1,144 research outputs found
Recommended from our members
Economic impacts on the United States of siting decisions for the international thermonuclear experimental reactor
This report presents the results of a study that examines and compares the probable short-term economic impacts of the International Thermonuclear Experimental Reactor (ITER) on the United States (U.S.) if (1) ITER were to be sited in the U.S., or (2) ITER were to be sited in one of the other countries that, along with the U.S., is currently participating in the ITER program. Life-cycle costs associated with ITER construction, operation, and decommissioning are analyzed to assess their economic impact. A number of possible U.S. host and U.S. non-host technology and cost-sharing arrangements with the other ITER Parties are examined, although cost-sharing arrangements and the process by which the Parties will select a host country and an ITER site remain open issues. Both national and local/regional economic impacts, as measured by gross domestic product, regional output, employment, net exports, and income, are considered. These impacts represent a portion of the complex, interrelated set of economic considerations that characterize U.S. host and U.S. non-host participation in ITER. A number of other potentially important economic and noneconomic considerations are discussed qualitatively
Comparing Bowen ratio-energy balance systems for measuring ET
Two Bowen ratio-energy balance (BREB) systems for measuring
evapotranspiration (ET) under wet and dry conditions were compared. The
study sites were an irrigated grass sod near Kimberly, Idaho and a sagebrush-grass
range site on the Reynolds Creek Experimental Watershed near Boise,
Idaho. One Bowen ratio system used positive-head, ceramic-wick, aspirated
psychrometers. The other system measured the vapor gradients with a cooled-mirror,
dew-point hygrometer. Differences in the amounts of ET measured by
the two systems were very small and of little practical consequence. The system
using a single-mirror, dew-point hygrometer was the most reliable, required the
least maintenance, and was the easiest to use
Avian Influenza among Waterfowl Hunters and Wildlife Professionals
We report serologic evidence of avian influenza infection in 1 duck hunter and 2 wildlife professionals with extensive histories of wild waterfowl and game bird exposure. Two laboratory methods showed evidence of past infection with influenza A/H11N9, a less common virus strain in wild ducks, in these 3 persons
Towards Solving QCD - The Transverse Zero Modes in Light-Cone Quantization
We formulate QCD in (d+1) dimensions using Dirac's front form with periodic
boundary conditions, that is, within Discretized Light-Cone Quantization. The
formalism is worked out in detail for SU(2) pure glue theory in (2+1)
dimensions which is approximated by restriction to the lowest {\it transverse}
momentum gluons. The dimensionally-reduced theory turns out to be SU(2) gauge
theory coupled to adjoint scalar matter in (1+1) dimensions. The scalar field
is the remnant of the transverse gluon. This field has modes of both non-zero
and zero {\it longitudinal} momentum. We categorize the types of zero modes
that occur into three classes, dynamical, topological, and constrained, each
well known in separate contexts. The equation for the constrained mode is
explicitly worked out. The Gauss law is rather simply resolved to extract
physical, namely color singlet states. The topological gauge mode is treated
according to two alternative scenarios related to the In the one, a spectrum is
found consistent with pure SU(2) gluons in (1+1) dimensions. In the other, the
gauge mode excitations are estimated and their role in the spectrum with
genuine Fock excitations is explored. A color singlet state is given which
satisfies Gauss' law. Its invariant mass is estimated and discussed in the
physical limit.Comment: LaTex document, 26 pages, one figure (obtainable by contacting
authors). To appear in Physical. Review
Species-specific responses of planktivorous fish to the introduction of a new piscivore: implications for prey fitness
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75539/1/j.1365-2427.2007.01810.x.pd
Relativistic Calculation of the Meson Spectrum: a Fully Covariant Treatment Versus Standard Treatments
A large number of treatments of the meson spectrum have been tried that
consider mesons as quark - anti quark bound states. Recently, we used
relativistic quantum "constraint" mechanics to introduce a fully covariant
treatment defined by two coupled Dirac equations. For field-theoretic
interactions, this procedure functions as a "quantum mechanical transform of
Bethe-Salpeter equation". Here, we test its spectral fits against those
provided by an assortment of models: Wisconsin model, Iowa State model,
Brayshaw model, and the popular semi-relativistic treatment of Godfrey and
Isgur. We find that the fit provided by the two-body Dirac model for the entire
meson spectrum competes with the best fits to partial spectra provided by the
others and does so with the smallest number of interaction functions without
