Weak magnetism and the Mott-state of vanadium in superconducting Sr2VO3FeAs

We report neutron scattering data and DFT calculations of the stoichiometric iron-arsenide superconductor Sr2VO3FeAs. Rietveld refinements of neutron powder patterns confirm the ideal composition without oxygen deficiencies. Experiments with polarized neutrons prove weak magnetic ordering in the V-sublattice of Sr2VO3FeAs at ~ 45 K with a probable propagation vector q = (1/8,1/8,0). The ordered moment of ~ 0.1 muB is too small to remove the V-3d bands from the Fermi level by magnetic exchange splitting, and much smaller than predicted from a recent LDA+U study. By using DFT calculations with a GGA+EECE functional we recover the typical quasi-nested Fermi-surface even without magnetic moment. From this we suggest that the V-atoms are in a Mott-state where the electronic correlations are dominated by on-site Coulomb-repulsion which shifts the V-3d states away from the Fermi energy. Our results are consistent with photoemission data and clearly reveal that Sr2VO3FeAs is a typical iron-arsenide superconductor with quasi-nested hole- and electron-like Fermi surface sheets, and constitutes no new paradigm. We suggest that intrinsic electron-doping through V3+/V4+ mixed valence is responsible for the absence of SDW ordering.Comment: 5 pages, 5 figure

Priority significance of food security in the formation process of national state security system

Присвячена обґрунтуванню й розробленню теоретико-методологічних і методичних основ продовольчої безпеки держави. Розглянуто три аспекти трактування поняття «продовольча безпека» та запропоновано власне визначення цього терміна. Здійснено аналіз результатів самооцінки домогосподарствами доступності окремих товарів та послуг, установлено, що 8,5% українських домогосподарств відчували позбавлення у сфері харчування. При розрахунку індикаторів достатності споживання основних продовольчих продуктів населенням України, тобто визначено співвідношення між фактичним споживанням і раціональними нормами споживання. Встановлено, що фактичні рівні споживання населенням країни із більшості видів продовольства перебували нижче рекомендованих показників.This article is devoted to the reasoning and development of theoretical and methodological foundations and methodical basis of food security. The author considers three aspects of the interpretation of the concept of «food security» and offers his own definition of the term. The analysis of the results of self-esteem households’ availability of certain goods and services found that 8.5% of Ukrainian households experienced food deprivation in the area. When calculating the indicator adequacy of major food products consumption of Ukraine’s population, that is evaluating the ratio between actual consumption and rational norms of consumption it is determined that the actual level of consumption of the country with most types of food was below the recommended targets. Recommended priority areas of food complex in the context of food security of Ukraine are as follows: to ensure the effectiveness of the internal market and price regulation; promote the efficiency and competitiveness of agricultural production; protect the interests of domestic producers in foreign markets; provide direction from the sale of agricultural development in the agricultural food complex economy; activate the investment in agriculture focusing on renewal of logistics enterprises and the introduction of modern agricultural production on the basis of innovation; improve the infrastructure of agriculture; implement land reform; improve food quality; international standards are to ensure standardized production of agricultural products and the domestic market with high-quality food, protection of land and improve soil fertility etc

Memorial Reconstructions: Presence and (Re)-presentation in Carbone 14's Le Dortoir

Francois Girard’s 1991 video adaptation of Gilles Maheu and Carbone 14’s stage production Le Dortoir is a moving exploration of identity and memory that takes as its primary theme and point of departure the “man-who-remembers” desire to bring his past to unmediated presence and projects a fantasy of his desire’s fulfillment on stage, but articulates this fantasy with a view to the impossibility of its realization. The manner in which Le Dortoir insistently activates the semiotic value of ‘context’ as an operant condition of its performance suggests that identity—and the partial, fragmentary memories it re-constitutes and through which it is constituted—is inevitably mediated by representation. However, despite its demonstrably postmodern attitude toward the self and representation, Le Dortoir frequently strives to bring into focus the inherent semiotic ambiguity of its dancers’ bodies— a move which engenders in the audience an intimation of presence and works to mimetically reproduce the narrative’s ostensibly modernist preoccupation with recovery and fulfillment. Having never experienced Le Dortoir as a live performance event, but only in its remediated form, I approach the work from a problematic but potentially productive intermedial standpoint. I situate my analysis at the intersection of live performance and media studies, and the theoretical framework I rely on derives from recent developments in the former. By bringing a specifically theatrical conception of presence to bear on my mediated experience of an imaginarily reconstructed ‘live’ performance—the form and thematic preoccupations of which mark it as a potentially illuminating case study—it is my hope to extend and complicate the critical discourse on presence and absence.L’adaptation vidéo que signait François Girard en 1991 de la production théâtrale de Gilles Maheu et Carbone 14 intitulée Le Dortoir est une exploration émouvante de l’identité et de la mémoire qui a comme grand thème et point de départ le désir d’un homme qui plonge dans ses souvenirs en souhaitant faire de son passé une présence non médiatisée et qui projette sur scène le fantasme de son désir, tout en exprimant ce fantasme de façon à le rendre impossible à réaliser. La façon dont Le Dortoir active avec insistance la valeur sémiotique du « contexte » en tant que condition opérante de la performance laisse entendre que l’identité—et les souvenirs partiels, fragmentaires qu’elle reconstitue et qui la constituent—a inévitablement comme médiateur la représentation. Or, malgré son attitude évidemment postmoderne à l’endroit du soi et de la représentation, Le Dortoir cherche souvent à mettre en valeur l’ambiguïté sémiotique intrinsèque des corps des danseurs, une manœuvre qui crée chez l’auditoire le sentiment d’une présence et qui tente de reproduire par mimétisme la recherche de guérison et d’accomplissement d’un récit manifestement moderne. N’ayant jamais assisté à une représentation en direct du Dortoir, et ne connaissant que la version remédiée de la pièce, l’auteur aborde l’œuvre à partir d’une position intermodale problématique qui pour-rait tout de même être productive. Son analyse se situe au croisement de la représentation en direct et des études médiatiques, et le cadre théorique utilisé s’inspire d’éléments nouveaux en études médiatiques. En imposant une conception proprement théâtrale de la présence à son expérience médiatisée d’une représentation « en direct » reconstruite dans l’imagination—dont la forme et les préoccupations thématiques en font peut-être une étude de cas éclairante—, l’auteur souhaite complexifier le discours critique sur la présence et l’absence

