311 research outputs found
Representation and usage of knowledge for initialization of accelerator control equipment
A knowledge based application, called SETUP, to initialize and diagnose the CERN/PS accelerators' control equipment is described. The object model and the general features of control algorithms are presented, together with their relation to the knowledge description of the setting up of the system. The different ways of the integration of the SETUP in the control system are outlined
Game species monitoring using road-based distance sampling in association with thermal imagers: a covariate analysis
Monitorización de especies cinegéticas utilizando el muestreo a distancia con base en una carretera, en combinación con imágenes termográficas: un análisis de covariables
La monitorización de las poblaciones de especies cinegéticas es necesaria para evaluar adecuadamente las capturas de los cazadores, en zonas que carecen de los grandes depredadores naturales. Sin embargo, los gestores de la caza deben controlar diversas especies y a menudo carecen de un método de control con un diseño conveniente. Por lo tanto, la monitorización de diversas especies al mismo tiempo en áreas muy grandes podrÃa ser eficaz desde el punto de vista de los costes y del tiempo. Estudiamos la influencia de diversos factores durante la monitorización de tres especies cinegéticas comunes (el jabalÃ, el corzo y el zorro rojo) utilizando un muestreo a distancia desde la carretera, en asociación con imágenes termográficas. Este examen piloto basado en 20 recuentos nocturnos en cinco lugares contrastantes estudió el efecto de diversas covariables (especie, termografÃa, observador, tamaño del grupo y tipo de hábitat) sobre las probabilidades de detección (dp). No se hallaron diferencias entre las imágenes termográficas (dpJENOPTIK: 0,186, dpFLIR: 0,193) y el tamaño de los grupos (dp1ind.: 0,243, dp2ind.: 0,259, dp> 2ind.: 0,223), pero sà entre los observadores (dpobs1: 0,207, dpobs2: 0,274, dpobs3: 0,159). También se observaron diferencias esperadas entre las especies (dpwild boar: 0,22, dproe deer: 0,35, dpred fox: 0,32) y entre los tipos de hábitat (dpforest: 0,27, dpedge: 0,74, dpopen: 0,35). Nuestros resultados demuestran que la detectabilidad de los equipos de termografÃa de bajo coste es similar a la de otros métodos caros, destacando nuevas posibilidades del uso de la termografÃa para los gestores de la caza. Aunque deberÃan realizarse ajustes en el diseño del estudio, nuestros hallazgos sugieren que la monitorización de múltiples especies a gran escala podrÃa ser un método eficaz para las especies cinegéticas comunes.Monitorización de especies cinegéticas utilizando el muestreo a distancia con base en una carretera, en combinación con imágenes termográficas: un análisis de covariables
La monitorización de las poblaciones de especies cinegéticas es necesaria para evaluar adecuadamente las capturas de los cazadores, en zonas que carecen de los grandes depredadores naturales. Sin embargo, los gestores de la caza deben controlar diversas especies y a menudo carecen de un método de control con un diseño conveniente. Por lo tanto, la monitorización de diversas especies al mismo tiempo en áreas muy grandes podrÃa ser eficaz desde el punto de vista de los costes y del tiempo. Estudiamos la influencia de diversos factores durante la monitorización de tres especies cinegéticas comunes (el jabalÃ, el corzo y el zorro rojo) utilizando un muestreo a distancia desde la carretera, en asociación con imágenes termográficas. Este examen piloto basado en 20 recuentos nocturnos en cinco lugares contrastantes estudió el efecto de diversas covariables (especie, termografÃa, observador, tamaño del grupo y tipo de hábitat) sobre las probabilidades de detección (dp). No se hallaron diferencias entre las imágenes termográficas (dpJENOPTIK: 0,186, dpFLIR: 0,193) y el tamaño de los grupos (dp1ind.: 0,243, dp2ind.: 0,259, dp> 2ind.: 0,223), pero sà entre los observadores (dpobs1: 0,207, dpobs2: 0,274, dpobs3: 0,159). También se observaron diferencias esperadas entre las especies (dpwild boar: 0,22, dproe deer: 0,35, dpred fox: 0,32) y entre los tipos de hábitat (dpforest: 0,27, dpedge: 0,74, dpopen: 0,35). Nuestros resultados demuestran que la detectabilidad de los equipos de termografÃa de bajo coste es similar a la de otros