Parallel implementation of the recurrence method for computing the power-spectral density of thin avalanche photodiodes

A simulation program has been developed to calculate the power-spectral density of thin avalanche photodiodes, which are used in optical networks. The program extends the time-domain analysis of the dead-space multiplication model to compute the autocorrelation function of the APD impulse response. However, the computation requires a large amount of memory space and is very time consuming. We describe our experiences in parallelizing the code using both MPI and OpenMP. Several array partitioning schemes and scheduling policies are implemented and tested Our results show that the OpenMP code is scalable up to 64 processors on an SGI Origin 2000 machine and has small average errors.

Parallel bandwidth characteristics calculations for thin avalanche photodiodes on a SGI Origin 2000 supercomputer

An important factor for high-speed optical communication is the availability of ultrafast and low-noise photodetectors. Among the semiconductor photodetectors that are commonly used in today’s long-haul and metro-area fiber-optic systems, avalanche photodiodes (APDs) are often preferred over p-i-n photodiodes due to their internal gain, which significantly improves the receiver sensitivity and alleviates the need for optical pre-amplification. Unfortunately, the random nature of the very process of carrier impact ionization, which generates the gain, is inherently noisy and results in fluctuations not only in the gain but also in the time response. Recently, a theory characterizing the autocorrelation function of APDs has been developed by us which incorporates the dead-space effect, an effect that is very significant in thin, high-performance APDs. The research extends the time-domain analysis of the dead-space multiplication model to compute the autocorrelation function of the APD impulse response. However, the computation requires a large amount of memory space and is very time consuming. In this research, we describe our experiences in parallelizing the code in MPI and OpenMP using CAPTools. Several array partitioning schemes and scheduling policies are implemented and tested. Our results show that the code is scalable up to 64 processors on a SGI Origin 2000 machine and has small average errors.

Property in body parts and products of the human body

An intriguing question, which until recently had not been directly explored by the courts, is the extent to which English law recognises body parts and products of the human body as property capable of ownership. Although the common law currently recognises no general property in a dead body (and only limited possessory rights in respect of it), this apparent “no-property rule” provides no justification, it is submitted, for denying proprietary status to parts or products of a living human body. The recent decision of the Court of Appeal in Yearworth v. North Bristol NHS Trust ([2009] EWCA Civ 37) lends strong support to the view that genetic material (as the product of a living human body) is capable of ownership, at least in the context of a claim in the tort of negligence and bailment. This article examines the various issues by reference to both English and Commonwealth authority.

Venus infers

These poems mark the fault lines of myth, dream and memory, of a doubled identity emerging from the clash of war, desire and the cacophony of the city. 1974/Dead Sister , a narrative poem with a cast that includes Lewis Carroll’s Alice, Freud’s Dora, the Lady of Shalott, Ophelia, Esther, female cowboys and other deposed goddesses is ‘an autobiography’ of an imaginary dead twin. Alev Adil delineates the traces of a sense of displacement, but while the poems mark those frenetic uncertainties and erasures they celebrate the plenitude of new stories, epistemologies and possibilities born out of falling into fracture (the fracture of memory, gender, identity, culture) more than they mourn any loss. Venus Infers is haunted by the deities of ancient Greek myths and their contemporary manifestations. Eurydice is hiding out in Hackney, sometimes glimpsed on the Jubilee Line; Ariadne remembers her ancient palace as she prowls the endless corridors of a London hotel; Penelope still waits for peace in the ruins of Marash/Varosha. Cyprus often features in these poems, both as a landscape for myth and as a site for contemporary, and contested, memories. [From the Author]

Redefining knowledge in an information world – a polemic

This paper looks at knowledge and information as different forms of the same ideas or "memes". Very different, for knowledge is live, and information is dead. Knowledge is personal, difficult to acquire; information is plentiful, a commodity. Dawkins coined the term meme to refer to a "unit of cultural transmission". I distinguish between forms of the meme that are live knowledge – the internal idea, or imago, and the external transient representation of it, the ephemeron – and those which are permanent information (artefact and permaphemeron). It is a mistake to talk of a "content-free" learning experience, as though content were "just information". Content is knowledge. The point of education is not just to regenerate live knowledge from one generation to the next, it is to extend and add to it through knowledge creation. And knowledge creativity does not operate in a knowledge vacuum. You need ideas to breed ideas.