The dependence of assembly bias on the cosmic web

For low-mass haloes, the physical origins of halo assembly bias have been linked to the slowdown of accretion due to tidal forces, which are expected to be more dominant in some cosmic-web environments as compared to others. In this work, we use publicly available data from the application of the Discrete Persistent Structures Extractor (DisPerSE) to the IllustrisTNG magnetohydrodynamical simulation to investigate the dependence of the related galaxy assembly bias effect on the cosmic web. We first show that, at fixed halo mass, the galaxy population displays significant low-mass secondary bias when split by distance to DisPerSE critical points representing nodes ($d_{\rm node}$), filaments ($d_{\rm skel}$), and saddles ($d_{\rm sadd}$), with objects closer to these features being more tightly clustered. The secondary bias produced by some of these parameters exceeds the assembly bias signal considerably at some mass ranges, particularly for $d_{\rm sadd}$. We also demonstrate that the assembly bias signal is reduced significantly when clustering is conditioned to galaxies being close or far from these critical points. The maximum attenuation is measured for galaxies close to saddle points, where less than 35$\%$ of the signal remains. Conversely, objects near voids preserve a fairly pristine effect (almost 85$\%$ of the signal). Our analysis confirms the important role played by the tidal field in shaping assembly bias, but they are also consistent with the signal being the result of different physical mechanisms. Our work introduces some new aspects of secondary bias where the predictions from hydrodynamical simulations can be directly tested with observational data.Comment: 12 pages, 7 figures. Submitted to MNRAS, comments welcom

The dependence of halo bias on age, concentration and spin

Halo bias is the main link between the matter distribution and dark matter halos. In its simplest form, halo bias is determined by halo mass, but there are known additional dependencies on other halo properties which are of consequence for accurate modeling of galaxy clustering. Here we present the most precise measurement of these secondary-bias dependencies on halo age, concentration, and spin, for a wide range of halo masses spanning from 10$^{10.7}$ to 10$^{14.7}$ $h^{-1}$ M$_{\odot}$. At the high-mass end, we find no strong evidence of assembly bias for masses above M$_{vir}$ $\sim10^{14}$ $h^{-1}$ M$_{\odot}$. Secondary bias exists, however, for halo concentration and spin, up to cluster-size halos, in agreement with previous findings. For halo spin, we report, for the first time, two different regimes: above M$_{vir}\sim$10$^{11.5}$ $h^{-1}$ M$_{\odot}$, halos with larger values of spin have larger bias, at fixed mass, with the effect reaching almost a factor 2. This trend reverses below this characteristic mass. In addition to these results, we test, for the first time, the performance of a multi-tracer method for the determination of the relative bias between different subsets of halos. We show that this method increases significantly the signal-to-noise of the secondary-bias measurement as compared to a traditional approach. This analysis serves as the basis for follow-up applications of our multi-tracer method to real data.Comment: 11 pages, 6 figures, submitted to MNRA

Umbral de intensidad: más allá de los tonos puros

The objective of this study is to determine an intensity threshold based onperceptive discrimination in a manner similar to how the F0 threshold of 1.5-2 Stwas established (Rietveld & Gussenhoven, 1985; Toledo, 2000b; Pamies et al.,2002). In previous studies, an intensity threshold of 3 dB (v. gr. Dorta &Hernández, 2005:99-100) has been used, but it has not been proven that this is theappropriate threshold for the discrimination of normal speech sounds. Therefore,we have designed a discrimination-type perception test in order to determine theminimum intensity necessary to differentiate sounds in a formal context ofcontrolled speech, as opposed to using pure tones as is typical of audiometrystudies. The test was conducted on a set of 74 listeners or judges who comparedand determined whether or not there were differences between proximal stimulidifferentiated by their intensity levels. Our initial hypothesis suggests that theresults of this perception test shall permit us to establish a threshold from 3-5 dB.The results and the statistical analysis of the data confirm our hypothesis,establishing the intensity threshold at 4 dB.El objetivo de este trabajo es determinar un umbral de intensidad a partir de ladiscriminación perceptiva de manera análoga a como se ha establecido en la F0 elumbral de 1,5-2 St (Rietveld y Gussenhoven, 1985; Toledo, 2000b; Pamies et al.,2002). En estudios anteriores se ha utilizado un umbral de intensidad de 3 dB (v.gr. Dorta y Hernández, 2005:99-100) pero no está probado que dicho umbral seaapropiado en la discriminación de sonidos del habla normal. Por ello, hemosdiseñado un test de percepción de tipo discriminante con el propósito dedeterminar la intensidad mínima necesaria para diferenciar sonidos en un contextocontrolado de habla próximo al estilo formal, en lugar de discriminar entre tonospuros como se suele hacer en los estudios de audiometría. El test se aplicó a unconjunto de 74 auditores o jueces que debían comparar y decidir si se dandiferencias entre estímulos próximos diferenciados por distintos niveles deintensidad. Nuestra hipótesis de partida plantea que los resultados del testperceptivo permitirían establecer un umbral que oscile entre 3-5 dB. Los resultadosy el análisis estadístico de los datos permiten confirmar la hipótesis y establecer elumbral de intensidad en 4 dB

Modification of Coronary-Prone Behaviors in Coronary Patients of Low Socio-Economic Status

Este estudio pretende conocer la efectividad de un tratamiento cognitivo-conductual aplicado a grupos de enfermos coronarios de un nivel educativo y status social predominantemente bajo para modificar conductas prono-coronarias. Método: La distribución de los 98 varones enfermos coronarios en un grupo experimental y dos de control se realizó al azar. Los tres grupos recibieron el tratamiento médico estándar. El grupo experimental recibió adicionalmente un tratamiento psicológico y uno de los dos grupos de control recibió además un programa de educación para la salud. Los resultados mostraron que sólo el grupo que recibió el tratamiento psicológico redujo significativamente su Comportamiento Apresurado y su Prisa-Impaciencia después del tratamiento y durante los dos años de seguimiento posteriores al tratamiento. La depresión también se redujo sólo en este grupo tras los dos años de seguimiento. Los resultados se consideran un primer paso fiable en el proceso de validar este programa diseñado para mejorar la calidad de vida de los pacientes coronarios.The purpose of this study is to determine the effectiveness of a group cognitive-behavioral treatment to modify coronary-prone behaviors in patients from a fairly low social and educational level. Participants were 98 male coronary patients randomly allocated to one experimental and two control groups. All groups received standard medical treatment. The experimental group received an additional psychological treatment and one of the two control groups received a health education treatment. Results showed that only the psychological treatment group significantly reduced Pressured Drive and Speed-Impatience after treatment, and at 1- and 2-year follow-ups. Depression was also significantly reduced only in this group at 2-year follow-up. The results are considered a reliable first step in the process of validating this program designed to improve coronary heart disease patients’ quality of life