On the Critical Temperature of Non-Periodic Ising Models on Hexagonal Lattices

The critical temperature of layered Ising models on triangular and honeycomb lattices are calculated in simple, explicit form for arbitrary distribution of the couplings.Comment: to appear in Z. Phys. B., 8 pages plain TEX, 1 figure available upon reques

Zero--Temperature Quantum Phase Transition of a Two--Dimensional Ising Spin--Glass

We study the quantum transition at $T=0$ in the spin-$\frac12$ Ising spin--glass in a transverse field in two dimensions. The world line path integral representation of this model corresponds to an effective classical system in (2+1) dimensions, which we study by Monte Carlo simulations. Values of the critical exponents are estimated by a finite-size scaling analysis. We find that the dynamical exponent, $z$, and the correlation length exponent, $\nu$, are given by $z = 1.5 \pm 0.05$ and $\nu = 1.0 \pm 0.1$. Both the linear and non-linear susceptibility are found to diverge at the critical point.Comment: RevTeX 10 pages + 4 figures (appended as uuencoded, compressed tar-file), THP21-9

Random bond Ising chain in a transverse magnetic field: A finite-size scaling analysis

We investigate the zero-temperature quantum phase transition of the random bond Ising chain in a transverse magnetic field. Its critical properties are identical to those of the McCoy-Wu model, which is a classical Ising model in two dimensions with layered disorder. The latter is studied via Monte Carlo simulations and transfer matrix calculations and the critical exponents are determined with a finite-size scaling analysis. The magnetization and susceptibility obey conventional rather than activated scaling. We observe that the order parameter-- and correlation function--probability distribution show a nontrivial scaling near the critical point which implies a hierarchy of critical exponents associated with the critical behavior of the generalized correlation lengths.Comment: RevTeX 13 pages + 4 figures (appended as uuencoded compressed tar-file), THP61-9

Common trends in the critical behavior of the Ising and directed walk models

We consider layered two-dimensional Ising and directed walk models and show that the two problems are inherently related. The information about the zero-field thermodynamical properties of the Ising model is contained into the transfer matrix of the directed walk. For several hierarchical and aperiodic distributions of the couplings, critical exponents for the two problems are obtained exactly through renormalization.Comment: 4 pages, RevTeX file + 1 figure, epsf needed. To be published in PR

Orexin Receptor Antagonism, a New Sleep-Enabling Paradigm: A Proof-of-Concept Clinical Trial

Peer reviewe

Glycyrrhizin Exerts Antioxidative Effects in H5N1 Influenza A Virus-Infected Cells and Inhibits Virus Replication and Pro-Inflammatory Gene Expression

Glycyrrhizin is known to exert antiviral and anti-inflammatory effects. Here, the effects of an approved parenteral glycyrrhizin preparation (Stronger Neo-Minophafen C) were investigated on highly pathogenic influenza A H5N1 virus replication, H5N1-induced apoptosis, and H5N1-induced pro-inflammatory responses in lung epithelial (A549) cells. Therapeutic glycyrrhizin concentrations substantially inhibited H5N1-induced expression of the pro-inflammatory molecules CXCL10, interleukin 6, CCL2, and CCL5 (effective glycyrrhizin concentrations 25 to 50 µg/ml) but interfered with H5N1 replication and H5N1-induced apoptosis to a lesser extent (effective glycyrrhizin concentrations 100 µg/ml or higher). Glycyrrhizin also diminished monocyte migration towards supernatants of H5N1-infected A549 cells. The mechanism by which glycyrrhizin interferes with H5N1 replication and H5N1-induced pro-inflammatory gene expression includes inhibition of H5N1-induced formation of reactive oxygen species and (in turn) reduced activation of NFκB, JNK, and p38, redox-sensitive signalling events known to be relevant for influenza A virus replication. Therefore, glycyrrhizin may complement the arsenal of potential drugs for the treatment of H5N1 disease

Fostering team creativity: Perspective taking as key to unlocking diversity's potential

In organizations, creative work is often carried out in teams, yet the mechanisms that lead teams to perform well on creative tasks are not well understood. Drawing on previous research, we argue that reframing, defined as a switch in the frame of reference from which a problem is approached, constitutes an important process to consider in explaining creative benefits on the group level. Based on an analysis of the relevant literature on group composition and processes we identify the interplay of a group's diversity and the degree to which group members engage in perspective taking as crucial antecedents to both reframing and group level creativity. We hypothesize that perspective taking moderates the effect of functional role diversity on group creativity and that this moderation effect is mediated by reframing. Results of a group experiment manipulating both diversity and perspective taking in students groups (N=77) performing a creative task largely confirm our propositions. Perspective taking and diversity interact to predict group creativity. Furthermore, audio-video coded use of reframing in the group interaction partially mediates this moderated effect. Our results indicate the importance of perspective taking to realize the potential diverse groups hold. Accordingly, in order to increase our knowledge on how to manage diverse teams, further research of the factors conducive to perspective taking represents a promising avenue for future research