1,720,957 research outputs found
Multimessenger astrophysics: When gravitational waves meet high energy neutrinos
No full textWith recent development of experimental techniques that have opened new windows of observation of the cosmic radiation in all its components, multi-messenger astronomy is entering an exciting era. Many astrophysical sources and cataclysmic cosmic events with burst activity can be plausible sources of concomitant gravitational waves (GWs) and high-energy neutrinos (HENs). Such messengers could reveal hidden and new sources that are not observed by conventional photon astronomy, in particular at high energy. Requiring consistency between GW and HEN detection channels enables new searches and a detection would yield significant additional information about the common source. We present the results of the first search for gravitational wave bursts associated with high energy neutrino triggers, detected by the underwater neutrino telescope ANTARES in its 5 line configuration, during the fifth LIGO science run and first Virgo science run. No evidence for coincident events was found. We place a lower limit on the distance to GW sources associated with every HEN trigger. We are able to rule out the existence of coalescing binary neutron star systems and black hole-neutron star systems up to distances that are typically 5 Mpc and 10 Mpc respectively. © 2013 Elsevier B.V. All rights reserved
Design and Development of an acoustic positioning system for a cubic kilometre underwater neutrino telescope
Full text linkEn los últimos años los telescopios submarinos de neutrinos han cobrado una mayor importancia ya que consisten en un nuevo y único instrumento para observar el Universo. Los neutrinos son partículas sin carga e interactúan muy débilmente con la materia que les rodean, pueden escaparse fácilmente de la fuente que los ha producidos y llegar a La Tierra sin ser desviada por los campo magnético y sin interactuar con otras partículas. Esto implica que los neutrinos pueden traer informaciones astrofísicas que otros mensajeros no pueden aportar y abrir una potencial ventana hacia el Universo. Por otro lado, su baja interacción con la materia impone la necesidad de construir un detector de grandes dimensiones del orden de 1 km3 utilizando volumen de agua o hielo y con muchos sensores ópticos para detectar esta interacción de neutrino de alta energía. Un método para detectar neutrinos es a través de la luz Cherenkov emitida por el muon generado después de una interacción de neutrino. Esta partícula, al atravesar el detector con una velocidad superior a la luz en el medio, genera una débil luz azulada llamada radiación de Cherenkov que es detectada por una red de sensores ópticos (fotomultiplicadores). El tiempo de llegada de la luz a los fotomultiplicadores puede ser utilizado para reconstruir la traza del muon y consecuentemente del neutrino que lo ha producido. La precisión en la reconstrucción de la traza del muon depende de la precisión en la medida del tiempo de llegada de la luz y en la precisión en de la posición de los sensores ópticos en el detector. Por esta razón, en telescopios submarinos es necesario un sistema de posicionamiento acústico (APS) capaz de monitorizar el movimiento de los sensores ópticos con una precisión de ~10 cm. Los estudios realizados están enmarcados dentro de las actividades de calibración de posicionamiento acústico en dos colaboraciones europeas para el diseño, construcción y operación de telescopios submarinos de neutrinos en el MediterLarosa ., G. (2012). Design and Development of an acoustic positioning system for a cubic kilometre underwater neutrino telescope [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/16877Palanci
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
