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  • 11
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    Regulation of SPRY3 by X chromosome and PAR2-linked promoters in an autism susceptibility region (2015)
    Oxford University Press
    Details
    Publication Date: 2015-08-27
    Description: Sprouty proteins are regulators of cell growth and branching morphogenesis. Unlike mouse Spry3 , which is X-linked, human SPRY3 maps to the pseudoautosomal region 2; however, the human Y-linked allele is not expressed due to epigenetic silencing by an unknown mechanism. SPRY3 maps adjacent to X-linked Trimethyllysine hydroxylase epsilon ( TMLHE ), recently identified as an autism susceptibility gene. We report that Spry3 is highly expressed in central and peripheral nervous system ganglion cells in mouse and human, including cerebellar Purkinje cells and retinal ganglion cells. Transient over-expression or knockdown of Spry3 in cultured mouse superior cervical ganglion cells inhibits and promotes, respectively, neurite growth and branching. A 0.7 kb gene fragment spanning the human SPRY3 transcriptional start site recapitulates the endogenous Spry3 -expression pattern in LacZ reporter mice. In the human and mouse the SPRY3 promoter contains an AG-rich repeat and we found co-expression, and promoter binding and/or regulation of SPRY3 expression by transcription factors MAZ, EGR1, ZNF263 and PAX6. We identified eight alleles of the human SPRY3 promoter repeat in Caucasians, and similar allele frequencies in autism families. We characterized multiple SPRY3 transcripts originating at two CpG islands in the X-linked F8A3 — TMLHE region, suggesting X chromosome regulation of SPRY3 . These findings provide an explanation for differential regulation of X and Y-linked SPRY3 alleles. In addition, the presence of a SPRY3 transcript exon in a previously described X chromosome deletion associated with autism, and the cerebellar interlobular variation in Spry3 expression coincident with the reported pattern of Purkinje cell loss in autism, suggest SPRY3 as a candidate susceptibility locus for autism.
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
    Published by Oxford University Press
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  • 12
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    ATLASGAL - properties of compact H II regions and their natal clumps (2013)
    Oxford University Press
    Details
    Publication Date: 2013-09-17
    Description: We present a complete sample of molecular clumps containing compact and ultracompact H ii (UC H ii ) regions between  = 10° and 60° and | b | 〈 1°, identified by combining the APEX Telescope Large Area Survey of the Galaxy submm and CORNISH radio continuum surveys with visual examination of archival infrared data. Our sample is complete to optically thin, compact and UC H ii regions driven by a zero-age main-sequence star of spectral type B0 or earlier embedded within a 1000 M clump. In total we identify 213 compact and UC H ii regions, associated with 170 clumps. Unambiguous kinematic distances are derived for these clumps and used to estimate their masses and physical sizes, as well as the Lyman continuum fluxes and sizes of their embedded H ii regions. We find a clear lower envelope for the surface density of molecular clumps hosting massive star formation of 0.05 g cm –2 , which is consistent with a similar sample of clumps associated with 6.7 GHz masers. The mass of the most massive embedded stars is closely correlated with the mass of their natal clump. Young B stars appear to be significantly more luminous in the ultraviolet than predicted by current stellar atmosphere models. The properties of clumps associated with compact and UC H ii regions are very similar to those associated with 6.7 GHz methanol masers and we speculate that there is little evolution in the structure of the molecular clumps between these two phases. Finally, we identify a significant peak in the surface density of compact and UC H ii -regions associated with the W49A star-forming complex, noting that this complex is truly one of the most massive and intense regions of star formation in the Galaxy.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 13
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    Star formation scales and efficiency in Galactic spiral arms (2015)
    Oxford University Press
    Details
    Publication Date: 2015-07-04
    Description: We positionally match a sample of infrared-selected young stellar objects, identified by combining the Spitzer Galactic Legacy Infrared Mid-Plane Survey Extraordinaire, Wide-field Infrared Survey Explorer and Herschel Space Observatory Herschel infrared Galactic Plane Survey, to the dense clumps identified in the millimetre continuum by the Bolocam Galactic Plane Survey in two Galactic lines of sight centred towards l  = 30° and 40°. We calculate the ratio of infrared luminosity, L IR , to the mass of the clump, M clump , in a variety of Galactic environments and find it to be somewhat enhanced in spiral arms compared to the interarm regions when averaged over kiloparsec scales. We find no compelling evidence that these changes are due to the mechanical influence of the spiral arm on the star formation efficiency rather than, e.g. different gradients in the star formation rate due to patchy or intermittent star formation, or local variations that are not averaged out due to small source samples. The largest variation in L IR / M clump is found in individual clump values, which follow a lognormal distribution and have a range of over three orders of magnitude. This spread is intrinsic as no dependence of L IR / M clump with M clump was found. No difference was found in the luminosity distribution of sources in the arm and interarm samples and a strong linear correlation was found between L IR and M clump .
