3,008 research outputs found
Wetland mapping from digitized aerial photography
Computer assisted interpretation of small scale aerial imagery was found to be a cost effective and accurate method of mapping complex vegetation patterns if high resolution information is desired. This type of technique is suited for problems such as monitoring changes in species composition due to environmental factors and is a feasible method of monitoring and mapping large areas of wetlands. The technique has the added advantage of being in a computer compatible form which can be transformed into any georeference system of interest
The Coherence of Primordial Fluctuations Produced During Inflation
The behaviour of quantum metric perturbations produced during inflation is
considered at the stage after the second Hubble radius crossing. It is shown
that the classical correlation between amplitude and momentum of a perturbation
mode, previously shown to emerge in the course of an effective
quantum-to-classical transition, is maintained for a sufficiently long time,
and we present the explicit form in which it takes place using the Wigner
function. We further show with a simple diffraction experiment that quantum
interference, non-expressible in terms of a classical stochastic description of
the perturbations, is essentially suppressed. Rescattering of the perturbations
leads to a comparatively slow decay of this correlation and to a complete
stochastization of the system.Comment: LaTeX (7 pages
Interdisciplinary research on the application of ERTS-1 data to the regional land use planning process
The author has identified the following significant results. Although the degree to which ERTS-1 imagery can satisfy regional land use planning data needs is not yet known, it appears to offer means by which the data acquisition process can be immeasurably improved. The initial experiences of an interdisciplinary group attempting to formulate ways of analyzing the effectiveness of ERTS-1 imagery as a base for environmental monitoring and the resolution of regional land allocation problems are documented. Application of imagery to the regional planning process consists of utilizing representative geographical regions within the state of Wisconsin. Because of the need to describe and depict regional resource complexity in an interrelatable state, certain resources within the geographical regions have been inventoried and stored in a two-dimensional computer-based map form. Computer oriented processes were developed to provide for the economical storage, analysis, and spatial display of natural and cultural data for regional land use planning purposes. The authors are optimistic that the imagery will provide revelant data for land use decision making at regional levels
The use of ERTS-1 data for the inventory of critical land resources for regional land use planning
Computer-generated spatial and statistical comparisons of critical land resource data derived from conventional sources, RB-57 photographs, and ERTS images, for an eastern Wisconsin test site, suggest that certain critical land resource data can be mapped from ERTS images on a statewide basis. This paper presents one of the biotic resources, wetlands, as an example of the use of ERTS imagery to inventory land resources
Estimation and optimal designing under latent variable models for paired comparisons studies via a multiplicative algorithm
We consider:<BR/>
1. The problem of estimating the parameters of latent variable models such as the Bradley Terry or Thurstone Model by the method of maximum likelihood, given data from a paired comparisons experiment. The parameters of these models can be taken to be weights which are positive and sum to one;<BR/>
2. The problem of determining approximate locally optimal designs for good estimation of these parameters; i.e of determining optimal design weights which are also positive and sum to one
Mass Spectrum and Statistical Entropy of the BTZ black hole from Canonical Quantum Gravity
In a recent publication we developed a canonical quantization program
describing the gravitational collapse of a spherical dust cloud in 2+1
dimensions with a negative cosmological constant . In
this paper we address the quantization of the Banados--Teitelboim--Zanelli
(BTZ) black hole. We show that the mass function describing the black hole is
made of two pieces, a constant non-vanishing boundary contribution and a
discrete spectrum of the form . The
discrete spectrum is obtained by applying the Wheeler--DeWitt equation with a
particular choice of factor ordering and interpreted as giving the energy
levels of the collapsed matter shells that form the black hole. Treating a
black hole microstate as a particular distribution of shells among the levels,
we determine the canonical entropy of the BTZ black hole. Comparison with the
Bekenstein--Hawking entropy shows that the boundary energy is related to the
central charge of the Virasoro algebra that generates the asymptotic symmetry
group of the three-dimensional anti-de Sitter space AdS. This gives a
connection between the Wheeler--DeWitt approach and the conformal field theory
approach.Comment: 15 pages, no figures. Two explanatory paragraphs have been added.
This version will appear in Physical Review
Semiclassical approximation to supersymmetric quantum gravity
We develop a semiclassical approximation scheme for the constraint equations
of supersymmetric canonical quantum gravity. This is achieved by a
Born-Oppenheimer type of expansion, in analogy to the case of the usual
Wheeler-DeWitt equation. The formalism is only consistent if the states at each
order depend on the gravitino field. We recover at consecutive orders the
Hamilton-Jacobi equation, the functional Schrodinger equation, and quantum
gravitational correction terms to this Schrodinger equation. In particular, the
following consequences are found:
(i) the Hamilton-Jacobi equation and therefore the background spacetime must
involve the gravitino, (ii) a (many fingered) local time parameter has to be
present on (the space of all possible tetrad and gravitino
fields), (iii) quantum supersymmetric gravitational corrections affect the
evolution of the very early universe. The physical meaning of these equations
and results, in particular the similarities to and differences from the pure
bosonic case, are discussed.Comment: 34 pages, clarifications added, typos correcte
Evaluation of the application of ERTS-1 data to the regional land use planning process
The author has identified the following significant results. Employing simple and economical extraction methods, ERTS can provide valuable data to the planners at the state or regional level with a frequency never before possible. Interactive computer methods of working directly with ERTS digital information show much promise for providing land use information at a more specific level, since the data format production rate of ERTS justifies improved methods of analysis
Evolutionary quantum cosmology in a gauge-fixed picture
We study the classical and quantum models of a flat
Friedmann-Robertson-Walker (FRW) space-time, coupled to a perfect fluid, in the
context of the consensus and a gauge-fixed Lagrangian frameworks. It is shown
that, either in the usual or in the gauge-fixed actions, the evolution of the
universe based on the classical cosmology represents a late time power law
expansion, coming from a big-bang singularity in which the scale factor goes to
zero for the standard matter, and tending towards a big-rip singularity in
which the scale factor diverges for the phantom fluid. We then employ the
familiar canonical quantization procedure in the given cosmological setting to
find the cosmological wave functions in the corresponding minisuperspace. Using
a gauge-fixed (reduced) Lagrangian, we show that, it may lead to a
Schr\"{o}dinger equation for the quantum-mechanical description of the model
under consideration, the eigenfunctions of which can be used to construct the
time dependent wave function of the universe. We use the resulting wave
function in order to investigate the possibility of the avoidance of classical
singularities due to quantum effects by means of the many-worlds and
ontological interpretation of quantum cosmology.Comment: 15 pages, 10 figures, typos corrected, Refs. adde
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