276 research outputs found
Um olhar sobre o novo: Orkut é ferramenta de pesquisa
Verifica a pertinência do uso do site de relacionamentos “Orkut” como ferramenta adicional de pesquisa de mercado. Primeiramente, o estudo aborda de que forma a necessidade de informação é fundamental como parte do processo de busca para uma comunicação eficiente. Procura então entender a pesquisa como fonte principal, organizada e legitimada, na obtenção dessas informações. A seguir, o estudo traz um panorama de como a Internet está mudando, discute novos conceitos como “Web 2.0” e “antropologia virtual” e busca entender novas ferramentas como blogs e comunidades virtuais. Através de entrevistas com profissionais do mercado que lidam com pesquisa, leituras afins e observação, o trabalho busca definir, traçar um histórico, rever a importância e ilustrar usos do site de
relacionamentos “Orkut”, discutindo a seguir seus métodos, usos, vantagens e por outro lado riscos e limites como ferramenta de pesquisa, traçando paralelos com métodos tradicionais
First Results from the XMM-Newton Slew Survey
We have attempted to analyse all the available data taken by XMM-Newton as it
slews between targets. This slew survey, the resultant source catalogue and the
analysis procedures used are described in an accompanying paper. In this letter
we present the initial science results from the survey. To date, detailed
source-searching has been performed in three X-ray bands (soft, hard and total)
in the EPIC-pn 0.2-12 keV band over ~6300 sq.degrees (~15% of the sky), and of
order 4000 X-ray sources have been detected (~55% of which have IDs). A great
variety of sources are seen, including AGN, galaxies, clusters and groups,
active stars, SNRs, low- and high-mass XRBs and white dwarfs. In particular, as
this survey constitutes the deepest ever hard-band 2-12 keV all-sky survey, a
large number of hard sources are detected. Furthermore, the great sensitivity
and low-background of the EPIC-pn camera are especially suited to emission from
extended sources, and interesting spatial structure is observed in many
supernova remnants and clusters of galaxies. The instrument is very adept at
mapping large areas of the X-ray sky. Also, as the slew survey is well matched
to the ROSAT all-sky survey, long-term variability studies are possible, and a
number of extremely variable X-ray sources, some possibly due to the tidal
disruption of stars by central supermassive black holes, have been discovered.Comment: 4 Pages, 3 Figs, to appear in PASJ (2006) 58, No 6. Colour version
available at http://www.star.le.ac.uk/~amr30/publications.htm
The Herschel PACS photometer calibration - A time dependent flux calibration for the PACS chopped point-source photometry AOT mode
We present a flux calibration scheme for the PACS chopped point-source
photometry observing mode based on the photometry of five stellar standard
sources. This mode was used for science observations only early in the mission.
Later, it was only used for pointing and flux calibration measurements. Its
calibration turns this type of observation into fully validated data products
in the Herschel Science Archive. Systematic differences in calibration with
regard to the principal photometer observation mode, the scan map, are derived
and amount to 5-6%. An empirical method to calibrate out an apparent response
drift during the first 300 Operational Days is presented. The relative
photometric calibration accuracy (repeatability) is as good as 1% in the blue
and green band and up to 5% in the red band. Like for the scan map mode,
inconsistencies among the stellar calibration models become visible and amount
to 2% for the five standard stars used. The absolute calibration accuracy is
therefore mainly limited by the model uncertainty, which is 5% for all three
bands.Comment: 20 pages, 7 pages of appendix, 11 figures, accepted to appear in
Experimental Astronomy, Special Issue for Herschel Calibrations based on the
"Herschel Calibration Workshop: Only the Best Data Products for the Legacy
Archive", held at ESAC, 25 - 27 March 2013,
http://herschel.esac.esa.int/CalibrationWorkshop5.shtm
The reversal of the SF-density relation in a massive, X-ray selected galaxy cluster at z=1.58: results from Herschel
Dusty, star-forming galaxies have a critical role in the formation and
evolution of massive galaxies in the Universe. Using deep far-infrared imaging
in the range 100-500um obtained with the Herschel telescope, we investigate the
dust-obscured star formation in the galaxy cluster XDCP J0044.0-2033 at z=1.58,
the most massive cluster at z >1.5, with a measured mass M200= 4.7x10
Msun. We perform an analysis of the spectral energy distributions (SEDs) of 12
cluster members (5 spectroscopically confirmed) detected with >3
significance in the PACS maps, all ULIRGs. The individual star formation rates
(SFRs) lie in the range 155-824 Ms/yr, with dust temperatures of 2435 K.