métodos caros, destacando nuevas posibilidades del uso de la termografÃa para los gestores de la caza. Aunque deberÃan realizarse ajustes en el diseño del estudio, nuestros hallazgos sugieren que la monitorización de múltiples especies a gran escala podrÃa ser un método eficaz para las especies cinegéticas comunes.Monitoring of game species populations is necessary to adequately assess culling by hunters in areas where natural large predators are absent. However, game managers have to control several species and they often lack of an efficient and convenient survey design method. Monitoring several species at that same time over large areas could thus be cost– and time–effective. We tested the influence of several factors during monitoring of three common game species, (wild boar, roe deer and red fox, using road–based distance sampling in association with thermal imagers. This pilot survey based on 20 night counts in five contrasting sites studied the effect of several covariates (species, thermal imaging, observer, group size, and habitat type) on the detection probabilities (= dp). No differences were observed between thermal imagers (dpJENOPTIK: 0.186, dpFLIR: 0.193) and group sizes (dp1ind.: 0.243, dp2ind.: 0.259, dp> 2ind.: 0.223), but we found differences between observers (dpobs1: 0.207, dpobs2: 0.274, dpobs3: 0.159). Expected differences were also observed between species (dpwild boar: 0.22, dproe deer: 0.35, dpred fox: 0.32) and between habitat type (dpforest: 0.27, dpedge: 0.74, dpopen: 0.35). Our results show that the detectability of low cost thermal imaging equipment is similar to that of more expensive methods, highlighting new possibilities for the use of thermal imagery by game managers. Although adjustments should be made to the study design our findings suggest that large–scale multi–species monitoring could be an efficient method for common game species
An exact analytical solution for generalized growth models driven by a Markovian dichotomic noise
Logistic growth models are recurrent in biology, epidemiology, market models,
and neural and social networks. They find important applications in many other
fields including laser modelling. In numerous realistic cases the growth rate
undergoes stochastic fluctuations and we consider a growth model with a
stochastic growth rate modelled via an asymmetric Markovian dichotomic noise.
We find an exact analytical solution for the probability distribution providing
a powerful tool with applications ranging from biology to astrophysics and
laser physics
The non-causal origin of the black hole-galaxy scaling relations
We show that the black hole-bulge mass scaling relations observed from the
local to the high-z Universe can be largely or even entirely explained by a
non-causal origin, i.e. they do not imply the need for any physically coupled
growth of black hole and bulge mass, for example through feedback by active
galactic nuclei (AGN). Provided some physics for the absolute normalisation,
the creation of the scaling relations can be fully explained by the
hierarchical assembly of black hole and stellar mass through galaxy merging,
from an initially uncorrelated distribution of BH and stellar masses in the
early Universe. We show this with a suite of dark matter halo merger trees for
which we make assumptions about (uncorrelated) black hole and stellar mass
values at early cosmic times. We then follow the halos in the presence of
global star formation and black hole accretion recipes that (i) work without
any coupling of the two properties per individual galaxy and (ii) correctly
reproduce the observed star formation and black hole accretion rate density in
the Universe. With disk-to-bulge conversion in mergers included, our
simulations even create the observed slope of ~1.1 for the
M_BH-M_bulge-relations at z=0. This also implies that AGN feedback is not a
required (though still a possible) ingredient in galaxy evolution. In light of
this, other mechanisms that can be invoked to truncate star formation in
massive galaxies are equally justified.Comment: Accepted for publication in ApJ; accepted version; again expanded, 13
pages, 8 figures; now also with BH-halo prediction
A Kennicutt-Schmidt Law for Intervening Absorption Line Systems
We argue that most strong intervening metal absorption line systems, where