Cross-Cultural Competencies in International Management Curricula: A Delphi Study of Faculty Perspectives

Colleges and universities have taken steps to add international dimensions to their business curricula and programs with which they expect to positively impact students’ cross-cultural knowledge, skills, and abilities, and prepare them to function effectively in the global arena. Since limited research had been done on identifying cross-cultural competencies that graduate business courses would produce as intended outcomes, this study was a first step to identify and reach consensus on the cross-cultural competencies considered essential for inclusion into international management curricula at the university graduate level. Specifically, this study sought to answer the following two research questions: (1) What cross-cultural competencies are currently taught in international management courses, as presented in international management textbooks adopted by the leading graduate international business programs in the United States? (2) In the opinion of the Delphi panel of experts, what cross-cultural competencies are essential for inclusion in international management curricula and teaching at the university/college graduate level? A three-phase research design was employed to carry out the purpose of the study and to provide answers to these research questions. First, the textbooks in the field of international management were identified. Second, an analysis of chapter headings and subheadings for the identified textbooks provided a basic list of content statements. Then, these content statements were converted into competencies statements and organized into seven thematic groups. In order to validate and reach consensus on the identified competencies, a modified Delphi survey was conducted. Two rounds of the Delphi technique were implemented and produced the final list of cross-cultural competencies. The experts came to consensus on 23 of the 49 competencies evaluated. The identified competencies provided a list of desired outcomes which should be incorporated into international management curricula to provide effective preparation of business students for future management positions in the global arena

Physical properties and lattice dynamics of bixbyite-type V2O3

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.Some time ago, we reported the synthesis of bixbyite-type V2O3, a new metastable polymorph of vanadium sesquioxide. Since, a number of investigations followed, dealing with different aspects like electronic and magnetic properties of the material, the deviation from ideal stoichiometry or the preparation of nanocrystals as oxygen storage material. However, most of the physical properties were only evaluated on a theoretical basis. Here, we report the lattice dynamics and physical properties of bixbyite-type V2O3 bulk material, which we acquired from physical property measurements and neutron diffraction experiments over a wide temperature range. Besides attributing different possible orientations of the magnetic moments for V1 and V2 to the identified antiferromagnetic (AFM) ground state with a Néel temperature of 38.1(5) K, we use a first order Grüneisen approximation to determine lattice-dependent parameters for the relatively stiff cubic lattice, and, amongst others identify the Debye temperature to be as low as 350 ± 65 K.DFG, 73789094, SPP 1415: Kristalline Nichtgleichgewichtsphasen - Präparation, Charakterisierung und in situ-Untersuchung der Bildungsmechanisme

Suppression of superconductivity by V-doping and possible magnetic order in Sr2VO3FeAs

Superconductivity at 33 K in Sr2VO3FeAs is completely suppressed by small amounts of V-doping in Sr2VO3[Fe0.93(+/-0.01)V0.07(+/-0.01)]As. The crystal structures and exact stoichiometries are determined by combined neutron- and x-ray powder diffraction. Sr2VO3FeAs is shown to be very sensitive to Fe/V mixing, which interferes with or even suppresses superconductivity. This inhomogeneity may be intrinsic and explains scattered reports regarding Tc and reduced superconducting phase fractions in Sr2VO3FeAs. Neutron diffraction data collected at 4 K indicates incommensurate mag- netic ordering of the V-sublattice with a propagation vector q = (0,0,0.306). This suggests strongly correlated vanadium, which does not contribute significantly to the Fermi surface of Sr2VO3FeAs.Comment: text revised, magnetic q-vector added, one reference added 4 pages, 4 figure

Magnetostrictive Neel ordering of the spin-5/2 ladder compound BaMn2O3: distortion-induced lifting of geometrical frustration

The crystal structure and the magnetism of BaMn$_2$O$_3$ have been studied by thermodynamic and by diffraction techniques using large single crystals and powders. BaMn$_2$O$_3$ is a realization of a $S = 5/2$ spin ladder as the magnetic interaction is dominant along 180$^\circ$ Mn-O-Mn bonds forming the legs and the rungs of a ladder. The temperature dependence of the magnetic susceptibility exhibits well-defined maxima for all directions proving the low-dimensional magnetic character in BaMn$_2$O$_3$. The susceptibility and powder neutron diffraction data, however, show that BaMn$_2$O$_3$ exhibits a transition to antiferromagnetic order at 184 K, in spite of a full frustration of the nearest-neighbor inter-ladder coupling in the orthorhombic high-temperature phase. This frustration is lifted by a remarkably strong monoclinic distortion which accompanies the magnetic transition.Comment: 9 pages, 8 figures, 2 tables; in V1 fig. 2 was included twice and fig. 4 was missing; this has been corrected in V