Equations of state and stability of MgSiO3_3 perovskite and post-perovskite phases from quantum Monte Carlo simulations

We have performed quantum Monte Carlo (QMC) simulations and density functional theory (DFT) calculations to study the equations of state of MgSiO$_3$ perovskite (Pv) and post-perovskite (PPv), up to the pressure and temperature conditions of the base of Earth's lower mantle. The ground state energies were derived using QMC and the temperature dependent Helmholtz free energies were calculated within the quasi-harmonic approximation and density functional perturbation theory. The equations of state for both phases of MgSiO$_3$ agree well with experiments, and better than those from generalized gradient approximation (GGA) calculations. The Pv-PPv phase boundary calculated from our QMC equations of states is also consistent with experiments, and better than previous LDA calculations. We discuss the implications for double crossing of the Pv-PPv boundary in the Earth

Rocky core solubility in Jupiter and giant exoplanets

Gas giants are believed to form by the accretion of hydrogen-helium gas around an initial protocore of rock and ice. The question of whether the rocky parts of the core dissolve into the fluid H-He layers following formation has significant implications for planetary structure and evolution. Here we use ab initio calculations to study rock solubility in fluid hydrogen, choosing MgO as a representative example of planetary rocky materials, and find MgO to be highly soluble in H for temperatures in excess of approximately 10000 K, implying significant redistribution of rocky core material in Jupiter and larger exoplanets

Mixed neutron-star-plus-wormhole systems: Equilibrium configurations

We study gravitationally bound, spherically symmetric equilibrium configurations consisting of ordinary (neutron-star) matter and of a phantom/ghost scalar field which provides the nontrivial topology in the system. For such mixed configurations, we show the existence of static, regular, asymptotically flat general relativistic solutions. Based on the energy approach, we discuss the stability as a function of the core density of the neutron matter for various sizes of the wormhole throat.Comment: 18 pages, 3 figures, minor corrections to content, references added, version published in PR

Multisphalerons in the Weinberg-Salam Theory

We construct multisphaleron solutions in the Weinberg-Salam theory. The multisphaleron solutions carry Chern-Simons charge $n/2$, where $n$ is an integer, counting the winding of the fields in the azimuthal angle. The well-known sphaleron has $n=1$. The multisphalerons possess axial symmetry and parity reflection symmetry. We vary the Higgs mass and the mixing angle. For small $n$ the energies of the multisphalerons are on the order of $n$ times the energy of the sphaleron and their magnetic dipole moments are on the order of $n$ times the magnetic dipole moment of the sphaleron.Comment: 18 pages, latex, 17 figures in uuencoded postscript files. THU-94/1

Static black hole solutions with axial symmetry

We construct a new class of asymptotically flat black hole solutions in Einstein-Yang-Mills and Einstein-Yang-Mills-dilaton theory. These black hole solutions are static, and they have a regular event horizon. However, they possess only axial symmetry. Like their regular counterparts, the black hole solutions are characterized by two integers, the winding number $n$ and the node number $k$ of the gauge field functions.Comment: 14 pages, including 4 postscript figures, LaTe

Stationary Black Holes with Static and Counterrotating Horizons

We show that rotating dyonic black holes with static and counterrotating horizon exist in Einstein-Maxwell-dilaton theory when the dilaton coupling constant exceeds the Kaluza-Klein value. The black holes with static horizon bifurcate from the static black holes. Their mass decreases with increasing angular momentum, their horizons are prolate.Comment: 4 pages, 6 figure

Oral and intestinal dysbiosis in Parkinson's disease.

