120 research outputs found
Gas Dynamics and Star Formation in the Galaxy Pair NGC1512/1510
(abridged) Here we present HI line and 20-cm radio continuum data of the
nearby galaxy pair NGC1512/1510 as obtained with the Australia Telescope
Compact Array. These are complemented by GALEX UV-, SINGG Halpha- and Spitzer
mid-infrared images, allowing us to compare the distribution and kinematics of
the neutral atomic gas with the locations and ages of the stellar clusters
within the system. For the barred, double-ring galaxy NGC1512 we find a very
large HI disk, about 4x its optical diameter, with two pronounced spiral/tidal
arms. Both its gas distribution and the distribution of the star-forming
regions are affected by gravitational interaction with the neighbouring blue
compact dwarf galaxy NGC1510. The two most distant HI clumps, at radii of about
80 kpc, show signs of star formation and are likely tidal dwarf galaxies. Star
formation in the outer disk of NGC1512 is revealed by deep optical- and
two-color ultraviolet images. Using the latter we determine the properties of
about 200 stellar clusters and explore their correlation with dense HI clumps
in the even larger 2XHI disk. The multi-wavelength analysis of the NGC1512/1510
system, which is probably in the first stages of a minor merger having started
about 400 Myr ago, links stellar and gaseous galaxy properties on scales from
one to 100 kpc.Comment: accepted in MNRAS (please find the high-resolution pdf file and
further information at http://www.atnf.csiro.au/people/bkoribal/ngc1512
Persistence of hazard fecal bacteria for public health in a stream at the municipality of Aguazul Casanare
This study comes from a pollution case under an administrative point of view, but mainly this study targets to establish the spatial range which this pollutionreaches on the territory, serving to set further studies on where has to be measured its socioeconomical effects. The case´ scenario is a punctual discharge of wastewater from the municipal depurator facility on a natural stream. The pollution was traced by the amount of fecal coliforms in water samples at ten sampling points along the stream course. Was evaluated the water suspended bacteria (planktonic coliforms) and the attached bacteria to submerged surfaces (benthic coliforms), looking for a mathematical model to describe its behavior. There along the stream was observed a decreasing trend on planktonic coliforms by a dilution effect, but also was observed an increasing trend on benthic coliforms, indicating that these bacteria can be persistent in theaquatic ecosystem under this life form (biofilm). This pollution reaches near to7km downstream from the spill-pipe discharge, where along this course there are many users of this water, mainly for crops irrigation. Furthermore was observed livestock animals grazing on the stream. All this implicates an irregular situation according to environmental normative about waters, also can causes administrative problems to the municipality because this pollution can risk public health to downstream inhabitants and workers with diseases
Morphological Transformations of Galaxies in the A901/02 Supercluster from STAGES
We present a study of galaxies in the Abell 901/902 Supercluster at z~0.165,
based on HST ACS F606W, COMBO-17, Spitzer 24um, XMM-Newton X-ray, and
gravitational lensing maps, as part of the STAGES survey. We characterize
galaxies with strong externally-triggered morphological distortions and normal
relatively undisturbed galaxies, using visual classification and quantitative
CAS parameters. We compare normal and distorted galaxies in terms of their
frequency, distribution within the cluster, star formation properties, and
relationship to dark matter (DM) or surface mass density, and intra-cluster
medium (ICM) density. We revisit the morphology density relation, which
postulates a higher fraction of early type galaxies in dense environments, by
considering separately galaxies with a low bulge-to-disk (B/D) ratio and a low
gas content as these two parameters may not be correlated in clusters. We
report here on our preliminary analysis.Comment: To appear in the ASP conference proceedings of the "Frank N. Bash
Symposium 2007: New Horizons in Astronomy", Eds. A. Frebel, J. Maund, J.
