184 research outputs found
Structural, electronic and magnetic properties of SrRuO under epitaxial strain
Using density functional theory within the local spin density approximation,
structural, electronic and magnetic properties of SRO are investigated. We
examine the magnitude of the orthorhombic distortion in the ground state and
also the effects of applying epitaxial constraints, whereby the influence of
large (in the range of ) in-plane strain resulting from coherent
epitaxy, for both [001] and [110] oriented films, have been isolated and
investigated. The overall pattern of the structural relaxations reveal coherent
distortions of the oxygen octahedra network, which determine stability of the
magnetic moment on the Ru ion. The structural and magnetic parameters exhibit
substantial changes allowing us to discuss the role of symmetry and
possibilities of magneto-structural tuning of \SRO-based thin film structures.Comment: 11 page
Path Integral Treatment of Proton Transport Processes in BaZrO3
Nuclear quantum effects on proton transfer and reorientation in BaZrO3 is investigated theoretically using the ab initio path-integral molecular-dynamics simulation technique. The result demonstrates that adding quantum fluctuations has a large effect on, in particular, the transfer barrier. The corresponding rates and diffusion coefficient are evaluated using the path-centroid transition state theory. In contrast with what is found assuming classical mechanics for the nuclear motion, the reorientation step becomes rate limiting below 600 K
Cryogenic micro-calorimeters for mass spectrometric identification of neutral molecules and molecular fragments
We have systematically investigated the energy resolution of a magnetic
micro-calorimeter (MMC) for atomic and molecular projectiles at impact energies
ranging from to 150 keV. For atoms we obtained absolute energy
resolutions down to eV and relative energy resolutions
down to . We also studied in detail the MMC
energy-response function to molecular projectiles of up to mass 56 u. We have
demonstrated the capability of identifying neutral fragmentation products of
these molecules by calorimetric mass spectrometry. We have modeled the MMC
energy-response function for molecular projectiles and conclude that
backscattering is the dominant source of the energy spread at the impact
energies investigated. We have successfully demonstrated the use of a detector
absorber coating to suppress such spreads. We briefly outline the use of MMC
detectors in experiments on gas-phase collision reactions with neutral
products. Our findings are of general interest for mass spectrometric
techniques, particularly for those desiring to make neutral-particle mass
measurements
Surface Effects on Oxide Heterostructures
We report on surface effects on the electronic properties of interfaces in
epitaxial LaAlO/SrTiO heterostructures. Our results are based on
first-principles electronic structure calculations for well-relaxed multilayer
configurations, terminated by an ultrathin LaAlO surface layer. On varying
the thickness of this layer, we find that the interface conduction states are
subject to almost rigid band shifts due to a modified Fermi energy. Confirming
experimental data, the electronic properties of heterointerfaces therefore can
be tuned systematically by alterating the surface-interface distance. We expect
that this mechanism is very general and applies to most oxide heterostructures.Comment: 10 pages, 3 figures, accepted by Europhys. Let
Si-compatible candidates for high-K dielectrics with the Pbnm perovskite structure
We analyze both experimentally (where possible) and theoretically from
first-principles the dielectric tensor components and crystal structure of five
classes of Pbnm perovskites. All of these materials are believed to be stable
on silicon and are therefore promising candidates for high-K dielectrics. We
also analyze the structure of these materials with various simple models,
decompose the lattice contribution to the dielectric tensor into force constant
matrix eigenmode contributions, explore a peculiar correlation between
structural and dielectric anisotropies in these compounds and give phonon
frequencies and infrared activities of those modes that are infrared-active. We
find that CaZrO_3, SrZrO_3, LaHoO_3, and LaYO_3 are among the most promising
candidates for high-K dielectrics among the compounds we considered.Comment: 17 pages, 9 figures, 4 tables. Supplementary information:
http://link.aps.org/supplemental/10.1103/PhysRevB.82.064101 or
http://www.physics.rutgers.edu/~sinisa/highk/supp.pd
Discourse and Regulation Failures: The Ambivalent Influence of NGOs on Political Organizations
In the last decades, NGOs have become an important participant in the work of political organizations (e.g., national authorities, the EU or the UN). This development brings many opportunities and also some challenges, including discourse failure which is one of the topics discussed in this paper. We present a case study that illustrates the interdependence of discourse failure and regulations failure. We conclude that discourse failure is frequently not merely an accidental by-product, but rather, a non-intended consequence of deliberate NGOs’ campaigns. We make particular note of probable discourse failure when campaigns attempt to deal with complex issues in an environment rife with wide-spread prejudices and where the NGO’s work is transparent. In this situation, regulation failure may be consequent upon discourse failure. We present collectively binding commitments for NGOs and binding services enforced by political organizations to prevent discourse failure. In conclusion, we argue that the field of political economy can benefit from this challenging environment if it systematically researches the interdependencies between discourses and regulations.In den letzten Jahrzehnten kamen NGOs als wichtige Akteure im politischen Regelsetzungsprozess hinzu (z. B. in der EU, der UN und auch auf den nationalen Ebenen). Aus dieser Entwicklung ergeben sich für die Zivilgesellschaft vielfältige Chancen, allerdings auch einige Herausforderungen. Zu den Herausforderungen zählt unter anderem Diskursversagen, woraus häufig Regulierungsversagen resultiert. Der Beitrag präsentiert eine Fallstudie, die das Zusammenspiel aus Diskurs- und Regulierungsversagen aufzeigt. Das Beispiel illustriert, dass Diskursversagen nicht nur ein zufälliger Nebeneffekt von öffentlichen Diskursen ist, sondern eine nicht-intendierte Folge zielgerichteter Kampagnen von NGOs sein kann. Insbesondere Kampagnen, die sich mit komplexen Themen auseinandersetzen, über die es in der Öffentlichkeit weitverbreitete Vorurteile gibt, neigen zu Diskursversagen. Durch transparente Kampagnen seitens der NGOs wird dies sogar begünstigt. Zur Überwindung dieser Defizite stellt der Beitrag verschiedene Bindungsmechanismen für NGOs und Bindungsservices durch Behörden und Politik vor. Abschließend zeigt der Beitrag auf, dass die Politische Ökonomik davon profitieren kann, wenn sie systematisch das Zusammenspiel zwischen Diskurs und Regulierung erforscht
