Consequences of Kondo exchange on quantum spins

When individual quantum spins are placed in close proximity to conducting substrates, the localized spin is coupled to the nearby itinerant conduction electrons via Kondo exchange. In the strong coupling limit this can result in the Kondo effect — the formation of a correlated, many body singlet state — and a resulting renormalization of the density of states near the Fermi energy. However, even when Kondo screening does not occur, Kondo exchange can give rise to a wide variety of other phenomena. In addition to the well known renormalization of the g factor and the finite spin decoherence and relaxation times, Kondo exchange has recently been found to give rise to a newly discovered effect: the renormalization of the single ion magnetic anisotropy. Here we put these apparently different phenomena on equal footing by treating the effect of Kondo exchange perturbatively. In this formalism, the central quantity is ρJ, the product of the density of states at the Fermi energy ρ and the Kondo exchange constant J. We show that perturbation theory correctly describes the experimentally observed exchange induced shifts of the single spin excitation energies, demonstrating that Kondo exchange can be used to tune the effective magnetic anisotropy of a single spin.

The Gaia-ESO Survey: radial metallicity gradients and age-metallicity relation of stars in the Milky Way disk

We study the relationship between age, metallicity, and α-enhancement of FGK stars in the Galactic disk. The results are based upon the analysis of high-resolution UVES spectra from the Gaia-ESO large stellar survey. We explore the limitations of the observed dataset, i.e. the accuracy of stellar parameters and the selection effects that are caused by the photometric target preselection. We find that the colour and magnitude cuts in the survey suppress old metal-rich stars and young metal-poor stars. This suppression may be as high as 97% in some regions of the age-metallicity relationship. The dataset consists of 144 stars with a wide range of ages from 0.5 Gyr to 13.5 Gyr, Galactocentric distances from 6 kpcto 9.5 kpc, and vertical distances from the plane 0 < |Z| < 1.5 kpc. On this basis, we find that i) the observed age-metallicity relation is nearly flat in the range of ages between 0 Gyr and 8 Gyr; ii) at ages older than 9 Gyr, we see a decrease in [Fe/H] and a clear absence of metal-rich stars; this cannot be explained by the survey selection functions; iii) there is a significant scatter of [Fe/H] at any age; and iv) [Mg/Fe] increases with age, but the dispersion of [Mg/Fe] at ages >9 Gyr is not as small as advocated by some other studies. In agreement with earlier work, we find that radial abundance gradients change as a function of vertical distance from the plane. The [Mg/Fe] gradient steepens and becomes negative. In addition, we show that the inner disk is not only more α-rich compared to the outer disk, but also older, as traced independently by the ages and Mg abundances of stars.

The Gaia-ESO Survey: Empirical determination of the precision of stellar radial velocities and projected rotation velocities

Context. The Gaia-ESO Survey (GES) is a large public spectroscopic survey at the European Southern Observatory Very Large Telescope. Aims. A key aim is to provide precise radial velocities (RVs) and projected equatorial velocities (vsini) for representative samples of Galactic stars, which will complement information obtained by the Gaia astrometry satellite. Methods. We present an analysis to empirically quantify the size and distribution of uncertainties in RV and vsini using spectra from repeated exposures of the same stars. Results. We show that the uncertainties vary as simple scaling functions of signal-to-noise ratio (S/N) and vsini, that the uncertainties become larger with increasing photospheric temperature, but that the dependence on stellar gravity, metallicity and age is weak. The underlying uncertainty distributions have extended tails that are better represented by Student’s t-distributions than by normal distributions. Conclusions. Parametrised results are provided, which enable estimates of the RV precision for almost all GES measurements, and estimates of the vsini precision for stars in young clusters, as a function of S/N, vsini and stellar temperature. The precision of individual high S/N GES RV measurements is 0.22–0.26 km s-1, dependent on instrumental configuration.

Videojuegos y Educación Literaria. Narrativas transmedia en las constelaciones literarias

Actualmente, la sociedad denuncia la cada vez más acuciante desidia lectora en los estudiantes de Educación Secundaria. Es habitual escuchar que las causas de la misma se encuentran en las horas que los adolescentes dedican a la televisión, a Internet y a los videojuegos. Lejos de alimentar el rechazo a estos soportes lúdicos, este estudio se plantea que se han convertido en una parte fundamental de la cultura de los jóvenes y que, además, no solo no disuaden de la lectura, sino que están relacionados con ella y, en muchísimos casos, dependen de la misma para su propio desarrollo. No es posible imaginar un RPG (Role-Playing Game), una aventura gráfica o una visual novel sin texto escrito y es indudable que quienes emplean estos soportes están leyendo continuamente. Se plantea, pues, la posibilidad de emplear los videojuegos en el área de Didáctica de la Lengua y la Literatura como elementos viables para el desarrollo de la competencia lectoliteraria en los alumnos de Educación Secundaria, gracias a su papel como elementos transmedia y su fácil inclusión en las constelaciones literarias de cada uno de los alumnos.

