396 research outputs found
A monitoring tool for a GRID operation center
WorldGRID is an intercontinental testbed spanning Europe and the US
integrating architecturally different Grid implementations based on the Globus
toolkit. The WorldGRID testbed has been successfully demonstrated during the
WorldGRID demos at SuperComputing 2002 (Baltimore) and IST2002 (Copenhagen)
where real HEP application jobs were transparently submitted from US and Europe
using "native" mechanisms and run where resources were available, independently
of their location. To monitor the behavior and performance of such testbed and
spot problems as soon as they arise, DataTAG has developed the EDT-Monitor tool
based on the Nagios package that allows for Virtual Organization centric views
of the Grid through dynamic geographical maps. The tool has been used to spot
several problems during the WorldGRID operations, such as malfunctioning
Resource Brokers or Information Servers, sites not correctly configured, job
dispatching problems, etc. In this paper we give an overview of the package,
its features and scalability solutions and we report on the experience acquired
and the benefit that a GRID operation center would gain from such a tool.Comment: Talk from the 2003 Computing in High Energy and Nuclear Physics
(CHEP03), La Jolla, Ca, USA, March 2003, 3 pages, PDF. PSN MOET00
Drying and percolation in spatially correlated porous media
We study how the dynamics of a drying front propagating through a porous medium are affected by small-scale correlations in material properties. For this, we first present drying experiments in micro-fluidic micro-models of porous media. Here, the fluid pressures develop more intermittent dynamics as local correlations are added to the structure of the pore spaces. We also consider this problem numerically, using a model of invasion percolation with trapping, and find that there is a crossover in invasion behaviour associated with the length-scale of the disorder in the system. The critical exponents that describe large enough events are similar to the classic invasion percolation problem, while the addition of a finite correlation length significantly affects the exponent values of avalanches and bursts, up to some characteristic size. We thus find that even a weak local structure can interfere with the universality of invasion percolation phenomena. This has implications for a variety of multi-phase flow problems, such as drying, drainage, and fluid invasion
Resolved stellar population of distant galaxies in the ELT era
The expected imaging capabilities of future Extremely Large Telescopes (ELTs)
will offer the unique possibility to investigate the stellar population of
distant galaxies from the photometry of the stars in very crowded fields. Using
simulated images and photometric analysis we explore here two representative
science cases aimed at recovering the characteristics of the stellar
populations in the inner regions of distant galaxies. Specifically: case A) at
the center of the disk of a giant spiral in the Centaurus Group, (mu B~21,
distance of 4.6 Mpc); and, case B) at half of the effective radius of a giant
elliptical in the Virgo Cluster (mu~19.5, distance of 18 Mpc). We generate
synthetic frames by distributing model stellar populations and adopting a
representative instrumental set up, i.e. a 42 m Telescope operating close to
the diffraction limit. The effect of crowding is discussed in detail showing
how stars are measured preferentially brighter than they are as the confusion
limit is approached. We find that (i) accurate photometry (sigma~0.1,
completeness >90%) can be obtained for case B) down to I~28.5, J~27.5 allowing
us to recover the stellar metallicity distribution in the inner regions of
ellipticals in Virgo to within ~0.1 dex; (ii) the same photometric accuracy
holds for the science case A) down to J~28.0, K~27.0, enabling to reconstruct
of the star formation history up to the Hubble time via simple star counts in
diagnostic boxes. For this latter case we discuss the possibility of deriving
more detailed information on the star formation history from the analysis of
their Horizontal Branch stars. We show that the combined features of high
sensitivity and angular resolution of ELTs may open a new era for our knowledge
