Index k saddles and dividing surfaces in phase space, with applications to isomerization dynamics

In this paper we continue our studies of the phase space geometry and dynamics associated with index k saddles (k > 1) of the potential energy surface. Using normal form theory, we give an explicit formula for a "dividing surface" in phase space, i.e. a co-dimension one surface (within the energy shell) through which all trajectories that "cross" the region of the index k saddle must pass. With a generic non-resonance assumption, the normal form provides k (approximate) integrals that describe the saddle dynamics in a neighborhood of the index k saddle. These integrals provide a symbolic description of all trajectories that pass through a neighborhood of the saddle. We give a parametrization of the dividing surface which is used as the basis for a numerical method to sample the dividing surface. Our techniques are applied to isomerization dynamics on a potential energy surface having 4 minima; two symmetry related pairs of minima are connected by low energy index one saddles, with the pairs themselves connected via higher energy index one saddles and an index two saddle at the origin. We compute and sample the dividing surface and show that our approach enables us to distinguish between concerted crossing ("hilltop crossing") isomerizing trajectories and those trajectories that are not concerted crossing (potentially sequentially isomerizing trajectories). We then consider the effect of additional "bath modes" on the dynamics, which is a four degree-of-freedom system. For this system we show that the normal form and dividing surface can be realized and sampled and that, using the approximate integrals of motion and our symbolic description of trajectories, we are able to choose initial conditions corresponding to concerted crossing isomerizing trajectories and (potentially) sequentially isomerizing trajectories.Comment: 49 pages, 12 figure

Abstinence Only vs. Comprehensive Sex Education: What are the Arguments? What is the Evidence?

Responding to the continuing health threats of HIV, STIs and unplanned pregnancy among young people, the widely respected Institute of Medicine of the National Academy of Sciences recently recommended eliminating congressional, federal, state and local "requirements that public funds be used for abstinence-only education." And surveys consistently show that the public wants schools to deliver strong abstinence messages alongside information about self-protection for young people who find themselves in sexual situations. The vast majority of parents support sex education in the schools, including the provision of information about contraceptive and condom use.Unfortunately, federal policy is grossly out of step with the wishes of most parents and students, as well as the scientific research. Since the early 1980s, Congress has devoted significant resources to abstinence-only programming. Partly as a result of federal policy and funding changes, public schools are increasingly supporting abstinence-only curricula that are less likely to include information about birth control, STD prevention and sexual orientation. The evidence tells us that these trends represent a dangerous disservice to America's younger generation

Playwriting and postcolonialism : identifying the key factors in the development and diminution of playwriting in Ghana 1916-2007

The focus of this thesis is playwriting in Ghana from the colonial era to the in 2007 and the Ghana@50 celebrations which marked fifty years of independence from Britain. Through the analysis of key playtexts produced in this period, which I use as a collective document of Ghana’s cultural history, I seek to uncover the major factors that contributed to the flourishing of playwriting directly post independence and its recent dramatic diminution. Over this time period only a few dozen Ghanaian plays were published and of those only a handful have become known to an international audience. However, collectively they document an intricate relationship between politics and culture within a colonial and then postcolonial society. The story that is revealed by the analysis of that relationship unveils a fascinating trajectory in the development of playwriting in Ghana, and highlights a complex, often over-lapping, interplay between theatre and politics. For this research I have drawn significantly on original interviews with artists and academics. The importance of Ghana as a choice of study lies both in analysing why the current situation exists and how, through that analysis, Ghana’s postcolonial experience speaks to, and questions, dominant trends in postcolonial theory. Through an analysis of the work of colonial and postcolonial playwrights I interrogate the claim of the politician and playwright Mohammed ben-Abdallah that his plays fit within Fanon’s ‘third phase’ of postcolonial artistic expression, and suggest that Ghana’s actual position in terms of postcolonial theory (and the effect of the postcolonial experience on playwrights) is far more nuanced. The findings of this research point towards the historic success of playwriting in Ghana being contingent upon the political promotion of a unitary sense of national identity, a situation that occurred both directly post independence and in the 1980s after a series of military coups. Playwrights’ synchronicity with politics during these periods (compounded by the establishment of institutions and the publishing of play texts as icons of Ghanaian culture) enabled political agendas to shape and influence the creative and performative codes of Ghanaian theatre. This led to the promotion of a strict model of legitimating criteria that simultaneously delegitimised alternative or pluralist voices. I argue that this process problematised playwriting and ultimately contributed to a situation where Ghana boasts strong theatrical institutions, but very few new published plays

The Currency of Art: a collaboration between the Baring Archive and the Graduate School of CCW.

