Eg versus x relation from photoluminescence and electron microprobe investigations in p-type Hg1−xCdxTe (0.35 =< x =< 0.7)

Combined photoluminescence (at 10 T 300 K) and electron microprobe investigations have been carried out with HgCdTe samples grown from the melt or from solution. By exciting the samples through metallic masks with 200 μm diameter holes fixed with respect to the sample care was taken to pick-up both characteristic X-ray radiation as well as the photoluminescence from the same sample area. The Eg versus x relation determined in this way at T = 30 K has been compared with data from the interband absorption edge by other authors

Neue empirische Befunde zur Preissetzung und zum Verbraucherverhalten im Lebensmitteleinzelhandel

There are two objectives of this article: (i) It is discussed theoretically how the dynamics of pricing decisions of multiproduct retailers can be explained. (ii) It is analyzed empirically by use of scanner data how prices are actually set and how consumers react at the point of sale to price changes and promotional activities by retailers. The empirical evidence focuses on breakfast products in general and jam and breakfast cereals in particular. Main results are the following: 1. Theory of optimal pricing by multiproduct firms suggests that direct and cross price elasticities of demand and marginal costs determine the profit-maximizing price at one point of time. Good reasons do exist additionally for multiproduct retailers to vary prices intertemporally. Sales, e.g., can be consistent with optimal intertemporal pricing. 2. Scanner data for German food retailers in the period September 1996 – June 1999 are utilized in the empirical analysis. The law of one price does not hold for individual branded foods across store types. Price dispersion varies by product. The impact of sales is high in grocery retailing; on average for 20 food categories, one product of a category was on sale every other week. 3. Promotional activities affect demand for branded products strongly, but impacts on quantities varied widely. They were above average for coffee, a storeable product, below average for fresh milk, a less storeable good. In some cases, these effects are so strong that consumers seem to buy the brand only when it is on sale. 4. In the special case of jam, prices are lowest in discounters and highest in supermarkets. The spread of prices is also lowest in discounters and highest in supermarkets. Price-elastic reactions at the point of sale was, however, a uniform pattern across all store types of grocery retailing. The strongest reaction was found in supermarkets with a price elasticity of demand of –5.09. 5. For breakfast cereals, strong reactions by consumers occur to various promotional activities. Impacts on demand were, e.g., as high as 175 % when the instruments sales, display and leaflet were combined. Sales were an important feature of promotional activities with a strong demand-increasing effect. Summing up, it can be concluded that an active price policy of grocery retailers is a crucial component of their marketing mix. This is compatible with the finding of a strong price responsiveness of consumers. The stylized fact that the price elasticity of food demand is absolutely low, may be correct for aggregate demand but is not confirmed at the store level. On the contrary: High absolute levels of the store-level price elasticity of demand are typical for branded foods.food retailing, scanner data, price policy, food demand, store-level, price elasticity, multiproduct firms, jam, breakfast cereals, Agribusiness, Demand and Price Analysis,

An MCMC study of general squark flavour mixing in the MSSM

We present an extensive study of non-minimally flavour violating (NMFV) terms in the Lagrangian of the Minimal Supersymmetric Standard Model (MSSM). We impose a variety of theoretical and experimental constraints and perform a detailed scan of the parameter space by means of a Markov Chain Monte-Carlo (MCMC) setup. This represents the first study of several non-zero flavour-violating elements within the MSSM. We present the results of the MCMC scan with a special focus on the flavour-violating parameters. Based on these results, we define benchmark scenarios for future studies of NMFV effects at the LHC.Comment: 8 pages, 3 figures. To appear in the proceedings of the European Physical Society Conference on High Energy Physics 2015 (EPS-HEP 2015), Vienna, Austria, 22nd to 29th of July 201

Floquet prethermalization in the resonantly driven Hubbard model

We demonstrate the existence of long-lived prethermalized states in the Mott insulating Hubbard model driven by periodic electric fields. These states, which also exist in the resonantly driven case with a large density of photo-induced doublons and holons, are characterized by a nonzero current and an effective temperature of the doublons and holons which depends sensitively on the driving condition. Focusing on the specific case of resonantly driven models whose effective time-independent Hamiltonian in the high-frequency driving limit corresponds to noninteracting fermions, we show that the time evolution of the double occupation can be reproduced by the effective Hamiltonian, and that the prethermalization plateaus at finite driving frequency are controlled by the next-to-leading–order correction in the high-frequency expansion of the effective Hamiltonian. We propose a numerical procedure to determine an effective Hubbard interaction that mimics the correlation effects induced by these higher-order terms

