3,541 research outputs found
Partial synchronisation of stochastic oscillators through hydrodynamic coupling
Holographic optical tweezers are used to construct a static bistable optical
potential energy landscape where a Brownian particle experiences restoring
forces from two nearby optical traps and undergoes thermally activated
transitions between the two energy minima. Hydrodynamic coupling between two
such systems results in their partial synchronisation. This is interpreted as
an emergence of higher mobility pathways, along which it is easier to overcome
barriers to structural rearrangement.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
Decapods as food, companions and research animals: Legal impact of ascribing sentience
This commentary provides an overview of the practical implications of attributing sentience to protect decapods as food, companion and research animals in the UK context. Recognising their capacity to suffer has implications for humane slaughter in farming and fishing sectors. It should also place a greater duty of care on owners of captive decapods, considering their needs and avoiding unnecessary suffering. The recognition of decapod sentience should also have an impact on their protection as research animals, although research with a potential to cause suffering may be needed to better understand decapodsâ capacity to suffer
Resolving the Surfaces of Extrasolar Planets With Secondary Eclipse Light Curves
We present a method that employs the secondary eclipse light curves of
transiting extrasolar planets to probe the spatial variation of their thermal
emission. This technique permits an observer to resolve the surface of the
planet without the need to spatially resolve its central star. We evaluate the
feasibility of this technique for the HD 209458 system [..]. We consider two
representations of the planetary thermal emission; a simple model parameterized
by a sinusoidal dependence on longitude and latitude, as well as the results of
a three-dimensional dynamical simulation of the planetary atmosphere previously
published by Cooper & Showman. We find that observations of the secondary
eclipse light curve are most sensitive to a longitudinal offset in the
geometric and photometric centroids of the hemisphere of the planet visible
near opposition. To quantify this signal, we define a new parameter, the
``uniform time offset,'' which measures the time lag between the observed
secondary eclipse and that predicted by a planet with a uniform surface flux
distribution. We compare the predicted amplitude of this parameter for HD
209458 with the precision with which it could be measured with IRAC. We find
that IRAC observations at 3.6um a single secondary eclipse should permit
sufficient precision to confirm or reject the Cooper & Showman model of the
surface flux distribution for this planet. We quantify the signal-to-noise
ratio for this offset in the remaining IRAC bands (4.5um, 5.8um, and 8.0um),
and find that a modest improvement in photometric precision (as might be
realized through observations of several eclipse events) should permit a
similarly robust detection.Comment: AASTeX 5.2, 24 pages, 5 figures, accepted for publication in ApJ; v2:
clarifications, updated to version accepted by ApJ; v3: try to reduce spacin
Optical tweezers: wideband microrheology
Microrheology is a branch of rheology having the same principles as
conventional bulk rheology, but working on micron length scales and micro-litre
volumes.
Optical tweezers have been successfully used with Newtonian fluids for
rheological purposes such as determining fluid viscosity. Conversely, when
optical tweezers are used to measure the viscoelastic properties of complex
fluids the results are either limited to the material's high-frequency
response, discarding important information related to the low-frequency
behavior, or they are supplemented by low-frequency measurements performed with
different techniques, often without presenting an overlapping region of clear
agreement between the sets of results. We present a simple experimental
procedure to perform microrheological measurements over the widest frequency
range possible with optical tweezers. A generalised Langevin equation is used
to relate the frequency-dependent moduli of the complex fluid to the
time-dependent trajectory of a probe particle as it flips between two optical
traps that alternately switch on and off.Comment: 13 pages, 6 figures, submitted to Special Issue of the Journal of
Optic
Clinical effectiveness and cost-effectiveness of open and arthroscopic rotator cuff repair [the UK Rotator Cuff Surgery (UKUFF) randomised trial]
Peer reviewedPublisher PD
Sizing of High-Aspect-Ratio Wings with Folding Wingtips
High-aspect-ratio wings are of particular interest to modern aircraft design due to the inherent reduction in induced drag that they provide. However, such wing configurations often come with problems such as increased structural weight and oversized wingspans for existing airport facilities. Unlike conventional folding wingtips, as used on the 777-X, this paper demonstrates the use of semi-aeroelastic hinge devices that enable aircraft incorporating high-aspect-ratio wings not only to fit into airport gates, but also to alleviate aerodynamic loads by allowing floating wingtips to be used in-flight. This study establishes a preliminary design process for such a wing configuration and undertakes a comprehensive sizing process to investigate the impact of the device on wing weight and aircraft performance. For the cases considered, a reduction in wing weight of approximately 25% can be achieved by utilizing the semi-aeroelastic hinge, which can lead to more than 5% improvement in aircraft range
Preventing and lessening exacerbations of asthma in school-age children associated with a new term (PLEASANT) : Study protocol for a cluster randomised control trial
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly citedBackground: Within the UK, during September, there is a pronounced increase in the number of unscheduled medical contacts by school-aged children (4-16 years) with asthma. It is thought that that this might be caused by the return back to school after the summer holidays, suddenly mixing with other children again and picking up viruses which could affect their asthma. There is also a drop in the number of prescriptions administered in August. It is possible therefore that children might not be taking their medication as they should during the summer contributing to them becoming ill when they return to school. It is hoped that a simple intervention from the GP to parents of children with asthma at the start of the summer holiday period, highlighting the importance of maintaining asthma medication can help prevent increased asthma exacerbation, and unscheduled NHS appointments, following return to school in September.Methods/design: PLEASANT is a cluster randomised trial. A total of 140 General Practices (GPs) will be recruited into the trial; 70 GPs randomised to the intervention and 70 control practices of "usual care" An average practice is expected to have approximately 100 children (aged 4-16 with a diagnosis of asthma) hence observational data will be collected on around 14000 children over a 24-month period. The Clinical Practice Research Datalink will collect all data required for the study which includes diagnostic, prescription and referral data.Discussion: The trial will assess whether the intervention can reduce exacerbation of asthma and unscheduled medical contacts in school-aged children associated with the return to school after the summer holidays. It has the potential to benefit the health and quality of life of children with asthma while also improving the effectiveness of NHS services by reducing NHS use in one of the busiest months of the year. An exploratory health economic analysis will gauge any cost saving associated with the intervention and subsequent impacts on quality of life. If results for the intervention are positive it is hoped that this could be adopted as part of routine care management of childhood asthma in general practice. Trial registration: Current controlled trials: ISRCTN03000938 (assigned 19/10/12) http://www.controlled-trials.com/ISRCTN03000938/.UKCRN ID: 13572.Peer reviewe
Frustrations of fur-farmed mink
Captive animals may suffer if strongly motivated to perform activities that their housing does not allow. We investigated this experimentally for caged mink, and found that they would pay high costs to perform a range of natural behaviours, and release cortisol if their most preferred activity, swimming, was prevented.
Investigates the effect of limitations on caged mink. Popularity of fur farming; Research into the possible deprivation of mink, which result in their frustration; Details of the experiment; Impact of an access to water; Results which indicate that fur-farmed mink are still motivated to perform the same activities as their wild counterpart
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