Modeling and analysis of random and stochastic input flows in the chemostat model

In this paper we study a new way to model noisy input flows in the chemostat model, based on the Ornstein-Uhlenbeck process. We introduce a parameter β as drift in the Langevin equation, that allows to bridge a gap between a pure Wiener process, which is a common way to model random disturbances, and no noise at all. The value of the parameter β is related to the amplitude of the deviations observed on the realizations. We show that this modeling approach is well suited to represent noise on an input variable that has to take non-negative values for almost any time.European Commission (EC). Fondo Europeo de Desarrollo Regional (FEDER)Ministerio de Economía y Competitividad (MINECO). EspañaJunta de Andalucí

Lithium in the Hyades L5 brown dwarf 2MASS J04183483+2131275

Aims. From the luminosity, effective temperature and age of the Hyades brown dwarf 2MASS J04183483+2131275 (2M0418), substellar evolutionary models predict a mass in the range 39−55 Jupiter masses (MJup) which is insufficient to produce any substantial lithium burning except for the very upper range >53 MJup. Our goal is to measure the abundance of lithium in this object, test the consistency between models and observations and refine constraints on the mass and age of the object. Methods. We used the 10.4-m Gran Telescopio Canarias (GTC) with its low-dispersion optical spectrograph to obtain ten spectra of 2277 s each covering the range 6300–10 300 Å with a resolving power of R ~ 500. Results. In the individual spectra, which span several months, we detect persistent unresolved Hα in emission with pseudo equivalent widths (pEW) in the range 45–150 Å and absorption lines of various alkalis with the typical strengths found in objects of L5 spectral type. The lithium resonance line at 6707.8 Å is detected with pEW of 18 ± 4 Å in 2M0418 (L5). Conclusions. We determine a lithium abundance of log N(Li) = 3.0 ± 0.4 dex consistent with a minimum preservation of 90% of this element which confirms 2M0418 as a brown dwarf with a maximum mass of 52 MJup. We infer a maximum age for the Hyades of 775 Myr from a comparison with the BHAC15 models. Combining recent results from the literature with our study, we constrain the mass of 2M0418 to 45–52 MJup and the age of the cluster to 580–775 Myr (1σ) based on the lithium depletion boundary method.We thank the referee for a detailed report that improved the quality of this manuscript. This research has been supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under the grants AYA2015- 69350-C3-2-P and AYA2015-69350-C3-3-P. We thank Yakiv Pavlenko for his calculations of equivalent widths at different temperatures, Isabelle Baraffe for her models, and Eduardo Martín for sharing his results prior to publication. This work is based on observations made with the Gran Telescopio Canarias (GTC), operated on the island of La Palma in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (programme GTC77- 16B led by Pérez Garrido). This research has made use of the Simbad and Vizier databases, operated at the Centre de Données Astronomiques de Strasbourg (CDS), and of NASA’s Astrophysics Data System Bibliographic Services (ADS). We thank John Stauffer for kindly providing the optical spectra of the K and M Hyades members published in 1997 (Stauffer et al. 1997a)

Una presidencia de acción conjunta

Han pasado casi tres meses de la presidencia española de la Unión Europea. Un momento histórico para España. A pesar de las dificultades, mantenemos intacta la ilusión por cumplir con un programa que estamos transformando en acciones concretas, y la satisfacción por ver traducidas esas acciones en mejoras palpables para el conjunto de la Unión así como para nuestros socios y vecinos. Es precisamente esa voluntad de cooperación y esfuerzo común, el germen que está haciendo posible el desarrollo de las más ambiciosas y prioritarias líneas de acción de nuestra presidencia. Desde la renovada estructura institucional, hasta la implementación de las medidas de recuperación económica y creación de empleo de calidad enmarcadas en la Estrategia UE 2020, pasando por el Servicio Europeo de Acción Exterior, España está haciendo todo lo posible para sentar las bases de la nueva Europa del siglo XXI

España y Turquia: dos países y un destino

Si tuviéramos que definir el estado de las relaciones entre España y Turquía, éstas podrían calificarse de muy buenas. Y es que los amigos turcos son un socio y vecino de primer orden. Compartimos una visión común en numerosas áreas de trabajo, ya sea en el terreno político, económico, comercial o de la seguridad colectiva. Turquía es un gran país en todos los sentidos