Spreading of correlations in the Falicov-Kimball model

We study dynamical properties of the one- and two-dimensional Falicov-Kimball model using lattice Monte Carlo simulations. In particular, we calculate the spreading of charge correlations in the equilibrium model and after an interaction quench. The results show a reduction of the light-cone velocity with interaction strength at low temperature, while the phase velocity increases. At higher temperature, the initial spreading is determined by the Fermi velocity of the noninteracting system and the maximum range of the correlations decreases with increasing interaction strength. Charge order correlations in the disorder potential enhance the range of the correlations. We also use the numerically exact lattice Monte Carlo results to benchmark the accuracy of equilibrium and nonequilibrium dynamical cluster approximation calculations. It is shown that the bias introduced by the mapping to a periodized cluster is substantial, and that from a numerical point of view, it is more efficient to simulate the lattice model directly

Phylogeny of the nematode genus Pristionchus and implications for biodiversity, biogeography and the evolution of hermaphroditism

<p>Abstract</p> <p>Background</p> <p>The nematode <it>Pristionchus pacificus </it>has originally been developed as a satellite organism for comparison to <it>Caenorhabditis elegans</it>. A 10X coverage of the whole genome of <it>P. pacificus </it>is available, making <it>P. pacificus </it>the first non-<it>Caenorhabditis </it>nematode with a fully sequenced genome. The macroevolutionary comparison between <it>P. pacificus </it>and <it>C. elegans </it>has been complemented by microevolutionary studies of closely related strains and species within the genus <it>Pristionchus</it>. In addition, new understanding of the biology of <it>Pristionchus </it>from field studies, demonstrating a close association with various scarab beetles and the Colorado potato beetle, supports consideration of this nematode in studies of ecosystems. In the course of field studies on four continents more than 1,200 isolates were established from 15,000 beetle specimens representing 18 <it>Pristionchus </it>species. Two remarkable features of the <it>Pristionchus </it>– beetle association are the high species specificity of the interaction and the interception of the beetle's sex communication system for host recognition by the nematodes, as suggested by chemotaxis studies. Evolutionary interpretations of differences in developmental, behavioral and ecological patterns require a phylogenetic framework of the genus <it>Pristionchus</it>.</p> <p>Results</p> <p>Here, we provide a robust phylogeny of all 18 available <it>Pristionchus </it>species based on a set of 27 ribosomal protein genes encompassing a total of 10,971 bp. The phylogenetic tree provides evidence for North American and European clades, which are embedded in a deeper clade that includes Asian species. It also indicates putative invasion events. Of the 18 <it>Pristionchus </it>species, 13 are gonochoristic and five are hermaphroditic. The phylogeny indicates that all hermaphroditic species have arisen independently within the genus <it>Pristionchus</it>.</p> <p>Conclusion</p> <p>Combined ribosomal protein cDNA data can provide the basis for reconstruction of a robust phylogenetic framework for microevolutionary and biogeographic analyses. An additional major implication of our studies is the use of <it>Pristionchus </it>for nematode biodiversity assessments. While some species are represented by more than 100 isolates, others were found less than four times. Such patterns were observed on all continents and in all phylogenetic clades indicating that species asymmetry is a widespread phenomenon, which can now be further investigated by molecular tools.</p

Sex, bugs and Haldane's rule: the nematode genus Pristionchus in the United States

