Equilibrium evaporation coefficients quantified as transmission probabilities for monatomic fluids

Equilibrium molecular dynamics (MD) simulations are used to investigate the liquid/vapor interface where particleexchange between the liquid and vapor phase is quantified in terms of the evaporation and condensation coefficient.The coefficients are extracted from MD simulations via a particle counting procedure. This requires defining avapor boundary position for which we introduce an accurate and robust method and present a comparative studywith existing methods from the literature. This novel method relies on the behavior of the flux coefficient withinthe interphase region by scanning the position of a particle sink boundary from the liquid towards the vaporphase. We find a distinct local maxima is attained on the vapor side of the interphase that is identified as thevapor boundary position based on an interpretation of transmission probability theory and the Kullback-Leiblerdivergence. The ratio of the evaporation flux to the outgoing flux at this location is defined as the evaporationcoefficient. This method retains the simplicity of existing methods but eliminates several disadvantages. We applythis method to MD simulations of monatomic fluids neon, argon, krypton and xenon. We observe a correlationbetween the molecular transport parameter appearing in transmission probability theory and the characteristicinterface fluctuation length scale from capillary wave theory. This gives an expression for the evaporation coefficientthat agrees well with values extracted from MD using the particle counting procedure. Compared to existingmethods, the evaporation/condensation coefficient is determined more accurately for temperatures between thetriple and critical points.Equilibrium molecular dynamics (MD) simulations are used to investigate the liquid/vapor interface where particle exchange between the liquid and vapor phase is quantified in terms of the evaporation and condensation coefficient. The coefficients are extracted from MD simulations via a particle counting procedure. This requires defining a vapor boundary position for which we introduce an accurate and robust method and present a comparative study with existing methods from the literature. This novel method relies on the behavior of the flux coefficient within the interphase region by scanning the position of a particle sink boundary from the liquid toward the vapor phase. We find a distinct local maxima is attained on the vapor side of the interphase that is identified as the vapor boundary position based on an interpretation of transmission probability theory and the Kullback–Leibler divergence. The ratio of the evaporation flux to the outgoing flux at this location is defined as the evaporation coefficient. This method retains the simplicity of existing methods but eliminates several disadvantages. We apply this method to MD simulations of monatomic fluids neon, argon, krypton, and xenon. We observe a correlation between the molecular transport parameter appearing in the transmission probability theory and the characteristic interface fluctuation length scale from the capillary wave theory. This gives an expression for the evaporation coefficient that agrees well with values extracted from MD using the particle counting procedure. Compared to existing methods, the evaporation/condensation coefficient is determined more accurately for temperatures between the triple and critical points

Measuring black-hole parameters and testing general relativity using gravitational-wave data from space-based interferometers

Among the expected sources of gravitational waves for the Laser Interferometer Space Antenna (LISA) is the capture of solar-mass compact stars by massive black holes residing in galactic centers. We construct a simple model for such a capture, in which the compact star moves freely on a circular orbit in the equatorial plane of the massive black hole. We consider the gravitational waves emitted during the late stages of orbital evolution, shortly before the orbiting mass reaches the innermost stable circular orbit. We construct a simple model for the gravitational-wave signal, in which the phasing of the waves plays the dominant role. The signal's behavior depends on a number of parameters, including $\mu$, the mass of the orbiting star, $M$, the mass of the central black hole, and $J$, the black hole's angular momentum. We calculate, using our simplified model, and in the limit of large signal-to-noise ratio, the accuracy with which these quantities can be estimated during a gravitational-wave measurement. Our simplified model also suggests a method for experimentally testing the strong-field predictions of general relativity.Comment: ReVTeX, 16 pages, 5 postscript figure

