7,332 research outputs found
Airphoto use in resource management - A survey of non-federal purchasers of agricultural stabilization and conservation service airphotos
Survey and analysis of nonfederal users of spacecraft aerial photographs sold by US Department of Agricultur
Note on Anomalous Higgs-Boson Couplings in Effective Field Theory
We propose a parametrization of anomalous Higgs-boson couplings that is both
systematic and practical. It is based on the electroweak chiral Lagrangian,
including a light Higgs boson, as the effective field theory (EFT) at the
electroweak scale . This is the appropriate framework for the case of
sizeable deviations in the Higgs couplings of order from the Standard
Model, considered to be parametrically larger than new-physics effects in the
sector of electroweak gauge interactions. The role of power counting in
identifying the relevant parameters is emphasized. The three relevant scales,
, the scale of new Higgs dynamics , and the cut-off ,
admit expansions in and . The former corresponds
to an organization of operators by their canonical dimension, the latter by
their loop order or chiral dimension. In full generality the EFT is thus
organized as a double expansion. However, as long as the EFT
systematics is closer to the chiral counting. The leading effects in the
consistent approximation provided by the EFT, relevant for the presently most
important processes of Higgs production and decay, are given by a few
(typically six) couplings. These parameters allow us to describe the properties
of the Higgs boson in a general and systematic way, and with a precision
adequate for the measurements to be performed at the LHC. The framework can be
systematically extended to include loop corrections and higher-order terms in
the EFT.Comment: 7 pages, no figures; typos corrected; references adde
On the Detectability of Oxygen X-ray Fluorescence and its Use as a Solar Photospheric Abundance Diagnostic
Monte Carlo calculations of the O Kalpha line fluoresced by coronal X-rays
and emitted just above the temperature minimum region of the solar atmosphere
have been employed to investigate the use of this feature as an abundance
diagnostic. While quite weak, we estimate line equivalent widths in the range
0.02-0.2 AA, depending on the X-ray plasma temperature. The line remains
essentially uncontaminated by blends for coronal temperatures T =< 3e6 K and
should be quite observable, with a flux >~ 2 ph/s/arcmin^2. Model calculations
for solar chemical mixtures with an O abundance adjusted up and down by a
factor of 2 indicate 35-60% changes in O Kalpha line equivalent width,
providing a potentially useful O abundance diagnostic. Sensitivity of
equivalent width to differences between recently recommended chemical
compositions with ``high'' and ``low'' complements of the CNO trio important
for interpreting helioseismological observations is less accute, amounting to
20-26% at coronal temperatures T ~< 2e6 K. While still feasible for
discriminating between these two mixtures, uncertainties in measured line
equivalent widths and in the models used for interpretation would need to be
significantly less than 20%. Provided a sensitive X-ray spectrometer with
resolving power >= 1000 and suitably well-behaved instrumental profile can be
built, X-ray fluorescence presents a viable means for resolving the solar
``oxygen crisis''.Comment: To appear in the Astrophysical Journa
Complete One-Loop Renormalization of the Higgs-Electroweak Chiral Lagrangian
Employing background-field method and super-heat-kernel expansion, we compute
the complete one-loop renormalization of the electroweak chiral Lagrangian with
a light Higgs boson. Earlier results from purely scalar fluctuations are
confirmed as a special case. We also recover the one-loop renormalization of
the conventional Standard Model in the appropriate limit.Comment: 15 pages, no figures; v2: reference and comments added, typos fixed,
matches published versio
Automatic construction of boundary parametrizations for geometric multigrid solvers
We present an algorithm that constructs parametrizations of boundary and interface surfaces automatically. Starting with high-resolution triangulated surfaces describing the computational domains, we iteratively simplify the surfaces yielding a coarse approximation of the boundaries with the same topological type. While simplifying we construct a function that is defined on the coarse surface and whose image is the original surface. This function allows access to the correct shape and surface normals of the original surface as well as to any kind of data defined on it. Such information can be used by geometric multigrid solvers doing adaptive mesh refinement. Our algorithm runs stable on all types of input surfaces, including those that describe domains consisting of several materials. We have used our method with success in different fields and we discuss examples from structural mechanics and biomechanics
Absorptive part of meson--baryon scattering amplitude and baryon polarization in chiral perturbation theory
We compute the spin asymmetry and polarization of the final-state baryon in
its rest frame in two-body meson--baryon low-energy scattering with unpolarized
initial state, to lowest non-trivial order in BChPT. The required absorptive
amplitudes are obtained analytically at one-loop level. We discuss the
polarization results numerically for several meson--baryon processes. Even at
low energies above threshold, where BChPT can reasonably be expected to be
applicable, sizable values of polarization are found for some processes
Using the object modeling system for hydrological model development and application
State of the art challenges in sustainable management of water resources have created demand for integrated, flexible and easy to use hydrological models which are able to simulate the quantitative and qualitative aspects of the hydrological cycle with a sufficient degree of certainty. Existing models which have been de-veloped to fit these needs are often constrained to specific scales or purposes and thus can not be easily adapted to meet different challenges. As a solution for flexible and modularised model development and application, the Object Modeling System (OMS) has been developed in a joint approach by the USDA-ARS, GPSRU (Fort Collins, CO, USA), USGS (Denver, CO, USA), and the FSU (Jena, Germany). The OMS provides a modern modelling framework which allows the implementation of single process components to be compiled and applied as custom tailored model assemblies. This paper describes basic principles of the OMS and its main components and explains in more detail how the problems during coupling of models or model components are solved inside the system. It highlights the integration of different spatial and temporal scales by their representation as spatial modelling entities embedded into time compound components. As an exam-ple the implementation of the hydrological model J2000 is discussed
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