Testing strong line metallicity diagnostics at z~2

High-z galaxy gas-phase metallicities are usually determined through observations of strong optical emission lines with calibrations tied to the local universe. Recent debate has questioned if these calibrations are valid in the high-z universe. We investigate this by analysing a sample of 16 galaxies at z~2 available in the literature, and for which the metallicity can be robustly determined using oxygen auroral lines. The sample spans a redshift range of 1.4 < z < 3.6, has metallicities of 7.4-8.4 in 12+log(O/H) and stellar masses 10^7.5-10^11 Msun. We test commonly used strong line diagnostics (R23, O3, O2, O32, N2, O3N2 and Ne3O2 ) as prescribed by four different sets of empirical calibrations, as well as one fully theoretical calibration. We find that none of the strong line diagnostics (or calibration set) tested perform consistently better than the others. Amongst the line ratios tested, R23 and O3 deliver the best results, with accuracies as good as 0.01-0.04 dex and dispersions of ~0.2 dex in two of the calibrations tested. Generally, line ratios involving nitrogen predict higher values of metallicity, while results with O32 and Ne3O2 show large dispersions. The theoretical calibration yields an accuracy of 0.06 dex, comparable to the best strong line methods. We conclude that, within the metallicity range tested in this work, the locally calibrated diagnostics can still be reliably applied at z~2.Comment: 12 pages, 8 Figures, accepted for publication in MNRA

On the detection of nearly optimal solutions in the context of single-objective space mission design problems

When making decisions, having multiple options available for a possible realization of the same project can be advantageous. One way to increase the number of interesting choices is to consider, in addition to the optimal solution x*, also nearly optimal or approximate solutions; these alternative solutions differ from x* and can be in different regions – in the design space – but fulfil certain proximity to its function value f(x*). The scope of this article is the efficient computation and discretization of the set E of e–approximate solutions for scalar optimization problems. To accomplish this task, two strategies to archive and update the data of the search procedure will be suggested and investigated. To make emphasis on data storage efficiency, a way to manage significant and insignificant parameters is also presented. Further on, differential evolution will be used together with the new archivers for the computation of E. Finally, the behaviour of the archiver, as well as the efficiency of the resulting search procedure, will be demonstrated on some academic functions as well as on three models related to space mission design

Preferences for efficiency, rather than preferences for morality, drive cooperation in the one-shot Stag-Hunt game

Recent work highlights that cooperation in the one-shot Prisoner's dilemma (PD) is primarily driven by moral preferences for doing the right thing, rather than social preferences for equity or efficiency. To our knowledge, nothing is known on whether moral preferences affect cooperation in the Stag-Hunt Game (SHG). Cooperation in the SHG fundamentally differs from cooperation in the PD in that it is not costly, but risky: players have no temptation to deviate from the cooperative outcome, but cooperation only pays off if the other player cooperates. Here we provide data from two experiments (total N = 523) to investigate SHG cooperation. Contrary to what has been observed for the PD, we find that SHG cooperation is primarily driven by preferences for efficiency, rather than moral preferences for doing the right thing

Physical processes leading to surface inhomogeneities: the case of rotation

In this lecture I discuss the bulk surface heterogeneity of rotating stars, namely gravity darkening. I especially detail the derivation of the omega-model of Espinosa Lara & Rieutord (2011), which gives the gravity darkening in early-type stars. I also discuss the problem of deriving gravity darkening in stars owning a convective envelope and in those that are members of a binary system.Comment: 23 pages, 11 figure, Lecture given to the school on the cartography of the Sun and the stars (May 2014 in Besan\c{c}on), to appear in LNP, Neiner and Rozelot edts V2: typos correcte

Anomalously strong pinning of the filling factor nu=2 in epitaxial graphene

We explore the robust quantization of the Hall resistance in epitaxial graphene grown on Si-terminated SiC. Uniquely to this system, the dominance of quantum over classical capacitance in the charge transfer between the substrate and graphene is such that Landau levels (in particular, the one at exactly zero energy) remain completely filled over an extraordinarily broad range of magnetic fields. One important implication of this pinning of the filling factor is that the system can sustain a very high nondissipative current. This makes epitaxial graphene ideally suited for quantum resistance metrology, and we have achieved a precision of 3 parts in 10^10 in the Hall resistance quantization measurements

From Informal Housing to Housing at Risk, Preliminary Diagnosis of Some Neighborhoods in Quito

