Maker-Breaker Percolation Games I: Crossing Grids

Motivated by problems in percolation theory, we study the following 2-player positional game. Let $\Lambda_{m \times n}$ be a rectangular grid-graph with $m$ vertices in each row and $n$ vertices in each column. Two players, Maker and Breaker, play in alternating turns. On each of her turns, Maker claims $p$ (as-yet unclaimed) edges of the board $\Lambda_{m \times n}$, while on each of his turns Breaker claims $q$ (as-yet unclaimed) edges of the board and destroys them. Maker wins the game if she manages to claim all the edges of a crossing path joining the left-hand side of the board to its right-hand side, otherwise Breaker wins. We call this game the $(p,q)$-crossing game on $\Lambda_{m \times n}$. Given $m,n\in \mathbb{N}$, for which pairs $(p,q)$ does Maker have a winning strategy for the $(p,q)$-crossing game on $\Lambda_{m \times n}$? The $(1,1)$-case corresponds exactly to the popular game of Bridg-it, which is well understood due to it being a special case of the older Shannon switching game. In this paper, we study the general $(p,q)$-case. Our main result is to establish the following transition: $\bullet$ If $p\geqslant 2q$, then Maker wins the game on arbitrarily long versions of the narrowest board possible, i.e. Maker has a winning strategy for the $(2q, q)$-crossing game on $\Lambda_{m \times(q+1)}$ for any $m\in \mathbb{N}$; $\bullet$ if $p\leqslant 2q-1$, then for every width $n$ of the board, Breaker has a winning strategy for the $(p,q)$-crossing game on $\Lambda_{m \times n}$ for all sufficiently large board-lengths $m$. Our winning strategies in both cases adapt more generally to other grids and crossing games. In addition we pose many new questions and problems.Comment: 29 pages, 7 figure

The spread of antimalarial drug resistance: A mathematical model with practical implications for ACT drug policies

Most malaria-endemic countries are implementing a change in antimalarial drug policy to artemisinin combination therapy (ACT). The impact of different drug choices and implementation strategies is uncertain. A comprehensive model was constructed incorporating important epidemiological and biological factors and used to illustrate the spread of resistance in low and high transmission settings. The model predicts robustly that in low transmission settings drug resistance spreads faster than in high transmission settings, and that in low transmission areas ACTs slows the spread of drug resistance to a partner drug, especially at high coverage rates. This effect decreases exponentially with increasing delay in deploying the ACT and decreasing rates of coverage. A major obstacle to achieving the benefits of high coverage is the current cost of the drugs. This argues strongly for a global subsidy to make ACTs generally available and affordable in endemic areas

Dynein Light Chain 1 Functions as a Cofactor for Post-Transcriptional mRNA Regulation and RNA Granule Assembly

Gene regulation is essential for ensuring maintenance, proliferation, and proper development of a cell. RNA binding proteins (RBPs) regulate gene expression by targeting and binding mRNAs to control their translation and often localize to cytoplasmic assemblies of protein and RNA called RNA granules to facilitate post-transcriptional mRNA regulation. Using C. elegans as a model organism, we report on the function of dynein light chain 1 (DLC-1), a subunit of the dynein motor complex, in post-transcriptional mRNA regulation in the gonad. Previous work suggests that DLC-1 is an RBP cofactor that functions independent of the dynein motor. It is unknown how widespread this regulatory role for DLC-1 may be or what direct interactions between DLC-1 and RBPs make mRNA regulation possible. The work presented in this dissertation suggests that DLC-1 is an important contributor to post-transcriptional mRNA regulation as well as RNA granule assembly. First, we used RNA immunoprecipitation coupled with high throughput sequencing (RIP-seq) to identify the mRNAs associated with DLC-1 through its interaction with RBPs. We found that DLC-1 is involved in post-transcriptional regulation of the oogenic transcriptome and demonstrated that DLC-1-associated transcripts depend on DLC-1 for regulation of their expression in the germline. From this work we identified the RBP OMA-1 as a new interactor of DLC-1 by an in vitro pulldown. Furthermore, we developed a protocol for application of in situ Proximity Ligation Assay (PLA) for use in C. elegans to probe for protein-protein interactions across developmental stages. This allowed us to detect formation of DLC-1/OMA-1 complexes in the gonad. Finally, we used a bioinformatic scan to find additional C. elegans RBPs that might interact with DLC-1. Using in vitro pulldowns, we verified predicted direct interactions between DLC-1 and 4 core RBP components of P granules, which are a subtype of RNA granule. Knockdown or knockout of dlc-1 disrupts embryonic P granule assembly, suggesting that DLC-1 has an important role in this process. As a whole, this work expands upon the alternate and emerging functions of dynein light chains and suggests that cofactors like DLC-1 play critical roles in promoting mRNA regulation

