Efficient simulation of stochastic chemical kinetics with the Stochastic Bulirsch-Stoer extrapolation method

BackgroundBiochemical systems with relatively low numbers of components must be simulated stochastically in order to capture their inherent noise. Although there has recently been considerable work on discrete stochastic solvers, there is still a need for numerical methods that are both fast and accurate. The Bulirsch-Stoer method is an established method for solving ordinary differential equations that possesses both of these qualities.ResultsIn this paper, we present the Stochastic Bulirsch-Stoer method, a new numerical method for simulating discrete chemical reaction systems, inspired by its deterministic counterpart. It is able to achieve an excellent efficiency due to the fact that it is based on an approach with high deterministic order, allowing for larger stepsizes and leading to fast simulations. We compare it to the Euler ?-leap, as well as two more recent ?-leap methods, on a number of example problems, and find that as well as being very accurate, our method is the most robust, in terms of efficiency, of all the methods considered in this paper. The problems it is most suited for are those with increased populations that would be too slow to simulate using Gillespie’s stochastic simulation algorithm. For such problems, it is likely to achieve higher weak order in the moments.ConclusionsThe Stochastic Bulirsch-Stoer method is a novel stochastic solver that can be used for fast and accurate simulations. Crucially, compared to other similar methods, it better retains its high accuracy when the timesteps are increased. Thus the Stochastic Bulirsch-Stoer method is both computationally efficient and robust. These are key properties for any stochastic numerical method, as they must typically run many thousands of simulations

The regional distribution of spanish unemployment. A spatial analysis

This paper proposes a set of tools to analyse the regional distribution of unemployment. As we are interested in the characteristics of the whole distribution, we complement results from the traditional regression analysis with those from the estimation of its external shape before and after being conditioned to factors underlying regional unemployment. Besides, the paper explicitly addresses the spatial characteristics of the distribution, and the empirical model build to determine the explanatory factors includes spatial effects. We apply this framework to the study of the provincial distribution of unemployment rates in Spain in the mid-eighties and late nineties, when economic transformations could have caused different regional responses. Results point to increasing spatial dependence in the distribution of regional unemployment rates, and a change in the factors causing regional differentials over the last decade.

Oscillatory regulation of Hes1: discrete stochastic delay modelling and simulation

Discrete stochastic simulations are a powerful tool for understanding the dynamics of chemical kinetics when there are small-to-moderate numbers of certain molecular species. In this paper we introduce delays into the stochastic simulation algorithm, thus mimicking delays associated with transcription and translation. We then show that this process may well explain more faithfully than continuous deterministic models the observed sustained oscillations in expression levels of hes1 mRNA and Hes1 protein

Los programas deportivos radiofónicos en la medianoche: La supremacía del fútbol en los contenidos

Every midnight, sports programs are one of the basic references in radio programming. The three major Spanish radio networks, SER, Onda Cero and COPE, competing in the same time schedules for sports fans to win listeners. The desire to give football information sometimes comes to extreme lengths in specialized sports media, leaving other sports. This article will analyze the contents of these areas overlapping with the Christmas holiday break from football matches in Spain.Cada medianoche, los programas deportivos son uno de los referentes básicos en la programación radiofónica. Las tres principales cadenas radiofónicas españolas, SER, Onda Cero y COPE, compiten en la misma franja por ganar oyentes. El afán por dar información futbolística llega a veces hasta extremos insospechados en los medios especializados deportivos, que dejan de lado otras disciplinas deportivas. En este artículo, se analizarán los contenidos de estos espacios coincidiendo en parte con el descanso vacacional navideño de la competición futbolística en España

El uso de la web 2.0 en la comunicación de los profesionales de la Salud en Colombia

