Molecular dynamics simulations of complex shaped particles using Minkowski operators

The Minkowski operators (addition and substraction of sets in vectorial spaces) has been extensively used for Computer Graphics and Image Processing to represent complex shapes. Here we propose to apply those mathematical concepts to extend the Molecular Dynamics (MD) Methods for simulations with complex-shaped particles. A new concept of Voronoi-Minkowski diagrams is introduced to generate random packings of complex-shaped particles with tunable particle roundness. By extending the classical concept of Verlet list we achieve numerical efficiencies that do not grow quadratically with the body number of sides. Simulations of dissipative granular materials under shear demonstrate that the method complies with the first law of thermodynamics for energy balance.Comment: Submitted to Phys. Rev.

Extending the Petri box calculus with time

PBC (Petri Box Calculus) is a process algebra where real parallelism of concurrent systems can be naturally expressed. One of its main features is the definition of a denotational semantics based on Petri nets, which emphasizes the structural aspects of the modelled systems. However, this formal model does not include temporal aspects of processes, which are necessary when considering real-time systems. The aim of this paper is to extend the existing calculus with those temporal aspects. We consider that actions are not instantaneous, that is, their execution takes time. We present an operational semantics and a denotational semantics based on timed Petri nets. Finally, we discuss the introduction of other new features such as time-outs and delays. Throughout the paper we assume that the reader is familiar with both Petri nets and PBC

Nuclear structure studies of exotic nuclei : the cases of ³¹Ar y ³³Ar

Tesis de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, leída el 23/11/2018En esta tesis se presentan los resultados del diseño, puesta a punto, medida y análisis de resultados del experimento IS577 realizado en ISOLDE-CERN. En este experimento se midió la desintegración beta de dos núcleos atómicos exóticos: ³¹Ar y ³³Ar. Son núcleos alejados del valle de la estabilidad y se desexcitan mediante la emisión de protones (tras la desintegración beta), fenómemo que solo se da en núcleos deficientes en neutrones en este caso con Z>N, altamente inestables. La energía disponible para que se produzca la desintegración beta es grande y además la energía de enlace de un protón es muy baja; como consecuencia, varios canales de desintegración resultan accesibles, de forma que se pueblan niveles ligados (emisión gamma) y no ligados dándose el proceso de emisión de protones. Nuestro objetivo es estudiar mediante la espectroscopía de protones y de radiación gamma, los mecanismos por los que se producen dichas emisiones, así como estudiar la estructura nuclear de los núcleos de cloropoblados en la desintegración beta de ³¹Ar y ³³Ar...This thesis presents the results of the design, commissioning, measurement and analysis of the results of the IS577 experiment carried out at ISOLDE-CERN. In this experiment, the decays of two exotic atomic nuclei were measured: ³¹Ar y ³³Ar. They are nuclei far from the valley of stability and they are de-excited by the emission of protons (after beta decay), a phenomenon that only occurs in neutron-deficient nuclei in this case with Z>N, highly unstable. The energy window for beta emission is large and the proton separation energy is very low; as a consequence, many decay channels are open, and bound and unbound levels are populated in the daughter nucleus allowing for the proton emission process. Our objective is to study, by means of proton and gamma radiation spectroscopy, the mechanisms by which these emissions are produced, as well as to study the nuclear structure of the chlorine nucleipopulated in the beta decay of ³¹Ar y ³³Ar...Fac. de Ciencias FísicasTRUEunpu

Ratcheting of granular materials

We investigate the quasi-static mechanical response of soils under cyclic loading using a discrete model of randomly generated convex polygons. This response exhibits a sequence of regimes, each one characterized by a linear accumulation of plastic deformation with the number of cycles. At the grain level, a quasi-periodic ratchet-like behavior is observed at the contacts, which excludes the existence of an elastic regime. The study of this slow dynamics allows to explore the role of friction in the permanent deformation of unbound granular materials supporting railroads and streets.Comment: Changed content Submitted to Physical Review Letter

Características sociodemográficas del parto domiciliario en pobladoras del Centro Poblado Kerguer durante el período 2010 – 2016

