19,124 research outputs found
Locating the critical end point using the linear sigma model coupled to quarks
We use the linear sigma model coupled to quarks to compute the effective
potential beyond the mean field approximation, including the contribution of
the ring diagrams at finite temperature and baryon density. We determine the
model couplings and use them to study the phase diagram in the baryon chemical
potential-temperature plane and to locate the Critical End Point.Comment: 8 pages, 2 figures, conference paper from ISMD 201
Isocausal spacetimes may have different causal boundaries
We construct an example which shows that two isocausal spacetimes, in the
sense introduced by Garc\'ia-Parrado and Senovilla, may have c-boundaries which
are not equal (more precisely, not equivalent, as no bijection between the
completions can preserve all the binary relations induced by causality). This
example also suggests that isocausality can be useful for the understanding and
computation of the c-boundary.Comment: Minor modifications, including the title, which matches now with the
published version. 12 pages, 3 figure
The role of fiscal rules and institutions in shaping budgetary outcomes
The Workshop "The role of fiscal rules and institutions in shaping budgetary outcomes" organized by the Directorate-General for Economic and Financial affairs of the European Commission on 24 November 2006 in Brussels aimed at enriching the debate on the fiscal arrangements and improving the understanding of their functioning. This Economic Paper contains all the paper presented in this event that was organised in four sessions. A first set of papers mainly focus on the impact of numerical fiscal rules on budgetary outturns. Other paper deal primarily with the appropriate design of fiscal rules and institutions. An additional group of papers addresses the relationship between the fiscal governance approach adopted by the EU Member States and their institutional and political frameworks. Finally the remaining presentations relate more directly to policy experiences.ĂÂ fiscal rules, budget, institutions.fiscal rules, budget, institutions, Ayuso-i-Casals, Deroose, Flores, Moulin
Unsupervised classification and areal measurement of land and water coastal features on the Texas coast
Multispectral scanner (MSS) digital data from ERTS-1 was used to delineate coastal land, vegetative, and water features in two portions of the Texas Coastal Zone. Data (Scene ID's 1037-16244 and 1037-16251) acquired on August 29, 1972, were analyzed on NASA Johnson Space Center systems through the use of two clustering algorithms. Seventeen to 30 spectrally homogeneous classes were so defined. Many classes were identified as being pure features such as water masses, salt marsh, beaches, pine, hardwoods, and exposed soil or construction materials. Most classes were identified to be mixtures of the pure class types. Using an objective technique for measuring the percentage of wetland along salt marsh boundaries, an analysis was made of the accuracy of areal measurement of salt marshes. Accuracies ranged from 89 to 99 percent. Aircraft photography was used as the basis for determining the true areal size of salt marshes in the study sites
Kinematic study of planetary nebulae in NGC 6822
By measuring precise radial velocities of planetary nebulae (which belong to
the intermediate age population), H II regions, and A-type supergiant stars
(which are members of the young population) in NGC 6822, we aim to determine if
both types of population share the kinematics of the disk of H I found in this
galaxy.
Spectroscopic data for four planetary nebulae were obtained with the high
spectral resolution spectrograph Magellan Inamori Kyocera Echelle (MIKE) on the
Magellan telescope at Las Campanas Observatory. Data for other three PNe and
one H II region were obtained from the SPM Catalog of Extragalactic Planetary
Nebulae which employed the Manchester Echelle Spectrometer attached to the 2.1m
telescope at the Observatorio Astron\'omico Nacional, M\'exico. In the
wavelength calibrated spectra, the heliocentric radial velocities were measured
with a precision better than 5-6 km s. Data for three additional H II
regions and a couple of A-type supergiant stars were collected from the
literature. The heliocentric radial velocities of the different objects were
compared to the velocities of the H i disk at the same position.
From the analysis of radial velocities it is found that H II regions and
A-type supergiants do share the kinematics of the H I disk at the same
position, as expected for these young objects. On the contrary, planetary
nebula velocities differ significantly from that of the H I at the same
position. The kinematics of planetary nebulae is independent from the young
population kinematics and it is closer to the behavior shown by carbon stars,
which are intermediate-age members of the stellar spheroid existing in this
galaxy. Our results are confirming that there are at least two very different
kinematical systems in NGC 6822
The distribution of oxygen at the Ni81Fe19/Ta interface
The knowledge of how oxygen atoms are distributed at a magnetic-metal /
oxide, or magnetic-metal / non-magnetic-metal interface, can be an useful tool
to optimize device production. Multilayered Ni81Fe19 / Ta samples consisting of
15 bilayers of 2.5 nm each, grown onto glass substrates by magnetron sputtering
from Ni81Fe19 and Ta targets, have been investigated. X-ray absorption near
edge structure, extended X-Ray absorption fine structure, small angle X-ray
diffraction, and simulations, were used to characterize the samples. Oxygen
atoms incorporated onto Ni81Fe19 films during O2 exposition are mainly bonded
to Fe atoms. This partial oxidation of the Ni81Fe19 surface works as a barrier
to arriving Ta atoms, preventing intermixing at the Ni81Fe19 / Ta interface.
The reduction of the Ni81Fe19 surface by the formation of TaO x is observed.Comment: 14 pages, 9 figures, accepted for publication in Advances in
Materials Science and Engineerin
Estancia corta : una oportunidad para identificar, desarrollar y evaluar el nivel de desarrollo de algunas competencias en alumnos de IngenierĂa QuĂmica
En este trabajo con carĂĄcter exploratorio, se presenta la identificaciĂłn de algunas competencias desarrolladas que manifiestan estudiantes de la carrera de IngenierĂa QuĂmica I. Q. ) en la soluciĂłn de un problema nuevo sobre agua contaminada durante una Estancia Corta en el Laboratorio de IngenierĂa QuĂmica. No se pretende generalizar las competencias identificadas para la carrera de IQ de esta Facultad sino el abrir un espacio participativo (acadĂ©micos, industriales, exalumnos) para la reflexiĂłn y mejora del proceso de enseñaza â aprendizaje de la I Q. Ante la incertidumbre provocada por los cambios globales y las demandas sobre calidad, eficiencia y eficacia de la educaciĂłn provocan que de manera permanente el sector Educativo, rediseñan los planes de estudio, reorientan los modelos educativos y redefinan el perfil de egreso
Computational aspects of zonal algorithms for solving the compressible Navier-Stokes equations in three dimensions
Transonic flow fields about wing geometries are computed using an Euler/Navier-Stokes approach in which the flow field is divided into several zones. The flow field immediately adjacent to the wing surface is resolved with fine grid zones and solved using a Navier-Stokes algorithm. Flow field regions removed from the wing are resolved with less finely clustered grid zones and are solved with an Euler algorithm. Computational issues associated with this zonal approach, including data base management aspects, are discussed. Solutions are obtained that are in good agreement with experiment, including cases with significant wind tunnel wall effects. Additional cases with significant shock induced separation on the upper wing surface are also presented
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