BACKGROUND: The nematode Pristionchus pacificus has been developed as a satellite organism in evolutionary developmental biology for comparison to Caenorhabditis elegans. Comparative studies have revealed major differences in the regulation of developmental processes between P. pacificus and C. elegans. To place evolutionary developmental biology and the observed developmental differences between species in a comprehensive evolutionary context, such studies have to be complemented with ecological aspects. Knowledge about the ecology of the organism in question might indicate specific environmental conditions that can result in developmental adaptations and could account for species differences in development. To this end, we have started to investigate the ecology of Pristionchus nematodes. In recent field studies in Western Europe we found six Pristionchus species that are closely associated with scarab beetles and the Colorado potato beetle. This Pristionchus – beetle association provides the unique opportunity to combine research in evolutionary developmental biology with ecology. However, it remains unknown how general these findings from Europe are on a global scale. RESULTS: Here, we describe the Pristionchus species associated with scarab and Colorado potato beetles in the Eastern United States and show striking transatlantic differences and unexpected evolutionary and ecological patterns. Twohundredeighty of 285 (98%) isolates from American scarab beetles belong to five Pristionchus species, all of which are different from the European species. We describe four of them as novel Pristionchus species. The five American Pristionchus species fall into a single phylogenetic clade and have a male-female (gonochoristic) mode of reproduction, whereas the majority of European isolates are hermaphroditic. Crosses between the two most closely related species, P. aerivorus and P. pseudaerivorus n. sp., follow Haldane's rule in that heterogametic F1 males are inviable. We observed P. aerivorus and P. pseudaerivorus n. sp. coexisting on the same scarab beetle and obtained two cases of F1 hybrids from wild beetles. Finally, the Colorado potato beetle is associated with the same nematode, P. uniformis in the United States and Europe. Given the introduction of the Colorado potato beetle to Europe in 1877, our results suggest that P. uniformis was introduced together with its beetle vector. CONCLUSION: Taken together, the Pristionchus – beetle association provides a powerful tool for studying biodiversity, biogeography, speciation and species invasion on a global scale

Molecular phylogeny of beetle associated diplogastrid nematodes suggests host switching rather than nematode-beetle coevolution

<p>Abstract</p> <p>Background</p> <p>Nematodes are putatively the most species-rich animal phylum. They have various life styles and occur in a variety of habitats, ranging from free-living nematodes in aquatic or terrestrial environments to parasites of animals and plants. The rhabditid nematode <it>Caenorhabditis elegans </it>is one of the most important model organisms in modern biology. <it>Pristionchus pacificus </it>of the family of the Diplogastridae has been developed as a satellite model for comparison to <it>C. elegans</it>. The Diplogastridae, a monophyletic clade within the rhabditid nematodes, are frequently associated with beetles. How this beetle-association evolved and whether beetle-nematode coevolution occurred is still elusive. As a prerequisite to answering this question a robust phylogeny of beetle-associated Diplogastridae is needed.</p> <p>Results</p> <p>Sequences for the nuclear small subunit ribosomal RNA and for 12 ribosomal protein encoding nucleotide sequences were collected for 14 diplogastrid taxa yielding a dataset of 5996 bp of concatenated aligned sequences. A molecular phylogeny of beetle-associated diplogastrid nematodes was established by various algorithms. Robust subclades could be demonstrated embedded in a phylogenetic tree topology with short internal branches, indicating rapid ancestral divergences. Comparison of the diplogastrid phylogeny to a comprehensive beetle phylogeny revealed no major congruence and thus no evidence for a long-term coevolution.</p> <p>Conclusion</p> <p>Reconstruction of the phylogenetic history of beetle-associated Diplogastridae yields four distinct subclades, whose deep phylogenetic divergence, as indicated by short internal branch lengths, shows evidence for evolution by successions of ancient rapid radiation events. The stem species of the Diplogastridae existed at the same time period when the major radiations of the beetles occurred. Comparison of nematode and beetle phylogenies provides, however, no evidence for long-term coevolution of diplogastrid nematodes and their beetle hosts. Instead, frequent host switching is observed. The molecular phylogeny of the Diplogastridae provides a framework for further examinations of the evolution of these associations, for the study of interactions within the ecosystems, and for investigations of diplogastrid genome evolution.</p

Anwedungen und Techniken zur Analyse großer Datenbestände : Tagungsband zur AKWI-Fachtagung am 11. bis 12.09.2008 an der Hochschule Niederrhein

