Cosmological simulations with disformally coupled symmetron fields

We investigate statistical properties of the distribution of matter at redshift zero in disformal gravity by using N-body simulations. The disformal model studied here consists of a conformally coupled symmetron field with an additional exponential disformal term. We conduct cosmological simulations to discover the impact of the new disformal terms in the matter power spectrum, halo mass function, and radial profile of the scalar field. We calculated the disformal geodesic equation and the equation of motion for the scalar field. We then implemented these equations into the N-body code ISIS, which is a modified gravity version of the code RAMSES. The presence of a conformal symmetron field increases both the power spectrum and mass function compared to standard gravity on small scales. Our main finding is that the newly added disformal terms tend to counteract these effects and can make the evolution slightly closer to standard gravity. We finally show that the disformal terms give rise to oscillations of the scalar field in the centre of the dark matter haloes.Comment: Updated version to reflect the journal accepted paper. Added one figure. 7 pages, 7 figure

El interaccionismo simbólico en educación matemática

Presentamos una síntesis de las principales características del enfoque de investigación conocido como Interaccionismo Simbólico (I.S.) a través de su posicionamiento en relación a: la noción de significado, al papel del lenguaje en el aprendizaje, la manera de entender el aprendizaje y el papel desempeñado por la negociación de los significados matemáticos (ambigüedad e interpretación). Se describen los constructos teóricos utilizados por el programa interaccionista para describir y comprender los fenómenos de la enseñanza y el aprendizaje de las matemática: dominios de experiencia subjetiva, patrones de interacción y normas sociomatemáticas. Se identifican ciertas similitudes entre algunas de los constructos teóricos en el IS y en la teoría de las situaciones didácticas y finalmente se sitúa el programa interaccionista entre el individualismo y el colectivismo en el intento por explicar el aprendizaje matemático

Temporal variation of the total nitrogen concentration in aereal organs of nitrogen fixing and non fixing riparian species

Changes in nitrogen concentration was determinated in samples of Alnus glutinosa, Elaeagnus angustifolia, Populus x canadiensis and Ailanthus altissima leaves, petioles and branches periodically during a year. Maximum nitrogen percentage was found in diazotrophic species (Alnus and Elaeagnus) and the nitrogen retranslocation form branches was higher (2.5 times) in no fixing species.Se estudian 10s cambios en la concentración de nitrógeno en Alnus glutinosa, Elaeagnus angustifolia, Populus x canadiensis y Ailanthus altissima, en hojas, peciolos y tallos periódicamente durante un año. El porcentaje máximo de nitrógeno se encuentra en las especies diazotrofas (Alnus y Elaeagnus) y la retraslocación de dicho elemento desde los tallos es superior (2.5) veces) en las plantas no actinonizas

A Spatio-Temporal Study of Ischemia and the Time-Frequency Coupling Variations between the ST Amplitude, Heart Rate and Dominant Angle