Objetivo: Identificar las características sociodemográficas del parto domiciliario en pobladoras del Centro Poblado Kerguer durante el período 2010-2016. Material y Métodos: Estudio Descriptivo transversal. Se incluyeron todas las pobladoras que tuvieron parto domiciliario durante el período 2010-2016 en el Centro Poblado Kerguer. Resultados: 33 participantes. La edad promedio de las participantes fue 30,64 ± 6,93 años. El 97% son convivientes. El 12,1% son analfabetas y el 6,1% tienen secundaria completa. El 84,5% tienen antecedentes de parto domiciliario. El 87,9% de los partos domiciliarios fueron atendidos por Partera. Los principales motivos de la elección del parto domiciliario fueron Por tradición en un 63,6% y Por distancia 36,4%. Conclusión: Las principales características sociodemográficas del parto domiciliario fueron el bajo nivel socioeconómico y el bajo nivel de instrucción. Los principales motivos de la elección de parto domiciliario fueron Por tradición y Por distancia. La mayoría de los partos fueron atendidos por parteras

Drenaje pleural neonatal artesanal para neumotórax

Letter to the Editor (without abstract)Carta al Editor (sin resumen

Hemopericardio masivo por sobreanticoagulación en portador de prótesis valvular mecánica: Reporte de caso

Background: Massive pericardial effusion represents less than 2% of cardiac surgery complications. Case Report: Male, 31 years old, with mechanical mitral valve, who were readmitted three weeks after cardiac surgery, due to massive hemopericardium and INR of 6,23. He underwent the pericardial window through the left mini-thoracotomy, draining 1500ml. Conclusions: It is necessary a systematic monitoring to maintain desired anticoagulation values and to identify possible complications early.Introducción: Los derrames pericárdicos masivos representan menos del 2% de las complicaciones de los post operados de cirugía cardíaca. Reporte de caso: Varón de 31 años, portador de prótesis mitral mecánica, que reingresa a la tercera semana de la cirugía por hemopericardio masivo e INR en 6,23. Fue sometido a ventana pleuropericárdica de emergencia, drenando un volumen de 1500ml. Conclusiones: Es necesario un seguimiento sistemático para mantener un rango de anticoagulación deseado e identificar tempranamente posibles complicaciones

Mobile Synchronizing Petri Nets: A Choreographic Approach for Coordination in Ubiquitous Systems

AbstractThe term Ubiquitous Computing was coined by Mark Weiser almost two decades ago. Despite all the time that has passed since Weiser's vision, ubiquitous computing still has a long way ahead to become a pervasive reality. One of the reasons for this may be the lack of widely accepted formal models capable of capturing and analyzing the complexity of the new paradigm. We propose a simple Petri Net based model to study some of its main characteristics. We model both devices and software components as a special kind of coloured Petri Nets, located in locations, that can move to other locations and synchronize with other co-located nets, offering and requesting services. We obtain an amenable model for ubiquitous computing, due to its graphical representation. We present our proposal in a progressive way, first presenting a basic model where coordination is formalized by the synchronized firing of pairs of compatible transitions that offer and request a specific service, and ad hoc networks are modeled by constraining mobility by the dynamic acquisition of locality names. Next, we introduce a mechanism for the treatment of robust security properties, namely the generation of fresh private names, to be used for authentication properties

Modularis: Modular Relational Analytics over Heterogeneous Distributed Platforms

The enormous quantity of data produced every day together with advances in data analytics has led to a proliferation of data management and analysis systems. Typically, these systems are built around highly specialized monolithic operators optimized for the underlying hardware. While effective in the short term, such an approach makes the operators cumbersome to port and adapt, which is increasingly required due to the speed at which algorithms and hardware evolve. To address this limitation, we present Modularis, an execution layer for data analytics based on sub-operators, i.e.,composable building blocks resembling traditional database operators but at a finer granularity. To demonstrate the advantages of our approach, we use Modularis to build a distributed query processing system supporting relational queries running on an RDMA cluster, a serverless cloud platform, and a smart storage engine. Modularis requires minimal code changes to execute queries across these three diverse hardware platforms, showing that the sub-operator approach reduces the amount and complexity of the code. In fact, changes in the platform affect only sub-operators that depend on the underlying hardware. We show the end-to-end performance of Modularis by comparing it with a framework for SQL processing (Presto), a commercial cluster database (SingleStore), as well as Query-as-a-Service systems (Athena, BigQuery). Modularis outperforms all these systems, proving that the design and architectural advantages of a modular design can be achieved without degrading performance. We also compare Modularis with a hand-optimized implementation of a join for RDMA clusters. We show that Modularis has the advantage of being easily extensible to a wider range of join variants and group by queries, all of which are not supported in the hand-tuned join.Comment: Accepted at PVLDB vol. 1