365 research outputs found
Moral education in public schools and the church: building bridges
In recent decades, public schools have been challenged to integrate student character development with academics. This challenge requires a reallocation of school resources that have been previously devoted only to academics. However, with current academic standards demanding more resources than many schools can supply, incorporating character development becomes extremely difficult. The goal of this paper is to open the door for discussion regarding the possibility that public schools and local churches can have a mutually beneficial relationship for the purpose of enhancing student character development to promote both academic and spiritual excellence. To establish background about the school's role in moral development, the church's relationship to public schools, and the key components of effective character education, a review of literature was conducted. An analysis of character frameworks revealed the alignment of key character components as identified by both public schools and the church. These findings show that a reciprocal relationship is possible, therefore preserving valuable school resources such that academic excellence can be maintained as a priority.B.S. (Bachelor of Science
Bondian frames to couple matter with radiation
A study is presented for the non linear evolution of a self gravitating
distribution of matter coupled to a massless scalar field. The characteristic
formulation for numerical relativity is used to follow the evolution by a
sequence of light cones open to the future. Bondian frames are used to endow
physical meaning to the matter variables and to the massless scalar field.
Asymptotic approaches to the origin and to infinity are achieved; at the
boundary surface interior and exterior solutions are matched guaranteeing the
Darmois--Lichnerowicz conditions. To show how the scheme works some numerical
models are discussed. We exemplify evolving scalar waves on the following fixed
backgrounds: A) an atmosphere between the boundary surface of an incompressible
mixtured fluid and infinity; B) a polytropic distribution matched to a
Schwarzschild exterior; C) a Schwarzschild- Schwarzschild spacetime. The
conservation of energy, the Newman--Penrose constant preservation and other
expected features are observed.Comment: 20 pages, 6 figures; to appear in General Relativity and Gravitatio
High School Exit Examinations: When Do Learning Effects Generalize?
This paper reviews international and domestic evidence on the effects of three types of high school exit exam systems: voluntary curriculum-based external exit exams, universal curriculum-based external exit exam systems and minimum competency tests that must be passed to receive a regular high school diploma. The nations and provinces that use Universal CBEEES (and typically teacher grades as well) to signal student achievement have significantly higher achievement levels and smaller differentials by family background than otherwise comparable jurisdictions that base high stakes decisions on voluntary college admissions tests and/or teacher grades. The introduction of Universal CBEEES in New York and North Carolina during the 1990s was associated with large increases in math achievement on NAEP tests. Research on MCTs and high school accountability tests is less conclusive because these systems are new and have only been implemented in one country. Cross-section studies using a comprehensive set of controls for family background have not found that students in MCT states score higher on audit tests like the NAEP that carry no stakes for the test taker. The analysis reported in table 1 tells us that the five states that introduced MCTs during the 1990s had significantly larger improvements on NAEP tests than states that made no change in their student accountability regime. The gains, however, are smaller than for the states introducing Universal CBEEES. New York and North Carolina. The most positive finding about MCTs is that students in MCT states earn significantly more during the first eight years after graduation than comparable students in other states suggesting that MCTs improve employer perceptions of the quality of the recent graduates of local high schools
Well-Posed Initial-Boundary Evolution in General Relativity
Maximally dissipative boundary conditions are applied to the initial-boundary
value problem for Einstein's equations in harmonic coordinates to show that it
is well-posed for homogeneous boundary data and for boundary data that is small
in a linearized sense. The method is implemented as a nonlinear evolution code
which satisfies convergence tests in the nonlinear regime and is robustly
stable in the weak field regime. A linearized version has been stably matched
to a characteristic code to compute the gravitational waveform radiated to
infinity.Comment: 5 pages, 6 figures; added another convergence plot to Fig. 2 + minor
change
Instability of generalised AdS black holes and thermal field theory
We study black holes in AdS-like spacetimes, with the horizon given by an
arbitrary positive curvature Einstein metric. A criterion for classical
instability of such black holes is found in the large and small black hole
limits. Examples of large unstable black holes have a B\"ohm metric as the
horizon. These, classically unstable, large black holes are locally
thermodynamically stable. The gravitational instability has a dual description,
