152 research outputs found
Cartographie T1 par séquences d'échos stimulés et Look-Locker avec pulses pseudo-adiabatiques en imagerie par résonance magnétique
ThÚse numérisée par la Direction des bibliothÚques de l'Université de Montréal
Discovery of a New Member of the Inner Oort Cloud from The Next Generation Virgo Cluster Survey
We report the discovery of 2010 GB, a likely new member of the Inner
Oort Cloud (IOC). 2010 GB is one of 91 Trans Neptunian Objects (TNOs)
and Centaurs discovered in a 76 deg contiguous region imaged as part of the
Next Generation Virgo Cluster Survey (NGVS) --- a moderate ecliptic latitude
survey reaching a mean limiting magnitude of --- using
MegaPrime on the 3.6m Canada France Hawaii Telescope. 2010 GB is found
to have an orbit with semi-major axis AU, inclination and pericentre AU. This is the second largest
perihelion distance among known solar system objects. Based on the sky coverage
and depth of the NGVS, we estimate the number of IOC members with sizes larger
than 300 km ( mag) to be . A comparison of the
detection rate from the NGVS and the PDSSS (a characterized survey that
`re-discovered' the IOC object Sedna) gives, for an assumed a power-law LF for
IOC objects, a slope of , with only two detections
in this region this slope estimate is highly uncertain.Comment: 20 pages, 3 figures, 1 table. Accepted for publication in The
Astrophysical Journal Letter
Galaxies at the extremes: Ultra-diffuse galaxies in the Virgo Cluster
We report the discovery of three large (R29 >~ 1 arcminute) extremely low
surface brightness (mu_(V,0) ~ 27.0) galaxies identified using our deep,
wide-field imaging of the Virgo Cluster from the Burrell Schmidt telescope.
Complementary data from the Next Generation Virgo Cluster Survey do not resolve
red giant branch stars in these objects down to i=24, yielding a lower distance
limit of 2.5 Mpc. At the Virgo distance, these objects have half-light radii
3-10 kpc and luminosities L_V=2-9x10^7 Lsun. These galaxies are comparable in
size but lower in surface brightness than the large ultradiffuse LSB galaxies
recently identified in the Coma cluster, and are located well within Virgo's
virial radius; two are projected directly on the cluster core. One object
appears to be a nucleated LSB in the process of being tidally stripped to form
a new Virgo ultracompact dwarf galaxy. The others show no sign of tidal
disruption, despite the fact that such objects should be most vulnerable to
tidal destruction in the cluster environment. The relative proximity of Virgo
makes these objects amenable to detailed studies of their structural properties
and stellar populations. They thus provide an important new window onto the
connection between cluster environment and galaxy evolution at the extremes.Comment: 7 pages, 4 figures, to appear in ApJ Letters. Updated with minor
revisions to match accepted versio
Galaxies at the extremes: Ultra-diffuse galaxies in the Virgo Cluster
We report the discovery of three large (R29 >~ 1 arcminute) extremely low
surface brightness (mu_(V,0) ~ 27.0) galaxies identified using our deep,
wide-field imaging of the Virgo Cluster from the Burrell Schmidt telescope.
