Jahn-Teller distortions and excitation energies in C60(n+)

Based on previously computed parameters for the electron-phonon couplings and the Coulomb exchange, we compute and classify the static Jahn-Teller distortions, i.e. the minima of the lowest adiabatic potential energy surface, of C60(n+), for all values of charge 1 <= n <= 9 and spin. We compute the intra-band electronic excitation energies in the different optimal geometries in the sudden approximation, and find a spread of the electronic states of roughly 1 eV. We also obtain the leading vibronic quantum corrections to the ground-state energy, equal to zero-point energy lowering due to the softening of the phonons at the adiabatic Jahn-Teller minima: these non-adiabatic corrections are so large that for 4 <= n <= 6 states of different spin symmetry turn lower than the high-spin adiabatic ground state.Comment: 19 pages, proceedings of the XVI Jahn-Teller Conference - Leuven (Be), 26/8 - 1/9 200

Re-weighting South African National Household Survey Data to create a consistent series over time: A cross entropy estimation approach

In the absence of established longitudinal panel surveys in South African, national cross-sectional household survey data are frequently used to analyse change. When these data are stacked side-byside, however, inconsistencies both in time trends and between household and person level data are found. This study uses a new set of weights calibrated to the ASSA 2003 model totals using a cross entropy estimation approach. This approach is favoured because the calculated weights are similar to the initial sample weights (and hence retain the survey design benefits) but match to a series of age-sex-race and province marginal totals that are consistent over time. The weights are publicly available for a fourteen year period between 1994 and 2007. This is a SALDRU/DataFirst Working Paper

Local causal structures, Hadamard states and the principle of local covariance in quantum field theory

In the framework of the algebraic formulation, we discuss and analyse some new features of the local structure of a real scalar quantum field theory in a strongly causal spacetime. In particular we use the properties of the exponential map to set up a local version of a bulk-to-boundary correspondence. The bulk is a suitable subset of a geodesic neighbourhood of any but fixed point p of the underlying background, while the boundary is a part of the future light cone having p as its own tip. In this regime, we provide a novel notion for the extended *-algebra of Wick polynomials on the said cone and, on the one hand, we prove that it contains the information of the bulk counterpart via an injective *-homomorphism while, on the other hand, we associate to it a distinguished state whose pull-back in the bulk is of Hadamard form. The main advantage of this point of view arises if one uses the universal properties of the exponential map and of the light cone in order to show that, for any two given backgrounds M and M' and for any two subsets of geodesic neighbourhoods of two arbitrary points, it is possible to engineer the above procedure such that the boundary extended algebras are related via a restriction homomorphism. This allows for the pull-back of boundary states in both spacetimes and, thus, to set up a machinery which permits the comparison of expectation values of local field observables in M and M'.Comment: 42 pages, xy package is used, typos corrected, clarifications adde

I’m Doing Better on My Own: Social Inhibition in Vocabulary Learning in Adults

Published: 05 June 2019Vocabulary learning is better achieved by children facing a teacher than when presented to the same teacher through video (so-called “video deficit” effect), which has significant implications for toddlers’ education. Since millions of adults also learn new vocabulary when acquiring a second language (L2), it is important to explore whether adults suffer from “video deficit” effects, as children do. In the present study, we report two experiments in which Spanish native late learners of English were involved in a vocabulary learning task. In Experiment 1, participants had to learn English (L2) labels associated to real objects. In Experiment 2, participants had to learn English (L2) and Spanish (L1) labels associated to novel objects. In both experiments, vocabulary learning was divided into three conditions: In the NoFace condition, participants were presented with the objects and their auditory labels, through video. In the Video condition, a teacher was showing the objects and uttering their names, through video. The Live condition was equivalent, except that the teacher was facing the participants in the room. Each condition was followed by a recall test. Better learning in Video compared to NoFace condition revealed that adults benefit from the teacher’s display with direct gaze, confirming the fundamental role of face display with direct gaze in social communication in adults. Interestingly, adults learned better through Video than in the Live condition. Those results were obtained in L2 vocabulary learning in both Experiments 1 and 2, and also generalized to native language in Experiment 2. We argue that adults suffer from social inhibition, meaning that they perform worse when in the presence of another person during task performance. In sum, we show that video-mediated teaching might not be detrimental for adults learning new vocabulary lists, as it is the case for young children. These results might have important implications for pedagogical programs targeting adults’ second language vocabulary learning, since proper acquisition of vocabulary list can be achieved through video including a teacher’s display.This research was funded by a grant from the FP7/2007–2013 Cooperation grant agreement 613465-AThEME, an ERC grant from the European Research Council (ERC-2011-ADG-295362), grants from the Spanish Government (PSI2014-54500, PSI2015-65694, and PSI2017-82941-P), and from the Basque Government (PI_2015_1_25 and PIBA18_29)

The adoption of Bt-maize in Germany: An econometric analysis

In this study, we theoretically and empirically investigate the determinants of Bt-maize adoption in German regions. Specifically, we ask how the regulatory framework, the farm structures as well as the socio-political environment of GM expansion in Germany have influenced regional adoption rates. Following a description of the relevant legal and economic framework in Germany, we develop theoretical hypotheses concerning regional variation in Bt-maize adoption and test them econometrically with unique data at the Federal States (Länder) and County (Landkreis) level. The study provides evidence that the adoption of Bt-maize in different regions is positively affected by the amount of maize grown per farm and by the European Corn Borer (ECB) infestation rates. There is also some evidence that the Btmaize adoption is negatively affected by the activities of the anti-GMO movement and the establishment of GMO-free zones.GMO crops, Germany, panel data analysis, Crop Production/Industries, Research and Development/Tech Change/Emerging Technologies,

Hund's rule Magnetism in C60 ions?

