Signature of chaos in gravitational waves from a spinning particle

A spinning test particle around a Schwarzschild black hole shows a chaotic behavior, if its spin is larger than a critical value. We discuss whether or not some peculiar signature of chaos appears in the gravitational waves emitted from such a system. Calculating the emitted gravitational waves by use of the quadrupole formula, we find that the energy emission rate of gravitational waves for a chaotic orbit is about 10 times larger than that for a circular orbit, but the same enhancement is also obtained by a regular "elliptic" orbit. A chaotic motion is not always enhance the energy emission rate maximally. As for the energy spectra of the gravitational waves, we find some characteristic feature for a chaotic orbit. It may tell us how to find out a chaotic behavior of the system. Such a peculiar behavior, if it will be found, may also provide us some additional informations to determine parameters of a system such as a spin.Comment: 14 pages, LaTeX, to appear in Phys. Rev.

Nonlinear time-series analysis of Hyperion's lightcurves

Hyperion is a satellite of Saturn that was predicted to remain in a chaotic rotational state. This was confirmed to some extent by Voyager 2 and Cassini series of images and some ground-based photometric observations. The aim of this aticle is to explore conditions for potential observations to meet in order to estimate a maximal Lyapunov Exponent (mLE), which being positive is an indicator of chaos and allows to characterise it quantitatively. Lightcurves existing in literature as well as numerical simulations are examined using standard tools of theory of chaos. It is found that existing datasets are too short and undersampled to detect a positive mLE, although its presence is not rejected. Analysis of simulated lightcurves leads to an assertion that observations from one site should be performed over a year-long period to detect a positive mLE, if present, in a reliable way. Another approach would be to use 2---3 telescopes spread over the world to have observations distributed more uniformly. This may be achieved without disrupting other observational projects being conducted. The necessity of time-series to be stationary is highly stressed.Comment: 34 pages, 12 figures, 4 tables; v2 after referee report; matches the version accepted in Astrophysics and Space Scienc

Alphacoronaviruses in New World Bats: Prevalence, Persistence, Phylogeny, and Potential for Interaction with Humans

Bats are reservoirs for many different coronaviruses (CoVs) as well as many other important zoonotic viruses. We sampled feces and/or anal swabs of 1,044 insectivorous bats of 2 families and 17 species from 21 different locations within Colorado from 2007 to 2009. We detected alphacoronavirus RNA in bats of 4 species: big brown bats (Eptesicus fuscus), 10% prevalence; long-legged bats (Myotis volans), 8% prevalence; little brown bats (Myotis lucifugus), 3% prevalence; and western long-eared bats (Myotis evotis), 2% prevalence. Overall, juvenile bats were twice as likely to be positive for CoV RNA as adult bats. At two of the rural sampling sites, CoV RNAs were detected in big brown and long-legged bats during the three sequential summers of this study. CoV RNA was detected in big brown bats in all five of the urban maternity roosts sampled throughout each of the periods tested. Individually tagged big brown bats that were positive for CoV RNA and later sampled again all became CoV RNA negative. Nucleotide sequences in the RdRp gene fell into 3 main clusters, all distinct from those of Old World bats. Similar nucleotide sequences were found in amplicons from gene 1b and the spike gene in both a big-brown and a long-legged bat, indicating that a CoV may be capable of infecting bats of different genera. These data suggest that ongoing evolution of CoVs in bats creates the possibility of a continued threat for emergence into hosts of other species. Alphacoronavirus RNA was detected at a high prevalence in big brown bats in roosts in close proximity to human habitations (10%) and known to have direct contact with people (19%), suggesting that significant potential opportunities exist for cross-species transmission of these viruses. Further CoV surveillance studies in bats throughout the Americas are warranted

Photometry of Phoebe

Observatios of Phoebe (S9) in the V filter at small solar phase angles (0.2° to 1.2°) with the MIT SNAPSHOT CCD are presented. The value of Phoebe\u27s sideral rotational period is refined to 9.282 ± 0.015hr. Assuming the Voyager-derived 110 km radius, Phoebe\u27s observed mean opposition V magnitude of 16.176 ± 0.033 (extrapolated from small angles) corresponds to a geometric albedo of 0.084 ± 0.003. A strong opposition effect is indicated by the 0.180 ± 0.035 mag/deg solar phase coefficient observed at these small phase angles. The data are shown to be compatible with a phase function for C-type asteroids (K. Lumme and E. Bowell, 1981, Astron. J. 86, 1705–1721; K. Lumme, E. Bowell, and A. W. Harris, 1984, Bull. Amer. Astron. Soc. 16, 684), but give a poorer fit to the average asteroid phase relation of T. Gehrels and E.F. Tedesco (1979, Astron. J. 84, 1079–1087). Phoebe\u27s rotational lightcurve in the V filter is roughly sinusoidal, with a 0.230-mag peak-to-peak amplitude and weaker higher order harmonics indicating primarily bimodal surface feature contrast. In addition to these photometric results, precise positions on 3 nights are given

Comparison Of Mass Fluxes Predicted By The Dusty-gas And A Modified Dusty-gas Model

The equations of the dusty-gas model (homoporous model) are modified through the use of correction factors which account for the effects the pore-size and tortuosity distributions have on the mass fluxes in heteroporous media. When the correction factors approach unity, the modified dusty-gas model approaches the behavior of the dusty-gas equations; this occurs when the pressure of the system is either very low or very high because, at either extreme, almost all pores in a porous medium are in a single transport regime, that is either Knudsen or molecular diffusion. A comparison of the mass fluxes predicted by the modified dusty-gas (heteroporous model) and the dusty-gas models for binary isobaric diffusion and simultaneous flow and diffusion, shows that the percentage deviation between NiMDG and NiDG. (i species A or B) may be, in some cases, significant (up to 75% for the porous media studied in this work); this indicates that the dusty-gas model (homoporous model) could fail in predicting accurately the mass fluxes in porous media with wide pore-size distributions. The percentage deviation in the mass fluxes becomes smaller as the pressure increases above certain values at which the deviation of the correction factors from unity is small. © 1982

Formation and characterization of highly-dispersed metal colloid catalysts

The objective of this research is to explore the feasibility of using small metal colloids, in microemulsions, as catalysts. The product of this work will be a new concept for tailoring highly dispersed materials to specific catalytic reactions. The knowledge gained from the proposed research will be broadly applicable to variety of reactions, including hydrogenation, synthesis gas conversion, and hydrogen conversion. To achieve this objective, a plan has been formulated to prepare and characterize catalyst particles in organic solvents and to explore the use of catalyst particles. In this paper, we will discuss the use of inverse micelles to solubilize significant quantities of metal compounds in hydrocarbon solvents and their reduction, decomposition, and sulfidation to give colloidal catalytic materials. We will also discuss in detail the characterization of these materials, present preliminary results for the catalytic hydropyrolysis of coals, and discuss the results of our evaluation of selected metal colloids in catalytic hydrogenation of pyrene. 9 refs., 3 tabs

Chemical Reactions With Mole Changes In Heteroporous Catalysts—Part II

In this short communication, the modified dusty-gas model1-3is used to describe the mass fluxes and to estimate the effectiveness factors in the transition regime of second order irreversible reactions with mole changes in heteroporous media. The results of this note show that the effectiveness factors predicted by the dusty-gas model are larger (up to about 30% for the systems examined) than those estimated by the modified dusty-gas model which accounts for the effects the pore-size and tortuosity distributions have on the mass fluxes in industrial heteroporous catalysts. © 1984, Taylor & Francis Group, LLC. All rights reserved