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Search Results: 1 - 10 of 13913 matches for " X. Castelló "
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The X-ray luminous galaxies optically classified as star forming are mostly narrow line Seyfert 1s
N. Castelló-Mor,X. Barcons,L. Ballo,F. J. Carrera,M. J. Ward,C. Jin
Physics , 2012, DOI: 10.1051/0004-6361/201118301
Abstract: We aim to characterize the nature of galaxies whose optical emission line diagnostics are consistent with star formation, but whose X-ray properties strongly point towards the presence of an AGN. Understanding these sources is of particular importance in assessing the completeness of AGN samples derived from large galaxy surveys, selected solely on the basis of their optical spectral properties.We construct a large sample of 211 NELGs, which have FWHMs Hb emission line <1200 km/s from the SDSS-DR7 galaxy spectroscopic catalogue, for which we are able to construct a classical diagnostic diagram, [OIII]/Hb versus [NII]/Ha (hence z<0.4), and that are also detected in the hard energy band and present in the 2XMM catalogue. This sample offers a large database by which to investigate potential mismatches between optical diagnostics and X-ray emission. Among these 211 objects, which based on our selection criteria are all at z<0.4, we find that 145 galaxies are diagnosed as AGNs, having 2-10 keV X-ray luminosities that span a wide range, from 10^40 erg/s to above 10^44 erg/s. Out of the remaining 66 galaxies, which are instead diagnosed as SF, we find a bimodal distribution in which 28 have X-ray luminosities in excess of 10^42 erg/s, large T (>1), and large X/O ratio (>0.1), while the rest are consistent with being simply SF galaxies. Those 28 galaxies exhibit the broadest Hb line FWHMs, from ~300 to 1200 km/s, and their X-ray spectrum is steeper than average and often displays a soft excess. We therefore conclude that the population of X-ray luminous NELGs with optical lines consistent with those of a starforming galaxy (which represent 19% of our whole sample) is largely dominated by NLS1s. The occurrence of such sources in the overall optically selected sample is small (<2%), hence the contamination of optically selected galaxies by NLS1s is very small.
Broad lifetime distributions for ordering dynamics in complex networks
R. Toivonen,X. Castelló,V. M. Eguíluz,J. Saram?ki,K. Kaski,M. San Miguel
Physics , 2008, DOI: 10.1103/PhysRevE.79.016109
Abstract: We search for conditions under which a characteristic time scale for ordering dynamics towards either of two absorbing states in a finite complex network of interactions does not exist. With this aim, we study random networks and networks with mesoscale community structure built up from randomly connected cliques. We find that large heterogeneity at the mesoscale level of the network appears to be a sufficient mechanism for the absence of a characteristic time for the dynamics. Such heterogeneity results in dynamical metastable states that survive at any time scale.
Modeling two-language competition dynamics
M. Patriarca,X. Castelló,J. R. Uriarte,V. M. Eguíluz,M. San Miguel
Computer Science , 2012, DOI: 10.1142/S0219525912500488
Abstract: During the last decade, much attention has been paid to language competition in the complex systems community, that is, how the fractions of speakers of several competing languages evolve in time. In this paper we review recent advances in this direction and focus on three aspects. First we consider the shift from two-state models to three state models that include the possibility of bilingual individuals. The understanding of the role played by bilingualism is essential in sociolinguistics. In particular, the question addressed is whether bilingualism facilitates the coexistence of languages. Second, we will analyze the effect of social interaction networks and physical barriers. Finally, we will show how to analyze the issue of bilingualism from a game theoretical perspective.
Dynamics of link states in complex networks: The case of a majority rule
J. Fernández-Gracia,X. Castelló,V. M. Eguíluz,M. San Miguel
Computer Science , 2012, DOI: 10.1103/PhysRevE.86.066113
Abstract: Motivated by the idea that some characteristics are specific to the relations between individuals and not of the individuals themselves, we study a prototype model for the dynamics of the states of the links in a fixed network of interacting units. Each link in the network can be in one of two equivalent states. A majority link-dynamics rule is implemented, so that in each dynamical step the state of a randomly chosen link is updated to the state of the majority of neighboring links. Nodes can be characterized by a link heterogeneity index, giving a measure of the likelihood of a node to have a link in one of the two states. We consider this link-dynamics model on fully connected networks, square lattices and Erd \"os-Renyi random networks. In each case we find and characterize a number of nontrivial asymptotic configurations, as well as some of the mechanisms leading to them and the time evolution of the link heterogeneity index distribution. For a fully connected network and random networks there is a broad distribution of possible asymptotic configurations. Most asymptotic configurations that result from link-dynamics have no counterpart under traditional node dynamics in the same topologies.
De la investigación sobre el proceso de composición a la ense?anza de la escritura
Revista signos , 2002, DOI: 10.4067/S0718-09342002005100011
Abstract: in the last twenty years, research on writing has changed from focusing almost exclusively on a cognitive analysis of the writing process to inquiring into the possibility and the need to teach this process (camps & castelló, 1996). this change in perspective has been gradual but definite, which has currently allowed teachers to have a knowledge corpus available in education. this, in turn, feeds new research and new ways to interpret the writing process. in this paper, our aim will be to analyze the main changes in the way how the writing process has been conceived during the last years and in the challenges these conceptions pose the teaching of writing.
