5,012 research outputs found
CO line emission in the halo of a radio galaxy at z=2.6
We report the detection of luminous CO(3-2) line emission in the halo of the
z=2.6 radio galaxy (HzRG) TXS0828+193, which has no detected counterpart at
optical to mid-infrared wavelengths implying a stellar mass < few x10^9 M_sun
and relatively low star-formation rates. With the IRAM PdBI we find two CO
emission line components at the same position at ~80 kpc distance from the HzRG
along the axis of the radio jet, with different blueshifts of few 100 km s^-1
relative to the HzRG and a total luminosity of ~2x10^10 K km s^-1 pc^2 detected
at 8 sigma significance. HzRGs have significant galaxy overdensities and
extended halos of metal-enriched gas often with embedded clouds or filaments of
denser material, and likely trace very massive dark-matter halos. The CO
emission may be associated with a gas-rich, low-mass satellite galaxy with
little on-going star formation, in contrast to all previous CO detections of
galaxies at similar redshifts. Alternatively, the CO may be related to a gas
cloud or filament and perhaps jet-induced gas cooling in the outer halo,
somewhat in analogy with extended CO emission found in low-redshift galaxy
clusters.Comment: MNRAS Letters, accepte
PKS2250-41: a case study for triggering
We present the results of a multiwavelength study of the z = 0.31 radio
source PKS2250-41. Integral field unit and long-slit spectroscopy obtained
using VIMOS and FORS1 on the VLT, and archival HST optical imaging observations
are used to study the morphology, kinematics and ionisation state of the
extended emission line region (EELR) surrounding this source, and also a
companion galaxy at a similar redshift. Near-infrared imaging observations
obtained using the NTT are used to analyse the underlying galaxy morphologies.
The EELR displays a complex variety of different gas kinematics and ionization
states, consistent with a mixture of radio source shocks and AGN
photoionization. The radio galaxy is likely to lie within a group environment,
and is plausibly undergoing interactions with one or more other objects. The
disk-like galaxy to the northeast of the radio source lies at a similar
redshift to the radio galaxy itself, and has its major axis position angle
aligned with the filamentary continuum and line emission extending outwards
from the radio galaxy. This filamentary structure is most plausibly interpreted
as a tidal structure associated with an interaction involving the radio source
host galaxy and the aligned companion galaxy to the north-east; this encounter
may have potentially triggered the current epoch of radio source activity.
Overall, PKS2250-41 displays some of the best evidence that radio source
activity can be triggered in this manner. [abridged]Comment: 16 pages, 13 figures (some colour). Accepted for publication in
MNRAS. Abstract abridge
Spin-polarization-induced structural selectivity in Pd and Pt () compounds
Spin-polarization is known to lead to important {\it magnetic} and {\it
optical} effects in open-shell atoms and elemental solids, but has rarely been
implicated in controlling {\it structural} selectivity in compounds and alloys.
Here we show that spin-polarized electronic structure calculations are crucial
for predicting the correct crystal structures for Pd and Pt
compounds. Spin-polarization leads to (i) stabilization of the structure
over the structure in PtCr, PdCr, and PdMn, (ii) to the
stabilization of the structure over the structure in PdCo
and to (iii) ordering (rather than phase-separation) in PtCo and PdCr.
