4,962 research outputs found
Barker Central School District and Barker Central School Support Staff
In the matter of the fact-finding between the Barker Central School District, employer, and the Barker Central School Support Staff, union. PERB case no. M2009-035
Genesee, County of and The Civil Service Employees Association
In the Matter of the Fact-Finding between The County of Genesee, New York and The Civil Service Employees Association. PERB Case No. M2008-249. Michael S. Lewandowski, Fact Finder
Extremal Isolated Horizons: A Local Uniqueness Theorem
We derive all the axi-symmetric, vacuum and electrovac extremal isolated
horizons. It turns out that for every horizon in this class, the induced metric
tensor, the rotation 1-form potential and the pullback of the electromagnetic
field necessarily coincide with those induced by the monopolar, extremal
Kerr-Newman solution on the event horizon. We also discuss the general case of
a symmetric, extremal isolated horizon. In particular, we analyze the case of a
two-dimensional symmetry group generated by two null vector fields. Its
relevance to the classification of all the symmetric isolated horizons,
including the non-extremal once, is explained.Comment: 22 pages, page size changed, typos and equations (142), (143a)
corrected, PACS number adde
Access to undergraduate research experiences at a large research university
The American Physical Society recently released a statement calling on all
university physics departments to provide or facilitate access to research
experiences for all undergraduate students. In response, we investigated the
current status of access to undergraduate research at University of Colorado
Boulder (CU), a large research institution where the number of undergraduate
physics majors outnumber faculty by roughly ten to one. We created and
administered two surveys within CU's Physics Department: one probed
undergraduate students' familiarity with, and participation in, research; the
other probed faculty members' experiences as research mentors to
undergraduates. We describe the development of these instruments, our results,
and our corresponding evidence-based recommendations for improving local access
to undergraduate research experiences. Reflecting on our work, we make several
connections to an institutional change framework and note how other
universities and colleges might adapt our process.Comment: 4 pages, 3 figures, 1 table; Submitted to 2015 PERC Proceeding
Quantum isolated horizons and black hole entropy
We give a short introduction to the approaches currently used to describe
black holes in loop quantum gravity. We will concentrate on the classical
issues related to the modeling of black holes as isolated horizons, give a
short discussion of their canonical quantization by using loop quantum gravity
techniques, and a description of the combinatorial methods necessary to solve
the counting problems involved in the computation of the entropy.Comment: 28 pages in A4 format. Contribution to the Proceedings of the 3rd
Quantum Geometry and Quantum Gravity School in Zakopane (2011
Completeness of Wilson loop functionals on the moduli space of and -connections
The structure of the moduli spaces \M := \A/\G of (all, not just flat)
and connections on a n-manifold is analysed. For any
topology on the corresponding spaces \A of all connections which satisfies
the weak requirement of compatibility with the affine structure of \A, the
moduli space \M is shown to be non-Hausdorff. It is then shown that the
Wilson loop functionals --i.e., the traces of holonomies of connections around
closed loops-- are complete in the sense that they suffice to separate all
separable points of \M. The methods are general enough to allow the
underlying n-manifold to be topologically non-trivial and for connections to be
defined on non-trivial bundles. The results have implications for canonical
quantum general relativity in 4 and 3 dimensions.Comment: Plain TeX, 7 pages, SU-GP-93/4-
Spacetimes foliated by Killing horizons
It seems to be expected, that a horizon of a quasi-local type, like a Killing
or an isolated horizon, by analogy with a globally defined event horizon,
should be unique in some open neighborhood in the spacetime, provided the
vacuum Einstein or the Einstein-Maxwell equations are satisfied. The aim of our
paper is to verify whether that intuition is correct. If one can extend a so
called Kundt metric, in such a way that its null, shear-free surfaces have
spherical spacetime sections, the resulting spacetime is foliated by so called
non-expanding horizons. The obstacle is Kundt's constraint induced at the
surfaces by the Einstein or the Einstein-Maxwell equations, and the requirement
that a solution be globally defined on the sphere. We derived a transformation
(reflection) that creates a solution to Kundt's constraint out of data defining
an extremal isolated horizon. Using that transformation, we derived a class of
exact solutions to the Einstein or Einstein-Maxwell equations of very special
properties. Each spacetime we construct is foliated by a family of the Killing
horizons. Moreover, it admits another, transversal Killing horizon. The
intrinsic and extrinsic geometry of the transversal Killing horizon coincides
with the one defined on the event horizon of the extremal Kerr-Newman solution.
However, the Killing horizon in our example admits yet another Killing vector
tangent to and null at it. The geometries of the leaves are given by the
reflection.Comment: LaTeX 2e, 13 page
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