2,395 research outputs found

    Cooperative learning in multi-agent systems from intermittent measurements

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    Motivated by the problem of tracking a direction in a decentralized way, we consider the general problem of cooperative learning in multi-agent systems with time-varying connectivity and intermittent measurements. We propose a distributed learning protocol capable of learning an unknown vector μ\mu from noisy measurements made independently by autonomous nodes. Our protocol is completely distributed and able to cope with the time-varying, unpredictable, and noisy nature of inter-agent communication, and intermittent noisy measurements of μ\mu. Our main result bounds the learning speed of our protocol in terms of the size and combinatorial features of the (time-varying) networks connecting the nodes

    Nonuniform Coverage Control on the Line

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    This paper investigates control laws allowing mobile, autonomous agents to optimally position themselves on the line for distributed sensing in a nonuniform field. We show that a simple static control law, based only on local measurements of the field by each agent, drives the agents close to the optimal positions after the agents execute in parallel a number of sensing/movement/computation rounds that is essentially quadratic in the number of agents. Further, we exhibit a dynamic control law which, under slightly stronger assumptions on the capabilities and knowledge of each agent, drives the agents close to the optimal positions after the agents execute in parallel a number of sensing/communication/computation/movement rounds that is essentially linear in the number of agents. Crucially, both algorithms are fully distributed and robust to unpredictable loss and addition of agents

    LOCAL REGULATION OF DISCRIMINATORY EMPLOYMENT PRACTICES

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    Belated Recognition for Work Flow Entrepreneurs: A Case of Selective Perception and Amnesia in Management Thought

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    Recent trends, such as reengineering, require work flow entrepreneurship. Important principles about these practices were recognized in post-World War II field research, but by the 1970s this work suffered neglect. Amnesia was caused by deeply held assumptions of scientific management, and by a search within business schools for academic legitimacy at the expense of praxis, which skewed the perspectives with which organizations were viewed

    Food Environment, Built Environment, and Women\u27s BMI: Evidence from Erie County, New York

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    The authors present the results of a neighborhood-scaled exploratory study that tests the association of the food environment and the built environment with women’s body mass index (BMI) in Erie County, New York. The proximity of women’s homes to a supermarket relative to a convenience store is associated with lower BMI. A diverse land use mix in a neighborhood is positively associated with women’s BMI, especially when restaurants dominate nonresidential land use. The article offers suggestions for how food environments may be improved using planning strategies

    Addressing environmental and atmospheric challenges for capturing high-precision thermal infrared data in the field of astro-ecology

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    Using thermal infrared detectors mounted on drones, and applying techniques from astrophysics, we hope to support the field of conservation ecology by creating an automated pipeline for the detection and identification of certain endangered species and poachers from thermal infrared data. We test part of our system by attempting to detect simulated poachers in the field. Whilst we find that we can detect humans hiding in the field in some types of terrain, we also find several environmental factors that prevent accurate detection, such as ambient heat from the ground, absorption of infrared emission by the atmosphere, obscuring vegetation and spurious sources from the terrain. We discuss the effect of these issues, and potential solutions which will be required for our future vision for a fully automated drone-based global conservation monitoring system.Comment: Published in Proceedings of SPIE Astronomical Telescopes and Instrumentation 2018. 8 pages, 3 figure

    A Systematic Literature Review on Image Information Needs and Behaviors

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    Purpose: With ready access to search engines and social media platforms, the way people find image information has evolved and diversified in the past two decades. The purpose of this paper is to provide an overview of the literature on image information needs and behaviors. Design/methodology/approach: Following an eight-step procedure for conducting systematic literature reviews, the paper presents an analysis of peer-reviewed work on image information needs and behaviors, with publications ranging from the years 1997 to 2019. Findings: Application of the inclusion criteria led to 69 peer-reviewed works. These works were synthesized according to the following categories: research methods, users targeted, image types, identified needs, search behaviors, and search obstacles. The reviewed studies show that people seek and use images for multiple reasons, including entertainment, illustration, aesthetic appreciation, knowledge construction, engagement, inspiration, and social interactions. The reviewed studies also report that common strategies for image searches include keyword searches with short queries, browsing, specialization, and reformulation. Observed trends suggest common deployment of query analysis, survey questionnaires, and undergraduate participant pools to research image information needs and behavior. Originality: At this point, after more than two decades of image information needs research, a holistic systematic review of the literature was long overdue. The way users find image information has evolved and diversified due to technological developments in image retrieval. By synthesizing this burgeoning field into specific foci, this systematic literature review provides a foundation for future empirical investigation. With this foundation set, the paper then pinpoints key research gaps to investigate, particularly the influence of user expertise, a need for more diverse population samples, a dearth of qualitative data, new search features, and information and visual literacies instruction