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 14
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    A distance-limited sample of massive star-forming cores from the RMS survey (2015)
    Oxford University Press
    Details
    Publication Date: 2015-07-09
    Description: We analyse C 18 O ( J  = 3–2) data from a sample of 99 infrared (IR)-bright massive young stellar objects (MYSOs) and compact H ii regions that were identified as potential molecular-outflow sources in the Red MSX Source survey. We extract a distance-limited ( D  〈 6 kpc) sample shown to be representative of star formation covering the transition between the source types. At the spatial resolution probed, Larson-like relationships are found for these cores, though the alternative explanation, that Larson's relations arise where surface-density-limited samples are considered, is also consistent with our data. There are no significant differences found between source properties for the MYSOs and H ii regions, suggesting that the core properties are established prior to the formation of massive stars, which subsequently have little impact at the later evolutionary stages investigated. There is a strong correlation between dust-continuum and C 18 O-gas masses, supporting the interpretation that both trace the same material in these IR-bright sources. A clear linear relationship is seen between the independently established core masses and luminosities. The position of MYSOs and compact H ii regions in the mass–luminosity plane is consistent with the luminosity expected from the most massive protostar in the cluster when using an ~40 per cent star formation efficiency and indicates that they are at a similar evolutionary stage, near the end of the accretion phase.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 15
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    A search for correlations between gamma-ray burst variability and afterglow onset (2015)
    Oxford University Press
    Details
    Publication Date: 2015-10-22
    Description: We compared the time (or time limit) of onset for optical afterglow emission to the -ray variability V in 76 gamma-ray bursts with redshifts. In the subset (25 cases) with the rise evident in the data, we fit the shape of the onset peak as well and compared the rising and decaying indices to V . We did not find any evidence for any patterns between these properties and there is no statistical support for any correlations. This indicates a lack of connection between irregularities of the prompt -ray emission and the establishment of the afterglow phase. In the ordinary prompt internal shocks interpretation, this would indicate a lack of relationship between V and the bulk Lorentz factor of the event.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 16
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    The prevalence of star formation as a function of Galactocentric radius (2016)
    Oxford University Press
    Details
    Publication Date: 2016-08-27
    Description: We present large-scale trends in the distribution of star-forming objects revealed by the Hi-GAL survey. As a simple metric probing the prevalence of star formation in Hi-GAL sources, we define the fraction of the total number of Hi-GAL sources with a 70 μm counterpart as the ‘star-forming fraction’ or SFF. The mean SFF in the inner galactic disc (3.1 kpc 〈 R GC 〈 8.6 kpc) is 25 per cent. Despite an apparent pile-up of source numbers at radii associated with spiral arms, the SFF shows no significant deviations at these radii, indicating that the arms do not affect the star-forming productivity of dense clumps either via physical triggering processes or through the statistical effects of larger source samples associated with the arms. Within this range of Galactocentric radii, we find that the SFF declines with R GC at a rate of –0.026 ±0.002 per kiloparsec, despite the dense gas mass fraction having been observed to be constant in the inner Galaxy. This suggests that the SFF may be weakly dependent on one or more large-scale physical properties of the Galaxy, such as metallicity, radiation field, pressure or shear, such that the dense sub-structures of molecular clouds acquire some internal properties inherited from their environment.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 17
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    Mid-infrared spectroscopy of SVS13: silicates, quartz and SiC in a protoplanetary disc (2015)
    Oxford University Press
    Details
    Publication Date: 2015-06-27
    Description: We present N -band (8–13 μm) spectroscopic observations of the low-mass, embedded pre-main-sequence close binary system SVS13. Absorption features are clearly detected which are attributable to amorphous silicates, crystalline forsterite, crystalline enstatite and annealed SiO 2 . Most intriguingly, a major component of the dust in the envelope or disc around SVS13 appears to be SiC, required to model adequately both the total intensity and polarization spectra. Silicon carbide is a species previously detected only in the spectra of C-rich evolved star atmospheres, wherein it is a dust condensate. It has not been unambiguously identified in the interstellar medium, and never before in a molecular cloud, let alone in close proximity to a forming star. Yet pre-solar grains of SiC have been identified in meteorites, possibly suggesting an interesting parallel between SVS13 and our own Solar-system evolution. The uniqueness of the spectrum suggests that we are either catching SVS13 in a short-lived evolutionary phase and/or that there is something special about SVS13 itself that makes it rare amongst young stars. We speculate on the physical origin of the respective dust species and why they are all simultaneously present towards SVS13. Two scenarios are presented: a disc-instability-induced fragmentation, with subsequent localized heating and orbital evolution first annealing initially amorphous silicates and then dispersing their crystalline products throughout a circumstellar disc; and a newly discovered shock-heating mechanism at the interface between the circumstellar and circumbinary discs providing the crystallization process. One or both of these mechanisms acting on carbon-rich grain material can also feasibly produce the SiC signature.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 18
