318 research outputs found

    On geometry of hypersurfaces of a pseudoconformal space of Lorentzian signature

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    There are three types of hypersurfaces in a pseudoconformal space C^n_1 of Lorentzian signature: spacelike, timelike, and lightlike. These three types of hypersurfaces are considered in parallel. Spacelike hypersurfaces are endowed with a proper conformal structure, and timelike hypersurfaces are endowed with a conformal structure of Lorentzian type. Geometry of these two types of hypersurfaces can be studied in a manner that is similar to that for hypersurfaces of a proper conformal space. Lightlike hypersurfaces are endowed with a degenerate conformal structure. This is the reason that their investigation has special features. It is proved that under the Darboux mapping such hypersurfaces are transferred into tangentially degenerate (n-1)-dimensional submanifolds of rank n-2 located on the Darboux hyperquadric. The isotropic congruences of the space C^n_1 that are closely connected with lightlike hypersurfaces and their Darboux mapping are also considered.Comment: LaTeX, 21 page

    Identifying patients' support needs following critical illness:A scoping review of the qualitative literature

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    BACKGROUND: Intensive care survivors suffer chronic and potentially life-changing physical, psychosocial and cognitive sequelae, and supporting recovery is an international priority. As survivors' transition from the intensive care unit to home, their support needs develop and change. METHODS: In this scoping review, we categorised patients' support needs using House's Social Support Needs framework (informational, emotional, instrumental, appraisal) and mapped these against the Timing it Right framework reflecting the patient's transition from intensive care (event/diagnosis) to ward (stabilisation/preparation) and discharge home (implementation/adaptation). We searched electronic databases from 2000 to 2017 for qualitative research studies reporting adult critical care survivors' experiences of care. Two reviewers independently screened, extracted and coded data. Data were analysed using a thematic framework approach. RESULTS: From 3035 references, we included 32 studies involving 702 patients. Studies were conducted in UK and Europe (n = 17, 53%), Canada and the USA (n = 6, 19%), Australasia (n = 6, 19%), Hong Kong (n = 1, 3%), Jordan (n = 1, 3%) and multi-country (n = 1, 3%). Across the recovery trajectory, informational, emotional, instrumental, appraisal and spiritual support needs were evident, and the nature and intensity of need differed when mapped against the Timing it Right framework. Informational needs changed from needing basic facts about admission, to detail about progress and treatments and coping with long-term sequelae. The nature of emotional needs changed from needing to cope with confusion, anxiety and comfort, to a need for security and family presence, coping with flashbacks, and needing counselling and community support. Early instrumental needs ranged from managing sleep, fatigue, pain and needing nursing care and transitioned to needing physical and cognitive ability support, strength training and personal hygiene; and at home, regaining independence, strength and return to work. Appraisal needs related to obtaining feedback on progress, and after discharge, needing reassurance from others who had been through the ICU experience. CONCLUSIONS: This review is the first to identify the change in social support needs among intensive care survivors as they transition from intensive care to the home environment. An understanding of needs at different transition periods would help inform health service provision and support for survivors

    Existence of the Abrikosov vortex state in two-dimensional type-II superconductors without pinning

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    Theory alternative to the vortex lattice melting theories is advertised. The vortex lattice melting theories are science fiction cond-mat/9811051 because the Abrikosov state is not the vortex lattice with crystalline long-range order. Since the fluctuation correction to the Abrikosov solution is infinite in the thermodynamic limit (K.Maki and H.Takayama, 1972) any fluctuation theory of the mixed state should consider a superconductor with finite sizes. Such nonperturbative theory for the easiest case of two-dimensional superconductor in the lowest Landau level approximation is presented in this work. The thermodynamic averages of the spatial average order parameter and of the Abrikosov parameter ÎČa\beta_{a} are calculated. It is shown that the position H_{c4} of the transition into the Abrikosov state (i.e. in the mixed state with long-range phase coherence) depends strongly on sizes of two-dimensional superconductor. Fluctuations eliminate the Abrikosov vortex state in a wide region of the mixed state of thin films with real sizes and without pinning disorders, i.e. H_{c4} << H_{c2}. The latter has experimental corroboration in Phys.Rev.Lett. 75, 2586 (1995).Comment: 4 pages, 0 figure

    The EBV-encoded oncoprotein, LMP1, induces an epithelial-to-mesenchymal transition (EMT) via Its CTAR1 domain through integrin-mediated ERK-MAPK signalling