The rule of law in response to the COVID-19 emergency

This work presents an analysis of the measures adopted by leading democratic countries in response to the COVID-19 emergency, and the compatibility issues that arose between these measures and the guarantees of the rule of law. The global and simultaneous scope of this serious emergency facilitates comparative analysis and reveals their advantages and their shortcomings. The aim of the article is to evaluate the various extra-constitutional methods employed in response to the exception as well as the state of exception model, based on the regulation of extraordinary situations and the measures to be adopted. Lastly, the analysis focuses on the contradictions that have arisen as a consequence of the use and non-use of the state of exception model in the response to COVID-19 in Europe

Primeros datos sobre la estratigrafía de la región Chiclana de Segura-río Madera (Zona Prebética, provincia de Jaén)

La presente nota es un avance sobre las características estratigráficas de un sector de la Zona Prebética. Fundamentalmente se estudian las series mesozoicas estableciendo sus correlaciones. Sobre el Paleozoico de la Meseta se depositan diferentes formaciones de aguas someras con frecuentes cambios de facies y, como en todos los bordes de la Meseta, caracterizadas por una influencia continental en la sedimentación que se traduce en la existencia de episodios marinos y continentales de mayor o menor amplitud. Se incluye un esquema geológico de conjunto

An UHF frequency-modulated continuous wave wind profiler - receiver and audio module development

Projecte final de carrera fet en col.laboració amb University of Massachusetts - Amherst, the Microwave Sensing Laboratory (MIRSL)The measurement of winds and processes taking place in the atmosphere is a fun- damental requirement in both research and operational meteorology. This project is focused on the processes taking place in the lower troposphere called the atmospheric boundary layer (ABL). The ABL is important meteorologically in terms of assessing of convective instability. The entrainment zone at the top of the ABL acts as a lid on rising (and cooling) air parcels due to the temperature inversion. An external mechanism such as geographically forced uplift, vigorous surface heating or drylines, can break the entrainment layer, allowing the capped air parcels to rise freely. As a result, vigorous convection will begin producing severe thunderstorms. ABL research and studies help (i) develop and improve existing numerical weather prediction models, (ii) understand the transfer of hear, water vapor and momentum between the Earth and the atmosphere, (iii) re ne the analytical description of tur- bulent processes and (iv) quantify the absorption and emission in the troposphere, which is a major factor in shaping climate on Earth. The e ect of the troposphere on wave propagation has also been studied extensively for the purposes of improving radio communications.The main reason for the radar development is the need of continous monitoring of the winds and elds in the atmosphere, improving the in-situ measurements. Conven- tional radar pro ler technologies usually are able to make atmospheric measurements of the boundary layer, but precluding the lower part of the ABL, (around 150 meters). The Frequency Modulated Continuous Wave, Spaced Antenna (FMCW-SA) Radar, that is being developed in University of Massachusetts - Amherst, at the Microwave Sensing Laboratory (MIRSL), will allow measurements of the lower part of the ABL. The use of FMCW radars is introduced in order to improved the limitations of pulsed radars. Pulsed radars are limited by the pulse-width and switching speed of the transmit-receive switches because of the use of a common antennas for both functions. The pulsed nature of the radar dictates a high transmitter power, and consequently the need for switches that are both faster and high powered. FMCW radar alleviate this problem by using separate antennas for transmit and receive, also being able to be used at short ranges. The problem in dual-antenna systems is parallax at low altitudes due to the spatially separated antenna apertures, and some uncertainty in the actual sampling volume. The primary objective of this thesis, is to explain the previous results and the problems encountered on the FMCW Wind Pro ler Radar, and to provide a detailed account of the work one in order to x remaining issues. Several problems were encountered on the radar's receiver. Noise and leakage were still not allowing the radar to achieve sensitivity enough to work properly. To solve it, the receiver was modi ed. This thesis, provides a detailed account of modi cations including a new audio-module, modi ed FPGA and tests to report conclusions