598 research outputs found
The JCMT dense gas survey of the Perseus Molecular Cloud
We present the results of a large-scale survey of the very dense gas in the
Perseus molecular cloud using HCO+ and HCN (J = 4 - 3) transitions. We have
used this emission to trace the structure and kinematics of gas found in pre-
and protostellar cores, as well as in outflows. We compare the HCO+/HCN data,
highlighting regions where there is a marked discrepancy in the spectra of the
two emission lines. We use the HCO+ to identify positively protostellar
outflows and their driving sources, and present a statistical analysis of the
outflow properties that we derive from this tracer. We find that the relations
we calculate between the HCO+ outflow driving force and the Menv and Lbol of
the driving source are comparable to those obtained from similar outflow
analyses using 12CO, indicating that the two molecules give reliable estimates
of outflow properties. We also compare the HCO+ and the HCN in the outflows,
and find that the HCN traces only the most energetic outflows, the majority of
which are driven by young Class 0 sources. We analyse the abundances of HCN and
HCO+ in the particular case of the IRAS 2A outflows, and find that the HCN is
much more enhanced than the HCO+ in the outflow lobes. We suggest that this is
indicative of shock-enhancement of HCN along the length of the outflow; this
process is not so evident for HCO+, which is largely confined to the outflow
base.Comment: 25 pages, 14 figures, 9 table
Ground-based detection of a cloud of methanol from Enceladus: When is a biomarker not a biomarker?
Saturn's moon Enceladus has vents emerging from a sub-surface ocean, offering
unique probes into the liquid environment. These vents drain into the larger
neutral torus in orbit around Saturn. We present a methanol (CH3OH) detection
observed with IRAM 30-m from 2008 along the line-of-sight through Saturn's
E-ring. Additionally, we also present supporting observations from the Herschel
public archive of water (ortho-H2O; 1669.9 GHz) from 2012 at a similar
elongation and line-of-sight. The CH3OH 5(1,1)-4(1,1) transition was detected
at 5.9 sigma confidence. The line has 0.43 km/s width and is offset by +8.1
km/s in the moon's reference frame. Radiative transfer models allow for gas
cloud dimensions from 1750 km up to the telescope beam diameter ~73000 km.
Taking into account the CH3OH lifetime against solar photodissociation and the
redshifted line velocity, there are two possible explanations for the CH3OH
emission: methanol is primarily a secondary product of chemical interactions
within the neutral torus that (1) spreads outward throughout the E-ring or (2)
originates from a compact, confined gas cloud lagging Enceladus by several
km/s. We find either scenario to be consistent with significant redshifted H2O
emission (4 sigma) measured from the Herschel public archive. The measured
CH3OH:H2O abundance (> 0.5 per cent) significantly exceeds the observed
abundance in the direct vicinity of the vents (~0.01 per cent), suggesting
CH3OH is likely chemically processed within the gas cloud with methane (CH4) as
its parent species.Comment: 16 pages, 4 figures, accepted for publication in the International
Journal of Astrobiology (IJA
The Mink Frog, Rana septentrionalis, in Southeastern Labrador
Mink Frogs (Rana septentrionalis) were collected at three new localities in southeastern Labrador in 2003 and 2005, extending the known range of the species about 200 km to the east, to the limits of the coast.La Grenouille du Nord (Rana septentrionalis) a été trouvée dans trois nouvelles localités dans le sud-est du Labrador en 2003 et 2005. Ces mentions élargissent l’aire de répartition connue de l’espèce d’environ 200 km vers l’est, aux limites de la côte de l’Océan Atlantique
Palomar 5 and its Tidal Tails::A Search for New Members in the Tidal Stream
In this paper we present the results of a search for members of the globular
cluster Palomar 5 and its associated tidal tails. The analysis has been
performed using intermediate and low resolution spectroscopy with the AAOmega
spectrograph on the Anglo-Australian Telescope. Based on kinematics, line
strength and photometric information, we identify 39 new red giant branch stars
along 20 of the tails, a larger angular extent than has been
previously studied. We also recover eight previously known tidal tail members.
