Social influence and position effects

A wide range of personal choices rely on the opinions or ratings of other individuals. This information has recently become a convenient way of simplifying the decision process. For instance, in online purchases of products and services, the possible choices or alternatives are often characterized by their position in a certain presentation order (or list) and their popularity, derived from an aggregate signal of the behavior of others. We have performed a laboratory experiment to quantify and compare popularity (or social influence) and position effects in a stylized setting of homogeneous preferences, with a small number of alternatives but considerable time constraints. Our design allows for the distinction between two phases in the decision process: (1) how agents search (i.e., not only which alternatives are analyzed but also in which order) and (2) how they ultimately choose. We find that in this process there are significant popularity and position effects. Position effects are stronger than social influence effects for predicting the searching behavior, however, social influence determines to a larger extent the actual choice. The reason is that social influence generates a double effect; it directly affects the final choice (independently on what alternative has been searched more thoroughly) and indirectly alters choice through the searching behavior which, in turn, is also affected by popularity. A novelty of our approach is that we account for personal traits and provide an individual analysis of sensitivity to both social influence and position effects. Surprisingly, we find that overconfident individuals are more influenceable, whereas other personal characteristics (e.g., gender and risk aversion) do not play a significant role in this context

The Stellar Structures around Disk Galaxies

We present a brief summary of our current results on the stellar distribution and population gradients of the resolved stars in the surroundings of ~50 nearby disk galaxies, observed with space- (Hubble & Spitzer) and ground-based telescopes (Subaru, VLT, BTA, Palomar, CFHT & INT). We examine the radial (in-plane) and vertical (extraplanar) distributions of resolved stars as a function of stellar age and metallicity by tracking changes in the color-magnitude diagram of face-on and edge-on galaxies. Our data show, that the scale length and height of a stellar population increases with age, with the oldest detected stellar populations identified at a large galactocentric radius or extraplanar height, out to typically a few kpc. In the most massive of the studied galaxies there is evidence for a break in number density and color gradients of evolved stars, which plausibly correspond to the thick disk and halo components of the galaxies. The ratio of intermediate-age to old stars in the outermost fields correlate with the gas fraction, while relative sizes of the thick-to-thin disks anticorrelate with galactic circular velocity.Comment: To appear in the proceedings for the IAUS 241 'Stellar Populations as Building Blocks of Galaxies' held in La Palma, Spain, December 10-16 200

Las comunidades escionitrófilas de Alliaria petiolata (M. Bieb.) Cavara & Grande en el sur de la Península Ibérica

Las comunidades caracterizadas por Alliaria petiolata en el sur de la Península Ibérica corresponden a la asociación Myrrhoidi nodosae-Alliarietum petiolatae (clase Galio-Urticetea). Dicha asociación presenta su óptimo en la Sierra de Ayllón (Provincia Carpetano-Ibérico-Leonesa), e irradia hacia el suroeste por los sistemas béticos (provincia corológica Bética), cambiando su composición florística y empobreciéndose en esa dirección, siguiendo los distintos sectores fitogeográficos. Estos aspectos son reflejados fielmente por tres subasociaciones y una variante: subass. smyrnietosum perfoliati (subsectores Cazorlense y Alcaracense), subass. nepetosum granatensis (sectores Nevadense y Almijaro-Granatense) y subass. ranunculetosum blepharicarpi comb. nova (subsector Torcalense), que llega de modo finícola como variante supramediterránea con Sysimbrium crassifolium al extremo suroeste de las cordilleras (sector Rondeño). Esta distribución manifiesta una vía migratoria para taxones y sintaxones orófilos y mesófilos por las montañas béticas. Además, Alliaria petiolata, por su propia autoecología, su cortejo florístico y el hábitat que precisa, es un fiel bioindicador de bosques caducifolios, riparios y de abetos, que se pueden considerar hoy día muy singulares por su carácter relicto, submediterráneo o por habitar condiciones ecológicas especiales.Plant communities with Alliaria petiolata (M. Bieb.) Cavara & Grande in the South of the Iberian Peninsula. Plant communities characterized by Alliaria petiolata in the south of de Iberian Peninsula can be included in Myrrhoidi nodosae-Alliarietum petiolatae association (Galio-Urticetea class). This association is located in Ayllon mountains (Carpetano-Ibérico-Leonesa province) and distributed towards the southwest by the Betic mountain ranges (Betic chorological province) varying its floristic composition as the association reaches the different phytogeographical sectors. These aspects are clearly defined by three subassociations and one variant: subass. smyrnietosum perfoliati (Cazorlense and Alcaracense subsectors), subass. nepetosum granatensis (Nevadense y and Almijaro-Granatense sectors) and subass. ranunculetosum blepharicarpi comb. nova (Torcalense subsector) that reaches the southwest limit of Betic ranges as a supramediterranean variant with Sisymbrium crassifolium (Rondeño sector). This distribution may indicate a migratory route for orophyllous and mesophyllous taxa and syntaxa throughout the Betic Mountains. Moreover, Alliaria petiolata is an accurate bioindicator for the undergrowth of deciduous, riparian and mixed Abies pinsapo forests considered actually remarkable because of its relict character, sub-Mediterranean phytogeographical position, or special ecological requirements

