The Consequences of Teenage Childbearing

We examine the effect of teenage childbearing on the adult outcomes of a sample of women who gave birth, miscarried or had an abortion as teenagers. If miscarriages are (conditionally) random, then if all miscarriages occur before teenagers can obtain abortions, using the absence of a miscarriage as an instrument for a live birth provides a consistent estimate of the effect of teenage motherhood on women who give birth. If all abortions occur before any miscarriage can occur, OLS on the sample of women who either have a live birth or miscarry provides an unbiased estimate of this effect. Under reasonable assumptions, IV underestimates and OLS overestimates the effect of teenage motherhood on adult outcomes. For a variety of outcomes, the two estimates provide a narrow bound on the effect of teenage motherhood on adult outcomes and which is relatively modest. The bounds can also be combined to provide consistent estimates of the effects of teen motherhood. These effects are generally adverse but modest.

Phantom distribution functions for some stationary sequences

The notion of a phantom distribution function (phdf) was introduced by O'Brien (1987). We show that the existence of a phdf is a quite common phenomenon for stationary weakly dependent sequences. It is proved that any $\alpha$-mixing stationary sequence with continuous marginals admits a continuous phdf. Sufficient conditions are given for stationary sequences exhibiting weak dependence, what allows the use of attractive models beyond mixing. The case of discontinuous marginals is also discussed for $\alpha$-mixing. Special attention is paid to examples of processes which admit a continuous phantom distribution function while their extremal index is zero. We show that Asmussen (1998) and Roberts et al. (2006) provide natural examples of such processes. We also construct a non-ergodic stationary process of this type

The ‘Prevent Duty’ (Counter Terrorism and Security Act 2015) and its impact on English secondary schools and colleges: A view from Leadership

In July 2015, a legal duty, popularly referred to as the ‘Prevent Duty’, came into force requiring that ‘specified authorities ’in England, which included schools, show ‘due regard to the need to prevent people from being drawn into terrorism’. Prevent, developed by the Home Office in 2003 outside of full public scrutiny, and only fully operationalised following the 7 July 2005 London bombings, has consistently been the most contentious element of the UK Government counter terrorist strategy CONTEST. An examination of the literature about the development and impact of the ‘Prevent duty ’ and on educational institutions showed a lack of research on how the Duty has been received, appropriated, and implemented by school and college leaders. There are studies on the ‘Prevent duty’ and teachers but not specifically on school leaders. This led to the key research question of the thesis: How has the ‘Prevent duty’ been interpreted and enacted in selected secondary schools and colleges in England by school and college leaders? Data was collected through face to face, recorded, semi-structured interviews with school leaders in a range of schools and colleges in three geographical locations, Greater Manchester, London and the South, Kent, and Sussex. This was augmented by relevant document analysis of school policies. Drawing upon Stephen J. Ball’s work the thesis analyses policy enactment in this case of a contemporary statutory education policy. Applying Foucault’s toolbox of methods, concepts and perspectives as a theoretical lens, the thesis seeks to make sense of policy, leadership, and policy enactment within the phase of ‘muscular liberalism’ and within the global context of an ‘Age of Anger’. The data revealed different views and responses to the ‘Prevent duty’ by school leaders, some positive some critical; the over-arching influence of safeguarding; the rise of ‘securitisation 'in education; the growth of the ‘responsibilisation’ of school leaders; the surprising effects on free speech; the ongoing tension between school leaders ’autonomy and accountability; school leaders ’ agency as ‘sense-makers ’in enacting policy and the need to reconsider school leaders ’ professionalism and their training both in relation to the ‘Prevent duty’ and their wider role. The significance of this study is that it informs our theoretical understanding of the ’Prevent duty’, policy enactment and school and college leadership and provides important empirical data as well as key recommendations for policy makers, school leaders and educationalists moving forward designing and implementing counter terrorism policies for schools and colleges

Structure of a translocation signal domain mediating conjugative transfer by Type IV secretion systems

