Error analysis for quadratic spline quasi-interpolants on non-uniform criss-cross triangulations of bounded rectangular domains

Given a non-uniform criss-cross partition of a rectangular domain $\Omega$, we analyse the error between a function $f$ defined on $\Omega$ and two types of $C^1$-quadratic spline quasi-interpolants (QIs) obtained as linear combinations of B-splines with discrete functionals as coefficients. The main novelties are the facts that supports of B-splines are contained in $\Omega$ and that data sites also lie inside or on the boundary of $\Omega$. Moreover, the infinity norms of these QIs are small and do not depend on the triangulation: as the two QIs are exact on quadratic polynomials, they give the optimal approximation order for smooth functions. Our analysis is done for $f$ and its partial derivatives of the first and second orders and a particular effort has been made in order to give the best possible error bounds in terms of the smoothness of $f$ and of the mesh ratios of the triangulation

Near-best C2C^2 quartic spline quasi-interpolants on type-6 tetrahedral partitions of bounded domains

In this paper, we present new quasi-interpolating spline schemes defined on 3D bounded domains, based on trivariate $C^2$ quartic box splines on type-6 tetrahedral partitions and with approximation order four. Such methods can be used for the reconstruction of gridded volume data. More precisely, we propose near-best quasi-interpolants, i.e. with coefficient functionals obtained by imposing the exactness of the quasi-interpolants on the space of polynomials of total degree three and minimizing an upper bound for their infinity norm. In case of bounded domains the main problem consists in the construction of the coefficient functionals associated with boundary generators (i.e. generators with supports not completely inside the domain), so that the functionals involve data points inside or on the boundary of the domain. We give norm and error estimates and we present some numerical tests, illustrating the approximation properties of the proposed quasi-interpolants, and comparisons with other known spline methods. Some applications with real world volume data are also provided.Comment: In the new version of the paper, we have done some minor revisions with respect to the previous version, CALCOLO, Published online: 10 October 201

Accurate Local Estimation of Geo-Coordinates for Social Media Posts

Associating geo-coordinates with the content of social media posts can enhance many existing applications and services and enable a host of new ones. Unfortunately, a majority of social media posts are not tagged with geo-coordinates. Even when location data is available, it may be inaccurate, very broad or sometimes fictitious. Contemporary location estimation approaches based on analyzing the content of these posts can identify only broad areas such as a city, which limits their usefulness. To address these shortcomings, this paper proposes a methodology to narrowly estimate the geo-coordinates of social media posts with high accuracy. The methodology relies solely on the content of these posts and prior knowledge of the wide geographical region from where the posts originate. An ensemble of language models, which are smoothed over non-overlapping sub-regions of a wider region, lie at the heart of the methodology. Experimental evaluation using a corpus of over half a million tweets from New York City shows that the approach, on an average, estimates locations of tweets to within just 2.15km of their actual positions.Comment: In Proceedings of the 26th International Conference on Software Engineering and Knowledge Engineering, pp. 642 - 647, 201

Curve network interpolation by C1C^1 quadratic B-spline surfaces

In this paper we investigate the problem of interpolating a B-spline curve network, in order to create a surface satisfying such a constraint and defined by blending functions spanning the space of bivariate $C^1$ quadratic splines on criss-cross triangulations. We prove the existence and uniqueness of the surface, providing a constructive algorithm for its generation. We also present numerical and graphical results and comparisons with other methods.Comment: With respect to the previous version, this version of the paper is improved. The results have been reorganized and it is more general since it deals with non uniform knot partitions. Accepted for publication in Computer Aided Geometric Design, October 201

Trayectorias de los estudios sobre Ciencia, Tecnología y Sociedad, y de la política científica y tecnológica en Ibero-América