additional cutoff parameters necessary to make other approaches numerically
tractable. We discuss the distinguishing features of our model that may account
for the relative overall success of its fits. Note especially that in our
approach for QCD, the resulting pion mass and associated Goldstone behavior
depend sensitively on the preservation of relativistic couplings that are
crucial for its success when solved nonperturbatively for the analogous
two-body bound-states of QED.Comment: 75 pages, 6 figures, revised content
Strand bond performance in prestressed concrete accounting for bondslip
This paper presents the results of an experimental research program addressing the bond behavior of prestressing strands in pretensioned prestressed concrete members after anchorage failure has occurred. A test methodology based on measuring the prestressing strand force and strand end slip at the specimens free end was employed. Transmission- and anchorage-length tests were performed on several series of prestressed specimens with different embedment lengths using twelve concrete mixes. Average bond stresses along the transmission length and the anchorage length were obtained for specimens with release strengths ranging from 24 MPa to 55 MPa. For the anchorage analysis, a parameter was developed that includes strand slip to be used in determining anchorage length. Based on the test results, an analysis to experimentally substantiate the Stress Waves Theory of Janney has been proposed. Additionally, the potential bond performance of prestressing strands after anchorage failure at the end regions has been suggested.The content of the present paper is based on tests which were conducted in the Institute of Concrete Science and Technology (ICITECH), at Universitat Politecnica of Valencia (Spain), in collaboration with the companies PREVALESA and ISOCRON. Funding for this experimental research work was provided by the Spanish Ministry of Education and Science/Science and Innovation and ERDF (Project BIA2006-05521 and Project BIA2009-12722). The authors wish to thank the above companies as well as the concrete structures laboratory technicians at the Universitat Politecnica of Valencia for their cooperation. Finally, the authors also wish to pay their respects to C.A. Arbelaez.Martí Vargas, JR.; Serna Ros, P.; Hale, WM. (2013). Strand bond performance in prestressed concrete accounting for bondslip. Engineering Structures. 51:236-244. doi:10.1016/j.engstruct.2013.01.023S2362445
Large-amplitude driving of a superconducting artificial atom: Interferometry, cooling, and amplitude spectroscopy
Superconducting persistent-current qubits are quantum-coherent artificial
atoms with multiple, tunable energy levels. In the presence of large-amplitude
harmonic excitation, the qubit state can be driven through one or more of the
constituent energy-level avoided crossings. The resulting
Landau-Zener-Stueckelberg (LZS) transitions mediate a rich array of
quantum-coherent phenomena. We review here three experimental works based on
LZS transitions: Mach-Zehnder-type interferometry between repeated LZS
transitions, microwave-induced cooling, and amplitude spectroscopy. These
experiments exhibit a remarkable agreement with theory, and are extensible to
other solid-state and atomic qubit modalities. We anticipate they will find
application to qubit state-preparation and control methods for quantum
information science and technology.Comment: 13 pages, 5 figure
Strongly Hyperbolic Extensions of the ADM Hamiltonian
The ADM Hamiltonian formulation of general relativity with prescribed lapse
and shift is a weakly hyperbolic system of partial differential equations. In
general weakly hyperbolic systems are not mathematically well posed. For well
posedness, the theory should be reformulated so that the complete system,
evolution equations plus gauge conditions, is (at least) strongly hyperbolic.
Traditionally, reformulation has been carried out at the level of equations of
motion. This typically destroys the variational and Hamiltonian structures of
the theory. Here I show that one can extend the ADM formalism to (i)
incorporate the gauge conditions as dynamical equations and (ii) affect the
hyperbolicity of the complete system, all while maintaining a Hamiltonian
description. The extended ADM formulation is used to obtain a strongly
hyperbolic Hamiltonian description of Einstein's theory that is generally
covariant under spatial diffeomorphisms and time reparametrizations, and has
physical characteristics. The extended Hamiltonian formulation with 1+log
slicing and gamma--driver shift conditions is weakly hyperbolic.Comment: This version contains minor corrections and clarifications. The
format has been changed to conform with IOP styl
A measurement of the tau mass and the first CPT test with tau leptons
We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV
using tau pairs from Z0 decays. To test CPT invariance we compare the masses of
the positively and negatively charged tau leptons. The relative mass difference
is found to be smaller than 3.0 10^-3 at the 90% confidence level.Comment: 10 pages, 4 figures, Submitted to Phys. Letts.
- …