Finite gravitational action for higher derivative and stringy gravities

We generalize the local surface counterterm prescription suggested in Einstein gravity for higher derivative (HD) and Weyl gravities. Explicitly, the surface counterterm is found for three- and five-dimensional HD gravities. As a result, the gravitational action for asymptotically AdS spaces is finite and gravitational energy-momentum tensor is well-defined. The holographic trace anomaly for d2 and d4 boundary (gauge) QFT dual to above HD gravity is calculated from gravitational energy-momentum tensor. The calculation of AdS black hole mass in HD gravity is presented within above prescrition. The comparison with the standard prescription (using reference spacetime) is done.Comment: LaTeX file, 21 page

Neutrophil-initiated myocardial inflammation and Its modulation by B-type natriuretic peptide: a potential therapeutic target

Activation of neutrophils is a critically important component of the innate immune response to bacterial and chemical stimuli, and culminates in the “neutrophil burst”, which facilitates neutrophil phagocytosis via the release of superoxide anion radical (O₂-) from NADPH oxidase. Excessive and/or prolonged neutrophil activation results in substantial tissue injury and increases in vascular permeability - resulting in sustained tissue infiltration with neutrophils and monocytes, and persistent vasomotor dysfunction. Cardiovascular examples of such changes include acute and chronic systolic and diastolic heart failure (“heart failure with preserved ejection fraction”), and the catecholamine-induced inflammatory disorder takotsubo syndrome. We have recently demonstrated that B-type natriuretic peptide (BNP), acting via inhibition of activation of neutrophil NADPH oxidase, is an important negative modulator of the “neutrophil burst”, though its effectiveness in limiting tissue injury is partially lost in acute heart failure. The potential therapeutic implications of these findings, regarding the development of new means of treating both acute and chronic cardiac injury states, are discussed.Saifei Liu, Yuliy Y. Chirkov and John D. Horowit

Duality of Quasilocal Gravitational Energy and Charges with Non-orthogonal Boundaries

We study the duality of quasilocal energy and charges with non-orthogonal boundaries in the (2+1)-dimensional low-energy string theory. Quasilocal quantities shown in the previous work and some new variables arisen from considering the non-orthogonal boundaries as well are presented, and the boost relations between those quantities are discussed. Moreover, we show that the dual properties of quasilocal variables such as quasilocal energy density, momentum densities, surface stress densities, dilaton pressure densities, and Neuve-Schwarz(NS) charge density, are still valid in the moving observer's frame.Comment: 19pages, 1figure, RevTe

Levinson's Theorem for Dirac Particles

Levinson's theorem for Dirac particles constraints the sum of the phase shifts at threshold by the total number of bound states of the Dirac equation. Recently, a stronger version of Levinson's theorem has been proven in which the value of the positive- and negative-energy phase shifts are separately constrained by the number of bound states of an appropriate set of Schr\"odinger-like equations. In this work we elaborate on these ideas and show that the stronger form of Levinson's theorem relates the individual phase shifts directly to the number of bound states of the Dirac equation having an even or odd number of nodes. We use a mean-field approximation to Walecka's scalar-vector model to illustrate this stronger form of Levinson's theorem. We show that the assignment of bound states to a particular phase shift should be done, not on the basis of the sign of the bound-state energy, but rather, in terms of the nodal structure (even/odd number of nodes) of the bound state.Comment: Latex with Revtex, 7 postscript figures (available from the author), SCRI-06109

Self-consistent description of nuclear compressional modes

Isoscalar monopole and dipole compressional modes are computed for a variety of closed-shell nuclei in a relativistic random-phase approximation to three different parametrizations of the Walecka model with scalar self-interactions. Particular emphasis is placed on the role of self-consistency which by itself, and with little else, guarantees the decoupling of the spurious isoscalar-dipole strength from the physical response and the conservation of the vector current. A powerful new relation is introduced to quantify the violation of the vector current in terms of various ground-state form-factors. For the isoscalar-dipole mode two distinct regions are clearly identified: (i) a high-energy component that is sensitive to the size of the nucleus and scales with the compressibility of the model and (ii) a low-energy component that is insensitivity to the nuclear compressibility. A fairly good description of both compressional modes is obtained by using a ``soft'' parametrization having a compression modulus of K=224 MeV.Comment: 28 pages and 10 figures; submitted to PR