We measure a strikingly high amount of star formation (SF) in the cluster core,
SFR ( 1875158 Ms/yr, 4x higher than the amount of star
formation in the cluster outskirts. This scenario is unprecedented in a galaxy
cluster, showing for the first time a reversal of the SF-density relation at
z~1.6 in a massive cluster.Comment: Letter accepted for publication in MNRAS, ESA Press Release on 18
December 201
Star formation in the cluster CLG0218.3-0510 at z=1.62 and its large-scale environment: the infrared perspective
The galaxy cluster CLG0218.3-0510 at z=1.62 is one of the most distant galaxy
clusters known, with a rich muti-wavelength data set that confirms a mature
galaxy population already in place. Using very deep, wide area (20x20 Mpc)
imaging by Spitzer/MIPS at 24um, in conjunction with Herschel 5-band imaging
from 100-500um, we investigate the dust-obscured, star-formation properties in
the cluster and its associated large scale environment. Our galaxy sample of
693 galaxies at z=1.62 detected at 24um (10 spectroscopic and 683 photo-z)
includes both cluster galaxies (i.e. within r <1 Mpc projected clustercentric
radius) and field galaxies, defined as the region beyond a radius of 3 Mpc. The
star-formation rates (SFRs) derived from the measured infrared luminosity range
from 18 to 2500 Ms/yr, with a median of 55 Ms/yr, over the entire radial range
(10 Mpc). The cluster brightest FIR galaxy, taken as the centre of the galaxy
system, is vigorously forming stars at a rate of 25670 Ms/yr, and the
total cluster SFR enclosed in a circle of 1 Mpc is 116196 Ms/yr. We
estimate a dust extinction of about 3 magnitudes by comparing the SFRs derived
from [OII] luminosity with the ones computed from the 24um fluxes. We find that
the in-falling region (1-3 Mpc) is special: there is a significant decrement
(3.5x) of passive relative to star-forming galaxies in this region, and the
total SFR of the galaxies located in this region is lower (130 Ms/yr/Mpc2) than
anywhere in the cluster or field, regardless of their stellar mass. In a
complementary approach we compute the local galaxy density, Sigma5, and find no
trend between SFR and Sigma5. However, we measure an excess of star-forming
galaxies in the cluster relative to the field by a factor 1.7, that lends
support to a reversal of the SF-density relation in CLG0218.Comment: accepted for publication in MNRAS. v2: minor correction
The Pointing System of the Herschel Space Observatory. Description, Calibration, Performance and Improvements
We present the activities carried out to calibrate and characterise the
performance of the elements of attitude control and measurement on board the
Herschel spacecraft. The main calibration parameters and the evolution of the
indicators of the pointing performance are described, from the initial values
derived from the observations carried out in the performance verification phase
to those attained in the last year and half of mission, an absolute pointing
error around or even below 1 arcsec, a spatial relative pointing error of some
1 arcsec and a pointing stability below 0.2 arsec. The actions carried out at
the ground segment to improve the spacecraft pointing measurements are
outlined. On-going and future developments towards a final refinement of the
Herschel astrometry are also summarised. A brief description of the different
components of the attitude control and measurement system (both in the space
and in the ground segments) is also given for reference. We stress the
importance of the cooperation between the different actors (scientists, flight
dynamics and systems engineers, attitude control and measurement hardware
designers, star-tracker manufacturers, etc.) to attain the final level of
performance.Comment: 28 pages, 8 figures, accepted for publication in Experimental
Astronom
The Benefits of Using XML Technologies in Astronomical Data Retrieval and Interpretation
