Quantum Logic and the Histories Approach to Quantum Theory

An extended analysis is made of the Gell-Mann and Hartle axioms for a generalised `histories' approach to quantum theory. Emphasis is placed on finding equivalents of the lattice structure that is employed in standard quantum logic. Particular attention is given to `quasi-temporal' theories in which the notion of time-evolution is less rigid than in conventional Hamiltonian physics; theories of this type are expected to arise naturally in the context of quantum gravity and quantum field theory in a curved space-time. The quasi-temporal structure is coded in a partial semi-group of `temporal supports' that underpins the lattice of history propositions. Non-trivial examples include quantum field theory on a non globally-hyperbolic spacetime, and a simple cobordism approach to a theory of quantum topology. It is shown how the set of history propositions in standard quantum theory can be realised in such a way that each history proposition is represented by a genuine projection operator. This provides valuable insight into the possible lattice structure in general history theories, and also provides a number of potential models for theories of this type.Comment: TP/92-93/39 36 pages + one page of diagrams (I could email Apple laser printer postscript file for anyone who is especially keen

Simulating Quantum Mechanics by Non-Contextual Hidden Variables

No physical measurement can be performed with infinite precision. This leaves a loophole in the standard no-go arguments against non-contextual hidden variables. All such arguments rely on choosing special sets of quantum-mechanical observables with measurement outcomes that cannot be simulated non-contextually. As a consequence, these arguments do not exclude the hypothesis that the class of physical measurements in fact corresponds to a dense subset of all theoretically possible measurements with outcomes and quantum probabilities that \emph{can} be recovered from a non-contextual hidden variable model. We show here by explicit construction that there are indeed such non-contextual hidden variable models, both for projection valued and positive operator valued measurements.Comment: 15 pages. Journal version. Only minor typo corrections from last versio

Covariant quantum measurements may not be optimal

Quantum particles, such as spins, can be used for communicating spatial directions to observers who share no common coordinate frame. We show that if the emitter's signals are the orbit of a group, then the optimal detection method may not be a covariant measurement (contrary to widespread belief). It may be advantageous for the receiver to use a different group and an indirect estimation method: first, an ordinary measurement supplies redundant numerical parameters; the latter are then used for a nonlinear optimal identification of the signal.Comment: minor corrections, to appear in J. Mod. Opt. (proc. of Gdansk conf.

Panel: Perspectives on External Threats to the National Parks [Report of the Subgroup of the Park Protection Working Group]

11 pages. Contains 1 attachment

Prairie Pothole Regional Studies

The U.S. Geological Survey (USGS) conducted a comprehensive, stratified survey of 204 wetland catchments in 1997 and 270 catchments in 2004, a subset of more than 2 million hectares of wetland and grassland systems established on Conservation Reserve Program (CRP) and Wetlands Reserve Program (WRP) lands. The purpose of the survey was to gather data for estimating a variety of ecosystem services provided by prairie pothole wetland catchments. In early 2008, USGS published a preliminary findings report as a result of these studies

State judicial selection methods as public policy: The Missouri plan

State judiciaries are foundational institutions of governance in the United States. They are coequal, policy-making branches of government whose members, along with the legislative and executive branches, are constitutionally authorized and empowered in all fifty American states. Extant research on judicial selection in the American states provides neither a comprehensive theory of why states choose their particular judicial selection method nor a comprehensive empirical assessment of this important question. This research seeks to fill this lacuna by increasing understanding of American state courts through the formulation of a theory of state judicial selection, a short but comprehensive history of state judicial selection reform, and an event history analysis of the adoption of merit selection by states for choosing judges to their courts of last. The major finding is that, similar to other institutional arrangements, state judicial selection methods are highly path dependent. Once established, they are on a trajectory which is difficult to alter. An important secondary finding is that lawyers play a significant role in bringing about judicial selection reform when and where the possibility of change arises. They are incentivized actors who historically have taken the lead in judicial selection reform efforts. Geography also seems to be an influential factor in judicial selection reform, suggesting that reform-minded states take cues and learn and from their neighbors

Prairie Pothole Regional Studies

The U.S. Geological Survey (USGS) conducted a comprehensive, stratified survey of 204 wetland catchments in 1997 and 270 catchments in 2004, a subset of more than 2 million hectares of wetland and grassland systems established on Conservation Reserve Program (CRP) and Wetlands Reserve Program (WRP) lands. The purpose of the survey was to gather data for estimating a variety of ecosystem services provided by prairie pothole wetland catchments. In early 2008, USGS published a preliminary findings report as a result of these studies

Negativity and contextuality are equivalent notions of nonclassicality

Two notions of nonclassicality that have been investigated intensively are: (i) negativity, that is, the need to posit negative values when representing quantum states by quasiprobability distributions such as the Wigner representation, and (ii) contextuality, that is, the impossibility of a noncontextual hidden variable model of quantum theory (also known as the Bell-Kochen-Specker theorem). Although both of these notions were meant to characterize the conditions under which a classical explanation cannot be provided, we demonstrate that they prove inadequate to the task and we argue for a particular way of generalizing and revising them. With the refined version of each in hand, it becomes apparent that they are in fact one and the same. We also demonstrate the impossibility of noncontextuality or nonnegativity in quantum theory with a novel proof that is symmetric in its treatment of measurements and preparations.Comment: 5 pages, published version (modulo some supplementary material

Multispectral system analysis through modeling and simulation

The design and development of multispectral remote sensor systems and associated information extraction techniques should be optimized under the physical and economic constraints encountered and yet be effective over a wide range of scene and environmental conditions. Direct measurement of the full range of conditions to be encountered can be difficult, time consuming, and costly. Simulation of multispectral data by modeling scene, atmosphere, sensor, and data classifier characteristics is set forth as a viable alternative, particularly when coupled with limited sets of empirical measurements. A multispectral system modeling capability is described. Use of the model is illustrated for several applications - interpretation of remotely sensed data from agricultural and forest scenes, evaluating atmospheric effects in LANDSAT data, examining system design and operational configuration, and development of information extraction techniques

Wheat signature modeling and analysis for improved training statistics: Supplement. Simulated LANDSAT wheat radiances and radiance components

Simulated scanner system data values generated in support of LACIE (Large Area Crop Inventory Experiment) research and development efforts are presented. Synthetic inband (LANDSAT) wheat radiances and radiance components were computed and are presented for various wheat canopy and atmospheric conditions and scanner view geometries. Values include: (1) inband bidirectional reflectances for seven stages of wheat crop growth; (2) inband atmospheric features; and (3) inband radiances corresponding to the various combinations of wheat canopy and atmospheric conditions. Analyses of these data values are presented in the main report