Shen, M. Siegel. 4 pages, 4 figure
A VLT VIMOS integral field spectroscopic study of perturbed blue compact galaxies: UM 420 and UM 462
We report on optical integral field spectroscopy of two unrelated blue
compact galaxies mapped with the 13 x 13 arcsec^2 VIMOS integral field unit at
a resolution of 0.33 x 0.33 arcsec^2. Continuum and background subtracted
emission line maps in the light of [O III] 5007, H-alpha, and [N II] 6584 are
presented. Both galaxies display signs of ongoing perturbation and/or
interaction. UM 420 is resolved for the first time to be a merging system
composed of two starbursting components with an 'arm-like' structure associated
with the largest component. UM 462 which is a disrupted system of irregular
morphology is resolved into at least four starbursting regions. Maps of the
H-alpha radial velocity and FWHM are discussed. No underlying broad line region
was detected from either galaxy as the emission lines are well-fitted with
single Gaussian profiles only. Electron temperatures and densities as well as
the abundances of helium, oxygen, nitrogen, and sulphur were computed from
spectra integrated over the whole galaxies and for each area of recent star
formation. Maps of the O/H ratio are presented: these galaxies show oxygen
abundances that are ~20 per cent solar. No evidence of substantial abundance
variations across the galaxies that would point to significant nitrogen or
oxygen self-enrichment is found (<0.2 dex limit). Contrary to previous
observations, this analysis does not support the classification of these BCGs
as Wolf-Rayet galaxies as the characteristic broad emission line features have
not been detected in our spectra. Baldwin-Phillips-Terlevich emission line
ratio diagrams which were constructed on a pixel by pixel basis indicate that
the optical spectra of these systems are predominantly excited by stellar
photoionization.Comment: 19 pages, 14 figure
Bipolar disorder comorbid with alcohol use disorder: focus on neurocognitive correlates
Bipolar disorder (BD) and alcohol use disorders (AUDs) are usually comorbid, and both have been associated with significant neurocognitive impairment. Patients with the BD-AUD comorbidity (dual diagnosis) may have more severe neurocognitive deficits than those with a single diagnosis, but there is paucity of research in this area. To explore this hypothesis more thoroughly, we carried out a systematic literature review through January 2015. Eight studies have examined the effect of AUDs on the neurocognitive functioning of BD patients. Most studies found that BD patients with current or past history of comorbid AUDs show more severe impairments, especially in verbal memory and executive cognition, than their non-dual counterparts. Greater neurocognitive dysfunction is another facet of this severe comorbid presentation. Implications for clinical practice and research are discussed. Specifically, the application of holistic approaches, such as clinical staging and systems biology, may open new avenues of discoveries related to the BD-AUD comorbidity
A reference time scale for Site U1385 (Shackleton Site) on the SW Iberian Margin
Variations in sediment color contain very strong precession signals at Site U1385, and the amplitude modulation of these cycles provides a powerful tool for developing an orbitally-tuned age model. We tuned the U1385 record by correlating peaks in L* to the local summer insolation maxima at 37°N. The benthic δ18O record of Site U1385, when placed on the tuned age model, generally agrees with other time scales within their respective chronologic uncertainties.
The age model is transferred to down-core data to produce a continuous time series of log(Ca/Ti) that reflect relative changes of biogenic carbonate and detrital sediment. Biogenic carbonate increases during interglacial and interstadial climate states and decreases during glacial and stadial periods. Much of the variance in the log(Ca/Ti) is explained by a linear combination of orbital frequencies (precession, tilt and eccentricity), whereas the residual signal reflects suborbital climate variability. The strong correlation between suborbital log(Ca/Ti) variability and Greenland temperature over the last glacial cycle at Site U1385 suggests that this signal can be used as a proxy for millennial-scale climate variability over the past 1.5 Ma.
Millennial climate variability, as expressed by log(Ca/Ti) at Site U1385, was a persistent feature of glacial climates over the past 1.5 Ma, including glacial periods of the early Pleistocene (‘41-kyr world’) when boundary conditions differed significantly from those of the late Pleistocene (‘100-kyr world’). Suborbital variability was suppressed during interglacial stages and enhanced during glacial periods, especially when benthic δ18O surpassed ~ 3.3–3.5‰. Each glacial inception was marked by appearance of strong millennial variability and each deglaciation was preceded by a terminal stadial event. Suborbital variability may be a symptomatic feature of glacial climate or, alternatively, may play a more active role in the inception and/or termination of glacial cycles
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