Uncovering differential equations from data with hidden variables.

SINDy is a method for learning system of differential equations from data by solving a sparse linear regression optimization problem [Brunton, Proctor, and Kutz, Proc. Natl. Acad. Sci. USA 113, 3932 (2016)PNASA60027-842410.1073/pnas.1517384113]. In this article, we propose an extension of the SINDy method that learns systems of differential equations in cases where some of the variables are not observed. Our extension is based on regressing a higher order time derivative of a target variable onto a dictionary of functions that includes lower order time derivatives of the target variable. We evaluate our method by measuring the prediction accuracy of the learned dynamical systems on synthetic data and on a real data set of temperature time series provided by the Réseau de Transport d'Électricité. Our method provides high quality short-term forecasts and it is orders of magnitude faster than competing methods for learning differential equations with latent variables.

Mobile telephones: a comparison of radiated power between 3G VoIP calls and 3G VoCS calls.

The purpose of this study is to assess the mean RF power radiated by mobile telephones during voice calls in 3G VoIP (Voice over Internet Protocol) using an application well known to mobile Internet users, and to compare it with the mean power radiated during voice calls in 3G VoCS (Voice over Circuit Switch) on a traditional network. Knowing that the specific absorption rate (SAR) is proportional to the mean radiated power, the user's exposure could be clearly identified at the same time. Three 3G (High Speed Packet Access) smartphones from three different manufacturers, all dual-band for GSM (900 MHz, 1800 MHz) and dual-band for UMTS (900 MHz, 1950 MHz), were used between 28 July and 04 August 2011 in Paris (France) to make 220 two-minute calls on a mobile telephone network with national coverage. The places where the calls were made were selected in such a way as to describe the whole range of usage situations of the mobile telephone. The measuring equipment, called "SYRPOM", recorded the radiation power levels and the frequency bands used during the calls with a sampling rate of 20,000 per second. In the framework of this study, the mean normalised power radiated by a telephone in 3G VoIP calls was evaluated at 0.75% maximum power of the smartphone, compared with 0.22% in 3G VoCS calls. The very low average power levels associated with use of 3G devices with VoIP or VoCS support the view that RF exposure resulting from their use is far from exceeding the basic restrictions of current exposure limits in terms of SAR.

Assessment of real exposure to GSM mobile telephones using the SYRPOM.

A mobile telephone user's exposure to the radio-frequency electromagnetic field depends heavily on the power their telephone radiates, which can vary widely according to requests from the base station. This study presents the design and development of a system called SYstem for Radiated POwer Measurement (SYRPOM), which measures the power radiated by a mobile telephone. This study also describes the tests carried out on the system itself and gives the results of two measuring campaigns it has been possible to perform in this way. The first such campaign consisted of assessing the mean power received by a typical mobile telephone user carrying out various activities. The second campaign was aimed at (1) comparing the mean radiated power when stationary and when moving and (2) assessing and contrasting different models of handsets in terms of the mean radiated power. The SYRPOM has proved to be a flexible, easy-to-use high-performance and innovative tool for carrying out this kind of studies.

Del código al deseo: del cuerpo en la relación social

Este libro procura definir el papel del cuerpo en las relaciones sociales, comienza por mostrar, a partir de un análisis de los manuales de usos sociales, cómo la interacción corporal está regida por el código riguroso que determina nuestra conducta cotidiana. Al mismo tiempo, esta escenificación de los cuerpos funciona como medio de comunicación entre los individuos. El cuerpo, por último, remite a un tercer eje, que es el del deseo: codificado por la cultura nuestro cuerpo es el escenario de una tensión permanente entre el deseo y la ley, la pulsión y el sentido