Accessibility to university museums: A strategical objective
Edmon Castell
University Museums and Collections Journal , 2009,
Abstract: In the National University of Colombia there are currently 25 museums and collections including art, medicine, natural science, anthropology and history. Taken together, they comprise the largest, most diverse and most important museum in Colombia, and also the least known. The collections are the product of the conservation and research work of the university in the 141 years of its existence. In recent years, the National University of Colombia has not only become more aware of the importance of its cultural and scientific heritage, but also of the marginality of the work in the university museums. For that reason, in 2006 the university began to work on a Museums and Cultural Heritage Project to develop policies for the conservation, acquisition, documentation, research and communication of its own cultural heritage. The National University of Colombia hopes, through the development of a stronger, structured, ethical, responsible, efficient and representative project about Museums and Cultural Heritage to be better prepared for current challenges. In addition, the project hopes to generate a new landscape of accessibility to the museums and collections of the National University of Colombia. In short, the Museums and Cultural Heritage System of the National University of Colombia, through a ‘Museums portal’ located in a colonial building in Bogotá known as Claustro de San Agustín (Cloister of St. Augustine) seeks to highlight the cultural heritage of the university, and become, beyond the classrooms and research centers of the campus, an important reference for the meeting of teachers, students, citizens and other cultural and academic institutions.
El tractament de les construccions amb verb suport en els diccionaris monolingües i bilingües de l'alemany i el català [The treatment of support-verb constructions in monolingual and bilingual German and Catalan dictionaries]
Castell, Andreu
Zeitschrift für Katalanistik , 2011,
Abstract: Taking as a starting point a corpus based on the most representative grammars of the German language, the aim of this paper is to analyze the treatment of support verb constructions in monolingual and bilingual dictionaries of German and Catalan. More specifically, the analysis will focus on the number of support verb constructions in the corpus that appear in these dictionaries and how they are then represented in the entries dedicated to both the participating verbs and nouns.
De la investigación sobre el proceso de composición a la ense anza de la escritura
Montserrat Castelló
Revista Signos , 2002,
Abstract: En los últimos veinte a os la investigación sobre escritura ha pasado de centrarse casi exclusivamente en el análisis cognitivo del proceso de composición a preguntarse por la posibilidad y la necesidad de ense anza de este proceso (Camps y Castelló, 1996). El cambio de perspectiva ha sido gradual pero decidido y ello ha permitido que en la actualidad se disponga de un cierto corpus de conocimientos útiles para el ámbito educativo que, a su vez, alimentan nuevas investigaciones y nuevas formas de interpretar el proceso de composición. En este artículo nos centraremos en analizar los principales cambios que en los últimos a os han acaecido en la manera de concebir el proceso de composición y en los retos que esta concepción plantea a la ense anza de la escritura. In the last twenty years, research on writing has changed from focusing almost exclusively on a cognitive analysis of the writing process to inquiring into the possibility and the need to teach this process (Camps & Castelló, 1996). This change in perspective has been gradual but definite, which has currently allowed teachers to have a knowledge corpus available in education. This, in turn, feeds new research and new ways to interpret the writing process. In this paper, our aim will be to analyze the main changes in the way how the writing process has been conceived during the last years and in the challenges these conceptions pose the teaching of writing.
Adapting Building Design to Access by Individuals with Intellectual Disability
L Castell
Australasian Journal of Construction Economics and Building , 2012,
Abstract: Over the last 15 years, since introductionof the Disability Discrimination Act (DDA)(Commonwealth Government of Australia,1992), there has been much discussionabout the extent and nature of buildingaccess for the disabled, particularly inresponse to proposed revisions to theBuilding Code of Australia (BCA) and theintroduction of a Premises Standardcovering building access. Much of theargument which contributed to the twoyear delay in submitting a final version ofthese documents for government approvalrelated to the extent of access provisionsand the burden of cost. The final versionsubmitted to government by the AustralianBuilding Codes Board (ABCB) (notreleased publicly) appears to still containinconsistencies between the DDA and theBCA in several areas such as wayfindingand egress.In the debate preceding submission of thefinal version there appears to have beenlittle reference to access requirements forindividuals with intellectual disability (ID).This may be due to a general lack ofresearch on the topic. Consequently, thispaper uses a combination of theknowledge gained from a limited numberof previous wayfinding studies, literaturedescribing general problems faced bythose with ID and the author’s personalexperience observing others with ID tocreate a list of probable difficulties andsuggested solutions. The paperconcludes with a discussion about theassociated cost implications and benefitsin providing the required access.
Globalización, sociedad y política en la era de la Información
Castell Manuel
Bitácora Urbano-Territorial , 2011,
Abstract: Después de concluir mi libro La ciudad y las a masas, hace15 a os, empecé a sentir que había un extraordinario cambio multidimensional en todo el mundo. Desde luego cambio tecnológico; pero también reestructuración económica, que en parte adquiría la forma del denominado neoliberalismo, pero que iba más lejos que alcanzar las sociedades que he llamado estatistas – en ese entonces conocidas como sociedades de socialismo real-, comprometidas también en una reestructuración desde el nombre de perestroika. Ocurrió que la perestroika socialista fracasó, mientras que desde el punto de vista capitalista y sus intereses la perestroika capitalista funcionó –al menos para el capitalismo, aunque no tanto para la gente-, había también un cambio cultural profundo ligado a movimientos sociales culturales como el feminista en un sentido amplio, los movimientos urbanos y ecologístas. Es decir, había una serie de procesos históricos de cambio tecnológico, económico y cultural que interactuaban, aunque tenían origen independiente. En su conjunto estaban transformando el mapa político, intelectual e ideológico, sin que realmente supiéramos qué estaba pasando, en buena parte porque estábamos intentando analizarlos con categoría y datos obsoletos.
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