Recovering Latent Signals from a Mixture of Measurements using a Gaussian Process Prior

In sensing applications, sensors cannot always measure the latent quantity of interest at the required resolution, sometimes they can only acquire a blurred version of it due the sensor's transfer function. To recover latent signals when only noisy mixed measurements of the signal are available, we propose the Gaussian process mixture of measurements (GPMM), which models the latent signal as a Gaussian process (GP) and allows us to perform Bayesian inference on such signal conditional to a set of noisy mixture of measurements. We describe how to train GPMM, that is, to find the hyperparameters of the GP and the mixing weights, and how to perform inference on the latent signal under GPMM; additionally, we identify the solution to the underdetermined linear system resulting from a sensing application as a particular case of GPMM. The proposed model is validated in the recovery of three signals: a smooth synthetic signal, a real-world heart-rate time series and a step function, where GPMM outperformed the standard GP in terms of estimation error, uncertainty representation and recovery of the spectral content of the latent signal.Comment: Published on IEEE Signal Processing Letters on Dec. 201

Stochastic multi-scale models of competition within heterogeneous cellular populations: simulation methods and mean-field analysis

We propose a modelling framework to analyse the stochastic behaviour of heterogeneous, multi-scale cellular populations. We illustrate our methodology with a particular example in which we study a population with an oxygen-regulated proliferation rate. Our formulation is based on an age-dependent stochastic process. Cells within the population are characterised by their age. The age-dependent (oxygen-regulated) birth rate is given by a stochastic model of oxygen-dependent cell cycle progression. We then formulate an age-dependent birth-and-death process, which dictates the time evolution of the cell population. The population is under a feedback loop which controls its steady state size: cells consume oxygen which in turns fuels cell proliferation. We show that our stochastic model of cell cycle progression allows for heterogeneity within the cell population induced by stochastic effects. Such heterogeneous behaviour is reflected in variations in the proliferation rate. Within this set-up, we have established three main results. First, we have shown that the age to the G1/S transition, which essentially determines the birth rate, exhibits a remarkably simple scaling behaviour. This allows for a huge simplification of our numerical methodology. A further result is the observation that heterogeneous populations undergo an internal process of quasi-neutral competition. Finally, we investigated the effects of cell-cycle-phase dependent therapies (such as radiation therapy) on heterogeneous populations. In particular, we have studied the case in which the population contains a quiescent sub-population. Our mean-field analysis and numerical simulations confirm that, if the survival fraction of the therapy is too high, rescue of the quiescent population occurs. This gives rise to emergence of resistance to therapy since the rescued population is less sensitive to therapy

Direct Metal Laser Fabrication of Cu Slabs from Powder Precursor: Surface Depth of Melt and Furnace Temperature Issues

A DMLF processing unit based on a raster-scanned 80 W CO2 laser beam has been developed to process single layers of metallic powder precursor. The process chamber provides atmosphere control (high vacuum and inert gas refill) besides temperature elevation up to 700 o C. In this work, copper powder precursor is confined inside a refractory steel mask surrounded by an aluminum oxide jacket that acts as insulator. The powder layers can have thicknesses of 0,5 and 1 mm. An infrared pyrometer measures in real time the temperature at one location in the surface of the powder bed. Scan speed, scan step, and furnace temperature have been varied to find combinations of such parameters that render surface melting and maximum densification. Partially melted samples were produced and their mass density was measured. Micro-hardness and surface roughness were also measured along the resolidified surface, the first rendering an average of 80,6 HV compared to the 90-105 HV of oxygen free copper, while the second resulting in an 8 μm Ra value. Maximum melt of depth achieved is ~0,15 mm followed by a sintered layer.Mechanical Engineerin

Poly-Harmonic Distortion Model Extraction in Charge-Controlled One-Port Devices

A charge-controlled, one-port device is used to describe and discuss the extraction procedure of a Poly-Harmonic Distortion (PHD) model in detail. For this case, both voltage and current waveforms are shown to be enough to fully characterize the PHD model. It is also shown that all the information specifically required for this PHD model definition can be stored in the Fourier coefficients of the incremental conductance and capacitance. The results are validated by comparing them with those obtained using a commercial circuit simulation tool.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Carbon materials as template for the preparation of mixed oxides with controlled morphology

Resumen del libro de actas del Congreso: 5th Czech-Italian-Spanish Conference on Molecular Sieves and Catalysis, celebrado en Segovia del 16 al 19 de junio de 2013Bulk mixed oxide catalysts are widely used for many applications, such as catalysts for selective oxidation processes, electrocatalysts for fuel cells, gas sensors, and solid oxide electrolysers for the production of hydrogen. VPO (vanadium and phosphorous oxides) are one of the bulk mixed oxide materials which are of interest nowadays since they are active catalysts for saturated hydrocarbon activation. With the conventional synthesis procedures for preparing bulk mixed oxides is really difficult to control the morphology and the porous structure of these materials. In practice, there are just a few works about the synthesis of mixed oxide materials with controlled morphology. The aim of this work was to describe new approaches for the preparation of VPO mixed oxides materials with spherical morphology. A carbon material was prepared using cellulose as starting material by hydrothermal treatment with phosphoric acid at 200ºC and carbonized at 500ºC. SEM analysis showed that carbon spheres with diameter up to 0.5 m were prepared by this procedure. These phosphorous containing carbon material was impregnated with the appropriate amount of vanadium oxide species in order to obtain a monolayer of VOx species on the surface of the carbon materials following a procedure described previously (1). By this manner, a carbon supported VOx material with spherical morphology was obtained (VPO/Csph). The calcination of this material was optimized in order to obtain VPO spheres with diameter up to 1-2 m and with BET area values close to 100 m2/g. Figure 1 shows a SEM image of this sample (VPOsph). The presence of vanadium pyrophosphate phase, which has been described as the active phase of this catalytic system, was identified by XRD and Raman spectroscopy. Thus, the chemical composition as well as the morphology and porous structure of these new spherical materials makes them quite promising as catalysts

