8,761 research outputs found

    Hybrid Focal Stereo Networks for Pattern Analysis in Homogeneous Scenes

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    In this paper we address the problem of multiple camera calibration in the presence of a homogeneous scene, and without the possibility of employing calibration object based methods. The proposed solution exploits salient features present in a larger field of view, but instead of employing active vision we replace the cameras with stereo rigs featuring a long focal analysis camera, as well as a short focal registration camera. Thus, we are able to propose an accurate solution which does not require intrinsic variation models as in the case of zooming cameras. Moreover, the availability of the two views simultaneously in each rig allows for pose re-estimation between rigs as often as necessary. The algorithm has been successfully validated in an indoor setting, as well as on a difficult scene featuring a highly dense pilgrim crowd in Makkah.Comment: 13 pages, 6 figures, submitted to Machine Vision and Application

    Hemiparasitic plant impacts animal and plant communities across four trophic levels

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    1.Understanding the impact of species on community structure is a fundamental question in ecology. There is a growing body of evidence that suggests that both sub-dominant species and parasites can have a disproportionately large impact. 2.Here we report the impacts of an organism that is both subdominant and parasitic, the hemiparasite Rhinanthus minor. Whilst the impact of parasitic angiosperms on their hosts and, to a lesser degree, co-existing plant species, have been well characterized, much less is known about their impacts on higher trophic levels. 3.We experimentally manipulated field densities of the hemiparasite Rhinanthus minor in a species rich grassland, comparing the plant and invertebrate communities in plots where it was removed, at natural densities or at enhanced densities. 4.Plots with natural and enhanced densities of R. minor had lower plant biomass than plots without the hemiparasite, but enhanced densities almost doubled the abundance of invertebrates within the plots across all trophic levels, with effects evident in herbivores, predators and detritivores. 5.The hemiparasite R. minor, despite being a sub-dominant and transient component within plant communities that it inhabits, has profound effects on four different trophic levels. These effects persist beyond the life of the hemiparasite, emphasizing its role as a keystone species in grassland communitie

    Reactive oxygen species induce virus-independent MAVS-oligomerization in systemic lupus erythematosus

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    The increased expression of genes induced by type I interferon (IFN) is characteristic of viral infections and systemic lupus erythematosus (SLE). We showed that mitochondrial antiviral signaling (MAVS) protein, which normally forms a complex with retinoic acid gene I (RIG-I)–like helicases during viral infection, was activated by oxidative stress independently of RIG-I helicases. We found that chemically generated oxidative stress stimulated the formation of MAVS oligomers, which led to mitochondrial hyperpolarization and decreased adenosine triphosphate production and spare respiratory capacity, responses that were not observed in similarly treated cells lacking MAVS. Peripheral blood lymphocytes of SLE patients also showed spontaneous MAVS oligomerization that correlated with the increased secretion of type I IFN and mitochondrial oxidative stress. Furthermore, inhibition of mitochondrial reactive oxygen species (ROS) by the mitochondria-targeted antioxidant MitoQ prevented MAVS oligomerization and type I IFN production. ROS-dependent MAVS oligomerization and type I IFN production were reduced in cells expressing the MAVS-C79F variant, which occurs in 30% of sub-Saharan Africans and is linked with reduced type I IFN secretion and milder disease in SLE patients. Patients expressing the MAVS-C79F variant also had reduced amounts of oligomerized MAVS in their plasma compared to healthy controls. Together, our findings suggest that oxidative stress–induced MAVS oligomerization in SLE patients may contribute to the type I IFN signature that is characteristic of this syndrome

    Nature versus Nurture: The curved spine of the galaxy cluster X-ray luminosity -- temperature relation

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    The physical processes that define the spine of the galaxy cluster X-ray luminosity -- temperature (L-T) relation are investigated using a large hydrodynamical simulation of the Universe. This simulation models the same volume and phases as the Millennium Simulation and has a linear extent of 500 h^{-1} Mpc. We demonstrate that mergers typically boost a cluster along but also slightly below the L-T relation. Due to this boost we expect that all of the very brightest clusters will be near the peak of a merger. Objects from near the top of the L-T relation tend to have assembled much of their mass earlier than an average halo of similar final mass. Conversely, objects from the bottom of the relation are often experiencing an ongoing or recent merger.Comment: 8 pages, 7 figures, submitted to MNRA

