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A comprehensive biovigilance programme was undertaken in 2018 to monitor potential insect vectors of viruses of grapevines (Vitis vinifera; Vitaceae) in two vineyards in Québec. Two hundred seventy-four insects were collected using yellow sticky traps and sweeping nets. Collected specimens were first classified into orders, with special attention given to the Hemiptera order, which is the main group of virus vectors. Hemipteran pests were identified to species. Among these specimens, one adult of Rossmoneura tecta McAtee (Hemiptera: Cicadellidae) was identified, the first report of this species in Canada. Empoasca vincula DeLong, Erythroneura acuticephala Robinson, and Erythroneura cymbium McAtee, three other species belonging to the same family and previously reported in other Canadian provinces, were also identified for the first time in Québec. Further investigations are being undertaken to test the ability of these species to transmit grapevine viruses.
Weaning is known to induce important nutritional and energetic stress in piglets. Low-birthweight (LBW) piglets, now frequently observed in swine production, are more likely to be affected. The weaning period is also associated with dysfunctional immune responses, uncontrolled inflammation and oxidative stress conditions that are recognized risk factors for infections and diseases. Mounting evidence indicates that mitochondria, the main cellular sources of energy in the form of adenosine 5′ triphosphate (ATP) and primary sites of reactive oxygen species production, are related to immunity, inflammation and bacterial pathogenesis. However, no information is currently available regarding the link between mitochondrial energy production and oxidative stress in weaned piglets. The objective of this study was to characterize markers of cellular and mitochondrial energy metabolism and oxidative status in both normal-birthweight (NBW) and LBW piglets throughout the peri-weaning period. To conduct the study, 30 multiparous sows were inseminated and litters were standardized to 12 piglets. All the piglets were weighted at day 1 and 120 piglets were selected and assigned to 1 of 2 experimental groups: NBW (n = 60, mean weight of 1.73 ± 0.01 kg) and LBW piglets weighing less than 1.2 kg (n = 60, 1.01 ± 0.01 kg). Then, 10 piglets from each group were selected at 14, 21 (weaning), 23, 25, 29 and 35 days of age to collect plasma and organ (liver, intestine and kidney) samples. Analysis revealed that ATP concentrations were lower in liver of piglets after weaning than during lactation (P < 0.05) thus suggesting a significant impact of weaning stress on mitochondrial energy production. Oxidative damage to DNA (8-hydroxy-2′-deoxyguanosine, 8-OHdG) and proteins (carbonyls) measured in plasma increased after weaning and this coincides with a rise in enzymatic antioxidant activity of glutathione peroxidase (GPx) and superoxide dismutase (SOD) (P < 0.05). Mitochondrial activities of both GPx and SOD are also significantly higher (P < 0.05) in kidney of piglets after weaning. Additionally, oxidative damage to macromolecules is more important in LBW piglets as measured concentrations of 8-OHdG and protein carbonyls are significantly higher (P < 0.05) in plasma and liver samples, respectively, than for NBW piglets. These results provide novel information about the nature, intensity and duration of weaning stress by revealing that weaning induces mitochondrial dysfunction and cellular oxidative stress conditions which last for at least 2 weeks and more severely impact smaller piglets.
We started a systematic search for periodic variable-star candidates in the EROS-2 database in the context of preparatory work for the Gaia satellite mission. The goal is to evaluate different classification tools and strategies, and to identify a large sample of variable candidates. In this paper we present the results of an assessment study of a three-step identification and classification process. In the study we took a sample of about 80,000 stars from one of the LMC EROS fields.
We have started a survey of M 33 in order to find variable stars and
Cepheids in particular. We have obtained more than 30 epochs of
g'r'i' data with the CFHT and the
one-square-degree camera MegaCam. We present first results from this
survey, including the search for variable objects and a basic
characterization of the various groups of variable stars.
DOME C is advocated as being currently the best astronomical site on Earth, with an excellent duty cycle,
excellent seeing (provided that the instrumentation is above the $\sim $30 m boundary layer), low scintillation,
low infra red background. There is an opportunity for astronomy projects in the coming years at DOME C.
We will review here the case for the extrasolar planet searches. Both transit and microlensing searches
for extrasolar planets have a niche at DOME C, but the exact performances of such projects are strongly
dependent on the true quality of the site.
