Excitations in the quantum paramagnetic phase of the quasi-one-dimensional Ising magnet CoNb2_2O6_6 in a transverse field: Geometric frustration and quantum renormalization effects

The quasi-one-dimensional (1D) Ising ferromagnet CoNb$_2$O$_6$ has recently been driven via applied transverse magnetic fields through a continuous quantum phase transition from spontaneous magnetic order to a quantum paramagnet, and dramatic changes were observed in the spin dynamics, characteristic of weakly perturbed 1D Ising quantum criticality. We report here extensive single-crystal inelastic neutron scattering measurements of the magnetic excitations throughout the three-dimensional (3D) Brillouin zone in the quantum paramagnetic phase just above the critical field to characterize the effects of the finite interchain couplings. In this phase, we observe that excitations have a sharp, resolution-limited line shape at low energies and over most of the dispersion bandwidth, as expected for spin-flip quasiparticles. We map the full bandwidth along the strongly dispersive chain direction and resolve clear modulations of the dispersions in the plane normal to the chains, characteristic of frustrated interchain couplings in an antiferromagnetic isosceles triangular lattice. The dispersions can be well parametrized using a linear spin-wave model that includes interchain couplings and further neighbor exchanges. The observed dispersion bandwidth along the chain direction is smaller than that predicted by a linear spin-wave model using exchange values determined at zero field, and this effect is attributed to quantum renormalization of the dispersion beyond the spin-wave approximation in fields slightly above the critical field, where quantum fluctuations are still significant.Comment: 11 pages, 6 figures. Updated references. Minor changes to text and figure

The Adapted Ordering Method for Lie Algebras and Superalgebras and their Generalizations

In 1998 the Adapted Ordering Method was developed for the representation theory of the superconformal algebras in two dimensions. It allows: to determine maximal dimensions for a given type of space of singular vectors, to identify all singular vectors by only a few coefficients, to spot subsingular vectors and to set the basis for constructing embedding diagrams. In this article we present the Adapted Ordering Method for general Lie algebras and superalgebras, and their generalizations, provided they can be triangulated. We also review briefly the results obtained for the Virasoro algebra and for the N=2 and Ramond N=1 superconformal algebras.Comment: Many improvements in the redaction for pedagogical purposes. Latex, 11 page

Adherence, satisfaction and preferences for treatment in patients with psoriasis in the European Union: a systematic review of the literature

Background and objective: Adherence to treatment in patients with psoriasis is often poor. An investigation of patient preferences and satisfaction with treatment may be important, based on the expected correlation with therapy compliance. This paper aims to examine and describe the current literature on patient preferences, satisfaction and adherence to treatment for psoriasis in the European Union (EU). Methods: Electronic searches were conducted using PubMed, ISI Web of Knowledge, Scopus, Spanish databases and Google Scholar. European studies published in English or Spanish between January 1, 2009 and December 31, 2014 regarding patient-reported outcomes in psoriatic patients were included. Studies conducted in non-EU countries, letters to the editor, editorials, experts’ opinions, case studies, congress proceedings, publications that did not differentiate between patients with psoriasis and psoriatic arthritis or studies related to specific treatment were excluded. Results: A total of 1,769 titles were identified, of which 1,636 were excluded as they were duplicates or did not provide any relevant information. After a full-text reading and application of the inclusion/exclusion criteria, 46 publications were included. This paper will describe publications on adherence (n=4), preferences (n=5) and satisfaction with treatment (n=7). Results related to health-related quality of life articles (n=30) have been published elsewhere. Adherence rates are generally low in psoriasis patients regardless of the type of treatment, severity of disease or methods used to measure adherence. Biologic therapy is associated with greater clinical improvement. There is a direct association between physician recommendations, patient preferences and several domains of treatment satisfaction. Conclusion: The results of this review support the conclusion that adherence rates in patients with psoriasis are suboptimal and highlight the need to improve patient compliance and satisfaction with treatment. Patients’ preferences should be taken into account in the treatment decision-making process in order to improve patients’ clinical outcomes by ensuring satisfaction and adherence

Giant Magnetoelectric Effect in a Multiferroic Material with a High Ferroelectric Transition Temperature

We present a unique example of giant magnetoelectric effect in a conventional multiferroic HoMnO3, where polarization is very large (~56 mC/m2) and the ferroelectric transition temperature is higher than the magnetic ordering temperature by an order. We attribute the uniqueness of the giant magnetoelectric effect to the ferroelectricity induced entirely by the off-center displacement of rare earth ions with large magnetic moments. This finding suggests a new avenue to design multiferroics with large polarization and higher ferroelectric transition temperature as well as large magnetoelectric effects

QuizMap: Open social student modeling and adaptive navigation support with TreeMaps

In this paper, we present a novel approach to integrate social adaptive navigation support for self-assessment questions with an open student model using QuizMap, a TreeMap-based interface. By exposing student model in contrast to student peers and the whole class, QuizMap attempts to provide social guidance and increase student performance. The paper explains the nature of the QuizMap approach and its implementation in the context of self-assessment questions for Java programming. It also presents the design of a semester-long classroom study that we ran to evaluate QuizMap and reports the evaluation results. © 2011 Springer-Verlag Berlin Heidelberg