Heavy quark action on the anisotropic lattice

We investigate the $O(a)$ improved quark action on anisotropic lattice as a potential framework for the heavy quark, which may enable precision computation of hadronic matrix elements of heavy-light mesons. The relativity relations of heavy-light mesons as well as of heavy quarkonium are examined on a quenched lattice with spatial lattice cutoff $a_\sigma^{-1} \simeq$ 1.6 GeV and the anisotropy $\xi=4$. We find that the bare anisotropy parameter tuned for the massless quark describes both the heavy-heavy and heavy-light mesons within 2% accuracy for the quark mass $a_\sigma m_Q < 0.8$, which covers the charm quark mass. This bare anisotropy parameter also successfully describes the heavy-light mesons in the quark mass region $a_\sigma m_Q \leq 1.2$ within the same accuracy. Beyond this region, the discretization effects seem to grow gradually. The anisotropic lattice is expected to extend by a factor $\xi$ the quark mass region in which the parameters in the action tuned for the massless limit are applicable for heavy-light systems with well controlled systematic errors.Comment: 11 pages, REVTeX4, 11 eps figure

Evolution of circular, non-equatorial orbits of Kerr black holes due to gravitational-wave emission: II. Inspiral trajectories and gravitational waveforms

The inspiral of a ``small'' ($\mu \sim 1-100 M_\odot$) compact body into a ``large'' ($M \sim 10^{5-7} M_\odot$) black hole is a key source of gravitational radiation for the space-based gravitational-wave observatory LISA. The waves from such inspirals will probe the extreme strong-field nature of the Kerr metric. In this paper, I investigate the properties of a restricted family of such inspirals (the inspiral of circular, inclined orbits) with an eye toward understanding observable properties of the gravitational waves that they generate. Using results previously presented to calculate the effects of radiation reaction, I assemble the inspiral trajectories (assuming that radiation reacts adiabatically, so that over short timescales the trajectory is approximately geodesic) and calculate the wave generated as the compact body spirals in. I do this analysis for several black hole spins, sampling a range that should be indicative of what spins we will encounter in nature. The spin has a very strong impact on the waveform. In particular, when the hole rotates very rapidly, tidal coupling between the inspiraling body and the event horizon has a very strong influence on the inspiral time scale, which in turn has a big impact on the gravitational wave phasing. The gravitational waves themselves are very usefully described as ``multi-voice chirps'': the wave is a sum of ``voices'', each corresponding to a different harmonic of the fundamental orbital frequencies. Each voice has a rather simple phase evolution. Searching for extreme mass ratio inspirals voice-by-voice may be more effective than searching for the summed waveform all at once.Comment: 15 pages, 11 figures, accepted for publication in PRD. This version incorporates referee's comments, and is much less verbos

Phenomenology of the Gowdy Universe on T3×RT^3 \times R

Numerical studies of the plane symmetric, vacuum Gowdy universe on $T^3 \times R$ yield strong support for the conjectured asymptotically velocity term dominated (AVTD) behavior of its evolution toward the singularity except, perhaps, at isolated spatial points. A generic solution is characterized by spiky features and apparent ``discontinuities'' in the wave amplitudes. It is shown that the nonlinear terms in the wave equations drive the system generically to the ``small velocity'' AVTD regime and that the spiky features are caused by the absence of these terms at isolated spatial points.Comment: 19 pages, 21 figures, uses Revtex, psfi

Comparing Formulations of Generalized Quantum Mechanics for Reparametrization-Invariant Systems

A class of decoherence schemes is described for implementing the principles of generalized quantum theory in reparametrization-invariant `hyperbolic' models such as minisuperspace quantum cosmology. The connection with sum-over-histories constructions is exhibited and the physical equivalence or inequivalence of different such schemes is analyzed. The discussion focuses on comparing constructions based on the Klein-Gordon product with those based on the induced (a.k.a. Rieffel, Refined Algebraic, Group Averaging, or Spectral Analysis) inner product. It is shown that the Klein-Gordon and induced products can be simply related for the models of interest. This fact is then used to establish isomorphisms between certain decoherence schemes based on these products.Comment: 21 pages ReVTe

Identifying Critical Roles for the Lamin B Receptor and Additional Nuclear Envelope Proteins in Regulating the Proliferation and Differentiation of Myeloid Progenitors