Within the cluster, we find seven new red giant and one blue horizontal branch
members and confirm a further twelve known red giant members. In total, we
provide velocity data for 67 stars in the cluster and the tidal tails. Using a
maximum likelihood technique, we derive a radial velocity for Pal 5 of km s and a velocity dispersion of km s. We
confirm and extend the linear velocity gradient along the tails of km s deg, with an associated intrinsic velocity dispersion
of km s. Neither the velocity gradient nor the dispersion
change in any significant way with angular distance from the cluster, although
there is some indication that the gradient may be smaller at greater angular
distances in the trailing tail. Our results verify the tails as kinematically
cold structures and will allow further constraints to be placed on the orbit of
Pal 5, ultimately permitting a greater understanding of the shape and extent of
the Galaxy's dark matter halo.Comment: 14 pages, 9 figures, 4 tables; Accepted for publication in MNRA
Students' social relationships and their links to university transition
• Students can find the transition to higher education difficult (Hussey & Smith, 2010). • Research shows that developing good relationships with peers can help students to integrate into and feel part of university life (Maunder et al, 2010; Pittman & Richmond, 2008). • Feeling isolated, or not making effective social connections, has been found to be important in early withdrawals from university (Wilcox et al, 2005). • We would therefore expect to find a relationship between the quality of students’ relationships with their peers; their self-reported adjustment to university life; and their sense of membership to the university
Intranasal immunisation with recombinant adenovirus vaccines protects against a lethal 2 challenge with pneumonia virus of mice
Pneumonia virus of mice (PVM) infection of BALB/c mice induces bronchiolitis leading to a fatal pneumonia in a dose-dependent manner, closely paralleling the development of severe disease during human respiratory syncytial virus infection in man, and is thus a recognised model in which to study the pathogenesis of pneumoviruses. This model system was used to investigate delivery of the internal structural proteins of PVM as a potential vaccination strategy to protect against pneumovirus disease. Replication-deficient recombinant human adenovirus serotype 5 (rAd5) vectors were constructed that expressed the M or N gene of PVM pathogenic strain J3666. Intranasal delivery of these rAd5 vectors gave protection against a lethal challenge dose of PVM in three different mouse strains, and protection lasted for at least 20 weeks post-immunisation. Whilst the PVM-specific antibody response isuch animals was weak and inconsistent, rAd5N primed a strong PVM-specific CD8+ T cell response and, to a lesser extent, a CD4+ T cell response. These findings suggest that protection induced by rAd5N was mediated by T-cells rather than serum antibody
Twisted topological structures related to M-branes
Studying the M-branes leads us naturally to new structures that we call
Membrane-, Membrane^c-, String^K(Z,3)- and Fivebrane^K(Z,4)-structures, which
we show can also have twisted counterparts. We study some of their basic
properties, highlight analogies with structures associated with lower levels of
the Whitehead tower of the orthogonal group, and demonstrate the relations to
M-branes.Comment: 17 pages, title changed on referee's request, minor changes to
improve presentation, typos correcte
The James Clerk Maxwell telescope dense gas survey of the Perseus molecular cloud
This is the final version of the article. Available from the publisher via the DOI in this record.We present the results of a large-scale survey of the very dense (n > 106 cm-3) gas in the Perseus molecular cloud using HCO+ and HCN (J = 4 → 3) transitions. We have used this emission to trace the structure and kinematics of gas found in pre- and protostellar cores, as well as in outflows. We compare the HCO+/HCN data, highlighting regions where there is a marked discrepancy in the spectra of the two emission lines. We use the HCO+ to identify positively protostellar outflows and their driving sources, and present a statistical analysis of the outflow properties that we derive from this tracer. We find that the relations we calculate between the HCO+ outflow driving force and the Menv and Lbol of the driving source are comparable to those obtained from similar outflow analyses using 12CO, indicating that the two molecules give reliable estimates of outflow properties. We also compare the HCO+ and the HCN in the outflows, and find that the HCN traces only the most energetic outflows, the majority of which are driven by young Class 0 sources. We analyse the abundances of HCN and HCO+ in the particular case of the IRAS 2A outflows, and find that the HCN is much more enhanced than the HCO+ in the outflow lobes. We suggest that this is indicative of shock enhancement of HCN along the length of the outflow; this process is not so evident for HCO+, which is largely confined to the outflow base. © 2014 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.SLW-S and JH are funded by the Science and Technology Facilities
Council of the UK. The James Clerk Maxwell Telescope is
operated by the Joint Astronomy Centre on behalf of the Science
and Technology Facilities Council of the United Kingdom, the National
Research Council of Canada and (until 2013 March 31) the
Netherlands Organisation for Scientific Researc
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