1,433 research outputs found
Mental skills training in sprinting
The Science of Sport: Sprinting examines the scientific principles that underpin the preparation and performance of athletics at all levels, from grassroots to Olympic competition. Drawing on the expertise of some of the world's leading coaches and sport science professionals, the book presents a detailed analysis of the latest evidence and explores the ways in which science has influenced, and subsequently improved, the sport of sprinting.
By providing an overview of the principles of sport science and how these are applied in practice, the book is essential reading for students and academics, coaches and performers, physiotherapists, club doctors and professional support staff
Spacetime Slices and Surfaces of Revolution
Under certain conditions, a -dimensional slice of a
spherically symmetric black hole spacetime can be equivariantly embedded in
-dimensional Minkowski space. The embedding depends on a real parameter
that corresponds physically to the surface gravity of the black hole
horizon.
Under conditions that turn out to be closely related, a real surface that
possesses rotational symmetry can be equivariantly embedded in 3-dimensional
Euclidean space. The embedding does not obviously depend on a parameter.
However, the Gaussian curvature is given by a simple formula: If the metric is
written , then
\K_g=-{1/2}\phi''(r).
This note shows that metrics and occur in dual pairs, and that
the embeddings described above are orthogonal facets of a single phenomenon. In
particular, the metrics and their respective embeddings differ by a Wick
rotation that preserves the ambient symmetry.
Consequently, the embedding of depends on a real parameter. The ambient
space is not smooth, and is inversely proportional to the cone angle
at the axis of rotation. Further, the Gaussian curvature of is given
by a simple formula that seems not to be widely known.Comment: 15 pages, added reference
Drug and Alcohol-Related Workload of Anchorage Patrol Officers: Results From Two Patrol Officer Surveys
It is widely agreed among criminal justice professionals that alcohol and illegal drugs play a role in patterns of crime, but not much is known about how these substances influence the operation of criminal justice agencies, particularly in the area of policing. This report summarizes the findings of a study of the extent to which drug and alcohol-related incidents formed the workload of Anchorage Police Department patrol officers. The study consisted of two surveys, the first of which asked APD patrol officers to provide their best estimate of the amount of time they spent dealing with alcohol and drug-related activities, the second of which required patrol officers to complete incident logs describing drug and alcohol-related incidents encountered on patrol. The study found that officers tended to overestimate the amount of time they spent on drug or alcohol-related activities, but that the drug and alcohol-related activities nonetheless comprise a significant portion of APD patrol officers' workload.Acknowledgements / Executive Summary / List of Tables / List of Figures / Introduction / Methodology / Part I: Survey 1: Global Perceptions of Drug- and Alcohol-related Workload / Part II: Survey 2: Incident-based Perceptions of Drug- and Alcohol-related Workload / Part III: Comparing Officers’ Global Estimates to Incident Log Data / Part IV: Summary and Conclusions / Methodological Appendix / References / Note
Gravitational Wave Production At The End Of Inflation
We consider gravitational wave production due to parametric resonance at the
end of inflation, or ``preheating''. This leads to large inhomogeneities which
source a stochastic background of gravitational waves at scales inside the
comoving Hubble horizon at the end of inflation. We confirm that the present
amplitude of these gravitational waves need not depend on the inflationary
energy scale. We analyze an explicit model where the inflationary energy scale
is ~10^9 GeV, yielding a signal close to the sensitivity of Advanced LIGO and
BBO. This signal highlights the possibility of a new observational ``window''
into inflationary physics, and provides significant motivation for searches for
stochastic backgrounds of gravitational waves in the Hz to GHz range, with an
amplitude on the order of \Omega_{gw}(k)h^2 ~ 10^-11. Finally, the strategy
used in our numerical computations is applicable to the gravitational waves
generated by many inhomogeneous processes in the early universe.Comment: 4 pages, Revtex, 2 figures. v2 References added, discussion clarified
and improved. v3 further clarification, typo regarding source corrected.
Basic results unchange
Do anionic phospholipids serve as cofactors or second messengers for the regulation of activity of cloned ATP-sensitive K+ channels?
