1,273 research outputs found
Electromagnetic Chirps from Neutron Star-Black Hole Mergers
We calculate the electromagnetic signal of a gamma-ray flare coming from the
surface of a neutron star shortly before merger with a black hole companion.
Using a new version of the Monte Carlo radiation transport code Pandurata that
incorporates dynamic spacetimes, we integrate photon geodesics from the neutron
star surface until they reach a distant observer or are captured by the black
hole. The gamma-ray light curve is modulated by a number of relativistic
effects, including Doppler beaming and gravitational lensing. Because the
photons originate from the inspiraling neutron star, the light curve closely
resembles the corresponding gravitational waveform: a chirp signal
characterized by a steadily increasing frequency and amplitude. We propose to
search for these electromagnetic chirps using matched filtering algorithms
similar to those used in LIGO data analysis.Comment: 13 pages, 5 figures, submitted to Ap
'It's not one size fits all':A qualitative study of patients' and healthcare professionals' views of self-management for bronchiectasis
Background Bronchiectasis is a chronic respiratory condition that impacts significantly on individuals and healthcare services. Self-management is recommended in clinical guidelines for bronchiectasis as an intervention to enable patients to manage their condition, yet there is little evidence to support it.Methods Three face to face focus groups (17 adults with bronchiectasis) were conducted at three National Health Service (NHS) sites in North West England. Additionally, semi-structured telephone interviews were undertaken with 11 healthcare professionals (HCPs), including doctors, nurses and physiotherapists. Thematic analysis identified common themes and occurrences verified by independent audit.Findings Four common overarching themes were identified: the meaning of self-management; benefits; barriers and influencers to self-management; subthemes varied. Both groups recognised component interventions. Patients highlighted that self-management enabled them to learn what works and moderate behaviour. Aspects of delivery and structure were important to HCPs but a ‘make do’ culture was evident. Benefits for both groups included empowering patients. Common barriers for patients were time, mood and lack of access to support which could mitigate engagement with self-management. HCPs identified barriers including patient characteristics and lack of resources. Influencers for patients were peer, carer and psychosocial support, for HCPs influencers were individual patient attributes, including ability and motivation, and HCP characteristics such as knowledge and understanding about bronchiectasis.Summary This is the first study to explore patients’ and HCPs’ views of self-management for bronchiectasis. The need for an individual, flexible and responsive self-management programme specific to bronchiectasis was evident. Personal characteristics of patients and HCPs could affect the uptake and engagement with self-management and HCPs knowledge of the disease is a recognised precursor to effective self-management. The study identified key aspects for consideration during development, delivery and sustainability of self-management programmes and findings suggest that patients’ psychosocial and socioeconomic circumstances may affect adoption and activation of self-management behaviours
Surface grafting of electrospun fibers using ATRP and RAFT for the control of biointerfacial interactions
BACKGROUND The ability to present signalling molecules within a low fouling 3D environment that mimics the extracellular matrix is an important goal for a range of biomedical applications, both in vitro and in vivo. Cell responses can be triggered by non-specific protein interactions occurring on the surface of a biomaterial, which is an undesirable process when studying specific receptor-ligand interactions. It is therefore useful to present specific ligands of interest to cell surface receptors in a 3D environment that minimizes non-specific interactions with biomolecules, such as proteins. METHOD In this study, surface-initiated atom transfer radical polymerization (SI-ATRP) of poly(ethylene glycol)-based monomers was carried out from the surface of electrospun fibers composed of a styrene/vinylbenzyl chloride copolymer. Surface initiated radical addition-fragmentation chain transfer (SI-RAFT) polymerisation was also carried out to generate bottle brush copolymer coatings consisting of poly(acrylic acid) and poly(acrylamide). These were grown from surface trithiocarbonate groups generated from the chloromethyl styrene moieties existing in the original synthesised polymer. XPS was used to characterise the surface composition of the fibers after grafting and after coupling with fluorine functional XPS labels. RESULTS Bottle brush type coatings were able to be produced by ATRP which consisted of poly(ethylene glycol) methacrylate and a terminal alkyne-functionalised monomer. The ATRP coatings showed reduced non-specific protein adsorption, as a result of effective PEG incorporation and pendant alkynes groups existing as part of the brushes allowed for further conjugation of via azide-alkyne Huisgen 1,3-dipolar cycloaddition. In the case of RAFT, carboxylic acid moieties were effectively coupled to an amine label via amide bond formation. In each case XPS analysis demonstrated that covalent immobilisation had effectively taken place. CONCLUSION Overall, the studies presented an effective platform for the preparation of 3D scaffolds which contain effective conjugation sites for attachment of specific bioactive signals of interest, as well as actively reducing non-specific protein interactions.This research was supported by the Cooperative Research Centre for
