8,937 research outputs found

    Finite-Temperature Gluon Condensate with Renormalization Group Flow Equations

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    Within a self-consistent proper-time Renormalization Group (RG) approach we investigate an effective QCD trace anomaly realization with dilatons and determine the finite-temperature behavior of the gluon condensate. Fixing the effective model at vanishing temperature to the glueball mass and the bag constant a possible gluonic phase transition is explored in detail. Within the RG framework the full non-truncated dilaton potential analysis is compared with a truncated potential version.Comment: 22 pages, 11 figures, LaTeX2e; revised version accepted for publication in Phys. Rev.

    Annotated Checklist of the Pentatomidae (Heteroptera) of Connecticut

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    We provide town data for the Pentatomidae in Connecticut. Although this state has been much collected, most sampling has been limited to only a few lo- cations. Species newly recorded for Connecticut are: Halyomorpha halys (Stål), Hymenarcys nervosa (Say), Banasa euchlora Stål, B. sordida (Uhler), and Perillus bioculatus (Fabricius). Podisus neglectus (Westwood) may occur in the state. Other species found in neighboring states may eventually be found in Connecticut: Picromerus bidens (Linnaeus), Rhacognathus americanus Stål, Mcphersonarcys aequalis (Say), Thyanta custator custator (Fabricius), T. custator acerra McAtee, and Amaurochrous brevitylus (Barber and Sailer). We briefly analyze these data, recognizing some faunal elements. More collecting needs to be conducted in the state, so that distribution patterns outlined here can be more broadly understood, and so that species of potential conservation concern can be identified

    Remote systems development

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    Potential space missions of the nineties and the next century require that we look at the broad category of remote systems as an important means to achieve cost-effective operations, exploration and colonization objectives. This paper addresses such missions, which can use remote systems technology as the basis for identifying required capabilities which must be provided. The relationship of the space-based tasks to similar tasks required for terrestrial applications is discussed. The development status of the required technology is assessed and major issues which must be addressed to meet future requirements are identified. This includes the proper mix of humans and machines, from pure teleoperation to full autonomy; the degree of worksite compatibility for a robotic system; and the required design parameters, such as degrees-of-freedom. Methods for resolution are discussed including analysis, graphical simulation and the use of laboratory test beds. Grumman experience in the application of these techniques to a variety of design issues are presented utilizing the Telerobotics Development Laboratory which includes a 17-DOF robot system, a variety of sensing elements, Deneb/IRIS graphics workstations and control stations. The use of task/worksite mockups, remote system development test beds and graphical analysis are discussed with examples of typical results such as estimates of task times, task feasibility and resulting recommendations for design changes. The relationship of this experience and lessons-learned to future development of remote systems is also discussed

    Properties and use of CMB power spectrum likelihoods

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    Fast robust methods for calculating likelihoods from CMB observations on small scales generally rely on approximations based on a set of power spectrum estimators and their covariances. We investigate the optimality of these approximation, how accurate the covariance needs to be, and how to estimate the covariance from simulations. For a simple case with azimuthal symmetry we compare optimality of hybrid pseudo-C_l CMB power spectrum estimators with the exact result, indicating that the loss of information is not negligible, but neither is it enough to have a large effect on standard parameter constraints. We then discuss the number of samples required to estimate the covariance from simulations, with and without a good analytic approximation, and assess the use of shrinkage estimators. Finally we discuss how to combine an approximate high-ell likelihood with a more exact low-ell harmonic-space likelihood as a practical method for accurate likelihood calculation on all scales.Comment: 15 pages, 11 figures; updated to match version accepted by PR

    Vertical laser beam propagation through the troposphere

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    The characteristics of the earth's atmosphere and its effects upon laser beams was investigated in a series of balloon borne, optical propagation experiments. These experiments were designed to simulate the space to ground laser link. An experiment to determine the amplitude fluctuation, commonly called scintillation, caused by the atmosphere was described

    Exceptional Points in a Microwave Billiard with Time-Reversal Invariance Violation

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    We report on the experimental study of an exceptional point (EP) in a dissipative microwave billiard with induced time-reversal invariance (T) violation. The associated two-state Hamiltonian is non-Hermitian and non-symmetric. It is determined experimentally on a narrow grid in a parameter plane around the EP. At the EP the size of T violation is given by the relative phase of the eigenvector components. The eigenvectors are adiabatically transported around the EP, whereupon they gather geometric phases and in addition geometric amplitudes different from unity

    Is secularism a world religion?

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    Mapping the phase diagram of strongly interacting matter

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    We employ a conformal mapping to explore the thermodynamics of strongly interacting matter at finite values of the baryon chemical potential μ\mu. This method allows us to identify the singularity corresponding to the critical point of a second-order phase transition at finite μ\mu, given information only at μ=0\mu=0. The scheme is potentially useful for computing thermodynamic properties of strongly interacting hot and dense matter in lattice gauge theory. The technique is illustrated by an application to a chiral effective model.Comment: 5 pages, 3 figures; published versio
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