Studies directed towards the synthesis of (-)-Ebelactone-A

This thesis describes work concerning the total synthesis of ebelactone-a 16, and in particular the synthesis of one of the retrosynthetic fragments (fragment A 20) and its coupling to the combined fragment BC 115 formed from the other two. We repeated the synthesis of enantiomerically enriched 20 devised by Williams, employing a Mukaiyama aldol reaction directed by Oppolzer's sultam to establish the anti-anti stereotriad of the fragment. We modelled the coupling of this to 115 using isobutyraldehyde in place of 20 and vinyl iodide 133 in place of 115, and verified that the Nozaki-Kishi method using chromium(II) chloride and catalytic nickel(II) chloride was effective. By this method, we successfully coupled 133 to 20. Model work was unsuccessful in establishing a methodology for removing the hydroxy group from alcohols 188/189 without disrupting either the position or geometry of the adjacent C=C bond. We also established a completely new route to fragment A, utilising the features of organosilicon chemistry to control the stereochemistry. An intermediate 213 containing two different silyl groups, in which we hoped to transform one selectively into a hydroxy group with retention of configuration by Fleming's method, proved too unstable for synthesis, but we were able to modify the route and produce alcohol 254 in enantiomerically pure form (Oppolzer's sultam was once again used as the chiral auxiliary), and we expect future workers to be able to take this through to fragment A. See attached file abstract.pdf for related images of the the molecular structure

A Challenge Set Approach to Evaluating Machine Translation

Neural machine translation represents an exciting leap forward in translation quality. But what longstanding weaknesses does it resolve, and which remain? We address these questions with a challenge set approach to translation evaluation and error analysis. A challenge set consists of a small set of sentences, each hand-designed to probe a system's capacity to bridge a particular structural divergence between languages. To exemplify this approach, we present an English-French challenge set, and use it to analyze phrase-based and neural systems. The resulting analysis provides not only a more fine-grained picture of the strengths of neural systems, but also insight into which linguistic phenomena remain out of reach.Comment: EMNLP 2017. 28 pages, including appendix. Machine readable data included in a separate file. This version corrects typos in the challenge se

‘Can’t you just tell us the rule?’: teaching procedures relationally

It is now almost 40 years since Skemp’s (1976) seminal division of understanding into ‘instrumental’ and ‘relational’ categories, yet the current political direction of mathematics education in the UK is decidedly towards the traditional teaching of ‘standard algorithms’ (DfE, 2013). In this research paper, I draw on a lively staffroom discussion about different approaches to the teaching of quadratic equations, in which one method used was derided as ‘a trick’. From this, I discuss reasons why certain mathematical processes are often regarded as inherently and irretrievably ‘procedural’. Informed by recent theoretical interpretations of procedural and conceptual learning in mathematics, which increasingly stress their intertwining and iterative relationship(Star, 2005; Baroody, Feil and Johnson, 2007; Star, 2007; Kieran, 2013), I make a case that stigmatising particular methods and censoring their use may deny students valuable opportunities to make sense of mathematics. I argue instead that encouraging students to take a critical stance regarding the details and the value of the procedures that they encounter can cultivate in them a deeper awareness of mathematical connections and a more empowered sense of ownership over their mathematics

‘Can’t you just tell us the rule?’: teaching procedures relationally

It is now almost 40 years since Skemp’s (1976) seminal division of understanding into ‘instrumental’ and ‘relational’ categories, yet the current political direction of mathematics education in the UK is decidedly towards the traditional teaching of ‘standard algorithms’ (DfE, 2013). In this research paper, I draw on a lively staffroom discussion about different approaches to the teaching of quadratic equations, in which one method used was derided as ‘a trick’. From this, I discuss reasons why certain mathematical processes are often regarded as inherently and irretrievably ‘procedural’. Informed by recent theoretical interpretations of procedural and conceptual learning in mathematics, which increasingly stress their intertwining and iterative relationship(Star, 2005; Baroody, Feil and Johnson, 2007; Star, 2007; Kieran, 2013), I make a case that stigmatising particular methods and censoring their use may deny students valuable opportunities to make sense of mathematics. I argue instead that encouraging students to take a critical stance regarding the details and the value of the procedures that they encounter can cultivate in them a deeper awareness of mathematical connections and a more empowered sense of ownership over their mathematics

Getting goose bumps about teaching evolution

Colin Foster thinks that creationist claims can provide a good opportunity in the science classroom for examining the evidence for evolutio

Expression polygons

A problem-solving task can generate extensive opportunities for developing mathematical fluency in solving linear equations

Minimal interventions in the teaching of mathematics

This paper addresses ways in which mathematics pedagogy can benefit from insights gleaned from counselling. Person-centred counselling stresses the value of genuineness, warm empathetic listening and minimal intervention to support people in solving their own problems and developing increased autonomy. Such an approach contrasts starkly with the much more directive and leading interventions often made by mathematics teachers in the classroom. In this position paper I argue that minimal teacher interventions are a powerful way to support students in their learning of mathematics. Drawing on the interplay between a mathematics teacher’s responsibility to teach mathematics and their duty to support students pastorally, I argue that such an approach builds on skills that teachers already possess and has considerable potential to enhance students’ healthy mathematical development

Getting goose bumps about teaching evolution

Colin Foster thinks that creationist claims can provide a good opportunity in the science classroom for examining the evidence for evolutio

Discovery and Correction of Bias in Precision Landmark Location

Precision Landmark Location (PLL) estimation is an integral part of 3D motion tracking. Circular landmark location estimation is one method of PLL. Current methods of estimation lead to systematic errors with a magnitude of up to .02 pixels. Estimation inaccuracies of this magnitude lead to unacceptable errors in depth measurement, the largest source of error. In the scope of this thesis, inadequacies in circular landmark location are uncovered and techniques to correct these errors are analyzed, tested, and demonstrated. Deviations in simulated images are seen to be reduced by a factor of three and the variances of real-world data were reduced by half. This thesis predicts and observes increased accuracy in the 3D motion tracking technology