79,704 research outputs found
Next Day Subjective and Objective Recovery Indices Following Acute Low and High Training Loads in Academy Rugby Union Players
The aim of this study was to determine the sensitivity of selected subjective and objective monitoring assessments in detecting changes in group and individual responses to low and high load bouts of high intensity intermittent exercise. In a counterbalanced crossover design, Thirteen Academy Rugby Union players (mean ± SD: age: 18 ± 1 years) performed a low load (15 min) and a high load (90 min) bout of high intensity intermittent exercise (Loughborough Intermittent Shuttle Test) one week apart. Monitoring assessments were performed immediately prior to and 20 h following each trial. Subjective self-report Well-being Questionnaire (WQ) items showed small to large deteriorations following the high load compared to low load (d = 0.4–1.5, p = 0.03–0.57). A very large increase in resting HR (HRrest) (d = 2.1, p = 0.02), moderate decrease in heart rate variability (HRV) indices (d = 0.7, p = 0.04 and d = 0.7, p = 0.01 for the natural logarithm of the standard deviation of R-R intervals (ln SDNN) and the root square of the mean squared differences of successive R-R intervals (rMSSD), respectively) and no change in countermovement jump (d = 0.0, p = 0.97) were evident following the high load compared to low load. Individual WQ responses revealed 7/9, 7/9, 6/9, 6/9, 5/9, 3/9 and 1/9 participants reported deteriorations in recovery, sleep quality, motivation, muscle soreness, fatigue, stress and appetite, respectively, following the high load compared to low load. Individual analysis indicated a negative response following the high load compared to low load in HRrest, ln SDNN and ln rMSSD for 4/6, 2/6 and 1/6 participants, respectively. Selected WQ items detected group and individual responses to high load and low load highlighting their potential utility. However, objective assessments lacked the sensitivity to detect small individual changes
A New Model of Agegraphic Dark Energy
In this note, we propose a new model of agegraphic dark energy based on the
K\'{a}rolyh\'{a}zy relation, where the time scale is chosen to be the conformal
time of the Friedmann-Robertson-Walker (FRW) universe. We find that in
the radiation-dominated epoch, the equation-of-state parameter of the new
agegraphic dark energy whereas ; in the
matter-dominated epoch, whereas ; eventually, the
new agegraphic dark energy dominates; in the late time when
, and the new agegraphic dark energy mimics a cosmological
constant. In every stage, all things are consistent. The confusion in the
original agegraphic dark energy model proposed in arXiv:0707.4049 disappears in
this new model. Furthermore, is naturally satisfied in both
radiation-dominated and matter-dominated epochs where . In addition, we
further extend the new agegraphic dark energy model by including the
interaction between the new agegraphic dark energy and background matter. In
this case, we find that can cross the phantom divide.Comment: 8 pages, revtex4; v2: Phys. Lett. B in press; v3: published versio
Constraining the Dark Universe
We combine complementary datasets to constrain dark energy. Using standard
Big Bang Nucleosynthesis and the observed abundances of primordial nuclides to
put constraints on at temperatures near , we find the
strong constraint at c.l.. Under the
assumption of flatness, using results from Cosmic Microwave Background (CMB)
anisotropy measurements, high redshift supernovae (SN-Ia) observations and data
from local cluster abundances we put a new constraint on the equation of state
parameter at 68% c.l..Comment: 5 pages, 3 figures, new reference added. To appear in the proceedings
of TAUP 2001 (7th international workshop on Topics in Astroparticle and
Underground Physics), Sep 2001, Laboratori Nazionali del Gran Sasso, Assergi,
Ital
Omega risk model with tax
In this paper we study the Omega risk model with surplus-dependent tax
payments in a time-homogeneous diffusion setting. The new model incorporates
practical features from both the Omega risk model(Albrecher and Gerber and Shiu
(2011)) and the risk model with tax(Albrecher and Hipp (2007)). We explicitly
characterize the Laplace transform of the occupation time of an Azema-Yor
process(e.g. a process refracted by functionals of its running maximum) below a
constant level until the first hitting time of another Azema-Yor process or
until an independent exponential time. This result unifies and extends recent
literature(Li and Zhou (2013) and Zhang (2014)) incorporating some of their
results as special cases. We explicitly characterize the Laplace transform of
the time of bankruptcy in the Omega risk model with tax and discuss an
extension to integral functionals. Finally we present examples using a Brownian
motion with drift
Pimsner algebras and Gysin sequences from principal circle actions
A self Morita equivalence over an algebra B, given by a B-bimodule E, is
thought of as a line bundle over B. The corresponding Pimsner algebra O_E is
then the total space algebra of a noncommutative principal circle bundle over
B. A natural Gysin-like sequence relates the KK-theories of O_E and of B.
Interesting examples come from O_E a quantum lens space over B a quantum
weighted projective line (with arbitrary weights). The KK-theory of these
spaces is explicitly computed and natural generators are exhibited.Comment: 29 pages. v2: Scientific content unchanged. Exposition improved.
Added references. To appear in the JNc
Regulating the infrared by mode matching: A massless scalar in expanding spaces with constant deceleration
In this paper we consider a massless scalar field, with a possible coupling
to the Ricci scalar in a dimensional FLRW spacetime with a constant
deceleration parameter , . Correlation
functions for the Bunch-Davies vacuum of such a theory have long been known to
be infrared divergent for a wide range of values of . We resolve
these divergences by explicitly matching the spacetime under consideration to a
spacetime without infrared divergencies. Such a procedure ensures that all
correlation functions with respect to the vacuum in the spacetime of interest
are infrared finite. In this newly defined vacuum we construct the coincidence
limit of the propagator and as an example calculate the expectation value of
the stress energy tensor. We find that this approach gives both in the
ultraviolet and in the infrared satisfactory results. Moreover, we find that,
unless the effective mass due to the coupling to the Ricci scalar is
negative, quantum contributions to the energy density always dilute away
faster, or just as fast, as the background energy density. Therefore, quantum
backreaction is insignificant at the one loop order, unless is
negative. Finally we compare this approach with known results where the
infrared is regulated by placing the Universe in a finite box. In an
accelerating universe, the results are qualitatively the same, provided one
identifies the size of the Universe with the physical Hubble radius at the time
of the matching. In a decelerating universe however, the two schemes give
different late time behavior for the quantum stress energy tensor. This happens
because in this case the length scale at which one regulates the infrared
becomes sub-Hubble at late times.Comment: 55 pages, 6 figure
Quantum W-algebras and Elliptic Algebras
We define quantum W-algebras generalizing the results of Reshetikhin and the
second author, and Shiraishi-Kubo-Awata-Odake. The quantum W-algebra associated
to sl_N is an associative algebra depending on two parameters. For special
values of parameters it becomes the ordinary W-algebra of sl_N, or the
q-deformed classical W-algebra of sl_N. We construct free field realizations of
the quantum W-algebras and the screening currents. We also point out some
interesting elliptic structures arising in these algebras. In particular, we
show that the screening currents satisfy elliptic analogues of the Drinfeld
relations in U_q(n^).Comment: 26 pages, AMSLATE
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