Relaxases are proteins responsible for the transfer of plasmid and chromosomal DNA from one bacterium to another during conjugation. They covalently react with a specific phosphodiester bond within DNA origin of transfer sequences, forming a nucleo-protein complex which is subsequently recruited for transport by a plasmid-encoded type IV secretion system. In previous work we identified the targeting translocation signals presented by the conjugative relaxase TraI of plasmid R1. Here we report the structure of TraI translocation signal TSA. In contrast to known translocation signals we show that TSA is an independent folding unit and thus forms a bona fide structural domain. This domain can be further divided into three sub-domains with striking structural homology with helicase sub-domains of the SF1B family. We also show that TSA is part of a larger vestigial helicase domain which has lost its helicase activity but not its single-stranded DNA binding capability. Finally, we further delineate the binding site responsible for translocation activity of TSA by targeting single residues for mutations. Overall, this study provides the first evidence that translocation signals can be part of larger structural scaffolds, overlapping with translocation-independent activities

Galois groups of multivariate Tutte polynomials

The multivariate Tutte polynomial $\hat Z_M$ of a matroid $M$ is a generalization of the standard two-variable version, obtained by assigning a separate variable $v_e$ to each element $e$ of the ground set $E$. It encodes the full structure of $M$. Let \bv = \{v_e\}_{e\in E}, let $K$ be an arbitrary field, and suppose $M$ is connected. We show that $\hat Z_M$ is irreducible over K(\bv), and give three self-contained proofs that the Galois group of $\hat Z_M$ over K(\bv) is the symmetric group of degree $n$, where $n$ is the rank of $M$. An immediate consequence of this result is that the Galois group of the multivariate Tutte polynomial of any matroid is a direct product of symmetric groups. Finally, we conjecture a similar result for the standard Tutte polynomial of a connected matroid.Comment: 8 pages, final version, to appear in J. Alg. Comb. Substantial revisions, including the addition of two alternative proofs of the main resul

Short-term traffic prediction using physics-aware neural networks

In this work, we propose an algorithm performing short-termpredictions of the flow and speed of vehicles on a stretch of road, using past measurements of these quantities. This algorithm is based on a physics-aware recurrent neural network. Adiscretization of a macroscopic traffic flowmodel (using the so-called Traffic Reaction Model) is embedded in the architecture of the network and yields traffic state estimations and predictions for the flow and speed of vehicles, which are physically-constrained by the macroscopic traffic flow model and based on estimated and predicted space-time dependent traffic parameters. These parameters are themselves obtained using a succession of LSTM recurrent neural networks. The algorithm is tested on raw flow measurements obtained from loop detectors

Soldier’s beliefs in abstinence before and after the implementation of a novel army nicotine-free policy

United States Army soldiers have used tobacco for decades1 despite known health risks associated with these products.2 Material connections between the tobacco industry and the military during the early part of the 20th century, coupled with pervasive advertising images of soldiers using tobacco during combat, served to promote tobacco use among young recruits entering training.3 A variety of policieshave been instituted during the training period, to varied and sometimes suboptimal effect.4 Currently, tobacco (defined as any non-therapeutic nicotine product) is banned during basic combat training (BCT), the first phase of training in a soldier’s career, which lasts 10 weeks. It is allowed in the longer subsequent advanced individual training (AIT), during which soldiers learn their military occupationspecialty. Trainee soldiers in an AIT aviation battalion on Fort Eustis in Virginia previously reported a reduction in overall tobacco use following BCT,5 prompting a decision to institute a proposed nicotine-free policy during AIT, which lasts approximately 3–6 months. This study aimed to determine if the AIT nicotine-free policy implementation process would change the tobacco user’s intentionto remain abstinent following AIT, when tobacco use would not be restricted

