Determination of division algebras with 243 elements

Finite nonassociative division algebras (i.e., finite semifields) with 243 elements are completely classified.Comment: 6 pages, 3 table

Stability Analysis of a Bose-Einstein Condensate Trapped in a Generic Potential

We investigate the dynamical behavior of the Gross-Pitaevskii equation for a Bose-Einstein condensate trapped in a spherical power law potential restricted to the repulsive case, from the dynamical system formalism point of view. A five-dimensional dynamical system is found (due the symmetry of the Gross-Pitaevskii equation interacting with a potential), where the Thomas-Fermi approximation constrains the parameter space of solutions. We show that for values of the power law exponent equal or smaller than 2 the system seems to be stable. However, when the corresponding exponent is bigger than 2, the instability of the system grows when the power law exponent grows, indicating that large values of the aforementioned parameter can be related to a loss in the number of particles from the condensed state. This fact can be used also to show that the stability conditions of the condensate are highly sensitive to the exponent associated with the external potential.Comment: 9 pages, 2 figure

Investigación aplicada: entonces y hoy

Investigación aplicada: entonces y ho

Langvarandi verkir

Neðst á síðunni er hægt að nálgast greinina í heild sinni með því að smella á hlekkinn View/OpenVið sem sjúkraþjálfarar hittum oft fólk sem er illa haldið af slæmum verkjum. Þetta geta t.d. verið einstaklingar sem þjást af króniskum bakverkjum, fengið hnykkáverka, lent í aflimun eða í öðrum raunum sem skapa þessa sáru langvarandi verki. Oft hefur þetta fólk gengið á milli lækna og annars heilbrigðisfólks, farið í allar mögulegar rannsóknir en oftar en ekki finnst ekki orsök verkjanna. Í þessari grein verður fjallað um þær lífeðlisfræðilegu breytingar sem eiga sér stað í mænu og heila þegar sársauki á sér stað og einnig hvað verður til þess að sársauki verður krónískur

Depth-based Outlier Detection for Grouped Smart Meters: a Functional Data Analysis Toolbox

Smart metering infrastructures collect data almost continuously in the form of fine-grained long time series. These massive time series often have common daily patterns that are repeated between similar days or seasons and shared between grouped meters. Within this context, we propose a method to highlight individuals with abnormal daily dependency patterns, which we term evolution outliers. To this end, we approach the problem from the standpoint of Functional Data Analysis (FDA), by treating each daily record as a function or curve. We then focus on the morphological aspects of the observed curves, such as daily magnitude, daily shape, derivatives, and inter-day evolution. The proposed method for evolution outliers relies on the concept of functional depth, which has been a cornerstone in the literature of FDA to build shape and magnitude outlier detection methods. In conjunction with our evolution outlier proposal, these methods provide an outlier detection toolbox for smart meter data that covers a wide palette of functional outliers classes. We illustrate the outlier identification ability of this toolbox using actual smart metering data corresponding to photovoltaic energy generation and circuit voltage records

Domain wall dynamics in expanding spaces

We study the effects on the dynamics of kinks due to expansions and contractions of the space. We show that the propagation velocity of the kink can be adiabatically tuned through slow expansions/contractions, while its width is given as a function of the velocity. We also analyze the case of fast expansions/contractions, where we are no longer on the adiabatic regime. In this case the kink moves more slowly after an expansion-contraction cycle as a consequence of loss of energy through radiation. All these effects are numerically studied in the nonlinear Klein-Gordon equations (both for the sine-Gordon and for the phi^4 potential), and they are also studied within the framework of the collective coordinate evolution equations for the width and the center of mass of the kink. These collective coordinate evolution equations are obtained with a procedure that allows us to consider even the case of large expansions/contractions.Comment: LaTeX, 18 pages, 2 figures, improved version to appear in Phys Rev

A demand based algorithm for rapid updating of replicas

In many Internet scale replicated system, not all replicas can be dealt with in the same way, since some will be in greater demand than others. In the case of weak consistency algorithms, we have observed that updating first replicas having most demand, a greater number of clients would gain access to updated content in a shorter period of time. In this work we have investigated the benefits that can be obtained by prioritizing replicas with greater demand, and considerable improvements have been achieved. In zones of higher demand, the consistent state is reached up to six times quicker than with a normal weak consistency algorithm, without incurring the additional costs of the strong consistency.Peer Reviewe

Análisis dinámico de los efectos de la estructura de demanda sobre crecimiento y medio ambiente en Andalucía

En este trabajo se relaciona la especialización productiva de una región española (Andalucía) con el crecimiento económico, el consumo de recursos naturales y la polución atmosférica. Para ello, nos hemos centrado en dos de los recursos naturales básicos, como son el agua y la energía, así como en otros indicadores de calidad atmosférica, tales como las emisiones de CO y SO2. La metodología seguida parte de la aplicación de la dinámica de sistemas, proponiendo un modelo que pone en relación ciertas variables medio ambientales con las de otros subsistemas (laboral y macroeconómico). En el modelo se integran las tablas input-output de Andalucía (Instituto de Estadística de Andalucía) y los resultados recientes, respecto a consumos de agua, energía y emisión de contaminantes, obtenidos en la contabilidad ambiental, elaborada por la Consejería de Medio Ambiente de esta Comunidad Autónoma.environment economics, dymamic systems, input-output analysis, regional analysis