975 research outputs found
Interface Contributions to Topological Entanglement in Abelian Chern-Simons Theory
We study the entanglement entropy between (possibly distinct) topological
phases across an interface using an Abelian Chern-Simons description with
topological boundary conditions (TBCs) at the interface. From a microscopic
point of view, these TBCs correspond to turning on particular gapping
interactions between the edge modes across the interface. However, in studying
entanglement in the continuum Chern-Simons description, we must confront the
problem of non-factorization of the Hilbert space, which is a standard property
of gauge theories. We carefully define the entanglement entropy by using an
extended Hilbert space construction directly in the continuum theory. We show
how a given TBC isolates a corresponding gauge invariant state in the extended
Hilbert space, and hence compute the resulting entanglement entropy. We find
that the sub-leading correction to the area law remains universal, but depends
on the choice of topological boundary conditions. This agrees with the
microscopic calculation of \cite{Cano:2014pya}. Additionally, we provide a
replica path integral calculation for the entropy. In the case when the
topological phases across the interface are taken to be identical, our
construction gives a novel explanation of the equivalence between the
left-right entanglement of (1+1)d Ishibashi states and the spatial entanglement
of (2+1)d topological phases.Comment: 36 pages, 7 figures, two appendice
Nonlinear physics of the ionosphere and LOIS/LOFAR
The ionosphere is the only large-scale plasma laboratory without walls that
we have direct access to. From results obtained in systematic, repeatable
experiments in this natural laboratory, where we can vary the stimulus and
observe its response in a controlled, repeatable manner, we can draw
conclusions on similar physical processes occurring naturally in the Earth's
plasma environment as well as in parts of the plasma universe that are not
easily accessible to direct probing.
Of particular interest is electromagnetic turbulence excited in the
ionosphere by beams of particles (photons, electrons) and its manifestation in
terms of secondary radiation (electrostatic and electromagnetic waves),
structure formation (solitons, cavitons, alfveons, striations), and the
associated exchange of energy, linear momentum, and angular momentum.
We present a new diagnostic technique, based on vector radio allowing the
utilization of EM angular momentum (vorticity), to study plasma turbulence
remotely.Comment: Six pages, two figures. To appear in Plasma Physics and Controlled
Fusio
Hygiene in the home: relating bugs and behaviour.
Much infectious intestinal disease (IID) arises in the home environment. If programmes to prevent infection are to be effective it is essential to both identify the particular practices that risk disease transmission, and to understand the reasons for these practices. An in-depth, multidisciplinary study of carer and child hygiene in the domestic environment in the Wirral, UK, employed structured observation, surface swabbing for polio vaccine virus and enteric marker organisms, semi-structured interviews, projective interviews and focus group discussions. Observations revealed that child carers washed hands with soap after changing a dirty nappy on 42% of occasions, and that one in five toilet users did not wash hands with soap afterwards. Microbiological samples were taken from household surfaces at sites thought likely to be involved in the transfer of faecal material. 15% of bathroom samples showed contamination with polio vaccine virus. Nappy changing took place mainly in living rooms. Contact with living room surfaces and objects during nappy changing was frequent and evidence of faecal contamination was found in 12% of living room samples. Evidence of faecal contamination was also found in kitchens, again on surfaces thought likely to be involved in the transmission of faeces (taps and soap dispensers). Key factors motivating hygiene were the desire to give a good impression to others, protection of the child and aesthetics. In this setting, the particular risk practices to be addressed included washing hands with soap after stool and nappy contact and preventing the transfer of pathogenic organisms to the kitchen. The occasion of the birth of a child may be a privileged moment for the promotion of safer home hygiene practices. Using polio vaccine virus as an indicator of faecal contamination produces results that could be used in large-scale studies of household disease transmission. A better understanding of the household transmission of the agents of IID using multidisciplinary methods is needed if effective hygiene promotion programmes are to be designed
A standardised sampling protocol for robust assessment of reach-scale fish community diversity in wadeable New Zealand streams