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    Evaluating the profitability of selection cuts in irregular boreal forests: an approach based on Monte Carlo simulations (2012)
    Oxford University Press
    In: Forestry
    Details
    Publication Date: 2012-02-11
    Description: This study compares the financial return of converting old-growth boreal stands into even-aged stands to that of two approaches of selection cutting in Quebec (Canada). In this region, old-growth stands are usually harvested by completely removing the canopy while protecting the abundant advance regeneration, an approach known as careful logging around advance growth (CLAAG). These approaches were compared using a time frame of over 200 years. Consideration is given to the majority of the operating costs leading to end products. The financial analysis integrates Monte Carlo simulations, making it possible to consider the uncertainty associated with variables. The net present values (NPVs) are then associated with a distribution of probabilities. The results show that the probabilities of obtaining positive NPVs are high for all treatments, suggesting that selection cutting approaches can be appropriate alternatives to CLAAG for some stands. Depending on the criteria used, the CLAAG cut or one of the selection cuts show the best performances. In fact, the results of the financial study show that in the future, selection cutting approaches will be more profitable than CLAAG but still less than present CLAAG operations. This occurs because, according to the current yield curves and rotation ages, future stands managed with CLAAG will have smaller and less valuable trees than in the primary forest and in stands managed with the selection system.
    Print ISSN: 0015-752X
    Electronic ISSN: 1464-3626
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Published by Oxford University Press
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  • 19
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    The JCMT Plane Survey: early results from the {ell} = 30{degrees} field (2015)
    Moore, T. J. T., Plume, R., Thompson, M. A., Parsons, H., Urquhart, J. S., Eden, D. J., Dempsey, J. T., Morgan, L. K., Thomas, H. S., Buckle, J., Brunt, C. M., Butner, H., Carretero, D., Chrysostomou, A., de; Villiers, H. M., Fich, M., Hoare, M. G., Manser, G., Mottram, J. C., Natario, C., Olguin, F., Peretto, N., Polychroni, D., Redman, R. O., Rigby, A. J., Salji, C., Summers, L. J., Berry, D., Currie, M. J., Jenness, T., Pestalozzi, M., Traficante, A., Bastien, P., di; Francesco, J., Davis, C. J., Evans, A., Friberg, P., Fuller, G. A., Gibb, A. G., Gibson, S., Hill, T., Johnstone, D., Joncas, G., Longmore, S. N., Lumsden, S. L., Martin, P. G., Lu'o'ng, Q. N. t., Pineda, J. E., Purcell, C., Richer, J. S., Schieven, G. H., Shipman, R., Spaans, M., Taylor, A. R., Viti, S., Weferling, B., White, G. J., Zhu, M.
    Oxford University Press
    Details
    Publication Date: 2015-09-19
    Description: We present early results from the JCMT (James Clerk Maxwell Telescope) Plane Survey (JPS), which has surveyed the northern inner Galactic plane between longitudes  = 7° and  = 63° in the 850-μm continuum with SCUBA-2 (Submm Common-User Bolometer Array 2), as part of the JCMT Legacy Survey programme. Data from the  = 30° survey region, which contains the massive-star-forming regions W43 and G29.96, are analysed after approximately 40 per cent of the observations had been completed. The pixel-to-pixel noise is found to be 19 mJy beam –1 after a smooth over the beam area, and the projected equivalent noise levels in the final survey are expected to be around 10 mJy beam –1 . An initial extraction of compact sources was performed using the FellWalker method, resulting in the detection of 1029 sources above a 5 surface-brightness threshold. The completeness limits in these data are estimated to be around 0.2 Jy beam –1 (peak flux density) and 0.8 Jy (integrated flux density) and are therefore probably already dominated by source confusion in this relatively crowded section of the survey. The flux densities of extracted compact sources are consistent with those of matching detections in the shallower APEX (Atacama Pathfinder Experiment) Telescope Large Area Survey of the Galaxy (ATLASGAL) survey. We analyse the virial and evolutionary state of the detected clumps in the W43 star-forming complex and find that they appear younger than the Galactic-plane average.
    Print ISSN: 0035-8711
    Electronic ISSN: 1365-2966
    Topics: Physics
    Published by Oxford University Press
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  • 20
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    Regulation of SPRY3 by X chromosome and PAR2-linked promoters in an autism susceptibility region (2015)
    Oxford University Press
    Details
    Publication Date: 2015-12-01
    Print ISSN: 0964-6906
    Electronic ISSN: 1460-2083
    Topics: Biology , Medicine
    Published by Oxford University Press
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