3,531 research outputs found

    Impact differences among the landing phases of a drop vertical jump in soccer players

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    The aim of this study was to examine the differences of landing phase biomechanics between the players who had anterior cruciate ligament (ACL) reconstruction and healthy participants during single leg drop vertical jump. In this study, 11 soccer players who had anterior cruciate ligament reconstruction (aged 23.0±3.6 years, height 177±5.0 cm, weight 83.8±11.7 kg) and 9 healthy soccer players( aged 22.2±2.4 years, height 178±3.0 cm, weight 74.3±6.1 kg) participated voluntarily. During the data collection phase three high speed cameras synchronized to each other and force plate were used. Visual analysis programme and MATLAB were used to calculate kinetic and kinematic variables. Landing techniques of the subjects' were examined by flexion angle of knee, ground reaction force and moment parameters. The statistical analyses of the measured results were performed by t-test and Pearson Correlation analysis. According to the results, it was determined that peak vertical ground reaction force exhibited significant phase differences (p=0.00, and p=0.00, respectively) between the groups. Obtained results can be explained with "quadriceps avoidance" motion pattern which is characterized by decreased quadriceps activity and lower external knee flexion moment in an effort to control anterior translation of the tibia in subjects with ACL reconstruction. A better understanding of the different phases during single-leg landings can shed a light on mechanism of non-contact anterior crucaite ligament injuries therefore future researches should assess how phase differences affect drop vertical jump performance. © 2018 Montenegrin Sports Academy. All rights reserved

    Regression based polynomial chaos expansion for crop phenology estimation coupled with polsar imagery

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    Crop phenology monitoring using Synthetic Aperture Radar(SAR) data is gaining popularity within the remote sensing community due to SAR’s all weather and large coverage imaging capability. This paper introduces a polynomial chaos expansion (PCE) based regression algorithm to retrieve BBCH scale of crops, which identifies the phenology of crops in a standardized system. The impact and applicability of the proposed methodology is successfully illustrated using the TerraSAR-X dual-pol imagery that was acquired over the cultivation period of paddy-rice fields located in Turkey. To assess the applicability of the methodology, root mean square and correlation analysis were performed under different amount of training data and number of inputs

    MAC for Networks with Multipacket Reception Capability and Spatially Distributed Nodes

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    Discovery of Delta Scuti variables in eclipsing binary systems II.Southern TESS field search

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    The presence of pulsating stars in eclipsing binary systems (EBs) makes these objects significant since they allow us to investigate the stellar interior structure and evolution. Different types of pulsating stars could be found in EBs such as Delta Scuti variables. Delta Scuti stars in EBs have been known for decades and the increasing number of such systems is important for understanding pulsational structure. Hence, in this study, a research was carried out on the southern TESS field to discover new Delta Scuti stars in EBs. We produced an algorithm to search for detached and semi-detached EBs considering three steps; the orbital period (Porb_{orb})'s harmonics in the Fourier spectrum, skewness of the light curves, and classification of \textsc{UPSILON} program. If two of these steps classify a system as an EB, the algorithm also identifies it as an EB. The TESS pixel files of targets were also analyzed to see whether the fluxes are contaminated by other systems. No contamination was found. We researched the existence of pulsation through EBs with a visual inspection. To confirm Delta Scuti-type oscillations, the binary variation was removed from the light curve, and residuals were analyzed. Consequently, we identified 42 Delta Scuti candidates in EBs. The Porb_{orb}, LL, and MV_{V} of systems were calculated. Their positions on the H-R diagram and the known orbital-pulsation period relationship were analyzed. We also examined our targets to find if any of them show frequency modulation with the orbital period and discovered one candidate of tidally tilted pulsators.Comment: Published in MNRA

    IoTSan: Fortifying the Safety of IoT Systems

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    Today's IoT systems include event-driven smart applications (apps) that interact with sensors and actuators. A problem specific to IoT systems is that buggy apps, unforeseen bad app interactions, or device/communication failures, can cause unsafe and dangerous physical states. Detecting flaws that lead to such states, requires a holistic view of installed apps, component devices, their configurations, and more importantly, how they interact. In this paper, we design IoTSan, a novel practical system that uses model checking as a building block to reveal "interaction-level" flaws by identifying events that can lead the system to unsafe states. In building IoTSan, we design novel techniques tailored to IoT systems, to alleviate the state explosion associated with model checking. IoTSan also automatically translates IoT apps into a format amenable to model checking. Finally, to understand the root cause of a detected vulnerability, we design an attribution mechanism to identify problematic and potentially malicious apps. We evaluate IoTSan on the Samsung SmartThings platform. From 76 manually configured systems, IoTSan detects 147 vulnerabilities. We also evaluate IoTSan with malicious SmartThings apps from a previous effort. IoTSan detects the potential safety violations and also effectively attributes these apps as malicious.Comment: Proc. of the 14th ACM CoNEXT, 201

