The envelope of the power spectra of over a thousand \delta Scuti stars. The Tˉeff\bar{T}_{eff}-νmax\nu_{max} scaling relation

CoRoT and Kepler high-precision photometric data allowed the detection and characterization of the oscillation parameters in stars other than the Sun. Moreover, thanks to the scaling relations, it is possible to estimate masses and radii for thousands of solar-type oscillating stars. Recently, a \Delta\nu - \rho relation has been found for \delta Scuti stars. Now, analyzing several hundreds of this kind of stars observed with CoRoT and Kepler, we present an empiric relation between their frequency at maximum power of their oscillation spectra and their effective temperature. Such a relation can be explained with the help of the \kappa-mechanism and the observed dispersion of the residuals is compatible with they being caused by the gravity-darkening effect

Evidence of chaotic modes in the analysis of four delta Scuti stars

Since CoRoT observations unveiled the very low amplitude modes that form a flat plateau in the power spectrum structure of delta Scuti stars, the nature of this phenomenon, including the possibility of spurious signals due to the light curve analysis, has been a matter of long-standing scientific debate. We contribute to this debate by finding the structural parameters of a sample of four delta Scuti stars, CID 546, CID 3619, CID 8669, and KIC 5892969, and looking for a possible relation between these stars' structural parameters and their power spectrum structure. For the purposes of characterization, we developed a method of studying and analysing the power spectrum with high precision and have applied it to both CoRoT and Kepler light curves. We obtain the best estimates to date of these stars' structural parameters. Moreover, we observe that the power spectrum structure depends on the inclination, oblateness, and convective efficiency of each star. Our results suggest that the power spectrum structure is real and is possibly formed by 2-period island modes and chaotic modes

Evidence of amplitude modulation due to Resonant Mode Coupling in the delta Scuti star KIC5892969

A study of the star KIC5892969 observed by the Kepler satellite is presented. Its three highest amplitude modes present a strong amplitude modulation. The aim of this work is to investigate amplitude variations in this star and their possible cause. Using the 4 years-long observations available, we obtained the frequency content of the full light curve. Then, we studied the amplitude and phase variations with time using shorter time stamps. The results obtained are compared with the predicted ones for resonant mode coupling of an unstable mode with lower frequency stable modes. Our conclusion is that resonant mode coupling is consistent as an amplitude limitation mechanism in several modes of KIC5892969 and we discuss to which extent it might play an important role for other delta Scuti stars

Un reto en la fundamentación del conocimiento escolar. Propuesta de contextualización de los procesos y técnicas de la Ciencia en la Educación Científica Básica.

Sin resume

Parameter estimation with non stationary noise in gravitational waves data

The sensitivity of gravitational-waves detectors is characterized by their noise curves which determine the detector's reach and the ability to accurately measure the parameters of astrophysical sources. The detector noise is typically modelled as stationary and Gaussian for many practical purposes. However, physical changes in the state of detectors due to environmental and instrumental factors, including extreme cases where a detector discontinues observing for some time, introduce non-stationarity into the noise. Even slow evolution of the detector sensitivity will affect long duration signals such as binary neutron star (BNS) mergers. Mis-estimation of the noise behavior directly impacts the posterior width of the signal parameters. This becomes an issue for studies which depend on accurate localization volumes such as i) probing cosmological parameters (such as Hubble constant, clustering bias) using cross-correlation methods with galaxies, ii) doing electromagnetic follow-up using localization information from parameter estimation done from pre-merger data. We study the effects of dynamical noise on the parameter estimation of the GW events. We develop a new method to correct dynamical noise by estimating a locally-valid pseudo PSD which is normalized along the time-frequency track of a potential signal. We do simulations by injecting the BNS signal in various scenarios where the detector goes through a period of non-stationarity with reference noise curve of third generation detectors (Cosmic explorer, Einstein telescope). As an example, for a source where mis-modelling of the noise biases the signal-to-noise estimate by even $10\%$, one would expect the estimated localization volume to be either under or over reported by $\sim 30\%$; errors like this, especially in low-latency, could potentially cause follow-up campaigns to miss the true source location

Geochemical clistribution of An in granites with locle mineralizations in As, W ancl Au (NW of Salamanca)

