6,222 research outputs found
Dynamical Topology Change in M Theory
We study topology change in M theory compactifications on Calabi-Yau
three-folds in the presence of G flux (the four form field strength). In
particular, we discuss vacuum solutions in strongly coupled heterotic string
theory in which the topology change is inevitable within a single spacetime
background. For rather generic choices of initial conditions, the field
equations drive the Kahler moduli outside the classical moduli space of a
Calabi-Yau manifold. Consistency of the solution suggests that degenerate flop
curves - just as wrapped M theory fivebranes - carry magnetic charges under the
four form field strength.Comment: 21 pages, LaTeX, 2 figures (eps
An Analysis of Parent Voting Patterns in Rural School Bond Elections
School officials should remember that attempts to increase affirmative voter turnout are in actuality attempts to change the habits of voters
Inflation as a Probe of Short Distance Physics
We show that a string-inspired Planck scale modification of general
relativity can have observable cosmological effects. Specifically, we present a
complete analysis of the inflationary perturbation spectrum produced by a
phenomenological Lagrangian that has a standard form on large scales but
incorporates a string-inspired short distance cutoff, and find a deviation from
the standard result. We use the de Sitter calculation as the basis of a
qualitative analysis of other inflationary backgrounds, arguing that in these
cases the cutoff could have a more pronounced effect, changing the shape of the
spectrum. Moreover, the computational approach developed here can be used to
provide unambiguous calculations of the perturbation spectrum in other
heuristic models that modify trans-Planckian physics and thereby determine
their impact on the inflationary perturbation spectrum. Finally, we argue that
this model may provide an exception to constraints, recently proposed by Tanaka
and Starobinsky, on the ability of Planck-scale physics to modify the
cosmological spectrum.Comment: revtex, 8 pages, eps figures included, references adde
State of the World's Fathers: 2015
Fathers' involvement in their children's lives has been linked to higher cognitive development and school achievement, better mental health for boys and girls, and lower rates of delinquency in sons. Studies in multiple countries have shown that fathers' interaction is important for the development of empathy and social skills in sons and daughters.The SOWF report states that to achieve full gender equality and maximum wellbeing for children, we must move beyond rigid, limiting definitions of fatherhood and motherhood. This is not just a question of encouraging men to be nurturing and caring but rather an issue of social and economic justice. The report states that changes are needed in policies, in systems and institutions, among service providers, within programming and within data collection and analysis efforts. A lack of supportive policies such as paternity leave for new fathers helps cause an imbalance between mothers and fathers. This causes women to miss out on opportunities for work and income, children to miss out on having an involved father, and men to miss out on the positive benefits of involved fatherhood
Efficient Contextual Measures for Classification of Multispectral Image Data
The most common method for labeling multispectral image data classifies each pixel entirely on the basis of its own spectral signature. Such a method neither utilizes contextual information in the image nor does it incorporate secondary information related to the scene. This exclusion is generally due to the poor cost/performance efficiency of most contextual algorithms and a lack of knowledge concerning how to relate variables from different sources. In this research, several efficient spatial context measures are developed from different structural models for four-nearest-neighbor neighborhoods. Most of these measures rely on simple manipulations of label probabilities generated by a noncontextual classifier. They are efficient computationally and are effective in improving classification accuracy over the noncontextual result. Among other schemata, the measures include: average label probabilities in a neighborhood; label probabilities; combined as a function of a metric in the label probability space; and context through semantic constraints within a Bayesian framework. In addition, an efficient implementation of a contextual classifier based on compound decision theory is developed through a simplification of the structure of the contextual prior probability^ No accuracy is lost through the simplification, but computational speed is increased 15-fold. Finally, a procedure to combine label probabilities from independent data sources is proposed. A mechanism for combining the label probabilities from each of the sources as a function of their independent classification accuracies is created and evaluated
Observing the Geometry of Warped Compactification via Cosmic Inflation
Using DBI inflation as an example, we demonstrate that the detailed geometry
of warped compactification can leave an imprint on the cosmic microwave
background (CMB). We compute CMB observables for DBI inflation in a generic
class of warped throats and find that the results (such as the sign of the tilt
of the scalar perturbations and its running) depend sensitively on the precise
shape of the warp factor. In particular, we analyze the warped deformed
conifold and find that the results can differ from those of other warped
geometries, even when these geometries approximate well the exact metric of the
warped deformed conifold.Comment: 4 pages, 3 figures. v2: References and clarifications adde
On the Hagedorn Behaviour of PP-wave Strings and N=4 SYM Theory at Finite R-Charge Density
We discuss the high temperature behaviour of IIB strings in the maximally
symmetric plane wave background, and show that there is a Hagedorn temperature.
We discuss the map between strings in the pp-wave background and the dual
superconformal field theory in the thermal domain. The Hagedorn bound describes
a curve in the R-charge chemical potential versus temperature phase diagram of
the dual Yang-Mills theory and the theory manifestly exists on both sides.
Using a recent observation of Brower, Lowe, and Tan, we update our earlier
calculation to reflect that the pp-wave string exists on both sides of the
Hagedorn bound as well.Comment: 23 pages, LaTeX, 1 figure; v2 minor corrections and clarifications,
references added; v3 nature of the Hagedorn transition updated, version
published in NP
Richard Strauss: The Two Concertos for Horn and Orchestra
A study of Richard Strauss\u27 two concertos for horn
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