3,804 research outputs found
Does kinesiology taping of the ankles affect proprioceptive control in professional football (soccer) players?
Abstract
Objective
To determine whether the bilateral application of kinesiology tape (KT) to professional footballers' ankles can improve their lower limb proprioception.
Design
A single blind randomised crossover study. Participants were randomly assigned to complete a proprioception test in either a taped or not taped condition first. Following a wash out period, participants were then re-tested in the alternate condition.
Setting
A UK Championship League Football Club, mid-season.
Participants
Twenty male professional football players over the age of 18, currently match fit with no injuries.
Outcome measure
Proprioception was assessed by participants undertaking the moving target program on the balance module attached to a Kin-Com 125AP isokinetic dynamometer. A paired sample two tailed t-test was used to assess whether there was a significant difference between the participants test scores in the not taped and taped conditions.
Results
The bilateral application of KT to professional footballers' ankles did not bring about a significant change in participants' scores when tested with a fine movement and balance control test. Percentage accuracy score mean difference 4.2 (p = 0.285).
Conclusion
The results of this study do not support the use of KT when applied to the ankles of healthy footballers as a method of improving proprioception
Phase-space structure of two-dimensional excitable localized structures
In this work we characterize in detail the bifurcation leading to an
excitable regime mediated by localized structures in a dissipative nonlinear
Kerr cavity with a homogeneous pump. Here we show how the route can be
understood through a planar dynamical system in which a limit cycle becomes the
homoclinic orbit of a saddle point (saddle-loop bifurcation). The whole picture
is unveiled, and the mechanism by which this reduction occurs from the full
infinite-dimensional dynamical system is studied. Finally, it is shown that the
bifurcation leads to an excitability regime, under the application of suitable
perturbations. Excitability is an emergent property for this system, as it
emerges from the spatial dependence since the system does not exhibit any
excitable behavior locally.Comment: 10 pages, 9 figure
From one- to two-dimensional solitons in the Ginzburg-Landau model of lasers with frequency selective feedback
We use the cubic complex Ginzburg-Landau equation coupled to a dissipative
linear equation as a model of lasers with an external frequency-selective
feedback. It is known that the feedback can stabilize the one-dimensional (1D)
self-localized mode. We aim to extend the analysis to 2D stripe-shaped and
vortex solitons. The radius of the vortices increases linearly with their
topological charge, , therefore the flat-stripe soliton may be interpreted
as the vortex with , while vortex solitons can be realized as stripes
bent into rings. The results for the vortex solitons are applicable to a broad
class of physical systems. There is a qualitative agreement between our results
and those recently reported for models with saturable nonlinearity.Comment: Submitted to PR
Drifting instabilities of cavity solitons in vertical cavity surface-emitting lasers with frequency selective feedback
In this paper we study the formation and dynamics of self-propelled cavity
solitons (CSs) in a model for vertical cavity surface-emitting lasers (VCSELs)
subjected to external frequency selective feedback (FSF), and build their
bifurcation diagram for the case where carrier dynamics is eliminated. For low
pump currents, we find that they emerge from the modulational instability point
of the trivial solution, where traveling waves with a critical wavenumber are
formed. For large currents, the branch of self-propelled solitons merges with
the branch of resting solitons via a pitchfork bifurcation. We also show that a
feedback phase variation of 2\pi can transform a CS (whether resting or moving)
into a different one associated to an adjacent longitudinal external cavity
mode. Finally, we investigate the influence of the carrier dynamics, relevant
for VCSELs. We find and analyze qualitative changes in the stability properties
of resting CSs when increasing the carrier relaxation time. In addition to a
drifting instability of resting CSs, a new kind of instability appears for
certain ranges of carrier lifetime, leading to a swinging motion of the CS
center position. Furthermore, for carrier relaxation times typical of VCSELs
the system can display multistability of CSs.Comment: 11 pages, 12 figure
Frequency and phase locking of laser cavity solitons
Self-localized states or dissipative solitons have the freedom of translation in systems with a homogeneous background. When compared to cavity solitons in coherently driven nonlinear optical systems, laser cavity solitons have the additional freedom of the optical phase. We explore the consequences of this additional Goldstone mode and analyse experimentally and numerically frequency and phase locking of laser cavity solitons in a vertical-cavity surface-emitting laser with frequency-selective feedback. Due to growth-related variations of the cavity resonance, the translational symmetry is usually broken in real devices. Pinning to different defects means that separate laser cavity solitons have different frequencies and are mutually incoherent. If two solitons are close to each other, however, their interaction leads to synchronization due to phase and frequency locking with strong similarities to the Adler-scenario of coupled oscillators
Using psychological and physiological measures in arts-based activities in a community sample of people with a dementia and their caregivers: a feasibility and pilot study
Introduction: Nearly all community-based dementia care studies employ either qualitative methods or use a combination of self-report questionnaire within mixed-methods research designs. Physiological measures, however, are rarely used in community-based studies with this population yet could provide valuable biological information for specific activities across the course of the dementias.
Method: The study employed a within-subjects design to assess the feasibility of obtaining physiological measures (salivary cortisol and Heart Rate Variability (HRV)) alongside subjective measures of wellbeing and stress using Visual Analogue Scales (VAS) during two community-based activiti of choral singing and art viewing, respectively, for People With Dementia (PWD) in the early to middle stages of impairment and their caregivers.
Results: As anticipated, pre-post subjective wellbeing measures were relatively easy to complete by PWD and caregivers with no substantive difficulties observed or reported; significant increases in composite wellbeing, happiness and optimism were found. Continuous measurement of physiological data of HRV through a sensor-based device (Empatica® E4) was also found to be neither non-intrusive to participants nor disruptive to the interventions. Preliminary indications showed, for example, HRV significantly increased for PWD during choral singing, which may be associated
with an increase in wellbeing. Measuring stress hormones through pre-post saliva samples, however, encountered several difficulties.
Conclusions: The findings provide support for the feasibility of using non-intrusive sensor-based physiological measures alongside subjective measures for this population. Subjective measures may also give more confidence in interpreting directionality of physiological measures. A full pilot study is warranted to further investigate interactions of physiological and psychological variables in choral singing and viewing art activities but it is uncertain whether measuring stress hormones through saliva collection is feasible for this population and raised doubts about their use in a large scale trial. Holding particular promise is the use of sensor-based technology across different stages of dementia as well as across different activities
Fluctuations and correlations in hexagonal optical patterns
We analyze the influence of noise in transverse hexagonal patterns in
nonlinear Kerr cavities. The near field fluctuations are determined by the
neutrally stable Goldstone modes associated to translational invariance and by
the weakly damped soft modes. However these modes do not contribute to the far
field intensity fluctuations which are dominated by damped perturbations with
the same wave vectors than the pattern. We find strong correlations between the
intensity fluctuations of any arbitrary pair of wave vectors of the pattern.
Correlation between pairs forming 120 degrees is larger than between pairs
forming 180 degrees, contrary to what a naive interpretation of emission in
terms of twin photons would suggest.Comment: 10 pages, 13 figure
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