Active Vision Strategies in Predation

Visual predation requires precise and accurate behaviour, for which many predators have evolved excellent visual skills. However, an animal's visual abilities are greatly affected by how it moves its eyes, known as active vision. Insects have immobile eyes but can direct their gaze by moving their heads and bodies. This thesis examines three predatory insects with different predatory strategies, to understand the extent to which active vision can be used in predation. The first experimental chapter considers the African praying mantid, Sphodromantis lineola. Praying mantids are stationary terrestrial predators, which use their extremely mobile necks to visually track prey until it is within reach. By using statistical models, we identified what factors elicited strikes and, importantly, their success rate. The timing of head movements greatly increased the chances of strike success, with earlier movements increasing the success rate. The second experimental chapter addresses how darting robber flies, Psilonyx annulatus, aerially attack static prey. Prior to attacking, darting robber flies translate their body around a central point, assessing their prey. After assessment, they attack from a position correlated with the target's absolute size, not its angular size. Prey is beyond the robber fly's stereopsis range during the period of assessment. Assessments of differently sized targets have similarities with the behaviour exhibited by jumping insects, which use motion parallax, a form of active vision, to assess jump distance, suggesting darting robber flies also use motion parallax to predate. The final experimental chapter considers killer flies, Coenosia attenuata, which chase moving targets aerially. Killer flies use a combination of gravity and wing acceleration to increase their speed when chasing prey from above. This increased speed restricts the flies' ability to steer. However, killer flies create strong looming stimuli which may trigger their prey to produce evasive manoeuvres, thereby slowing down. Moreover, by travelling faster towards their prey, killer flies may avoid losing track of it, a real danger when chasing moving prey with low- resolution eyes potentially avoided thanks to active vision. By employing active vision, each of the predators considered can achieve impressive performances, despite relying on very different strategies to capture prey. The use of active vision can increase the success of already excellent visual predators and improve the performance of predator with limited vision. However, active vision can also substantially alter predatory behaviour, leading to a trade- off between the advantages in visual perception active vision can bring and the disadvantage in behavioural efficiency of active vision strategies

Subgraphs and Colourability of Locatable Graphs

We study a game of pursuit and evasion introduced by Seager in 2012, in which a cop searches the robber from outside the graph, using distance queries. A graph on which the cop wins is called locatable. In her original paper, Seager asked whether there exists a characterisation of the graph property of locatable graphs by either forbidden or forbidden induced subgraphs, both of which we answer in the negative. We then proceed to show that such a characterisation does exist for graphs of diameter at most 2, stating it explicitly, and note that this is not true for higher diameter. Exploring a different direction of topic, we also start research in the direction of colourability of locatable graphs, we also show that every locatable graph is 4-colourable, but not necessarily 3-colourable.Comment: 25 page

A probabilistic version of the game of Zombies and Survivors on graphs

We consider a new probabilistic graph searching game played on graphs, inspired by the familiar game of Cops and Robbers. In Zombies and Survivors, a set of zombies attempts to eat a lone survivor loose on a given graph. The zombies randomly choose their initial location, and during the course of the game, move directly toward the survivor. At each round, they move to the neighbouring vertex that minimizes the distance to the survivor; if there is more than one such vertex, then they choose one uniformly at random. The survivor attempts to escape from the zombies by moving to a neighbouring vertex or staying on his current vertex. The zombies win if eventually one of them eats the survivor by landing on their vertex; otherwise, the survivor wins. The zombie number of a graph is the minimum number of zombies needed to play such that the probability that they win is strictly greater than 1/2. We present asymptotic results for the zombie numbers of several graph families, such as cycles, hypercubes, incidence graphs of projective planes, and Cartesian and toroidal grids

USA v. Robinson

USDC for the Eastern District of Pennsylvani

State of Utah v. Jared Casanova : Brief of Appellee

AN APPEAL FROM CONVICTIONS FOR AGGRAVATED ROBBERY, A FIRST DEGREE FELONY, IN VIOLATION OF UTAH CODE ANN. § 76- 6-302 (1999), ATTEMPTED THEFT, A THIRD DEGREE FELONY, IN VIOLATION OF UTAH CODE ANN. § 76-6-404 (1999), FAILURE TO RESPOND TO AN OFFICER\u27S SIGNAL TO STOP, A THIRD DEGREE FELONY, IN VIOLATION OF UTAH CODE ANN. § 41-6-13.5 (SUPP. 1999), AND ATTEMPTED ESCAPE, A CLASS A MISDEMEANOR, IN VIOLATION OF UTAH CODE ANN. § 76-8-309 (1999), IN THE THIRD JUDICIAL DISTRICT COURT OF UTAH, SALT LAKE COUNTY, THE HONORABLE ROBIN W. REESE PRESIDIN

Lincoln and Liberty, Too

“The world has never had a good definition of the word liberty,” Abraham Lincoln said in 1864. And surely, from Lincoln of all people, that statement must come as a surprise, and for two reasons. In the first place, no one in American history might be said to have been a more shining example of liberty than Abraham Lincoln. Not only had he exercised liberty to its fullest extent, rising from poverty and obscurity to become the 16th president of the United States, but in the process he became the Great Emancipator of over three million slaves, and if anyone should have been in a position to know what liberty meant, it was Lincoln. [excerpt

Patrick Curry interview with Tom Shippey

Patrick Curry interview with Tom Shippey in November 201