Polymers (CRCP)
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Graft versus Host Disease in the Bone Marrow, Liver and Thymus Humanized Mouse Model
Mice bearing a “humanized” immune system are valuable tools to experimentally manipulate human cells in vivo and facilitate disease models not normally possible in laboratory animals. Here we describe a form of GVHD that develops in NOD/SCID mice reconstituted with human fetal bone marrow, liver and thymus (NS BLT mice). The skin, lungs, gastrointestinal tract and parotid glands are affected with progressive inflammation and sclerosis. Although all mice showed involvement of at least one organ site, the incidence of overt clinical disease was approximately 35% by 22 weeks after reconstitution. The use of hosts lacking the IL2 common gamma chain (NOD/SCID/γc−/−) delayed the onset of disease, but ultimately did not affect incidence. Genetic analysis revealed that particular donor HLA class I alleles influenced the risk for the development of GVHD. At a cellular level, GVHD is associated with the infiltration of human CD4+ T cells into the skin and a shift towards Th1 cytokine production. GVHD also induced a mixed M1/M2 polarization phenotype in a dermal murine CD11b+, MHC class II+ macrophage population. The presence of xenogenic GVHD in BLT mice both presents a major obstacle in the use of humanized mice and an opportunity to conduct preclinical studies on GVHD in a humanized model
Modelling and operational management of the Dawson Pit 6-8 lowwall instability
A case study of a deep-seated spoil lowwall instability controlled by a classical active- passive wedge mechanism at Anglo American Metallurgical Coal’s Dawson Mine is presented. Following a truck dump extension, widespread displacements were identified during conventional single forward pass de-coaling of Pit 6-8 strip E15. New through-spoil drilling, downhole geophysical logging, and XRD analysis identified a moisture-sensitive tuffaceous claystone unit containing a high proportion of medium-high swelling, mixed-layer illite-smectite clays 11-12 m below the lowwall floor. A novel soil mechanics approach was used to determine the mechanical properties of the tuffaceous claystone for which conventional rock mechanics tests could not be applied. Three-dimensional numerical modelling was then undertaken in FLAC3D to: a) validate the characterised mechanical properties; b) determine appropriate buttress slot widths for retreat mining of strip E16; and c) provide a validated base case for the predictive modelling and design of future strips. Operational controls for mining of strip E16 included: surface monitoring (radar, LiDAR); subsurface monitoring (TDR, VWPs); and an adaptive mine plan following the Observational Method. The TDR confirmed that the tuffaceous claystone unit at 11-12 m depth was acting as the sole basal horizon controlling the instability and mining of strip E16 was completed safely without coal sterilisation
Spin-transfer torque induced reversal in magnetic domains
Using the complex stereographic variable representation for the macrospin,
from a study of the nonlinear dynamics underlying the generalized
Landau-Lifshitz(LL) equation with Gilbert damping, we show that the
spin-transfer torque is effectively equivalent to an applied magnetic field. We
study the macrospin switching on a Stoner particle due to spin-transfer torque
on application of a spin polarized current. We find that the switching due to
spin-transfer torque is a more effective alternative to switching by an applied
external field in the presence of damping. We demonstrate numerically that a
spin-polarized current in the form of a short pulse can be effectively employed
to achieve the desired macro-spin switching.Comment: 16 pages, 6 figure
Computer modeling in training Bachelor of Electromechanics
У публікації наведені дисципліни у яких відбувається цілеспрямоване формування навичок моделювання бакалаврів електромеханіки, розглянуті компетенції, які ці дисципліни охоплюють. Визначено, що блок моделювання забезпечує теоретичне та практичне наповнення фундаментальної, загально та спеціалізовано-професійної підготовки бакалавра електромеханіки, надаючи можливість сформувати компетентність бакалавра електромеханіки в моделюванні.The publication given discipline which is focused Bachelor modeling the skills eleсtromechanics, reviewed competencies that these disciplines cover. Determined that the simulation unit provides theoretical and practical content of basic, general and specialized professional training Bachelor Electromechanics, providing the ability to create competence Bachelor of Electromechanics in simulation
Gut microbiota induce IGF-1 and promote bone formation and growth
New interventions are needed to improve bone health and reduce the risk for osteoporosis and fracture. Dysbiosis is increasingly linked to metabolic abnormalities, although the effect of the microbiota on skeletal health is poorly understood. Previous studies suggest microbiota are detrimental to bone by increasing resorption. In this report, we show that the gut resident microbiota promote bone formation, as well as resorption, with long-term exposure to microbiota resulting in net skeletal growth. Microbiota induce the hormone insulin-like growth factor 1 (IGF-1), which promotes bone growth and remodeling. Short-chain fatty acids (SCFAs), produced when microbiota ferment fiber, also induce IGF-1, suggesting a mechanism by which microbiota affect bone health. Manipulating the microbiome or its metabolites may afford opportunities to optimize bone health and growth
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