816 research outputs found
Automated microorganism Sample Collection Module
Modified Gelman Sampler obtains representative sample of microorganism population. Proposed Sample Collection Module is based on direct inoculation of selected solid growth media encased in a cartridge at all times except during inoculation. Cartridge can be handled with no danger of contamination to sample or operator
Binarity at the L/T brown dwarf transition
Current atmospheric models cannot reproduce some of the characteristics of
the transition between the L dwarfs with cloudy atmospheres and the T dwarfs
with dust-depleted photospheres. It has been proposed that a majority of the
L/T transition brown dwarfs could actually be a combinaison of a cloudy L dwarf
and a clear T dwarf. Indeed binarity seems to occur more frequently among L/T
transition brown dwarfs.
We aim to refine the statistical significance of the seemingly higher
frequency of binaries. Co-eval binaries would also be interesting test-beds for
evolutionary models. We obtained high-resolution imaging for six mid-L to
late-T dwarfs, with photometric distances between 8 and 33pc, using the
adaptive optics systems NACO at the VLT, and the Lick system, both with the
laser guide star.
We resolve none of our targets. Combining our data with published results, we
obtain a frequency of resolved L/T transition brown dwarfs of (31+21-15)%,
compared to (21+10-7)% and (14+14-7)% for mid-L and T dwarfs (90% of confidence
level). These fractions do not significantly support, nor contradict, the
hypothesis of a larger binary fraction in the L/T transition. None of our
targets has companions with effective temperatures as low as 360-1000K at
separations larger than 0.5".Comment: 6 pages, 4 figures, accepted by A&
Multiplicity of very low-mass objects in the Upper Scorpius OB association: a possible wide binary population
We report the initial results of a VLT/NACO high spatial resolution imaging
survey for multiple systems among 58 M-type members of the nearby Upper
Scorpius OB association. Nine pairs with separations below 100 have been
resolved. Their small angular separations and the similarity in the brightness
of the components (DMagK <1 for all of them), indicate there is a reasonable
likelihood several of them are true binaries rather than chance projections.
Follow-up imaging observations with WHT/LIRIS of the two widest binaries
confirm that their near-infrared colours are consistent with physical very low
mass binaries. For one of these two binaries, WHT/LIRIS spectra of each
component were obtained. We find that the two components have similar M6-M7
spectral types and signatures of low-gravity, as expected for a young brown
dwarf binary in this association. Our preliminary results indicate a possible
population of very low-mass binaries with semimajor axis in the range 100 AU
150 AU, which has not been seen in the Pleiades open cluster. If these
candidates are confirmed (one is confirmed by this work), these results would
indicate that the binary properties of very low-mass stars and brown dwarfs may
depend on the environment where they form.Comment: 11 pages, 1 table, 7 figures, request high resolution copies to
[email protected]
Victim-offender mediation and social work: focus groups with mediators in Flanders
The role of social work in the restorative justice field remains largely unexplored. This article reports on the findings of focus groups conducted with mediators of juvenile and adult mediation practices in Flanders (Belgium) to gain more insight into how mediators perceive their professional role and to what extent they refer to individual and structural dimensions of social work practice. Implications for future social work involvement and research are made
Resolved Hubble Space spectroscopy of ultracool binary systems
Using the low-resolution mode of the Space Telescope Imaging Spectrograph
(STIS) aboard the \emph{Hubble Space Telescope} (HST), we have obtained
spatially resolved spectra of 20 ultracool dwarfs. 18 of them belong to 9 known
very low-mass binary systems with angular separations in the range 0.37-0.098
arcseconds. We have derived spectral types in the range dM7.5 to dL6 from the
PC3 index, and by comparing our STIS spectra with ground-based spectra of
similar spectral resolution from Mart{\'\i}n et al. (1999). We have searched
for H emission in each object but it was clearly detected in only 2 of
them. We find that the distribution of H emission in our sample is
statistically different from that of single field dwarfs, suggesting an
intriguing anticorrelation between chromospheric activity and binarity for
M7--M9.5 dwarfs. We provide measuments of the strength of the main photospheric
features and the PC3 index, and we derive calibrations of spectral subclasses
versus F814W and K-band absolute magnitudes for a subset of 10 dwarfs in 5
binaries that have known trigonometric parallaxes.Comment: accepted for publication in A&
Morality tales: young women's narratives on offending, self-worth and desistance
This article emerges from a study of female offenders’ participation in police-facilitated restorative justice in one county in England. The qualitative study, presented here, is based on life history interviews with twelve women and focuses on three morality tales that emerged through narrative analysis: ‘offending as play,’ ‘the strong woman’ and ‘work and a normal life.’ The women used these tales to protect self-worth and justify ‘bad’ behavior in order to counter professional responses which they viewed as stigmatising. The paper concludes with implications for practice with girls and women who offend, which may benefit police, probation and social workers
Evidence for Divergent Evolution of Growth Temperature Preference in Sympatric Saccharomyces Species
The genus Saccharomyces currently includes eight species in addition to the model yeast Saccharomyces cerevisiae, most of which can be consistently isolated from tree bark and soil. We recently found sympatric pairs of Saccharomyces species, composed of one cryotolerant and one thermotolerant species in oak bark samples of various geographic origins. In order to contribute to explain the occurrence in sympatry of Saccharomyces species, we screened Saccharomyces genomic data for protein divergence that might be correlated to distinct growth temperature preferences of the species, using the dN/dS ratio as a measure of protein evolution rates and pair-wise species comparisons. In addition to proteins previously implicated in growth at suboptimal temperatures, we found that glycolytic enzymes were among the proteins exhibiting higher than expected divergence when one cryotolerant and one thermotolerant species are compared. By measuring glycolytic fluxes and glycolytic enzymatic activities in different species and at different temperatures, we subsequently show that the unusual divergence of glycolytic genes may be related to divergent evolution of the glycolytic pathway aligning its performance to the growth temperature profiles of the different species. In general, our results support the view that growth temperature preference is a trait that may have undergone divergent selection in the course of ecological speciation in Saccharomyces
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