In the second half of the twentieth century in Ecuador, collective housing projects undertaken by the state began to emerge, while informal settlements consolidated on the outskirts of the city. The way in which these neighborhoods were consolidated has had an impact on the quality of life of their inhabitants. By allowing them to identify natural, social, and anthropic risks, they have accentuated and conditioned the safety of users, such as hillside location, context, materiality, accessibility, mobility, infrastructure, etc. The research is based on a comparative study of risks in three neighborhoods of Quito, to understand that both the participation of the people and the cooperation of the regulating entity are important for giving rise to housing projects. Based on the method proposed by Livingston and supported by the literature and bibliographic review, we seek to identify the risks that are generated or emphasized in the different stages of housing, highlighting the importance of building an integrated city based on the inhabitants and their way of inhabiting the space. Finally, we seek to understand that in the creation of housing projects, the appropriation of space makes it possible to turn a neighborhood into a community that reflects the diverse way of living of the users. Keywords: citizen participation, social housing, informal settlements, Quito. Resumen En la segunda mitad del siglo XX en Ecuador empezaron a surgir proyectos de vivienda colectiva emprendidos por el estado central, en paralelo en la periferia de la ciudad se consolidaron asentamientos informales. La forma en la que se consolidaron estos barrios ha tenido un impacto en la calidad de vida de sus habitantes; esto ha permitido identificar riesgos naturales, sociales y antrópicos, los mismos que se han acentuado y condicionan la seguridad de los usuarios, tales como ubicación sobre laderas, contexto, materialidad, accesibilidad, movilidad, infraestructura, etc. La investigación se basa en un estudio comparativo sobre riesgos presentes en tres barrios de Quito, con el fin de entender que tanto la participación de las personas como la cooperación de la entidad reguladora, son importantes al momento de dar lugar a proyectos de vivienda. Partiendo del método propuesto por Livingston y apoyado en la revisión literaria y bibliográfica, se busca identificar los riesgos que se generan o enfatizan en las diferentes etapas de la vivienda, resaltando la importancia de construir una ciudad integrada que tiene como base a los habitantes y su forma de habitar el espacio. Finalmente, se busca entender que en la creación de proyectos habitacionales la apropiación del espacio permite convertir a un barrio en una comunidad que refleja la forma diversa de habitar de los usuarios. Palabras Clave: Participación Ciudadana, Vivienda Social, Asentamientos Informales, Quito

Radio Spectra of Giant Radio Galaxies from RATAN-600 Data

Measurements of the flux densities of the extended components of seven giant radio galaxies obtained using the RATAN-600 radio telescope at wavelengths of 6.25 and 13 cm ar e presented. The spectra of components of these radio galaxies are constructed using these new RA TAN-600 data together with data from the WENSS, NVSS, and GB6 surveys. The spectral indices in the stu died frequency range are calculated, and the need for detailed estimates of the integrated contributi on of such objects to the background emission is demonstrated.Comment: 7 pages, 2 figures, 5 table

Stabilizing All Geometric Moduli in Heterotic Calabi-Yau Vacua

We propose a scenario to stabilize all geometric moduli - that is, the complex structure, Kahler moduli and the dilaton - in smooth heterotic Calabi-Yau compactifications without Neveu-Schwarz three-form flux. This is accomplished using the gauge bundle required in any heterotic compactification, whose perturbative effects on the moduli are combined with non-perturbative corrections. We argue that, for appropriate gauge bundles, all complex structure and a large number of other moduli can be perturbatively stabilized - in the most restrictive case, leaving only one combination of Kahler moduli and the dilaton as a flat direction. At this stage, the remaining moduli space consists of Minkowski vacua. That is, the perturbative superpotential vanishes in the vacuum without the necessity to fine-tune flux. Finally, we incorporate non-perturbative effects such as gaugino condensation and/or instantons. These are strongly constrained by the anomalous U(1) symmetries which arise from the required bundle constructions. We present a specific example, with a consistent choice of non-perturbative effects, where all remaining flat directions are stabilized in an AdS vacuum.Comment: 24 pages, 2 figure

Non-Abelian phases, charge pumping, and quantum computation with Josephson junctions

Non-Abelian geometric phases can be generated and detected in certain superconducting nanocircuits. Here we consider an example where the holonomies are related to the adiabatic charge dynamics of the Josephson network. We demonstrate that such a device can be applied both for adiabatic charge pumping and as an implementation of a quantum computer.Comment: 11 pages RevTex, 3 figures in eps format, revised versio