We investigate the occurrence of Hund's rule magnetism in C60(n+-) molecular ions, by computing the ground-state spin for all charge states n from -3 to +5. The two competing interactions, electron-vibration (e-v, including Jahn Teller, favoring low spin) and electron-electron (e-e, including Hund-rule exchange, favoring high spin), are accounted for based on previously computed ab-initio coupling parameters. Treating the ion coordinates as classical, we first calculate and classify the static Jahn-Teller distorted states for all n, inclusive of both e-v and e-e effects. We then correct the adiabatic result by including the zero-point energy lowering associated with softening of vibrations at the adiabatic Jahn-Teller minima. Our overall result is that while, like in previous investigations, low-spin states prevail in negative ions, Hund's rule high spin dominates all positive C60(n+) ions. This suggests also that Hund-rule magnetism could arise in fullerene cation-based solid state compounds, particularly those involving C60(2+).Comment: 12 pages, 2 figures, epj styl

Towards GMO-free landscapes? Identifying driving factors for the establishment of cooperative GMO-free zones in Germany

Since the end of the quasi-moratorium on genetically modified organisms (GMO) in the European Union in 2004, the establishment of GMO-free zones has become an EU wide phenomenon. In contrast to other European countries, Germany follows the concept of cooperative GMO-free zones where neighbouring farmers contractually refrain from GMO cultivation. In this article, we address the question which underlying factors could account for the establishment of cooperative GMO-free zones in Germany. Drawing on the existing literature on spatial agglomeration of different farming systems and the establishment of GMO-free zones, we provide the first systematic study on driving factors for the regional formation of GMO-free zones in Germany. The empirical analysis is based on a unique data set at the federal states level for the years 2004 to 2007. We show that infestation rates with the European Corn Borer, imminent Bt maize cultivation in the near vicinity and the number of arriving tourists mainly account for the establishment of cooperative GMO-free zones. This finding is consistent with the view that it is more the overall rejection of agro-biotechnology by broad strata of the population, including stakeholders in tourism and environmental protection, than economic benefits at the farm level which make German regions establish GMO-free zones.Genetically modified organisms (GMO), GMO-free zone, econometric analysis, Germany, Agribusiness,

Size and properties of the narrow-line region in Seyfert-2 galaxies from spatially-resolved optical spectroscopy

While [OIII] narrow-band imaging is commonly used to measure the size of the narrow-line regions (NLRs) in active galactic nuclei (AGNs), it can be contaminated by emission from surrounding starbursts. Recently, we have shown that long-slit spectroscopy provides a valuable alternative approach to probe the size in terms of AGN photoionisation. Moreover, several parameters of the NLR can be directly accessed. We here apply the same methods developed and described for the Seyfert-2 galaxy NGC1386 to study the NLR of five other Seyfert-2 galaxies by using high-sensitivity spatially-resolved optical spectroscopy obtained at the VLT and the NTT. We probe the AGN-photoionisation of the NLR and thus, its ``real'' size using diagnostic line-ratio diagrams.We derive physical properties of the NLR such as reddening, ionisation parameter, electron density, and velocity as a function of distance from the nucleus. For NGC5643, the diagnostic diagrams unveil a similar transition between line ratios falling in the AGN regime and those typical for HII regions as found for NGC1386, thus determining the size of the NLR. For the other four objects, all measured line ratios fall in the AGN regime. In almost all cases, both electron density and ionisation parameter decrease with radius. Deviations from this general behaviour (such as a secondary peak) seen in both the ionisation parameter and electron density can be interpreted as signs of shocks from the interaction of a radio jet and the NLR gas. In several objects, the gaseous velocity distribution is characteristic for rotational motion in an (inclined) emission-line disk in the centre. We compare our results to those of NGC1386 and show that the latter can be considered as prototypical also for this larger sample. We discuss our findings in detail for each object.Comment: 23 pages, 41 figures, accepted for publication in A&

Manipulating electronic states at oxide interfaces using focused micro X-rays from standard lab-sources

Recently, x-ray illumination, using synchrotron radiation, has been used to manipulate defects, stimulate self-organization and to probe their structure. Here we explore a method of defect-engineering low-dimensional systems using focused laboratory-scale X-ray sources. We demonstrate an irreversible change in the conducting properties of the 2-dimensional electron gas at the interface between the complex oxide materials LaAlO3 and SrTiO3 by X-ray irradiation. The electrical resistance is monitored during exposure as the irradiated regions are driven into a high resistance state. Our results suggest attention shall be paid on electronic structure modification in X-ray spectroscopic studies and highlight large-area defect manipulation and direct device patterning as possible new fields of application for focused laboratory X-ray sources.Comment: 12 pages, 4 figure