Poisson multi-Bernoulli conjugate prior for multiple extended object filtering

This paper presents a Poisson multi-Bernoulli mixture (PMBM) conjugate prior for multiple extended object filtering. A Poisson point process is used to describe the existence of yet undetected targets, while a multi-Bernoulli mixture describes the distribution of the targets that have been detected. The prediction and update equations are presented for the standard transition density and measurement likelihood. Both the prediction and the update preserve the PMBM form of the density, and in this sense the PMBM density is a conjugate prior. However, the unknown data associations lead to an intractably large number of terms in the PMBM density, and approximations are necessary for tractability. A gamma Gaussian inverse Wishart implementation is presented, along with methods to handle the data association problem. A simulation study shows that the extended target PMBM filter performs well in comparison to the extended target d-GLMB and LMB filters. An experiment with Lidar data illustrates the benefit of tracking both detected and undetected targets

What factors influence world literacy? is Africa different?

Ninety-five percent of the world’s illiterate people live in developing countries, and about 70 percent are women. Female illiteracy rates are particularly high in Sub-Saharan Africa. In Niger and Burkina Faso, for example, more than 90 percent of women are illiterate. This paper presents a model of literacy. It shows that the main determinants of worldwide literacy are enrollment rates, average years of schooling of adults, and life expectancy at birth. Income has a weak nonlinear effect, negatively affecting literacy until a threshold level of per-capita income of about $2200 a year is reached and positively affecting literacy thereafter. Finally, African countries do not have a significantly higher literacy rate when controlling for other factors.Public Health Promotion,Education Reform and Management,Nonformal Education,PrimaryEducation,Curriculum&Instruction,Primary Education,Gender and Education,Curriculum&Instruction,Education Reform and Management,Nonformal Education

Capital Structure and Political Risk in Asia-Pacific Real Estate Markets

This study investigates the determinants of capital structure decisions by real estate firms, with a specific focus on the impact of political risk on leverage. Using a sample of Asia-Pacific REITs and listed property trusts, we find those firms with properties located in countries characterized by relatively high degrees of political risk, such as political instability, and/or greater uncertainty in the ability to repatriate and monetize profits from international investment activities, employ less debt than their counterparts operating in more politically stable environments. This core finding remains robust to alternative sample selection criteria including the division of the sample into high versus low market-to-book value firms, and also holds within the subset of organizations that are active in raising additional capital in the secondary markets

Childhood obesity and educational attainment : A systematic review

Background This report describes the findings and methods of a systematic review of research which explores the relationship between obesity and educational attainment. It has been conducted at a time of great concern about levels of obesity in the UK, and the negative physical, psychological and social impacts of obesity. Current research suggests that there may be a relationship between obesity and poor educational attainment. It is likely that obesity and poor school performance are elements of a broader picture of inequalities in health and education, whereby disadvantaged socio-economic groups tend to have poorer health and lower levels of education. However, it is possible that other factors influence obesity and attainment, such as gender, discrimination and poor mental and emotional well-being. This systematic review was therefore commissioned to address the question: What do we know about the relationship between childhood obesity and educational attainment, from the research literature? In order that our review might be informed by those closest to observing any interaction between obesity and attainment, we sought the perspectives of teachers and young people to identify the causal pathways that seemed most pertinent to them. Findings Is there a statistical association between obesity and educational attainment? While often conflicting, an overall pattern emerges from the research evidence suggesting that there is a weak negative association between obesity and educational attainment in children and young people; i.e. that higher weight is associated with lower educational attainment. Obesity is also associated with other variables, such as socio-economic status, and when these other variables are taken into consideration, the association between obesity and attainment becomes still weaker, and often loses statistical significance. To what extent does the research evidence explore the influence of the broader determinants of health, and in particular socio-economic position, in explaining any link between obesity and attainment? Place of residence, ethnicity, occupation, gender, religion, education, socio-economic status (SES) and social capital were all explored as potential moderating variables in the included research. Twenty-three of 29 studies used a measure of socio-economic status as a moderating variable. Various factors appear to contribute to low educational attainment to some extent, although given the variation in definitions, analyses and quality of data, it is impossible to point to any causative or definite risk factors. Authors of the included studies have posited theories suggesting that the link between obesity and educational attainment is moderated by individual and societal factors. Does the research evidence support or refute these? Most studies explored the influence of obesity upon attainment. Only two studies examined the influence of attainment upon obesity. Many authors suggested multiple causal pathways, many of which remained untested in their studies. The moderating variables used in statistical analyses of the relationship between obesity and attainment were not consistent with the causal pathways proposed, which is probably a reflection of the constraints imposed upon authors conducting secondary analyses of pre-existing datasets (i.e. they made use of existing variables, rather than collecting their own, tailored data). The most frequently cited factors resulting from obesity and impacting upon educational attainment were poor mental health, stigmatisation and discrimination, disordered sleep, decreased time spent in physical activity and socialising, and absenteeism. Different perspectives on obesity and attainment Few young people initially thought that obesity and educational attainment were associated. However, they considered obesity and educational attainment to be of importance to young people. Young people considered parental influence and circumstances, including family income and poverty, and bullying and emotional health to be the most important factors which might explain an association between obesity and educational attainment. Most teachers said that there was an association between obesity and educational attainment. Bullying, low self-esteem and emotional well-being, poverty and poor diet, and physical activity were commonly cited by teachers as being the most important and credible mediating variables in this association. Teachers also considered gender, ethnicity and parental influence to be important factors. While researchers, teachers and young people identified causal pathways whereby low academic attainment resulted from poor mental and emotional health among obese children and young people, only four studies adjusted for mental and emotional health variables. This may represent a significant divergence in the perspectives of researchers and stakeholders. Alternatively, it may be that in the 23 studies which conducted a secondary analysis of an existing dataset, such data were not available to the authors. Another divergence concerns the impact of reduced participation in sports and social activities. While teachers and young people located this within a broader framework of isolation and lower socialisation suffered by obese children – and thus felt reduced sports participation would result in lower attainment – three studies in the included research proposed a causal pathway in which reduced participation in sports and social activities might lead to increased time spent studying and hence higher attainment