Does land fragmentation affect farm performance? A case study from Brittany. Factor Markets Working Paper No. 40, April 2013

Agricultural land fragmentation is widespread and may affect farmers’ decisions and impact farm performance, either negatively or positively. The authors investigated this impact for the western region of Brittany, France, in 2007, regressing a set of performance indicators on a set of fragmentation descriptors. The performance indicators (production costs, yields, revenue, profitability, technical and scale efficiency) were calculated at the farm level using Farm Accountancy Data Network (FADN) data, while the fragmentation descriptors were calculated at the municipality level using data from the cartographic field pattern registry (RPG). The various fragmentation descriptors enabled the authors to account for not only the traditional number and average size of plots, but also their geographical scattering. They found that farms experienced higher costs of production, lower crop yields and lower profitability where land fragmentation (LF) was more pronounced. Total technical efficiency was not found to be significantly related to any of the municipality LF descriptors used, while scale efficiency was lower where the average distance to the nearest neighbouring plot was greater. Pure technical efficiency was found to be negatively related to the average number of plots in the municipality, with the unexpected result that it was also positively related to the average distance to the nearest neighbouring plot. By simulating the impact of hypothetical consolidation programmes on average pre-tax profits and wheat yield, the study also showed that the marginal benefits of reducing fragmentation may differ with respect to the improved LF dimension and the performance indicator considered. The analysis therefore shows that the measures of land fragmentation usually used in the literature do not reveal the full set of significant relationships with farm performance and that, in particular, measures accounting for distance should be considered more systematically.

Boden- und Wohnwirtschaft

Die in Kraft getretene Raumplanungsverordnung zum revidierten Raumplanungsgesetz (RPG) überlässt es den Kantonen, ob diese bei der Abschätzung ihres Rückzonungsbedarfs von einem "hohen" oder "mittleren" Szenario zur Bevölkerungsentwicklung ausgehen wollen. - Obwohl die Kantone stark mit der Umsetzung der im Vorjahr angenommenen ersten RPG-Teilrevision beschäftigt waren, schickte der Bundesrat bereits eine Vorlage zur zweiten Revisionsetappe in die Vernehmlassung. - Der Ständerat befasste sich als Erstrat mit der Botschaft zur Umsetzung der Zweitwohnungsinitiative und reizte gemäss der zuständigen Bundesrätin den gesetzgeberischen Spielraum aus. - Das Parlament verzichtet definitiv auf die 2008 beschlossene Aufhebung der Lex Koller. - Trotz kontroverser Vernehmlassungsantworten beschloss die Regierung, an der Pflicht zur Bekanntgabe des Vormietzinses festzuhalten und gab die Erarbeitung einer entsprechenden Mietrechtsrevision in Auftrag. - Durch Annahme einer Motion beschloss das Parlament, dass die Veräusserung von Bauland aus landwirtschaftlichem Besitz erneut der Grundstückgewinnsteuer unterliegen soll.

Reconfiguration of distribution network into islanded microgrids considering development of distributed energy resources

This paper discusses the potentiality of reconfiguring distribution networks into islanded Microgrids to reduce the network infrastructure reinforcement requirement and incorporate various dispersed energy resources. The major challenge would be properly breaking down the network and its resultant protection and automation system changes. A reconfiguration method is proposed based on allocation of distributed generation resources to fulfil this purpose, with a heuristic algorithm. Cost/reliability data is required for the next stage tasks to realise a case study of a particular network.

Review on protection issues of low-voltage distribution network with multiple powerelectronic-converter-interfaced distribution energy resources

The realisation of an eventual low-voltage (LV) Smart Grid with a complete communication infrastructure is a gradual process. During this evolution the protection scheme of distribution networks should be continuously adapted and optimised to fit the protection and cost requirements at the time. This paper aims to review practices and research around the design of an effective, adaptive and economical distribution network protection scheme. The background of this topic is introduced and potential problems are defined from conventional protection theories and new Smart Grid technologies. Challenges are identified with possible solutions defined as a pathway to the ultimate flexible and reliable LV protection systems.