This study analyzes the factors that determine the use of webs 2.0 by professionals and students (i.e., residents) in the nursing and medical fields in Colombia when providing health care in the medical centers in which they are employed. Using correlational-explanatory research, this paper conducted interviews of a representative sample of members (n= 424) of the studied population (e=+/- 4.8 and 1-α=0.95).  The obtained data reveal a low level of use of currently available digital resources despite the high level of self-perception of this use and a moderately high assessment of the usefulness of these types of resource while performing professional work. Gender, age, having children, socioeconomic status, training level and the years of experience of the members of the study population significantly affect the use of webs 2.0 social-level resources available today. Improve this use and facilitate a change of attitude for it could simplify meeting their responsibilities within the Colombian health-care system.Tras una década de desarrollo, la aplicación de soluciones de Salud 2.0 ha comenzado a introducirse en Colombia. La investigación analiza cuáles son los factores que determinan el uso de la web 2.0 por parte de profesionales y estudiantes (residentes) del campo de la enfermería y la medicina en Colombia cuando desempeñan la atención sanitaria en los centros médicos donde laboran. Mediante una investigación de carácter correlacional-explicativa, se aplicaron encuestas a una muestra representativa de miembros de la población estudiada con e=+/- 4,8 y 1-α=0,95. Los datos obtenidos permiten apreciar, entre otros alcances, un bajo nivel de aprovechamiento real de los recursos digitales dispuestos en la actualidad, a pesar del alto nivel de auto-percepción sobre dicho aprovechamiento y la valoración medio-alta, sobre la utilidad de este tipo de recursos para el ejercicio de sus labores profesionales. Así mismo, se aprecia cómo el género, la edad, la posesión de hijos, el estrato socioeconómico, el nivel formativo y el tiempo de experiencia de los miembros de la población de estudio inciden significativamente en el nivel de aprovechamiento de recursos web 2.0 disponibles en la actualidad a nivel social que pueden facilitar el ejercicio de su función dentro del sistema de salud colombiano

Diverse Cultural Thought In The European Context Through Music Collaboration Networks

Networking in current music education and models, projects and platforms are a means for recovering the importance of music education as a part of artistic education. Music education has value in itself, both in the international and European context, not only from an instrumental or interdisciplinary perspective, but also as a critical reflection on reality, forming an integral part of society which cannot be removed. Art, due to its non-instrumental nature, constitutes a source of living standards and allows the development of the human sensibility which contributes to the acquisition of skills related with perception, and which make up valuable tools for the cognitive process of the science. Networking projects through music education contribute to diverse cultural thought, which places value on European cultural heterogeneity through music, promotes cultural integration and diversity of tastes beyond prevailing and homogenising musical trends

MasterFinger: Multi-finger Haptic Interface for Collaborative Environments

This paper introduces the Master Finger development and application, a multi-finger haptic interface for virtual object manipulation. This haptic device, with a modular interface, is specially designed to perform collaborative tasks. Each module is in charge of managing the haptic interaction with a finger. The mechanical structure of the module is based on a serial-parallel structure linked to the finger thimble by a gimble with its own controller. Cooperative applications based onMasterFinger-2 (MF2) are also described in this study. Results from these applications show that multifinger interface is a significant leap in haptic devices since precise object grasping and collaborative manipulation by using two hands are successfully performed

Analytic model of a cache-only memory architecture

An approximate analytic model of a shared memory multiprocessor with a Cache Only Memory Architecture (COMA), the busbased Data Difussion Machine (DDM), is presented and validated. It describes the timing and interference in the system as a function of the hardware, the protocols, the topology and the workload. Model results have been compared to results from an independent simulator. The comparison shows good model accuracy specially for non-saturated systems, where the errors in response times and device utilizations are independent of the number of processors and remain below 10% in 90% of the simulations. Therefore, the model can be used as an average performance prediction tool that avoids expensive simulations in the design of systems with many processors

Can Sadurní (Begues, Baix Llobregat), de la captación de recursos abióticos al inicio de la mineria de aluminio-fosfatos (10500-4000 Cal Ane) en el Macizo de Garraf

Ya desde la fase microlaminar del Epipaleolítico el macizo de Garraf ha ofrecido y satisfecho a sus pobladores de la mayoría de materias primas. Por lo que se refiere a las materias de carácter abiótico, observaremos como las diferentes poblaciones que se han sucedido en la ocupación de la cueva, fueron incrementando la captación y el uso de las materias primas que ofrecen las diferentes formaciones geológicas del macizo hasta descubrir las mineralizaciones de aluminofosfatos del basamento paleozoico, iniciar su explotación y propiciar los primeros intercambios a escala extra-regional. Una explotación que, dado su volumen y trascendencia, probablemente condicionó el abandono del yacimiento de Can Sadurní y el traslado a la llanura cuaternaria en la que se emplaza la actual población de Gavà