Validity and repeatability of a simple index derived from the short physical activity questionnaire used in the European Prospective Investigation into Cancer and Nutrition (EPIC) study

Original article can be found at: http://journals.cambridge.org/action/displayJournal?jid=PHN Copyright The Authors. DOI: 10.1079/PHN2002439Peer reviewe

Item and Person Characteristics as Predictors of Faking

Applicants may be more motivated to fake than incumbents and may fake more on some items than others. The present study investigated both item and person characteristics as predictors of faking. At the item level, both item transparency and job-relevance were hypothesized to be associated with higher levels of faking. In contrast, item verifiability was hypothesized to be associated with lower levels of faking. At the person level, applicants were expected to have a higher prevalence of faking than incumbents. Data was taken from an existing pool of applicants (n = 507) and incumbents (n = 302) at a customer calling center. The study was performed using a multilevel-logistic regression (MLR) approach to estimating person response curve (PRC) for results for Conscientiousness, Extraversion, and Openness items. None of the item-level results were significant for Conscientiousness, but the analyses found significant item-level effects for Extraversion and Openness. First, item transparency was related to higher levels of faking. Also, individuals were more likely to fake for items of low verifiability than items of high verifiability. Unexpectedly, individuals were more likely to fake for items of low job-relevance than items of high job-relevance. The results for person-level effects showed that applicants exhibited substantial model fit over incumbents, although incumbents appeared to have higher levels of faking than incumbents. The results and implications are discussed

Automated analysis and validation of open chemical data

Methods to automatically extract Open Data from the chemical literature, validate it, and use it to validate theory are examined. Chemical identifiers which assist the automatic location of chemical structures using commercial Web search engines are investigated. The IUPAC International Chemical Idenfitifer (InChI) gives almost 100% recall and precision, though is shown to be too long for present search engines. A combination of InChI and InChIKey, a shorter, fixed-length hash of the InChI string, is concluded to be the best current method of identifying structures. The proportion of published, Open Crystallographic Information Files (CIFs) that are valid with respect to the specification is shown to be improving, and is around 99% in 2007. The error rate in the conversion of valid CIFs to Chemical Markup Language (CML) is less than 0.2%. The machine generation of connection tables from CIFs requires many heuristics, and in some cases it is impossible to deduce the exact connection table. CrystalEye, a fully-automated system for the reformulation of the fragmented crystallographic Web into a structured XML-based repository is described. Published, Open CIFs can be located and aggregated programmatically with almost 100% recall. It is shown that, by converting CIF data to CML, software can be created to use the latest Web standards and technologies to enhance the ability of Web users to browse, find, keep updated, download and reuse the latest published crystallography. A workflow for the high-throughput calculation of solid-state geometry using a semi-empirical method is described. A wide-range of organic and inorganic systems provided by CrystalEye are used to test both the data and the method. Several errors in the method are discovered, many of which can be attributed to the parameterization process. An Open NMR experiment to perform high-throughput prediction of 13C chemical shifts using a GIAO protocol is described. The data and analysis were provided on publicly-available webpages to enable crowdsourcing, which assisted in discovering an error rate of 6.1% in the starting data. The protocol was refined during the work and shown to have an average unsigned error of 2.24ppm for 13C nuclei of small, rigid molecules; comparable to the errors observed elsewhere for general structures using HOSE and Neural Network methods

Identification and Evaluation of Predictors for Learning Success and of Models for Teaching Computer Programming in Contemporary Contexts