[Resumen] Ante las pruebas de la existencia de altas incidencias de cáncer de próstata en una zona de la provincia de Salamanca y habiendo descartado los factores etiológicos más comunes como su posible causa (MAYOR ARENAL, 1988), se concluye que el único factor de riesgo posible se debería a la existencia de algún factor carcinógeno ambiental. Se realizó una prospección geoquímica de Cd en esta zona dada la relación etiológica de este elemento con dicha enfermedad y se ha constatado que efectivamente existe una anomalía de Cd en los sedimentos de arroyo, que no se corresponde con actividades antropogénicas, sino que son anomalías regionales de los contenidos propios de este elemento en el sustrato, evidenciándose así como potencial factor de riesgo los contenidos de Cd en los suelos desarrollados sobre rocas anómalas en dicho elemento.[Abstract] A high ineidence of prostate cancer has been observed in certain areas of the province of Salamanca. Spain. Mter ruling out the most common etiological factors as the cause (MAYOR ARENAL, 1988) it is concluded that the only possible risk factor must be due to the presence of some environmental carcinogen. In view of the etiological relationship between Cd and the patological state, a study was carried out on the geochemistry of this element in this area. Anomalous amounts of Cd were found in stream sediments and it was observed that this anomaly does not correspond to human activity but rather to high regional amounts of cadmium in the substrate. Thus, the contents of Cd in soils developed over substrates containing naturally-ocurring anomalous amounts of cadmiun should be considered as a real new risk factor

Home i natura: els usos tradicionals del sòl i la pesca

Cabrera, lloc de pas de les antigues rutes marítimes de la mediterrània occidental, illa en els límits de l'habitable, ha estat escassament poblada. La naturalesa, d'una banda, i els condicionants socials i històrics, de l'altra, s'han aliat per allunyar la societat. Així i tot, l'home ha utilitzat els recursos naturals de l'Arxipèlag. Les activitats ramadera, agrícola, forestal i pesquera es repeteixen al llarg de la història amb intensitat variable. D'altra banda, l'ús militar i, més modernament, el turístic, també han tingut repercussions sobre el paisatge. En aquest article feim un breu repàs de les activitats tradicionals de l'home a Cabrera, analitzant-les des de la perspectiva històrica.The harsh nature and social and historic constraints have made Cabrera be nearly always very scantly populated during all its history. The antique merchant ship routes have made use of the port of Cabrera, and the natural resources of the island have always been exploited (farming, livestock raising and fishing). In more recent times Cabrera has been used military and now days the most important usage of the archipelago is tourism. We discuss the traditional activities of man on Cabrera with a historical perspective

Propiedades mecánicas y resistencia de aortas ascendentes patológicas

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El medi lenític de S'Albufera de Mallorca

Al segle passat, i amb l'objectiu de dessecar S'Albufera, s'enturaren estanys i es construí un sistema de canals que condueixen les aigües de forma regular cap a la mar. El que abans era un gradient de divagació de les aigües amb poca energia potencial s'ha transformat en un dràstic gradient amb alguns estanys com l'estany de la Font de Sant Joan, el des Colombar, el des Cibollar, el des Ponts i petits estanys d'aigües intermitents que són objecte del present estudi. Els estanys presenten diferents propietats físico-quimiques i morfològiques i, en conseqüència, tenen un model de dinàmica anual particular. Exceptuant l'estany des Cibollar, altament eutròfic i meromiòtic, els estanys tenen una dinàmica dominada per process os naturals com ara canvis de salinitat i períodes de producció-descomposició. Es pot resumir la dinàmica de la manera següent: primaveres amb inici de producció i sota una creixent salinització. Estius productius i altament salinitzats. Tardors desalinitzades amb descomposició de la biomassa produïda a l'estiu. Hiverns relativament poc salinitzats i amb materia mineralitzada.In the last century and with the aims of dessication of the Albufera many lagoons were filled up and a canal system was made to lead waters directly to the sea. This change transformed a water dispersal gradient with low potential energy into a strong gradient with some ponds and lagoons, such as: Font de Sant Joan, Colombar lagoons, Cibollar, Ponts and small ponds with intermittent waters. The lagoons display different physico-chemical features and annual dynamics. With the exception of the Cibollar, which is strongly eutrophic and meromictic, the lagoons display natural dynamics such as changes in salinity and periods of production-decomposition. One may summarize as follows: spring seasons under the influence of the sea with incipient production, summer production with high salinity, desalinized autumns with decomposition of the summer production and low salinity winters with mineralized matter

Un reto en la fundamentación del conocimiento escolar. Propuesta de contextualización de los procesos y técnicas de la Ciencia en la Educación Científica Básica.

Sin resume