    Addressing road-river infrastructure gaps using a model-based approach

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    The world's rivers are covered over and fragmented by road infrastructure. Road-river infrastructure result in many socio-environmental questions and documenting where different types occur is challenged by their sheer numbers. Equally, the United Nations has committed the next decade to ecosystem restoration, and decision makers across government, non-government, and private sectors require information about where different types of road-river infrastructure occur to guide management decisions that promote both transport and river system resilience. Field-based efforts alone cannot address data and information needs at relevant scales, such as across river basins, nations, or regions to guide road-river infrastructure remediation. As a first step toward overcoming these data needs in Great Britain, we constructed a georeferenced database of road-river infrastructure, validated a subset of locations, and used a Boosted Regression Tree model-based approach with environmental data to predict which infrastructure are bridges and culverts. We mapped 110,406 possible road-river infrastructure locations and were able to either validate or predict which of 110,194 locations were bridges (n=60,385) or culverts (n=49,809). Upstream drainage area had the greatest contribution to determining infrastructure type: when <10 km2 our model correctly predicted culverts 73% of the time but only 60% of the time for bridges. Road type and stream gradient also influenced model results. Our model-based approach is readily applied to other locations and contexts and can be used to inform decisions about management of smaller infrastructure that are frequently overlooked worldwide

    Galactic conformity and central/satellite quenching, from the satellite profiles of M* galaxies at 0.4 < z < 1.9 in the UKIDSS UDS

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    We explore the redshift evolution of a curious correlation between the star formation properties of central galaxies and their satellites (‘galactic conformity') at intermediate to high redshift (0.4 9.7, around central galaxies at the characteristic Schechter function mass, M ∼ M*. We fit the radial profiles of satellite number densities with simple power laws, finding slopes in the range −1.1 to −1.4 for mass-selected satellites, and −1.3 to −1.6 for passive satellites. We confirm the tendency for passive satellites to be preferentially located around passive central galaxies at 3σ significance and show that it exists to at least z ∼ 2. Meanwhile, the quenched fraction of satellites around star-forming galaxies is consistent with field galaxies of equal stellar masses. We find no convincing evidence for a redshift-dependent evolution of these trends. One simple interpretation of these results is that only passive central galaxies occupy an environment that is capable of independently shutting off star formation in satellite galaxies. By examining the satellites of higher stellar mass star-forming galaxies (log(M*/M⊙) > 11), we conclude that the origin of galactic conformity is unlikely to be exclusively due to the host dark matter halo mass. A halo-mass-independent correlation could be established by either formation bias or a more physical connection between central and satellite star formation histories. For the latter, we argue that a star formation (or active galactic nucleus) related outburst event from the central galaxy could establish a hot halo environment which is then capable of quenching both central and satellite galaxie

    Deep Learning for Vanishing Point Detection Using an Inverse Gnomonic Projection

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    We present a novel approach for vanishing point detection from uncalibrated monocular images. In contrast to state-of-the-art, we make no a priori assumptions about the observed scene. Our method is based on a convolutional neural network (CNN) which does not use natural images, but a Gaussian sphere representation arising from an inverse gnomonic projection of lines detected in an image. This allows us to rely on synthetic data for training, eliminating the need for labelled images. Our method achieves competitive performance on three horizon estimation benchmark datasets. We further highlight some additional use cases for which our vanishing point detection algorithm can be used.Comment: Accepted for publication at German Conference on Pattern Recognition (GCPR) 2017. This research was supported by German Research Foundation DFG within Priority Research Programme 1894 "Volunteered Geographic Information: Interpretation, Visualisation and Social Computing

    Collaboration and teamwork: immersion and presence in an online learning environment

