192 research outputs found
Healthy Sleep Leads to Improved Nutrition and Exercise in College Females
Diet, sleep quality, and exercise are important determinants of physical, mental, and emotional health. College students are particularly vulnerable to impaired health, as they experience multiple unique stressors associated with college life that impact their ability to engage in healthy sleep, diet, and exercise habits. Our results found that exercise significantly mediated the association between sleep quality and diet. Improved sleep habits may increase a young woman\u27s ability and desire to exercise, thus impacting her diet and nutrition. Findings suggest that clinicians can use a person\u27s motivation in any one domain, or multiple domains, to impact other health domains
Finite Temperature and Density Effect on Symmetry Breaking by Wilson Loops
A finite temperature and density effect of Wilson loop elements on non-simply
connected space is investigated in the model suggested by Hosotani. Using
one-loop calculations it is shown that the value of an "order parameter" does
not shift as the temperature grows. We find that finite density effect is of
much importance for restoration of symmetry.Comment: 11pages, no figur
Open Inflation With Scalar-tensor Gravity
The open inflation model recently proposed by Hawking and Turok is
investigated in scalar-tensor gravity context. If the dilaton-like field has no
potential, the instanton of our model is singular but has a finite action. The
Gibbons-Hawking surface term vanishes and hence, can not be used to make
nonzero. To obtain a successful open inflation one should introduce
other matter fields or a potential for the dilaton-like fields.Comment: 10 pages.1 figure. Some comments and references are improved. to be
published in PR
Conformal Couplings in Induced Gravity
It is found that the induced gravity with conformal couplings requires the
conformal invariance in both classical and quantum levels for consistency. This
is also true for the induced gravity with an extended conformal coupling
interacting with torsion.Comment: 10 pages, Revtex3.0, to appear in General Relativity and Gravitatio
Open Inflationary Universes in the Induced Gravity Theory
The induced gravity theory is a variant of Jordan--Brans--Dicke theory where
the `dilaton' field possesses a potential. It has the unusual feature that in
the presence of a false vacuum there is a {\em stable} static solution with the
dilaton field displaced from the minimum of its potential, giving perfect de
Sitter expansion. We demonstrate how this solution can be used to implement the
open inflationary universe scenario. The necessary second phase of inflation
after false vacuum decay by bubble nucleation is driven by the dilaton rolling
from the static point to the minimum of its potential. Because the static
solution is stable whilst the false vacuum persists, the required evolution
occurs for a wide range of initial conditions. As the exterior of the bubble is
perfect de Sitter space, there is no problem with fields rolling outside the
bubble, as in one of the related models considered by Linde and Mezhlumian, and
the expansion rates before and after tunnelling may be similar which prevents
problematic high-amplitude super-curvature modes from being generated. Once
normalized to the microwave background anisotropies seen by the COBE satellite,
the viable models form a one-parameter family for each possible .Comment: 7 pages RevTeX file with three figures incorporated (uses RevTeX and
epsf). Also available by e-mailing ARL, or by WWW at
http://star-www.maps.susx.ac.uk/papers/early_papers.htm
Scaling solutions in general non-minimal coupling theories
A class of generalized non-minimal coupling theories is investigated, in
search of scaling attractors able to provide an accelerated expansion at the
present time. Solutions are found in the strong coupling regime and when the
coupling function and the potential verify a simple relation. In such cases,
which include power law and exponential functions, the dynamics is independent
of the exact form of the coupling and the potential. The constraint from the
time variability of , however, limits the fraction of energy in the scalar
field to less than 4% of the total energy density, and excludes accelerated
solutions at the present.Comment: 10 pages, 3 figures, accepted for publication in Phys. Rev.
Conditions for Successful Extended Inflation
We investigate, in a model-independent way, the conditions required to obtain
a satisfactory model of extended inflation in which inflation is brought to an
end by a first-order phase transition. The constraints are that the correct
present strength of the gravitational coupling is obtained, that the present
theory of gravity is satisfactorily close to general relativity, that the
perturbation spectra from inflation are compatible with large scale structure
observations and that the bubble spectrum produced at the phase transition
doesn't conflict with the observed level of microwave background anisotropies.
We demonstrate that these constraints can be summarized in terms of the
behaviour in the conformally related Einstein frame, and can be compactly
illustrated graphically. We confirm the failure of existing models including
the original extended inflation model, and construct models, albeit rather
contrived ones, which satisfy all existing constraints.Comment: 8 pages RevTeX file with one figure incorporated (uses RevTeX and
epsf). Also available by e-mailing ARL, or by WWW at
http://star-www.maps.susx.ac.uk/papers/infcos_papers.html; Revised to include
extra references, results unchanged, to appear Phys Rev
Brans-Dicke wormholes in the Jordan and Einstein frames
We examine the possibility of static wormhole solutions in the vacuum
Brans-Dicke theory both in the original (Jordan) frame and in the conformally
rescaled (Einstein) frame. It turns out that, in the former frame, wormholes
exist only in a very narrow interval of the coupling parameter, viz.,
-3/2<omega<-4/3. It is shown that these wormholes are not traversable in
practice. In the latter frame, wormhole solutions do not exist at all unless
energy conditions are violated by hand.Comment: Minor errors corrected, uploaded for the benefit of the researcher
Classical Euclidean wormhole solutions in Palatini cosmology
We study the classical Euclidean wormholes in the context of extended
theories of gravity. With no loss of generality, we use the dynamical
equivalence between gravity and scalar-tensor theories to
construct a point-like Lagrangian in the flat FRW space time. We first show the
dynamical equivalence between Palatini gravity and the
Brans-Dicke theory with self-interacting potential, and then show the dynamical
equivalence between the Brans-Dicke theory with self-interacting potential and
the minimally coupled O'Hanlon theory. We show the existence of new Euclidean
wormhole solutions for this O'Hanlon theory and, for an special case, find out
the corresponding form of having wormhole solution. For small
values of the Ricci scalar, this is in agreement with the
wormhole solution obtained for higher order gravity theory .Comment: 11 page
- …