Abstraction-based action ordering in planning

Many planning problems contain collections of symmetric objects, actions and structures which render them difficult to solve efficiently. It has been shown that the detection and exploitation of symmetric structure in planning problems can dramatically reduce the size of the search space and the time taken to find a solution. We present the idea of using an abstraction of the problem domain to reveal symmetric structure and guide the navigation of the search space. We show that this is effective even in domains in which there is little accessible symmetric structure available for pruning. Proactive exploitation represents a flexible and powerfulalternative to the symmetry-breaking strategies exploited in earlier work in planning and CSPs. The notion of almost symmetry is defined and results are presented showing that proactive exploitation of almost symmetry can improve the performance of a heuristic forward search planner

The identification and exploitation of almost symmetry in planning problems

Previous work in symmetry detection for planning has identified symmetries between domain objects and shown how the exploitation of this information can help reduce search at plan time. However these methods are unable to detect symmetries between objects that are almost symmetrical: where the objects must start (or end) in slightly different configurations but for much of the plan their behaviour is equivalent. In the paper we outline a method for identifying such symmetries and discuss how this symmetry information can be positively exploited to help direct search during planning we have implemented this method and integrated it with the FF-v2.3 planner and in the paper we present results of experiments with this approach that demonstrate its potential

Cystic fibrosis mice carrying the missense mutation G551D replicate human genotype phenotype correlations

We have generated a mouse carrying the human G551D mutation in the cystic fibrosis transmembrane conductance regulator gene (CFTR) by a one-step gene targeting procedure. These mutant mice show cystic fibrosis pathology but have a reduced risk of fatal intestinal blockage compared with 'null' mutants, in keeping with the reduced incidence of meconium ileus in G551D patients. The G551D mutant mice show greatly reduced CFTR-related chloride transport, displaying activity intermediate between that of cftr(mlUNC) replacement ('null') and cftr(mlHGU) insertional (residual activity) mutants and equivalent to approximately 4% of wild-type CFTR activity. The long-term survival of these animals should provide an excellent model with which to study cystic fibrosis, and they illustrate the value of mouse models carrying relevant mutations for examining genotype-phenotype correlations

Recurrent Latent Variable Networks for Session-Based Recommendation

In this work, we attempt to ameliorate the impact of data sparsity in the context of session-based recommendation. Specifically, we seek to devise a machine learning mechanism capable of extracting subtle and complex underlying temporal dynamics in the observed session data, so as to inform the recommendation algorithm. To this end, we improve upon systems that utilize deep learning techniques with recurrently connected units; we do so by adopting concepts from the field of Bayesian statistics, namely variational inference. Our proposed approach consists in treating the network recurrent units as stochastic latent variables with a prior distribution imposed over them. On this basis, we proceed to infer corresponding posteriors; these can be used for prediction and recommendation generation, in a way that accounts for the uncertainty in the available sparse training data. To allow for our approach to easily scale to large real-world datasets, we perform inference under an approximate amortized variational inference (AVI) setup, whereby the learned posteriors are parameterized via (conventional) neural networks. We perform an extensive experimental evaluation of our approach using challenging benchmark datasets, and illustrate its superiority over existing state-of-the-art techniques

Morphology and the gradient of a symmetric potential predicts gait transitions of dogs

Gaits and gait transitions play a central role in the movement of animals. Symmetry is thought to govern the structure of the nervous system, and constrain the limb motions of quadrupeds. We quantify the symmetry of dog gaits with respect to combinations of bilateral, fore-aft, and spatio-temporal symmetry groups. We tested the ability of symmetries to model motion capture data of dogs walking, trotting and transitioning between those gaits. Fully symmetric models performed comparably to asymmetric with only a 22% increase in the residual sum of squares and only one-quarter of the parameters. This required adding a spatio-temporal shift representing a lag between fore and hind limbs. Without this shift, the symmetric model residual sum of squares was 1700% larger. This shift is related to (linear regression, n = 5, p = 0.0328) dog morphology. That this symmetry is respected throughout the gaits and transitions indicates that it generalizes outside a single gait. We propose that relative phasing of limb motions can be described by an interaction potential with a symmetric structure. This approach can be extended to the study of interaction of neurodynamic and kinematic variables, providing a system-level model that couples neuronal central pattern generator networks and mechanical models

