Beauty and mate choice: What evolutionary biology can teach us

We tend to regard beauty as the product of our education, the quintessence of cultural refinement, and we often emphasise the relative nature of beauty. That is why many find it shocking that the perception of beauty, especially human beauty, has a clear biological explanation, one that is largely independent from our education and culture. People are surprised because not only do the characteristics that define beauty originate in biology, but they are also universal and common to all members of our species.; Tendemos a considerar la belleza como el producto destilado de nuestra educación, la quintaesencia de nuestro refinamiento cultural. Además, a menudo destacamos el relativismo de la belleza. Por este motivo, muchos encuentran chocante que la percepción de la belleza, especialmente la belleza humana, tenga una clara explicación biológica, en gran medida independiente de nuestra educación y de nuestra cultura, y les sorprende descubrir que las características que definen la belleza no solo tienen sentido biológico, sino que además son universales, comunes a todos los miembros de nuestra especie.; Tendim a considerar la bellesa com el producte destil·lat de la nostra educació, la quinta essencia del nostre refinament cultural. A més, sovint destaquem el relativisme de la bellesa. Per aquest motiu, molts troben xocant que la percepció de la bellesa, especialment la bellesa humana, tinga una clara explicació biològica, en gran manera independent de la nostra educació i cultura, i els sorprèn descobrir que les característiques que defineixen la bellesa no només tenen sentit biològic, sinó que a més són universals, comunes a tots els membres de la nostra espècie

The Dominance of Metal-Rich Streams in Stellar Halos: A Comparison Between Substructure in M31 and Lambda-CDM Models

Extensive photometric and spectroscopic surveys of the Andromeda galaxy (M31) have discovered tidal debris features throughout M31's stellar halo. We present stellar kinematics and metallicities in fields with identified substructure from our on-going SPLASH survey of M31 red giant branch stars with the DEIMOS spectrograph on the Keck II 10-m telescope. Radial velocity criteria are used to isolate members of the kinematically-cold substructures. The substructures are shown to be metal-rich relative to the rest of the dynamically hot stellar population in the fields in which they are found. We calculate the mean metallicity and average surface brightness of the various kinematical components in each field, and show that, on average, higher surface brightness features tend to be more metal-rich than lower surface brightness features. Simulations of stellar halo formation via accretion in a cosmological context are used to illustrate that the observed trend can be explained as a natural consequence of the observed dwarf galaxy mass-metallicity relation. A significant spread in metallicity at a given surface brightness is seen in the data; we show that this is due to time effects, namely the variation in the time since accretion of the tidal streams' progenitor onto the host halo. We show that in this theoretical framework a relationship between the alpha-enhancement and surface brightness of tidal streams is expected, which arises from the varying times of accretion of the progenitor satellites onto the host halo. Thus, measurements of the alpha-enrichment, metallicity, and surface brightness of tidal debris can be used to reconstruct the luminosity and time of accretion onto the host halo of the progenitors of tidal streams.Comment: 11 pages, 6 figures, published in Ap

Optimization of Track Etched Makrofol Etching Conditions for Short-term Exposure Duration

AbstractExposure time of nuclear track detectors at humid environments is normally limited to a few weeks because filter used to avoid humidity is not completely waterproof and, after several months, some parts of detector start to degrade. In other really extreme measurement conditions, like high aerosol content, high or low temperatures, etc., the exposure time also requires a reduction. Then detector detection limit becomes a problem, unless radon concentrations were high. In those cases where radon levels are not high enough a better detection efficiency is required. In our laboratory we use passive detectors based on the track etched Makrofol DE foil covered with aluminized Mylar and they are analyzed by means of an electrochemical etching. Our standard etching conditions allow analyzing detectors generally exposed for periods between three and six months. We have optimized our etching conditions to reduce the exposure time down to a month for common radon concentration values

Correlations in the three-dimensional Lyman-alpha forest contaminated by high column density absorbers

Correlations measured in three dimensions in the Lyman-alpha forest are contaminated by the presence of the damping wings of high column density (HCD) absorbing systems of neutral hydrogen (HI; having column densities $N(\mathrm{HI}) > 1.6\times10^{17}\,\mathrm{atoms}\,\mathrm{cm}^{-2}$), which extend significantly beyond the redshift-space location of the absorber. We measure this effect as a function of the column density of the HCD absorbers and redshift by measuring 3D flux power spectra in cosmological hydrodynamical simulations from the Illustris project. Survey pipelines exclude regions containing the largest damping wings. We find that, even after this procedure, there is a scale-dependent correction to the 3D Lyman-alpha forest flux power spectrum from residual contamination. We model this residual using a simple physical model of the HCD absorbers as linearly biased tracers of the matter density distribution, convolved with their Voigt profiles and integrated over the column density distribution function. We recommend the use of this model over existing models used in data analysis, which approximate the damping wings as top-hats and so miss shape information in the extended wings. The simple 'linear Voigt model' is statistically consistent with our simulation results for a mock residual contamination up to small scales ($|k| < 1\,h\,\mathrm{Mpc}^{-1}$). It does not account for the effect of the highest column density absorbers on the smallest scales (e.g., $|k| > 0.4\,h\,\mathrm{Mpc}^{-1}$ for small damped Lyman-alpha absorbers; HCD absorbers with $N(\mathrm{HI}) \sim 10^{21}\,\mathrm{atoms}\,\mathrm{cm}^{-2}$). However, these systems are in any case preferentially removed from survey data. Our model is appropriate for an accurate analysis of the baryon acoustic oscillations feature. It is additionally essential for reconstructing the full shape of the 3D flux power spectrum.Comment: 13 pages, 11 figures. Minor changes to match version published in MNRA

