728 research outputs found

    A Robust Navigation Technique for Integration in the Guidance and Control of an Uninhabited Surface Vehicle

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    In this paper, we propose a novel robust navigational approach to be integrated with the guidance and control systems of an uninhabitedsurface vehicle Springer. A weighted Interval Kalman Filter (wIKF) in used for waypoint tracking, and has been compared with that of one that uses a conventional Kalman Filter (KF) navigational design. The conventional KF fails to predict correctly the vehicle’s heading when there is unmodelled uncertainty of the sensing equipment, and thus would negatively affect the performance of subsequent navigation, guidance and control (NGC). While the proposed method using a wIKF technique enhances robustness with respect to erroneous modelling, and thus secures better accuracy and efficiency in completing a mission

    Understanding new models of integrated care in developed countries: a systematic review

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    Background The NHS has been challenged to adopt new integrated models of service delivery that are tailored to local populations. Evidence from the international literature is needed to support the development and implementation of these new models of care. Objectives The study aimed to carry out a systematic review of international evidence to enhance understanding of the mechanisms whereby new models of service delivery have an impact on health-care outcomes. Design The study combined rigorous and systematic methods for identification of literature, together with innovative methods for synthesis and presentation of findings. Setting Any setting. Participants Patients receiving a health-care service and/or staff delivering services. Interventions Changes to service delivery that increase integration and co-ordination of health and health-related services. Main outcome measures Outcomes related to the delivery of services, including the views and perceptions of patients/service users and staff. Study design Empirical work of a quantitative or qualitative design. Data sources We searched electronic databases (between October 2016 and March 2017) for research published from 2006 onwards in databases including MEDLINE, EMBASE, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, Science Citation Index, Social Science Citation Index and The Cochrane Library. We also searched relevant websites, screened reference lists and citation searched on a previous review. Review methods The identified evidence was synthesised in three ways. First, data from included studies were used to develop an evidence-based logic model, and a narrative summary reports the elements of the pathway. Second, we examined the strength of evidence underpinning reported outcomes and impacts using a comparative four-item rating system. Third, we developed an applicability framework to further scrutinise and characterise the evidence. Results We included 267 studies in the review. The findings detail the complex pathway from new models to impacts, with evidence regarding elements of new models of integrated care, targets for change, process change, influencing factors, service-level outcomes and system-wide impacts. A number of positive outcomes were reported in the literature, with stronger evidence of perceived increased patient satisfaction and improved quality of care and access to care. There was stronger UK-only evidence of reduced outpatient appointments and waiting times. Evidence was inconsistent regarding other outcomes and system-wide impacts such as levels of activity and costs. There was an indication that new models have particular potential with patients who have complex needs. Limitations Defining new models of integrated care is challenging, and there is the potential that our study excluded potentially relevant literature. The review was extensive, with diverse study populations and interventions that precluded the statistical summary of effectiveness. Conclusions There is stronger evidence that new models of integrated care may enhance patient satisfaction and perceived quality and increase access; however, the evidence regarding other outcomes is unclear. The study recommends factors to be considered during the implementation of new models. Future work Links between elements of new models and outcomes require further study, together with research in a wider variety of populations. Study registration This study is registered as PROSPERO CRD37725. Funding The National Institute for Health Research Health Services and Delivery Research programme

    Field inter-comparison of eleven atmospheric ammonia measurement techniques

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    Eleven instruments for the measurement of ambient concentrations of atmospheric ammonia gas (NH3), based on eight different measurement methods were inter-compared above an intensively managed agricultural field in late summer 2008 in Southern Scotland. To test the instruments over a wide range of concentrations, the field was fertilised with urea midway through the experiment, leading to an increase in the average concentration from 10 to 100 ppbv. The instruments deployed included three wet-chemistry systems, one with offline analysis (annular rotating batch denuder, RBD) and two with online-analysis (Annular Denuder sampling with online Analysis, AMANDA; AiRRmonia), two Quantum Cascade Laser Absorption Spectrometers (a large-cell dual system; DUAL-QCLAS, and a compact system; c-QCLAS), two photo-acoustic spectrometers (WaSul-Flux; Nitrolux-100), a Cavity Ring Down Spectrosmeter (CRDS), a Chemical Ionisation Mass Spectrometer (CIMS), an ion mobility spectrometer (IMS) and an Open-Path Fourier Transform Infra-Red (OP-FTIR) Spectrometer. The instruments were compared with each other and with the average concentration of all instruments. An overall good agreement of hourly average concentrations between the instruments (R2>0.84), was observed for NH3 concentrations at the field of up to 120 ppbv with the slopes against the average ranging from 0.67 (DUAL-QCLAS) to 1.13 (AiRRmonia) with intercepts of −0.74 ppbv (RBD) to +2.69 ppbv (CIMS). More variability was found for performance for lower concentrations (<10 ppbv). Here the main factors affecting measurement precision are (a) the inlet design, (b) the state of inlet filters (where applicable), and (c) the quality of gas-phase standards (where applicable). By reference to the fast (1 Hz) instruments deployed during the study, it was possible to characterize the response times of the slower instruments