Aportaciones al conocimiento de las comunidades de Pistacia Terenbinthus L. y de Acer Monspessulanum L. en el Sur de la Península Ibérica

Se aportan nuevos datos fitosociológicos sobre los terebintales-cornicabrales béticos, con la propuesta de una nueva asociación (Phillyreo latifoliae-Pistacietum terebinthi ass. nova) que representa a las formaciones de microfanerófitos mediterráneos perennifolios integrados en Quercetalia ilicis pero dominados por algunas especies caducifolias como Pistacia terebinthus. Se define también una nueva subasociación de los quejigares bético-torcalenses (Vinco difformis-Quercetum fagineae aceretosum monspessulani subass. nova) cuyo significado fitocenológico corresponde a un enriquecimiento en especies eurosiberianas y submediterráneas de Quercetalia pubescentis, fundamentalmente debido a un incremento en la altitud y a causa de las condiciones microclimáticas del biotopo en el que se asienta dicha comunidad.Contribution to the noules of the comunities of Pistacia terebinthus and Acer monspessulanum in Southern Iberian Peninsula. New phytosociological data about winter-deciduous pistachio tree forest (Phillyreo latifoliae-Pistacietum terebinthi ass. nova) endemic of the Betica province and Mediterranean region are presented. This new association is formed quantitatively by an evergreen forest; however there might predominate deciduous species such as Pistacia terebinthus. In addition, we propose a new subassociation of maple forest into the Torcalense phytogeographical subsector (Vinco difformis-Quercetum fagineae aceretosum monspessulani subass. nova). This subassociation develops on higher areas with north exposition. These conditions enable eurosiberian and submediterranean species, which belong to the phytosociological order of Quercetalia pubescentis

Sobre las alisedas nevadenses (Sierra Nevada, Granada-Almería, España)

