10,126 research outputs found

    Human behavioural analysis with self-organizing map for ambient assisted living

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    This paper presents a system for automatically classifying the resting location of a moving object in an indoor environment. The system uses an unsupervised neural network (Self Organising Feature Map) fully implemented on a low-cost, low-power automated home-based surveillance system, capable of monitoring activity level of elders living alone independently. The proposed system runs on an embedded platform with a specialised ceiling-mounted video sensor for intelligent activity monitoring. The system has the ability to learn resting locations, to measure overall activity levels and to detect specific events such as potential falls. First order motion information, including first order moving average smoothing, is generated from the 2D image coordinates (trajectories). A novel edge-based object detection algorithm capable of running at a reasonable speed on the embedded platform has been developed. The classification is dynamic and achieved in real-time. The dynamic classifier is achieved using a SOFM and a probabilistic model. Experimental results show less than 20% classification error, showing the robustness of our approach over others in literature with minimal power consumption. The head location of the subject is also estimated by a novel approach capable of running on any resource limited platform with power constraints

    Free-free and H42alpha emission from the dusty starburst within NGC 4945 as observed by ALMA

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    We present observations of the 85.69 GHz continuum emission and H42alpha line emission from the central 30 arcsec within NGC 4945. Both sources of emission originate from nearly identical structures that can be modelled as exponential discs with a scale length of ~2.1 arcsec (or ~40 pc). An analysis of the spectral energy distribution based on combining these data with archival data imply that 84% +/- 10% of the 85.69 GHz continuum emission originates from free-free emission. The electron temperature is 5400 +/- 600 K, which is comparable to what has been measured near the centre of the Milky Way Galaxy. The star formation rate (SFR) based on the H42alpha and 85.69 GHz free-free emission (and using a distance of 3.8 Mpc) is 4.35 +/- 0.25 M/yr. This is consistent with the SFR from the total infrared flux and with previous measurements based on recombination line emission, and it is within a factor of ~2 of SFRs derived from radio data. The Spitzer Space Telescope 24 micron data and Wide-field Infrared Survey Explorer 22 micron data yield SFRs ~10x lower than the ALMA measurements, most likely because the mid-infrared data are strongly affected by dust attenuation equivalent to A_V=150. These results indicate that SFRs based on mid-infrared emission may be highly inaccurate for dusty, compact circumnuclear starbursts.Comment: 19 pages, 9 figures, accepted for publication in MNRA

    Virtual Site as an aid to first-year learning

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    Courses run by the School of the Built Environment have a range of entry requirements that enable diverse students and those with lower academic qualifications to gain entry. This results in a particular challenge for the Documentation & Estimating module, which is a very practical, skillsand competence-based module. It is delivered to large tutorial cohorts of mixed courses, abilities, ages and experience. Many students need one-toone guidance to understand what, practically, they have to do. They are given the theory first in a lecture and then have practical tutorials to carry out assessed exercises with limited tutor contact time. The module includes some basic surveying techniques and a levelling exercise which involves the transfer of a level from an assumed benchmark to establish a temporary benchmark some distance away. Many students have problems with computation of results. In spite of a careful introduction and explanation of the use of the instruments and techniques, many students find it difficult to visualise what is happening

    Using the local gyrokinetic code, GS2, to investigate global ITG modes in tokamaks. (I) s-α{\alpha} model with profile and flow shear effects

