Recursive linear estimation for discrete time systems in the presence of different multiplicative observation noises

This paper describes a design for a least mean square error estimator in discrete time systems where the components of the state vector, in measurement equation, are corrupted by different multiplicative noises in addition to observation noise. We show how known results can be considered a particular case of the algorithm stated in this paperState estimation, multiplicative noise, uncertain observations

Laplace Approximation for Divisive Gaussian Processes for Nonstationary Regression

The standard Gaussian Process regression (GP) is usually formulated under stationary hypotheses: The noise power is considered constant throughout the input space and the covariance of the prior distribution is typically modeled as depending only on the difference between input samples. These assumptions can be too restrictive and unrealistic for many real-world problems. Although nonstationarity can be achieved using specific covariance functions, they require a prior knowledge of the kind of nonstationarity, not available for most applications. In this paper we propose to use the Laplace approximation to make inference in a divisive GP model to perform nonstationary regression, including heteroscedastic noise cases. The log-concavity of the likelihood ensures a unimodal posterior and makes that the Laplace approximation converges to a unique maximum. The characteristics of the likelihood also allow to obtain accurate posterior approximations when compared to the Expectation Propagation (EP) approximations and the asymptotically exact posterior provided by a Markov Chain Monte Carlo implementation with Elliptical Slice Sampling (ESS), but at a reduced computational load with respect to both, EP and ESS

Temporal characterization of the requests to Wikipedia

This paper presents an empirical study about the temporal patterns characterizing the requests submitted by users to Wikipedia. The study is based on the analysis of the log lines registered by the Wikimedia Foundation Squid servers after having sent the appropriate content in response to users' requests. The analysis has been conducted regarding the ten most visited editions of Wikipedia and has involved more than 14,000 million log lines corresponding to the traffic of the entire year 2009. The conducted methodology has mainly consisted in the parsing and filtering of users' requests according to the study directives. As a result, relevant information fields have been finally stored in a database for persistence and further characterization. In this way, we, first, assessed, whether the traffic to Wikipedia could serve as a reliable estimator of the overall traffic to all the Wikimedia Foundation projects. Our subsequent analysis of the temporal evolutions corresponding to the different types of requests to Wikipedia revealed interesting differences and similarities among them that can be related to the users' attention to the Encyclopedia. In addition, we have performed separated characterizations of each Wikipedia edition to compare their respective evolutions over time

A quantitative examination of the impact of featured articles in Wikipedia

This paper presents a quantitative examination of the impact of the presentation of featured articles as quality content in the main page of several Wikipedia editions. Moreover, the paper also presents the analysis performed to determine the number of visits received by the articles promoted to the featured status. We have analyzed the visits not only in the month when articles awarded the promotion or were included in the main page, but also in the previous and following ones. The main aim for this is to assess the attention attracted by the featured content and the different dynamics exhibited by each community of users in respect to the promotion process. The main results of this paper are twofold: it shows how to extract relevant information related to the use of Wikipedia, which is an emerging research topic, and it analyzes whether the featured articles mechanism achieve to attract more attention

La mujer como objeto (modelo) y sujeto (fotógrafa) en la fotografía

The aim of this study is to show whether the role of women in the contemporary photography has evolved. We analyze the situation of women as objects (model) and subjects (photographer) starting from a study of the first women photographers. We examine the social conditions and the influence of the images transmitted by the media in the construction and projection of the image of women, analyzing the pioneering and most relevant photographers in contemporary history. Finally we evaluate the gender inequality in relation to the ability to control the projected image of women and their identity through their body in the field of feminist photography.Este trabajo cuestiona la evolución del papel de las mujeres en el ámbito fotográfico contemporáneo. A partir del estudio de las primeras mujeres fotógrafas, se analiza la situación de las mujeres como objeto (modelo) y sujeto (fotógrafa); se reflexiona sobre los condicionamientos sociales y la influencia de las imágenes que transmiten los medios de comunicación en la construcción y proyección de la imagen femenina en la fotografía, analizando las fotógrafas pioneras y más relevantes en la historia contemporánea. Finalmente se valora la desigualdad de género en relación con la capacidad de control sobre la imagen proyectada de las mujeres y su identidad a través del cuerpo en el ámbito de la fotografía feminista

Exciton Gas Compression and Metallic Condensation in a Single Semiconductor Quantum Wire