The regulation of ion channels by anionic phospholipids is currently very topical. An outstanding issue is whether phosphatidylinositol 4,5-diphosphate and related species act as true second messengers in signaling or behave in a manner analogous to an enzymatic cofactor. This question is especially pertinent regarding ATP-sensitive K+ channels in smooth muscle, for which there is substantial literature supporting inhibitory regulation by hormones. In this study, we have examined regulation of the potential cloned equivalents of the smooth muscle ATP-sensitive K+ channel (SUR2B/Kir6.1 and SUR2B/Kir6.2). We find that both can be inhibited via the G(q/11)-coupled muscarinic M3 receptor but that the pathways by which this occurs are different. Our data show that SUR2B/Kir6.1 is inhibited by protein kinase C and binds anionic phospholipids with high affinity, such that potential physiological fluctuations in their levels do not influence channel activity. In contrast, Kir6.2 is not regulated by protein kinase C but binds anionic phospholipids with low affinity. In this case, phosphatidylinositol 4,5-diphosphate and related species have the potential to act as second messengers in signaling. Thus, Kir6.1 and Kir6.2 are regulated by distinct inhibitory mechanisms
A New Mechanism for Bubble Nucleation: Classical Transitions
Given a scalar field with metastable minima, bubbles nucleate quantum
mechanically. When bubbles collide, energy stored in the bubble walls is
converted into kinetic energy of the field. This kinetic energy can facilitate
the classical nucleation of new bubbles in minima that lie below those of the
"parent" bubbles. This process is efficient and classical, and changes the
dynamics and statistics of bubble formation in models with multiple vacua,
relative to that derived from quantum tunneling.Comment: 4 pages, 4 figures, animations related to figures can be found at
http://www.perimeterinstitute.ca/personal/jgiblin/BubbleMovies.htm
How to Run Through Walls: Dynamics of Bubble and Soliton Collisions
It has recently been shown in high resolution numerical simulations that
relativistic collisions of bubbles in the context of a multi-vacua potential
may lead to the creation of bubbles in a new vacuum. In this paper, we show
that scalar fields with only potential interactions behave like free fields
during high-speed collisions; the kick received by them in a collision can be
deduced simply by a linear superposition of the bubble wall profiles. This
process is equivalent to the scattering of solitons in 1+1 dimensions. We
deduce an expression for the field excursion (shortly after a collision), which
is related simply to the field difference between the parent and bubble vacua,
i.e. contrary to expectations, the excursion cannot be made arbitrarily large
by raising the collision energy. There is however a minimum energy threshold
for this excursion to be realized. We verify these predictions using a number
of 3+1 and 1+1 numerical simulations. A rich phenomenology follows from these
collision induced excursions - they provide a new mechanism for scanning the
landscape, they might end/begin inflation, and they might constitute our very
own big bang, leaving behind a potentially observable anisotropy.Comment: 15pgs, 14 figures, v2, thanks for the feedback
Development of the Magnetic Excitations of Charge-Stripe Ordered La(2-x)Sr(x)NiO(4) on Doping Towards Checkerboard Charge Order
The magnetic excitation spectrums of charge stripe ordered La(2-x)Sr(x)NiO(4)
x = 0.45 and x = 0.4 were studied by inelastic neutron scattering. We found the
magnetic excitation spectrum of x = 0.45 from the ordered Ni^2+ S = 1 spins to
match that of checkerboard charge ordered La(1.5)Sr(0.5)NiO(4). The distinctive
asymmetry in the magnetic excitations above 40 meV was observed for both doping
levels, but an additional ferromagnetic mode was observed in x = 0.45 and not
in the x = 0.4. We discuss the origin of crossover in the excitation spectrum
between x = 0.45 and x = 0.4 with respect to discommensurations in the charge
stripe structure.Comment: 4 Figures. To be appear in the J. Kor. Phys. Soc. as a proceedings
paper from the ICM 2012 conferenc
β-Lactoglobulin-linoleate complexes: In vitro digestion and the role of protein in fatty acids uptake
peer-reviewedThe dairy protein β-lactoglobulin (BLG) is known to bind fatty acids such as the salt of the essential longchain fatty acid linoleic acid (cis,cis-9,12-octadecadienoic
acid, n-6, 18:2). The aim of the current study was to investigate how bovine BLG-linoleate complexes, of various stoichiometry, affect the enzymatic digestion
of BLG and the intracellular transport of linoleate into enterocyte-like monolayers. Duodenal and gastric digestions of the complexes indicated that BLG was hydrolyzed
more rapidly when complexed with linoleate.
Digested as well as undigested BLG-linoleate complexes reduced intracellular linoleate transport as compared with free linoleate. To investigate whether enteroendocrine
cells perceive linoleate differently when part of a complex, the ability of linoleate to increase production or secretion of the enteroendocrine satiety hormone, cholecystokinin, was measured. Cholecystokinin mRNA levels were different when linoleate was presented to the
cells alone or as part of a protein complex. In conclusion, understanding interactions between linoleate and BLG could help to formulate foods with targeted fatty
acid bioaccessibility and, therefore, aid in the development of food matrices with optimal bioactive efficacyS. Le Maux is currently supported by a Teagasc Walsh Fellowship and the Department of Agriculture, Fisheries and Food (FIRM project 08/RD/TMFRC/650). We also acknowledge funding from IRCSET-Ulysses Travel Grant
Level sets of functions and symmetry sets of smooth surface sections
We prove that the level sets of a real C^s function of two variables near a
non-degenerate critical point are of class C^[s/2] and apply this to the study
of planar sections of surfaces close to the singular section by the tangent
plane at hyperbolic points or elliptic points, and in particular at umbilic
points.
We also analyse the cases coming from degenerate critical points,
corresponding to elliptic cusps of Gauss on a surface, where the
differentiability is now reduced to C^[s/4].
However in all our applications to symmetry sets of families of plane curves,
we assume the C^infty smoothness.Comment: 15 pages, Latex, 6 grouped figures. The final version will appear in
Mathematics of Surfaces. Lecture Notes in Computer Science (2005
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