This publication arises from a collaborative project undertaken by The Baring Archive and the Graduate School of CCW (Camberwell College of Arts, Chelsea College of Art and Design and Wimbledon College of Art, three of the constituent colleges of University of the Arts London). In 1995, ING acquired the business of Barings plc, after Barings became insolvent as a result of unauthorized trading. Along with the acquisition of the company came a collection of archival material relating to the long history of Barings, whose origins stretch back to 1717 when John Baring of Bremen settled in Exeter and set up business as a merchant and manufacturer. In 1762, his three sons established the London merchant house of John & Francis Baring & Co., later known as Baring Brothers and, by the nineteenth century, the firm had expanded to become a leading financier for overseas governments and businesses. Documentation and objects relating to the illustrious history of the bank were augmented by portraits – eighteenth and nineteenth century paintings of the Baring family by leading practitioners of the period, such as Thomas Lawrence, Benjamin West, John Linnell, Ambrose McEvoy and William Orpen. From the 1970s onwards, a distinguished collection of water-colours was added to the historical archive, containing works by artists such as Paul Sandby, Francis Towne and David Cox, and Barings, with great discernment, had also accrued an impressive group of modern British artworks to hang on its office walls.Prunella Clough, L.S. Lowry, Paul Nash, Matthew Smith, Stanley Spencer, Keith Vaughan and Carel Weight are just a few of the artists represented. The Currency of Art is one outcome of a collaboration initiated with ING seven years ago. Staff and students from Wimbledon College of Art, and pupils from three of its neighbouring secondary schools, were invited to create new works in response to the painting collection which now hangs in ING’s offices at 60 London Wall. The staff, students and schoolchildren – diverse communities in themselves – brought fresh perspectives, distinct from those of financial historians or more traditional academics, to the collection. Residencies, symposia and workshops generated responses to the paintings, culminating in two exhibitions hosted by ING, re:MAKING and re:INVENTING, whereby the newly created works were hung alongside the originals that had inspired them. This represented an unusual opportunity, given the problems associated with conservation and stewardship that often inhibit such a combination

De Camptown Races

[Verse 1]De camptown ladies sing dis songDoo-dah! Doo-dah!De camptown racetrack five miles longOh! Doo-dah day.I come down here wid my hat caved inDoo-dah! Doo-dah!I go back home wid ma pocket full of tinOh! Doo-dah day. [Chorus]Gwine to run all night, gwine to run all dayI bet my money on a bobtail nag, somebody bet on de bay. [Verse 2]De longtail filly an’ de big black hossDoo-dah! Doo-dah!Dey fly de track an’ dey both cut acrossOh! Doo-dah day.De blind hoss stuck in a big mud holeDoo-dah! Doo-dah!Can’t touch bottom wid a ten foot poleOh! Doo-dah day. [Chorus] [Verse 3]Old mully cow come on to de trackDoo-dah! Doo-dah!De bobtail flung her o’er his backOh! Doo-dah day.Den fly along like a railroad carDoo-dah! Doo-dah!Running a race wid a shooting starOh! Doo-dah day. [Chorus

Neural Attractors and Phonological Grammar

This volume collects three articles which constitute the bulk of my PhD research. The overarching theme of the volume is the role of attractors - a concept from dynamical systems theory – in the neural realization of phonological grammar. The motivation for this line of inquiry begins with the claim that the study of language should provide some insight into the workings of the human mind/brain. Indeed this is one of few mantras shared by linguists of the seemingly irreconcilable “Generative” and “Cognitive” schools (e.g. Chomsky 2002; Lakoff 1988). Given this apparent consensus then, it is perhaps surprising that no breakthrough in our understanding of the brain can yet be attributed to some insight from the study of language. An analysis and critique of this state of affairs is given by Poeppel & Embick (2005), who identify (amongst other things) that we currently have no way of relating the ontologies of linguistics and neuroscience. This Ontological Incommensurability Problem (OIP) can be resolved, they argue, by the use of a Linking Hypothesis, which spells out linguistic computations at the relevant level of algorithmic abstraction, such that the neuroscientist need only find the exact implementations of those algorithms in the brain. If such a hypothesis were sufficiently complete then it could, in principle, predict the kinds of neural configurations required for natural language processing, using linguistic theories as their starting point. In this way, we could finally realize the long sought-after goal of cashing in theories of language for understanding of the human brain. Simultaneously, a Linking Hypothesis also has the potential to unearth lower-level explanations for linguistic phenomena, for example where those explanations might depend on purely neurobiological notions (e.g. neuronal morphology, synaptic density, metabolic efficiency, etc.)