Neutrophils are blood phagocytes that contain lobulated nuclei, development of which depend on the expression of an inner nuclear membrane (INM) protein called the lamin B receptor (LBR). Loss of LBR expression causes not only hypolobulation of neutrophil nuclei (Pelger-Huët anomaly) but also severe developmental defects in humans (HEM/Greenberg dysplasia) and mice (ichthyosis). LBR is considered a dual function protein: the N-terminal domain contains chromatin and lamin B binding sites, whereas the C-terminal domain anchors LBR to the INM and exhibits C14 sterol reductase activity. Despite our knowledge of these two structural features of LBR, which domain supports normal development is unclear. We recently addressed this issue with regards to myelopoiesis by expressing wild-type and mutant forms of mouse Lbr in myeloid cells derived from an ichthyosis mouse. We demonstrated that expression of the Lbr sterol reductase domain alone can support nuclear morphologic maturation and is critical to both cholesterol biosynthesis and lipid-stressed proliferative responses of myeloid progenitors. In contrast, myeloid progenitors that lack the homologous C14 sterol reductase Tm7sf2 displayed normal nuclear maturation, cholesterol biosynthesis and lipid-stressed proliferation. We have now generated ichthyosis myeloid cells that express forms of Lbr with missense mutations in the sterol reductase domain known to cause HEM/Greenberg dysplasia. Our preliminary results indicate that these sterol reductase missense mutations disrupt cholesterol biosynthesis and lipid-stressed proliferation, but do not appear to affect nuclear maturation. We are also analyzing the expression patterns of Lbr and two additional nuclear envelope (NE) proteins, Lamin A/C and Sun2, during neutrophil vs. macrophage differentiation using both cell line models and ex vivo differentiated mouse bone marrow, and examining how overexpression of either Lamin A/C or Sun2 affects myeloid differentiation. Our studies may reveal new insight into how different NE proteins regulate the complex functions of two professional phagocytes

Exact Hypersurface-Homogeneous Solutions in Cosmology and Astrophysics

A framework is introduced which explains the existence and similarities of most exact solutions of the Einstein equations with a wide range of sources for the class of hypersurface-homogeneous spacetimes which admit a Hamiltonian formulation. This class includes the spatially homogeneous cosmological models and the astrophysically interesting static spherically symmetric models as well as the stationary cylindrically symmetric models. The framework involves methods for finding and exploiting hidden symmetries and invariant submanifolds of the Hamiltonian formulation of the field equations. It unifies, simplifies and extends most known work on hypersurface-homogeneous exact solutions. It is shown that the same framework is also relevant to gravitational theories with a similar structure, like Brans-Dicke or higher-dimensional theories.Comment: 41 pages, REVTEX/LaTeX 2.09 file (don't use LaTeX2e !!!) Accepted for publication in Phys. Rev.

On the connection between the intergalactic medium and galaxies: the H I–galaxy cross-correlation at z ≲ 1

We present a new optical spectroscopic survey of 1777 ‘star-forming’ (‘SF’) and 366 ‘non-star-forming’ (‘non-SF’) galaxies at redshifts z ∼ 0-1 (2143 in total), 22 AGN and 423 stars, observed by instruments such as the Deep Imaging Multi-Object Spectrograph, the Visible Multi-Object Spectrograph and the Gemini Multi-Object Spectrograph, in three fields containing five quasi-stellar objects (QSOs) with Hubble Space Telescope (HST) ultraviolet spectroscopy. We also present a new spectroscopic survey of 173 ‘strong’ (1014 ≤ NHI≲ 1017 cm−2) and 496 ‘weak’ (1013 ≲ NHI 50 per cent of ‘weak’ H i systems reside within galaxy voids (hence not correlated with galaxies), and are confined in dark matter haloes of masses smaller than those hosting ‘strong’ systems and/or galaxies. We speculate that H i systems within galaxy voids might still be evolving in the linear regime even at scales ≲2 Mpc