This paper describes a solution found during recent research that could provide improvements in the efficiency, reliability and cost of retrieving stored astronomical data. This solution uses XML Technologies in showing that when querying a variety of astronomical data sources a standardised data structure can be output into an XML query results Document. This paper shows the astronomical XMLSchema that has been partially developed in conjunction with simple custom supporting system software. It also discusses briefly possible future implications
Shmt2: a stat3 signaling new player in prostate cancer energy metabolism
Prostate cancer (PCa) is a multifactorial disease characterized by the aberrant activity of different regulatory pathways. STAT3 protein mediates some of these pathways and its activation is implicated in the modulation of several metabolic enzymes. A bioinformatic analysis indicated a STAT3 binding site in the upstream region of SHMT2 gene. We demonstrated that in LNCaP, PCa cells' SHMT2 expression is upregulated by the JAK2/STAT3 canonical pathway upon IL-6 stimulation. Activation of SHTM2 leads to a decrease in serine levels, pushing PKM2 towards the nuclear compartment where it can activate STAT3 in a non-canonical fashion that in turn promotes a transient shift toward anaerobic metabolism. These results were also confirmed on FFPE prostate tissue sections at different Gleason scores. STAT3/SHMT2/PKM2 loop in LNCaP cells can modulate a metabolic shift in response to inflammation at early stages of cancer progression, whereas a non-canonical STAT3 activation involving the STAT3/HIF-1α/PKM2 loop is responsible for the maintenance of Warburg effect distinctive of more aggressive PCa cells. Chronic inflammation might thus prime the transition of PCa cells towards more advanced stages, and SHMT2 could represent a missing factor to further understand the molecular mechanisms responsible for the transition of prostate cancer towards a more aggressive phenotyp
The cosmological analysis of X-ray cluster surveys: II- Application of the CR-HR method to the XMM archive
We have processed 2774 high-galactic observations from the XMM archive (as of
May 2010) and extracted a serendipitous catalogue of some 850 clusters of
galaxies based on purely X-ray criteria, following the methodology developed
for the XMM-LSS survey. Restricting the sample to the highest signal-to-noise
objects (347 clusters), we perform a cosmological analysis using the X-ray
information only. The analysis consists in the modelling of the observed
colour-magnitude (CR-HR) diagram constructed from cluster instrumental
count-rates measured in the [0.5-2], [1-2] and [0.5-1] keV bands. A MCMC
procedure simultaneously fits the cosmological parameters, the evolution of the
cluster scaling laws and the selection effects. Our results are consistent with
the sigma_8 and Omega_m values obtained by WMAP-5 and point toward a negative
evolution of the cluster scaling relations with respect to the self-similar
expectation. We are further able to constrain the cluster fractional radius
xc0=r_c/r500c, to xc0=0.24 +/- 0.04. This study stresses again the critical
role of selection effects in deriving cluster scaling relations, even in the
local universe. Finally, we show that CR-HR method applied to the eRosita
all-sky survey - provided that cluster photometric redshifts are available -
will enable the determination of the equation of state of the dark energy at
the level of the DETF stage IV predictions; simultaneously, the evolution of
the cluster scaling-relations will be unambiguously determined. The XMM CLuster
Archive Super Survey (XCLASS) serendipitous cluster catalogue is available
online at: http://xmm-lss.in2p3.fr:8080/l4sdb/.Comment: 26 pages, 24 figures, 9 tables. Accepted for publication in MNRAS
(minor changes with respect to submitted version). The corresponding galaxy
cluster catalogue is available at http://xmm-lss.in2p3.fr:8080/l4sdb
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