579 research outputs found
The Casimir Effect for Generalized Piston Geometries
In this paper we study the Casimir energy and force for generalized pistons
constructed from warped product manifolds of the type where
is an interval of the real line and is a smooth compact
Riemannian manifold either with or without boundary. The piston geometry is
obtained by dividing the warped product manifold into two regions separated by
the cross section positioned at . By exploiting zeta function
regularization techniques we provide formulas for the Casimir energy and force
involving the arbitrary warping function and base manifold .Comment: 16 pages, LaTeX. To appear in the proceedings of the Conference on
Quantum Field Theory Under the Influence of External Conditions (QFEXT11).
Benasque, Spain, September 18-24, 201
Relationship between blood remifentanil concentration and stress hormone levels during pneumoperitoneum in patients undergoing laparoscopic cholecystectomy
The effect of remifentanil on stress response to surgery is unclear. However, there are not clinical studies investigating the relationship between blood remifentanil concentrations and stress hormones. Therefore, the aim of the present study was to assess the association between blood remifentanil concentrations measured after pneumoperitoneum and cortisol (CORT) or prolactin (PRL) ratio (intraoperative/preoperative value), in patients undergoing laparoscopic cholecystectom
Kinematics in Matrix Gravity
We develop the kinematics in Matrix Gravity, which is a modified theory of
gravity obtained by a non-commutative deformation of General Relativity. In
this model the usual interpretation of gravity as Riemannian geometry is
replaced by a new kind of geometry, which is equivalent to a collection of
Finsler geometries with several Finsler metrics depending both on the position
and on the velocity. As a result the Riemannian geodesic flow is replaced by a
collection of Finsler flows. This naturally leads to a model in which a
particle is described by several mass parameters. If these mass parameters are
different then the equivalence principle is violated. In the non-relativistic
limit this also leads to corrections to the Newton's gravitational potential.
We find the first and second order corrections to the usual Riemannian geodesic
flow and evaluate the anomalous nongeodesic acceleration in a particular case
of static spherically symmetric background.Comment: 31 pages, no figures, discussion of Pioneer anomaly remove
Zeta Determinant for Laplace Operators on Riemann Caps
The goal of this paper is to compute the zeta function determinant for the
massive Laplacian on Riemann caps (or spherical suspensions). These manifolds
are defined as compact and boundaryless dimensional manifolds deformed by a
singular Riemannian structure. The deformed spheres, considered previously in
the literature, belong to this class. After presenting the geometry and
discussing the spectrum of the Laplacian, we illustrate a method to compute its
zeta regularized determinant. The special case of the deformed sphere is
recovered as a limit of our general formulas.Comment: 19 pages, 1 figur
Scalar Casimir effect between two concentric D-dimensional spheres
The Casimir energy for a massless scalar field between the closely spaced two
concentric D-dimensional (for D>3) spheres is calculated by using the mode
summation with contour integration in the complex plane of eigenfrequencies and
the generalized Abel-Plana formula for evenly spaced eigenfrequency at large
argument. The sign of the Casimir energy between closely spaced two concentric
D-dimensional spheres for a massless scalar field satisfying the Dirichlet
boundary conditions is strictly negative. The Casimir energy between D-1
dimensional surfaces close to each other is regarded as interesting both by
itself and as the key to describing of stability of the attractive Casimir
force. PACS number(s): 03.70.+k, 11.10.Kk, 11.10.Gh, 03.65.GeComment: 14 pages. arXiv admin note: substantial text overlap with
arXiv:1207.418
Experiences of cognitive stimulation therapy (CST) in Brazil: a qualitative study of people with dementia and their caregivers
Objectives:
There is a lack of investment in psychosocial treatments for people with dementia in Brazil. Cognitive Stimulation Therapy (CST) is a group-based intervention that has shown to have benefits on activities of daily living and mood for people with dementia in Brazil. This study aims to explore the experiences and perceived changes following CST groups.
Methods:
Individual interviews were conducted with the participants of the group (n = 12) and their caregivers (n = 11). Framework analysis was used to inspect the data.
Results:
Two main themes have emerged: ‘Personal benefits of being part of the group’, containing two subthemes: ‘Benefits for caregivers’ and ‘Benefits for person with dementia’ and ‘Day-to-day changes’, containing seven subthemes; ‘Memory’, Sociability’, ‘Language’, ‘Mood’, ‘Orientation’, ‘Everyday activities’ and ‘Behavioural and psychological symptoms’.
Conclusion:
Results suggest that CST groups led to perceived personal benefits for the people with dementia and caregivers and that there are perceived changes for the participants of the groups
New Developments in the Spectral Asymptotics of Quantum Gravity
A vanishing one-loop wave function of the Universe in the limit of small
three-geometry is found, on imposing diffeomorphism-invariant boundary
conditions on the Euclidean 4-ball in the de Donder gauge. This result suggests
a quantum avoidance of the cosmological singularity driven by full
diffeomorphism invariance of the boundary-value problem for one-loop quantum
theory. All of this is made possible by a peculiar spectral cancellation on the
Euclidean 4-ball, here derived and discussed.Comment: 7 pages, latex file. Paper prepared for the Conference "QFEXT05:
Quantum Field Theory Under the Influence of External Conditions", Barcelona,
September 5 - September 9, 2005. In the final version, the presentation has
been further improved, and yet other References have been adde
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