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    The Epstein⁻Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) oncogene can induce profound effects on epithelial growth and differentiation including many of the features of the epithelial-to-mesenchymal transition (EMT). To better characterise these effects, we used the well-defined Madin Darby Canine Kidney (MDCK) epithelial cell model and found that LMP1 expression in these cells induces EMT as defined by characteristic morphological changes accompanied by loss of E-cadherin, desmosomal cadherin and tight junction protein expression. The induction of the EMT phenotype required a functional CTAR1 domain of LMP1 and studies using pharmacological inhibitors revealed contributions from signalling pathways commonly induced by integrin⁻ligand interactions: extracellular signal-regulated kinases/mitogen-activated protein kinases (ERK-MAPK), PI3-Kinase and tyrosine kinases, but not transforming growth factor beta (TGF&beta;). More detailed analysis implicated the CTAR1-mediated induction of Slug and Twist in LMP1-induced EMT. A key role for &beta;1 integrin signalling in LMP1-mediated ERK-MAPK and focal adhesion kianse (FAK) phosphorylation was observed, and &beta;1 integrin activation was found to enhance LMP1-induced cell viability and survival. These findings support an important role for LMP1 in disease pathogenesis through transcriptional reprogramming that enhances tumour cell survival and leads to a more invasive, metastatic phenotype

    European Multidisciplinary and Water-Column Observatory - European Research Infrastructure Consortium (EMSO ERIC): challenges and opportunities for strategic European marine sciences

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    EMSO (European Multidisciplinary Seafloor and water-column Observatory, www.emso-eu.org) is a large‐scale European Research Infrastructure I. It is a distributed infrastructure of strategically placed, deep‐sea seafloor and water column observatory nodes with the essential scientific objective of real‐time, longterm observation of environmental processes related to the interaction between the geosphere, biosphere, and hydrosphere. The geographic locations of the EMSO observatory nodes represent key sites in European waters, from the Arctic, through the Atlantic and Mediterranean, to the Black Sea (Figure 1), as defined through previous studies performed in FP6 and FP7 EC projects such as ESONET‐CA, ESONET‐NoE, EMSO-PP (Person et al., 2015)Peer Reviewe

    Veterinary drug therapies used for undesirable behaviours in UK dogs under primary veterinary care

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    Undesirable behaviours (UBs) in dogs are common and important issues with serious potential welfare consequences for both the dogs and their owners. This study aimed to investigate the usage of drug therapy for UBs in dogs and assess demographic risk factors for drug-prescribed UBs within the dog population under primary-care veterinary care in the UK in 2013. Dogs receiving drug therapy for UB were identified through the retrospective analysis of anonymised electronic patient records in VetCompassℱ. Risk factor analysis used multivariable logistic regression modelling. The study population comprised 103,597 dogs under veterinary care in the UK during 2013. There were 413 drug-prescribed UBs recorded among 404 dogs. The prevalence of dogs with at least one UB event treated with a drug in 2013 was 0.4%. Multivariable modelling identified 3 breeds with increased odds of drug-prescribed UB compared with crossbred dogs: Toy Poodle (OR 2.75), Tibetan Terrier (OR 2.68) and Shih-tzu (OR 1.95). Increasing age was associated with increased odds of drug-prescribed UB, with dogs ≄ 12 years showing 3.1 times the odds compared with dogs < 3 years. Neutered males (OR 1.82) and entire males (OR 1.50) had increased odds compared with entire females. The relatively low prevalence of dogs with at least one UB event that was treated with a drug in 2013 could suggest that opportunities for useful psychopharmaceutical intervention in UBs may be being missed in first opinion veterinary practice. While bodyweight was not a significant factor, the 3 individual breeds at higher odds of an UB treated with a behaviour modifying drug all have a relatively low average bodyweight. The current results also support previous research of a male predisposition to UBs and it is possible that this higher risk resulted in the increased likelihood of being prescribed a behaviour modifying drug, regardless of neuter status