the rest equivalent width of the MgII 2796A line is >0.5A, are interstellar
material in, and outflowing from, star-forming disks. We show that a version of
the Kennicutt-Schmidt law is readily obtained if the MgII equivalent widths are
interpreted as kinematic broadening from absorbing gas in outflowing winds
originating from star-forming galaxies. Taking a phenomenological approach and
using a set of observational constraints available for star-forming galaxies,
we are able to account for the density distribution of strong MgII absorbers
over cosmic time. The association of intervening material with star-forming
disks naturally explains the metallicity and dust content of strong MgII
systems as well as their high HI column densities, and does not require the
advection of metals from compact star-forming regions into the galaxy halos to
account for the observations. We find that galaxies with a broad range of
luminosities can give rise to absorption of a given rest-equivalent width, and
discuss possible observational strategies to better quantify true
galaxy-absorber associations and further test our model. We show that the
redshift evolution in the density of absorbers closely tracks the star
formation history of the universe and that strong intervening systems can be
used to directly probe the physics of both bright and faint galaxies over a
broad redshift range. By identifying strong intervening systems with galaxy
disks and quantifying a version of the Kennicutt-Schmidt law that applies to
them, a new probe of the interstellar medium is found which provides
complementary information to that obtained through emission studies of
galaxies. Implications of our results for galaxy feedback and enrichment of the
intergalactic medium are discussed. [abridged]Comment: 23 pages, 15 figure
The MgII Cross-section of Luminous Red Galaxies
We describe a search for MgII(2796,2803) absorption lines in Sloan Digital
Sky Survey (SDSS) spectra of QSOs whose lines of sight pass within impact
parameters of 200 kpc of galaxies with photometric redshifts of z=0.46-0.6 and
redshift errors Delta z~0.05. The galaxies selected have the same colors and
luminosities as the Luminous Red Galaxy (LRG) population previously selected
from the SDSS. A search for Mg II lines within a redshift interval of +/-0.1 of
a galaxy's photometric redshift shows that absorption by these galaxies is
rare: the covering fraction is ~ 10-15% between 20 and 100 kpc, for Mg II lines
with rest equivalent widths of Wr >= 0.6{\AA}, falling to zero at larger
separations. There is no evidence that Wr correlates with impact parameter or
galaxy luminosity. Our results are consistent with existing scenarios in which
cool Mg II-absorbing clouds may be absent near LRGs because of the environment
of the galaxies: if LRGs reside in high-mass groups and clusters, either their
halos are too hot to retain or accrete cool gas, or the galaxies themselves -
which have passively-evolving old stellar populations - do not produce the
rates of star formation and outflows of gas necessary to fill their halos with
Mg II absorbing clouds. In the rarer cases where Mg II is detected, however,
the origin of the absorption is less clear. Absorption may arise from the
little cool gas able to reach into cluster halos from the intergalactic medium,
or from the few star-forming and/or AGN-like LRGs that are known to exist.Comment: Accepted by ApJ; minor correction
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Scaling relations of z ∼ 0.25–1.5 galaxies in various environments from the morpho-kinematics analysis of the MAGIC sample
Context. The evolution of galaxies is influenced by many physical processes, which may vary depending on their environment. Aims. We combine Hubble Space Telescope (HST) and Multi-Unit Spectroscopic Explorer (MUSE) data of galaxies at 0.25-1.5 to probe the impact of environment on the size-mass relation, the main sequence (MS) relation, and the Tully-Fisher relation (TFR). Methods. We perform a morpho-kinematics modelling of 593 [O-II] emitters in various environments in the COSMOS area from the MUSE-gAlaxy Groups In Cosmos survey. The HST F814W images are modelled with a bulge-disk decomposition to estimate their bulge-disk ratio, effective radius, and disk inclination. We use the [O-II]λλ3727, 3729 doublet to extract the galaxies ionised gas