The results are analyzed in terms of first-principles local spin density
calculations.Comment: 4 pages, REVTEX, 3 eps figures, to appear in PR
The self-assembly and evolution of homomeric protein complexes
We introduce a simple "patchy particle" model to study the thermodynamics and
dynamics of self-assembly of homomeric protein complexes. Our calculations
allow us to rationalize recent results for dihedral complexes. Namely, why
evolution of such complexes naturally takes the system into a region of
interaction space where (i) the evolutionarily newer interactions are weaker,
(ii) subcomplexes involving the stronger interactions are observed to be
thermodynamically stable on destabilization of the protein-protein interactions
and (iii) the self-assembly dynamics are hierarchical with these same
subcomplexes acting as kinetic intermediates.Comment: 4 pages, 4 figure
First results of the ROSEBUD Dark Matter experiment
Rare Objects SEarch with Bolometers UndergrounD) is an experiment which
attempts to detect low mass Weak Interacting Massive Particles (WIMPs) through
their elastic scattering off Al and O nuclei. It consists of three small
sapphire bolometers (of a total mass of 100 g) with NTD-Ge sensors in a
dilution refrigerator operating at 20 mK in the Canfranc Underground
Laboratory. We report in this paper the results of several runs (of about 10
days each) with successively improved energy thresholds, and the progressive
background reduction obtained by improvement of the radiopurity of the
components and subsequent modifications in the experimental assembly, including
the addition of old lead shields. Mid-term plans and perspectives of the
experiment are also presented.Comment: 14 pages, 8 figures, submitted to Astroparticle Physic
Characterization of bipartite states using a single homodyne detector
We suggest a scheme to reconstruct the covariance matrix of a two-mode state
using a single homodyne detector plus a polarizing beam splitter and a
polarization rotator. It can be used to fully characterize bipartite Gaussian
states and to extract relevant informations on generic states.Comment: 7 pages, 1 figur
Diverse phytoplasmas associated with maize bushy stunt disease in Peru
Corn plants showing symptoms of midribs
chlorosis, and leaf reddening, short internodes, ear pro-
liferation, and plant growth reduction were collected in
Peru from fields in nine localities in the provinces of
Huancayo, Chupaca, and Jauja in the Junín region, and
tested to verify phytoplasma presence and identity.
Primers amplifying the phytoplasma ribosomal 16S
and ribosomal protein genes were used. The phytoplas-
ma presence was detected in symptomatic samples from
all the surveyed areas. The sequencing of the obtained
amplicons indicated the presence of ‘Candidatus Phy-
toplasma asteris’ and ‘Ca. P. pruni’-related strains. A
BLASTn search of sequenced genes showed that the
two ‘Candidatus Phytoplasma’ strains identified in corn
shares 100% and 99.82% identity with the ‘Ca. P.
asteris’ strains from maize and 99.92% and 99.55%
with ‘Ca. P. pruni’-related strains, respectively. The
RFLP analyses allowed to enclose these phytoplasma
strains in the 16SrI-B and 16SrIII-J subgroups; howev-
er, the two phytoplasmas were, in some cases, present in
mixed infection. The 16SrIII-J phytoplasma is for the
first time reported associated with the maize bushy stunt
disease and this represent a relevant information for the
disease epidemiology towards its appropriate manage-
ment in the affected area
Propagação vegetativa de pitaia vermelha em resposta a profundidade de plantio e dominância apical.
A produção de mudas de qualidade é condição fundamental para o sucesso de uma boa produção agrícola, o que justifica o estudo da propagação por estaquia, para facilitar o estabelecimento em novas áreas cultivadas
Controlling suction by vapour equilibrium technique at different temperatures, application to the determination of the water retention properties of MX80 clay
Problems related to unsaturated soils are frequently encountered in
geotechnical or environmental engineering works. In most cases, for the purpose
of simplicity, the problems are studied by considering the suction effects on
volume change or shear strength under isothermal conditions. Under isothermal
condition, very often, a temperature independent water retention curve is
considered in the analysis, which is obviously a simplification. When the
temperature changes are too significant to be neglected, it is necessary to
account for the thermal effects. In this paper, a method for controlling
suction using the vapour equilibrium technique at different temperatures is
presented. First, calibration of various saturated saline solutions was carried
out from temperature of 20 degrees C to 60 degrees C. A mirror psychrometer was
used for the measurement of relative humidity generated by saturated saline
solutions at different temperatures. The results obtained are in good agreement
with the data from the literature. This information was then used to determine
the water retention properties of MX80 clay, which showed that the retention
curve is shifting down with increasing of temperature
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