for example by using the version of the AdS/CFT
correspondence. The instability corresponds to a critical temperature of the
dual thermal field theory defined on a curved background.Comment: 1+16 pages. 1 figure. LaTeX. Minor clarification
Infinitesimal and local convexity of a hypersurface in a semi-Riemannian manifold
Given a Riemannian manifold M and a hypersurface H in M, it is well known
that infinitesimal convexity on a neighborhood of a point in H implies local
convexity. We show in this note that the same result holds in a semi-Riemannian
manifold. We make some remarks for the case when only timelike, null or
spacelike geodesics are involved. The notion of geometric convexity is also
reviewed and some applications to geodesic connectedness of an open subset of a
Lorentzian manifold are given.Comment: 14 pages, AMSLaTex, 2 figures. v2: typos fixed, added one reference
and several comments, statement of last proposition correcte
New Einstein-Sasaki and Einstein Spaces from Kerr-de Sitter
In this paper, which is an elaboration of our results in hep-th/0504225, we
construct new Einstein-Sasaki spaces L^{p,q,r_1,...,r_{n-1}} in all odd
dimensions D=2n+1\ge 5. They arise by taking certain BPS limits of the
Euclideanised Kerr-de Sitter metrics. This yields local Einstein-Sasaki metrics
of cohomogeneity n, with toric U(1)^{n+1} principal orbits, and n real
non-trivial parameters. By studying the structure of the degenerate orbits we
show that for appropriate choices of the parameters, characterised by the (n+1)
coprime integers (p,q,r_1,...,r_{n-1}), the local metrics extend smoothly onto
complete and non-singular compact Einstein-Sasaki manifolds
L^{p,q,r_1,...,r_{n-1}}. We also construct new complete and non-singular
compact Einstein spaces \Lambda^{p,q,r_1,...,r_n} in D=2n+1 that are not
Sasakian, by choosing parameters appropriately in the Euclideanised Kerr-de
Sitter metrics when no BPS limit is taken.Comment: latex, 26 page
Convex domains of Finsler and Riemannian manifolds
A detailed study of the notions of convexity for a hypersurface in a Finsler
manifold is carried out. In particular, the infinitesimal and local notions of
convexity are shown to be equivalent. Our approach differs from Bishop's one in
his classical result (Bishop, Indiana Univ Math J 24:169-172, 1974) for the
Riemannian case. Ours not only can be extended to the Finsler setting but it
also reduces the typical requirements of differentiability for the metric and
it yields consequences on the multiplicity of connecting geodesics in the
convex domain defined by the hypersurface.Comment: 22 pages, AMSLaTex. Typos corrected, references update
Thermal diffusion of supersonic solitons in an anharmonic chain of atoms
We study the non-equilibrium diffusion dynamics of supersonic lattice
solitons in a classical chain of atoms with nearest-neighbor interactions
coupled to a heat bath. As a specific example we choose an interaction with
cubic anharmonicity. The coupling between the system and a thermal bath with a
given temperature is made by adding noise, delta-correlated in time and space,
and damping to the set of discrete equations of motion. Working in the
continuum limit and changing to the sound velocity frame we derive a
Korteweg-de Vries equation with noise and damping. We apply a collective
coordinate approach which yields two stochastic ODEs which are solved
approximately by a perturbation analysis. This finally yields analytical
expressions for the variances of the soliton position and velocity. We perform
Langevin dynamics simulations for the original discrete system which fully
confirm the predictions of our analytical calculations, namely noise-induced
superdiffusive behavior which scales with the temperature and depends strongly
on the initial soliton velocity. A normal diffusion behavior is observed for
very low-energy solitons where the noise-induced phonons also make a
significant contribution to the soliton diffusion.Comment: Submitted to PRE. Changes made: New simulations with a different
method of soliton detection. The results and conclusions are not different
from previous version. New appendixes containing information about the system
energy and soliton profile
New Results in Sasaki-Einstein Geometry
This article is a summary of some of the author's work on Sasaki-Einstein
geometry. A rather general conjecture in string theory known as the AdS/CFT
correspondence relates Sasaki-Einstein geometry, in low dimensions, to
superconformal field theory; properties of the latter are therefore reflected
in the former, and vice versa. Despite this physical motivation, many recent
results are of independent geometrical interest, and are described here in
purely mathematical terms: explicit constructions of infinite families of both
quasi-regular and irregular Sasaki-Einstein metrics; toric Sasakian geometry;
an extremal problem that determines the Reeb vector field for, and hence also
the volume of, a Sasaki-Einstein manifold; and finally, obstructions to the
existence of Sasaki-Einstein metrics. Some of these results also provide new
insights into Kahler geometry, and in particular new obstructions to the
existence of Kahler-Einstein metrics on Fano orbifolds.Comment: 31 pages, no figures. Invited contribution to the proceedings of the
conference "Riemannian Topology: Geometric Structures on Manifolds"; minor
typos corrected, reference added; published version; Riemannian Topology and
Geometric Structures on Manifolds (Progress in Mathematics), Birkhauser (Nov
2008
- …