1,408 research outputs found

    Single-Pole Interaction of the Particle with the String

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    Within the framework of generalized Papapetrou method, we derive the effective equations of motion for a string with two particles attached to its ends, along with appropriate boundary conditions. The equations of motion are the usual Nambu-Goto-like equations, while boundary conditions turn out to be equations of motion for the particles at the string ends. Various properties of those equations are discussed, and a simple example is treated in detail, exhibiting the properties of Neumann and Dirichlet boundary conditions and giving a small correction term to the law of Regge trajectories due to the nonzero particle mass

    An Investigation into the Dissipation of Vibrations Using Electromyography towards the Development of Self-Adapting Robotic Prosthesis

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    Vibrations can be used to convey positional or sensory information to prosthetic users. However, for the feedback to convey information consistently, daily fine-grained adjustments are required. This paper investigates whether vibration dissipation through the muscle can be tracked using EMG with the aim of providing reliable, long-term sensory feedback. The results of this study showed that the magnitude of vibration artifacts can be measured using EMG and used to create a dissipation trend. This trend varies between participants but shows consistency for individuals when measured across multiple days. This novel way of measuring vibration dissipation can potentially be used as a basis for adaptive sensory control in future prosthesis studies

    Optimization of Adaptive Three-Mode GBN Scheme Control Parameters

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    An adaptive three-mode system based on mbox{Go-Back-N} (GBN) protocol is analyzed within this paper. An ideal mode selection procedure based on a-priori known packet error probability is defined. When packet error probability is unknown the system state transition is controlled by several system parameters. A procedure for optimal parameters selection is proposed and tested on a simulated system. The procedure is based on minimization of mean square deviation of the system throughput from the ideal one

    Developing Frameworks to Understand Disaster Causation: From Forensic Disaster Investigation to Risk Root Cause Analysis

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    Electronic version of an article published as Journal of Extreme Events, vol. 3, no. 2, 2016, pp. 1650008 (21 pp.). doi:10.1142/S2345737616500081 © copyright World Scientific Publishing Company, https://www.worldscientific.com/doi/abs/10.1142/S2345737616500081The research reported on in this paper was funded by the PEARL (or Preparing for Extreme And Rare events in coastaL regions) project, European Commission Seventh Framework Programme for Research under grant agreement number 603663

    Preliminary definitions for the sonographic features of synovitis in children

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    Objectives Musculoskeletal ultrasonography (US) has the potential to be an important tool in the assessment of disease activity in childhood arthritides. To assess pathology, clear definitions for synovitis need to be developed first. The aim of this study was to develop and validate these definitions through an international consensus process. Methods The decision on which US techniques to use, the components to be included in the definitions as well as the final wording were developed by 31 ultrasound experts in a consensus process. A Likert scale of 1-5 with 1 indicating complete disagreement and 5 complete agreement was used. A minimum of 80% of the experts scoring 4 or 5 was required for final approval. The definitions were then validated on 120 standardized US images of the wrist, MCP and tibiotalar joints displaying various degrees of synovitis at various ages. Results B-Mode and Doppler should be used for assessing synovitis in children. A US definition of the various components (i.e. synovial hypertrophy, effusion and Doppler signal within the synovium) was developed. The definition was validated on still images with a median of 89% (range 80-100) of participants scoring it as 4 or 5 on a Likert scale. Conclusions US definitions of synovitis and its elementary components covering the entire pediatric age range were successfully developed through a Delphi process and validated in a web-based still images exercise. These results provide the basis for the standardized US assessment of synovitis in clinical practice and research

    Amendment of the OMERACT ultrasound definitions of joints' features in healthy children when using the DOPPLER technique

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    Background: Recently preliminary ultrasonography (US) definitions, in B mode, for normal components of pediatric joints have been developed by the OMERACT US group. The aim of the current study was to include Doppler findings in the evaluation and definition of normal joint features that can be visualized in healthy children at different age groups. Methods: A multistep approach was used. Firstly, new additional definitions of joint components were proposed during an expert meeting. In the second step, these definitions, along with the preliminary B-mode-US definitions, were tested for feasibility in an exercise in healthy children at different age groups. In the last step, a larger panel of US experts were invited to join a web-based consensus process in order to approve the developed definitions using the Delphi methodology. A Likert scale of 1-5 was used to assess agreement. Results: Physiological vascularity and fat pad tissue were identified and tested as two additional joint components in healthy children. Since physiological vascularity changes over the time in the growing skeleton, the final definition of Doppler findings comprised separate statements instead of a single full definition. A total of seven statements was developed and included in a written Delphi questionnaire to define and validate the new components. The final definitions for fat pad and physiological vascularity agreed by the group of experts reached 92.9% and 100% agreement respectively in a web survey. Conclusion: The inclusion of these two additional joints components which are linked to detection of Doppler signal in pediatric healthy joints will improve the identification of abnormalities in children with joint pathologies

    Real-world comparison of the effects of etanercept and adalimumab on well-being in non-systemic juvenile idiopathic arthritis: a propensity score matched cohort study

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    Background: Etanercept (ETN) and adalimumab (ADA) are considered equally efective biologicals in the treat‑ ment of arthritis in juvenile idiopathic arthritis (JIA) but no studies have compared their impact on patient-reported well-being. The objective of this study was to determine whether ETN and ADA have a diferential efect on patientreported well-being in non-systemic JIA using real-world data. Methods: Biological-naive patients without a history of uveitis were selected from the international Pharmachild registry. Patients starting ETN were matched to patients starting ADA based on propensity score and outcomes were collected at time of therapy initiation and 3–12 months afterwards. Primary outcome at follow-up was the improve‑ ment in Juvenile Arthritis Multidimensional Assessment Report (JAMAR) visual analogue scale (VAS) well-being score from baseline. Secondary outcomes at follow-up were decrease in active joint count, adverse events and uveitis events. Outcomes were analyzed using linear and logistic mixed efects models. Results: Out of 158 eligible patients, 45 ETN starters and 45 ADA starters could be propensity score matched result‑ ing in similar VAS well-being scores at baseline. At follow-up, the median improvement in VAS well-being was 2 (inter‑ quartile range (IQR): 0.0 – 4.0) and scores were signifcantly better (P=0.01) for ETN starters (median 0.0, IQR: 0.0 – 1.0) compared to ADA starters (median 1.0, IQR: 0.0 – 3.5). The estimated mean diference in VAS well-being improvement from baseline for ETN versus ADA was 0.89 (95% CI: -0.01 – 1.78; P=0.06). The estimated mean diference in active joint count decrease was -0.36 (95% CI: -1.02 – 0.30; P=0.28) and odds ratio for adverse events was 0.48 (95% CI: 0.16 –1.44; P=0.19). One uveitis event was observed in the ETN group. Conclusions: Both ETN and ADA improve well-being in non-systemic JIA. Our data might indicate a trend towards a slightly stronger efect for ETN, but larger studies are needed to confrm this given the lack of statistical signifcance