Permanent magnet synchronous generator based wind power generation system fault protection schemes

The PMSG-based wind power generation system protection is presented in this paper. For large-scale systems, a voltagesource converter rectifier is included. Protection circuits for this topology are studied with simulation results for cable permanent fault conditions. These electrical protection methods are all in terms of dumping redundant energy resulting from disrupted path of power delivery. Pitch control of large-scale wind turbines are considered for effectively reducing rotor shaft overspeed. Detailed analysis and calculation of damping power and resistances are presented. Simulation results including fault overcurrent, DC-link overvoltage and wind turbine overspeed are shown to illustrate the system responses under different protection schemes to compare their application and effectiveness.

Stochastic descriptors to study the fate and potential of naive T cell clonotypes in the periphery

The population of naive T cells in the periphery is best described by determining both its T cell receptor diversity, or number of clonotypes, and the sizes of its clonal subsets. In this paper, we make use of a previously introduced mathematical model of naive T cell homeostasis, to study the fate and potential of naive T cell clonotypes in the periphery. This is achieved by the introduction of several new stochastic descriptors for a given naive T cell clonotype, such as its maximum clonal size, the time to reach this maximum, the number of proliferation events required to reach this maximum, the rate of contraction of the clonotype during its way to extinction, as well as the time to a given number of proliferation events. Our results show that two fates can be identified for the dynamics of the clonotype: extinction in the short-term if the clonotype experiences too hostile a peripheral environment, or establishment in the periphery in the long-term. In this second case the probability mass function for the maximum clonal size is bimodal, with one mode near one and the other mode far away from it. Our model also indicates that the fate of a recent thymic emigrant (RTE) during its journey in the periphery has a clear stochastic component, where the probability of extinction cannot be neglected, even in a friendly but competitive environment. On the other hand, a greater deterministic behaviour can be expected in the potential size of the clonotype seeded by the RTE in the long-term, once it escapes extinction.

Using geophysical surveys to test tracer-based storage estimates in headwater catchments

Acknowledgements The authors are grateful to Stian Bradford, Chris Gabrielli, and Julie Timms for practical and logistical assistance. The provision of transport by Iain Malcolm and Ross Glover of Marine Scotland Science was greatly appreciated. We also thank the European Research Council ERC (project GA 335910 VEWA) for funding through the VeWa project and the Leverhulme Trust for funding through PLATO (RPG-2014-016).

Continuous Dissolved Oxygen Measurements and Modelling Metabolism in Peatland Streams

Funding: This work was supported by the following sources of funding: European Research Council ERC (project GA 335910 VEWA) for funding through the VeWa project (DT); Leverhulme Trust for funding through PLATO (RPG-2014-016) (DT). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Deportes Electrónicos : A un clic de distancia

En la exposición se pretende presentar un proyecto de tesis y avances sobre la construcción de la misma. En la cual se abordan los deportes electrónicos, comprendiéndolos como un fenómeno reciente que se desarrolla con gran fuerza en la actualidad y creció exponencialmente durante los últimos años, brindando una oferta muy seductora al público juvenil principalmente que posea acceso a internet. Se utilizara a modo de ejemplo para la práctica seleccionada el género de videojuegos llamado MOBA (Multiplayer Open Battle Arena), representando al mismo con el juego League of Legends o conocido también como LOL; con la intención de reflejar como el movimiento y la dimensión lúdica cobran sentidos no contemplados en las definiciones tradicionales del deporte. El objetivo será explicar, describir y analizar la lógica estructural de estos videojuegos en red RPG-MMORPG-MOBA y su práctica, para poder contrastarla con la lógica del juego y la del deporte tradicional, junto a sus clasificaciones propias. Intentando poner en tensión dichas definiciones y clasificaciones que no contemplan a prácticas actuales como los Deportes Electrónicos

Deportes Electrónicos : A un clic de distancia

En la exposición se pretende presentar un proyecto de tesis y avances sobre la construcción de la misma. En la cual se abordan los deportes electrónicos, comprendiéndolos como un fenómeno reciente que se desarrolla con gran fuerza en la actualidad y creció exponencialmente durante los últimos años, brindando una oferta muy seductora al público juvenil principalmente que posea acceso a internet. Se utilizara a modo de ejemplo para la práctica seleccionada el género de videojuegos llamado MOBA (Multiplayer Open Battle Arena), representando al mismo con el juego League of Legends o conocido también como LOL; con la intención de reflejar como el movimiento y la dimensión lúdica cobran sentidos no contemplados en las definiciones tradicionales del deporte. El objetivo será explicar, describir y analizar la lógica estructural de estos videojuegos en red RPG-MMORPG-MOBA y su práctica, para poder contrastarla con la lógica del juego y la del deporte tradicional, junto a sus clasificaciones propias. Intentando poner en tensión dichas definiciones y clasificaciones que no contemplan a prácticas actuales como los Deportes Electrónicos