Incomplete graphical model inference via latent tree aggregation

Graphical network inference is used in many fields such as genomics or ecology to infer the conditional independence structure between variables, from measurements of gene expression or species abundances for instance. In many practical cases, not all variables involved in the network have been observed, and the samples are actually drawn from a distribution where some variables have been marginalized out. This challenges the sparsity assumption commonly made in graphical model inference, since marginalization yields locally dense structures, even when the original network is sparse. We present a procedure for inferring Gaussian graphical models when some variables are unobserved, that accounts both for the influence of missing variables and the low density of the original network. Our model is based on the aggregation of spanning trees, and the estimation procedure on the Expectation-Maximization algorithm. We treat the graph structure and the unobserved nodes as missing variables and compute posterior probabilities of edge appearance. To provide a complete methodology, we also propose several model selection criteria to estimate the number of missing nodes. A simulation study and an illustration flow cytometry data reveal that our method has favorable edge detection properties compared to existing graph inference techniques. The methods are implemented in an R package

Competitive tendering in the Scottish National Health Service Was it compulsory, and did it make a difference?(*)

This paper examines the implementation of competitive tendering in the Scottish National Health Service. Data relating to cleaning, catering and laundering services-- the three services targeted for competitive tendering--are examined. Our analysis suggests that for the first four years the request to market test was largely ignored in Scotland. In 1987 it become a management requirement, and within three years of its fresh start implementation of this policy more than matched the corresponding experience in England.

Sex, Reason, and a Taste for the Absurd

Like much of Richard Posner\u27s best work, Sex and Reason does many things, and for that reason will no doubt attract a large and diverse readership. This heavily footnoted, exhaustively researched, and imminently accessible book is a welcome introduction to the interdisciplinary study of sex. For the lay reader it presents an arresting set of speculations about human sexuality, drawn from the author\u27s evident familiarity with a sizeable library of studies representing at least half a dozen scientific and social scientific disciplines, assembled in a readable and lively way. Of more interest, perhaps, to academicians and social scientists familiar with the literature, the book also proposes an ambitious, counter-intuitive, and sure to be controversial sociobiological argument about the essential nature of sexuality. This argument aims to account for both the universality of some sexual behaviors, on the one hand, and the extraordinary diversity of sexual customs, beliefs, and practices, on the other. Sex and Reason is an attempt by our most prominent rationalist to prove the absolute universality of economic reasoning in human choice and behavior by showing the rationality of our presumably most irrational choices and behaviors: those driven by our sexual urges. Thus, as the author states in his opening remarks, the large purpose of this book is to explain the rationality of our sexual behavior, and thereby limit, if not disprove the Aristotelian dictum, quoted in the book\u27s opening epigram, that [Sexual] pleasures are an impediment to rational deliberation, . . . it is impossible to think about anything while absorbed in them. The author\u27s main target, in other words, is neither liberal nor conservative moralism, but rather the widespread intuition, shared by academicians, legislators, and the lay public alike, that whatever the value of economic reasoning in commercial and maybe even some noncommercial spheres of life, it certainly has no relevance -- no explanatory power -- in controlling behavior and choices so thoroughly irrational -- so emotional, instinctive, biological -- as our sexual inclinations and drives. On the contrary, Posner insists, although forces beyond our control heavily determine our sexual preferences, this hardly distinguishes them from other preferences that are similarly given rather than chosen. Accordingly, the determinism of our sexual preferences hardly disqualifies them from the benefit of dispassionate study and control by the trained economist\u27s eye. I argue in this review that although Posner\u27s descriptive claim about the rationality of our sexual behavior does indeed have an odd ring to it, it is Posner\u27s normative claims -- his rigid insistence on dispassion and neutrality in the study and regulation of sexual choice -- that is ultimately the Achilles\u27 heel of this book. It becomes quickly apparent on even a casual reading that Posner\u27s insistence on moral neutrality goes well beyond his liberal sounding tolerance of deviant sexual preferences and practices. Rather, the moral neutrality Posner advocates requires a studied moral apathy toward a bewildering array of practices, customs, habits, and inclinations that cause inestimable amounts of human suffering and reveal the existence of manifest unjust subordination of large groups of persons -- primarily, women. I suggest that moral neutrality is not the attitude we ought to take toward such behaviors, as either scientists or legislators

