4,898 research outputs found
The Phoenix Deep Survey: The 1.4 GHz microJansky catalogue
The initial Phoenix Deep Survey (PDS) observations with the Australia
Telescope Compact Array have been supplemented by additional 1.4 GHz
observations over the past few years. Here we present details of the
construction of a new mosaic image covering an area of 4.56 square degrees, an
investigation of the reliability of the source measurements, and the 1.4 GHz
source counts for the compiled radio catalogue. The mosaic achieves a 1-sigma
rms noise of 12 microJy at its most sensitive, and a homogeneous radio-selected
catalogue of over 2000 sources reaching flux densities as faint as 60 microJy
has been compiled. The source parameter measurements are found to be consistent
with the expected uncertainties from the image noise levels and the Gaussian
source fitting procedure. A radio-selected sample avoids the complications of
obscuration associated with optically-selected samples, and by utilising
complementary PDS observations including multicolour optical, near-infrared and
spectroscopic data, this radio catalogue will be used in a detailed
investigation of the evolution in star-formation spanning the redshift range 0
< z < 1. The homogeneity of the catalogue ensures a consistent picture of
galaxy evolution can be developed over the full cosmologically significant
redshift range of interest. The 1.4 GHz mosaic image and the source catalogue
are available on the web at http://www.atnf.csiro.au/~ahopkins/phoenix/ or from
the authors by request.Comment: 16 pages, 11 figures, 4 tables. Accepted for publication by A
Suplementação mineral para bovinos de corte no Pantanal (Sub-região da Nhecolândia).
Os levantamentos de concentrações de minerais nas pastagens e nos tecidos de bovinos feitos em algumas sub-regiões do Pantanal indicaram ocorrência de deficiências acentuadas, principalmente de cálcio e fósforo. Baseado nesse trabalho, a Embrapa Pantanal elaborou cinco fórmulas de suplemento mineral para diferentes sub-regiões do Pantanal
Do fiscal imbalances deteriorate sovereign debt ratings ?
We use sovereign debt rating estimations from Afonso, Gomes and Rother (2009, 2011) for Fitch, Moody’s, and Standard & Poor’s, to assess to what extent the recent fiscal imbalances are being reflected on the sovereign debt notations. With macro and fiscal data up to 2010, and macro and fiscal projections, we obtain the expected rating for several OECD countries. The answer to the title question is yes, but in a diverse way for each country. Our average model predictions point to a heterogeneous behaviour of rating agencies across countries
Radio observations of the CDF-South: a possible link between radio emission and star formation in X-ray selected AGN
We explore the nature of the radio emission of X-ray selected AGN by
combining deep radio (1.4GHz; 60micro-Jy) and X-ray data with multiwavelength
(optical, mid-infrared) observations in the Extended Chandra Deep Field South
(E-CDFS). The fraction of radio detected X-ray sources increases from 9% in the
E-CDFS to 14% in the central region of this field, which has deeper X-ray
coverage from the 1Ms CDFS. We find evidence that the radio emission of up to
60% of the hard X-ray/radio matched AGN is likely associated with
star-formation in the host galaxy. Firstly, the mid-IR (24micron) properties of
these sources are consistent with the infrared/radio correlation of starbursts.
Secondly, most of them are found in galaxies with blue rest-frame optical
colours (U-V), suggesting a young stellar population. On the contrary,
X-ray/radio matched AGN which are not detected in the mid-infrared have red U-V
colours suggesting their radio emission is associated with AGN activity. We
also find no evidence for a population of heavily obscured radio-selected AGN
that are not detected in X-rays. Finally, we do no confirm previous claims for
a correlation between radio emission and X-ray obscuration. Assuming that the
radio continuum measures star-formation, this finding is against models where
the dust and gas clouds associated with circumnuclear starbursts are
spherically blocking our view to the central engine.Comment: Accepted by A&
A Tale of Two Souths: microsatellite assessment of the role Portuguese Salmo salar populations play in Europe
Tese de mestrado, Biologia da Conservação, 2022, Universidade de Lisboa, Faculdade de CiênciasAtlantic salmon (Salmo salar L.) is an anadromous species with homing behaviour. Generally,
individuals from this species are born in freshwater systems, migrate to feeding grounds in North
Atlantic and return to their birthplace to reproduce. This reproductive isolation potentiates local
adaptation. In recent years, Atlantic salmon populations in Europe have experienced great declines and
are now classified as Vulnerable (VU). In Portugal, very little is known about this species, but this
species is classified as Critically Endangered (CR), the highest threatened status. In this work, 14
microsatellite loci are used to assess population structure, migratory patterns and genetic diversity of 28
already identified and analysed populations (Gilbey et al., 2018), plus two additional populations, one
from Galicia, Spain (Lerez River) and the other from Portuguese Minho basin (Mouro River). This is
the first work to analyse Portuguese Atlantic salmon population’s genetics. The goal of the present study
was to assess if the Portuguese populations were genetically distinguishable from other European
populations. This work described a new Iberian genetic cluster, which is pointed out by several analysis
(namely, STRUCTURE, PCoA and POPTREE2). This new group has a similar degree of differentiation
from the Main European clusters as the Icelandic cluster that was described in previous works. Another
important discovery described was the high relatedness among populations from Portugal and Galicia,
when compared with the Asturian population, all located in the Iberian Peninsula. The genetic diversity
analysis showed that the genetic uniqueness of each population is decreasing if compared to other works.