Dos formas de analizar un proceso de estudio sobre medida

El análisis didáctico de procesos de estudio recientemente ha sido objeto de investigación tanto en la didáctica de las matemáticas como en la de las ciencias. Dada la heterogeneidad de las metodologías que se han propuesto es pertinente identificar diferencias y semejanzas entre ellas de manera que se posibiliten propuestas integradoras. En este trabajo presentamos una propuesta integradora de dos metodologías de análisis de procesos de estudio en aulas de ciencias y de matemáticas: 1) el modelo de Scott y Mortimer para el análisis de las interacciones y la producción de significado en las clases de ciencias y 2) El modelo de análisis didáctico propuesto por el Enfoque Ontosemiótico de la cognición e instrucción matemática. Como contexto de reflexión se utiliza una clase en la que se explican unidades de medida

An Emulator for the Lyman-alpha Forest

We present methods for interpolating between the 1-D flux power spectrum of the Lyman-$\alpha$ forest, as output by cosmological hydrodynamic simulations. Interpolation is necessary for cosmological parameter estimation due to the limited number of simulations possible. We construct an emulator for the Lyman-$\alpha$ forest flux power spectrum from $21$ small simulations using Latin hypercube sampling and Gaussian process interpolation. We show that this emulator has a typical accuracy of 1.5% and a worst-case accuracy of 4%, which compares well to the current statistical error of 3 - 5% at $z < 3$ from BOSS DR9. We compare to the previous state of the art, quadratic polynomial interpolation. The Latin hypercube samples the entire volume of parameter space, while quadratic polynomial emulation samples only lower-dimensional subspaces. The Gaussian process provides an estimate of the emulation error and we show using test simulations that this estimate is reasonable. We construct a likelihood function and use it to show that the posterior constraints generated using the emulator are unbiased. We show that our Gaussian process emulator has lower emulation error than quadratic polynomial interpolation and thus produces tighter posterior confidence intervals, which will be essential for future Lyman-$\alpha$ surveys such as DESI.Comment: 28 pages, 10 figures, accepted to JCAP with minor change

Simulating the effect of high column density absorbers on the one-dimensional Lyman-alpha forest flux power spectrum

We measure the effect of high column density absorbing systems of neutral hydrogen (HI) on the one-dimensional (1D) Lyman-alpha forest flux power spectrum using cosmological hydrodynamical simulations from the Illustris project. High column density absorbers (which we define to be those with HI column densities $N(\mathrm{HI}) > 1.6 \times 10^{17}\,\mathrm{atoms}\,\mathrm{cm}^{-2}$) cause broadened absorption lines with characteristic damping wings. These damping wings bias the 1D Lyman-alpha forest flux power spectrum by causing absorption in quasar spectra away from the location of the absorber itself. We investigate the effect of high column density absorbers on the Lyman-alpha forest using hydrodynamical simulations for the first time. We provide templates as a function of column density and redshift, allowing the flexibility to accurately model residual contamination, i.e., if an analysis selectively clips out the largest damping wings. This flexibility will improve cosmological parameter estimation, e.g., allowing more accurate measurement of the shape of the power spectrum, with implications for cosmological models containing massive neutrinos or a running of the spectral index. We provide fitting functions to reproduce these results so that they can be incorporated straightforwardly into a data analysis pipeline.Comment: 11 pages, 6 figures. Minor changes to match version published in MNRA

Los riesgos geológicos en la Ordenación Territorial

There are wide areas of the planet where the incidence of natural catastrophes is very high, particularly in areas with high population density or where areas under natural risks are occupied. Most of these areas belong to a clear tectonic setting.In addition, public awareness on these natural catastrophic phenomenon acquires nowadays an additional dimension due to the important role of mass media. Mass media informs immediately al1 over the world on these caastrophes, for example, the big earthquakes (Mexico, California, Japan), landslides, floods, eruptions, hurricanes, etc.These geological phenomena are caused by the normal processes within the earth's crust, which have social and economic consequences. These processes have shaped our planet,with more or less dramatic consequences depending on their speed and intensity.Catastrophic events are gauged by their environmental effects, mainly on the biosphere. Socioeconomic disasters have also augmented as the increase and concentration of population have increased the risk on populated areas.Finally, the necessity of preventive measures is clear on global risks, such as the effects of global warming of those resulting from the management of water resources.

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