension to quantum field theory
La civiltà della vite. La cultura del vino in Italia dall'antichità all'età moderna.
No full textDalle origini protostoriche fino alla tarda antichità, al Medioevo e all'età moderna, attraverso fonti archeologiche, iconografiche, letterarie e dati archeobotanici, con le tappe fondamentali della diffusione e l'evidenza di un filone autoctono preesistente alla colonizzazione greca.
Il volume comprende aspetti spirituali ed etici sulle libagioni conviviali, cultuali e funerarie, un database con le testimonianze archeobotaniche e un'appendice con i vini più famosi dell'antichità.
Si rivolge anche a studiosi di archeologia, storia, letteratura, mitologia, arte e naturalmente ad appassionati di vino, soddisfacendo curiosità di ambito tecnologico-scientifico e avvicinando alla sensibilità antica e ai significati della produzione e del consumo presso le genti stanziate sul territorio italiano
Hierarchies of geometric entanglement
No full textWe introduce a class of generalized geometric measures of entanglement. For pure quantum states of N elementary subsystems, they are defined as the distances from the sets of K-separable states (K=2,...,N). The entire set of generalized geometric measures provides a quantification and hierarchical ordering of the different bipartite and multipartite components of the global geometric entanglement, and allows discrimination among the different contributions. The extended measures are applied to the study of entanglement in different classes of N-qubit pure states. These classes include W and Greenberger-Horne-Zeilinger (GHZ) states, and their symmetric superpositions; symmetric multimagnon states; cluster states; and, finally, asymmetric generalized W-like superposition states. We discuss in detail a general method for the explicit evaluation of the multipartite components of geometric entanglement, and we show that the entire set of geometric measures establishes an ordering among the different types of bipartite and multipartite entanglement. In particular, it determines a consistent hierarchy between GHZ and W states, clarifying the original result of Wei and Goldbart that W states possess a larger global entanglement than GHZ states. Furthermore, we show that all multipartite components of geometric entanglement in symmetric states obey a property of self-similarity and scale invariance with the total number of qubits and the number of qubits per party
Characterization of ground state entanglement by single-qubit operations and excitation energies
No full text
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
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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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