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    In the world of OTIS, an online Internet School for occupational therapists, students from four European countries were encouraged to work collaboratively through problem-based learning by interacting with each other in a virtual semi-immersive environment. This paper describes, often in their own words, the experience of European occupational therapy students working together across national and cultural boundaries. Collaboration and teamwork were facilitated exclusively through an online environment, since the students never met each other physically during the OTIS pilot course. The aim of the paper is to explore the observations that here was little interaction between students from different tutorial groups and virtual teamwork developed in each of the cross-cultural tutorial groups. Synchronous data from the students was captured during tutorial sessions and peer-booked meetings and analysed using the qualitative constructs of ‘immersion’, ‘presence’ and ‘reflection in learning’. The findings indicate that ‘immersion’ was experienced only to a certain extent. However, both ‘presence’ and shared presence were found by the students, within their tutorial groups, to help collaboration and teamwork. Other evidence suggests that communities of interest were established. Further study is proposed to support group work in an online learning environment. It is possible to conclude that collaborative systems can be designed, which encourage students to build trust and teamwork in a cross cultural online learning environment.</p

    Common Practices of Australian Speech-Language Pathologists in the Management of Paediatric Vocal Health

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    Speech-Language Pathology Session IBConference Theme: Care of the Professional VoiceObjective: This study aimed to determine the common approaches taken by Australian speech language pathologists (SLPs) in the management of paediatric voice caseloads. Methods & Results: Forty-eight Australian SLPs with a current paediatric voice caseload completed an online questionnaire containing 38-items related to assessment, treatment and discharge procedures used in managing a paediatric voice caseload. Paediatric voice comprised between 1-100% of the respondents’ caseloads (M = 8.27%, SD = 17.71). Eight respondents (16.6%) considered themselves to be a voice specialist. Perceptual ratings of voice disorders were used more frequently than instrumental assessment tools throughout the management process. Respondents considered instrumental assessment by an Ear Nose and Throat (ENT) specialist to be important however reported barriers related to ENT service constraints (e.g., ENT availability and long waiting lists) and the associated cost to the client. A range of direct and indirect voice therapy approaches (often in combination) were employed by the respondents, usually determined by client specific factors. Respondents reported that it was more common for patients to be formally discharged (M= 42.32%; SD=41.1) than to self-discharge (M=24.71%; SD=31.78). The most commonly used outcome measures were clinician judgement, pre/post voice recording comparison, and review of results from a follow-up ENT assessment. Quality of life scales were rarely used as outcome measures. The majority of clinicians (56.25%, n = 27/48) indicated that they did not feel confident when managing children with voice disorders, and would welcome further training in the area. Conclusion: This investigation captured current practice of Australian SLPs managing paediatric voice caseloads. This data allows for comparison with management approaches in other countries. The findings highlight a need for further training in this area, particularly to enhance translation of recent research evidence into clinical practice.published_or_final_versio

    Leading through agonistic conflict: Contested sense-making in national political arenas

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    This article examines the social processes of political leadership in situations of contest and conflict, taking place within a key and long-established democratic institution, the UK Parliament. The empirical focus is on leadership in House of Commons select committees, which are concerned with holding the government to account. Headlines and media scrutiny, combined with internal challenge from the cross-party mix of politicians on the committees and a range of external stakeholders, create leadership challenges for committee chairs. The study is of two committee inquiries led by the same committee chair, which occurred concurrently and in real time, thereby providing a rare comparative study of leadership through the same leader at the same time but with different leadership challenges. Rather than shying away from conflict, as does much of the leadership literature, this research highlights how leaders who actively engage in challenge and conflict can build a degree of shared purpose among diverse groups of stakeholders. It examines and combines, in theory elaboration, two theories relevant to understanding these leadership processes: agonistic pluralism with its role in creating respectful conflictual consensus, and the theory of sense-making and sense-giving. The two cases (the two inquiries) had different trajectories and reveal how the chair recognised and dealt with conflict to achieve sense-making outcomes across divergent interests and across political parties. There are implications not only for understanding political leadership but also more widely for leadership where there are diverse and sometimes conflicting interests
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