1,721,099 research outputs found
Fundamental bound for time measurements and minimum uncertainty clocks
Full text linkWe present a simple argument leading to a fundamental minimum uncertainty in the determination
of times. It only relies in the uncertainty principle and time dilation in a gravitational field. It implies
any attempt to measure times will have a fundamental level of uncertainty. Implications are briefly
outlined
Physical requirements for models of consciousness
Full text linkConsciousness presents a series of characteristics that have been observed through- out the years: unity, continuity, richness and robustness are some of them. It manifests itself in regions of the brain capable of processing a huge quantity of integrated information with a level of neural activity close to criticality. We argue that the physics of consciousness cannot be exclusively based on classical physics. Consciousness unity cannot be explained classically as the classical properties are always Humean like a mosaic. One needs an entangled quantum system that can at least satisfy part of the functions of a quantum computer to allow to generate an inner aspect with the unity of consciousness and to couple with a classical system that gives it simultaneous access to preprocessed information at the neural level and to produce events that generate neural firings
Loop Quantum Black Hole Extensions Within the Improved Dynamics
Full text linkWe continue our investigation of an improved quantization scheme for spherically symmetric loop quantum gravity. We find that in the region where the black hole singularity appears in the classical theory, the quantum theory contains semi-classical states that approximate general relativity coupled to an effective anisotropic fluid. The singularity is eliminated and the space-time can be continued into a white hole space-time. This is similar to previously considered scenarios based on a loop quantum gravity quantization
A first course in loop quantum gravity [book review]
No full textGAMBINI, Rodolfo, "A first course in loop quantum gravity". Oxford University Press, 2011. ISBN 9780199590759Depto. de Análisis Matemático y Matemática AplicadaFac. de Ciencias MatemáticasInstituto de Matemática Interdisciplinar (IMI)pu
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
A covariant polymerized scalar field in loop quantum gravity
Full text linkWe propose a new polymerization scheme for scalar fields coupled to gravity.
It has the advantage of being a (non-bijective) canonical transformation of the
fields and therefore ensures the covariance of the theory. We study it in
detail in spherically symmetric situations and compare to other approaches.Comment: 7 pages, RevTex, 1 figure, final submitted version to the Special
Issue Loop Quantum Gravity: A Themed Issue in Honor of Prof. Abhay Ashteka
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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