346 research outputs found
Resurrection from a Death Sentence: Why Capital Sentences Should be Commuted upon the Occasion of an Authentic Ethical Transformation
Resurrection from a Death Sentence: Why Capital Sentences Should be Commuted upon the Occasion of an Authentic Ethical Transformation
Algorithmic Randomness and Capacity of Closed Sets
We investigate the connection between measure, capacity and algorithmic
randomness for the space of closed sets. For any computable measure m, a
computable capacity T may be defined by letting T(Q) be the measure of the
family of closed sets K which have nonempty intersection with Q. We prove an
effective version of Choquet's capacity theorem by showing that every
computable capacity may be obtained from a computable measure in this way. We
establish conditions on the measure m that characterize when the capacity of an
m-random closed set equals zero. This includes new results in classical
probability theory as well as results for algorithmic randomness. For certain
computable measures, we construct effectively closed sets with positive
capacity and with Lebesgue measure zero. We show that for computable measures,
a real q is upper semi-computable if and only if there is an effectively closed
set with capacity q
LAGEOS geodetic analysis-SL7.1
Laser ranging measurements to the LAGEOS satellite from 1976 through 1989 are related via geodetic and orbital theories to a variety of geodetic and geodynamic parameters. The SL7.1 analyses are explained of this data set including the estimation process for geodetic parameters such as Earth's gravitational constant (GM), those describing the Earth's elasticity properties (Love numbers), and the temporally varying geodetic parameters such as Earth's orientation (polar motion and Delta UT1) and tracking site horizontal tectonic motions. Descriptions of the reference systems, tectonic models, and adopted geodetic constants are provided; these are the framework within which the SL7.1 solution takes place. Estimates of temporal variations in non-conservative force parameters are included in these SL7.1 analyses as well as parameters describing the orbital states at monthly epochs. This information is useful in further refining models used to describe close-Earth satellite behavior. Estimates of intersite motions and individual tracking site motions computed through the network adjustment scheme are given. Tabulations of tracking site eccentricities, data summaries, estimated monthly orbital and force model parameters, polar motion, Earth rotation, and tracking station coordinate results are also provided
D-instantons and Closed String Tachyons in Misner Space
We investigate closed string tachyon condensation in Misner space, a toy
model for big bang universe. In Misner space, we are able to condense tachyonic
modes of closed strings in the twisted sectors, which is supposed to remove the
big bang singularity. In order to examine this, we utilize D-instanton as a
probe. First, we study general properties of D-instanton by constructing
boundary state and effective action. Then, resorting to these, we are able to
show that tachyon condensation actually deforms the geometry such that the
singularity becomes milder.Comment: 24 pages, 1 figure, minor change
Hypermoduli Stabilization, Flux Attractors, and Generating Functions
We study stabilization of hypermoduli with emphasis on the effects of
generalized fluxes. We find a class of no-scale vacua described by ISD
conditions even in the presence of geometric flux. The associated flux
attractor equations can be integrated by a generating function with the
property that the hypermoduli are determined by a simple extremization
principle. We work out several orbifold examples where all vector moduli and
many hypermoduli are stabilized, with VEVs given explicitly in terms of fluxes.Comment: 45 pages, no figures; Version submitted to JHE
Negotiating the horizon - living Christianity in Melanesia
[W]here is the horizon that separates the foreign and the indigenous, and who can successfully claim to make foreign powers indigenous or to ‘make the global local’? The boundaries of the foreign and the indigenous are fluid and contested—especially between genders and generations. Moreover, such contests are configured in part by the differences between localities (Jolly 2005, p. 138).Alison Dundo
A Calculable Toy Model of the Landscape
Motivated by recent discussions of the string-theory landscape, we propose
field-theoretic realizations of models with large numbers of vacua. These
models contain multiple U(1) gauge groups, and can be interpreted as
deconstructed versions of higher-dimensional gauge theory models with fluxes in
the compact space. We find that the vacuum structure of these models is very
rich, defined by parameter-space regions with different classes of stable vacua
separated by boundaries. This allows us to explicitly calculate physical
quantities such as the supersymmetry-breaking scale, the presence or absence of
R-symmetries, and probabilities of stable versus unstable vacua. Furthermore,
we find that this landscape picture evolves with energy, allowing vacua to
undergo phase transitions as they cross the boundaries between different
regions in the landscape. We also demonstrate that supergravity effects are
crucial in order to stabilize most of these vacua, and in order to allow the
possibility of cancelling the cosmological constant.Comment: 49 pages, LaTeX, 13 figures, references adde
Lectures on Nongeometric Flux Compactifications
These notes present a pedagogical review of nongeometric flux
compactifications. We begin by reviewing well-known geometric flux
compactifications in Type II string theory, and argue that one must include
nongeometric "fluxes" in order to have a superpotential which is invariant
under T-duality. Additionally, we discuss some elementary aspects of the
worldsheet description of nongeometric backgrounds. This review is based on
lectures given at the 2007 RTN Winter School at CERN.Comment: 31 pages, JHEP
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