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Search Results: 1 - 10 of 15956 matches for " Pedro Herranz "
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Compact Source Detection in Multichannel Microwave Surveys: From SZ Clusters to Polarized Sources
Diego Herranz,Francisco Argüeso,Pedro Carvalho
Advances in Astronomy , 2012, DOI: 10.1155/2012/410965
Abstract: We describe the state-of-the art status of multifrequency detection techniques for compact sources in microwave astronomy. From the simplest cases where the spectral behaviour is well known (i.e., thermal SZ clusters) to the more complex cases where there is little a priori information (i.e., polarized radio sources) we will review the main advances and the most recent results in the detection problem. 1. Introduction Extragalactic foregrounds play a crucial role in microwave astronomy, not only by their effect as contaminants of the Cosmic Microwave Background (CMB) but also by their own right as cosmological probes. Galaxies and galaxy clusters, if not properly identified and taken into account, can seriously affect the measurement of the CMB anisotropies angular power spectrum in temperature [1–3] and polarization [4, 5], CMB non-Gaussianity tests [6–12], and even the performance of component separation methods used for the study of Galactic foregrounds (on the other hand, the opposite is also true: foregrounds can affect the performance of compact source detection algorithms. In general, compact source detection algorithms find it easier to deal with diffuse foregrounds than diffuse component separation techniques to deal with compact sources, so the typical CMB analysis pipeline includes the detection of compact sources as a previous step to diffuse component separation) [13, 14]. On the other hand, galaxy and galaxy cluster surveys in the submm regime of the electromagnetic spectrum are powerful tools for cosmology [15–17]. This is the motivation of the considerable number of works on extragalactic foreground detection that have appeared in the literature on recent years. As opposed to Galactic foregrounds, that are typically extended as diffuse clouds over large areas of the sky, individual extragalactic objects appear as compact blobs that subtend very small angular scales. For this reason, both galaxies and galaxy clusters are often referred to as compact sources and their detection/separation is typically treated as a problem apart from the one posed by the separation of Galactic diffuse components. It is precisely the compactness of extragalactic sources that makes it possible to detect them against the fluctuations of the diffuse components (CMB included) in single-frequency (channel) settings. Most of the detection methods that have been proposed in the literature make use of this scale diversity. The well-known SExtractor package [18], for example, is particularly good at estimating and then subtracting the background at coarse scales and
Towards (3+1) gravity through Drinfel'd doubles with cosmological constant
Angel Ballesteros,Francisco J. Herranz,Pedro Naranjo
Physics , 2015, DOI: 10.1016/j.physletb.2015.04.041
Abstract: We present the generalisation to (3+1) dimensions of a quantum deformation of the (2+1) (Anti)-de Sitter and Poincar\'e Lie algebras that is compatible with the conditions imposed by the Chern-Simons formulation of (2+1) gravity. Since such compatibility is automatically fulfilled by deformations coming from Drinfel'd double structures, we believe said structures are worth being analysed also in the (3+1) scenario as a possible guiding principle towards the description of (3+1) gravity. To this aim, a canonical classical $r$-matrix arising from a Drinfel'd double structure for the three (3+1) Lorentzian algebras is obtained. This $r$-matrix turns out to be a twisted version of the one corresponding to the (3+1) $\kappa$-deformation, and the main properties of its associated noncommutative spacetime are analysed. In particular, it is shown that this new quantum spacetime is not isomorphic to the $\kappa$-Minkowski one, and that the isotropy of the quantum space coordinates can be preserved through a suitable change of basis of the quantum algebra generators. Throughout the paper the cosmological constant appears as an explicit parameter, thus allowing the (flat) Poincar\'e limit to be straightforwardly obtained.
From Lorentzian to Galilean (2+1) gravity: Drinfel'd doubles, quantisation and noncommutative spacetimes
Angel Ballesteros,Francisco J. Herranz,Pedro Naranjo
Physics , 2014, DOI: 10.1088/0264-9381/31/24/245013
Abstract: It is shown that the canonical classical $r$-matrix arising from the Drinfel'd double structure underlying the two-fold centrally extended (2+1) Galilean and Newton-Hooke Lie algebras (with either zero or non-zero cosmological constant $\Lambda$, respectively) originates as a well-defined non-relativistic contraction of a specific class of canonical $r$-matrices associated with the Drinfel'd double structure of the (2+1) (anti)-de Sitter Lie algebra. The full quantum group structure associated with such (2+1) Galilean and Newton-Hooke Drinfel'd doubles is presented, and the corresponding noncommutative spacetimes are shown to contain a commuting 'absolute time' coordinate ${\hat x}_0$ together with two noncommutative space coordinates $({\hat x}_1,{\hat x}_2)$, whose commutator is a function of the cosmological constant $\Lambda$ and of the (central) 'quantum time' coordinate ${\hat x}_0$. Thus, the Chern-Simons approach to Galilean (2+1) gravity can be consistently understood as the appropriate non-relativistic limit of the Lorentzian theory, and their associated quantum group symmetries (which do not fall into the family of so-called kappa-deformations) can also be derived from the (anti)-de Sitter quantum doubles through a well-defined quantum group contraction procedure.
