11,748 research outputs found
VLTI observations of the dust geometry around R Coronae Borealis stars
We are investigating the formation and evolution of dust around the
hydrogen-deficient supergiants known as R Coronae Borealis (RCB) stars. We aim
to determine the connection between the probable merger past of these stars and
their current dust-production activities. We carried out high-angular
resolution interferometric observations of three RCB stars, namely RY Sgr, V
CrA, and V854 Cen with the mid-IR interferometer, MIDI on the VLTI, using two
telescope pairs. The baselines ranged from 30 to 60 m, allowing us to probe the
dusty environment at very small spatial scales (~ 50 mas or 400 stellar radii).
The observations of the RCB star dust environments were interpreted using both
geometrical models and one-dimensional radiative transfer codes. From our
analysis we find that asymmetric circumstellar material is apparent in RY Sgr,
may also exist in V CrA, and is possible for V854 Cen. Overall, we find that
our observations are consistent with dust forming in clumps ejected randomly
around the RCB star so that over time they create a spherically symmetric
distribution of dust. However, we conclude that the determination of whether
there is a preferred plane of dust ejection must wait until a time series of
observations are obtained.Comment: Accepted for publication in MNRAS; 14 pages, 10 figures, 6 table
The eVALuate study: two parallel randomised trials, one comparing laparoscopic with abdominal hysterectomy, the other comparing laparoscopic with vaginal hysterectomy
OBJECTIVE: To compare the effects of laparoscopic hysterectomy
and abdominal hysterectomy in the abdominal trial, and
laparoscopic hysterectomy and vaginal hysterectomy in the
vaginal trial.
DESIGN: Two parallel, multicentre, randomised trials.
Setting 28 UK centres and two South African centres.
Participants 1380 women were recruited; 1346 had surgery;
937 were followed up at one year.
PRIMARY OUTCOME: outcome Rate of major complications.
RESULTS: In the abdominal trial laparoscopic hysterectomy was
associated with a higher rate of major complications than
abdominal hysterectomy (11.1% v 6.2%, P = 0.02; difference
4.9%, 95% confidence interval 0.9% to 9.1%) and the number
needed to treat to harm was 20. Laparoscopic hysterectomy
also took longer to perform (84 minutes v 50 minutes) but was
less painful (visual analogue scale 3.51 v 3.88, P = 0.01) and
resulted in a shorter stay in hospital after the operation (3 days
v 4 days). Six weeks after the operation, laparoscopic
hysterectomy was associated with less pain and better quality of
life than abdominal hysterectomy (SF-12, body image scale, and
sexual activity questionnaires).
In the vaginal trial we found no evidence of a difference in
major complication rates between laparoscopic hysterectomy
and vaginal hysterectomy (9.8% v 9.5%, P = 0.92; difference
0.3%, − 5.2% to 5.8%), and the number needed to treat to harm
was 333.We found no evidence of other differences between
laparoscopic hysterectomy and vaginal hysterectomy except
that laparoscopic hysterectomy took longer to perform (72
minutes v 39 minutes) and was associated with a higher rate of
detecting unexpected pathology (16.4% v 4.8%, P = < 0.01).
However, this trial was underpowered.
CONCLUSIONS: Laparoscopic hysterectomy was associated with a
significantly higher rate of major complications than abdominal
hysterectomy. It also took longer to perform but was associated
with less pain, quicker recovery, and better short term quality of
life. The trial comparing vaginal hysterectomy with laparoscopic
hysterectomy was underpowered and is inconclusive on the rate
of major complications; however, vaginal hysterectomy took less
time
Avian Models for Human Cognitive Neuroscience: A Proposal.
Research on avian cognitive neuroscience over the past two decades has revealed the avian brain to be a better model for understanding human cognition than previously thought, despite differences in the neuroarchitecture of avian and mammalian brains. The brain, behavior, and cognition of songbirds have provided an excellent model of human cognition in one domain, namely learning human language and the production of speech. There are other important behavioral candidates of avian cognition, however, notably the capacity of corvids to remember the past and plan for the future, as well as their ability to think about another's perspective, and physical reasoning. We review this work and assess the evidence that the corvid brain can support such a cognitive architecture. We propose potential applications of these behavioral paradigms for cognitive neuroscience, including recent work on single-cell recordings and neuroimaging in corvids. Finally, we discuss their impact on understanding human developmental cognition.Biotechnology and Biological Sciences Research CouncilThis is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.neuron.2015.04.02
Do birds have the capacity for fun?
A crow carries a jar lid to the top of a sloping snowy rooftop in Russia. Sitting on the lid and sliding down the roof, you could think of it as surfing. It picks up the lid and repeats this behaviour again and again (Figure 1A). A group of black swans ride the crest of a wave that also looks like they are surfing. Once the wave reaches the beach, the swans fly back to another wave crest and perform the same actions again (Figure 1B). In both cases, the birds’ behaviours do not seem to provide any obvious function apart from enjoyment — they look like they are having fun. Videos of these behaviours received millions of views on YouTube, so we appear to like watching other animals having fun. But is this interpretation of the birds’ actions as having fun pure anthropomorphism or is it possible that an animal can act solely for its own enjoyment?This is the author accepted manuscript. The final version is available from Elsevier via http://dx.doi.org/10.1016/j.cub.2014.09.02
DNET: A communications facility for distributed heterogeneous computing
This document describes DNET, a heterogeneous data communications networking facility. DNET allows programs operating on hosts on dissimilar networks to communicate with one another without concern for computer hardware, network protocol, or operating system differences. The overall DNET network is defined as the collection of host machines/networks on which the DNET software is operating. Each underlying network is considered a DNET 'domain'. Data communications service is provided between any two processes on any two hosts on any of the networks (domains) that may be reached via DNET. DNET provides protocol transparent, reliable, streaming data transmission between hosts (restricted, initially to DECnet and TCP/IP networks). DNET also provides variable length datagram service with optional return receipts
Spin-1 Particles with Light-Front Approach
For the vector sector, i.e, mesons with spin-1, the electromagnetic form
factors and anothers observables are calculated with the light-front approach.
However, the light-front quantum field theory have some problems, for example,
the rotational symmetry breaking. We solve that problem added the zero modes
contribuition to the matrix elements of the electromagnetic current, besides
the valence contribuition. We found that among the four independent matrix
elements of the plus component in the light-front helicity basis only the one carries zero mode contributions.Comment: 5 pages. 3 Figures, use latex and EPJ styl
Living with hate relationships: familiar encounters, enduring racisms and geographies of entrapment
This paper utilises the concept of ‘hate relationships’ in conversation with the literature on geographies of encounter to explore experiences of racism for those entrapped by racist encounters with those who are familiar. In so doing we attend to the uneven and harmful risks involved in some forms of everyday urban encounter. We draw upon case notes collated by a hate advocacy service in North East England, UK, to illustrate the cumulative damaging force of enduring hate relationships. By drawing parallels with work on domestic violence, we suggest hate relationships evident in our data exhibit distinct temporalities of routinisation, whereby harmful ‘low level’ violence, often under the radar of the criminal justice system, gains force through repeated neighbourhood-based encounters. In so doing we also highlight both the situated and relational spatialities at work; localised encounters marked by familiarity, racialised territoriality and experiences of fear and immobility, but also relations of entrenched disadvantage and institutional failures that sustain harm. Concerted acts of resistance look to confront and/or escape these relationships, but as forms of resolution, where additional burdens are placed on victim/survivors, these are constrained by the same violent conditions through which such relationships are allowed to take shape
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