190 research outputs found
Fatiguing Effects of Indirect Vibration Stimulation in Upper Limb Muscles- pre, post and during Isometric Contractions Superimposed on Upper Limb Vibration
© 2019 The Authors. Published by the Royal Society under the terms of the Creative Commons Attribution License http://creativecommons.org/licenses/by/4.0/ , which permits unrestricted use, provided the original author and source are credited.Whole-body vibration and upper limb vibration (ULV) continue to gain popularity as exercise intervention for rehabilitation and sports applications. However, the fatiguing effects of indirect vibration stimulation are not yet fully understood. We investigated the effects of ULV stimulation superimposed on fatiguing isometric contractions using a purpose developed upper limb stimulation device. Thirteen healthy volunteers were exposed to both ULV superimposed to fatiguing isometric contractions (V) and isometric contractions alone Control (C). Both Vibration (V) and Control (C) exercises were performed at 80% of the maximum voluntary contractions. The stimulation used was 30 Hz frequency of 0.4 mm amplitude. Surface-electromyographic (EMG) activity of the Biceps Brachii, Triceps Brachii and Flexor Carpi Radialis were measured. EMG amplitude (EMGrms) and mean frequency (MEF) were computed to quantify muscle activity and fatigue levels. All muscles displayed significantly higher reduction in MEFs and a corresponding significant increase in EMGrms with the V than the Control, during fatiguing contractions (p < 0.05). Post vibration, all muscles showed higher levels of MEFs after recovery compared to the control. Our results show that near-maximal isometric fatiguing contractions superimposed on vibration stimulation lead to a higher rate of fatigue development compared to the isometric contraction alone in the upper limb muscles. Results also show higher manifestation of mechanical fatigue post treatment with vibration compared to the control. Vibration superimposed on isometric contraction not only seems to alter the neuromuscular function during fatiguing efforts by inducing higher neuromuscular load but also post vibration treatment.Peer reviewedFinal Published versio
Long-term polarization observations of Mira variable stars suggest asymmetric structures
Mira and semi-regular variable stars have been studied for centuries but
continue to be enigmatic. One unsolved mystery is the presence of polarization
from these stars. In particular, we present 40 years of polarization
measurements for the prototype o Ceti and V CVn and find very different
phenomena for each star. The polarization fraction and position angle for Mira
is found to be small and highly variable. On the other hand, the polarization
fraction for V CVn is large and variable, from 2 - 7 %, and its position angle
is approximately constant, suggesting a long-term asymmetric structure. We
suggest a number of potential scenarios to explain these observations.Comment: 2 pages, 1 figure, poster presented at IAU Symposium 301, Precision
Asteroseismology, August 2013, Wroclaw, Polan
Upper limb vibration prototype with sports and rehabilitation applications : development, evaluation and preliminary study
Acknowledgment: This work was supported by the North East of Scotland Technology Seed Fund (NESTech) grant from Scottish Funding Council (SFC)Peer reviewedPublisher PD
Variable buoyancy anchor deployment analysis for floating wind applications using a Marine Simulator
The research presented in this paper has been primarily sponsored by EPSRCâs Supergen ORE Hub & ORE Catapult Floating Offshore Wind Centre of Excellence (grant number FF2021-1040). The authors acknowledge funding received from Energy Technology Partnership Knowledge Exchange Network scheme (grant number PR057-ME) that provided additional funding to support this work. The authors wish to thank Oceanetics Inc. and Aubin Group for their support towards this project. This work has benefited from the support and funding received from Net Zero Technology Centre and The University of Aberdeen through their partnership in The National Decommissioning Centre (NDC) and The Scottish Governmentâs Decommissioning Challenge Fund in part-funding the establishment of the Marine Simulator research facility at the NDC.Peer reviewedPublisher PD
A Multi-Year Photopolarimetric Study of the Semi-Regular Variable V CVn and Identification of Analogue Sources
The semi-regular variable star V Canum Venaticorum (V CVn) is well-known for
its unusual linear polarization position angle (PA). Decades of observing V CVn
reveal a nearly constant PA spanning hundreds of pulsation cycles. This
phenomenon has persisted through variability that has ranged by 2 magnitudes in
optical brightness and through variability in the polarization amplitude over
0.3% and 6.9%. Additionally, the polarization fraction of V CVn varies
inversely with brightness.
