104 research outputs found
The VMC Survey -- XXXIV. Morphology of Stellar Populations in the Magellanic Clouds
The Magellanic Clouds are nearby dwarf irregular galaxies whose morphologies
show different properties when traced by different stellar populations, making
them an important laboratory for studying galaxy morphologies. We study the
morphology of the Magellanic Clouds using data from the VISTA survey of the
Magellanic Clouds system (VMC). We used about and million sources
across an area of deg and deg towards the Large and
Small Magellanic Cloud (LMC and SMC), respectively. We estimated median ages of
stellar populations occupying different regions of the near-infrared
() colour-magnitude diagram. Morphological maps
were produced and detailed features in the central regions were characterised
for the first time with bins corresponding to a spatial resolution of
kpc (LMC) and kpc (SMC). In the LMC, we find that main sequence stars
show coherent structures that grow with age and trace the multiple spiral arms
of the galaxy, star forming regions become dimmer as we progress in age, while
supergiant stars are centrally concentrated. Intermediate-age stars, despite
tracing a regular and symmetrical morphology, show central clumps and hints of
spiral arms. In the SMC, young main sequence stars depict a broken bar.
Intermediate-age populations show signatures of elongation towards the
Magellanic Bridge that can be attributed to the LMC-SMC interaction
Myr ago. They also show irregular central features suggesting that the inner
SMC has also been influenced by tidal interactions.Comment: Accepted for publication in MNRAS, 20 pages, 12 figures and 2 table
The intrinsic reddening of the Magellanic Clouds as traced by background galaxies -- II. The Small Magellanic Cloud
We present a map of the total intrinsic reddening across ~34 deg of the
Small Magellanic Cloud (SMC) derived using optical () and near-infrared
(IR; ) spectral energy distributions (SEDs) of background
galaxies. The reddening map is created using a subsample of 29,274 galaxies
with low levels of intrinsic reddening based on the LePhare
minimisation SED-fitting routine. We find statistically significant enhanced
levels of reddening associated with the main body of the SMC compared with
regions in the outskirts [ mag]. A comparison with
literature reddening maps of the SMC shows that, after correcting for
differences in the volume of the SMC sampled, there is good agreement between
our results and maps created using young stars. In contrast, we find
significant discrepancies between our results and maps created using old stars
or based on longer wavelength far-IR dust emission that could stem from biased
samples in the former and uncertainties in the far-IR emissivity and the
optical properties of the dust grains in the latter. This study represents one
of the first large-scale categorisations of extragalactic sources behind the
SMC and as such we provide the LePhare outputs for our full sample of ~500,000
sources.Comment: Accepted for publication in MNRAS, 13 pages, 6 figures and 4 tables.
Tables 1, 3 and 4 will be available in full as Supporting Information in the
online version of the articl
Protocol for a randomized, double blind, placebo controlled, crossover trial of Melatonin for treatment of Nocturia in adults with Multiple Sclerosis (MeNiMS)
© 2017 The Author(s). Background: Nocturia (the symptom of needing to wake up to pass urine) is common in progressive Multiple Sclerosis (MS) patients. Moderate-to-severe nocturia affects quality of life, can exacerbate fatigue and may affect capacity to carry out daily activities. Melatonin is a natural hormone regulating circadian cycles, released by the pineal gland at night-time, and secretion is impaired in MS. Melatonin levels can be supplemented by administration in tablet form at bedtime. The aim of this study is to evaluate the effect of melatonin on mean number of nocturia episodes per night in MS patients. Secondary outcome measures will assess impact upon quality of life, urinated volumes, lower urinary tract symptoms (LUTS), cognition, sleep quality and sleep disturbance of partners. Methods: A randomized, double blind, placebo controlled, crossover trial consisting of two, six week treatment phases (active drug melatonin 2 mg or placebo), with a 1 month wash-out period in between. The primary outcome (change in nocturia episodes per night) in this two arm, two treatment, two period crossover design, will be objectively measured using frequency volume charts (FVC) at baseline and following both treatment phases. Questionnaires will be used to assess quality of life, sleep quality, safety and urinary tract symptoms. Qualitative interviews of participants and partners will explore issues including quality of life, mechanisms of sleep disturbance and impact of nocturia on partners. Discussion: This study will evaluate whether melatonin reduces the frequency of nocturia episodes in MS patients, and therefore whether 'Circadin' has the potential to reduce LUTS and fatigue, and improve cognition and overall quality of life. Trial registration: (EudraCT reference) 2012-00418321 registered: 25/01/13. ISRCTN Registry: ISRCTN3868786
4MOST Scientific Operations
The 4MOST instrument is a multi-object spectrograph that will address
Galactic and extragalactic science cases simultaneously by observing targets
from a large number of different surveys within each science exposure. This
parallel mode of operation and the survey nature of 4MOST require some distinct
4MOST-specific operational features within the overall operations model of ESO.