of the stellar content of galaxies of different morphological type up to the
distance of the Virgo cluster.Comment: 21 pages, 17 figures, PASP accepted in pubblicatio
Characterizing HR3549B using SPHERE
Aims. In this work, we characterize the low mass companion of the A0 field
star HR3549. Methods. We observed HR3549AB in imaging mode with the the NIR
branch (IFS and IRDIS) of SPHERE@VLT, with IFS in YJ mode and IRDIS in the H
band. We also acquired a medium resolution spectrum with the IRDIS long slit
spectroscopy mode. The data were reduced using the dedicated SPHERE GTO
pipeline, purposely designed for this instrument. We employed algorithms such
as PCA and TLOCI to reduce the speckle noise. Results. The companion was
clearly visible both with IRDIS and IFS.We obtained photometry in four
different bands as well as the astrometric position for the companion. Based on
our astrometry, we confirm that it is a bound object and put constraints on its
orbit. Although several uncertainties are still present, we estimate an age of
~100-150 Myr for this system, yielding a most probable mass for the companion
of 40-50MJup and T_eff ~300-2400 K. Comparing with template spectra points to a
spectral type between M9 and L0 for the companion, commensurate with its
position on the color-magnitude diagram.Comment: Accepted by A&A, 13 pages, 10 Figures (Figures 9 and 10 degraded to
reduce the dimension
INCIDÊNCIA FÚNGICA EM GLOMÉRULOS E SÂMARAS DE Casuarina equisetifolia (CASUARINACEAE)
The casuarina (Casuarina equisetifolia) is an angiosperm belonging to the family Casuarinaceae and is widely used in the establishment of dunes on the seafront, as windbreaks in orchards and in the recovery of degraded areas. However, it has presented problems with seedling mortality in nursery. Samaras can carry microorganisms on their surface or internally, constituting one of the main means of dissemination of plant pathogens. The objective of this study was to identify and evaluate the incidence of fungi associated with glomeruli and casuarina samaras. For this, we collected glomeruli and chambers from parent trees in Santa Maria-RS. In the laboratory, the glomeruli underwent a disinfestation process and were submitted to the filter paper sanity test. The samaras were also submitted to the same test, but comparing with and without asepsis. The experimental design was completely randomized and each treatment consisted of four replicates of 25 (glomeruli/samaras). Fusarium spp., Rhizoctonia spp., Alternaria spp., Pestalotiopsis spp., Phoma spp. and Colletotrichum spp. were found in both glomeruli and samaras, possibly indicating transmission from one to another. These fungi are known worldwide for causing diseases in seeds, seedlings and seedlings in nurseries of many forest species.A casuarina (Casuarina equisetifolia) é uma angiosperma que pertence à família Casuarinaceae e é largamente utilizada na fixação de dunas na orla marítima, como quebra-ventos em pomares e na recuperação de áreas degradadas. Entretanto, tem apresentado problemas com mortalidade de plântulas em viveiro. As sâmaras podem carregar microrganismos na sua superfície ou internamente, constituindo-se um dos principais meios de disseminação de patógenos de plantas. O presente trabalho teve por objetivo identificar e avaliar a incidência de fungos associados aos glomérulos e sâmaras de casuarina. Para isso, foram coletados glomérulos e sâmaras de árvores matrizes em Santa Maria–RS. No laboratório, os glomérulos passaram por um processo de desinfestação e foram submetidos ao teste de sanidade em papel filtro. As sâmaras também foram submetidas ao mesmo teste, porém comparando-as com e sem assepsia. O delineamento experimental foi o inteiramente casualizado e cada tratamento foi composto de quatro repetições de 25 (glomérulo/sâmara). Fusarium spp., Rhizoctonia spp., Alternaria spp., Pestalotiopsis spp., Phoma spp. e Colletotrichum spp. foram encontrados tanto em glomérulos como em sâmaras, indicando, possivelmente, a transmissão de um para outro. Esses fungos são conhecidos mundialmente por causarem doenças em sementes, plântulas e mudas em viveiro de muitas espécies florestais
Mancha-foliar-marrom da Nogueirapecã: Identificação e Manejo da Doença nos Pomares do Sul do Brasil.
bitstream/item/206988/1/COMUNICADO-TECNICO-373.pd
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