AGRIBUSINESS' RESPONSE TO GLOBALIZATION: THE MEXICAN EXPERIENCE

International Relations/Trade,

Capacity and Price Competition in Markets with Congestion Effects

We study oligopolistic competition in service markets where firms offer a service to customers. The service quality of a firm - from the perspective of a customer - depends on the congestion and the charged price. A firm can set a price for the service offered and additionally decides on the service capacity in order to mitigate congestion. The total profit of a firm is derived from the gained revenue minus the capacity investment cost. Firms simultaneously set capacities and prices in order to maximize their profit and customers subsequently choose the services with lowest combined cost (congestion and price). For this basic model, Johari et al. (2010) derived the first existence and uniqueness results of pure Nash equilibria (PNE) assuming mild conditions on congestion functions. Their existence proof relies on Kakutani's fixed-point theorem and a key assumption for the theorem to work is that demand for service is elastic (modeled by a smooth and strictly decreasing inverse demand function). In this paper, we consider the case of perfectly inelastic demand, i.e. there is a fixed volume of customers requesting service. This scenario applies to realistic cases where customers are not willing to drop out of the market, e.g. if prices are regulated by reasonable price caps. We investigate existence, uniqueness and quality of PNE for models with inelastic demand and price caps. We show that for linear congestion cost functions, there exists a PNE. This result requires a completely new proof approach compared to previous approaches, since the best response correspondences of firms may be empty, thus standard fixed-point arguments are not directly applicable. We show that the game is C-secure (see McLennan et al. (2011)), which leads to the existence of PNE. We furthermore show that the PNE is unique, and that the efficiency compared to a social optimum is unbounded in general.Comment: A one-page abstract of this paper appeared in the proceedings of the 15th International Conference on Web and Internet Economics (WINE 2019

„Je parle pas l'allemand. Mais je compare en français“: LehrerInnenperspektiven auf Sprachvergleiche

This article focuses on the method of interlinguistic comparisons in the third language acquisition from the subjective perspective of language teachers. On the basis of interviews with teachers, who teach English as a second foreign language after German in the French-speaking part of Switzerland, we analyse their experience with this method, their estimation of its effects on learning, as well as potential obstacles that may prevent teachers from making interlinguistic comparisons in the EFL-classroom. In contrast to what has been claimed in (scientific) publications on the topic, we could observe that it does not (only) depend on attitudes if teachers use multilingual pedagogical approaches, but also on their individual linguistic resources.Dieser Beitrag befasst sich mit der Methode der Sprachvergleiche im Tertiärsprachenunterricht aus der subjektiven Perspektive von Fremdsprachenlehrpersonen. Anhand von Interviews mit Lehrkräften, die in der französischen Schweiz Englisch nach Deutsch als zweite Fremdsprache unterrichten, werden ihre Erfahrungen mit der Methode, ihre Haltung hinsichtlich deren Sinnhaftigkeit sowie mögliche Hindernisse für deren Umsetzung herausgearbeitet. Entgegen der häufig in der Literatur zu findenden Aussage, dass es sich (nur) um eine Haltungsfrage handelt, ob Lehrkräfte mehrsprachigkeitsdidaktische Prinzipien umsetzen, konnten wir feststellen, dass es auch eine Frage der individuellen sprachlichen Ressourcen ist

Asymmetric desymmetrization of meso-diols by C(2)-symmetric chiral 4-pyrrolidinopyridines.

In this work we developed C(2)-symmetric chiral nucleophilic catalysts which possess a pyrrolidinopyridine framework as a catalytic site. Some of these organocatalysts effectively promoted asymmetric desymmetrization of meso-diols via enantioselective acylation

Solar hydrogen evolution using metal-free photocatalytic polymeric carbon nitride/CuInS2 composites as photocathodes

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Polymeric carbon nitride (g-C3N4) films were synthesized on polycrystalline semiconductor CuInS2 chalcopyrite thin film electrodes by thermal polycondensation and were investigated as photocathodes for the hydrogen evolution reaction (HER) under photoelectrochemical conditions. The composite photocathode materials were compared to g-C3N4 powders and were characterized with grazing incidence X-ray diffraction and X-ray photoemission spectroscopy as well as Fourier transform infrared and Raman spectroscopies. Surface modification of polycrystalline CuInS2 semiconducting thin films with photocatalytically active g-C3N4 films revealed structural and chemical properties corresponding to the properties of g-C3N4 powders. The g-C3N4/CuInS2 composite photocathode material generates a cathodic photocurrent at potentials up to +0.36 V vs. RHE in 0.1 M H2SO4 aqueous solution (pH 1), which corresponds to a +0.15 V higher onset potential of cathodic photocurrent than the unmodified CuInS2 semiconducting thin film photocathodes. The cathodic photocurrent for the modified composite photocathode materials was reduced by almost 60% at the hydrogen redox potential. However, the photocurrent generated from the g-C3N4/CuInS2 composite electrode was stable for 22 h. Therefore, the presence of the polymeric g-C3N4 films composed of a network of nanoporous crystallites strongly protects the CuInS2 semiconducting substrate from degradation and photocorrosion under acidic conditions. Conversion of visible light to hydrogen by photoelectrochemical water splitting can thus be successfully achieved by g-C3N4 films synthesized on polycrystalline CuInS2 chalcopyrite electrodes.BMBF, 03IS2071D, Light2Hydroge

