The backtracking survey propagation algorithm for solving random K-SAT problems

Discrete combinatorial optimization has a central role in many scientific disciplines, however, for hard problems we lack linear time algorithms that would allow us to solve very large instances. Moreover, it is still unclear what are the key features that make a discrete combinatorial optimization problem hard to solve. Here we study random K-satisfiability problems with $K=3,4$, which are known to be very hard close to the SAT-UNSAT threshold, where problems stop having solutions. We show that the backtracking survey propagation algorithm, in a time practically linear in the problem size, is able to find solutions very close to the threshold, in a region unreachable by any other algorithm. All solutions found have no frozen variables, thus supporting the conjecture that only unfrozen solutions can be found in linear time, and that a problem becomes impossible to solve in linear time when all solutions contain frozen variables.Comment: 11 pages, 10 figures. v2: data largely improved and manuscript rewritte

Heart Rate Variability for Outcome Prediction in Intracerebral and Subarachnoid Hemorrhage: A Systematic Review

This systematic review presents clinical evidence on the association of heart rate variability with outcome prediction in intracerebral and subarachnoid hemorrhages. The literature search led to the retrieval of 19 significant studies. Outcome prediction included functional outcome, cardiovascular complications, secondary brain injury, and mortality. Various aspects of heart rate recording and analysis, based on linear time and frequency domains and a non-linear entropy approach, are reviewed. Heart rate variability was consistently associated with poor functional outcome and mortality, while controversial results were found regarding the association between heart rate variability and secondary brain injury and cardiovascular complications

Stream programming framework for global ilumination techniques using a GPU

Los procesadores de streams están comenzando a ser una alternativa accesible para implementar técnicas de rendering asistidas por hardware que habitualmente estaban relegadas al uso offline. Nosotros elaboramos un marco de trabajo para procesamiento de streams basado en los conceptos del modelo de Stream Programming, seleccionamos el algoritmo de Photon Mapping y una GPU (Graphics Processing Unit) Nvidia para una implementación de un caso de prueba. Definimos un conjunto de clases en C++ para encapsular los componentes (kernels y streams) de este nuevo paradigma, usando OpenGL y el lenguaje Cg. Nuestra aplicación combina el método de Photon Mapping y una estructura de aceleración BVH (Bounding Volumes Hierarchy) en un pipeline de renderizado basado casi completamente en la GPU. Finalmente, evaluamos su desempeño usando un modelo de caja de Cornell.Stream processors are becoming an affordable alternative to implement hardware assisted rendering techniques which were usually relegated to offline usage. We built a stream processing framework based on the Stream Programming Model concepts, selected the Photon Mapping algorithm and an NVIDIA GPU (Graphics Processing Unit) as a test case implementation of a Global Illumination technique. We defined a set of C++ classes to encapsulate the components (kernels and streams) of this new paradigm, using OpenGL and Cg language. Our application combines the Photon Splatting method and the BVH (Bounding Volumes Hierarchy) acceleration structure into a rendering pipeline relying almost entirely on the GPU. Finally, we evaluated its performance using a Cornell Box model.V Workshop de Computación Gráfica, Imágenes Y VisualizaciónRed de Universidades con Carreras en Informática (RedUNCI

Stripes in the extended t-t' Hubbard model: A Variational Monte Carlo analysis

By using variational quantum Monte Carlo techniques, we investigate the instauration of stripes (i.e., charge and spin inhomogeneities) in the Hubbard model on the square lattice at hole doping δ=1/8, with both nearest- (t) and next-nearest-neighbor hopping (t′). Stripes with different wavelengths λ (denoting the periodicity of the charge inhomogeneity) and character (bond- or site-centered) are stabilized for sufficiently large values of the electron-electron interaction U/t. The general trend is that λ increases going from negative to positive values of t′/t and decreases by increasing U/t. In particular, the λ=8 stripe obtained for t′=0 and U/t=8 [L.F. Tocchio, A. Montorsi, and F. Becca, SciPost Phys. 7, 21 (2019)] shrinks to λ=6 for U/t≳10. For t′/t<0, the stripe with λ=5 is found to be remarkably stable, while for t′/t>0, stripes with wavelength λ=12 and λ=16 are also obtained. In all these cases, pair-pair correlations are highly suppressed with respect to the uniform state (obtained for large values of |t′/t|), suggesting that striped states are not superconducting at δ=1/8

