127 research outputs found
Evaluating the potential impacts of grey seal predation and fishery bycatch/discards on cod productivity on the Western Scotian Shelf and in the Bay of Fundy
The recovery of many groundfish stocks throughout the Northwest Atlantic has
been impeded by elevated natural (i.e., non-fishing) mortality (M) among
older/larger individuals. The causes of elevated mortality are not well known,
though predation by rapidly growing grey seal herds and unreported fishing are
thought to be possible drivers of mortality for Atlantic Cod (Gadus morhua) on
the Western Scotian Shelf and in the Bay of Fundy (known as "4X5Y cod") and in
nearby ecosystems. We developed a statistical catch-at-age model for 4X5Y cod
that accounted for both grey seal predation and estimated bycatch/discards to
evaluate the degree to which either of these factors may influence cod
mortality. The model was fit over a range of predation and discarding scenarios
to account for uncertainties and a lack of data for these processes. We found
that most cod M remained unaccounted for unless cod comprised a large
proportion (>0.45) of the grey seal diet by weight. If the reported bycatch
estimates are taken as accurate, then the magnitude of cod discards from
non-directed fisheries was minor, though these estimates are highly uncertain.Comment: 27 pages, 4 tables, 10 figures, 2 appendice
Young stars and reflection nebulae near the lower "edge" of the Galactic molecular disc
We investigate the star formation occurring in a region well below the
Galactic plane towards the optical reflection nebula ESO 368-8 (IRAS
07383-3325). We confirm the presence of a small young stellar cluster (or
aggregate of tens of YSOs) identified earlier, embedded in a molecular cloud
located near the lower "edge" of the Galactic disc, and characterise the young
stellar population. We report the discovery of a near-infrared nebula, and
present a CO map revealing a new dense, dynamic cloud core. We used
near-infrared JHKs images, millimetre CO spectra and optical V-band images.
This star formation region displays an optical reflection nebula (ESO 368-8)
and a near-infrared nebula located about 46" (1.1 pc) from each other. The two
nebulae are likely to be coeval and to represent two manifestations of the same
single star formation episode with about 1 Myr age. The near-IR nebula reveals
an embedded, optically and near-IR invisible source whose light scatters off a
cavity carved by previous stellar jets or molecular outflows and into our
line-of-sight. The molecular cloud is fully covered by our CO(J=1-0) maps and,
traced by this line, extends over a region of 7.8 x 7.8 pc^2, exhibiting an
angular size 5.4' x 5.4' and shape (close to circular) similar to spherical (or
slightly cometary) globules. Towards the direction of the near-IR nebula, the
molecular cloud contains a dense core where the molecular gas exhibits large
line widths indicative of a very dynamical state, with stirred gas and
supersonic motions. Our estimates of the mass of the molecular gas in this
region range from 600 to 1600 solar masses. The extinction Av towards the
positions of the optical reflection nebula and of the near-IR nebula was found
to be Av=3-4 mag and Av=12-15 mag, respectively.Comment: 11 pages, 13 figure
BMD-based assessment of local porosity in human femoral cortical bone
Cortical pores are determinants of the elastic properties and of the ultimate strength of bone tissue. An increase of the overall cortical porosity (Ct.Po) as well as the local coalescence of large pores cause an impairment of the mechanical competence of bone Therefore, Ct Po represents a relevant target for identifying patients with high fracture risk. However, given their small size, the in vivo imaging of cortical pores remains challenging. The advent of modern high-resolution peripheral quantitative computed tomography (HR-pQCT) triggered new methods for the clinical assessment of Ct Po at the peripheral skeleton, either by pore segmentation or by exploiting local bone mineral density (BMD) In this work, we compared BMD-based Ct.Po estimates with highresolution reference values measured by scanning acoustic microscopy. A calibration rule to estimate local Ct.Po from BMD as assessed by HR-pQCT was derived experimentally. Within areas of interest smaller than 0.5 mm(2), our model was able to estimate the local Ct.Po with an error of 3.4%. The incorporation of the BMD mhomogeneity and of one parameter from the BMD distribution of the entire scan volume led to a relative reduction of the estimate error of 30%, if compared to an estimate based on the average BMD. When applied to the assessment of Ct.Po within entire cortical bone cross-sections, the proposed BMD-based method had better accuracy than measurements performed with a conventional threshold-based approach.</p
Long-term functional outcome of distal radius fractures is associated with early post-fracture bone stiffness of the fracture region:An HR-pQCT exploratory study