    Postural control: the influence of vision to multi-muscle synergies

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    TITLE: Postural control: the influence of vision to multi-muscle synergies PRESENTATION TYPE: Research Report – Oral AUTHORS/INSTITUTIONS: A. Degani1, A. Danna-dos-Santos1, C. Leonard1. 1School of Physical Therapy and Rehabilitation Science, University of Montana, Missoula, MT. Significance: Falls are the leading cause of injury, deaths, and hospital admissions for traumatic injuries among people aged 65 years and older (Centers for Disease Control and Prevention, 2013). The costs related to the morbidity resulting from these falls are increasing dramatically. In order to reduce costs, increase quality of life, and prolong the longevity of the US work force, several studies are currently focusing on how to assess the risk of falls and prevent their occurrence. However, very little efforts is concentrated to the understanding of the neurophysiological mechanisms associated with upright postural control. Posture and postural reactions to mechanical perturbations require a precise harmonic modulation of the activity of multiple muscles. It is our premise that a comprehensive understanding of such neurophysiological mechanisms may improve current methods and/or result in the development of new approaches of assessing the risk and managing comorbidities generated by fall-related injuries. This study was designed to investigate the role of common neural inputs to the organization of multi-muscle synergies and the possible effects of disruption of visual input to this mechanism of control. Hypotheses: We hypothesize that (1) the central nervous system uses correlated neural inputs to coordinate the formation of postural muscle synergies, and (2) this mechanism is affected by the interruption of visual input. Methods: Our hypotheses were investigated by analyzing the strength and distribution of correlated neural inputs to postural muscles, as measured by electromyography (EMG) coherence, during the execution of a quiet stance tasks. Nine healthy participants, five females and four males with mean age of 26 years (± 6.1 SD) performed the task of maintaining a quiet stance on a force platform for 30 seconds under two experimental conditions: availability or absence of visual information (open eyes and closed eyes respectively). Center of pressure displacement were recorded by the force platform, and the activity of six postural muscles (soleus, biceps femoris, lumbar erector spinae, tibialis anterior, rectus femoris, and rectus abdominis) were recorded by surface electrodes. Intermuscular EMG-EMG coherence estimates were computed for all possible muscle pairs formed by these muscles. Pooled coherence estimations were also computed for anterior and posterior muscles. Results: Intermuscular coherence was found only to be significant within a distinct frequency band bounded between 1-10 Hz; and when visual information was available (“open eyes” trials). This significant coherence occurred only for muscle pairs formed solely by either posterior or anterior muscles. No synchronization patterns were observed for pairs of muscles formed by one anterior and one posterior muscle. In addition, the absence of visual information caused a significant decrease in intermuscular coherence estimates profiles within this same frequency band of 1-10Hz. Conclusion: These findings are consistent with the hypothesis that synchronization patterns of postural muscular activation are organized by correlated neural inputs. Moreover, the intermuscular coherence decreases significantly when the same task was performed under short-term absence of visual information. Clinical Relevance: Increased risk of falls is possibly linked to impairments in the ability of the neuromuscular system to generate optimal multi-muscle synergies. This impairment can result from several factors, such as poor vision caused by maculopathies. This study has provided a step forward towards the understanding of the mechanisms involved in coordination of multiple postural muscles, and the role of the vision on balance control. In addition, this study prepares the foundation for future clinical studies focusing on balance interventions for individuals with postural control disorders and/or visual impairments
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