9,153 research outputs found
Finite-Temperature Gluon Condensate with Renormalization Group Flow Equations
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
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
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
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
On the conceptual nature of hybrid adverbials in Isu
We review Kießling’s (2011) assessment of the emergence of hybrid adverbials from serial verb constructions in Isu of Bantoid and the Narrow Grassfield group of East Benue Congo. He posits two paths, preverbal and postverbal, that coverb elements follow as they abandon verbal properties pertaining to syntax, morphology, and tone. Our focus rests on whether this impressive array of grammatical change might reflect a particular system of semantic concepts. We contend that one lens through which to view such a system consists of a merger of Dixon’s secondary concept types and Nuyts’ hierarchy of categories conveying clausal modification. To support our contention, we apply the resulting system of semantic concepts to Isu preverbal hybrid adverbials, finding eight conceptual types oriented toward characterization of grammatical subject. Despite the highly tentative nature of this effort, results align with a similar range of conceptual types that occur as preverbs in West Benue Congo Yoruboid and Edoid, which have also grammaticalized from verbs
Vertical laser beam propagation through the troposphere
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
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
Mapping the phase diagram of strongly interacting matter
We employ a conformal mapping to explore the thermodynamics of strongly
interacting matter at finite values of the baryon chemical potential .
This method allows us to identify the singularity corresponding to the critical
point of a second-order phase transition at finite , given information
only at . 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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