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Search Results: 1 - 10 of 9296 matches for " Julio Guerrero "
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Apuntes éticos sobre el ejercicio de la medicina en prisión Ethical notes on the practice of medicine in prison
Julio García Guerrero
Revista Espa?ola de Sanidad Penitenciaria , 2009,
Abstract:
Integración de la sanidad penitenciaria: un reto no tan decididamente asumido por muchos Integration of Prison Health Care
Julio García Guerrero
Revista Espa?ola de Sanidad Penitenciaria , 2011,
Abstract:
Wavelet Transform on the Circle and the Real Line: A Unified Group-Theoretical Treatment
Manuel Calixto,Julio Guerrero
Physics , 2004,
Abstract: We present a unified group-theoretical derivation of the Continuous Wavelet Transform (CWT) on the circle $\mathbb S^1$ and the real line $\mathbb{R}$, following the general formalism of Coherent States (CS) associated to unitary square integrable (modulo a subgroup, possibly) representations of the group $SL(2,\mathbb{R})$. A general procedure for obtaining unitary representations of a group $G$ of affine transformations on a space of signals $L^2(X,dx)$ is described, relating carrier spaces $X$ to (first or higher-order) ``polarization subalgebras'' ${\cal P}_X$. We also provide explicit admissibility and continuous frame conditions for wavelets on $\mathbb S^1$ and discuss the Euclidean limit in terms of group contraction.
Fast and Robust Fixed-Rank Matrix Recovery
German Ros,Julio Guerrero
Computer Science , 2015,
Abstract: We address the problem of efficient sparse fixed-rank (S-FR) matrix decomposition, i.e., splitting a corrupted matrix $M$ into an uncorrupted matrix $L$ of rank $r$ and a sparse matrix of outliers $S$. Fixed-rank constraints are usually imposed by the physical restrictions of the system under study. Here we propose a method to perform accurate and very efficient S-FR decomposition that is more suitable for large-scale problems than existing approaches. Our method is a grateful combination of geometrical and algebraical techniques, which avoids the bottleneck caused by the Truncated SVD (TSVD). Instead, a polar factorization is used to exploit the manifold structure of fixed-rank problems as the product of two Stiefel and an SPD manifold, leading to a better convergence and stability. Then, closed-form projectors help to speed up each iteration of the method. We introduce a novel and fast projector for the $\text{SPD}$ manifold and a proof of its validity. Further acceleration is achieved using a Nystrom scheme. Extensive experiments with synthetic and real data in the context of robust photometric stereo and spectral clustering show that our proposals outperform the state of the art.
Quantization of the Linearized Kepler Problem
Julio Guerrero,Jose Miguel Perez
Mathematics , 2003,
Abstract: The linearized Kepler problem is considered, as obtained from the Kustaanheimo-Stiefel (K-S)transformation, both for negative and positive energies. The symmetry group for the Kepler problem turns out to be SU(2,2). For negative energies, the Hamiltonian of Kepler problem can be realized as the sum of the energies of four harmonic oscillator with the same frequency, with a certain constrain. For positive energies, it can be realized as the sum of the energies of four repulsive oscillator with the same (imaginary) frequency, with the same constrain. The quantization for the two cases, negative and positive energies is considered, using group theoretical techniques and constrains. The case of zero energy is also discussed.
Nephritic syndrome associated to skin infection, hepatitis A, and pneumonia: a case report
Barrios,Emil Julio; Guerrero,Gustavo Adolfo;
Colombia Médica , 2010,
Abstract: introduction: glomerulonephritis is the most common cause of acute and chronic renal disease. the prototype of acute glomerulonephritis is acute post-infectious glomerulonephritis. recently, increased cases of glomerulopathy have been associated with bacterial, viral, and other infections. acute nephritic syndrome is part of glomerulonephritis with an acute beginning, characterized by hematuria, hypertension, edema, and oliguria due to the reduction of glomerular filtration reflected in an increase of nitrogen compounds. development: this paper shows a male infant at 2 years and 7 months of age with nephritic syndrome associated to a skin infection, pneumonia, and hepatitis a virus infection. conclusion: acute glomerulonephritis may be associated to streptococcus or another coincidental infection. children with skin infection, hepatitis a, or pneumonia who reveal abnormal urinalysis, hypertension, azotemia, or oliguria should be evaluated for concomitant glomerulonephritis.