Se ha realizado un estudio fitosociológico sobre las alisedas (bosques de Alnus glutinosa) en Sierra Nevada (Granada-Almería, España). Para ello, se han recopilado los datos existentes en archivos históricos y en bibliografía, además de reunir inventarios bibliográficos e inventarios propios. La distribución conocida de las alisedas en Sierra Nevada está centrada en dos zonas: en la cara sur los barrancos de Poqueira y Trevélez (Granada) y en la cara norte los afluentes del río Alhama de Lugros (Granada). También existen en la Sierra Nevada almeriense (río Andarax). Tras un análisis detallado de las tablas fitosociológicas, de su fitoecología, composición florística, distribución y estructura, llegamos a la conclusión de que las alisedas de Sierra Nevada constituyen una nueva asociación que denominamos Carici camposii-Alnetum glutinosae ass. nova. Se trata de bosques caducifolios muy desarrollados, con estrato arbóreo, arbustivo y herbáceo, que se desarrollan en tramos riparios con agua permanente, sobre materiales silíceos, en el piso supramediterráneo del sector fitogeográfico Nevadense (provincia Bética). Existe una variante que habita laderas de gran inclinación con suelos rezumantes, donde las alisedas muestran mayor biomasa (altura, cobertura) y aparecen algunas especies fitoindicadoras (Geum urbanum). El análisis de la tabla sintética muestra su clara separación del resto de alisedas sur-ibéricas de Osmundo-Alnion, destacando la ausencia del bioindicador más característico de esa alianza (Osmunda regalis) en la nueva asociación.Alnus glutinosa forests in Sierra Nevada (Granada-Almeria, Spain). A phytosociological survey has been made on Alnus glutinosa forests in Sierra Nevada. Historical and bibliographical data have been compiled as well as published and new phytosociological inventories. The known distribution of Alnus glutinosa forests in Sierra Nevada is concentrated in two main zones: in the southern slope along the rivers Poqueira and Trevélez (Granada) and in the northern slope along the tributaries of the Alhama de Lugros river (Granada). They have been also inventoried in Almeria province (Andarax river). After detailed analysis of phytosociological inventories and tables as well as for the ecology, floristic composition, distribution and forest structure, we conclude that the A. glutinosa forests of Sierra Nevada represent a new association: Carici camposii-Alnetum glutinosae ass. nova. They are well developed forest with trees, shrubs, and grasses strata, appearing in river banks with permanent streams, on siliceous soils in the supramediterranean bioclimatic belt of the Nevadense phytogeographical sector (Betic province). A variant, indicated by Geum urbanum, develops in high incline slopes with permanent wet soils where A. glutinosa forests show the greatest biomass (canopy cover and height of trees). Analysis of synthetic table shows clear division from the rest of the Osmundo-Alnion south-Iberian forests, emphasizing the absence of the main indicator of the alliance (Osmunda regalis) in the new association

Spatial variability of maximum and minimum monthly temperature in Spain during 1981–2010 evaluated by correlation decay distance (CDD)

The spatial variability of monthly diurnal and nocturnal mean values of temperature in Spain has been analysed to evaluate the optimal threshold distance between neighbouring stations that make a meteorological network (in terms of stations’ density) well representative of the conterminous land of Spain. To this end, the correlation decay distance has been calculated using the highest quality monthly available temperature series (1981–2010) from AEMet (National Spanish Meteorological Agency). In the conterminous land of Spain, the distance at which couples of stations have a common variance above the selected threshold (50 %, r Pearson ~0.70) for both maximum and minimum temperature on average does not exceed 400 km, with relevant spatial and temporal differences, and in extended areas of Spain, this value is lower than 200 km. The spatial variability for minimum temperature is higher than for maximum, except in cold months when the reverse is true. Spatially, highest values are located in both diurnal and nocturnal temperatures to the southeastern coastland and lower spatial variability is found to the inland areas, and thus the spatial variability shows a clear coastland-to-inland gradient at annual and monthly scale. Monthly analyses show that the highest spatial variability in maximum and minimum temperatures occur in July and August, when radiation is maximum, and in lowland areas, (<200 m o.s.l.), which coincide with the mostly transformed landscapes, particularly by irrigation and urbanization. These results highlight local factors could play a major role on spatial variability of temperature. Being maximum and minimum temperature interstation correlation values highly variable in Spanish land, an average of threshold distance of about 200 km as a limit value for a well representative network should be recommended for climate analyses,

A new climatology of maximum and minimum temperature (1951–2010) in the Spanish mainland: a comparison between three different interpolation methods

This study presents a new climatology of monthly temperature for mainland Spain (1951–2010), performed with the highest quality and spatially dense, up-to-date monthly temperature dataset available in the study area (MOTEDAS). Three different interpolation techniques were evaluated: the Local Weighted Linear Regression (LWLR), the Regression-Kriging (RK) and the Regression-Kriging with stepwise selection (RKS), a modification of RK. The performances of the different models were evaluated by the leave-one-out validation procedure, comparing the results from the models with the original data and calculating different error measurements. The three techniques performed better for Tmax than for Tmin, and for the cold, rather than warmer months, also at lower altitude than highland areas. The best results were achieved with LWLR applied for the first time on temperatures in the Spanish mainland. This method improved the accuracy of the temperature reconstruction with respect to RK and RKS. We present a collection of Tmax and Tmin monthly charts, using the same temperature legend to prevent any visual bias in the interpretation of the results. The dataset is available upon request

