55,464 research outputs found
Time dependent fluctuations and particle production in cosmological de Sitter and anti-de Sitter spaces
We study the evolution of time-dependent fluctuations and particle production
in an expanding dS and contracting AdS universe. Using the functional
Schrodinger formalism we are able to probe the time dependent regime which is
out of the reach of the standard approximations like the Bogolyubov method. In
both cases, the evolution of fluctuations is governed by the harmonic
oscillator equation with time dependent frequency. In the case of an expanding
dS universe we explicitly show that the frequency of fluctuations produced at a
certain moment diminish in time, while the distribution of the created
particles quickly approaches the thermal radiation of the dS space. In the case
of a contracting AdS universe we show that the frequency of fluctuations
produced at a certain moment grow in time. Nominally, the temperature of
radiation diverges as the Big Crunch is approaching, however, increasing
oscillations of the spectrum make the temperature poorly defined, which is in
agreement with the fact that AdS space does not have an event horizon which
would cause thermal radiation. Unlimited growth of fluctuations indicates that
an eventual tunneling into AdS vacuum would have catastrophic consequences for
our universe.Comment: 8 pages, 6 figure
Time Evolution of Temperature and Entropy of Various Collapsing Domain Walls
We investigate the time evolution of the temperature and entropy of
gravitationally collapsing domain walls as seen by an asymptotic observer. In
particular, we seek to understand how topology and the addition of a
cosmological constant affect the gravitational collapse. Previous work has
shown that the entropy of a spherically symmetric collapsing domain approaches
a constant. In this paper, we reproduce these results, using both a fully
quantum and a semi-classical approach, then we repeat the process for a de
Sitter Schwarzschild domain wall (spherical with cosmological constant) and a
(3+1) BTZ domain wall (cylindrical). We do this by coupling a scalar field to
the background of the domain wall and analyzing the spectrum of radiation as a
function of time. We find that the spectrum is quasi-thermal, with the degree
of thermality increasing as the domain wall approaches the horizon. The thermal
distribution allows for the determination of the temperature as a function of
time, and we find that the late time temperature is very close to the Hawking
temperature and that it also exhibits the proper scaling with the mass. From
the temperature we find the entropy. Since the collapsing domain wall is what
forms a black hole, we can compare the results to those of the standard
entropy-area relation. We find that the entropy does in fact approach a
constant that is close to the Hawking entropy. However, both the de Sitter
Schwarzschild domain wall and the (3+1) BTZ domain wall show periods of
decreasing entropy, which suggests that spontaneous collapse may be prevented.Comment: This paper is a merging of two previously submitted papers: Time
Evolution of Temperature and Entropy of a Gravitationally Collapsing Cylinder
[arXiv:1106.2278]; Time Evolution of Temperature and Entropy of a
Gravitationally Collapsing de Sitter Schwarzschild Domain Wal
Information systems planning and management in New Zealand tertiary education institutions : a thesis presented in partial fulfilment of the requirements for the degree of Master of Philosophy in Computer Science at Massey University
The strategic use of information systems for competitive advantage is a subject of current information systems research. This thesis examines the application of this view of the organisation on tertiary education institutions in New Zealand, and its impact on their information systems planning process. Recent changes in the legislation governing the tertiary education sector are reviewed, and their effects on New Zealand tertiary institutions are examined. A number of models of information systems development are summarised and used as a framework to position the current state of information systems in tertiary institutions. The results of a survey, which gathered information about the information systems planning in New Zealand's tertiary education institutions, are presented. Several models of information systems planning are examined and their applicability to the organisations involved in tertiary education is determined. A suggested development of information systems planning within tertiary institutions is presented
SLIP4EX- a program for routine slope stability analysis to include the effects of vegetation, reinforcement and hydrological changes
SLIP4EX is a straightforward computer program developed in connection with the EU funded ECOSLOPES project for routine stability analysis and the assessment of the contribution of vegetation to slope stability. The slope section is drawn up and dimensions and parameters are fed in to the Microsoft Excel based program for stability calculations and comparisons of Factors of Safety using different methods of analysis (Bishop, Janbu, Fellenius, Simple, Greenwood). The background and assumptions involved in the derivation of each of the methods is briefly described. The simplicity of the program enables the user to understand the nature of the analysis, explore the parameter assumptions made and compare the different methods of analysis. Soil reinforcement by geosynthetic layers or anchors, and vegetation effects of enhanced cohesion, changed water pressures, mass of vegetation, wind forces and root reinforcement forces are readily included in the analysis. The program is freely available on request from the author
Educational Adequacy in Arkansas: Facilities
Public school facilities funding was approached somewhat differently from the remainder of the work on public schools resulting from Lake View. A primary concern regarding school facilities was the lack of a comprehensive assessment of some 1200 schools in the state in over 250 independent public school districts. Early in the process, the General Assembly created the Joint Committee on Education Facilities in April 2003. This report covers the work of this Committee from the process of assessment through the reports of the Arkansas Division of Public School Academic Facilities & Transportation, a unit of the Arkansas Department of Education, charged with annual assessments of the progress being made in the improvement of school facilities
Higher Education Marketing to the Hispanic Student Population
The Hispanic population in the United States is growing at an unprecedented rate. The U.S. Census Bureau projects the Hispanic population to make up nearly 25% of the entire United States population by the year 2050. This population growth points at a large market for products and services in the U.S., including higher education. This thesis discussion will address characteristics of the Hispanic population in the United States of America, explore the importance of a diverse student population including Hispanic students on a college or university campus, evaluate the competitiveness University of New Hampshire’s current situation with regard to Hispanic students, and recommend methods through which the University of New Hampshire can improve its approach in marketing its services to Hispanic students
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