Mathematical models of eye movements

This is the author accepted manuscript. The final version is available from [the Institute of Mathematics and its ApplicationsSupported by the BBSRC grant no 36/MMI09774

Landscape Analysis Under Measurement Error

This is the author accepted manuscript. The final version is available from ACM via the DOI in this recordThere are situations where the need for optimisation with a global precision tolerance arises — for example, due to measurement, numerical or evaluation errors in the objective function. In such situations, a global tolerance ε > 0 can be predefined such that two objective values are declared equal if the absolute difference between them is less than or equal to ε. This paper presents an overview of fitness landscape analysis under such conditions. We describe the formulation of common landscape categories in the presence of a global precision tolerance. We then proceed by dis- cussing issues that can emerge as a result of using tolerance, such as the increase in the neutrality of the fitness landscape. To this end, we propose two methods to exhaustively explore plateaus in such application domains — one of which is point-based and the other of which is set-based.Engineering and Physical Sciences Research Council (EPSRC

Effect of seminal plasma on functional integrity of rabbit sperm membranes during storage at 4ºC or freezing

[EN] The effect of semen plasma removal either by simple centrifugation or by separation through a Percoll gradient on the integrity of plasma membranes of rabbit spermatozoa during storage at 4°C and freezing was evaluated in two successive experiments. A modifi ed hypo-osmotic swelling test procedure combined with supravital staining was employed to evaluate simultaneously membrane integrity of head and tail membranes of sperm cells. In the first experiment, the impact of semen plasma on membrane integrity of sperm cells was examined in Tris-citric acid-glucose extender at 4°C for 96 h. The percentage of sperm cells with disintegrated tail and head membranes increased in all groups in correlation with the length of storage. After storage for 96 h, removal of semen plasma, irrespective of the method of removal, resulted in signifi cant increase (P<0.01) in the percentage of sperm cells with disintegrated plasma membranes. The adverse effect of storage and removal of semen plasma was more prominent on the tail membranes, and especially during the fi rst 24 h of the storage period. In the second experiment, the impact of semen plasma on membrane integrity of sperm cells undergoing freezing was examined. A total of three groups were arranged as described in the fi rst experiment, and semen samples were frozen in straws using an extender including acetamide and methyl cellulose. Freezing of semen drastically reduced the percentage of sperm cells with intact plasma membranes in postthaw samples. However, removal of semen plasma, irrespective of the method of removal, did not affect the proportion of sperm cells with intact plasma membranes. In conclusion, the effect of semen plasma on plasma membranes varied signifi cantly relative to the preservation temperature of sperm cells. Although it exerted a protective infl uence during storage at 4°C, no protective impact was monitored during freezing.Aksoy, M.; Cankat Lehimcioglu, N.; Akman, O. (2010). Effect of seminal plasma on functional integrity of rabbit sperm membranes during storage at 4ºC or freezing. World Rabbit Science. 16(1). doi:10.4995/wrs.2008.64216

Robust Optimisation using Voronoi-Based Archive Sampling

Engineering and Physical Sciences Research Council (EPSRC

Robust Multi-Modal Optimisation

Robust and multi-modal optimisation are two important topics that have received significant attention from the evolutionary computation community over the past few years. However, the two topics have usually been investigated independently and there is a lack of work that explores the important intersection between them. This is because there are real-world problems where both formulations are appropriate in combination. For instance, multiple ‘good’ solutions may be sought which are distinct in design space for an engineering problem – where error between the computational model queried during optimisation and the real engineering environment is believed to exist (a common justification for multi-modal optimisation) – but also engineering tolerances may mean a realised design might not exactly match the inputted specification (a robust optimisation problem). This paper conducts a preliminary examination of such intersections and identifies issues that need to be addressed for further advancement in this new area. The paper presents initial benchmark problems and examines the performance of combined state-of-the-art methods from both fields on these problems.This work was supported by the Engineering and Physical Sciences Research Council [grant number EP/N017846/1]

Voronoi-Based Archive Sampling for Robust Optimisation

This is the author accepted manuscript. The final version is available from ACM via the DOI in this recordWe propose a framework for estimating the quality of solutions in a robust optimisation setting by utilising samples from the search history and using MC sampling to approximate a Voronoi tessellation. This is used to determine a new point in the disturbance neighbourhood of a given solution such that – along with the relevant archived points – they form a well-spread distribution, and is also used to weight the archive points to mitigate any selection bias in the neighbourhood history. Our method performs comparably well with existing frameworks when implemented inside a CMA-ES on 9 test problems collected from the literature in 2 and 10 dimensions.This work was supported by the Engineering and Physical Sciences Research Council [grant number EP/N017846/1]

The Brunn-Minkowski inequality and a Minkowski problem for A-harmonic Green's function

Abstract In this article we study two classical problems in convex geometry associated to <m:mi mathvariant="script"

Using criticalities as a heuristic for Answer Set Programming

Answer Set Programming is a new paradigm based on logic programming. The main component of answer set programming is a system that finds the answer sets of logic programs. Generally, systems utilize some heuristics to choose new literals at the choice points. The heuristic used in this process is one of the key factors for the performance of the system. A new heuristic for answer set programming has been developed. This heuristic is inspired by hierarchical planning. The notion of criticality, which was introduced for generating abstraction hierarchies in hierarchical planning, is used in this heuristic. The resulting system (CSMODELS) uses this new heuristic and is based on the system SMODELS. The experimental results show that this new heuristic is promising for answer set programming. CSMODELS generally takes less time than SMODELS to find an answer set

Differential, Tissue-specific, Transcriptional Regulation of Apolipoprotein B Secretion by Transforming Growth Factor β

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