The New Zealand fish fauna contains species that are affected not only by river system connectivity, but also by catchment and local-scale changes in landcover, water quality and habitat quality. Consequently, native fish have potential as multi-scale bioindicators of human pressure on stream ecosystems, yet no standardised, repeatable and scientifically defensible methods currently exist for effectively quantifying their abundance or diversity in New Zealand stream reaches. Here we report on the testing of a back-pack electrofishing method, modified from that used by the United States Environmental Protection Agency, on a wide variety of wadeable stream reaches throughout New Zealand. Seventy-three first- to third-order stream reaches were fished with a single pass over 150-345 m length. Time taken to sample a reach using single-pass electrofishing ranged from 1-8 h. Species accumulation curves indicated that, irrespective of location, continuous sampling of 150 stream metres is required to accurately describe reach-scale fish species richness using this approach. Additional species detection beyond 150 m was rare (<10%) with a single additional species detected at only two out of the 17 reaches sampled beyond this distance. A positive relationship was also evident between species detection and area fished, although stream length rather than area appeared to be the better predictor. The method tested provides a standardised and repeatable approach for regional and/or national reporting on the state of New Zealand's freshwater fish communities and trends in richness and abundance over time
Association between resting heart rate across the life course and all-cause mortality: longitudinal findings from the Medical Research Council (MRC) National Survey of Health and Development (NSHD)
Background: Resting heart rate (RHR) is an independent risk factor for mortality. Nevertheless, it is unclear whether elevations in childhood and mid-adulthood RHR, including changes over time, are associated with mortality later in life. We sought to evaluate the association between RHR across the life course, along with its changes and all-cause mortality. /
Methods: We studied 4638 men and women from the Medical Research Council (MRC) National Survey of Health and Development (NSHD) cohort born during 1 week in 1946. RHR was obtained during childhood at ages 6, 7 and 11, and in mid-adulthood at ages 36 and 43. Using multivariable Cox regression, we calculated the HR for incident mortality according to RHR measured at each time point, along with changes in mid-adulthood RHR. /
Results: At age 11, those in the top fifth of the RHR distribution (≥97 bpm) had an increased adjusted hazard of 1.42 (95% CI 1.04 to 1.93) for all-cause mortality. A higher adjusted risk (HR, 95% CI 2.17, 1.40 to 3.36) of death was also observed for those in the highest fifth (≥81 bpm) at age 43. For a >25 bpm increased change in the RHR over the course of 7 years (age 36–43), the adjusted hazard was elevated more than threefold (HR, 95% CI 3.26, 1.54 to 6.90). After adjustment, RHR at ages 6, 7 and 36 were not associated with all-cause mortality. /
Conclusions: Elevated RHR during childhood and midlife, along with greater changes in mid-adulthood RHR, are associated with an increased risk of all-cause mortality
Big data challenges in overcoming China’s water and air pollution: relevant data and indicators
Big data are potentially useful for environmental management planning and actions that can be directed toward pollu-tion control. China is using big data approaches to help reduce its current levels of pollution. However, also needed are better environmental indicators, measurement technologies, data management and reporting, and adaptive manage-ment and enforcement. Based on continental-extent monitoring and assessment programs in Europe and the USA, we recommend three major programmatic changes for China. (1) Establish long-term systemic environmental and human health objectives and indicators. (2) Adopt national standard methods for survey designs, sampling and analytical pro-tocols, statistical analyses, and collaborative sampling programs. (3) Provide a transparent process for reporting and correcting data errors
In situ observations of microscale damage evolution in unidirectional natural fibre composites
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Variations in arterial pedal circulation in idiopathic congenital talipes equinovarus: a systematic review.
Variations in pedal circulation in congenital talipes equinovarus (CTEV) are well documented. There is a reported risk of vascular injury to the posterior tibial artery (PTA) during operative procedures for CTEV, potentially leading to necrosis and amputation. The aim of this systematic review was to identify the most common anomalies in arterial pedal circulation in CTEV and to determine the relevance of these to clinical practice. The systematic review was registered on PROSPERO and was carried out according to Preferred Reporting Items for Systematic Reviews and Meta Analyses guidelines by two independent reviewers. Studies that examined pedal circulation in idiopathic CTEV were included. Articles that studied nonidiopathic CTEV and those not published in English were excluded. Data extracted included patient demographics, imaging modalities, and findings. A total of 14 articles satisfied the inclusion criteria, including 192 patients (279 clubfeet), aged 0-13.5 years, at various stages in their treatment. Imaging modalities included arteriography (n = 5), duplex ultrasound (n = 5), magnetic resonance angiography (n = 2), and direct visualization intraoperatively (n = 2). The dorsalis pedis was most frequently reported as absent (21.5%), and the anterior tibial artery (ATA) was most frequently reported as hypoplastic (18.3%). Where reported (n = 36 feet), 61% of patients were noted to have a dominant supply from the PTA. The most common variation in pedal circulation in CTEV is diminished supply from ATA and dorsalis pedis, although there are documented anomalies in all of the vessels supplying the foot. We therefore recommend routine Doppler ultrasound imaging prior to operative intervention in CTEV
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