General Fragmentation Trees

We show that the genealogy of any self-similar fragmentation process can be encoded in a compact measured real tree. Under some Malthusian hypotheses, we compute the fractal Hausdorff dimension of this tree through the use of a natural measure on the set of its leaves. This generalizes previous work of Haas and Miermont which was restricted to conservative fragmentation processes

Tackling the Minimal Superpermutation Problem

A superpermutation on $n$ symbols is a string that contains each of the $n!$ permutations of the $n$ symbols as a contiguous substring. The shortest superpermutation on $n$ symbols was conjectured to have length $\sum_{i=1}^n i!$. The conjecture had been verified for $n \leq 5$. We disprove it by exhibiting an explicit counterexample for $n=6$. This counterexample was found by encoding the problem as an instance of the (asymmetric) Traveling Salesman Problem, and searching for a solution using a powerful heuristic solver.Comment: 5 page

Playing simplicity: polemical stupidity in the writing of the French Enlightenment

Polemical stupidity - a critical concept drawn from Bakhtin – denotes the strategic refusal to understand. It appears most familiarly in the character of the Fool (like Candide), who genuinely does not understand the world, thus unmasking its incoherence. But in literature it can cover too the stance of the narrator or author (who pretends to misunderstand). It also functions at the levels of genre and style, embracing parody and rewriting in general. It is a dialogic or open form of critical engagement. Though it can be found throughout Western literature, polemical stupidity is most richly characteristic of the writing of the French Enlightenment. This book suggests why, and traces its rise and fall as a discursive practice in the century from Pascal to Rousseau. Early chapters consider the concept itself, its emergence in Pascal's ‘Lettres provinciales’, worldliness and unworldliness, and the new writing of 1660-1700 (critical history to fairy tales). The main part of the book, on the age of Enlightenment itself, contains successive chapters on Regency theatre, Montesquieu's ‘Lettres persanes’, Marivaux, Voltaire, Diderot, and finally Rousseau who will not play

The futures of rural migration in sub-Saharan Africa: A literature review and exploratory essay

In a context where 200 million more people are expected to live in sub-Saharan Africa (SSA) alone by 2050, the question of the futures of SSA rural migration is of crucial importance in a region which so far as remained essentially rural, in spite of a growing urbanization process. The first aim of this paper is to undertake a comprehensive review of the literature on the futures of rural migration in SSA. Drawing from 37 studies it provides a picture of anticipated drivers and migration patterns. It shows also that to our knowledge, rural migration in SSA is still largely an underexplored field of research. The second aim of this paper is therefore to provide some more insights about this question developing an essay drawing from general knowledge about population flows and specific scenario work connecting alternative global world orders and plausible scenarios of rural transformation into three alternative narratives about rural migration in SSA. This anticipatory work, with no predictive intention, provides some elements of thought regarding future migration patterns and briefly discuss governance-related implications

Exploring illness and social care management: comparing consumer perspectives of suffering and the challenges faced by service providers

This thesis as a case study explored the narratives of a convenience sample of four women with the disease known as lupus. The author used an ethnographic approach to investigate how these women coped and how service providers, including carers, met their needs. The author used participant observation in his role as Occupational Therapist (and son) to gain access to this sample. He asked them to keep written diaries about their day-to-day experiences of living with the illness. These diaries were later given to the author to read, study and analyse. Additionally, the author’s personal ethnography as a son was submitted as data for this study. This ethnographic writing centred on the life of one sole informant, his mother, who later died with the disease in hospital. Qualitative data analysis (QDA) techniques with grounded theory origins (Glaser and Strauss 1965,1967 and Charmaz 2007) was used to analyse the data. The techniques comprised of line-by-line analysis and coding, constant comparison of cases, thematic analysis, theoretical sampling and the development of framework tables. The study revealed a range of findings, which were later conceptualised into an ethnographic ontology of lupus. First, people encounter a daily struggle to cope with illness symptoms. Second, there was evidence of poor communication between the hospital ward staff (and carers) and failure for social workers to be the main advisor/counsellor of end of life care needs including missing referrals to hospice services. Health and social care professionals sometimes struggle to provide a basic level of service leading to a “know do” gap. This leads to an inconsistent level of end of life care for the individual and limited support for the identified carers. Narratives in diary form have a role to play in helping clinical teams develop meaningful insights into their life of their patients. Clinical teams in turn need to be forthright enough to develop “death covenants” for all patients (and their carers) with palliative care needs. Developing these tools and including them as intervention turn will lead to more cohesive practices within health and social care (Dean 1996, Dean and Melrose 1996, Mol 2008)