Absolute Calibration of the Radio Astronomy Flux Density Scale at 22 to 43 GHz Using Planck

The Planck mission detected thousands of extragalactic radio sources at frequencies from 28 to 857 GHz. Planck's calibration is absolute (in the sense that it is based on the satellite's annual motion around the Sun and the temperature of the cosmic microwave background), and its beams are well characterized at sub-percent levels. Thus Planck's flux density measurements of compact sources are absolute in the same sense. We have made coordinated VLA and ATCA observations of 65 strong, unresolved Planck sources in order to transfer Planck's calibration to ground-based instruments at 22, 28, and 43 GHz. The results are compared to microwave flux density scales currently based on planetary observations. Despite the scatter introduced by the variability of many of the sources, the flux density scales are determined to 1-2% accuracy. At 28 GHz, the flux density scale used by the VLA runs 3.6% +- 1.0% below Planck values; at 43 GHz, the discrepancy increases to 6.2% +- 1.4% for both ATCA and the VLA.Comment: 16 pages, 4 figures and 4 table

The canonical 8-form on manifolds with holonomy group Spin(9)

An explicit expression of the canonical 8-form on a Riemannian manifold with a Spin(9)-structure, in terms of the nine local symmetric involutions involved, is given. The list of explicit expressions of all the canonical forms related to Berger's list of holonomy groups is thus completed. Moreover, some results on Spin(9)-structures as G-structures defined by a tensor and on the curvature tensor of the Cayley planes, are obtained

Caracterización de la estructura de las sustracciones en las que estudiantes universitarios cometen errores

La resolución correcta de las operaciones elementales es uno de los objetivos de la educación obligatoria en todo el mundo aunque no siempre se consigue (López y Sánchez, 2009). En concreto, referido a la sustracción, de los 535 estudiantes universitarios de la Universidad de Salamanca que completaron el cuestionario validado de 20 sustracciones de VanLehn (1990), sólo el 24’1% realizó correctamente todas las sustracciones (Rodríguez y Sánchez, 2015). En este trabajo se pretende analizar las características de las sustracciones en cuya resolución los estudiantes universitarios cometieron algún tipo de error

Molecules with a peptide link in protostellar shocks: a comprehensive study of L1157

Interstellar molecules with a peptide link -NH-C(=O)-, like formamide (NH$_2$CHO), acetamide (NH$_2$COCH$_3$) and isocyanic acid (HNCO) are particularly interesting for their potential role in pre-biotic chemistry. We have studied their emission in the protostellar shock regions L1157-B1 and L1157-B2, with the IRAM 30m telescope, as part of the ASAI Large Program. Analysis of the line profiles shows that the emission arises from the outflow cavities associated with B1 and B2. Molecular abundance of $\approx~(0.4-1.1)\times 10^{-8}$ and $(3.3-8.8)\times 10^{-8}$ are derived for formamide and isocyanic acid, respectively, from a simple rotational diagram analysis. Conversely, NH$_2$COCH$_3$ was not detected down to a relative abundance of a few $\leq 10^{-10}$. B1 and B2 appear to be among the richest Galactic sources of HNCO and NH$_2$CHO molecules. A tight linear correlation between their abundances is observed, suggesting that the two species are chemically related. Comparison with astrochemical models favours molecule formation on ice grain mantles, with NH$_2$CHO generated from hydrogenation of HNCO.Comment: 11 pages, 9 figures. Accepted for publication in MNRAS Main Journal. Accepted 2014 August 19, in original form 2014 July

Renormalization group approach to anisotropic superconductivity

The superconducting instability of the Fermi liquid state is investigated by considering anisotropic electron-boson couplings. Both electron-electron interactions and anisotropic electron-boson couplings are treated with a renormalization-group method that takes into account retardation effects. Considering a non-interacting circular Fermi surface, we find analytical solutions for the flow equations and derive a set of generalized Eliashberg equations. Electron-boson couplings with different momentum dependences are studied, and we find superconducting instabilities of the metallic state with competition between order parameters of different symmetries. Numerical solutions for some couplings are given to illustrate the frequency dependence of the vertices at different coupling regimes.Comment: 9 pages, 7 figures. Final version as published in Phys. Rev.

How plants inspire façades. From plants to architecture: Biomimetic principles for the development of adaptive architectural envelopes

Façades have an important role in the control of energy waste in buildings, nevertheless most of them are designed to provide static design solutions, wasting large amounts of energy to maintain the internal comfort. However, biological adaptation solutions are complex, multi-functional and highly responsive. This paper proposes a biomimetic research of the relationship that can be developed between Biology and Architecture in order to propose innovative façade design solutions. We focus on plants, because of plants, like buildings, lack of movement and remain subject to a specific location. Nevertheless, plants have adapted to the environment developing special means of interaction with changing external issues. This paper provides a methodology to create a data collection of plant adaptations and a design mapping to guide the transfer from biological principles to architectural resources, as well as two design concept cases, opening new perspectives for new possible technical solutions and showing the potential of plant adaptations to environmental conditions at a specific climate. Further step is the transformation of some design concepts into technical solutions through experiments with new technologies that include multi-material 3D printing or advances in material science