Distributed-memory parallelization of an explicit time-domain volume integral equation solver on Blue Gene/P

Two distributed-memory schemes for efficiently parallelizing the explicit marching-on in-time based solution of the time domain volume integral equation on the IBM Blue Gene/P platform are presented. In the first scheme, each processor stores the time history of all source fields and only the computationally dominant step of the tested field computations is distributed among processors. This scheme requires all-to-all global communications to update the time history of the source fields from the tested fields. In the second scheme, the source fields as well as all steps of the tested field computations are distributed among processors. This scheme requires sequential global communications to update the time history of the distributed source fields from the tested fields. Numerical results demonstrate that both schemes scale well on the IBM Blue Gene/P platform and the memory efficient second scheme allows for the characterization of transient wave interactions on composite structures discretized using three million spatial elements without an acceleration algorithm

Potential acoustic benefits of circulation control rotors

The fundamental aeroacoustic mechanisms responsible for noise generation on a rotating blade are theoretically examined. Their contribution to the overall rotor sound pressure level is predicted. Results from a theory for airfoil trailing edge noise are presented. Modifications and extensions to other source theories are described where it is necessary to account for unique aspects of circulation control (CC) aerodynamics. The circulation control rotor (CCR), as embodied on an X-wing vertical takeoff and landing (VTOL) aircraft, is used as an example for computational purposes, although many of the theoretical results presented are generally applicable to other CC applications (such as low speed rotors, propellers, compressors, and fixed wing aircraft). Using the analytical models, it is shown that the utilization CC aerodynamics theoretically makes possible unprecedented advances in rotor noise reduction. For the X-wing VTOL these reductions appear to be feasible without incurring significant attendant performance and weight penalties

Dracula’s fangs

A preface exploring representations of Dracula on stage and screen

This won’t happen

I lived on site as a Caretaker during this ten month long apocalyptic art project by Tom James and Alex Hartley. This chapter recounts that experience and thinks about the artwork

from the outside

I wrote a site-specific text which was installed on Bloc Project's street-facing billboard

Q.A.Q.?

This chapter is a critical meditation on The child’s guide to knowledge, a book first published in 1825 and reprinted many times throughout the nineteenth century as the work of ‘A lady’. As a catechism, the text is structured as a series of questions and answers that were deployed as a script in schooling young people. The ‘catechistic method’ is critiqued by way of writers discussing eighteenth and nineteenth century poets and novelists, particularly Charles Dickens. Like any scripted interaction, the question and answer format can be characterised as a means of conjuring a response. To what extent this is ventriloquism and to what extent this invites subversion is discussed. Because The child’s guide to knowledge is concerned with teaching children ‘common-place subjects’ that adults already know (such as where saffron is grown, or whether the Romans prized eels), the text is discussed in terms of Antonio Gramsci’s formulation of common sense. This is contrasted with the Foucauldian reading of discourse, which leads to a discussion of the catechistic method in terms of education, discipline and voice. In doing so, the chapter considers Ansgar Allen’s (2014) characterisation of education as wearing a benign mask over its complicity with power and violence. In its scripted, mutable nature, The child’s guide to knowledge is posited as another nineteenth-century precursor to digitality to those already mentioned in Seb Franklin’s (2015) Control. The chapter details references to The child’s guide to knowledge in works by Ezra Pound and James Joyce. This leads to a discussion of the chapter’s themes and ideas in relation to creative writing pedagogy, with particular reference to writing prompts. This is also compared to social media and William Burroughs’ notion of language as a virus. The conclusion considers the means by which The child’s guide to knowledge both breaks and forms silence. Allen, A. (2014) Benign violence: education in and beyond the age of reason, Basingstoke: Palgrave Macmillan. Franklin, Seb (2015) Control, digitality as cultural logic Cambridge, MA: The MIT Press

The role of magnetic anisotropy in spin filter junctions

We have fabricated oxide based spin filter junctions in which we demonstrate that magnetic anisotropy can be used to tune the transport behavior of spin filter junctions. Until recently, spin filters have been largely comprised of polycrystalline materials where the spin filter barrier layer and one of the electrodes are ferromagnetic. These spin filter junctions have relied on the weak magnetic coupling between one ferromagnetic electrode and a barrier layer or the insertion of a nonmagnetic insulating layer in between the spin filter barrier and electrode. We have demonstrated spin filtering behavior in La0.7Sr0.3MnO3/chromite/Fe3O4 junctions without nonmagnetic spacer layers where the interface anisotropy plays a significant role in determining transport behavior. Detailed studies of chemical and magnetic structure at the interfaces indicate that abrupt changes in magnetic anisotropy across the non-isostructural interface is the cause of the significant suppression of junction magnetoresistance in junctions with MnCr2O4 barrier layers.Comment: 7 pages, 7 figure

Induced dicentric chromosome formation promotes genomic rearrangements and tumorigenesis

Chromosomal rearrangements can radically alter gene products and their function, driving tumor formation or progression. However, the molecular origins and evolution of such rearrangements are varied and poorly understood, with cancer cells often containing multiple, complex rearrangements. One mechanism that can lead to genomic rearrangements is the formation of a “dicentric” chromosome containing two functional centromeres. Indeed, such dicentric chromosomes have been observed in cancer cells. Here, we tested the ability of a single dicentric chromosome to contribute to genomic instability and neoplastic conversion in vertebrate cells. We developed a system to transiently and reversibly induce dicentric chromosome formation on a single chromosome with high temporal control. We find that induced dicentric chromosomes are frequently damaged and mis-segregated during mitosis, and that this leads to extensive chromosomal rearrangements including translocations with other chromosomes. Populations of pre-neoplastic cells in which a single dicentric chromosome is induced acquire extensive genomic instability and display hallmarks of cellular transformation including anchorage-independent growth in soft agar. Our results suggest that a single dicentric chromosome could contribute to tumor initiation.Leukemia & Lymphoma Society of America (Scholar Award)National Institute of General Medical Sciences (U.S.) (Grant GM088313)American Cancer Society (Research Scholar Grant 121776