Medium Modification to the Ω\Omega-Meson Mass in the Walecka Model

We calculate the effective mass of the $\omega$ meson in nuclear matter in a relativistic random-phase approximation to the Walecka model. The dressing of the meson propagator is driven by its coupling to particle-hole pairs and nucleon-antinucleon ($N\bar{N}$) excitations. We report a reduction in the $\omega$-meson mass of about 170~MeV at nuclear-matter saturation density. This reduction arises from a competition between the density-dependent (particle-hole) dressing of the propagator and vacuum polarization ($N\bar{N}$ pairs). While density-dependent effects lead to an increase in the mass proportional to the classical plasma frequency, vacuum polarization leads to an even larger reduction caused by the reduced effective nucleon mass in the medium.Comment: 14 pages in ReVTeX, 3 uuencoded figures are available upon request, FSU-SCRI-93-132 and ADP-93-223/T14

The Enhancon, Black Holes, and the Second Law

We revisit the physics of five-dimensional black holes constructed from D5- and D1-branes and momentum modes in type IIB string theory compactified on K3. Since these black holes incorporate D5-branes wrapped on K3, an enhancon locus appears in the spacetime geometry. With a `small' number of D1-branes, the entropy of a black hole is maximised by including precisely half as many D5-branes as there are D1-branes in the black hole. Any attempts to introduce more D5-branes, and so reduce the entropy, are thwarted by the appearance of the enhancon locus above the horizon, which then prevents their approach. The enhancon mechanism thereby acts to uphold the Second Law of Thermodynamics. This result generalises: For each type of bound state object which can be made of both types of brane, we show that a new type of enhancon exists at successively smaller radii in the geometry, again acting to prevent any reduction of the entropy just when needed. We briefly explore the appearance of the enhancon in the black hole interior.Comment: 22 pages, 2 figures, latex, epsfig (v2: Fixed trivial typos.

The Collapse of Large Extra Dimensions

In models of spacetime that are the product of a four-dimensional spacetime with an ``extra'' dimension, there is the possibility that the extra dimension will collapse to zero size, forming a singularity. We ask whether this collapse is likely to destroy the spacetime. We argue, by an appeal to the four-dimensional cosmic censorship conjecture, that--at least in the case when the extra dimension is homogeneous--such a collapse will lead to a singularity hidden within a black string. We also construct explicit initial data for a spacetime in which such a collapse is guaranteed to occur and show how the formation of a naked singularity is likely avoided.Comment: Uses revtex

Density Dependent Hadron Field Theory

A fully covariant approach to a density dependent hadron field theory is presented. The relation between in--medium NN interactions and field--theoretical meson--nucleon vertices is discussed. The medium dependence of nuclear interactions is described by a functional dependence of the meson--nucleon vertices on the baryon field operators. As a consequence, the Euler--Lagrange equations lead to baryon rearrangement self--energies which are not obtained when only a parametric dependence of the vertices on the density is assumed. It is shown that the approach is energy--momentum conserving and thermodynamically consistent. Solutions of the field equations are studied in the mean--field approximation. Descriptions of the medium dependence in terms of the baryon scalar and vector density are investigated. Applications to infinite nuclear matter and finite nuclei are discussed. Density dependent coupling constants obtained from Dirac--Brueckner calculations with the Bonn NN-potentials are used. Results from Hartree calculations for energy spectra, binding energies and charge density distributions of $^{16}O$, $^{40,48}Ca$ and $^{208}Pb$ are presented. Comparisons to data strongly support the importance of rearrangement in a relativistic density dependent field theory. Most striking is the simultanuous improvement of charge radii, charge densities and binding energies. The results indicate the appearance of a new "Coester line" in the nuclear matter equation of state.Comment: 48 LateX pages, 12 Figures, figures and full paper are available as postscript files by anonymous ftp at ftp://theorie.physik.uni-giessen.de/dd