    Star Formation and Dynamics in the Galactic Centre

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    The centre of our Galaxy is one of the most studied and yet enigmatic places in the Universe. At a distance of about 8 kpc from our Sun, the Galactic centre (GC) is the ideal environment to study the extreme processes that take place in the vicinity of a supermassive black hole (SMBH). Despite the hostile environment, several tens of early-type stars populate the central parsec of our Galaxy. A fraction of them lie in a thin ring with mild eccentricity and inner radius ~0.04 pc, while the S-stars, i.e. the ~30 stars closest to the SMBH (<0.04 pc), have randomly oriented and highly eccentric orbits. The formation of such early-type stars has been a puzzle for a long time: molecular clouds should be tidally disrupted by the SMBH before they can fragment into stars. We review the main scenarios proposed to explain the formation and the dynamical evolution of the early-type stars in the GC. In particular, we discuss the most popular in situ scenarios (accretion disc fragmentation and molecular cloud disruption) and migration scenarios (star cluster inspiral and Hills mechanism). We focus on the most pressing challenges that must be faced to shed light on the process of star formation in the vicinity of a SMBH.Comment: 68 pages, 35 figures; invited review chapter, to be published in expanded form in Haardt, F., Gorini, V., Moschella, U. and Treves, A., 'Astrophysical Black Holes'. Lecture Notes in Physics. Springer 201

    Measurement of (anti)deuteron and (anti)proton production in DIS at HERA

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    The first observation of (anti)deuterons in deep inelastic scattering at HERA has been made with the ZEUS detector at a centre-of-mass energy of 300--318 GeV using an integrated luminosity of 120 pb-1. The measurement was performed in the central rapidity region for transverse momentum per unit of mass in the range 0.3<p_T/M<0.7. The particle rates have been extracted and interpreted in terms of the coalescence model. The (anti)deuteron production yield is smaller than the (anti)proton yield by approximately three orders of magnitude, consistent with the world measurements.Comment: 26 pages, 9 figures, 5 tables, submitted to Nucl. Phys.

    Low Q^2 Jet Production at HERA and Virtual Photon Structure

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    The transition between photoproduction and deep-inelastic scattering is investigated in jet production at the HERA ep collider, using data collected by the H1 experiment. Measurements of the differential inclusive jet cross-sections dsigep/dEt* and dsigmep/deta*, where Et* and eta* are the transverse energy and the pseudorapidity of the jets in the virtual photon-proton centre of mass frame, are presented for 0 < Q2 < 49 GeV2 and 0.3 < y < 0.6. The interpretation of the results in terms of the structure of the virtual photon is discussed. The data are best described by QCD calculations which include a partonic structure of the virtual photon that evolves with Q2.Comment: 20 pages, 5 Figure

    Hadron Production in Diffractive Deep-Inelastic Scattering

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    Characteristics of hadron production in diffractive deep-inelastic positron-proton scattering are studied using data collected in 1994 by the H1 experiment at HERA. The following distributions are measured in the centre-of-mass frame of the photon dissociation system: the hadronic energy flow, the Feynman-x (x_F) variable for charged particles, the squared transverse momentum of charged particles (p_T^{*2}), and the mean p_T^{*2} as a function of x_F. These distributions are compared with results in the gamma^* p centre-of-mass frame from inclusive deep-inelastic scattering in the fixed-target experiment EMC, and also with the predictions of several Monte Carlo calculations. The data are consistent with a picture in which the partonic structure of the diffractive exchange is dominated at low Q^2 by hard gluons.Comment: 16 pages, 6 figures, submitted to Phys. Lett.

    Energy Flow in the Hadronic Final State of Diffractive and Non-Diffractive Deep-Inelastic Scattering at HERA

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    An investigation of the hadronic final state in diffractive and non--diffractive deep--inelastic electron--proton scattering at HERA is presented, where diffractive data are selected experimentally by demanding a large gap in pseudo --rapidity around the proton remnant direction. The transverse energy flow in the hadronic final state is evaluated using a set of estimators which quantify topological properties. Using available Monte Carlo QCD calculations, it is demonstrated that the final state in diffractive DIS exhibits the features expected if the interaction is interpreted as the scattering of an electron off a current quark with associated effects of perturbative QCD. A model in which deep--inelastic diffraction is taken to be the exchange of a pomeron with partonic structure is found to reproduce the measurements well. Models for deep--inelastic epep scattering, in which a sizeable diffractive contribution is present because of non--perturbative effects in the production of the hadronic final state, reproduce the general tendencies of the data but in all give a worse description.Comment: 22 pages, latex, 6 Figures appended as uuencoded fil

    A Search for Selectrons and Squarks at HERA

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    Data from electron-proton collisions at a center-of-mass energy of 300 GeV are used for a search for selectrons and squarks within the framework of the minimal supersymmetric model. The decays of selectrons and squarks into the lightest supersymmetric particle lead to final states with an electron and hadrons accompanied by large missing energy and transverse momentum. No signal is found and new bounds on the existence of these particles are derived. At 95% confidence level the excluded region extends to 65 GeV for selectron and squark masses, and to 40 GeV for the mass of the lightest supersymmetric particle.Comment: 13 pages, latex, 6 Figure
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