\u3cp\u3eIdentifying determinants of long-term functional outcome after a distal radius fracture is challenging. Previously, we reported on the association between early HR-pQCT measurements and clinical outcome 12 weeks after a conservatively treated distal radius fracture. We extended the follow-up and assessed functional outcome after two years in relation to early HR-pQCT derived bone parameters. HR-pQCT scans of the fracture region were performed in 15 postmenopausal women with a distal radius fracture at 1-2 (baseline), 3-4 weeks and 26 months post-fracture. Additionally, the contralateral distal radius was scanned at baseline. Bone density, micro-architecture parameters and bone stiffness using micro-finite element analysis (μFEA) were evaluated. During all visits, wrist pain and function were assessed using the patient-rated wrist evaluation questionnaire (PRWE), quantifying functional outcome with a score between 0 and 100. Two-year PRWE was associated with torsional and bending stiffness 3-4 weeks post-fracture (R2: 0.49, p = 0.006 and R2: 0.54, p = 0.003, respectively). In contrast, early micro-architecture parameters of the fracture region or contralateral bone parameters did not show any association with long-term outcome. This exploratory study indicates that HR-pQCT with μFEA performed within four weeks after a distal radius fracture captures biomechanical fracture characteristics that are associated with long-term functional outcome and therefore could be a valuable early outcome measure in clinical trials and clinical practice.\u3c/p\u3
Does police size matter?:A review of the evidence regarding restructuring police organisations
Restructuring and merging public sector organisations is often seen as a way to enhance efficiency and efficacy. There is ongoing debate about the impact of police force sizes, structures and mergers as police organisations attempt to adapt to reductions in their budgets and changes in patterns of criminality. The article reviews the evidence regarding key aspects of police reform: finding mixed evidence regarding the links between size and performance, while noting risks that mergers may impair local policing. The article discusses the impact of mergers on protective services, governance and accountability, while also discussing potential risks and opportunities associated with the merger process itself. The review finds significant gaps in the available evidence, and significant opportunities to expand the evidence base on this topic. Given current gaps in the evidence regarding size, efficacy and efficiency, it is important to give due consideration to symbolic and rhetorical aspects of mergers
Correction: Large cortical bone pores in the tibia are associated with proximal femur strength
[This corrects the article DOI: 10.1371/journal.pone.0215405.
A Uniform CO Survey of the Molecular Clouds in Orion and Monoceros
We report the results of a new large scale survey of the Orion-Monoceros
complex of molecular clouds made in the J = 1->0 line of CO with the
Harvard-Smithsonian 1.2m millimetre-wave telescope. The survey consists of
52,288 uniformly spaced spectra that cover an area of 432 square degrees on the
sky and is the most sensitive large-scale survey of the region to date.
Distances to the constituent molecular clouds of the complex, estimated from an
analysis of foreground and background stars, have provided information on the
three dimensional structure of the entire complex.Comment: Accepted for publication in Astronomy and Astrophysics. 19 pages with
17 colour figures - 39 if you count the sub-figures separately. The figures
here have been bit-mapped with some loss of quality and beauty. The paper
version in A&A will be in greyscale with the on-line version in colour. In
the meantime the colour version can be obtained by following links at
http://www.star.bris.ac.uk/mrwm . The 9MB PostScript is recommended if you
have appropriate bandwidth or otherwise the 2.3MB PDF is usabl
Grain growth signatures in the protoplanetary discs of Chamaeleon and Lupus
We present ATCA results of a 3 and 7 mm continuum survey of 20 T Tauri stars
in the Chamaeleon and Lupus star forming regions. This survey aims to identify
protoplanetary discs with signs of grain growth. We detected 90% of the sources
at 3 and 7 mm, and determined the spectral slopes, dust opacity indices and
dust disc masses. We also present temporal monitoring results of a small
sub-set of sources at 7, 15 mm and 3+6 cm to investigate grain growth to cm
sizes and constrain emission mechanisms in these sources. Additionally, we
investigated the potential correlation between grain growth signatures in the
infrared (10 \mu m silicate feature) and millimetre (1-3 mm spectral slope,
{\alpha}). Eleven sources at 3 and 7 mm have dominant thermal dust emission up
to 7 mm, with 7 of these having a 1-3 mm dust opacity index less than unity,
suggesting grain growth up to at least mm sizes. The Chamaeleon sources
observed at 15 mm and beyond show the presence of excess emission from an
ionised wind and/or chromo- spheric emission. Long-timescale monitoring at 7 mm
indicated that cm-sized pebbles are present in at least four sources.
Short-timescale monitoring at 15 mm suggests the excess emission is from
thermal free-free emission. Finally, a weak correlation was found between the
strength of the 10 \mum feature and {\alpha}, suggesting simultaneous dust
evolution of the inner and outer parts of the disc. This survey shows that
grain growth up to cm-sized pebbles and the presence of excess emission at 15
mm and beyond are common in these systems, and that temporal monitoring is
required to disentangle these emission mechanisms.Comment: 31 pages, 13 figures, 11 tables, accepted for publication in MNRA
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