The main feature is that the 4MOST Consortium will deliver, not only the
instrument, but also contractual services to the user community, which is why
4MOST is also described as a facility. This white paper concentrates on
information particularly useful to answering the forthcoming Call for Letters
of Intent.Comment: Part of the 4MOST issue of The Messenger, published in preparation of
4MOST Community Workshop, see http://www.eso.org/sci/meetings/2019/4MOST.htm
Future mmVLBI Research with ALMA: A European vision
Very long baseline interferometry at millimetre/submillimetre wavelengths
(mmVLBI) offers the highest achievable spatial resolution at any wavelength in
astronomy. The anticipated inclusion of ALMA as a phased array into a global
VLBI network will bring unprecedented sensitivity and a transformational leap
in capabilities for mmVLBI. Building on years of pioneering efforts in the US
and Europe the ongoing ALMA Phasing Project (APP), a US-led international
collaboration with MPIfR-led European contributions, is expected to deliver a
beamformer and VLBI capability to ALMA by the end of 2014 (APP: Fish et al.
2013, arXiv:1309.3519).
This report focuses on the future use of mmVLBI by the international users
community from a European viewpoint. Firstly, it highlights the intense science
interest in Europe in future mmVLBI observations as compiled from the responses
to a general call to the European community for future research projects. A
wide range of research is presented that includes, amongst others:
- Imaging the event horizon of the black hole at the centre of the Galaxy
- Testing the theory of General Relativity an/or searching for alternative
theories
- Studying the origin of AGN jets and jet formation
- Cosmological evolution of galaxies and BHs, AGN feedback
- Masers in the Milky Way (in stars and star-forming regions)
- Extragalactic emission lines and astro-chemistry
- Redshifted absorption lines in distant galaxies and study of the ISM and
circumnuclear gas
- Pulsars, neutron stars, X-ray binaries
- Testing cosmology
- Testing fundamental physical constantsComment: Replaced figures 2 and 3: corrected position SRT. Corrected minor
typo in 5.
Fluoxetine during Development Reverses the Effects of Prenatal Stress on Depressive-Like Behavior and Hippocampal Neurogenesis in Adolescence
Depression during pregnancy and the postpartum period is a growing health problem, which affects up to 20% of women. Currently, selective serotonin reuptake inhibitor (SSRIs) medications are commonly used for treatment of maternal depression. Unfortunately, there is very little research on the long-term effect of maternal depression and perinatal SSRI exposure on offspring development. Therefore, the aim of this study was to determine the role of exposure to fluoxetine during development on affective-like behaviors and hippocampal neurogenesis in adolescent offspring in a rodent model of maternal depression. To do this, gestationally stressed and non-stressed Sprague-Dawley rat dams were treated with either fluoxetine (5 mg/kg/day) or vehicle beginning on postnatal day 1 (P1). Adolescent male and female offspring were divided into 4 groups: 1) prenatal stress+fluoxetine exposure, 2) prenatal stress+vehicle, 3) fluoxetine exposure alone, and 4) vehicle alone. Adolescent offspring were assessed for anxiety-like behavior using the Open Field Test and depressive-like behavior using the Forced Swim Test. Brains were analyzed for endogenous markers of hippocampal neurogenesis via immunohistochemistry. Results demonstrate that maternal fluoxetine exposure reverses the reduction in immobility evident in prenatally stressed adolescent offspring. In addition, maternal fluoxetine exposure reverses the decrease in hippocampal cell proliferation and neurogenesis in maternally stressed adolescent offspring. This research provides important evidence on the long-term effect of fluoxetine exposure during development in a model of maternal adversity
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