A cohort study of influences, health outcomes and costs of patients' health-seeking behaviour for minor ailments from primary and emergency care settings

To compare health-related and cost-related outcomes of consultations for symptoms suggestive of minor ailments in emergency departments (EDs), general practices and community pharmacies

Constrained generalized supersymmetries and superparticles with tensorial central charges. A classification

We classify the admissible types of constraint (hermitian, holomorphic, with reality conditions on the bosonic sectors, etc.) for generalized supersymmetries in the presence of complex spinors. We further point out which constrained generalized supersymmetries admit a dual formulation. For both real and complex spinors generalized supersymmetries are constructed and classified as dimensional reductions of supersymmetries from {\em oxidized} space-times (i.e. the maximal space-times associated to $n$-component Clifford irreps). We apply these results to sistematically construct a class of models describing superparticles in presence of bosonic tensorial central charges, deriving the consistency conditions for the existence of the action, as well as the constrained equations of motion. Examples of these models (which, in their twistorial formulation, describe towers of higher-spin particles) were first introduced by Rudychev and Sezgin (for real spinors) and later by Bandos and Lukierski (for complex spinors).Comment: 32 pages, LaTe

Utopian youth justice?

This Context Statement constitutes Part One of a two-part submission towards a PhD by Public Works, Part Two consisting of nine publications in the area of youth crime and youth justice. As these various works were written for distinct purposes and focused on a more diverse group of subjects than would be the case for a conventional PhD, the Context Statement aims to ‘glue’ them together by situating them within a broader political and theoretical context. It also seeks to provide firmer intellectual foundations than was evident in the original works, by reviewing in detail relevant literature, outlining the methods adopted in the studies, subjecting each publication to systematic critique and reflecting on my own development as a researcher. Finally, the Context Statement defines what I consider to be the significant contribution to contemporary analyses of youth justice policy that the public works represent. The Context Statement is organised into five chapters. Chapter 1 introduces the Statement with a short account of how the publications came to be written and of my growing awareness of the need to give the applied work I was doing a more critical edge. Chapter 2 outlines the academic context for the research, reviewing the literature around four broad themes: the victimisation of children and young people; the relationship between schools, school exclusion and youth crime; the links between social exclusion and crime; and the preventative turn in youth Justice policy from the late 1990s. Chapter 3 reflects on the nature, scope and limitations of applied social research and considers different approaches that may fall under this heading, with consideration to their political and theoretical implications. Against this backdrop, it then describes and evaluates the range of methods employed in the studies on which the public works were based. Chapter 4 critically reviews each of the public works in turn, considering their focus, validity, impact and significance, and identifies the continuities between them as well as emergent themes. Chapter 5 concludes by re-situating the key findings from the works within the broader policy and theoretical context outlined in the literature review and demonstrating why, collectively, these public works constitute an original and coherent contribution to knowledge. The public works submitted towards this PhD straddle the semi-connected worlds of youth crime and youth justice. They contribute to a growing appreciation of the victimisation of children amongst criminologists and others, emphasising that victimisation and offending correlate less because of the characteristics of the individuals and families involved than because of the restricting circumstances characteristic of late modern capitalist societies. The analysis of preventative strategies, in particular mentoring, whilst revealing examples of success and plausible explanations for this, also questions the extent to which such ‘solutions’ to the crime problem can ‘work’, given that they are predominantly geared towards changing individuals and so can have little bearing on the disadvantageous social and economic circumstances these individuals face. This said, utopianism may not be the worst thing in an uncertain world

An evaluation of the NCY Trust teenage parenting project

This report presents the findings from an evaluation of the Newham Children and Young People’s (NCY) Trust Teenage Parenting project. Research has demonstrated that teenage parents and their children are disproportionately likely to be NEET (not in education, employment or training) but also that their prospects improve when provided with appropriate support