USE OF SYNTHETIC TANINES DURING THE SKIN CURTITION PROCESS OF Cavia porcellus (CUY) IN FINE PELETERY

The Cavia porcellus skin (Cuy), after receiving a tanning process, using synthetic tannins, becomes a high quality leather, very suitable in the articles manufacture of high quality. Its main objective was the evaluation of different levels of synthetic tannin (6, 7, 8%) during the tanning process of guinea pig skins with hair; using 48 skins, with an average mass of 200 g each. The experimental units modeled with a Completely Random Design (DCA. Once the experimental phase was completed, it observed that the most skin tanning suitable level the guinea pig (retaining hair) is 6 % of synthetic tanning agent; it´s supported by the excellent results the tests performed. The physical resistance evaluation determined that the best tensile strength (1945.75 N/cm2) it´s reached whit 6 % of synthetic tannin and the best percentage of elongation (89.69 %) achieved with the use of 7 % of tannin (which fully meet the requirements quality the Spanish Leather Association). The most efficient sensorial characteristics obtained with 6 % of tannin: fullness 4.88; softness 4.63 and roundness 4.75 points, respectively; producing a very soft, flexible skin and above all with the fullness suitable for the fine articles manufacture. Keywords: tanning, skins, guinea pig, synthetic tannins. Resumen La piel del Cavia porcellus (Cuy), después de curtida, empleando taninos sintéticos, se convierte en un cuero de alta calidad, muy adecuado en la peletería fina. Esta investigación tuvo por objetivo fundamental la evaluación de diferentes niveles de tanino sintético (6, 7, 8 %) durante el proceso de curtición de pieles de cuyes con pelo; utilizando para ello un total de 48 pieles, con una masa promedio de 200 g cada una. Las unidades experimentales fueron modeladas con un Diseño Completamente al Azar (DCA). Una vez culminada la fase experimental, se pudo constatar que el nivel más adecuado para la curtición de la piel de cuy (conservando el pelo) es del 6 % de curtiente sintético; lo cual quedó avalado por los excelentes resultados de las pruebas practicadas. La evaluación de las resistencias físicas determinó que la mejor resistencia a la tensión (1945,75 N/cm2) se alcanzó al curtir con 6 % de tanino sintético, y el mejor porcentaje de elongación (89,69 %), se logró con la utilización de 7 % de tanino (que satisfacen completamente con las exigencias de calidad de la Asociación Española del Cuero). Las características sensoriales más eficientes fueron logradas al curtir las pieles con 6 % de tanino: llenura 4,88; blandura 4,63 y redondez 4,75 puntos, respectivamente; produciéndose una piel muy suave, flexible y sobre todo con la llenura adecuada para la confección de artículos de peletería fina. Palabras Clave: Clave: curtición, pieles, cuy, taninos sintéticos

X-ray and multi-epoch optical/UV investigations of BAL to non-BAL quasar transformations

We report on an X-ray and optical/UV study of eight Broad Absorption Line (BAL) to non-BAL transforming quasars at $z\,\approx\,$1.7-2.2 over 0.29-4.95 rest-frame years with at least three spectroscopic epochs for each quasar from the SDSS, BOSS, $Gemini$, and ARC 3.5-m telescopes. New $Chandra$ observations obtained for these objects show their values of $\alpha_{\rm ox}$ and $\Delta{\alpha}_{\rm ox}$, as well as their spectral energy distributions, are consistent with those of non-BAL quasars. Moreover, our targets have X-ray spectral shapes that are, on average, consistent with weakened absorption with an effective power-law photon index of $\Gamma_{\rm eff}\,=\,1.69^{+0.25}_{-0.25}$. The newer $Gemini$ and ARC 3.5-m spectra reveal that the BAL troughs have remained absent since the BOSS observations where the BAL disappearance was discovered. The X-ray and optical/UV results in tandem are consistent with at least the X-ray absorbing material moving out of the line-of-sight, leaving an X-ray unabsorbed non-BAL quasar. The UV absorber might have become more highly ionized (in a shielding-gas scenario) or also moved out of the line-of-sight (in a wind-clumping scenario).Comment: 14 pages, 5 figures, Accepted for publication in MNRA