Transiting hot Jupiters could be efficiently detected thanks to the excellent duty
cycle at DOME C. The case of hot Neptunes is not clear.
Frozen 1–15 Earth mass planets are detectable with dedicated
microlensing operation, either by concentrating on a high
magnification events alerted by temperate sites, or a wide field
imager on a 2 m class telescope to simultaneously
detect and monitor microlensing events.
In order to run detailed simulations of observations of these
projects, we have a critical need of seeing statistics, and in particular
about the behavior of the boundary layer above the ice sheet and its
influence on the resulting seeing.
PLANET, the Probing Lensing Anomaly NETwork, is an international team
conducting observations of on-going gravitational microlensing
events from five sites in the southern hemisphere. Our primary goal is to
detect or to put constraints on sub-stellar companions of M dwarfs from the galactic disk.
We report the current status and discuss the future prospects.
A 2 m robotic telescope at Dome C which would benefit from continuous coverage and dream like seeing
(median of 0.27 arcsec) is currently the best option for a
ground based aggressive search for Earth-mass planets in the habitable zone.
Due to their extremely small luminosity compared to the stars they orbit, planets outside our own Solar System are extraordinarily difficult to detect directly in optical light. Careful photometric monitoring of distant stars, however, can reveal the presence of exoplanets via the microlensing or eclipsing effects they induce. The international PLANET collaboration is performing such monitoring using a cadre of semi-dedicated telescopes around the world. Their results constrain the number of gas giants orbiting 1–7 AU from the most typical stars in the Galaxy. Upgrades in the program are opening regions of “exoplanet discovery space” – toward smaller masses and larger orbital radii – that are inaccessible to the Doppler velocity technique.
We give an overview of the search and discovery of Sequence (PMS)
stars in the Magellanic Clouds. For the first time the
irregular optical brightness variability of Pre-Main Sequence stars,
generally attributed to variable dust obscuration of the central star,
has been used as an initial selection of young stellar objects.
We discuss 21 PMS candidates in the Large Magellanic Cloud (LMC)
and 7 PMS candidates in the Small Magellanic Cloud (SMC) detected
in this way. These stars have bolometric luminosities which
correspond to the most massive Galactic Herbig AeBe (HAeBe) stars, or even
The location of the LMC and SMC objects is correlated with
higher densities of cold interstellar dust as measured by IRAS in
the far infrared. We derive the fundamental parameters from
spectroscopy and find that there location in the HR-diagram would indicate
that the stars are more luminous when compared to Galactic HAeBe stars of
the same spectral type. There may be a trend with metallicity, in that the
SMC PMS stars can be even more luminous than the LMC PMS stars. It
indicates a possible increase of the proto-stellar accretion rate with
In the optical these HAeBe candidates have a higher probability
to be found in small (10 pc) clusters then other field stars of similar
colour and magnitude. We present a case study of a cluster around
one of the LMC HAeBe stars, using high resolution SUSI imaging. The
Hα-emitters detected in this cluster are also located in an
HR-diagram above the Galactic Palla-Stahler birthline corresponding to an
average protostellar mass accretion rate of 10-5 M⊙ yr-1.
We review the current status and future prospects of the PLANET collaboration, an international team of astronomers performing high-precision photometric monitoring of microlensing events. Our photometric precision and sampling is characterised and the suitability of the database for variable star studies is discussed. Preliminary results on K-giant stability are presented.
We present a status report of the original EROS and the on-going EROS-2 microlensing surveys, which were created to search for dark matter in the Galactic halo via microlensing effects on LMC/SMC stars. Microlensing surveys provide long-term systematic observations of millions of stars in both Clouds which yield a unique database of stellar photometry and variability. We review the results obtained on pulsating stars and detail the similarities and differences of the Magellanic Cloud Herbig Ae/Be stars with their Galactic counterparts.
It is well known that Cepheid variables are very important distance indicators because of their PL and PLC relations. The distances derived through the quoted relations are affected by well known systematic effects, since, in general, we have a poor knowledge of both reddening and metallicity of the Cepheid sample. Good estimates of the quoted parameters can be achieved if the observed Cepheids are cluster members since, by comparison between cluster CMD and theoretical isochrones we can estimate the cluster reddening, metallicity and age, i.e., the evolving masses for each evolutionary phase. The ideal objects to be searched for Cepheid membership are Magellanic Cloud clusters since they are well populated in the relevant evolutionary phases.
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