Optimized immobilization of ZnO:Co electrocatalysts realizes 5% efficiency in photoassisted splitting of water

Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.Correction: There is an error in Fig. 8 of the manuscript. The correct Fig. 8 is shown in the additional file. To cite the Correction refer to DOI:10.1039/c6ta90030e.Organic solvents with varied electrophoretic mobility have been employed for deposition of nanocrystalline ZnO: Co particles onto fluorinated tin oxide supports. Evaluation of the electrochemical activity for the oxygen evolution reaction proves a clear solvent-dependence with highest activity upon deposition from acetonitrile and lowest activity upon deposition from ethanol. Analysis of the resulting layer thickness and density attributes the improved electrochemical activity of acetonitrile-prepared samples to larger film thicknesses with lower film densities, i.e. to films with higher porosity. The findings suggest that the ZnO: Co films represent an initially nanocrystalline system where the catalytic activity is predominantly confined to a thin surface region rather than to comprise the entire volume. Closer inspection of this surface region proves successive in operando transformation of the nanocrystalline to an amorphous phase during evolution of oxygen. Furthermore, less active but highly transparent ZnO: Co phases, prepared from ethanol-containing suspensions, can be successfully employed in a stacking configuration with a low-cost triple-junction solar cell. Thereby, a solar-to-hydrogen efficiency of 5.0% in splitting of water at pH 14 could be realized. In contrast, highly light-absorbing acetonitrile/acetone-prepared samples limit the efficiency to about 1%, demonstrating thus the decisive influence of the used organic solvent upon electrophoretic deposition. Stability investigations over several days finally prove that the modular architecture, applied here, represents an attractive approach for coupling of highly active electrocatalysts with efficient photovoltaic devices.BMBF, 03IS2071F, Light2Hydrogen - Energien für die ZukunftDFG, SPP 1613, Regenerativ erzeugte Brennstoffe durch lichtgetriebene Wasserspaltung: Aufklärung der Elementarprozesse und Umsetzungsperspektiven auf technologische Konzept

An optical quasimonomer

A comprehensive investigation of the luminescent properties of carbon nitride polymers, based on tri-s-triazine units, has been conducted. Steady-state temperature- and excitation-power-dependent as well as time-resolved measurements with near-UV excitation (λ=325 nm and 405 nm) yield strong photoluminescence, covering the visible spectrum. The spectral, thermal, and temporal features of the photoluminescence can be satisfactorily described by the excitation and radiative recombination of molecular excitons, localized at single tri-s-triazine units. The discussed model is in accordance with the recently reported absorption features of carbon nitride polymers. Thus, from the point of view of optical spectroscopy, the material effectively behaves as a monomer

Unifying candidate gene and GWAS Approaches in Asthma.

The first genome wide association study (GWAS) for childhood asthma identified a novel major susceptibility locus on chromosome 17q21 harboring the ORMDL3 gene, but the role of previous asthma candidate genes was not specifically analyzed in this GWAS. We systematically identified 89 SNPs in 14 candidate genes previously associated with asthma in >3 independent study populations. We re-genotyped 39 SNPs in these genes not covered by GWAS performed in 703 asthmatics and 658 reference children. Genotyping data were compared to imputation data derived from Illumina HumanHap300 chip genotyping. Results were combined to analyze 566 SNPs covering all 14 candidate gene loci. Genotyped polymorphisms in ADAM33, GSTP1 and VDR showed effects with p-values <0.0035 (corrected for multiple testing). Combining genotyping and imputation, polymorphisms in DPP10, EDN1, IL12B, IL13, IL4, IL4R and TNF showed associations at a significance level between p = 0.05 and p = 0.0035. These data indicate that (a) GWAS coverage is insufficient for many asthma candidate genes, (b) imputation based on these data is reliable but incomplete, and (c) SNPs in three previously identified asthma candidate genes replicate in our GWAS population with significance after correction for multiple testing in 14 genes

Crystal structure of polymeric carbon nitride and the determination of its process-temperature-induced modifications

Based on the arrangement of two-dimensional 'melon', we construct a unit cell for polymeric carbon nitride (PCN) synthesized via thermal polycondensation, whose theoretical diffraction powder pattern includes all major features measured in x-ray diffraction. With the help of this unit cell, we describe the process-temperature-induced crystallographic changes in PCN that occur within a temperature interval between 510 and 610 °C. We also discuss further potential modifications of the unit cell for PCN. It is found that both triazine- and heptazine-based g-C3N4 can only account for minor phases within the investigated synthesis products