Bayesian variable selection in structured high-dimensional covariate spaces with applications in genomics

We consider the problem of variable selection in regression modeling in high-dimensional spaces where there is known structure among the covariates. This is an unconventional variable selection problem for two reasons: (1) The dimension of the covariate space is comparable, and often much larger, than the number of subjects in the study, and (2) the covariate space is highly structured, and in some cases it is desirable to incorporate this structural information in to the model building process. We approach this problem through the Bayesian variable selection framework, where we assume that the covariates lie on an undirected graph and formulate an Ising prior on the model space for incorporating structural information. Certain computational and statistical problems arise that are unique to such high-dimensional, structured settings, the most interesting being the phenomenon of phase transitions. We propose theoretical and computational schemes to mitigate these problems. We illustrate our methods on two different graph structures: the linear chain and the regular graph of degree k. Finally, we use our methods to study a specific application in genomics: the modeling of transcription factor binding sites in DNA sequences. © 2010 American Statistical Association.

Iterative inversion of experimental data in weighted spaces

We present iterative algorithms for solving linear inverse problems with discrete data and compare their performances with the method of singular function expansion, in view of applications in optical imaging and particle sizing.

The Use of Singular Systems and other Inversion Methods in Weighted L2- spaces

info:eu-repo/semantics/published

Spaces of observation and obscurity: cinematic prisons of light and dark

In The Eye of Power, Foucault delineated the key concerns surrounding hospital architecture in the latter half of the eighteenth century as being the ‘visibility of bodies, individuals and things'. As such, the ‘new form of hospital' that came to be developed ‘was at once the effect and support of a new type of gaze'. This was a gaze that was not simply concerned with ways of minimising overcrowding or cross-contamination. Rather, this was a surveillance intended to produce knowledge about the pathological bodies contained within the hospital walls. This would then allow for their appropriate classification. Foucault went on to describe how these principles came to be applied to the architecture of prisons. This was exemplified for him in the distinct shape of Bentham's panopticon. This circular design, which has subsequently become an often misused synonym for a contemporary culture of surveillance, was premised on a binary of the seen and the not-seen. An individual observer could stand at the central point of the circle and observe the cells (and their occupants) on the perimeter whilst themselves remaining unseen. The panopticon in its purest form was never constructed, yet it conveys the significance of the production of knowledge through observation that became central to institutional design at this time and modern thought more broadly. What is curious though is that whilst the aim of those late eighteenth century buildings was to produce wellventilated spaces suffused with light, this provoked an interest in its opposite. The gothic movement in literature that was developing in parallel conversely took a ‘fantasy world of stone walls, darkness, hideouts and dungeons…' as its landscape (Vidler, 1992: 162). Curiously, despite these modern developments in prison design, the façade took on these characteristics. The gothic imagination came to describe that unseen world that lay behind the outer wall. This is what Evans refers to as an architectural ‘hoax'. The façade was taken to represent the world within the prison walls and it was the façade that came to inform the popular imagination about what occurred behind it. The rational, modern principles ordering the prison became conflated with the meanings projected by and onto the façade. This confusion of meanings have then been repeated and reenforced in the subsequent representations of the prison. This is of paramount importance since it is the cinematic and televisual representation of the prison, as I argue here and elsewhere, that maintain this erroneous set of meanings, this ‘hoax'.

Safe spaces and sense of identity: views and experiences of lesbian, gay and bisexual young people

Empirical data on the life experiences of contemporary school-age lesbian, gay and bisexual (LGB) young people in Britain remains somewhat sparse. This paper reports the preliminary findings of a study conducted at a recently-initiated LGB youth Summer School. To further an appreciation of issues of concern to today's LGB teenagers, in-depth interviews were conducted with 10 Summer School participants (five female and five male, aged 15-18 years). The aim was to elicit their views and experiences relating to their need for support such as that offered by the Summer School. Themes drawn from participants' interviews are presented. Key issues included: being positioned as different by their majority heterosexual peers; feelings of isolation and loneliness in their peer groups and families; difficulties in finding others like themselves for companionship; and the importance of meeting more LGB people of their own age.

Digital Literacy in Story Spaces

This paper describes a study of digital literacy where the researcher worked with one group of English language arts teacher candidates and one of adolescents, reading and writing hypertext fiction. The findings suggest that the adolescent readers/writers brought a more flexible and multiliterate approach to their digital literacy processes than the teacher candidates.

Hope in the Most Unlikely Spaces: Thawra and the Contemporary Arabic Novel

In the early to mid-twentieth century, many novelists in the Arab world championed Arab nationalism in their literary reflections on the social and political struggles of their countries, depicting these struggles primarily in terms of spatial binaries that pitted the Arab world against the West, even as they imported Western literary models of progress and modernity into their own work. The intense experience of national awakening that infused their writing often placed these authors at a literary disadvantage, for in their literature, all too often the depth and diversity of Arabic cultures and the complexity of socio-political struggles across the Arab world were undermined by restrictive spatial discourses that tended to focus only on particular versions of Arab history and on a seemingly unifying national predicament. Between the Arab defeat of 1967 and the present day, however, an increasing number of Arab authors have turned to less restrictive forms of spatial discourse in search of a language that might offer alternative narratives of hope beyond the predictable, and seemingly thwarted, trajectories of nationalism. This study traces the ways in which contemporary Arab authors from Egypt and the Sudan have endeavoured to re-think and re-define the Arab identity in ever-changing spaces where elements of the local and the global, the traditional and the modern, interact both competitively and harmoniously. I examine the spatial language and the tropes used in three Arabic novels, viewing them through the lens of thawra (revolution) in both its socio-political and artistic manifestations. Linking the manifestations of thawra in each text to different scenes of revolution in the Arab world today, in Chapter Two, I consider how, at a stage when the Sudan of the sixties was both still dealing with colonial withdrawal and struggling to establish itself as a nation-state, the geographical and textual landscapes of Tayeb Salih‟s Season of Migration to the North depict the ongoing dilemma of the Sudanese identity. In Chapter Three, I examine Alaa iii al-Aswany‟s The Yacoubian Building in the context of a socially diseased and politically corrupt Egypt of the nineties: social, political, modern, historical, local, and global elements intertwine in a dizzyingly complex spatial network of associations that sheds light on the complicated reasons behind today‟s Egyptian thawra. In Chapter Four, the final chapter, Gamal al-Ghitani‟s approach to his Egypt in Pyramid Texts drifts far away from Salih‟s anguished Sudan and al-Aswany‟s chaotic Cairo to a realm where thawra manifests itself artistically in a sophisticated spatial language that challenges all forms of spatial hegemony and, consequently, old and new forms of social, political, and cultural oppression in the Arab world.