Fungal Respiratory Infections in Cystic Fibrosis (CF): Recent Progress and Future Research Agenda

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Supersymmetric AdS(4) compactifications of IIA supergravity

We derive necessary and sufficient conditions for N=1 compactifications of (massive) IIA supergravity to AdS(4) in the language of SU(3) structures. We find new solutions characterized by constant dilaton and nonzero fluxes for all form fields. All fluxes are given in terms of the geometrical data of the internal compact space. The latter is constrained to belong to a special class of half-flat manifolds.Comment: 24 pages, references adde

Non-BPS Dyons and Branes in the Dirac-Born-Infeld Theory

Non-BPS dyon solutions to D3-brane actions are constructed when one or more scalar fields describing transverse fluctuations of the brane, are considered. The picture emerging from such non-BPS configurations is analysed, in particular the response of the D-brane-string system to small perturbations.Comment: 16 pages, 4 figures, Revtex fil

On operad structures of moduli spaces and string theory

Recent algebraic structures of string theory, including homotopy Lie algebras, gravity algebras and Batalin-Vilkovisky algebras, are deduced from the topology of the moduli spaces of punctured Riemann spheres. The principal reason for these structures to appear is as simple as the following. A conformal field theory is an algebra over the operad of punctured Riemann surfaces, this operad gives rise to certain standard operads governing the three kinds of algebras, and that yields the structures of such algebras on the (physical) state space naturally.Comment: 33 pages (An elaboration of minimal area metrics and new references are added

Electronic Structure and Heavy Fermion Behavior in LiV_2O_4

First principles density functional calculations of the electronic and magnetic properties of spinel-structure LiV$_{2}$O$_{4}$ have been performed using the full potential linearized augmented planewave method. The calculations show that the electronic structure near the Fermi energy consists of a manifold of 12 bands derived from V $t_{2g}$ states, weakly hybridized with O p states. While the total width of this active manifold is approximately 2 eV, it may be roughly decomposed into two groups: high velocity bands and flatter bands, although these mix in density functional calculations. The flat bands, which are the more atomic-like lead to a high density of states and magnetic instability of local moment character. The value of the on-site exchange energy is sensitive to the exact exchange correlation parameterization used in the calculations, but is much larger than the interaction between neighboring spins, reflecting the weak coupling of the magnetic system with the high velocity bands. A scenario for the observed heavy fermion behavior is discussed in which conduction electrons in the dispersive bands are weakly scattered by local moments associated with strongly correlated electrons in the heavy bands.This is analogous to that in conventional Kondo type heavy fermions, but is unusual in that both the local moments and conduction electrons come from the same d-manifold.Comment: 6 Revtex pages, Postscript figs embedded. Revision: figure 4 replaced with a better version, showing the band character explicitel

Theory of ac electrokinetic behavior of spheroidal cell suspensions with an intrinsic dispersion

The dielectric dispersion, dielectrophoretic (DEP) and electrorotational (ER) spectra of spheroidal biological cell suspensions with an intrinsic dispersion in the constituent dielectric constants are investigated. By means of the spectral representation method, we express analytically the characteristic frequencies and dispersion strengths both for the effective dielectric constant and the Clausius-Mossotti factor (CMF). We identify four and six characteristic frequencies for the effective dielectric spectra and CMF respectively, all of them being dependent on the depolarization factor (or the cell shape). The analytical results allow us to examine the effects of the cell shape, the dispersion strength and the intrinsic frequency on the dielectric dispersion, DEP and ER spectra. Furthermore, we include the local-field effects due to the mutual interactions between cells in a dense suspension, and study the dependence of co-field or anti-field dispersion peaks on the volume fractions.Comment: accepted by Phys. Rev.

N=1,2 supersymmetric vacua of IIA supergravity and SU(2) structures

We consider backgrounds of (massive) IIA supergravity of the form of a warped product $M_{1,3}\times_{\omega} X_6$, where $X_6$ is a six-dimensional compact manifold and $M_{1,3}$ is $AdS_4$ or a four-dimensional Minkowski space. We analyse conditions for $\mathcal{N}=1$ and $\mathcal{N}=2$ supersymmetry on manifolds of SU(2) structure. We prove the absence of solutions in certain cases.Comment: 24 pages; v2: reference adde

Three-dimensional N=8 conformal supergravity and its coupling to BLG M2-branes

This paper is concerned with the problem of coupling the N=8 superconformal Bagger-Lambert-Gustavsson (BLG) theory to N=8 conformal supergravity in three dimensions. We start by constructing the on-shell N=8 conformal supergravity in three dimensions consisting of a Chern-Simons type term for each of the gauge fields: the spin connection, the SO(8) R-symmetry gauge field and the spin 3/2 Rarita-Schwinger (gravitino) field. We then proceed to couple this theory to the BLG theory. The final theory should have the same physical content, i.e., degrees of freedom, as the ordinary BLG theory. We discuss briefly the properties of this "topologically gauged" BLG theory and why this theory may be useful.Comment: 20 pages, v2: references and comments added, presentation in section 3.2 extended. v3: misprints and a sign error corrected, version published in JHE

Multiple Intersections of D-branes and M-branes

We give a classification of all multiple intersections of D-branes in ten dimensions and M-branes in eleven dimensions that corresponds to threshold BPS bound states. The residual supersymmetry of these composite branes is determined. By dimensional reduction composite p-branes in lower dimensions can be constructed. We emphasize in dimensions D greater or equal than two, those solutions which involve a single scalar and depend on a single harmonic function. For these extremal branes we obtain the strength of the coupling between the scalar and the gauge field. In particular we give a D-brane and M-brane interpretation of extreme p-branes in two, three and four dimensions.Comment: 28 pages, LaTeX, 4 figures, corrections in table 1 and figure

Supergravity Solutions for BI Dyons

We construct partially localized supergravity counterpart solutions to the 1/2 supersymmetric non-threshold and the 1/4 supersymmetric threshold bound state BI dyons in the D3-brane Dirac-Born-Infeld theory. Such supergravity solutions have all the parameters of the BI dyons. By applying the IIA/IIB T-duality transformations to these supergravity solutions, we obtain the supergravity counterpart solutions to 1/2 and 1/4 supersymmetric BIons carrying electric and magnetic charges of the worldvolume U(1) gauge field in the Dirac-Born-Infeld theory in other dimensions.Comment: 17 pages, REVTeX, revised version to appear in Phys. Rev.