Competition of rotation and stratification in flux concentrations

In a strongly stratified turbulent layer, a uniform horizontal magnetic field can become unstable to spontaneously form local flux concentrations due to a negative contribution of turbulence to the large-scale (mean-field) magnetic pressure. This mechanism, called the negative effective magnetic pressure instability (NEMPI), is of interest in connection with dynamo scenarios where most of the magnetic field resides in the bulk of the convection zone, and not at the bottom. Recent work using the mean-field hydromagnetic equations has shown that NEMPI becomes suppressed at rather low rotation rates with Coriolis numbers as low as 0.1.}{Here we extend these earlier investigations by studying the effects of rotation both on the development of NEMPI and on the effective magnetic pressure. We also quantify the kinetic helicity from direct numerical simulations (DNS) and compare with earlier work.}{To calculate the rotational effect on the effective magnetic pressure we consider both DNS and analytical studies using the $\tau$ approach. To study the effects of rotation on the development of NEMPI we use both DNS and mean-field calculations of the 3D hydromagnetic equations in a Cartesian domain.}{We find that the growth rates of NEMPI from earlier mean-field calculations are well reproduced with DNS, provided the Coriolis number is below about 0.06. In that case, kinetic and magnetic helicities are found to be weak. For faster rotation, dynamo action becomes possible. However, there is an intermediate range of rotation rates where dynamo action on its own is not yet possible, but the rotational suppression of NEMPI is being alleviated.}{Production of magnetic flux concentrations through the suppression of turbulent pressure appears to be possible only in the upper-most layers of the Sun, where the convective turnover time is less than 2 hours.}Comment: 13 pages, 13 figures submitted to A&

On fractional derivatives and primitives of periodic functions

In this paper we prove that the fractional derivative or the fractional primitive of a $T$-periodic function cannot be a $\tilde{T}$-periodic function, for any period $\tilde{T}$, with the exception of the zero function.Comment: 12 page

Centres d'excel·lència en la formació empresarial: orientació i impacte

En aquesta conferència es posen de manifest les claus de l'èxit de les dues escoles de negoci pioneres a Catalunya i Espanya, ESADE i IESE. El seu ampli renom internacional i uns estudis que són catalogats d'alt nivell d'excel·lència han col·laborat a assolir aquest succés. Gràcies al seu sistema d'ensenyament basat en conceptes com el rigor, el coneixement útil i el nivell internacional, han permès omplir el buit que hi havia a Europa als anys 1950 pel que fa a la formació de directius en escoles de negocis, que fins aleshores quedava reduïda als Estats Units.This conference analyses the keys to success of two pioneering business schools in Catalonia and Spain, IESE and ESADE, which are also reference points in the international business school framework. The renown of these institutions, as well as their teaching methods, based on high quality, helped them to achieve their goal. The use of practical studies and the rigour of these schools rendered it possible to fill a management training gap which at that time was only covered in the United States

Numerical analysis of run-up oscillations under dissipative conditions

This paper presents laboratory and numerical simulations of run-up induced by irregular waves breaking on a gentle-sloping planar beach. The experimental data are well reproduced by a numerical model based on the nonlinear shallow water equations. By extending the incoming wave conditions considered in the laboratory experiments, the model is applied to study the run-up variability under highly energetic incoming conditions. The numerical results support the idea that, for cases characterized by the same incident peak frequency, infragravity run-up increases almost linearly with the offshore significant wave height. Moreover, the most energetic conditions lead to an upper limit of the swash similarity parameter of about 1.8. © 2014 Elsevier B.V

Tuberculosis de la sínfisis del pubis : a propósito de un caso clínico.

Se presenta un caso muy infrecuente de tuberculosis osteoarticular de localización en la sínfisis del pubis. Destaca la dificultad de su diagnóstico por lo inespecífico de su clínica, por el desconocimiento de enfermedad pulmonar o lesión primaria tuberculosa, y la dificultad para aislar al propio bacilo tuberculoso. Establecemos los diagnósticos diferenciales más importantes con los que se puede confundir esta patología antes de llegar a un diagnóstico certero y se valoran los síntomas, signos y hallazgos radiológicos más frecuentes que contribuyen al diagnóstico, así como el tratamiento específico empleado.We presen t a cas e o f an infrecuen t locatio n o f osteoarticula r tuber - culosis a t th e pubi x xymphisis. This patolog y is difficult t o determine , specil y if ther e doe s no t exit a pulmonar y o r primar y TBC lesion . Also , th e difficult t o obtai n a positiv e microbiolog y cultur e increase s th e dela y i n diagnosis. We establis h all posibl e differencia l diagnoses. Whic h ca n lea d t o confusio n i n this typ e o f pathology . A carefu l evaluatio n o f most commo n simptoms, sign s an d radiologien e fínding s ar e described , a s wel l as, th e specifi c treatmen t employe d i n this particuler e case