16,030 research outputs found
Chiral Supersymmetric Gepner Model Orientifolds
We explicitly construct A-type orientifolds of supersymmetric Gepner models.
In order to reduce the tadpole cancellation conditions to a treatable number we
explicitly work out the generic form of the one-loop Klein bottle, annulus and
Moebius strip amplitudes for simple current extensions of Gepner models.
Equipped with these formulas, we discuss two examples in detail to provide
evidence that in this setting certain features of the MSSM like unitary gauge
groups with large enough rank, chirality and family replication can be
achieved.Comment: 37 pages, TeX (harvmac), minor changes, typos corrected, to appear in
JHE
Topic Maps as a Virtual Observatory tool
One major component of the VO will be catalogs measuring gigabytes and
terrabytes if not more. Some mechanism like XML will be used for structuring
the information. However, such mechanisms are not good for information
retrieval on their own. For retrieval we use queries. Topic Maps that have
started becoming popular recently are excellent for segregating information
that results from a query. A Topic Map is a structured network of hyperlinks
above an information pool. Different Topic Maps can form different layers above
the same information pool and provide us with different views of it. This
facilitates in being able to ask exact questions, aiding us in looking for gold
needles in the proverbial haystack. Here we discuss the specifics of what Topic
Maps are and how they can be implemented within the VO framework.
URL: http://www.astro.caltech.edu/~aam/science/topicmaps/Comment: 11 pages, 5 eps figures, to appear in SPIE Annual Meeting 2001
proceedings (Astronomical Data Analysis), uses spie.st
The SDSS Galaxy Angular Two-Point Correlation Function
We present the galaxy two-point angular correlation function for galaxies
selected from the seventh data release of the Sloan Digital Sky Survey. The
galaxy sample was selected with -band apparent magnitudes between 17 and 21;
and we measure the correlation function for the full sample as well as for the
four magnitude ranges: 17-18, 18-19, 19-20, and 20-21. We update the flag
criteria to select a clean galaxy catalog and detail specific tests that we
perform to characterize systematic effects, including the effects of seeing,
Galactic extinction, and the overall survey uniformity. Notably, we find that
optimally we can use observed regions with seeing < 1\farcs5, and -band
extinction < 0.13 magnitudes, smaller than previously published results.
Furthermore, we confirm that the uniformity of the SDSS photometry is minimally
affected by the stripe geometry. We find that, overall, the two-point angular
correlation function can be described by a power law, with , over the range
0\fdg005--10\degr. We also find similar relationships for the four
magnitude subsamples, but the amplitude within the same angular interval for
the four subsamples is found to decrease with fainter magnitudes, in agreement
with previous results. We find that the systematic signals are well below the
galaxy angular correlation function for angles less than approximately
5\degr, which limits the modeling of galaxy angular correlations on larger
scales. Finally, we present our custom, highly parallelized two-point
correlation code that we used in this analysis.Comment: 22 pages, 17 figures, accepted by MNRA
Supporting disabled parents' involvement in their children's education. Good practice guidance for schools
In this guidance you will find the voices of a range of disabled parents describing how good practice in schools has helped them to be involved in their children's education. The guidance is based on the findings of a research project. It is intended for people working in schools, especially heads and teachers seeking to improve parental participation and inclusion. Education policy makers and Inspectorates may find it helpful for informing their reviews of policy and practice. It may also be of interest to disabled parents and the disability voluntary sector. The document contains information about current UK policies on parental involvement and describes the research project which investigated the perceptions of disabled parents. It looks at five different aspects of parental involvement, giving examples of good practice and highlighting suggestions as these emerged from the research project. Key points are summarised in the conclusion, while the appendices include useful resources and contacts
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