3,795 research outputs found
Rotating Dilaton Black Holes
It is shown that an arbitrarily small amount of angular momentum can
qualitatively change the properties of extremal charged black holes coupled to
a dilaton. In addition, the gyromagnetic ratio of these black holes is computed
and an exact rotating black string solution is presented.Comment: 14 page
Race to the Paycheck: Merit Pay and Theories of Teacher Motivation
Recent reforms in teacher evaluation tie these evaluations to student performance as measured by test scores and merit pay has been offered as a way to reward high test scores and improve teacher performance. Thus, the federal Race to the Top program has led several states toward teacher evaluation instruments that incorporate outcome data in the form of student achievement. In most states, this is the first step in the plan to institute a pay for performance program for teachers, also known as merit pay. This paper analyzes the concept of merit pay through the lens of equity theory. Equity theory provides a framework to organize a workplace that is equitable, consistent, and free of self-interest. Readers are challenged to consider the implications of merit pay in light of equity theory and resultant issues for educational policy and practice
Colliding Plane Waves in Einstein-Maxwell-Dilaton Fields
Within the metric structure endowed with two orthogonal space-like Killing
vectors a class of solutions of the Einstein-Maxwell-Dilaton field equations is
presented. Two explicitly given sub-classes of solutions bear an interpretation
as colliding plane waves in the low-energy limit of the heterotic string
theory.Comment: 14 pages, LaTex; To appear in Phys. Rev.
Sports mega-events – three sites of contemporary political contestation
This article discusses the contemporary politics of sports mega-events, involving the Olympic Games and Fédération Internationale de Football Association (FIFA) Men’s Football World Cup Finals as well as other lower ‘order’ sports megas, taking two main forms: the promotional and the protest. There is a politics in, and a politics of, sports mega-events. The former focuses on the internal politics of the organizing bodies, such as the International Olympic Committee and FIFA. This form of politics has been written about elsewhere, and hence, there is no detailed discussion in this article about it. Instead this article offers a brief discussion of the range and number of sports mega-events since 2000, an assessment of the contemporary politics of sports mega-events, a focus on three main sites of political contestation – rights, legacy and labour, and finally, it offers conclusions about research into the politics of sports mega-events
Non-Singular Charged Black Hole Solution for Non-Linear Source
A non-singular exact black hole solution in General Relativity is presented.
The source is a non-linear electromagnetic field, which reduces to the Maxwell
theory for weak field. The solution corresponds to a charged black hole with
|q| \leq 2s_c m \approx 0.6 m, having metric, curvature invariants, and
electric field bounded everywhere.Comment: 3 pages, RevTe
Demonstration of the Complementarity of One- and Two-Photon Interference
The visibilities of second-order (single-photon) and fourth-order
(two-photon) interference have been observed in a Young's double-slit
experiment using light generated by spontaneous parametric down-conversion and
a photon-counting intensified CCD camera. Coherence and entanglement underlie
one-and two-photon interference, respectively. As the effective source size is
increased, coherence is diminished while entanglement is enhanced, so that the
visibility of single-photon interference decreases while that of two-photon
interference increases. This is the first experimental demonstration of the
complementarity between single- and two-photon interference (coherence and
entanglement) in the spatial domain.Comment: 21 pages, 7 figure
Radiation and shielding study for the International Ultraviolet Explorer
Technical advisory services to ensure integrity of parts and material exposed to energetic particle radiation for the IUE scientific instruments, spacecraft, and subsystems are provided. A significant potential for interference, degradation, or failure for unprotected or sensitive items was found. Vulnerable items were identified, and appropriate tests, changes, and shields were defined
Regular Black Hole in General Relativity Coupled to Nonlinear Electrodynamics
The first regular exact black hole solution in General Relativity is
presented. The source is a nonlinear electrodynamic field satisfying the weak
energy condition, which in the limit of weak field becomes the Maxwell field.
The solution corresponds to a charged black hole with |q| \leq 2 s_c m \approx
0.6 m, having the metric, the curvature invariants, and the electric field
regular everywhere.Comment: 5 pages, RevTex, 6 figure
- …