A SURVEY OF LARGE SPACE CHAMBERS

Survey of large space chambers - vacuum chambers to simulate space environmen

Modelling rhizomania in sugar beet

With love and gratitude to my parents, for all their advice and encouragement. Acknowledgements I would like to express my sincere gratitude to Dr. Fowler, for his help and guidance as my supervisor for this dissertation. I would also like to thank Dr. Howison for his support as my supervisor during the earlier part of the year, and Dr. Gilligan and Dr. Truscott for the invaluable discussions. I would like to thank the OCIAM Industrial Fund for funding me this year, and Lincoln College for the delicious food and comfortable accom-modation. My thanks go to Keith Gillow, who has always been helpful with queries about LATEX, and all the sta in the Mathematical Institute and Comput-ing Laboratory. I am very grateful to my parents and brother for their continuing guidanc

Supporting the Success of Honors Commuter Students

This paper will review a variety of ways to support commuter success on campus, specifically for Honors Students. Honors Students typically have an intense workload that expects detailed focus into a variety of specific areas for class purpose as well as an expectance in extra-curricular activities and volunteer work. Because of the high expectations Honors students face, there is a need for universities to provide support networks for students. Universities can support their students in a variety of ways, however specific emphasis needs to be placed on Honors students who commute to campus. The author argues two influential ways that can effectively support Honors students that are transitioning to college and/or continuing college education. The first is an example of tangible support and having a student area for Honors students on campus. These usually manifest themselves as “Honors Lounges” that provide a physical area on a campus specifically for Honors students that isn’t inherently focused on studying or academic activities. The main focus of these Honors spaces is to have a space specifically for Honors which could be the only physical place on campus for Honors students that commute. Resident Honors students have the additional resource of a dorm on campus which functions as “their space” on campus but for commuter students, they are in need of somewhere on campus to call, “theirs”. A more personal approach to providing support for commuter students is having Peer Mentors available to students. Peer Mentors that are Honors students themselves are especially useful because they’re able to empathize with students with the shared experience of being a college Honors student

The use of mixture density networks in the emulation of complex epidemiological individual-based models

Complex, highly-computational, individual-based models are abundant in epidemiology. For epidemics such as macro-parasitic diseases, detailed modelling of human behaviour and pathogen life-cycle are required in order to produce accurate results. This can often lead to models that are computationally-expensive to analyse and perform model fitting, and often require many simulation runs in order to build up sufficient statistics. Emulation can provide a more computationally-efficient output of the individual-based model, by approximating it using a statistical model. Previous work has used Gaussian processes (GPs) in order to achieve this, but these can not deal with multi-modal, heavy-tailed, or discrete distributions. Here, we introduce the concept of a mixture density network (MDN) in its application in the emulation of epidemiological models. MDNs incorporate both a mixture model and a neural network to provide a flexible tool for emulating a variety of models and outputs. We develop an MDN emulation methodology and demonstrate its use on a number of simple models incorporating both normal, gamma and beta distribution outputs. We then explore its use on the stochastic SIR model to predict the final size distribution and infection dynamics. MDNs have the potential to faithfully reproduce multiple outputs of an individual-based model and allow for rapid analysis from a range of users. As such, an open-access library of the method has been released alongside this manuscript

Helminth control : more questions than answers

Soil transmitted helminths (STH) and schistosomiasis (SCH) have been recognised as important diseases for decades. Diagnostics, treatments and understanding were accrued throughout the 20th century, and reached the point where control and elimination appeared to be primarily a matter of implementation of mass drug administration (MDA) programmes [1]. However, in 2015, both STH and SCH remain global health problems, so perhaps we do not have the right tools, or we are not applying them effectively. To our knowledge, MDA for STH and SCH has never been demonstrated to eliminate infection without concomitant economic development. What are we missing

Simple approximations for epidemics with exponential and fixed infectious periods

Analytical approximations have generated many insights into the dynamics of epidemics, but there is only one well-known approximation which describes the dynamics of the whole epidemic. In addition, most of the well-known approximations for different aspects of the dynamics are for the classic susceptible–infected–recovered model, in which the infectious period is exponentially distributed. Whilst this assumption is useful, it is somewhat unrealistic. Equally reasonable assumptions are that the infectious period is finite and fixed or that there is a distribution of infectious periods centred round a nonzero mean. We investigate the effect of these different assumptions on the dynamics of the epidemic by deriving approximations to the whole epidemic curve. We show how the well-known sech-squared approximation for the infective population in ‘weak’ epidemics (where the basic reproduction rate R0≈1) can be extended to the case of an arbitrary distribution of infectious periods having finite second moment, including as examples fixed and gamma-distributed infectious periods. Further, we show how to approximate the time course of a ‘strong’ epidemic, where R0≫1, demonstrating the importance of estimating the infectious period distribution early in an epidemic

The dynamics of Ascaris lumbricoides infections

The Anderson–May model of human parasite infections and specifically that for the intestinal worm Ascaris lumbricoides is reconsidered, with a view to deriving the observed characteristic negative binomial distribution which is frequently found in human communities. The means to obtaining this result lies in reformulating the continuous Anderson–May model as a stochastic process involving two essential populations, the density of mature worms in the gut, and the density of mature eggs in the environment. The resulting partial differential equation for the generating function of the joint probability distribution of eggs and worms can be partially solved in the appropriate limit where the worm lifetime is much greater than that of the mature eggs in the environment. Allowing for a mean field nonlinearity, and for egg immigration from neighbouring communities, a negative binomial worm distribution can be predicted, whose parameters are determined by those in the continuous Anderson–May model; this result assumes no variability in predisposition to the infection

How effective is school-based deworming for the community-wide control of soil-transmitted helminths?

Background: The London Declaration on neglected tropical diseases was based in part on a new World Health Organization roadmap to “sustain, expand and extend drug access programmes to ensure the necessary supply of drugs and other interventions to help control by 2020”. Large drug donations from the pharmaceutical industry form the backbone to this aim, especially for soil-transmitted helminths (STHs) raising the question of how best to use these resources. Deworming for STHs is often targeted at school children because they are at greatest risk of morbidity and because it is remarkably cost-effective. However, the impact of school-based deworming on transmission in the wider community remains unclear. Methods: We first estimate the proportion of parasites targeted by school-based deworming using demography, school enrolment, and data from a small number of example settings where age-specific intensity of infection (either worms or eggs) has been measured for all ages. We also use transmission models to investigate the potential impact of this coverage on transmission for different mixing scenarios. Principal Findings: In the example settings <30% of the population are 5 to <15 years old. Combining this demography with the infection age-intensity profile we estimate that in one setting school children output as little as 15% of hookworm eggs, whereas in another setting they harbour up to 50% of Ascaris lumbricoides worms (the highest proportion of parasites for our examples). In addition, it is estimated that from 40–70% of these children are enrolled at school. Conclusions: These estimates suggest that, whilst school-based programmes have many important benefits, the proportion of infective stages targeted by school-based deworming may be limited, particularly where hookworm predominates. We discuss the consequences for transmission for a range of scenarios, including when infective stages deposited by children are more likely to contribute to transmission than those from adults