Activated carbons as catalytic support for Cu nanoparticles

There are a wide range of catalytic applications for Cu-based nanoparticles materials, since Cu is an abundant and inexpensive metal and Cu nanoparticles possess unusual electrical, thermal and optical properties. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. A previous work have explored the possibilities of SBA-15 (1,2) as support for Cu nanoparticles. In the present contribution, those results will be compared with the use of a carbon material as support, since activated carbon present many advantages with respect SBA, as the high surface area.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

La personalidad eficaz en adolescentes diagnosticados de trastorno por déficit de atención con hiperactividad (TDAH)

El objetivo de la presente investigación es estudiar el perfil de la población adolescente de entre 12 y 18 años diagnosticados de TDAH, a partir del Cuestionario de Personalidad Eficaz CPE-Es/Ch (Dapelo, Marcone, Martín del Buey, Martín Palacio y Fernández, 2006). Se administró dicho cuestionario a un total de 250 adolescentes diagnosticados de TDAH a lo largo de todo el territorio nacional. Se compararon los resultados de dicha población con una muestra control de 112 adolescentes pertenecientes a un colegio del Principado de Asturias con el mismo rango de edad y sin ningún tipo de diagnóstico. Los resultados mostraron que para la población de adolescentes diagnosticados de TDAH existe un total de cuatro tipologías. No se encontraron diferencias significativas cuando el adolescente recibe un tratamiento psicológico y/o farmacológico en comparación con los que no lo reciben. Tampoco existen diferencias en la puntuación de Personalidad Eficaz en cuanto a la edad se refiere

Crisis del agua, turismo y variabilidad climática en la isla de San Andrés

Through Decrees 0170 of April 15, 2016 and 0340 of August 16, 2017, the departmental government declares the beginning and the end of the public calamity due to the lack of water on the island of San Andrés (Colombia) during 15 months. The reduction of the water supply of 2016 entails social demonstrations against the departmental administration and generates conflicts in the tourism sector and the resident population in timely access to water, in the collective institutional imaginary as the culprit of the situation of the climatic phenomenon Southern Oscillation El Niño in that year (that brought with it a significant decrease in rainfall and thus in the supply of drinking water). This article explores additional factors that contributed to the decrease of water supply on the island, such as the incipient control of the aqueduct networks distribution leakage, the lack of demographic planning for an increasing sun and beach tourism and a possible discordance with the expected climate change in response to the decrease in rainfall (and, therefore, the supply of groundwater), the main source of water supply in San Andrés. In addition,  this article presents an analysis, for a term of 10 years before a water crisis, of water supply in scenarios of climatic variability, after technical and operational losses in the aqueduct systems, against the water demand of tourists and residents of those same years and a projection to 2040; finding that if the current patterns of aquifer exploitation and management of the available supply continue, the same water problems will be experienced in the first half of each year, regardless of a climatic event enso El Niño.Por medio de los Decretos 0170 del 15 de abril de 2016 y 0340 del 16 de agosto de 2017, la Gobernación departamental declaró el inicio y el final de la calamidad pública por desabastecimiento hídrico en la isla de San Andrés (Colombia), que tuvo una duración de 15 meses. La reducida oferta hídrica de 2016 llevó a manifestaciones sociales en contra de la administración departamental, generó conflictos entre el sector turístico y la población residente por el acceso oportuno al agua y dejó en el imaginario colectivo institucional como culpable de la situación presentada al fenómeno climatológico ENOS (El Niño oscilación del sur) de ese año, que trajo consigo una disminución importante en las precipitaciones y, con ello, en la oferta de agua potable. En este artículo se exploran factores adicionales que contribuyeron a la disminución de la oferta de agua en la isla, como el incipiente control de fugas en redes de distribución del acueducto, la falta de planificación demográfica para un turismo de sol y playa creciente, y una prospectiva territorial discordante con el cambio climático esperado en atención a la disminución de lluvias (y, por ende, la oferta de agua subterránea), principal fuente de abastecimiento hídrico en San Andrés. Adicionalmente, el artículo presenta un análisis –para 10 años previos a la crisis hídrica– de oferta de agua bajo escenarios de variabilidad climática, después de pérdidas técnicas y operacionales en los sistemas de acueducto, con respecto a la demanda de agua de turistas y residentes de esos mismos años y proyección a 2040. Se encuentra que, de seguir los patrones actuales de explotación de acuíferos y manejo de la oferta disponible, se tendrían los mismos problemas hídricos en el primer semestre de cada año, independientemente de un evento climatológico