Mit dem Vorliegen großer Datenbestände steigen natürlich auch die Wünsche und Anforderungen zur Analyse dieser Daten. Aus diesen Gründen widmet sich die AKWI Tagung 2008 mit den hier dokumentierten Beiträgen und Diskussionen diesem Thema unter dem Titel: Herausforderungen an die Wirtschaftsinformatik: Anwendungen und Techniken zur Analyse großer Datenbestände. Mit dem analytischen Customer Relationship Management (CRM) wird von Frick und Iversen das Ziel verfolgt, die Analyse der verfügbaren Informationen für die Kundenbedürfnisse einzusetzen. Das kann beträchtlich die Qualität der Kundenbeziehungen verbessern. Es erfordert aber auch eine Weiterqualifizierung aller Beteiligten. Das Supply Chain Management (SCM) dient zur Unternehmensübergreifenden Betrachtung und Modifikation der Geschäftsprozesse. Die ständige Weiterentwicklung der Geschäftsprozesse in den Unternehmen erfordert auch permanent Anpassung bei den davon in der Supply Chain betroffenen Unternehmen. Die Erweiterung der klassischen Sichtweise der Kostenfunktion im Rahmen der Produktionsplanung um die Einfuhrzollproblematik wird von Szymanski mit einem Ansatz zur Optimierung der Supply Chain mit mathematischen Optimierungsmodellen aufgezeigt. Die Gründe dafür liegen in den immer globaleren Gegebenheiten der Beschaffungs-, Produktions- und Distributionslogistik. Für die umfangreichen Aufgaben im Umgang mit den Enterprise Ressource Planning (ERP) Systemen und deren Implementierung werden heute entsprechende Tools benötigt. Von SAP wird dafür der SAP Solution Manager angeboten. Von Frick und Lankes wird der SAP Solution Manager als ein Projektmanagement Werkzeug eingesetzt. Unternehmen jeder Größenordnung sehen sich zunehmend mit der Herausforderung konfrontiert, die betrieblichen Daten für die unterschiedlichsten Zielsetzungen zur Verfügung zu stellen. Neben den betrieblichen Anforderungen rücken hier aber auch die Änderung der Abgabenordnung (AO) und damit der Datenzugriff durch die Finanzbehörden, die Einhaltung von Compliance Richtlinien und damit das Erkennen von Unterschlagungshandlungen als auch die Bestätigung der Ordnungsmäßigkeit des Jahresabschlusses durch die Wirtschaftsprüfer immer stärker in den Fokus der digitalen Aufbereitung von Unternehmensdaten. Wirtschaftsprüfer, Interne Revisoren und Betriebsprüfer der Finanzverwaltung haben die gleichen Probleme zu bewältigen, indem sie sich mit einer gewachsenen, heterogenen und durch Firmenzukäufe und Ausgliederungen stetig ändernden IT Infrastruktur auseinander zu setzen haben. Von Herde wird ein Ansatz zur Extraktion betrieblicher Massendaten in ein analysefähiges Format, unabhängig von operativen Systemen, kostengünstig realisiert. Der Umgang mit großen Mengen von Daten, auch aus unterschiedlichen Unternehmensbereichen, einer großen Anzahl von Benutzern erfordert heute ein Data Warehouse mit konsolidierten Daten. Ohne eine ausreichende Konsolidierung, d. h. ohne eine einheitliche Darstellung der Daten, kann keine sinnvolle Auswertung erfolgen. Erst mit einem Data Warehouse können die Mitarbeiter auch erkennen, was das Unternehmen zu speziellen Fragen eigentlich alles weiß. Von Stegemerten wird aufgezeigt, wie aus einer bestehenden Unternehmensstrategie eine Strategie zum Aufbau eines Data Warehouses abgeleitet werden kann und eine Organisationsstruktur beschrieben, die diese Umsetzung gewährleistet. Die Bedeutung des Controllings wird in dem Beitrag von Frank Weymerich mit der Entwicklung eines entsprechenden Cockpits deutlich. Hier werden die für das Controlling nützlichen Informationen in einem individuell bedienbaren Cockpit für die betrieblichen Entscheider sinnvoll zusammengestellt. In allen Beiträgen werden unterschiedliche spezielle Aspekte der Analyse und Organisation großer Datenbestände aus der Sicht der Wirtschaftsinformatik mit dem ihr eigenen Blick auf die Gesamtheit aller Einflussgrößen aufgezeigt

Nonequilibrium dynamical cluster approximation study of the Falicov-Kimball model

We use a nonequilibrium implementation of the dynamical cluster approximation (DCA) to study the effect of short-range correlations on the dynamics of the two-dimensional Falicov-Kimball model after an interaction quench. As in the case of single-site dynamical mean-field theory, thermalization is absent in DCA simulations, and for quenches across the metal-insulator boundary, nearest-neighbor charge correlations in the nonthermal steady state are found to be larger than in the thermal state with identical energy. We investigate to what extent it is possible to define an effective temperature of the trapped state after a quench. Based on the ratio between the lesser and retarded Green's function, we conclude that a roughly thermal distribution is reached within the energy intervals corresponding to the momentum-patch dependent subbands of the spectral function. The effectively different chemical potentials of these distributions, however, lead to a very hot, or even negative, effective temperature in the energy intervals between these subbands