Abstract An analysis of the Long Term ST Database (LTSTDB) was conducted to quantify the spatio-temporal dynamics of ischemic and non-ischemic episodes. For all 86 recordings the ischemic episode length is decribed by a lognormal distribution and the non-ischemic episode length by a generalized extreme value distribution. For the 15 recordings that possess orthogonal (EASI) leads sets we derived the 12 standard leads and analyzed the spatial time course (from the j-point to j+120 ms) of each episode over time to identify dominant trends. Although the magnitude of the ischemic episodes did not reveal any inter-subject trend (except for generally exhibiting Brownian-like motion), there appeared to be strong correlations with the heart rate (HR). Wavelet cross-spectral coupling with significance testing was then applied to the ST-amplitude and HR evolution over the course of each episode. In all subjects significant cross-spectral correlations were found at very low frequencies (<0.04 Hz), as well as at respiration and baroreflex frequencies. This may indicate that the ischemic episodes are modulated by blood pressure and activity or HR-related phenomena and that all episodes in the LTSTDB may be of a 'mixed' type at some point in their duration. The dominant angle also showed significant correlation (p<0.01) with the ST amplitude and HR changes at similar frequencies to those described above. All three protocols used to define ischemia in the LTSTDB gave similar results. Introduction Modelling the short-and long-term spatial and temporal changes in the ECG during ischemia provides a mechanism for baseline testing of relevant signal processing algorithms. Our aim in this work was to provide a description of such changes in order to provide information to build an accurate simulation of the ECG during ischemia. Methods Data The data used in this study were taken from the LongTerm ST Database (LTSTDB) [1] available from PhysioNet which contains 21-24 hour multi-channel ECG recordings and annotated ischemic and non-ishemic ST changes. An ischemic episode was defined to start when the ST deviation exceeded a lower threshold, V lower = 50µV . Next, the deviation was required to reach or exceed an upper threshold, V upper , for at least a continuous interval of T min seconds. Finally, the episode ended when the deviation dropped to less than V lower = 50µV in the following T sep = 30 s. The values of (V upper , T min ) were (75 µV , 30 s), (100 µV , 30 s) and (100 µV , 60 s) defined as protocol STA, STB and STC respectively. All analysis was performed in the vectorcardiogram (VCG) space. The LTSTDB contains 15 recordings (s30691 through s30801) which used the EASI lead system Similarly they give the transformation from the EASI configuration to the vectorcardiogram (X, Y, Z) configuration, V , the matrix Temporal analysis of the episodes The lengths of each ischemic and non-ischemic episode for all 86 patients in the LTSTDB were calculated using all available leads. An episode was taken to start if any lead satisfied the criteria for the relevant protocol and was taken to end when all leads ceased to satisfy the same pro

Rayleigh-wave attenuation by a semi-infinite two-dimensional elastic-band-gap crystal

In this paper, we report experiments on the scattering of surface-elastic waves by a periodic array of cylindrical holes. The experiments were performed in a marble quarry by drilling cylindrical holes in two different configurations: honeycomb and triangular lattices. The attenuation spectra of the surface waves show the existence of absolute band gaps for elastic waves in these semi-infinite two-dimensional crystals. Results are compared with theoretical calculations based on a scalar-wave approach. The scaling property of the underlying theory has led us to explore the possible application of the results obtained to the attenuation of surface waves in seismic movements.This work was partially supported by the Comisión Interministerial de Ciencia y Tecnología of Spain, Contract No. MAT97-0698-C04. We also thank the Consejo Superior de Investigaciones Científicas for the special funding to perform this experiment.Peer reviewe

The slingshot effect as a probe of transverse motions of galaxies

Context: There are currently no reliable methods to measure the transverse velocities of galaxies. This is an important piece of information that is lacking in galaxy catalogues, and it could allow us to probe the physics of structure formation and to test the underlying theory of gravity. The slingshot effect (a special case of the integrated Sachs–Wolfe effect) is expected to create dipole signals in the temperature fluctuations of the cosmic microwave background (CMB) radiation. This effect creates a hot spot behind and a cold spot in front of moving massive objects. The dipole signal created by the slingshot effect can be used to measure transverse velocities, but because the signal is expected to be weak, the effect has not been measured yet. Aims: Our aim is to show that the slingshot effect can be measured by stacking the signals of galaxies falling into a collapsing cluster. Furthermore, we evaluate whether the effect can probe modified gravity. Methods: We used data from a simulated galaxy catalogue (MultiDark Planck 2) to mimic observations. We identified a 1015 M⊙ cluster, and made maps of the slingshot effect for photons passing near 8438 infalling galaxies. To emulate instrument noise, we added uncorrelated Gaussian noise to each map. We assumed that the average velocity is directed towards the centre of the cluster. The maps were rotated according to the expected direction of motion. This assures that the dipole signal adds up constructively when stacking the maps. We compared the stacked maps to a dipole stencil to determine the quality of the signal. We also evaluated the probability of fitting the stencil in the absence of the slingshot signal. Results: Each galaxy gives a signal of around ΔT/T ≈ 10−9, while the current precision of CMB experiments is ΔT/T ≈ 4 × 10−6. By stacking around 10 000 galaxies and performing a stencil fit, the slingshot signal can be over the detectable threshold with today’s experiments. However, due to the difficulty of distinguishing an actual signal from false positives, future CMB experiments must be used to be certain of the strength of the observed signal