    Complementary approaches to understanding the plant circadian clock

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    Circadian clocks are oscillatory genetic networks that help organisms adapt to the 24-hour day/night cycle. The clock of the green alga Ostreococcus tauri is the simplest plant clock discovered so far. Its many advantages as an experimental system facilitate the testing of computational predictions. We present a model of the Ostreococcus clock in the stochastic process algebra Bio-PEPA and exploit its mapping to different analysis techniques, such as ordinary differential equations, stochastic simulation algorithms and model-checking. The small number of molecules reported for this system tests the limits of the continuous approximation underlying differential equations. We investigate the difference between continuous-deterministic and discrete-stochastic approaches. Stochastic simulation and model-checking allow us to formulate new hypotheses on the system behaviour, such as the presence of self-sustained oscillations in single cells under constant light conditions. We investigate how to model the timing of dawn and dusk in the context of model-checking, which we use to compute how the probability distributions of key biochemical species change over time. These show that the relative variation in expression level is smallest at the time of peak expression, making peak time an optimal experimental phase marker. Building on these analyses, we use approaches from evolutionary systems biology to investigate how changes in the rate of mRNA degradation impacts the phase of a key protein likely to affect fitness. We explore how robust this circadian clock is towards such potential mutational changes in its underlying biochemistry. Our work shows that multiple approaches lead to a more complete understanding of the clock

    Anthocyanins do not influence long-chain n-3 fatty acid status:Studies in cells, rodents and humans

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    Increased tissue status of the long-chain n-3 polyunsaturated fatty acids (LC n-3 PUFA), eicosapentaenoic (EPA) and docosahexaenoic acid (DHA) is associated with cardiovascular and cognitive benefits. Limited epidemiological and animal data suggest that flavonoids, and specifically anthocyanins, may increase EPA and DHA levels, potentially by increasing their synthesis from the shorter-chain n-3 PUFA, α-linolenic acid. Using complimentary cell, rodent and human studies we investigated the impact of anthocyanins and anthocyanin-rich foods/extracts on plasma and tissue EPA and DHA levels and on the expression of fatty acid desaturase 2 (FADS2), which represents the rate limiting enzymes in EPA and DHA synthesis. In experiment 1, rats were fed a standard diet containing either palm oil or rapeseed oil supplemented with pure anthocyanins for 8 weeks. Retrospective fatty acid analysis was conducted on plasma samples collected from a human randomized controlled trial where participants consumed an elderberry extract for 12 weeks (experiment 2). HepG2 cells were cultured with α-linolenic acid with or without select anthocyanins and their in vivo metabolites for 24 h and 48 h (experiment 3). The fatty acid composition of the cell membranes, plasma and liver tissues were analyzed by gas chromatography. Anthocyanins and anthocyanin-rich food intake had no significant impact on EPA or DHA status or FADS2 gene expression in any model system. These data indicate little impact of dietary anthocyanins on n-3 PUFA distribution and suggest that the increasingly recognized benefits of anthocyanins are unlikely to be the result of a beneficial impact on tissue fatty acid status

    Timelike surfaces of constant mean curvature 1 in anti-de Sitter 3-space

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    It is shown that timelike surfaces of constant mean curvature 1 in anti-de Sitter 3-space can be constructed from a pair of Lorentz holomorphic and Lorentz antiholomorphic null curves in PSL(2,R) via Bryant type representation formulae. These formulae are used to investigate an explicit one-to-one correspondence, the so-called Lawson correspondence, between timelike surfaces of constant mean curvature 1 in anti-de Sitter 3-space and timelike minimal surfaces in Minkowski 3-space. The hyperbolic Gauss map of timelike surfaces in anti-de Sitter 3-space, which is a close analogue of the classical Gauss map is considered. It is discussed that the hyperbolic Gauss map plays an important role in the study of timelike surfaces of constant mean curvature 1 in anti-de Sitter 3-space. In particular, the relationship between the Lorentz holomorphicity of the hyperbolic Gauss map and timelike surfaces of constant mean curvature 1 in anti-de Sitter 3-space is studied.Comment: 47 pages, 24 figures, references revised, Annals of Global Analysis and Geometr

    Observation of the Ankle and Evidence for a High-Energy Break in the Cosmic Ray Spectrum

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    We have measured the cosmic ray spectrum at energies above 101710^{17} eV using the two air fluorescence detectors of the High Resolution Fly's Eye experiment operating in monocular mode. We describe the detector, PMT and atmospheric calibrations, and the analysis techniques for the two detectors. We fit the spectrum to models describing galactic and extragalactic sources. Our measured spectrum gives an observation of a feature known as the ``ankle'' near 3×10183\times 10^{18} eV, and strong evidence for a suppression near 6×10196\times 10^{19} eV.Comment: 14 pages, 9 figures. To appear in Physics Letters B. Accepted versio
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