The estimates of population effective size (Ne) indicate low Ne in most of the populations. It concludes
that future genetic approaches to this species must consider this new Iberian cluster. On the other side,
more studies must be done to fully understand the correlation between Iberian populations (in particular,
northwestern coast populations and northern coast populations). It is also highlighted the necessity of
management measures, for Portuguese populations since they are the most threatened populations
The Phoenix Deep Survey: spectroscopic catalog
The Phoenix Deep Survey is a multi-wavelength survey based on deep 1.4 GHz
radio imaging, reaching well into the sub-100 microJy level. One of the aims of
this survey is to characterize the sub-mJy radio population, exploring its
nature and evolution. In this paper we present the catalog and results of the
spectroscopic observations aimed at characterizing the optically ``bright''
(R<~ 21.5 mag) counterparts of faint radio sources. Out of 371 sources with
redshift determination, 21% have absorption lines only, 11% show AGN
signatures, 32% are star-forming galaxies, 34% show narrow emission lines that
do not allow detailed spectral classification (due to poor signal-to-noise
ratio and/or lack of diagnostic emission lines) and the remaining 2% are
identified with stars. For the star-forming galaxies with a Balmer decrement
measurement we find a median extinction of A(Ha)=1.9 mag, higher than that of
optically selected samples. This is a result of the radio selection, which is
not biased against dusty systems. Using the available spectroscopic
information, we estimate the radio luminosity function of star-forming galaxies
in two independent redshift bins at z~0.1 and 0.3 respectively. We find direct
evidence for strong luminosity evolution of these systems consistent with L(1.4
GHz) ~ (1+z)^(2.7).Comment: 39 pages, 12 figures. References added, and minor changes to reflect
published versio
The Phoenix Deep Survey: X-ray properties of faint radio sources
In this paper we use a 50ks XMM-Newton pointing overlapping with the Phoenix
Deep Survey, a homogeneous radio survey reaching muJy sensitivities, to explore
the X-ray properties and the evolution of star-forming galaxies. UV, optical
and NIR photometry is available and is used to estimate photometric redshifts
and spectral types for radio sources brighter than R=21.5mag (total of 82).
Sources with R<21.5mag and spiral galaxy SEDs (34) are grouped into two
redshift bins with a median of z=0.240 and 0.455 respectively. Stacking
analysis for both the 0.5-2 and 2-8keV bands is performed on these subsamples.
A high confidence level signal (>3.5sigma) is detected in the 0.5-2keV band
corresponding to a mean flux of ~3e-16cgs for both subsamples. This flux
translates to mean luminosities of ~5e40 and 1.5e41cgs for the z=0.240 and
0.455 subsamples respectively. Only a marginally significant signal (2.6sigma)
is detected in the 2-8keV band for the z=0.455 subsample. We argue that the
stacked signal above is dominated by star-formation. The mean L_X/L_B ratio and
the mean L_X of the two subsamples are found to be higher than optically
selected spirals and similar to starbursts. We also find that the mean L_X and
L_1.4 of the faint radio sources studied here are consistent with the L_X-L_1.4
correlation of local star-forming galaxies. Moreover, the X-ray emissivity of
sub-mJy sources to z~0.3 is found to be elevated compared to local HII
galaxies. The observed increase is consistent with L_X evolution of the form
(1+z)^3. Assuming that our sample is indeed dominated by starbursts this is
direct evidence for evolution of such systems at X-ray wavelengths. Using an
empirical L_X to SFR conversion we estimate a global SFR density at z~0.3 of
\~0.029M_o/yr/Mpc in agreement with previous studies.Comment: 12 pages, 6 figures, accepted for publication in MNRA
Flowing bodies: Exploring the micro and macro scales of bodily interactions with urban media installations
In this paper we investigate human interactions with urban media installations by adopting two scales of analysis: the body scale (micro) and the city scale (macro). This twofold approach allows us to better understand the relationships between the design properties of outdoor installations and the urban spatial layout around them. We conducted in-the-wild studies of two urban media installations, one consisting of fixed components, and the other of movable components, which were deployed in different places and encouraged different types of whole-body interaction. We provide a detailed account of the micro and macro levels of interactions, based on observational and qualitative explorations. Our studies reveal that the urban spatial layout is a key element in defining the interactions and encounters around outdoor interfaces, and therefore it needs to inform the design process from the outset
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