3,077 research outputs found

    On the Two-View Geometry of Unsynchronized Cameras

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    We present new methods for simultaneously estimating camera geometry and time shift from video sequences from multiple unsynchronized cameras. Algorithms for simultaneous computation of a fundamental matrix or a homography with unknown time shift between images are developed. Our methods use minimal correspondence sets (eight for fundamental matrix and four and a half for homography) and therefore are suitable for robust estimation using RANSAC. Furthermore, we present an iterative algorithm that extends the applicability on sequences which are significantly unsynchronized, finding the correct time shift up to several seconds. We evaluated the methods on synthetic and wide range of real world datasets and the results show a broad applicability to the problem of camera synchronization.Comment: 12 pages, 9 figures, Computer Vision and Pattern Recognition (CVPR) 201

    Using a wireless consumer accelerometer to measure tibial acceleration during running : agreement with a skin mounted sensor

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    Real-time monitoring and feedback of tibial acceleration using wireless skin mounted sensors may reduce the risk of tibial stress fractures in runners. The purpose of this study was to assess the agreement between a wireless accelerometer and a gold standard reference accelerometer, both skin mounted, in measuring peak axial tibial acceleration when treadmill running at a range of speeds. A research grade accelerometer was mounted to a wireless accelerometer and attached to the tibia. Peak positive tibial accelerations of 13 participants were compared at 2.5 m.s-1, 3.5 m.s-1 and 4.5 m.s-1. Intraclass correlation coefficients demonstrated good agreement, with limits of agreement showing accuracy to within 1.2 – 1.65 g. The wireless accelerometer has scope to be used as a tool to measure peak tibial accelerations during running for the purpose of real-time feedback in gait training systems

    The use of biofeedback for gait retraining: A mapping review

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    Background: Biofeedback seems to be a promising tool to improve gait outcomes for both healthy individuals and patient groups. However, due to differences in study designs and outcome measurements, it remains uncertain how different forms of feedback affect gait outcomes. Therefore, the aim of this study is to review primary biomechanical literature which has used biofeedback to alter gait-related outcomes in human participants. Methods: Medline, Cinahl, Cochrane, SPORTDiscus and Pubmed were searched from inception to December 2017 using various keywords and the following MeSHterms: biofeedback, feedback, gait, walking and running. From the included studies, sixteen different study characteristics were extracted. Findings: In this mapping review 173 studies were included. The most common feedback mode used was visual feedback (42%, n=73) and the majority fed-back kinematic parameters (36%, n=62). The design of the studies were poor: only 8% (n=13) of the studies had both a control group and a retention test; 69% (n=120) of the studies had neither. A retention test after 6 months was performed in 3% (n=5) of the studies, feedback was faded in 9% (n=15) and feedback was given in the field rather than the laboratory in 4% (n=8) of the studies. Interpretation: Further work on biofeedback and gait should focus on the direct comparison between different modes of feedback or feedback parameters, along with better designed and field based studies

    Foot strike patterns in runners wearing floating heel, minimalist and conventional footwear

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    The purpose of this study was investigate the vertical loading rate and footstrike angles when running in floating heel shoes (a new concept called FBR (Faster and Better Runners) compared to conventional and minimalist shoes. Footstrike angle and force data were collected from 15 male recreational runners as they ran in three different footwear conditions, floating heel, conventional and minimalist shoes. Results revealed that running in floating heel shoes promotes a non-rearfoot strike and results in reduced vertical loafing rates compared to both conventional and minimalist footwear. These findings suggest that floating heel shoes may offer a new way of running with a nonrearfoot strike without the risk of impact related injuries

    Characterizing the learning effect in response to biofeedback aimed at reducing tibial acceleration during running

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    Increased tibial acceleration has been found to be an important risk factor for tibial stress fractures. Interventions aimed at reducing this variable which found a beneficial effect include the use of biofeedback in gait retraining. However, no studies have focused on the time participants take to modify tibial acceleration, therefore we aimed to find the start of a learning plateau in this study. Six participants ran on a treadmill while multisensory feedback was given. A single-subject analysis was used to characterise the learning effects. All participants changed peak tibial acceleration within the first step of running in the feedback condition. Two participants further reduced tibial acceleration to reach a plateau within 120 steps. In four of the six participants a strong effect of the feedback was still present after a week. Further research is needed to optimise the use of biofeedback in reducing the prevalence of tibial stress fractures

    Relay exchanges in elite short track speed skating

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    In short track speed skating, the relay exchange provides an additional strategic component to races by allowing a team to change the skater involved in the pack race. Typically executed every 1 ½ laps, it is the belief of skaters and coaches that during this period of the race, time can be gained or lost due to the execution of the relay exchange. As such, the aim of this study was to examine the influence of the relay exchange on a team's progression through a 5000 m relay race. Using data collected from three World Cup relay events during the 2012-13 season, the time taken to complete the straight for the scenarios with and without the relay exchange were compared at different skating speeds for the corner exit prior to the straight. Overall, the influence of the relay exchange was found to be dependent on this corner exit speed. At slower corner exit speeds (12.01 - 13.5 m/s), relay exchange straight times were significantly faster than the free skating scenario (P < 0.01). Whilst at faster corner exit speeds (14.01 - 15 m/s), straight times were significantly slower (P < 0.001). The findings of this study suggest that the current norm of executing relay exchanges every 1 ½ laps may not be optimal. Instead, varying the frequency of relay exchange execution throughout the race could allow: (1) time to be gained relative to other teams; and (2) facilitate other race strategies by providing an improved opportunity to overtake

