Wireless Network Stability in the SINR Model

We study the stability of wireless networks under stochastic arrival processes of packets, and design efficient, distributed algorithms that achieve stability in the SINR (Signal to Interference and Noise Ratio) interference model. Specifically, we make the following contributions. We give a distributed algorithm that achieves $\Omega(\frac{1}{\log^2 n})$-efficiency on all networks (where $n$ is the number of links in the network), for all length monotone, sub-linear power assignments. For the power control version of the problem, we give a distributed algorithm with $\Omega(\frac{1}{\log n(\log n + \log \log \Delta)})$-efficiency (where $\Delta$ is the length diversity of the link set).Comment: 10 pages, appeared in SIROCCO'1

Supporting level 1 physics & astronomy undergraduates at the University of Glasgow

It is generally accepted that the retention and associated completion rates for first year classes are an area of concern for UK universities, and physics and astronomy classes at the University of Glasgow are exception. Classes are often large and, as result, student integration on academic and social levels can be difficult to achieve; some students perceive a lack of personal interest and support in what can be a stressful transition from secondary to tertiary education. In order to address these issues, the author has been employed in a new departmental post, Director of Learning Support for First Year. The remit of this post is primarily the implementation of an improved personal contact and academic monitoring and support strategy for first year undergraduates. The purpose of this paper is to present the ways in which it is hoped that the role of Director of Learning Support will positively impact on aspects of the forthcoming academic year

Water quality and nutrient dynamics - Lake Victoria, Kenya

Limnological studies in Lake Victoria (Kenyan portion) have been sporadic. Water quality and nutrient dynamics studies are being undertaken in fifteen sampling sites that have been divided into four ecological zones namely: Nyanza Gulf, Rusinga Channel, open waters inshore and open waters. The ongoing study will show how the physical and chemical paramenters affect fish distribution and abundance

Tribology matters

Tribology touches every aspect of our day to day existence and the wonder of this is that we are completely unaware how central it is to how we function. Take a snapshot of thebeginning of a normal working day for example. A typical morning start will involve brushing one's teeth with toothpaste containing mild abrasive (with a toothbrush with an optimized design for brushing efficiency), using a shampoo and conditioner which have been tested for frictional properties on a wide range of hair types, and for those who have the traditional morning fry up - lubricating the pan in advance with cooking oil to provide a boundary layer between the food and the pan and to reduce adhesion and heat transfer. It is clear that tribology plays a major role in our everyday lives. Whether starting out for work by foot, bicycle or car, friction will define whether our shoes or tyres can grip the road surface and whether the brake or clutch will do their job. If it is raining, the speed limit is modified in some countries, testifying to the influence of tribologists in decision making in the transport industries

"The honor of firing before His Majesty": Patrick Ferguson's will and the Royal Armouries’ Ferguson rifle

Patrick Ferguson (1744-80) designed the first breech-loading rifle to be used by the British Army. In November 2000, the Royal Armouries purchased an early example, formerly in the possession of the Fergusons of Pitfour, descendants of Patrick's younger brother, George. Patrick Ferguson's will has helped the author identify the Royal Armouries' Ferguson Rifle as the one which Patrick Ferguson used when he demonstrated it before George III and Queen Charlotte at Windsor in 1776

On Wireless Scheduling Using the Mean Power Assignment

In this paper the problem of scheduling with power control in wireless networks is studied: given a set of communication requests, one needs to assign the powers of the network nodes, and schedule the transmissions so that they can be done in a minimum time, taking into account the signal interference of concurrently transmitting nodes. The signal interference is modeled by SINR constraints. Approximation algorithms are given for this problem, which use the mean power assignment. The problem of schduling with fixed mean power assignment is also considered, and approximation guarantees are proven

Tribo-corrosion maps for application in bio-tribology : some new approaches

Advances in the study of tribo-corrosion of materials in recent years have included the development of mechanistic maps, showing the transitions between the regimes as a function of the main process parameters. In such cases, maps have been constructed in both two and three dimensions. There are now a variety of modelling algorithms which may be used to map a range of performance indicators over a multi-parameter space. The interactions of tribo-corrosion in biological environments are becoming of increasing importance

An exercise in transformational programming: Backtracking and Branch-and-Bound

We present a formal derivation of program schemes that are usually called Backtracking programs and Branch-and-Bound programs. The derivation consists of a series of transformation steps, specifically algebraic manipulations, on the initial specification until the desired programs are obtained. The well-known notions of linear recursion and tail recursion are extended, for structures, to elementwise linear recursion and elementwise tail recursion; and a transformation between them is derived too

Polar foliations and isoparametric maps

A singular Riemannian foliation $F$ on a complete Riemannian manifold $M$ is called a polar foliation if, for each regular point $p$, there is an immersed submanifold $\Sigma$, called section, that passes through $p$ and that meets all the leaves and always perpendicularly. A typical example of a polar foliation is the partition of $M$ into the orbits of a polar action, i.e., an isometric action with sections. In this work we prove that the leaves of $F$ coincide with the level sets of a smooth map $H: M\to \Sigma$ if $M$ is simply connected. In particular, we have that the orbits of a polar action on a simply connected space are level sets of an isoparametric map. This result extends previous results due to the author and Gorodski, Heintze, Liu and Olmos, Carter and West, and Terng.Comment: 9 pages; The final publication is available at springerlink.com http://www.springerlink.com/content/c72g4q5350g513n1