This paper presents polarization measurements obtained over three pulsation
cycles. We find that the polarization maximum does not always occur precisely
at the same time as the brightness minimum. Instead, we observe a small lead or
lag in relation to the brightness minimum, spanning a period of a few days up
to three weeks. Furthermore, the PA sometimes exhibits a non-negligible
rotation, especially at lower polarization levels.
To elucidate the unusual optical behavior of V CVn, we present a list of
literature sources that also exhibit polarization variability with a roughly
fixed PA. We find this correlation occurs in stars with high tangential space
velocities, i.e., "runaway" stars, suggesting that the long-term constant PA is
related to how the circumstellar gas is shaped by the star's high-speed motion
through the interstellar medium.Comment: 9 pages + appendices, 7 figures, accepted for publication in A&
Identifying the science and technology dimensions of emerging public policy issues through horizon scanning
Public policy requires public support, which in turn implies a need to enable the public not just to understand policy but also to be engaged in its development. Where complex science and technology issues are involved in policy making, this takes time, so it is important to identify emerging issues of this type and prepare engagement plans. In our horizon scanning exercise, we used a modified Delphi technique [1]. A wide group of people with interests in the science and policy interface (drawn from policy makers, policy adviser, practitioners, the private sector and academics) elicited a long list of emergent policy issues in which science and technology would feature strongly and which would also necessitate public engagement as policies are developed. This was then refined to a short list of top priorities for policy makers. Thirty issues were identified within broad areas of business and technology; energy and environment; government, politics and education; health, healthcare, population and aging; information, communication, infrastructure and transport; and public safety and national security.Public policy requires public support, which in turn implies a need to enable the public not just to understand policy but also to be engaged in its development. Where complex science and technology issues are involved in policy making, this takes time, so it is important to identify emerging issues of this type and prepare engagement plans. In our horizon scanning exercise, we used a modified Delphi technique [1]. A wide group of people with interests in the science and policy interface (drawn from policy makers, policy adviser, practitioners, the private sector and academics) elicited a long list of emergent policy issues in which science and technology would feature strongly and which would also necessitate public engagement as policies are developed. This was then refined to a short list of top priorities for policy makers. Thirty issues were identified within broad areas of business and technology; energy and environment; government, politics and education; health, healthcare, population and aging; information, communication, infrastructure and transport; and public safety and national security
First narrow-band search for continuous gravitational waves from known pulsars in advanced detector data
Spinning neutron stars asymmetric with respect to their rotation axis are potential sources of
continuous gravitational waves for ground-based interferometric detectors. In the case of known pulsars a
fully coherent search, based on matched filtering, which uses the position and rotational parameters
obtained from electromagnetic observations, can be carried out. Matched filtering maximizes the signalto-
noise (SNR) ratio, but a large sensitivity loss is expected in case of even a very small mismatch
between the assumed and the true signal parameters. For this reason, narrow-band analysis methods have
been developed, allowing a fully coherent search for gravitational waves from known pulsars over a
fraction of a hertz and several spin-down values. In this paper we describe a narrow-band search of
11 pulsars using data from Advanced LIGOâs first observing run. Although we have found several initial
outliers, further studies show no significant evidence for the presence of a gravitational wave signal.
Finally, we have placed upper limits on the signal strain amplitude lower than the spin-down limit for 5 of
the 11 targets over the bands searched; in the case of J1813-1749 the spin-down limit has been beaten for
the first time. For an additional 3 targets, the median upper limit across the search bands is below the
spin-down limit. This is the most sensitive narrow-band search for continuous gravitational waves carried
out so far
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