Assessing Internet addiction using the parsimonious Internet addiction components model - a preliminary study [forthcoming]
Internet usage has grown exponentially over the last decade. Research indicates that excessive Internet use can lead to symptoms associated with addiction. To date, assessment of potential Internet addiction has varied regarding populations studied and instruments used, making reliable prevalence estimations difficult. To overcome the present problems a preliminary study was conducted testing a parsimonious Internet addiction components model based on Griffiths’ addiction components (2005), including salience, mood modification, tolerance, withdrawal, conflict, and relapse. Two validated measures of Internet addiction were used (Compulsive Internet Use Scale [CIUS], Meerkerk et al., 2009, and Assessment for Internet and Computer Game Addiction Scale [AICA-S], Beutel et al., 2010) in two independent samples (ns = 3,105 and 2,257). The fit of the model was analysed using Confirmatory Factor Analysis. Results indicate that the Internet addiction components model fits the data in both samples well. The two sample/two instrument approach provides converging evidence concerning the degree to which the components model can organize the self-reported behavioural components of Internet addiction. Recommendations for future research include a more detailed assessment of tolerance as addiction component
The six most essential questions in psychiatric diagnosis: A pluralogue part 2: Issues of conservatism and pragmatism in psychiatric diagnosis
In face of the multiple controversies surrounding the DSM process in general and the development of DSM-5 in particular, we have organized a discussion around what we consider six essential questions in further work on the DSM. The six questions involve: 1) the nature of a mental disorder; 2) the definition of mental disorder; 3) the issue of whether, in the current state of psychiatric science, DSM-5 should assume a cautious, conservative posture or an assertive, transformative posture; 4) the role of pragmatic considerations in the construction of DSM-5; 5) the issue of utility of the DSM – whether DSM-III and IV have been designed more for clinicians or researchers, and how this conflict should be dealt with in the new manual; and 6) the possibility and advisability, given all the problems with DSM-III and IV, of designing a different diagnostic system. Part I of this article took up the first two questions. Part II will take up the second two questions. Question 3 deals with the question as to whether DSM-V should assume a conservative or assertive posture in making changes from DSM-IV. That question in turn breaks down into discussion of diagnoses that depend on, and aim toward, empirical, scientific validation, and diagnoses that are more value-laden and less amenable to scientific validation. Question 4 takes up the role of pragmatic consideration in a psychiatric nosology, whether the purely empirical considerations need to be tempered by considerations of practical consequence. As in Part 1 of this article, the general introduction, as well as the introductions and conclusions for the specific questions, are written by James Phillips, and the responses to commentaries are written by Allen Frances
The six most essential questions in psychiatric diagnosis: a pluralogue part 1: conceptual and definitional issues in psychiatric diagnosis
In face of the multiple controversies surrounding the DSM process in general and the development of DSM-5 in particular, we have organized a discussion around what we consider six essential questions in further work on the DSM. The six questions involve: 1) the nature of a mental disorder; 2) the definition of mental disorder; 3) the issue of whether, in the current state of psychiatric science, DSM-5 should assume a cautious, conservative posture or an assertive, transformative posture; 4) the role of pragmatic considerations in the construction of DSM-5; 5) the issue of utility of the DSM - whether DSM-III and IV have been designed more for clinicians or researchers, and how this conflict should be dealt with in the new manual; and 6) the possibility and advisability, given all the problems with DSM-III and IV, of designing a different diagnostic system. Part I of this article will take up the first two questions. With the first question, invited commentators express a range of opinion regarding the nature of psychiatric disorders, loosely divided into a realist position that the diagnostic categories represent real diseases that we can accurately name and know with our perceptual abilities, a middle, nominalist position that psychiatric disorders do exist in the real world but that our diagnostic categories are constructs that may or may not accurately represent the disorders out there, and finally a purely constructivist position that the diagnostic categories are simply constructs with no evidence of psychiatric disorders in the real world. The second question again offers a range of opinion as to how we should define a mental or psychiatric disorder, including the possibility that we should not try to formulate a definition. The general introduction, as well as the introductions and conclusions for the specific questions, are written by James Phillips, and the responses to commentaries are written by Allen Frances
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