531 research outputs found
Experiences of Burnout Among Adolescent Female Gymnasts: Three Case Studies
Within the current study, the process of adolescent burnout is considered in relation to perceived contributors, symptoms, consequences, and subsequently, effective and ineffective coping strategies. Through case studies, the researchers sought the burnout experiences of three competitive female gymnasts. Participants were selected based on scores obtained from Raedeke and Smith’s (2001) Athlete Burnout Questionnaire. To gain a comprehensive understanding of the process, athlete data were considered in tandem with interviews from at least one parent and one coach. Transcribed data were segmented into meaning units, coded into a hierarchy of themes and verified by each respondent. Despite common trends among the participants, differences were also found in relation to symptoms, contributors, and the progression of the condition. Implications are provided for the athlete/parent/coach triad and also for sport psychologists
Bounded and unitary elements in pro-C^*-algebras
A pro-C^*-algebra is a (projective) limit of C^*-algebras in the category of
topological *-algebras. From the perspective of non-commutative geometry,
pro-C^*-algebras can be seen as non-commutative k-spaces. An element of a
pro-C^*-algebra is bounded if there is a uniform bound for the norm of its
images under any continuous *-homomorphism into a C^*-algebra. The *-subalgebra
consisting of the bounded elements turns out to be a C^*-algebra. In this
paper, we investigate pro-C^*-algebras from a categorical point of view. We
study the functor (-)_b that assigns to a pro-C^*-algebra the C^*-algebra of
its bounded elements, which is the dual of the Stone-\v{C}ech-compactification.
We show that (-)_b is a coreflector, and it preserves exact sequences. A
generalization of the Gelfand-duality for commutative unital pro-C^*-algebras
is also presented.Comment: v2 (accepted
Cryoballoon Ablation for Atrial Fibrillation
Focal point-by-point radiofrequency catheter ablation has shown considerable success in the treatment of paroxysmal atrial fibrillation. However, it is not without limitations. Recent clinical and preclinical studies have demonstrated that cryothermal ablation using a balloon catheter (Artic Front©, Medtronic CryoCath LP) provides an effective alternative strategy to treating atrial fibrillation. The objective of this article is to review efficacy and safety data surrounding cryoballoon ablation for paroxysmal and persistent atrial fibrillation. In addition, a practical step-by-step approach to cryoballoon ablation is presented, while highlighting relevant literature regarding: 1) the rationale for adjunctive imaging, 2) selection of an appropriate cryoballoon size, 3) predictors of efficacy, 4) advanced trouble-shooting techniques, and 5) strategies to reduce procedural complications, such as phrenic nerve palsy
Pre-torsors and Galois comodules over mixed distributive laws
We study comodule functors for comonads arising from mixed distributive laws.
Their Galois property is reformulated in terms of a (so-called) regular arrow
in Street's bicategory of comonads. Between categories possessing equalizers,
we introduce the notion of a regular adjunction. An equivalence is proven
between the category of pre-torsors over two regular adjunctions
and on one hand, and the category of regular comonad arrows
from some equalizer preserving comonad to on
the other. This generalizes a known relationship between pre-torsors over equal
commutative rings and Galois objects of coalgebras.Developing a bi-Galois
theory of comonads, we show that a pre-torsor over regular adjunctions
determines also a second (equalizer preserving) comonad and a
co-regular comonad arrow from to , such that the
comodule categories of and are equivalent.Comment: 34 pages LaTeX file. v2: a few typos correcte
Fractal Analysis of Protein Potential Energy Landscapes
The fractal properties of the total potential energy V as a function of time
t are studied for a number of systems, including realistic models of proteins
(PPT, BPTI and myoglobin). The fractal dimension of V(t), characterized by the
exponent \gamma, is almost independent of temperature and increases with time,
more slowly the larger the protein. Perhaps the most striking observation of
this study is the apparent universality of the fractal dimension, which depends
only weakly on the type of molecular system. We explain this behavior by
assuming that fractality is caused by a self-generated dynamical noise, a
consequence of intermode coupling due to anharmonicity. Global topological
features of the potential energy landscape are found to have little effect on
the observed fractal behavior.Comment: 17 pages, single spaced, including 12 figure
Dynamical chaos and power spectra in toy models of heteropolymers and proteins
The dynamical chaos in Lennard-Jones toy models of heteropolymers is studied
by molecular dynamics simulations. It is shown that two nearby trajectories
quickly diverge from each other if the heteropolymer corresponds to a random
sequence. For good folders, on the other hand, two nearby trajectories may
initially move apart but eventually they come together. Thus good folders are
intrinsically non-chaotic. A choice of a distance of the initial conformation
from the native state affects the way in which a separation between the twin
trajectories behaves in time. This observation allows one to determine the size
of a folding funnel in good folders. We study the energy landscapes of the toy
models by determining the power spectra and fractal characteristics of the
dependence of the potential energy on time. For good folders, folding and
unfolding trajectories have distinctly different correlated behaviors at low
frequencies.Comment: 8 pages, 9 EPS figures, Phys. Rev. E (in press
Fourier analysis of 2-point Hermite interpolatory subdivision schemes
Two subdivision schemes with Hermite data on Z are studied. These schemes use 2 or 7 parameters respectively depending on whether Hermite data involve only first derivatives or include second derivatives. For a large region in the parameters space, the schemes are C1 or C2 convergent or at least are convergent on the space of Schwartz distributions. The Fourier transform of any interpolating function can be computed through products of matrices of order 2 or 3. The Fourier transform is related to a specific system of functional equations whose analytic solution is unique except for a multiplicative constant. The main arguments for these results come from Paley-Wiener-Schwartz theorem on the characterization of the Fourier transforms of distributions with compact support and a theorem of Artzrouni about convergent products of matrices
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