kinematics maps from the MUSE cubes, and we model those maps for a sample of 146 [O-II] emitters, including bulge and disk components constrained from morphology and a dark matter halo. Results. We find an offset of 0.03 dex (1 significant) on the size-mass relation zero point between the field and the large structure sub-samples, with a richness threshold of N=10 to separate between small and large structures, and of 0.06 dex (2) with N=20. Similarly, we find a 0.1 dex (2A) difference on the MS relation with N=10 and 0.15 dex (3) with N=20. These results suggest that galaxies in massive structures are smaller by 14% and have star formation rates reduced by a factor of 1.31.5 with respect to field galaxies at z 0.7. Finally, we do not find any impact of the environment on the TFR, except when using N=20 with an offset of 0.04 dex (1). We discard the effect of quenching for the largest structures, which would lead to an offset in the opposite direction. We find that, at z0.7, if quenching impacts the mass budget of galaxies in structures, these galaxies would have been affected quite recently and for roughly 0.7-+1.5 Gyr. This result holds when including the gas mass but vanishes once we include the asymmetric drift correction
On the Kennicutt-Schmidt relation of low-metallicity high-redshift galaxies
We present results of self-consistent, high-resolution cosmological
simulations of galaxy formation at z~3. The simulations employ recently
developed recipe for star formation based on the local abundance of molecular
hydrogen, which is tracked self-consistently during the course of simulation.
The phenomenological H2 formation model accounts for the effects of
dissociating UV radiation of stars in each galaxy, as well as self-shielding
and shielding of H2 by dust, and therefore allows us to explore effects of
lower metallicities and higher UV fluxes prevalent in high redshift galaxies on
their star formation. We compare stellar masses, metallicities, and star
formation rates of the simulated galaxies to available observations of the
Lyman Break Galaxies (LBGs) and find a reasonable agreement. We find that the
Kennicutt-Schmidt (KS) relation exhibited by our simulated galaxies at z~3 is
substantially steeper and has a lower amplitude than the z=0 relation at
Sigma_gas < 100 Msun/pc^2. The predicted relation, however, is consistent with
existing observational constraints for the z~3 Damped Lyman (DLA) and
LBGs. Our tests show that the main reason for the difference from the local KS
relation is lower metallicity of the ISM in high redshift galaxies. We discuss
several implications of the metallicity-dependence of the KS relation for
galaxy evolution and interpretation of observations.Comment: Submitted to Ap
Quasars probing intermediate redshift star-forming galaxies
We present a sample of 46 [OIII]-emitting galaxies at z<0.8 detected in the
fibre spectra of quasars from the SDSS-DR7 through an automatic search
procedure. We also detect [OII] and Hb emission lines from most of these
galaxies in the SDSS spectra. We study both the emission and absorption
properties of a sub-sample of 17 galaxies in the redshift range z=0.4-0.7,
where MgII lines are covered by the SDSS spectra. The measured lower-limits on
the star-formation rates of these galaxies are in the range 0.2-20 M_sun/yr.
The emission line luminosities and (O/H) metallicities from R23 measured in
this sample are similar to what is found in normal galaxies at these redshifts.
Thus, this constitutes a unique sample of intermediate redshift star-forming
galaxies where we can study the QSO absorber - galaxy connection. Strong MgII
(W>1A) as well as MgI absorption lines are detected in the QSO spectra at the
redshift of most of these galaxies. Strong FeII (W>1A) absorption lines are
also generally detected whenever the appropriate wavelength ranges are covered.
This suggests that most of these systems could be bona-fide Damped Lyman-alpha
systems. We investigate various possible relations between the MgII rest
equivalent widths and the emission line properties. We find a possible (2
sigma) correlation between the emission-line metallicity of the galaxies and
the MgII rest equivalent width of the absorbers [truncated].Comment: 15 pages, 11 figures, 5 tables. accepted for publication in MNRA
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