The financial burden of juvenile idiopathic arthritis: A Nova Scotia experience

Background: Juvenile idiopathic arthritis (JIA) is the most common childhood rheumatic illness. There is little published data on the financial burden of this illness. The primary objective of this study was to determine the annual costs borne by families of a child with JIA living in Nova Scotia (NS).Methods: All families in NS with a child followed in the Pediatric Rheumatology Clinic at the Izaak Walton Killam Health Centre (IWK) in 2009 were mailed a self-report questionnaire. The questionnaire evaluated disease related costs, gross household income and perceived financial burden. Dillman\u27s method was used to optimize return rates. Descriptive statistics were used to summarize results. Spearman\u27s correlation coefficient was used to assess the relationship of distance from the IWK and cost. The Mann-Whitney U test was used to compare median costs between groups.Results: Of 172 possible respondents, we received 54 completed questionnaires and 11 blank questionnaires (overall response rate 31.4%). Approximately one third (35.9%) of parents rated the financial burden as moderate or large and 36% rated financial resources available as poor. The median annual total cost per patient was $619.50 CAD (range 0,$5535) which was a median 0.7% (range 0, 37%) of gross household incomes. The largest expense for families was visit related costs. There was not a significant relationship between total annual costs and distance from the IWK (rs = 0.18, P = 0.2). Families of a child with oligoarthritis had significantly lower costs than the families of a child with another subtype of JIA ($359.00 CAD vs.$877.00 CAD, P = 0.02).Conclusions: The costs associated with having a child with JIA in NS are on average modest, but may be considerable for some families. Oligoarticular JIA is associated with smaller costs. Many families perceive the burden to be at least moderate and the availability of financial resources to be poor. Supports should be targeted to those families most in need. © 2013 Ens et al.; licensee BioMed Central Ltd

The financial burden of juvenile idiopathic arthritis: A Nova Scotia experience

Background: Juvenile idiopathic arthritis (JIA) is the most common childhood rheumatic illness. There is little published data on the financial burden of this illness. The primary objective of this study was to determine the annual costs borne by families of a child with JIA living in Nova Scotia (NS).Methods: All families in NS with a child followed in the Pediatric Rheumatology Clinic at the Izaak Walton Killam Health Centre (IWK) in 2009 were mailed a self-report questionnaire. The questionnaire evaluated disease related costs, gross household income and perceived financial burden. Dillman\u27s method was used to optimize return rates. Descriptive statistics were used to summarize results. Spearman\u27s correlation coefficient was used to assess the relationship of distance from the IWK and cost. The Mann-Whitney U test was used to compare median costs between groups.Results: Of 172 possible respondents, we received 54 completed questionnaires and 11 blank questionnaires (overall response rate 31.4%). Approximately one third (35.9%) of parents rated the financial burden as moderate or large and 36% rated financial resources available as poor. The median annual total cost per patient was $619.50 CAD (range 0,$5535) which was a median 0.7% (range 0, 37%) of gross household incomes. The largest expense for families was visit related costs. There was not a significant relationship between total annual costs and distance from the IWK (rs = 0.18, P = 0.2). Families of a child with oligoarthritis had significantly lower costs than the families of a child with another subtype of JIA ($359.00 CAD vs.$877.00 CAD, P = 0.02).Conclusions: The costs associated with having a child with JIA in NS are on average modest, but may be considerable for some families. Oligoarticular JIA is associated with smaller costs. Many families perceive the burden to be at least moderate and the availability of financial resources to be poor. Supports should be targeted to those families most in need. © 2013 Ens et al.; licensee BioMed Central Ltd

Parameter and density estimation from real-world traffic data: A kinetic compartmental approach

The main motivation of this work is to assess the validity of a LWR traffic flow model to model measurements obtained from trajectory data, and propose extensions of this model to improve it. A formulation for a discrete dynamical system is proposed aiming at reproducing the evolution in time of the density of vehicles along a road, as observed in the measurements. This system is formulated as a chemical reaction network where road cells are interpreted as compartments, the transfer of vehicles from one cell to the other is seen as a chemical reaction between adjacent compartment and the density of vehicles is seen as a concentration of reactant. Several degrees of flexibility on the parameters of this system, which basically consist of the reaction rates between the compartments, can be considered: a constant value or a function depending on time and/or space. Density measurements coming from trajectory data are then interpreted as observations of the states of this system at consecutive times. Optimal reaction rates for the system are then obtained by minimizing the discrepancy between the output of the system and the state measurements. This approach was tested both on simulated and real data, proved successful in recreating the complexity of traffic flows despite the assumptions on the flux-density relation