The suspicion of an origin of Parkinson's disease (PD) at the periphery of the body and the involvement of environmental risk factors in the pathogenesis of PD have directed the attention of the scientific community towards the microbiota. The microbiota represents all the microorganisms residing both in and on a host. It plays an essential role in the physiological functioning of the host. In this article, we review the dysbiosis repeatedly demonstrated in PD and how it influences PD symptoms. Dysbiosis is associated with both motor and non-motor PD symptoms. In animal models, dysbiosis only promotes symptoms in individuals genetically susceptible to Parkinson's disease, suggesting that dysbiosis is a risk factor but not a cause of Parkinson's disease. We also review how dysbiosis contributes to the pathophysiology of PD. Dysbiosis induces numerous and complex metabolic changes, resulting in increased intestinal permeability, local and systemic inflammation, production of bacterial amyloid proteins that promote α-synuclein aggregation, as well as a decrease in short-chain fatty acid-producing bacteria that have anti-inflammatory and neuroprotective potential. In addition, we review how dysbiosis decreases the efficacy of dopaminergic treatments. We then discuss the interest of dysbiosis analysis as a biomarker of Parkinson's disease. Finally, we give an overview of how interventions modulating the gut microbiota such as dietary interventions, pro-biotics, intestinal decontamination and fecal microbiota transplantation could influence the course of PD

Kinematics of Metal-Poor Stars in the Galaxy. II. Proper Motions for a Large Non-Kinematically Selected Sample

We present a revised catalog of 2106 Galactic stars, selected without kinematic bias, and with available radial velocities, distance estimates, and metal abundances in the range 0.0 <= [Fe/H] <= -4.0. This update of the Beers and Sommer-Larsen (1995) catalog includes newly-derived homogeneous photometric distance estimates, revised radial velocities for a number of stars with recently obtained high-resolution spectra, and refined metallicities for stars originally identified in the HK objective-prism survey (which account for nearly half of the catalog) based on a recent re-calibration. A subset of 1258 stars in this catalog have available proper motions, based on measurements obtained with the Hipparcos astrometry satellite, or taken from the updated Astrographic Catalogue (AC 2000; second epoch positions from either the Hubble Space Telescope Guide Star Catalog or the Tycho Catalogue), the Yale/San Juan Southern Proper Motion (SPM) Catalog 2.0, and the Lick Northern Proper Motion (NPM1) Catalog. Our present catalog includes 388 RR Lyrae variables (182 of which are newly added), 38 variables of other types, and 1680 non-variables, with distances in the range 0.1 to 40 kpc.Comment: 31 pages, including 8 figures, to appear in AJ (June 2000), full paper with all figures embedded available at http://pluto.mtk.nao.ac.jp/people/chiba/preprint/halo4

Sequences of Einstein-Yang-Mills-Dilaton Black Holes

Einstein-Yang-Mills-dilaton theory possesses sequences of neutral static spherically symmetric black hole solutions. The solutions depend on the dilaton coupling constant $\gamma$ and on the horizon. The SU(2) solutions are labelled by the number of nodes $n$ of the single gauge field function, whereas the SO(3) solutions are labelled by the nodes $(n_1,n_2)$ of both gauge field functions. The SO(3) solutions form sequences characterized by the node structure $(j,j+n)$, where $j$ is fixed. The sequences of magnetically neutral solutions tend to magnetically charged limiting solutions. For finite $j$ the SO(3) sequences tend to magnetically charged Einstein-Yang-Mills-dilaton solutions with $j$ nodes and charge $P=\sqrt{3}$. For $j=0$ and $j \rightarrow \infty$ the SO(3) sequences tend to Einstein-Maxwell-dilaton solutions with magnetic charges $P=\sqrt{3}$ and $P=2$, respectively. The latter also represent the scaled limiting solutions of the SU(2) sequence. The convergence of the global properties of the black hole solutions, such as mass, dilaton charge and Hawking temperature, is exponential. The degree of convergence of the matter and metric functions of the black hole solutions is related to the relative location of the horizon to the nodes of the corresponding regular solutions.Comment: 71 pages, Latex2e, 29 ps-figures include

Nondegenerate Fermions in the Background of the Sphaleron Barrier

We consider level crossing in the background of the sphaleron barrier for nondegenerate fermions. The mass splitting within the fermion doublets allows only for an axially symmetric ansatz for the fermion fields. In the background of the sphaleron we solve the partial differential equations for the fermion functions. We find little angular dependence for our choice of ansatz. We therefore propose a good approximate ansatz with radial functions only. We generalize this approximate ansatz with radial functions only to fermions in the background of the sphaleron barrier and argue, that it is a good approximation there, too.Comment: LATEX, 20 pages, 11 figure