2,538 research outputs found
ALMA observations of TiO around VY Canis Majoris
Titanium dioxide, TiO, is a refractory species that could play a crucial
role in the dust-condensation sequence around oxygen-rich evolved stars. To
date, gas phase TiO has been detected only in the complex environment of
the red supergiant VY CMa. We aim to constrain the distribution and excitation
of TiO around VY CMa in order to clarify its role in dust formation. We
analyse spectra and channel maps for TiO extracted from ALMA science
verification data. We detect 15 transitions of TiO, and spatially resolve
the emission for the first time. The maps demonstrate a highly clumpy,
anisotropic outflow in which the TiO emission likely traces gas exposed to
the stellar radiation field. A roughly east-west oriented, accelerating
bipolar-like structure is found, of which the blue component runs into and
breaks up around a solid continuum component. A distinct tail to the south-west
is seen for some transitions, consistent with features seen in the optical and
near-infrared. We find that a significant fraction of TiO remains in the
gas phase outside the dust-formation zone and suggest that this species might
play only a minor role in the dust-condensation process around extreme
oxygen-rich evolved stars like VY CMa.Comment: Accepted for publication in Astronomy & Astrophysics, 25 pages, 20
figure
Risk factors for hospital admission with RSV bronchiolitis in England: a population-based birth cohort study.
OBJECTIVE: To examine the timing and duration of RSV bronchiolitis hospital admission among term and preterm infants in England and to identify risk factors for bronchiolitis admission.
DESIGN: A population-based birth cohort with follow-up to age 1 year, using the Hospital Episode Statistics database. SETTING: 71 hospitals across England.
PARTICIPANTS: We identified 296618 individual birth records from 2007/08 and linked to subsequent hospital admission records during the first year of life.
RESULTS: In our cohort there were 7189 hospital admissions with a diagnosis of bronchiolitis, 24.2 admissions per 1000 infants under 1 year (95%CI 23.7-24.8), of which 15% (1050/7189) were born preterm (47.3 bronchiolitis admissions per 1000 preterm infants (95% CI 44.4-50.2)). The peak age group for bronchiolitis admissions was infants aged 1 month and the median was age 120 days (IQR = 61-209 days). The median length of stay was 1 day (IQR = 0-3). The relative risk (RR) of a bronchiolitis admission was higher among infants with known risk factors for severe RSV infection, including those born preterm (RR = 1.9, 95% CI 1.8-2.0) compared with infants born at term. Other conditions also significantly increased risk of bronchiolitis admission, including Down's syndrome (RR = 2.5, 95% CI 1.7-3.7) and cerebral palsy (RR = 2.4, 95% CI 1.5-4.0).
CONCLUSIONS: Most (85%) of the infants who are admitted to hospital with bronchiolitis in England are born at term, with no known predisposing risk factors for severe RSV infection, although risk of admission is higher in known risk groups. The early age of bronchiolitis admissions has important implications for the potential impact and timing of future active and passive immunisations. More research is needed to explain why babies born with Down's syndrome and cerebral palsy are also at higher risk of hospital admission with RSV bronchiolitis
ALMA sub-mm maser and dust distribution of VY Canis Majoris
Cool, evolved stars have copious, enriched winds. The structure of these
winds and the way they are accelerated is not well known. We need to improve
our understanding by studying the dynamics from the pulsating stellar surface
to about 10 stellar radii, where radiation pressure on dust is fully effective.
Some red supergiants have highly asymmetric nebulae, implicating additional
forces. We retrieved ALMA Science Verification data providing images of sub-mm
line and continuum emission from VY CMa. This enables us to locate water masers
with milli-arcsec precision and resolve the dusty continuum. The 658-, 321- and
325-GHz masers lie in irregular, thick shells at increasing distances from the
centre of expansion. For the first time this is confirmed as the stellar
position, coinciding with a compact peak offset to the NW of the brightest
continuum emission. The maser shells (and dust formation zone) overlap but
avoid each other on tens-au scales. Their distribution is broadly consistent
with excitation models but the conditions and kinematics appear to be
complicated by wind collisions, clumping and asymmetries.Comment: Letter 4 pages, 5 figures plus appendix with 3 figures. Accepted by
Astronomy and Astrophysics Letter
Phenoloxidase activity acts as a mosquito innate immune response against infection with semliki forest virus
Several components of the mosquito immune system including the RNA interference (RNAi), JAK/STAT, Toll and IMD pathways have previously been implicated in controlling arbovirus infections. In contrast, the role of the phenoloxidase (PO) cascade in mosquito antiviral immunity is unknown. Here we show that conditioned medium from the Aedes albopictus-derived U4.4 cell line contains a functional PO cascade, which is activated by the bacterium Escherichia coli and the arbovirus Semliki Forest virus (SFV) (Togaviridae; Alphavirus). Production of recombinant SFV expressing the PO cascade inhibitor Egf1.0 blocked PO activity in U4.4 cell- conditioned medium, which resulted in enhanced spread of SFV. Infection of adult female Aedes aegypti by feeding mosquitoes a bloodmeal containing Egf1.0-expressing SFV increased virus replication and mosquito mortality. Collectively, these results suggest the PO cascade of mosquitoes plays an important role in immune defence against arboviruses
Small-scale solar magnetic fields
As we resolve ever smaller structures in the solar atmosphere, it has become
clear that magnetism is an important component of those small structures.