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    This paper combines results from a local gyrokinetic code with analytical theory to reconstruct the global eigenmode structure of the linearly unstable ion-temperature-gradient (ITG) mode with adiabatic electrons. The simulations presented here employ the s-α{\alpha} tokamak equilibrium model. Local gyrokinetic calculations, using GS2 have been performed over a range of radial surfaces, x, and for ballooning phase angle, p, in the range -π≤p≤π{\pi} {\leq} p {\leq\pi}, to map out the complex local mode frequency, Ω0(x,p)=ω0(x,p)+iγ0(x,p){\Omega_0(x, p) = \omega_0(x, p) + i\gamma_0(x, p)}. Assuming a quadratic radial profile for the drive, namely ηi=Ln/LT{\eta_i = L_n/L_T}, (holding constant all other equilibrium profiles such as safety factor, magnetic shear etc.), Ω0(x,p){\Omega_0(x, p)} has a stationary point. The reconstructed global mode then sits on the outboard mid plane of the tokamak plasma, and is known as a conventional or isolated mode, with global growth rate, γ{\gamma} ~ Max[γ0(x,p){\gamma_0(x, p)}], where γ0(x,p){\gamma_0(x, p)} is the local growth rate. Taking the radial variation in other equilibrium profiles (e.g safety factor q(x)) into account, removes the stationary point in Ω0(x,p){\Omega_0(x, p)} and results in a mode that peaks slightly away from the outboard mid-plane with a reduced global growth rate. Finally, the influence of flow shear has also been investigated through a Doppler shift, ω0→ω0+nΩ′x{\omega_0 \rightarrow \omega_0 + n\Omega^{\prime}x}, where n is the toroidal mode number and Ω′{\Omega^{\prime}} incorporates the effect of flow shear. The equilibrium profile variation introduces an asymmetry to the growth rate spectrum with respect to the sign of Ω′{\Omega^{\prime}}, consistent with recent global gyrokinetic calculations.Comment: 10 pages, 8 figures and 1 tabl

    Public Involvement in research within care homes: Benefits and challenges in the APPROACH Study

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    Public involvement in research (PIR) can improve research design and recruitment. Less is known about how PIR enhances the experience of participation and enriches the data collection process. In a study to evaluate how UK care homes and primary health care services achieve integrated working to promote older people’s health, PIR was integrated throughout the research processes. Objectives This paper aims to present one way in which PIR has been integrated into the design and delivery of a multi-site research study based in care homes. Design A prospective case study design, with an embedded qualitative evaluation of PIR activity. Setting and Participants Data collection was undertaken in six care homes in three sites in England. Six PIR members participated: all had prior personal or work experience in care homes. Data Collection Qualitative data collection involved discussion groups, and site-specific meetings to review experiences of participation, benefits and challenges, and completion of structured fieldwork notes after each care home visit. Results PIR members supported: recruitment, resident and staff interviews and participated in data interpretation. Benefits of PIR work were resident engagement that minimised distress and made best use of limited research resources. Challenges concerned communication and scheduling. Researcher support for PIR involvement was resource intensive. Discussion and Conclusions Clearly defined roles with identified training and support facilitated involvement in different aspectsPublic Involvement in Research members of the research team: Gail Capstick, Marion Cowie, Derek Hope, Rita Hewitt, Alex Mendoza, John Willmott. Also the involvement of Steven Iliffe and Heather Gag

    Contextual Modulation of Mirror and Countermirror Sensorimotor Associations

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    Automatic imitation – the unintended copying of observed actions - is thought to be a behavioural product of the mirror neuron system (MNS). Evidence that the MNS develops through associative learning comes from previous research showing that automatic imitation is attenuated by counter-mirror training, in which the observation of one action is paired contingently with the execution of a different action. If the associative account of the MNS is correct, counter-mirror training should show context-specificity, because countermirror associations render action stimuli ambiguous, and ambiguity promotes contextual control. Two experiments are reported which confirm this prediction. In Experiment 1 we found less residual automatic imitation when human participants were tested in their counter-mirror training context. In Experiment 2, sensorimotor training where participants made action responses to novel abstract stimuli was insensitive to the same context manipulation, confirming that the former result was not a procedural artefact. Contextual modulation may enable the MNS to function effectively in spite of the fact that action observation often excites multiple conflicting MNS responses

    Kinetic instabilities that limit {\beta} in the edge of a tokamak plasma: a picture of an H-mode pedestal

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    Plasma equilibria reconstructed from the Mega-Amp Spherical Tokamak (MAST) have sufficient resolution to capture plasma evolution during the short period between edge-localized modes (ELMs). Immediately after the ELM steep gradients in pressure, P, and density, ne, form pedestals close to the separatrix, and they then expand into the core. Local gyrokinetic analysis over the ELM cycle reveals the dominant microinstabilities at perpendicular wavelengths of the order of the ion Larmor radius. These are kinetic ballooning modes (KBMs) in the pedestal and microtearing modes (MTMs) in the core close to the pedestal top. The evolving growth rate spectra, supported by gyrokinetic analysis using artificial local equilibrium scans, suggest a new physical picture for the formation and arrest of this pedestal.Comment: Final version as it appeared in PRL (March 2012). Minor improvements include: shortened abstract, and better colour table for figures. 4 pages, 6 figure
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