2,783 research outputs found
Perspectiva estructuralista de la innovación : evaluación del entrenamiento en Andalucía como minoración del estrés
Este informe describe y compara percepciones desenvueltas de profesores'
con ansiedad profesional sobre actividades de formacion permanente realizadas
en Andalucía. Se contrastaron 20 hipótesis principales, curtidas en 89
subhipótesis. Los profesores no se distinguieron entre sí por variables de hondura
contextual o condición demográfica. Se confirmaron las diferencias en el
profesorado por algún factor articulador de actividades formativas: motiva
participante, saberes adquiridos, contenido de cursos, calidad de acti--ción de
vidades formativas y medida de la eficacia de cursos.__________________________________
This report describes and compares perceptions of teachers participating on
in-service training activities in Andalucia with regard to professional
anxiety. 20 main hypothesis were contrasted involving 89 subhypothesis. The
teachers don't distinguish between them for contextual depth variables or
demographic condition. The differences found among teachers were through
factor which refer to formative activities: participant motivation, acquired
knowledges, content of courses, quality of formative activities, and measurement
of the efficacy of courses
Impact of the new solar abundances on the calibration of the PMS binary system RS Cha
Context: In a recent work, we tried to obtain a calibration of the two
components of the pre-main sequence binary system RS Cha by means of
theoretical stellar models. We found that the only way to reproduce the
observational parameters of RS Cha with standard stellar models is to decrease
the initial abundances of carbon and nitrogen derived from the GN93 solar
mixture of heavy elements by a few tenths of dex.
Aims: In this work, we aim to reproduce the observational properties of the
RS Cha stars with stellar evolution models based on the new AGS05 solar mixture
recently derived from a three-dimensional solar model atmosphere. The AGS05
mixture is depleted in carbon, nitrogen and oxygen with respect to the GN93
mixture.
Methods: We calculated new stellar models of the RS Cha components using the
AGS05 mixture and appropriate opacity tables. We sought models that
simultaneously satisfy the observations of the two components (masses, radii,
luminosities, effective temperatures and metallicity).
Results: We find that it is possible to reproduce the observational data of
the RS Cha stars with AGS05 models based on standard input physics. From these
models, the initial helium content of the system is Y~0.255 and its age is
~9.13 +- 0.12 Myr.Comment: Research note accepted in A&A, 5 pages, 2 figure
Isotope analysis reveals foraging area dichotomy for Atlantic leatherback turtles
Background: The leatherback turtle (Dermachelys corlacea) has undergone a dramatic decline over the last 25 years, and this is believed to be primarily the results of mortality associated with fisheries bycatch followed by egg and nesting female harvest, Atlantic leatherback turtles undertake long migrations across ocean basins from subtropical and tropical nesting beaches to productive frontal areas; Migration between two nesting seasons can last 2 or 3 years, a time period termed the remigration interval (RI). Recent satellite transmitter data revealed that Atlantic leatherbacks follow two major dispersion patterns after nesting season, through the North Gulf Stream area or more eastward across the North Equatorial Current. However, information on the whole RI is lacking, precluding the accurate identification of feeding areas where conservation measures may need to be applied. Methodology/Principal Findings: Using stable isotopes as dietary tracers we determined the characteristics of feeding grounds of leatherback females nesting in French Guíana. During migration, 3-year RI females diffred from 2-year RI females in their isotope values, implying differences in their choice of feeding habitats (offshore vs. more coastal) and foraging latitude (North Atlantic vs. West African coasts, respectively). Egg-yolk and blood isotope values are correlated in nesting females, indicating that egg analysis is a useful tool for assessing isotope values in these turtles, including adults when not available. Conclusions/Significance: Our results complement previous data on turtle movements during the first year following the nesting season, integrating the diet consumed during the year before nesting. We suggest that the French Guiana leatherback population segregates into two distinct isotopic groupings, and highlight the urgent need to determine the feeding habitats of the turtle in the Atlantic in order to protect this species from incidental take by commercial fisheries. Our results also emphasize the use of eggs, a less-invasive sampling material than blood, to assess isotopic data and feeding habits for adult female leatherbacks
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Conductance Distributions in Random Resistor Networks: Self Averaging and Disorder Lengths
The self averaging properties of conductance are explored in random
resistor networks with a broad distribution of bond strengths
P(g)\simg^{\mu-1}. Distributions of equivalent conductances are estimated
numerically on hierarchical lattices as a function of size and distribution
tail parameter . For networks above the percolation threshold, convergence
to a Gaussian basin is always the case, except in the limit --> 0. A {\it
disorder length} is identified beyond which the system is effectively
homogeneous. This length diverges as ( is the
regular percolation correlation length exponent) as -->0. This suggest
that exactly the same critical behavior can be induced by geometrical disorder
and bu strong bond disorder with the bond occupation probability .
Only lattices at the percolation threshold have renormalized probability
distribution in a {\it Levy-like} basin. At the threshold the disorder length
diverges at a vritical tail strength as , with
, a new exponent. Critical path analysis is used in a generalized
form to give form to give the macroscopic conductance for lattice above .Comment: 16 pages plain TeX file, 6 figures available upon
request.IBC-1603-01
Forma que se ha de guardar en armar cavalleros, y dar los abitos profesiones, y colaziones de las Enmiendas a los Cavalleros de la Orden de Santiago
Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-2010Esc. xil. en port.Sign.: []4, B-F
Modeling the dynamic rupture propagation on heterogeneous faults with rate- and state-dependent friction
We investigate the effects of non-uniform distribution of constitutive parameters on the dynamic propagation of
an earthquake rupture. We use a 2D finite difference numerical method and we assume that the dynamic rupture
propagation is governed by a rate- and state-dependent constitutive law. We first discuss the results of several
numerical experiments performed with different values of the constitutive parameters a (to account for the direct
effect of friction), b (controlling the friction evolution) and L (the characteristic length-scale parameter) to
simulate the dynamic rupture propagation on homogeneous faults. Spontaneous dynamic ruptures can be simulated
on velocity weakening (a < b) fault patches: our results point out the dependence of the traction and slip velocity
evolution on the adopted constitutive parameters. We therefore model the dynamic rupture propagation on
heterogeneous faults. We use in this study the characterization of different frictional regimes proposed by
Boatwright and Cocco (1996) based on different values of the constitutive parameters a, b and L. Our numerical
simulations show that the heterogeneities of the L parameter affect the dynamic rupture propagation, control
the peak slip velocity and weakly modify the dynamic stress drop and the rupture velocity. Moreover, a barrier
can be simulated through a large contrast of L parameter. The heterogeneity of a and b parameters affects the
dynamic rupture propagation in a more complex way. A velocity strengthening area (a > b) can arrest a dynamic
rupture, but can be driven to an instability if suddenly loaded by the dynamic rupture front. Our simulations
provide a picture of the complex interactions between fault patches having different frictional properties and illustrate
how the traction and slip velocity evolutions are modified during the propagation on heterogeneous
faults. These results involve interesting implications for slip duration and fracture energy
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