Small-scale magnetism holds the key to many poorly understood facets of solar
magnetism on all scales, such as the existence of a local dynamo, chromospheric
heating, and flux emergence, to name a few. Here, we review our knowledge of
small-scale photospheric fields, with particular emphasis on quiet-sun field,
and discuss the implications of several results obtained recently using new
instruments, as well as future prospects in this field of research.Comment: 43 pages, 18 figure
Atomic diffraction from nanostructured optical potentials
We develop a versatile theoretical approach to the study of cold-atom
diffractive scattering from light-field gratings by combining calculations of
the optical near-field, generated by evanescent waves close to the surface of
periodic nanostructured arrays, together with advanced atom wavepacket
propagation on this optical potential.Comment: 8 figures, 10 pages, submitted to Phys. Rev.
A multi-centre, randomised controlled trial of cognitive therapy to prevent harmful compliance with command hallucinations
<p>Abstract</p> <p>Background</p> <p>Command hallucinations are among the most distressing, high risk and treatment resistant symptoms for people with psychosis; however, currently, there are no evidence-based treatment options available for this group. A cognitive therapy grounded in the principles of the Social Rank Theory, is being evaluated in terms of its effectiveness in reducing harmful compliance with command hallucinations.</p> <p>Methods/Design</p> <p>This is a single blind, intention-to-treat, multi-centre, randomized controlled trial comparing Cognitive Therapy for Command Hallucinations + Treatment as Usual with Treatment as Usual alone. Eligible participants have to fulfil the following inclusion criteria: i) ≥16 years; ii) ICD-10 diagnosis of schizophrenia or related disorder; iii) command hallucinations for at least 6 months leading to risk of harm to self or others. Following the completion of baseline assessments, eligible participants will be randomly allocated to either the Cognitive Therapy for Command Hallucinations + Treatment as Usual group or the Treatment as Usual group. Outcome will be assessed at 9 and 18 months post randomization with assessors blind to treatment allocation. The primary outcome is compliance behaviour and secondary outcomes include beliefs about voices' power, distress, psychotic symptoms together with a health economic evaluation. Qualitative interviews with services users will explore the acceptability of Cognitive Therapy for Command Hallucinations.</p> <p>Discussion</p> <p>Cognitive behaviour therapy is recommended for people with psychosis; however, its focus and evaluation has primarily revolved around the reduction of psychotic symptoms. In this trial, however, the focus of the cognitive behavioural intervention is on individuals' appraisals, behaviour and affect and not necessarily symptoms; this is also reflected in the outcome measures used. If successful, the results will mark a significant breakthrough in the evidence base for service users and clinicians and will provide a treatment option for this group where none currently exist. The trial will open the way for further breakthrough work with the 'high risk' population of individuals with psychosis, which we would intend to pursue.</p> <p>Trial registration</p> <p>ISRCTN: <a href="http://www.controlled-trials.com/ISRCTN62304114">ISRCTN62304114</a></p
Multi-Jet Event Rates in Deep Inelastic Scattering and Determination of the Strong Coupling Constant
Jet event rates in deep inelastic ep scattering at HERA are investigated
applying the modified JADE jet algorithm. The analysis uses data taken with the
H1 detector in 1994 and 1995. The data are corrected for detector and
hadronization effects and then compared with perturbative QCD predictions using
next-to-leading order calculations. The strong coupling constant alpha_S(M_Z^2)
is determined evaluating the jet event rates. Values of alpha_S(Q^2) are
extracted in four different bins of the negative squared momentum
transfer~\qq in the range from 40 GeV2 to 4000 GeV2. A combined fit of the
renormalization group equation to these several alpha_S(Q^2) values results in
alpha_S(M_Z^2) = 0.117+-0.003(stat)+0.009-0.013(syst)+0.006(jet algorithm).Comment: 17 pages, 4 figures, 3 tables, this version to appear in Eur. Phys.
J.; it replaces first posted hep-ex/9807019 which had incorrect figure 4
Multiplicity Structure of the Hadronic Final State in Diffractive Deep-Inelastic Scattering at HERA
The multiplicity structure of the hadronic system X produced in
deep-inelastic processes at HERA of the type ep -> eXY, where Y is a hadronic
system with mass M_Y< 1.6 GeV and where the squared momentum transfer at the pY
vertex, t, is limited to |t|<1 GeV^2, is studied as a function of the invariant
mass M_X of the system X. Results are presented on multiplicity distributions
and multiplicity moments, rapidity spectra and forward-backward correlations in
the centre-of-mass system of X. The data are compared to results in e+e-
annihilation, fixed-target lepton-nucleon collisions, hadro-produced
diffractive final states and to non-diffractive hadron-hadron collisions. The
comparison suggests a production mechanism of virtual photon dissociation which
involves a mixture of partonic states and a significant gluon content. The data
are well described by a model, based on a QCD-Regge analysis of the diffractive
structure function, which assumes a large hard gluonic component of the
colourless exchange at low Q^2. A model with soft colour interactions is also
successful.Comment: 22 pages, 4 figures, submitted to Eur. Phys. J., error in first
submission - omitted bibliograph
- …