1,510 research outputs found
Letter to the editor concerning the article “Performance of gymnastics skill benefits from an external focus of attention” by Abdollahipour, Wulf, Psotta & Nieto (2015)
Abdollahipour, Wulf, Psotta, & Nieto (2015) recently published data in Journal of Sports Sciences to show that an external focus of attention promotes superior performance effects (gymnastics jump height and judged movement form score) when compared to internal or control foci during skill execution without an implement involved. While we do not contest the veracity of findings reported, nor others that have been used to support beneficial effects of an external focus of attention, in this Letter to the Editor we comment on considerable methodological limitations associated with this and previous studies which, we suggest, have resulted in serious theoretical oversights regarding the control of movement and, most crucially from our practitioner perspective, suboptimal recommendations for applied coaching practice. Specifically, we discuss the lack of consideration towards translational research in this area, the problematic nature of attentional focus cues employed, interpretation of findings in relation to other applied recommendations and coherence with mechanistic underpinning and finally, the representative nature of task involved. In summary, while (laboratory) research evidence may appear to be conclusive, we suggest that focus of attention effects are in need of more ecologically valid and rigorous testing and consideration of current coaching practices if it is to optimally serve the applied sporting domain that it purportedly aims to
Anomalous Elasticity of Polymer Cholesterics
We show that polymer cholesterics have much longer pitches than comparable
short molecule cholesterics, due to their anomalous elasticity. The pitch
of a chiral mixture with concentration near the racemic (non-chiral)
concentration diverges like with (for short molecule cholesterics ). The short molecule law is
recovered for polymers of finite molecular length once the pitch is
longer than a length that diverges like with . Our predictions could be tested by measurements of the pitch in DNA.Comment: 12 pages, Plain TeX, (1 postscript figure, compressed, uuencoded and
appended to paper), minor corrections, IASSNS-HEP-94/4
An evaluation of potentially useful separator materials for nickel-cadmium (Ni-Cd] satellite batteries
An evaluation intended to determine the potential suitability and probable efficacy of a group of separator materials for use in nickel-cadmium (Ni-Cd) satellite batteries was carried out. These results were obtained using test procedures established in an earlier evaluation of other separator materials, some of which were used in experimental battery cells subjected to simulated use conditions. The properties that appear to be most important are: high electrolyte absorptivity, good electrolyte retention, low specific resistivity, rapid wettability and low resistance to air permeation. Wicking characteristics and wet-out time seem to be more important with respect to the initial filling of the battery with the electrolyte
A New Phase of Tethered Membranes: Tubules
We show that fluctuating tethered membranes with {\it any} intrinsic
anisotropy unavoidably exhibit a new phase between the previously predicted
``flat'' and ``crumpled'' phases, in high spatial dimensions where the
crumpled phase exists. In this new "tubule" phase, the membrane is crumpled in
one direction but extended nearly straight in the other. Its average thickness
is with the intrinsic size of the membrane. This phase
is more likely to persist down to than the crumpled phase. In Flory
theory, the universal exponent , which we conjecture is an exact
result. We study the elasticity and fluctuations of the tubule state, and the
transitions into it.Comment: 4 pages, self-unpacking uuencoded compressed postscript file with
figures already inside text; unpacking instructions are at the top of file.
To appear in Phys. Rev. Lett. November (1995
A Reanalysis of the Hydrodynamic Theory of Fluid, Polar-Ordered Flocks
I reanalyze the hydrodynamic theory of fluid, polar ordered flocks. I find
new linear terms in the hydrodynamic equations which slightly modify the
anisotropy, but not the scaling, of the damping of sound modes. I also find
that the nonlinearities allowed {\it in equilibrium} do not stabilize long
ranged order in spatial dimensions ; in accord with the Mermin-Wagner
theorem. Nonequilibrium nonlinearities {\it do} stabilize long ranged order in
, as argued by earlier work. Some of these were missed by earlier work; it
is unclear whether or not they change the scaling exponents in .Comment: 6 pages, no figures. arXiv admin note: text overlap with
arXiv:0909.195
Molecular noise induces concentration oscillations in chemical systems with stable node steady states
Authentic recipes from around the world
This general audience book is the outcome of the AHRC project "Consuming Authenticities: Time, Place and the Past in the Construction of Authentic Foods and Drinks." It addresses the temporal relationships and ideas that contribute to the construction of narratives of authenticity in relation to four foods and drinks: pulque (an alcoholic drink from Central Mexico), flaounes (celebration Easter pies from Cyprus), Welsh craft cider and acarajé (a street snack from Brazil)
Quenched Dislocation Enhanced Supersolid Ordering
I show using Landau theory that quenched dislocations can facilitate the
supersolid (SS) to normal solid (NS) transition, making it possible for the
transition to occur even if it does not in a dislocation-free crystal. I make
detailed predictions for the dependence of the SS to NS transition temperature
T_c(L), superfluid density %\rho_S(T, L), and specific heat C(T,L) on
temperature T and dislocation spacing L, all of which can be tested against
experiments. The results should also be applicable to an enormous variety of
other systems, including, e.g., ferromagnets.Comment: 5 pages, 2 figure
Self-organization in systems of self-propelled particles
We investigate a discrete model consisting of self-propelled particles that
obey simple interaction rules. We show that this model can self-organize and
exhibit coherent localized solutions in one- and in two-dimensions.In
one-dimension, the self-organized solution is a localized flock of finite
extent in which the density abruptly drops to zero at the edges.In
two-dimensions, we focus on the vortex solution in which the particles rotate
around a common center and show that this solution can be obtained from random
initial conditions, even in the absence of a confining boundary. Furthermore,
we develop a continuum version of our discrete model and demonstrate that the
agreement between the discrete and the continuum model is excellent.Comment: 4 pages, 5 figure
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