Nuevas normas de auditoría en Argentina

En términos generales, la resolución técnica 37 (2013) tiene como finalidad modificar las normas profesionales de auditoría vigentes en la Argentina, fundamentalmente para incluir nuevos servicios ya contemplados en las normas internacionales de aseguramiento y servicios relacionados, adoptadas ahora por la FACPCE, y adecuar las normas de antigua data, hasta el momento existentes. La justificación del tema está dada por la gran importancia en materia de auditoría que implican los cambios introducidos por las nuevas resoluciones, ya que cambiarán no sólo las normas, sino también los tipos de informes y los servicios brindados, no así la metodología para la ejecución de las labores y procedimientos de auditoría, adoptando nuevas situaciones ya contemplados por las normas internacionales. Además el objetivo primordial de este trabajo es que sirva de base para el estudio de la materia tanto para los nuevos alumnos como así también para aquellos que estudiaron el campo de la auditoría a través de la normativa anterior, como así también cualquier otro interesado, pudiendo visualizar y sobretodo comparar fácilmente las modificaciones de fondo entre una y otra.Fil: Di Leo, Alessandro Franco. Universidad Nacional de Cuyo. Facultad de Ciencias Económicas.Fil: Sibecas, Nicolás Eduardo. Universidad Nacional de Cuyo. Facultad de Ciencias Económicas.Fil: Victorio Marino, Federico José. Universidad Nacional de Cuyo. Facultad de Ciencias Económicas.Fil: Villa Chiartano, Federico Nicolás. Universidad Nacional de Cuyo. Facultad de Ciencias Económicas

Ventilation Targets for Patients Undergoing Mechanical Thrombectomy for Acute Ischemic Stroke: A Systematic Review

Mechanical thrombectomy (MT) has become a standard treatment for acute ischemic stroke (AIS) caused by large vessel occlusion (LVO). Recent evidence suggests that general anesthesia (GA) and mechanical ventilation do not lead to inferior neurologic outcomes if compared to non-GA. However, the guidelines lack specific recommendations for ventilation targets during MT under GA. This systematic review aims to identify ventilation strategies correlating with better neurological outcomes in AIS patients undergoing MT, particularly focusing on oxygenation and carbon dioxide (CO2) targets. A systematic search of multiple databases was conducted to identify human studies reporting the correlation between ventilation strategies and neurological outcomes in MT for AIS. Eligible studies included clinical trials, observational studies, and case–control studies. Out of 157 studies assessed, 11 met the inclusion criteria. Five studies investigated oxygenation targets, while six studies explored CO2 targets. The published studies highlighted the controversial role of supplemental normobaric oxygen therapy and its potential association with worse outcomes. Regarding CO2 targets, the studies identified a potential association between end tidal CO2 levels and functional outcomes, with hypocapnia being unfavorable. This systematic review demonstrates that the current available evidence still lacks strength to suggest specific ventilation targets, but it highlights the potential risks of hyperoxia and hypocapnia in this specific cohort of patients

Mesoporous silica nanoparticles as carriers of active agents for smart anticorrosive organic coatings: a critical review

Mesoporous silica nanoparticles with properly designed textural properties and tailored release of corrosion inhibitors are highly efficient smart carriers for advanced anticorrosive nanocomposite coatings

Stochastic Gradient Descent-like relaxation is equivalent to Glauber dynamics in discrete optimization and inference problems

Is Stochastic Gradient Descent (SGD) substantially different from Glauber dynamics? This is a fundamental question at the time of understanding the most used training algorithm in the field of Machine Learning, but it received no answer until now. Here we show that in discrete optimization and inference problems, the dynamics of an SGD-like algorithm resemble very closely that of Metropolis Monte Carlo with a properly chosen temperature, which depends on the mini-batch size. This quantitative matching holds both at equilibrium and in the out-of-equilibrium regime, despite the two algorithms having fundamental differences (e.g.\ SGD does not satisfy detailed balance). Such equivalence allows us to use results about performances and limits of Monte Carlo algorithms to optimize the mini-batch size in the SGD-like algorithm and make it efficient at recovering the signal in hard inference problems.Comment: 14 pages, 5 figure