The Effect of Cosmological Background Dynamics on the Spherical Collapse in MOND

The effect of background dynamics of the universe on formation of large scale structures in the framework of Modified Newtonian Dynamics (MOND) is investigated. A spherical collapse model is used for modeling the formation of the structures. This study is done in two extreme cases: ({\it i}) assuming a universe with a low-density baryonic matter without any cold dark matter and dark energy; ({\it ii}) a dark energy dominated universe with baryonic matter, without cold dark matter. We show that for the case ({\it ii}) the structures virialize at lower redshifts with larger radii compared to the low-density background universe. The dark energy slow downs the collapse of the structures. We show that our results are compatible with recent simulations of the structure formation in MOND.Comment: 16 pages, 4 Figures, accepted by New Astronom

An investigation into CLIL-related sections of EFL coursebooks : issues of CLIL inclusion in the publishing market

The current ELT global coursebook market has embraced CLIL as a weak form of bilingual education and an innovative component to include in General English coursebooks for EFL contexts. In this paper I investigate how CLIL is included in ELT coursebooks aimed at teenaged learners, available to teachers in Argentina. My study is based on the content analysis of four series which include a section advertised as CLIL-oriented. Results suggest that such sections are characterised by (1) little correlation between featured subject specific content and school curricula in L1, (2) oversimplification of contents, and (3) dominance of reading skills development and lower-order thinking tasks. Through this study, I argue that CLIL components become superficial supplements rather than a meaningful attempt to promote weak forms of bilingual education

Medida del emprendizaje: adaptación y validación de la escala de actitudes emprendedoras EASS en profesores españoles

The aim of this study is to offer an assessment instrument to know the entrepreneurial attitudes of the professorate or educators (EAST), adapted from the Entrepreneurial Attitudes Scale for Students (EASS), and also to provide a first approximation to diagnosis in the field of Spanish-speaking context. A cross-sectional on-line survey was carried out in a single time, in which 155 teachers participated. The new adapted instrument, based on the Entrepreneurial Attitudes Scale for Students (EASS), assesses six entrepreneurial attitudes: proactivity, professional ethics, empathy, innovation, autonomy, and risk taking that define the individual with motivation towards entrepreneurship. Confirmatory factor analysis provides appropriate results: χ2 (120) = 214.225 (p < .001), CFI = .963, TLI = .953, SRMR = .011, RMSEA = .071. Reliability estimations are also calculated, with Cronbach’s alphas ranging from .95 to .97 for the six dimensions. A negative relation regarding entrepreneurship and age is found, as well as higher levels of entrepreneurial attitudes in women than in men. Results show appropriate psychometric properties. As far as literature has been revised, the adaptation presented here is the only developed for this purpose in Spanish-speaking context so far.El objetivo de este trabajo es ofrecer un instrumento de evaluación que permita conocer las actitudes emprendedoras del profesorado, mediante la adaptación de la original Escala de Actitudes Emprendedoras para Estudiantes, al tiempo que facilitar una primera aproximación a su diagnóstico en el ámbito español, con proyección en el área de habla hispana. En el marco de un diseño transversal, se llevó a cabo una encuesta on-line en un único momento temporal en la que participaron 155 profesionales de la educación. El instrumento adaptado (Escala de Actitudes Emprendedoras para Profesores, EAST), basado en la Escala de Actitudes Emprendedoras para Estudiantes de Oliver y Galiana (2016), evalúa 6 actitudes emprendedoras con 18 ítems: proactividad, ética profesional, empatía, innovación, autonomía y toma de riesgos, que definen a la persona con motivación hacia el emprendimiento. El análisis factorial confirmatorio ofrece resultados adecuados: χ2 (120) = 214.225 (p < .001), CFI = .963, TLI = .953, SRMR = .011, RMSEA = .071. Se obtienen estimaciones de fiabilidad excelentes, con alfas de Cronbach de .95 a .97 para las seis dimensiones. Se detecta una relación negativa del emprendimiento con la edad, y una mayor presencia en mujeres. Los resultados muestran unas propiedades psicométricas adecuadas de la nueva adaptación, siendo este, hasta donde se conoce, el primero desarrollado para evaluar en educadores actitudes emprendedoras en el contexto hispano-hablante