Introductory undergraduate computer programming courses are renowned for higher than average failure and withdrawal rates when compared to other subject areas. The closer partnership between higher education and the rapidly expanding digital technology industry, as demonstrated by the establishment of new Degree Apprenticeships in computer science and digital technologies, requires efficient and effective means for teaching programming skills. This research, therefore, aimed to identify reliable predictors of success in learning programming or vulnerability to failure. The research also aimed to evaluate teaching methods and remedial interventions towards recommending a teaching model that supported and engaged learners in contemporary contexts that were relevant to the workplace. Investigation of qualifications designed to prepare students for undergraduate computer science courses revealed that A-level entrants achieved significantly higher programming grades than BTEC students. However, there was little difference between the grades of those with and those without previous qualifications in computing or ICT subjects. Analysis of engagement metrics revealed a strong correlation between extent of co-operation and programming grade, in contrast to a weak correlation between programming grade and code understanding. Further analysis of video recordings, interviews and observational records distinguished between the type of communication that helped peers comprehend tasks and concepts, and other forms of communication that were only concerned with completing tasks. Following the introduction of periodic assessment, essentially converting a single final assessment to three staged summative assessment points, it was found that failing students often pass only one of the three assignment parts. Furthermore, only 10% of those who failed overall had attempted all three assignments. Reasons for failure were attributed to ‘surface’ motivations (such as regulating efforts to achieve a minimum pass of 40%), ineffective working habits or stressful personal circumstances rather than any fundamental difficulty encountered with subject material. A key contribution to pedagogical practice made by this research is to propose an ‘incremental’ teaching model. This model is informed by educational theory and empirical evidence and comprises short cycles of three activities: presenting new topic information, tasking students with a relevant exercise and then demonstrating and discussing the exercise solution. The effectiveness of this model is evidenced by increased engagement, increased quiz scores at the end of each teaching session and increased retention of code knowledge at the end of the course

The impact of narcissistic personality disorder on others: A study of romantic partners and family members

Narcissistic personality disorder (NPD) is a diagnosed mental health disorder that affects up to 6.2% of the population. NPD is known to have a strong interpersonal component, as individuals express their vulnerabilities to others in ways that are challenging. For instance, a person may sometimes seem grandiose and prone to intense hostility, but at other times seem vulnerable and needy, yet difficult to please. However, while the presence of interpersonal dysfunction has been identified for individuals with NPD, little is known about how this is experienced by partners and family members. This thesis presents four original studies on the impact of NPD on romantic partners and family members to progress our understanding of the disorder and improve treatment. Method: The thesis begins with a critical review of existing literature regarding the construct of NPD to determine new research questions to be addressed (Chapter 1). Chapter 2 presents a study of partners and family in a close relationship with someone with NPD (N = 683) to assess levels of grief, burden, coping and mental health. Thematic analysis of a subset of participants\u27 qualitative descriptions of their relative was conducted (N = 436), exploring the characteristics of the NPD relative (chapter 3) and their interpersonal interactions (chapter 4). Finally, some participants (N = 15) were asked to provide detailed narratives comparing their relationships with their relative and with others (chapter 5), to study core conflictual relationship themes (CCRTs). Chapter 6 provides an overview of research findings and outlines implications for the assessment, diagnosis and treatment of individuals with NPD, but also targeted therapeutic supports for partners and family members. Results: Participants living with a relative with NPD were suffering significant psychological symptoms (69% depression, 82% anxiety) and high burden (chapter 2). Levels of symptoms and burden were higher than individuals living with people diagnosed with borderline personality disorder or other severe mental illness. Participant’s descriptions of their relative (chapter 3) included both “grandiose” tendencies (including entitlement, envy and exploitativeness) but also “vulnerable” ones (including hypersensitivity, insecurity and emptiness). The relationship included themes of coercive control (chapter 4), where the relative made challenging physical, verbal, emotional, financial and sexual demands. Fluctuations in idealisation, devaluation, hostility, and dependency were often present in the relationship. Relationship narratives involving relatives with pathological narcissism involved more instances of disharmony, including relatives rejecting, subjugating and attacking behaviours, and participants rejecting and withdrawing behaviours, corresponding with a deactivation of participants attachment system (chapter 5). Conclusion: Living with a person with NPD appears to inflict a considerable psychological toll on those closest to the person. While narcissistic grandiosity, coercive control and interpersonal antagonism may serve to protect the individual who is suffering, these have an insidious effect on partners and family members. Treatments for NPD are limited, with no randomised controlled trials. The findings presented here have two major implications for therapy. First, that the disorder has severe impacts on others, meaning the mental health needs of close relatives should be assessed. Second, that therapists will need specific, targeted support to help them work with individuals with NPD, to help navigate fluctuations of grandiosity and vulnerability in this patient group, sometimes prone to being coercive, controlling and hostile, whilst also presenting as needy and insecure