Simulation of multivariate diffusion bridge

We propose simple methods for multivariate diffusion bridge simulation, which plays a fundamental role in simulation-based likelihood and Bayesian inference for stochastic differential equations. By a novel application of classical coupling methods, the new approach generalizes a previously proposed simulation method for one-dimensional bridges to the multi-variate setting. First a method of simulating approximate, but often very accurate, diffusion bridges is proposed. These approximate bridges are used as proposal for easily implementable MCMC algorithms that produce exact diffusion bridges. The new method is much more generally applicable than previous methods. Another advantage is that the new method works well for diffusion bridges in long intervals because the computational complexity of the method is linear in the length of the interval. In a simulation study the new method performs well, and its usefulness is illustrated by an application to Bayesian estimation for the multivariate hyperbolic diffusion model.Comment: arXiv admin note: text overlap with arXiv:1403.176

Integrable anyon chains: from fusion rules to face models to effective field theories

Starting from the fusion rules for the algebra $SO(5)_2$ we construct one-dimensional lattice models of interacting anyons with commuting transfer matrices of `interactions round the face' (IRF) type. The conserved topological charges of the anyon chain are recovered from the transfer matrices in the limit of large spectral parameter. The properties of the models in the thermodynamic limit and the low energy excitations are studied using Bethe ansatz methods. Two of the anyon models are critical at zero temperature. From the analysis of the finite size spectrum we find that they are effectively described by rational conformal field theories invariant under extensions of the Virasoro algebra, namely $\mathcal{W}B_2$ and $\mathcal{W}D_5$, respectively. The latter contains primaries with half and quarter spin. The modular partition function and fusion rules are derived and found to be consistent with the results for the lattice model.Comment: 43 pages, published versio

Governmental Conspiracies to Violate Civil Rights: A Theory Reconsidered

Governmental Conspiracies to Violate Civil Rights: A Theory Reconsidere

A Theoretical Study of Quantum Ballistic Transport in Semiconductor Ring Structures

Recent developments in microfabrication technology have enabled the manufacture of semiconductor devices in which the carriers scatter very infrequently over typical device lengths. Transport of this kind is termed ballistic, and under such conditions, coherent quantum interference phenomena become an increasingly important part of the conduction process. In particular, the conductors of such devices now assume the role of electron waveguides. Most previous attempts at modelling quantum ballistic transport have been based on one-dimensional models. However, relatively little was known about the true nature of wavepacket propagation in real structures where diffraction from apertures or around obstacles could occur. This thesis presents the first theoretical study of quantum ballistic transport in a two-dimensional quantum waveguide network. The study specifically concentrates on modelling the Aharonov-Bohm effect in ring structures, which is an exclusively quantum-mechanical effect. The method of investigation was to numerically solve the two-dimensional time-dependent Schrodinger equation for an idealised ring structure using a computer algorithm which incorporated several novel techniques. One-dimensional calculations show that one can expect a modulation depth of 100% in the oscillations in the magneto-resistance characteristic of such rings. Present oscillation amplitudes measured experimentally however fall far short of this figure, typically being about 0.1% of the background resistance in metal rings and about 10% in rings formed in the two-dimensional electron gas at a heterojunction interface. Computer simulation of wavepacket propagation in these latter structures clearly show a multi-mode structure in the wavefunction across the conductors of realistically-sized rings. It is shown that it is the transmission of more than one mode at the exit of the ring which is a major factor in reducing the amplitude of the magneto-resistance oscillations. Good agreement between the average magneto-resistance oscillation amplitude in the simulated and experimental characteristics for a ring formed at a heterojunction was obtained. The two-dimensional model can therefore be regarded as a major improvement on earlier one-dimensional models. Evidence suggesting a damping of the magneto-resistance oscillations as a result of the direct action of the magnetic field acting on the conductors is also found. It is estimated that the approximate cut-off field would be about 0.5 Tesla for the particular device modelled, which is consistent with experimental observations of a decline in the oscillation amplitude in the range 0.5-1.0 Tesla. A modification of the basic ring structure to achieve larger magneto-resistance oscillations by constricting the exit of the ring is proposed and computer simulation of wavepacket propagation through this structure shows that a substantial increase in modulation depth can be expected. The techniques developed in this thesis have therefore been able to successfully model existing quantum interference devices and also assess the likely improvement in performance of a hypothetical device. These techniques could a be applied to the modelling of wavepacket propagation in other types of sub-micron quantum-interference devices where transport can be considered to be ballistic

New digital realities in a fragmented, 'brave new world'

This paper proposes a scheme to categorize diverse embodied experiences of digital nomadism. Digitization has drastically altered how people engage in time and space. While there are many potential ways to classify the digital nomad, this approach looks at how individuals might experience embodimen

Limited Space: Allocating the Geostationary Orbit

In many ways, the space shuttle inaugurated a new phase in the development of space as an international resource. The shuttle may be used to launch satellites into orbit and has the additional capability of retrieving and repairing satellites. As the number of satellites in orbit increases, the problem of interference among satellites escalates. The issue centers around the geostationary orbit and the electromagnetic spectrum as well as direct satellite broadcasting from orbiting transmission stations to individual receivers. This Comment will examine the current legal and probable future state of the international zone known as the geostationary orbit and the corresponding issue of direct satellite broadcasting. Additionally, this Comment will analyze the impact of the varying positions of states regarding the geostationary orbit, direct satellite broadcasting, and the likelihood of international agreement on issues regarding these concerns. Finally, this Comment will propose possible solutions consistent with current international law

The Empirical Challenge to Death-Qualified Juries: On Further Examination

I. Introduction II. Community Representation on the Death-Qualfied Jury … A. Establishing a Fair-Cross-Section Violation ... B. The Representation of Community Attitudes on Death-Qualified Juries ... C. The Representation of Minorities and Women on Death-Qualified Juries ... D. The Cumulative Effects of Death Qualification on the Representativeness of Juries III. The Conviction Proneness of Death-Qualfied Juries ... A. The Evidence on Conviction Proneness IV. Some Concluding Thoughts on the Challenge of Death Qualification ... A. Defining the Category of Excludable Jurors ... B. The Normative Issues Posed by Death Qualification V. Conclusion Appendi