Cultural epidemiology for malaria control in Ghana

Malaria is a threat to more than 40% of the world’s population and responsible for more than 300 million acute cases each year, which resulted in 1.2 million deaths in 2002. Over 80% of the malaria-related morbidity and mortality occur in sub-Saharan Africa with children under five and pregnant women at highest risk. The malaria situation in Ghana is typical of sub-Saharan Africa, where malaria is ranked first among the ten diseases most frequently seen in most health facilities in the country. Due to widespread poverty, however, many households depend on a combination of herbs and overthe- counter drugs, usually consisting of inadequate doses of antimalarials, chiefly chloroquine and analgesics. In Ghana, as in other parts of sub-Saharan Africa, where malaria is due mainly to Plasmodium falciparum and potentially fatal, early and effective treatment saves lives by preventing disease progression to severe malaria. In view of this, prompt recognition and effective timely treatment of malaria is a critical element of global malaria control strategies. The overall goal of this study was to determine the occurrence, distribution, and determinants of MRI experiences, meanings and behaviours, inasmuch as these affect risk, and protective behaviours relevant for intervention to reduce malaria-related morbidity and mortality in children and pregnant women. The study was carried out in two rural communities (Obosomasi, located in the forest vegetation zone, and Galo-Sota, in the coastal savannah zone) in Ghana, over the period from October 2002 to April 2004. This was a cultural epidemiological study employing two-stage data collection strategies. The first stage was ethnographic study, which made use of free listing and rating, participatory mapping, focus group discussions and in-depth interviews to generate relevant local malariarelated illness experiences, meanings and behaviours. The second stage made use of these relevant categories and representations to design EMIC (insiders’ perspective) interviews, which are tools to assess the occurrence, determinants and distributions of these categories to guide appropriate interventions for all segments of the population studied. Results indicate that: Malaria is recognised as a leading health problem in these communities, affecting children and pregnant women more than other segments of the population. Mosquitoes were identifies as the leading causes of malaria-related illness without convulsions, a finding at odds with earlier studies in southern Ghana, indicating changing\ud local perceptions. Local people reported that heat from the sun is a major cause of malaria-related illness without convulsions, and this finding suggests a need for further study to determine the link between heat from the sun and triggers of clinical malaria episodes. Home treatment for malaria-related illness is very common and entails the use of herbal and biomedical medications. The clinic and hospital were preferred sites for treatment of MRI, including convulsions, outside the home, but most patients get there rather late. Convulsions were identified as a component of the malaria-related illness complex, and mosquito bites and febrile malaria episodes were identified as two important causes of MRI with convulsions. This finding was also a departure from most previous reports from sub- Saharan Africa. Despite relating mosquito, malaria and convulsions to one another, local people continue to implicate supernatural forces among causes of convulsions, but explaining that spirits take advantage of malaria attacks to make their mischief. Local healers continue to play an important role in the management of convulsions, but mainly as one aspect of the holistic healing process, involving both rituals to drive away mischievous spirits and biomedical treatments. That is, local healers perform rituals to drive away the spirit causing the convulsions, which paves the way for biomedical treatment and a complete cure. Local healers are also reputed to have ‘medicine’ to protect children from convulsive attacks. Despite the general agreement between the accounts of pregnant women and the general population, there were some significant differences suggesting the need for gender-specific interventions to control malaria-related illness in pregnancy. The recent introduction of intermittent preventive treatment appears responsive to this need, but it may need to be extended as a community programme to achieve the goal of reducing the malaria-related disease burden in pregnancy. Vignette-based interviews evoke responses specifying categories of malaria-related illness experiences, meanings, and behaviours similar to case-based interviews, but with differences in frequencies of reporting these categories. This is the first time that the cultural epidemiology framework has been applied to study the sociocultural aspects of malaria covered in this thesis, and it substantially adds to the growing body of knowledge of the importance of sociocultural factors in malaria control. The implications of the findings for interventions are discussed in individual papers presented in the thesis, and in consisting of a discussion of the overall study and conclusions