Twisted (2+1) $κ$-AdS Algebra, Drinfel'd Doubles and Non-Commutative Spacetimes
ángel Ballesteros,Francisco J. Herranz,Catherine Meusburger,Pedro Naranjo
Physics , 2014, DOI: 10.3842/SIGMA.2014.052
Abstract: We construct the full quantum algebra, the corresponding Poisson-Lie structure and the associated quantum spacetime for a family of quantum deformations of the isometry algebras of the (2+1)-dimensional anti-de Sitter (AdS), de Sitter (dS) and Minkowski spaces. These deformations correspond to a Drinfel'd double structure on the isometry algebras that are motivated by their role in (2+1)-gravity. The construction includes the cosmological constant $\Lambda$ as a deformation parameter, which allows one to treat these cases in a common framework and to obtain a twisted version of both space- and time-like $\kappa$-AdS and dS quantum algebras; their flat limit $\Lambda\to 0$ leads to a twisted quantum Poincar\'e algebra. The resulting non-commutative spacetime is a nonlinear $\Lambda$-deformation of the $\kappa$-Minkowski one plus an additional contribution generated by the twist. For the AdS case, we relate this quantum deformation to two copies of the standard (Drinfel'd-Jimbo) quantum deformation of the Lorentz group in three dimensions, which allows one to determine the impact of the twist.
Lesiones purpúricas en dorso nasal, pabellones auriculares y dedos
Maldonado Cid,Paola; Sendagorta Cudós,Elena; Noguera Morel,Lucero; Herranz Pinto,Pedro;
Revista Clínica de Medicina de Familia , 2011, DOI: 10.4321/S1699-695X2011000300016
Abstract: we report a patient with purpuric lesions at acral sites. the differential diagnosis of this type of lesion includes a wide variety diseases, so every patient must be urgently/preferentially referred for a dermatologic evaluation. a complete study must be performed including a blood test with immunological parameters and a skin biopsy. in a very short time the lesions developed into the typical clinical form of discoid lupus, and responded favourably to treatment
Anal Carcinoma in an HIV-Infected Woman
Elena Sendagorta,Pedro Herranz,Héctor Guadalajara,Francisco Zamora
The Scientific World Journal , 2010, DOI: 10.1100/tsw.2010.92
Detection of spin torque magnetization dynamics through low frequency noise
Juan Pedro Cascales,David Herranz,Ursula Ebels,Jordan Katine,Farkhad G. Aliev
Physics , 2015, DOI: 10.1063/1.4927827
Abstract: We present a comparative study of high frequency dynamics and low frequency noise in elliptical magnetic tunnel junctions with lateral dimensions under 100 nm presenting current-switching phenomena. The analysis of the high frequency oscillation modes with respect to the current reveals the onset of a steady-state precession regime for negative bias currents above $J=10^7 A/cm^2$, when the magnetic field is applied along the easy axis of magnetization. By the study of low frequency noise for the same samples, we demonstrate the direct link between changes in the oscillation modes with the applied current and the normalised low frequency (1/f) noise as a function of the bias current. These findings prove that low frequency noise studies could be a simple and powerful technique to investigate spin-torque based magnetization dynamics.
Contribution of contrast enhanced sonography in the etiological diagnosis of focal splenic lesions Aportación de la ecografía contrastada en el diagnóstico etiológico de lesiones ocupantes de espacio esplénicas
Laura Casanova-Martínez,Eva Marín-Serrano,Marta Jaquotot-Herranz,Pedro Mora-Sanz
Revista Espa?ola de Enfermedades Digestivas , 2012,
Role of contrast-enhanced ultrasound in clinical staging of pancreatic cancer Papel de la ecografía contrastada en la estadificación clínica del cáncer de páncreas
Marta Jaquotot-Herranz,Eva Marín-Serrano,Laura Casanova-Martínez,Pedro Mora-Sanz
Revista Espa?ola de Enfermedades Digestivas , 2012,
Morfología ecográfica del ápex prostático: implicaciones en su disección durante la prostatectomía
Herranz Amo,F.;
Actas Urológicas Espa?olas , 2004, DOI: 10.4321/S0210-48062004000600001
Abstract: the prostatic apex can present various morphologies. myers, on the basis of prostatectomy specimens classified these into two main groups: prostates without an anterior dip (doughnunt shaped) and those with an anterior dip (croissant shaped). surgical duration for prostatectomy known as "apical dissection" must be altered depending on the morphology of the prostatic apex, to prevent incomplete resection of the gland. with transrectal ultrasound performed during transrectal biopsy, the morphology of the apex can be established in each gland. this would help us to plan dissection of the apex in each specific case, avoiding unwanted dissection of the posterior lip of the prostatic apex.
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