    A solvable model of the genesis of amino-acid sequences via coupled dynamics of folding and slow genetic variation

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    We study the coupled dynamics of primary and secondary structure formation (i.e. slow genetic sequence selection and fast folding) in the context of a solvable microscopic model that includes both short-range steric forces and and long-range polarity-driven forces. Our solution is based on the diagonalization of replicated transfer matrices, and leads in the thermodynamic limit to explicit predictions regarding phase transitions and phase diagrams at genetic equilibrium. The predicted phenomenology allows for natural physical interpretations, and finds satisfactory support in numerical simulations.Comment: 51 pages, 13 figures, submitted to J. Phys.

    A New Approach to Spin Glass Simulations

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    We present a recursive procedure to calculate the parameters of the recently introduced multicanonical ensemble and explore the approach for spin glasses. Temperature dependence of the energy, the entropy and other physical quantities are easily calculable and we report results for the zero temperature limit. Our data provide evidence that the large LL increase of the ergodicity time is greatly improved. The multicanonical ensemble seems to open new horizons for simulations of spin glasses and other systems which have to cope with conflicting constraints

    The order of the quantum chromodynamics transition predicted by the standard model of particle physics

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    We determine the nature of the QCD transition using lattice calculations for physical quark masses. Susceptibilities are extrapolated to vanishing lattice spacing for three physical volumes, the smallest and largest of which differ by a factor of five. This ensures that a true transition should result in a dramatic increase of the susceptibilities.No such behaviour is observed: our finite-size scaling analysis shows that the finite-temperature QCD transition in the hot early Universe was not a real phase transition, but an analytic crossover (involving a rapid change, as opposed to a jump, as the temperature varied). As such, it will be difficult to find experimental evidence of this transition from astronomical observations.Comment: 7 pages, 4 figure

    Three Millisecond Pulsars in FERMI LAT Unassociated Bright Sources

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    We searched for radio pulsars in 25 of the non-variable, unassociated sources in the Fermi LAT Bright Source List with the Green Bank Telescope at 820 MHz. We report the discovery of three radio and gamma-ray millisecond pulsars (MSPs) from a high Galactic latitude subset of these sources. All of the pulsars are in binary systems, which would have made them virtually impossible to detect in blind gamma-ray pulsation searches. They seem to be relatively normal, nearby (<=2 kpc) millisecond pulsars. These observations, in combination with the Fermi detection of gamma-rays from other known radio MSPs, imply that most, if not all, radio MSPs are efficient gamma-ray producers. The gamma-ray spectra of the pulsars are power-law in nature with exponential cutoffs at a few GeV, as has been found with most other pulsars. The MSPs have all been detected as X-ray point sources. Their soft X-ray luminosities of ~10^{30-31} erg/s are typical of the rare radio MSPs seen in X-rays.Comment: Accepted for publication in ApJ Letter

    Observation and Spectral Measurements of the Crab Nebula with Milagro

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    The Crab Nebula was detected with the Milagro experiment at a statistical significance of 17 standard deviations over the lifetime of the experiment. The experiment was sensitive to approximately 100 GeV - 100 TeV gamma ray air showers by observing the particle footprint reaching the ground. The fraction of detectors recording signals from photons at the ground is a suitable proxy for the energy of the primary particle and has been used to measure the photon energy spectrum of the Crab Nebula between ~1 and ~100 TeV. The TeV emission is believed to be caused by inverse-Compton up-scattering scattering of ambient photons by an energetic electron population. The location of a TeV steepening or cutoff in the energy spectrum reveals important details about the underlying electron population. We describe the experiment and the technique for distinguishing gamma-ray events from the much more-abundant hadronic events. We describe the calculation of the significance of the excess from the Crab and how the energy spectrum is fit. The fit is consistent with values measured by IACTs between 1 and 20 TeV. Fixing the spectral index to values that have been measured below 1 TeV by IACT experiments (2.4 to 2.6), the fit to the Milagro data suggests that Crab exhibits a spectral steepening or cutoff between about 20 to 40 TeV.Comment: Submitted to Astrophysical Journa
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