28,762 research outputs found
Introduction: forest growth and forest ecosystem carbon budgets in relation to climate change.
PACS and SPIRE photometer maps of Mâ33: First results of the HERschelâMâ33 Extended Survey (HERM33ES)
Context. Within the framework of the HERM33ES key program, we are studying the star forming interstellar medium in the nearby, metal-poor spiral galaxy Mâ33, exploiting the high resolution and sensitivity of Herschel.
Aims. We use PACS and SPIRE maps at 100, 160, 250, 350, and 500 ÎŒm wavelength, to study the variation of the spectral energy distributions (SEDs) with galacto-centric distance.
Methods. Detailed SED modeling is performed using azimuthally averaged fluxes in elliptical rings of 2 kpc width, out to 8 kpc galacto-centric distance. Simple isothermal and two-component grey body models, with fixed dust emissivity index, are fitted to the SEDs between 24 ÎŒm and 500 ÎŒm using also MIPS/Spitzerâ data, to derive first estimates of the dust physical conditions.
Results. The far-infrared and submillimeter maps reveal the branched, knotted spiral structure of Mâ33. An underlying diffuse disk is seen in all SPIRE maps (250â500 ÎŒm). Two component fits to the SEDs agree better than isothermal models with the observed, total and radially averaged flux densities. The two component model, with ÎČ fixed at 1.5, best fits the global and the radial SEDs. The cold dust component clearly dominates; the relative mass of the warm component is less than 0.3% for all the fits. The temperature of the warm component is not well constrained and is found to be about 60 K ± 10 K. The temperature of the cold component drops significantly from ~24 K in the inner 2 kpc radius to 13 K beyond 6 kpc radial distance, for the best fitting model. The gas-to-dust ratio for ÎČ = 1.5, averaged over the galaxy, is higher than the solar value by a factor of 1.5 and is roughly in agreement with the subsolar metallicity of Mâ33
GRAPHICAL CONFIGURATION PROGRAMMING - THE STRUCTURAL DESCRIPTION, CONSTRUCTION AND EVOLUTION OF SOFTWARE SYSTEMS USING GRAPHICS
Published versio
A Twisting Electrovac Solution of Type II with the Cosmological Constant
An exact solution of the current-free Einstein-Maxwell equations with the
cosmological constant is presented. It is of Petrov type II, and its double
principal null vector is geodesic, shear-free, expanding, and twisting. The
solution contains five constants. Its electromagnetic field is non-null and
aligned. The solution admits only one Killing vector and includes, as special
cases, several known solutions.Comment: 4 pages, LaTeX 2e, no figures. The present (second) version,
identical to that published in General Relativity and Gravitation, is derived
from the first version by presenting the admitted Killing vector, and by
adding the last paragraph, two footnotes (here Footnotes 1 and 3), and two
references (here Refs. [3,4]
Managing Medicaid Pharmacy Benefits: Current Issues and Options
Examines issues and considerations for state reforms of Medicaid prescription drug reimbursement, pharmacy management, and cost sharing and other best practices for realizing savings
Equilibrium and non-equilibrium concepts in forest genetic modelling: population- and individually-based approaches
The environment is changing and so are forests, in their functioning, in species composition, and in the speciesâ genetic composition. Many empirical and process-based models exist to support forest management. However, most of these models do not consider the impact of environmental changes and forest management on genetic diversity nor on the rate of adaptation of critical plant processes. How genetic diversity and rates of adaptation depend on management actions is a crucial next step in model development. Modelling approaches of genetic and demographic processes that operate in forests are categorized here in two classes. One approach assumes equilibrium conditions in phenotype and tree density, and analyses the characteristics of the demography and the genetic system of the species that determine the rate at which that equilibrium is attained. The other modelling approach does not assume equilibrium conditions and describes both the ecological âand genetic processes to analyse how environmental changes result in selection pressures on functional traits of trees and the consequences of that selection for treeâ and ecosystem functioning. The equilibrium approach allows analysing the recovery rate after a perturbation in stable environments, i.e. towards the same pre-perturbation stable state. The nonequilibrium approach allows, in addition to the equilibrium approach, analysing consequences of ongoing environmental changes and forest management, i.e. non-stationary environments, on tree functioning, species composition, and genetic composition of the trees in forest ecosystem. In this paper we describe these two modelling approaches and discuss advantages and disadvantages of them and current knowledge gaps
Sudden approximation applied to rotational excitation of molecules by atoms. ii- scat- tering of polar diatomics
Sudden approximation applied to computation of rotational transition probability and inelastic total cross sections for scattering of polar and nonpolar diatomic molecules by atom
Curvature dependent lower bounds for the first eigenvalue of the Dirac operator
Using Weitzenb\"ock techniques on any compact Riemannian spin manifold we
derive inequalities that involve a real parameter and join the eigenvalues of
the Dirac operator with curvature terms. The discussion of these inequalities
yields vanishing theorems for the kernel of the Dirac operator and lower
bounds for the spectrum of if the curvature satisfies certain conditions.Comment: Latex2e, 14p
Multibranch Bogoliubov-Bloch spectrum of a cigar shaped Bose condensate in an optical lattice
We study properties of excited states of an array of weakly coupled
quasi-two-dimensional Bose condensates by using the hydrodynamic theory. The
spectrum of the axial excited states strongly depends on the coupling among the
various discrete radial modes in a given symmetry. By including mode-coupling
within a given symmetry, the complete excitation spectrum of axial
quasiparticles with various discrete radial nodes are presented. A single
parameter which determines the strength of the mode coupling is identified. The
excitation spectrum in the zero angular momentum sector can be observed by
using the Bragg scattering experiments.Comment: to apper in Phys. Rev.
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