Nephritic syndrome associated to skin infection, hepatitis A, and pneumonia: a case report
Emil Julio Barrios,Gustavo Adolfo Guerrero
Colombia Médica , 2010,
Abstract: Introduction: Glomerulonephritis is the most common cause of acute and chronic renal disease. The prototype of acute glomerulonephritis is acute post-infectious glomerulonephritis. Recently, increased cases of glomerulopathy have been associated with bacterial, viral, and other infections. Acute nephritic syndrome is part of glomerulonephritis with an acute beginning, characterized by hematuria, hypertension, edema, and oliguria due to the reduction of glomerular filtration reflected in an increase of nitrogen compounds.Development: This paper shows a male infant at 2 years and 7 months of age with nephritic syndrome associated to a skin infection, pneumonia, and hepatitis A virus infection.Conclusion: Acute glomerulonephritis may be associated to streptococcus or another coincidental infection. Children with skin infection, hepatitis A, or pneumonia who reveal abnormal urinalysis, hypertension, azotemia, or oliguria should be evaluated for concomitant glomerulonephritis.
The Daugavet property of $C^*$-algebras, $JB^*$-triples, and of their isometric preduals
Julio Becerra-Guerrero,Miguel Martin
Mathematics , 2004,
Abstract: A Banach space $X$ is said to have the Daugavet property if every rank-one operator $T:X\longrightarrow X$ satisfies $\|Id + T\| = 1 + \|T\|$. We give geometric characterizations of this property in the settings of $C^*$-algebras, $JB^*$-triples and their isometric preduals. We also show that, in these settings, the Daugavet property passes to ultrapowers, and thus, it is equivalent to an stronger property called the uniform Daugavet property.
Wavelet transform on the torus: a group theoretical approach
Manuel Calixto,Julio Guerrero,Daniela Rosca
Mathematics , 2013, DOI: 10.1016/j.acha.2014.03.001
Abstract: We construct a Continuous Wavelet Transform (CWT) on the torus $\mathbb T^2$ following a group-theoretical approach based on the conformal group $SO(2,2)$. The Euclidean limit reproduces wavelets on the plane $\mathbb R^2$ with two dilations, which can be defined through the natural tensor product representation of usual wavelets on $\mathbb R$. Restricting ourselves to a single dilation imposes severe conditions for the mother wavelet that can be overcome by adding extra modular group $SL(2,\mathbb Z)$ transformations, thus leading to the concept of \emph{modular wavelets}. We define modular-admissible functions and prove frame conditions.
Motion Estimation via Robust Decomposition with Constrained Rank
German Ros,Jose Alvarez,Julio Guerrero
Computer Science , 2014,
Abstract: In this work, we address the problem of outlier detection for robust motion estimation by using modern sparse-low-rank decompositions, i.e., Robust PCA-like methods, to impose global rank constraints. Robust decompositions have shown to be good at splitting a corrupted matrix into an uncorrupted low-rank matrix and a sparse matrix, containing outliers. However, this process only works when matrices have relatively low rank with respect to their ambient space, a property not met in motion estimation problems. As a solution, we propose to exploit the partial information present in the decomposition to decide which matches are outliers. We provide evidences showing that even when it is not possible to recover an uncorrupted low-rank matrix, the resulting information can be exploited for outlier detection. To this end we propose the Robust Decomposition with Constrained Rank (RD-CR), a proximal gradient based method that enforces the rank constraints inherent to motion estimation. We also present a general framework to perform robust estimation for stereo Visual Odometry, based on our RD-CR and a simple but effective compressed optimization method that achieves high performance. Our evaluation on synthetic data and on the KITTI dataset demonstrates the applicability of our approach in complex scenarios and it yields state-of-the-art performance.
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