Este artículo realiza un recorrido histórico por la política científica de los Estudios sobre Ciencia, Tecnología y Sociedad (ECTS) en el marco iberoamericano (fundamentalmente Argentina, Brasil y España). Este trayecto concluye con la existencia de una brecha entre la orientación de la Política Científica y Tecnológica (PCT) y los ECTS. A través del análisis aquí propuesto, se buscarán las razones de la mencionada fisura y se intentará sellarla, generando cursos de acción que modifiquen el carácter de las PCT.This article exposes a historical approach of both Science Policy (SP) and Science, Technology and Society Studies (STSS) in Spain and Iberoamerican countries, especially Brasil and Argentina. It points out a special divide between the guidelines of Science Policies and STS Studies. Reasons of this divide are critically analyzed in order to avoid it by means of certain actions for modifying Science and Technology Policies

Transcultural Writers and Transcultural Literature in the Age of Global Modernity

Peer reviewed article. In our rapidly globalising world, cultures, as well as societies and identities, tend to be more fluid, less irreducibly different and less 'territorially fixed' than in the past (Schulze-Engler 2007, p. 27). Especially now, when cosmopolitan issues and pluralistic sensibilities - driven by transnational and transcommunal experiences - tend to become more relevant. It is within this emerging social context that a new generation of mobile writers, on the move across cultural and national boundaries, has started expressing a "transcultural" sensibility and mode of being, fostered by "the process of self-distancing, self-estrangement, and self criticism of one's own cultural identities and assumptions" (Epstein 1999, p. 307). In this paper, I argue that the main element that distinguishes these early 'transcultural writers' from their precursors and/or 'cousin species' (migrant/exile/diasporic/postcolonial writers) - albeit all belonging to the wider 'genus' of 'the literature of mobility' - is their relaxed, neonomadic attitude when facing issues linked to identity, nationality, rootlessness and dislocation. An attitude that reflects itself also in their creative outputs, which can already be inscribed within the realm of transcultural literature, a literature able to transcend the borders of a single culture in its choice of topic, vision and scope, thus contributing to promote a wider global literary perspective (Pettersson 2006)

Transcription of brain natriuretic peptide and atrial natriuretic peptide genes in human tissues

We have compared the expression of atrial natriuretic peptide (ANP) and brain natriuretic peptide (BNP) genes in various human tissues using a quantitative polymerase chain reaction technique. Tissues of three human subjects, obtained at autopsy, were analyzed. BNP transcripts could be detected in the central nervous system, lung, thyroid, adrenal, kidney, spleen, small intestine, ovary, uterus, and striated muscle. ANP transcripts could also be demonstrated in various human extracardiac tissues including several endocrine organs. In all peripheral tissues, the level of both natriuretic peptide transcripts was approximately 1-2 orders of magnitude lower than in cardiac ventricular tissues. This distribution is in marked contrast to the much lower level of ANP and BNP transcripts present in extracardiac rat tissues (generally less than 1/1000 of ventricles). These data suggest differential expression of the two natriuretic peptide genes in cardiac and extracardiac tissues in man. Furthermore, the presence of local synthesis of ANP and BNP in various peripheral organs suggests paracrine and/or autocrine function of these natriuretic peptides

Transcription of Brain Natriuretic Peptide and Atria1 Natriuretic Peptide Genes in Human Tissues.

We have compared the expression of atria1 natriuretic peptide (ANP) and brain natriuretic peptide (BNP) genes in various human tissues using a quantitative polymerase chain reaction technique. Tissues of three human subjects, obtained at autopsy, were analyzed. BNP transcripts could be detected in the central nervous system, lung, thyroid, adrenal, kidney, spleen, small intestine, ovary, uterus, and striated muscle. ANP transcripts could also be demonstrated in various human extracardiac tissues including several endocrine organs. In all periphera1 tissues, the level of both natriuretic peptide transcripts was approximately l-2 orders of magnitude lower than in cardiac ventricular tissues. This distribution is in marked contrast to the much lower level of ANP and BNP transcripts present in extracardiac rat tissues (generally less than l/1000 of ventricles). These data suggest differential expression of the two natriuretic peptide genes in cardiac and extracardiac tissues in man. Furthermore, the presence of local synthesis of ANP and BNP in various peripheral organs su gests paracrine and/or autocrine function of these natriuretic peptides