    The Mechanism of Flexible Controlling as an Innovative Method in Management of Corporate Structures

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    У статті представлений принцип дії механізму гнучкого контролінгу як інноваційного методу управління корпоративними структурами. Розглянуто принципи застосування даного методу як інструменту ефективного управління корпоративними структурами, що дозволяють забезпечити різноманітність і гнучкість процесів управління для досягнення поставлених цілей. Розглянуто особливості контролінгу в управлінні корпоративними структурами в умовах нестабільного економічного середовища. Подано концепцію механізму контролінгу в управлінні корпоративними структурами, яка дозволяє забезпечити необхідну різноманітність процесів управління для досягнення динамічного комплексу цілей. Розглянуто особливості функціонування корпоративних структур у нестабільному ринковому оточенні. На прикладі механізму гнучкого контролінгу як способу адаптації до реалій сформованої нестабільності в економіці України представлена його здатність оперативно і тонко спрямовувати управління корпоративними структурами для прийняття правильних рішень та погодження роботи всіх підсистем підприємства.В статье представлен принцип действия механизма гибкого контроллинга как инновационного метода управления корпоративными структурами. Рассмотрены принципы применения данного метода как инструмента эффективного управления корпоративными структурами, позволяющие обеспечить разнообразие и гибкость процессов управления для достижения поставленных целей. Рассмотрены особенности контроллинга в управлении корпоративными структурами в условиях нестабильной экономической среды. Представлена концепция механизма контроллинга в управлении корпоративными структурами, которая позволяет обеспечить необходимое разнообразие процессов управления для достижения динамического комплекса целей. Рассмотрены особенности функционирования корпоративных структур в нестабильном рыночном окружении. На примере механизма гибкого контроллинга как способа адаптации к реалиям сложившейся нестабильности в экономике Украины представлена его способность оперативно и тонко направлять управление корпоративными структурами для принятия правильных решений и согласования работы всех подсистем предприятия.This article presents the principle of the mechanism controlling the flexible as an innovative method of managing corporate structures. The principles of this method as a tool for the effective management of corporate structures, allowing for variety and flexibility of management processes to achieve their goals. Features of controlling in management of corporate structures in the conditions of the unstable economic environment are considered. The concept of the mechanism of controlling in management of corporate structures which allows to provide a necessary variety of management processes for achievement of a dynamic complex of the purposes is presented. Features of functioning of corporate structures in an unstable market environment are considered. On the example of controlling a flexible mechanism as a way of adapting to the realities of the current instability in the economy of Ukraine, represented by its ability to quickly and subtly direct the management of the corporate structure to make the right decisions and coordination of all sub-systems of the enterprise

    Threonine 149 Phosphorylation Enhances  ΔFosB Transcriptional Activity to Control Psychomotor Responses to Cocaine

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    Stable changes in neuronal gene expression have been studied as mediators of addicted states. Of particular interest is the transcription factor ΔFosB, a truncated and stable FosB gene product whose expression in nucleus accumbens (NAc), a key reward region, is induced by chronic exposure to virtually all drugs of abuse and regulates their psychomotor and rewarding effects. Phosphorylation at Ser[superscript 27] contributes to ΔFosB's stability and accumulation following repeated exposure to drugs, and our recent work demonstrates that the protein kinase CaMKIIα phosphorylates ΔFosB at Ser[superscript 27] and regulates its stability in vivo. Here, we identify two additional sites on ΔFosB that are phosphorylated in vitro by CaMKIIα, Thr[superscript 149] and Thr[superscript 180], and demonstrate their regulation in vivo by chronic cocaine. We show that phosphomimetic mutation of Thr[superscript 149] (T149D) dramatically increases AP-1 transcriptional activity while alanine mutation does not affect transcriptional activity when compared with wild-type (WT) ΔFosB. Using in vivo viral-mediated gene transfer of ΔFosB-T149D or ΔFosB-T149A in mouse NAc, we determined that overexpression of ΔFosB-T149D in NAc leads to greater locomotor activity in response to an initial low dose of cocaine than does WT ΔFosB, while overexpression of ΔFosB-T149A does not produce the psychomotor sensitization to chronic low-dose cocaine seen after overexpression of WT ΔFosB and abrogates the sensitization seen in control animals at higher cocaine doses. We further demonstrate that mutation of Thr[superscript 149] does not affect the stability of ΔFosB overexpressed in mouse NAc, suggesting that the behavioral effects of these mutations are driven by their altered transcriptional properties

    Conceptual Change in Science Teaching and Learning: The Role of Pre-Instructional Conceptions

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     Conceptual change, defined as learning that requires the revision of prior knowledge and the acquisition of new concepts, is essential for learning in science. Research has often been framed in the context of misconceptions that need to be corrected. Conceptual change is difficult and essential and should be approached intentionally by recognizing that all learners (including students and teachers) bring pre-instructional conceptions to the classroom. A renewed emphasis for conceptual change research on practical classroom implementation of instructional strategies is necessary for science education to improve. This article builds on the theoretical work done by decades of researchers, while focusing on the real classroom research that has been done on intentional conceptual change. 
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