n+1 Dimensional Gravity duals to quantum criticalities with spontaneous symmetry breaking

We reexamine the charged AdS domain wall solution to the Einstein-Abelian-Higgs model proposed by Gubser et al as holographic superconductors at quantum critical points and comment on their statement about the uniqueness of gravity solutions. We generalize their explorations from 3+1 dimensions to arbitrary $n+1$Ds and find that the $n+1\geqslant5$D charged AdS domain walls are unstable against electric perturbations.Comment: version to appear in commun. theor. phy

DESIGN, SYNTHESIS AND BIOLOGICAL EVALUATION OF INHIBITORS AGAINST BOTH HUMAN AND MOUSE MICROSOMAL PROSTAGLANDIN E\u3csub\u3e2\u3c/sub\u3e SYNTHASE-1 ENZYMES

As the principal pro-inflammatory prostanoid, prostaglandin E2 (PGE2) serves as mediator of pain and fever in inflammatory reactions. The biosynthesis of PGE2 starts from arachidonic acid (AA). Cyclooxygenase (COX)-1 and/or COX-2 converts AA to prostaglandin H2 (PGH2), and PGE2 synthases transform PGH2 to PGE2. Current mainstream approach for treating inflammation-related symptoms remains the application of traditional non-steroidal anti-inflammatory drugs (tNSAIDs) and selective COX-2 inhibitors (coxibs). As both categories shut down the biosynthesis of all downstream prostanoids, their application renders several deleterious effects including gastrointestinalulceration and cardiovascular risk. Microsomal prostaglandin E2 synthase-1 (mPGES-1) inhibitors, specifically blocking the production of inflammation-related PGE2, are expected to reduce the adverse effects while retain the anti-inflammation activity. Although several compounds have been reported, only a few have entered clinical trials and none was on the market. Particularly, most of the reported human mPGES-1 inhibitors were not active for wild-type mouse/rat mPGES-1 enzymes, which prevents using the well-established mouse/rat models of inflammation in preclinical studies. Therefore, we expect our designed inhibitors to also be potent against mouse mPGES-1 and thus is suitable for preclinical testing in wild-type mice

Laser-assisted spin-polarized transport in graphene tunnel junctions

Keldysh nonequilibrium Green's function method is utilized to study theoretically the spin polarized transport through a graphene spin valve irradiated by a monochromatic laser field. It is found that the bias dependence of the differential conductance exhibits successive peaks corresponding to the resonant tunneling through the photon-assisted sidebands. The multi photon processes originate from the combined effects of the radiation field and the graphene tunneling properties, and are shown to be substantially suppressed in a graphene spin valve which results in a decrease of the differential conductance for a high bias voltage. We also discussed the appearance of a dynamical gap around zero bias due to the radiation field. The gap width can be tuned by changing the radiation electric field strength and the frequency. This leads to a shift of the resonant peaks in the differential conductance. We also demonstrate numerically the dependencies of the radiation and spin valve effects on the parameters of the external fields and those of the electrodes. We find that the combined effects of the radiation field, the graphene, and the spin valve properties bring about an oscillatory behavior in the tunnel magnetoresistance (TMR), and this oscillatory amplitude can be changed by scanning the radiation field strength and/or the frequency.Comment: 31 pages, 5 figures, corrected version to the paper in J. Phys.: Condens. Matter 24 (2012) 26600

Single or multi-flavor Kondo effect in graphene

Based on the tight-binding formalism, we investigate the Anderson and the Kondo model for an adaom magnetic impurity above graphene. Different impurity positions are analyzed. Employing a partial wave representation we study the nature of the coupling between the impurity and the conducting electrons. The components from the two Dirac points are mixed while interacting with the impurity. Two configurations are considered explicitly: the adatom is above one atom (ADA), the other case is the adatom above the center the honeycomb (ADC). For ADA the impurity is coupled with one flavor for both A and B sublattice and both Dirac points. For ADC the impurity couples with multi-flavor states for a spinor state of the impurity. We show, explicitly for a 3d magnetic atom, $d_{z^{2}}$, ($d_{xz}$,$d_{yz}$), and ($d_{x^{2}-y^{2}}$,$d_{xy}$) couple respectively with the $\Gamma_{1}$, $\Gamma_{5} (E_{1})$, and $\Gamma_{6} (E_{2})$ representations (reps) of $C_{6v}$ group in ADC case. The basses for these reps of graphene are also derived explicitly. For ADA we calculate the Kondo temperature.Comment: 11 pages, 1 fures, 2 tables, accepted by EP