Complementary data from the Next Generation Virgo Cluster Survey do not resolve
red giant branch stars in these objects down to i=24, yielding a lower distance
limit of 2.5 Mpc. At the Virgo distance, these objects have half-light radii
3-10 kpc and luminosities L_V=2-9x10^7 Lsun. These galaxies are comparable in
size but lower in surface brightness than the large ultradiffuse LSB galaxies
recently identified in the Coma cluster, and are located well within Virgo's
virial radius; two are projected directly on the cluster core. One object
appears to be a nucleated LSB in the process of being tidally stripped to form
a new Virgo ultracompact dwarf galaxy. The others show no sign of tidal
disruption, despite the fact that such objects should be most vulnerable to
tidal destruction in the cluster environment. The relative proximity of Virgo
makes these objects amenable to detailed studies of their structural properties
and stellar populations. They thus provide an important new window onto the
connection between cluster environment and galaxy evolution at the extremes.Comment: 7 pages, 4 figures, to appear in ApJ Letters. Updated with minor
revisions to match accepted versio
Draft Genome Sequence of a Necrotoxigenic Escherichia coli Isolate
Here, we present the draft genome sequence of a necrotoxigenic Escherichia coli strain isolated from a patient following a very rapidly evolving, lethal necrotizing fasciitis
Case Report First Report of Clostridium lavalense Isolated in Human Blood Cultures
An 88-year-old man was admitted to the hospital with worsening malaise, fever, and weakness. Anaerobic blood culture bottles revealed the presence of an anaerobic, Gram-positive sporulated bacillus. Empirical antibiotherapy with intravenous piperacillintazobactam was initiated. The patient defervesced after four days and was switched to oral amoxicillin on his 6th day of antibiotic therapy and later discharged from the hospital. Four months later, he had recovered. The bacterium was initially identified as Clostridium butyricum using anaerobic manual identification panel. 16S rRNA gene sequence and phylogenetic analysis showed the bacterium to be Clostridium lavalense, a recently described species with no previously published case of isolation in human diagnostic samples so far. This is the first report of Clostridium lavalense isolation from human blood cultures. Further studies are needed in order to elucidate the role of Clostridium lavalense in human disease and its virulence factors
The Most Massive Ultra-Compact Dwarf Galaxy in the Virgo Cluster
We report on the properties of the most massive ultra-compact dwarf galaxy
(UCD) in the nearby Virgo Cluster of galaxies using imaging from the Next
Generation Virgo Cluster Survey (NGVS) and spectroscopy from Keck/DEIMOS. This
object (M59-UCD3) appears to be associated with the massive Virgo galaxy M59
(NGC 4621), has an integrated velocity dispersion of 78 km/s, a dynamical mass
of , and an effective radius () of 25 pc. With an
effective surface mass density of , it is the
densest galaxy in the local Universe discovered to date, surpassing the density
of the luminous Virgo UCD, M60-UCD1. M59-UCD3 has a total luminosity of
mag, and a spectral energy distribution consistent with an old
(14 Gyr) stellar population with [Fe/H]=0.0 and [/Fe]=+0.2. We also
examine deep imaging around M59 and find a broad low surface brightness stream
pointing towards M59-UCD3, which may represent a tidal remnant of the UCD
progenitor. This UCD, along with similar objects like M60-UCD1 and M59cO,
likely represents an extreme population of tidally stripped galaxies more akin
to larger and more massive compact early-type galaxies than to nuclear star
clusters in present-day dwarf galaxies.Comment: 6 pages, 4 figures, 1 table, accepted for publication in ApJ Letter
Low-concentration methylene blue maintains energy production and strongly improves survival of leigh syndrome french canadian skin fibroblasts
Leigh syndrome French Canadian (LSFC) is a recessive disease caused by mutations in the LRPPRC gene (leucine-rich pentatricopeptide repeat containing protein). These mutations induce a cytochrome c oxidase (COX) deficiency resulting in episodes of acute acidotic crisis that will often lead to death. There is no effective treatment. Methylene blue (MB) is a redox dye that increases COX content and activity in vitro and in vivo suggesting that MB could prevent and treat LSFC. In this study, the protective effect of low-concentration MB was tested on two LSFC cell lines, including LSFC-F1, homozygous for the mutation A354V, and LSFC-F2 a compound heterozygous for the mutations A354V and C12775STOP. MB effect on metabolic activity was assessed on both LSFC cells in stable and acidotic conditions. For LSFC-F1, results showed that metabolic activity drastically decline after 96 hours in both conditions but not LSFC-F2 and normal cells. MB completely prevents the decrease of metabolic activity in LSFC-F1. Intracellular ATP content was also measured in both culture media. After 96 hours in acidotic medium, ATP content was almost completely depleted for both LSFC cells. Interestingly, MB completely restores ATP content in LSFC-F1 and LSFC-F2 cells. Finally, MB strongly improves the survival of both LSFC cells. This article is open to POST-PUBLICATION REVIEW. Registered readers (see âFor Readersâ) may comment by clicking on ABSTRACT on the issueâs contents page
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