1,902,298 research outputs found
A Theory of the Casimir Effect for Compact Regions
We develop a mathematically precise framework for the Casimir effect. Our
working hypothesis, verified in the case of parallel plates, is that only the
regularization-independent Ramanujan sum of a given asymptotic series
contributes to the Casimir pressure. As an illustration, we treat two cases:
parallel plates, identifying a previous cutoff free version (by G. Scharf and
W. W.) as a special case, and the sphere.We finally discuss the open problem of
the Casimir force for the cube. We propose an Ansatz for the exterior force and
argue why it may provide the exact solution, as well as an explanation of the
repulsive sign of the force.Comment: version published, 23 page
Random sets and exact confidence regions
An important problem in statistics is the construction of confidence regions
for unknown parameters. In most cases, asymptotic distribution theory is used
to construct confidence regions, so any coverage probability claims only hold
approximately, for large samples. This paper describes a new approach, using
random sets, which allows users to construct exact confidence regions without
appeal to asymptotic theory. In particular, if the user-specified random set
satisfies a certain validity property, confidence regions obtained by
thresholding the induced data-dependent plausibility function are shown to have
the desired coverage probability.Comment: 14 pages, 2 figure
TOURISM AND ECONOMIC DEVELOPMENT IN MOUNTAIN REGIONS AN ECONOMIC ASSESSMENT
The paper gives a critical assessment of the theses of UNWTO that tourism is an effective means of developing whole regions especially difficult aeries such as mountain regions. Growth Pole Theory and Economic Base Theory are used as methodological base.Regional development, Growth Pole Theory, Economic Base Theory, Tourism
Heterotic String Field Theory
We construct the Neveu-Schwarz sector of heterotic string field theory using
the large Hilbert space of the superghosts and the multi-string products of
bosonic closed string field theory. No picture-changing operators are required
as in Wess-Zumino-Witten-like open superstring field theory. The action
exhibits a novel kind of nonpolynomiality: in addition to terms necessary to
cover missing regions of moduli spaces, new terms arise from the boundary of
the missing regions and its subspaces. We determine the action up to quintic
order and a subset of terms to all orders.Comment: 15 pages, no figures, LaTeX2e; v2: minor cosmetic change
Collective Correlations of Brodmann Areas fMRI Study with RMT-Denoising
We study collective behavior of Brodmann regions of human cerebral cortex
using functional Magnetic Resonance Imaging (fMRI) and Random Matrix Theory
(RMT). The raw fMRI data is mapped onto the cortex regions corresponding to the
Brodmann areas with the aid of the Talairach coordinates. Principal Component
Analysis (PCA) of the Pearson correlation matrix for 41 different Brodmann
regions is carried out to determine their collective activity in the idle state
and in the active state stimulated by tapping. The collective brain activity is
identified through the statistical analysis of the eigenvectors to the largest
eigenvalues of the Pearson correlation matrix. The leading eigenvectors have a
large participation ratio. This indicates that several Broadmann regions
collectively give rise to the brain activity associated with these
eigenvectors. We apply random matrix theory to interpret the underlying
multivariate data
The Black Hole Interior and a Curious Sum Rule
We analyze the Euclidean geometry near non-extremal NS5-branes in string
theory, including regions beyond the horizon and beyond the singularity of the
black brane. The various regions have an exact description in string theory, in
terms of cigar, trumpet and negative level minimal model conformal field
theories. We study the worldsheet elliptic genera of these three superconformal
theories, and show that their sum vanishes. We speculate on the significance of
this curious sum rule for black hole physics.Comment: 8 pages, 2 figure
The Shift of the Baryon Acoustic Oscillation Scale: A Simple Physical Picture
A shift of the baryon acoustic oscillation (BAO) scale to smaller values than
predicted by linear theory was observed in simulations. In this paper, we try
to provide an intuitive physical understanding of why this shift occurs,
explaining in more pedagogical detail earlier perturbation theory calculations.
We find that the shift is mainly due to the following physical effect. A
measurement of the BAO scale is more sensitive to regions with long wavelength
overdensities than underdensities, because (due to non-linear growth and bias)
these overdense regions contain larger fluctuations and more tracers and hence
contribute more to the total correlation function. In overdense regions the BAO
scale shrinks because such regions locally behave as positively curved closed
universes, and hence a smaller scale than predicted by linear theory is
measured in the total correlation function. Other effects which also contribute
to the shift are briefly discussed. We provide approximate analytic expressions
for the non-linear shift including a brief discussion of biased tracers and
explain why reconstruction should entirely reverse the shift. Our expressions
and findings are in agreement with simulation results, and confirm that
non-linear shifts should not be problematic for next-generation BAO
measurements.Comment: 10 pages, replaced with version accepted by Phys. Rev.
Baryon Configurations in the UV and IR Regions of Type 0 String Theory
The Type 0 string theory is considered as a dual model of a
non-supersymmetric gauge theory. A background geometry with N electric
D3-branes is calculated in UV/IR regions. In this paper, we study a D5-brane
around N D3-branes from the D5-brane world volume action as in the Type IIB
case, and we obtain some baryon configurations at UV/IR regions.Comment: 10 pages, 2 figures, harvmac+epsf, some errata correcte
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