We study the metal-insulator transition in individual self-assembled quantum wires and report optical evidences of metallic liquid condensation at low temperatures. Firstly, we observe that the temperature and power dependence of the single nanowire photoluminescence follow the evolution expected for an electron-hole liquid in one dimension. Secondly, we find novel spectral features that suggest that in this situation the expanding liquid condensate compresses the exciton gas in real space. Finally, we estimate the critical density and critical temperature of the phase transition diagram at $n_c\sim1\times10^5$ cm$^{-1}$ and $T_c\sim35$ K, respectively.Comment: 4 pages, 5 figure

Tensorial analisis of the superposed deformation in the easthern border of the Madrid basin

An analysis of Neogene brittle deformation using fault populatíon analysis methods has been carried out between the SW border of the Iberian Range and Altomira Range. Two main paleostress fields have been established: 1) N70E - N120E compression (Altomira paleostress field) ofLate Oligocene - Early Miocene age that induced the formation of the SW border of Iberian Range and Altomira - Pareja thrust belts with reverse and strike-slip faults. 2) N140-N160E compression (Guadarrama paleostress field) of Middle Aragonian - early Pleistocene age that reactivated previous faults with strikeslip movement along the Iberian Range. A superposition of two regional stress fields (Iberian and Guadarrama) is proposed to explain E-W compression that formed Altomira Range. Stress tensorial additions have been realized to check this hypothesis

PERSPECTIVAS DE LOS GRADUADOS UNIVERSITARIOS NO TRADICIONALES SOBRE LAS PRÁCTICAS: COMPETENCIAS, EMPLEABILIDAD Y TRANSICIÓN AL MERCADO LABORAL EN ESPAÑA

Employability has become a principal aim of universities in Europe and beyond. In this context, internships are a central strategy for the promotion of employability. This qualitative study, conducted in Spain and based on biographical-narrative interviews, focuses on the voices and experiences of 25 non-traditional university graduates, all from the field of social sciences, on employability, internships, and skills. The data collected are analysed based on four categories: training received at the university; the influence of internships on employability; assessment of the internships; and perspectives on skills in demand and mismatches between graduate profiles and labour market demands. Graduates feel the internships has not helped in the transition to the workplace. Graduates have criticised the lack of connection between university and workplace, the short duration of internships, and the insufficient focus on professional and transversal skills. The results also suggest that universities should develop more initiatives to improve internships, working in coordination with employers and other stakeholders.A empregabilidade tornou-se um objetivo principal das universidades na Europa e fora dela. Neste contexto, os estagios são uma estratégia central para a promoção da empregabilidade. Este estudo qualitativo, realizado na Espanha e baseado em entrevistas biográfico-narrativas, enfoca as vozes e experiências de 25 graduados universitários não tradicionais, todos do campo das ciências sociais, sobre empregabilidade, estágios e habilidades. Os dados coletados são analisados com base em quatro categorias: treinamento recebido na universidade; influência dos estágios na empregabilidade; avaliação dos estágios; e perspectivas sobre habilidades em demanda e desencontros entre perfis de graduados e demandas do mercado de trabalho. Os estagiários sentem que os estágios não têm ajudado na transição para o mercado de trabalho. Os graduados têm criticado a falta de conexão entre universidade e mercado de trabalho, a curta duração dos estágios e o foco insuficiente nas habilidades profissionais e transversais. Os resultados também sugerem que as universidades deveriam desenvolver mais iniciativas para melhorar os estágios, trabalhando em coordenação com empregadores e outras partes interessadas.    La empleabilidad se ha convertido en un objetivo importante de las universidades en Europa y fuera de ella. En este contexto, las prácticas son una estrategia fundamental para la promoción de la empleabilidad. Este estudio cualitativo, realizado en España y basado en entrevistas biográficas, se centra en las voces y experiencias de 25 graduados universitarios no tradicionales, todos ellos del ámbito de las ciencias sociales, sobre la empleabilidad, las prácticas y las competencias. Los datos recogidos se analizan sobre la base de cuatro categorías: la formación recibida en la universidad; la influencia de las prácticas en la empleabilidad; la evaluación de las prácticas; y las perspectivas sobre las competencias demandadas y los desajustes entre los perfiles de los graduados y las demandas del mercado de trabajo. Los graduados consideran que las prácticas no han ayudado a la transición al mercado laboral. Los graduados han criticado la falta de conexión entre la universidad y el mercado laboral, la corta duración de las prácticas y la insuficiente atención a las competencias profesionales y transversales. Los resultados también sugieren que las universidades deberían desarrollar más iniciativas para mejorar las prácticas, trabajando en coordinación con los empleadores y otros grupos interesados. &nbsp