45,802 research outputs found
Noose or Lifeline? The Role of Transport in Independent Namibia
INTRODUCTION
As the struggle to end apartheid in South Africa intensifies, attention has increasingly been distracted fran the vexed issue of Namibian independence. All parties to the dispute have agreed for at least eight years on the desirability of independence for Africa's last colony, but attainment of that goal has been continually frustrated by South Africa; through the introduction of new obstacles. The current deadlock is over Pretoria's insistence that independence be linked to the withdrawal of Cuban troops from Angola. Meanwhile, yet another interim government has been appointed in Windhoek, onto which South Africa is making a sustained attempt to confer legitimacy as oppsition to SWAPO.
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Transport Priority Assessment Techniques Developed by British Local Authorities: A Synopsis and Review
INTRODUCTION
This Working Paper is the first in a series reporting progress on a 2-year ESRC-funded research project entitled "Priority Assessment Techniques for Local Transport Improvement Projects" ; and directed by Prof. A.D. May; Dr. A. D. Pearlman and Mr P.J. Mackie. The project's objectives - to be pursued in successive phases - are threefold: to undertake a critical review of the various techniques adopted by different local authorities: to obtain fmn the review a representative sample of methods for more detailed comprison and testing on a set of schemes for which data are available: and to combine the exprience thus gained with wider pactical and theoretical knowledge of multiple criteria assessment issues, in order to develop a model technique that overcomes existing problems and thereby contributes to better decision making
Quantum Sensors: Improved Optical Measurement via Specialized Quantum States
Classical measurement strategies in many areas are approaching their maximum
resolution and sensitivity levels, but these levels often still fall far short
of the ultimate limits allowed by the laws of physics. To go further,
strategies must be adopted that take into account the quantum nature of the
probe particles and that optimize their quantum states for the desired
application. Here, we review some of these approaches, in which quantum
entanglement, the orbital angular momentum of single photons, and quantum
interferometry are used to produce optical measurements beyond the classical
limit
Pulsar Braking Indices Revisited
Using the standard equation for the slowdown of a neutron star, we derive a
formula for the braking index via integration rather than the conventional
differentiation. The new formula negates the need to measure the second time
derivative of the rotation frequency. We show that the method gives similar
braking indices for PSR B1509-58 and the Crab pulsar to those already in the
literature. We point out that our method is useful for obtaining the braking
indices of moderate aged pulsars without the need for long, phase-connected
timing solutions. We applied the method to 20 pulsars and discuss the
implications of the results. We find that virtually all the derived braking
indices are dominated by the effects of (unseen) glitches, the recovery from
which corrupts the value of the frequency first derivative. However, any real,
large, positive braking index has implications for magnetic field decay and
offers support to recent models of pulsar evolution.Comment: 5 pages, 2 figures, 1 table, accepted by MNRA
Jost Functions and Jost Solutions for Jacobi Matrices, II. Decay and Analyticity
We present necessary and sufficient conditions on the Jost function for the
corresponding Jacobi parameters and to have a given degree of
exponential decay.Comment: 28 page
From Jack polynomials to minimal model spectra
In this note, a deep connection between free field realisations of conformal
field theories and symmetric polynomials is presented. We give a brief
introduction into the necessary prerequisites of both free field realisations
and symmetric polynomials, in particular Jack symmetric polynomials. Then we
combine these two fields to classify the irreducible representations of the
minimal model vertex operator algebras as an illuminating example of the power
of these methods. While these results on the representation theory of the
minimal models are all known, this note exploits the full power of Jack
polynomials to present significant simplifications of the original proofs in
the literature.Comment: 14 pages, corrected typos and added comment on connections to the AGT
conjecture in introduction, version to appear in J. Phys.
Switch access to technology - A comprehensive Guide.
When most of us use a computer we use the standard interface of a keyboard and mouse. However, what do you do if you cannot use a keyboard or mouse? A number of alternative access systems exist, for example: alternative keyboards, tracker balls, touchscreens, head pointers etc. But for some people these devices are also an impossibility, and this is where switches 'kick in'. The main subject of this document is the switch user. For completeness we have include a brief mention of other input devices, which may be grouped together as 'alternative access systems'.We aim to: - Encourage developers to include switch access into their products - Standardise practice and terminology. This document explains some of the issues involved for people with severe physical difficulties who access computers and other electronic devices with switches. It details the ways in which switch users interact with computer programs and other technology designed to be directly accessible to them. The document includes some precise definitions of terms. It also attempts to survey the whole range of issues associated with switch use. As such it should be useful to professionals working or entering the field, those software developers considering switch users for the first time and also for those already developing in this area
Lifting flat directions in lattice supersymmetry
We present a procedure to improve the lattice definition of
supersymmetric Yang--Mills theory. The lattice construction necessarily
involves U(1) flat directions, and we show how these can be lifted without
violating the exact lattice supersymmetry. The basic idea is to modify the
equations of motion of an auxiliary field, which determine the moduli space of
the system. Applied to numerical calculations, the resulting improved lattice
action leads to dramatically reduced violations of supersymmetric Ward
identities and much more rapid approach to the continuum limit
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