No description available.

This thesis is concerned with so-called higher derivative terms which arise in low energy approximations to certain physical models. In particular, the aim is to investigate the role that such terms play in low energy N=2 supersymmetric gauge theories in 4 dimensions, with gauge group SU(2).Chapter one serves as an introduction to the notions of supersymmetry and superfields. The problem of constructing an effective action which describes the low energy dynamics is introduced, and the construction of the Wilsonian action in terms of light and heavy modes is developed. The concept on a derivative expansion is also described. Chapter two introduces N=2 supersymmetric gauge theories with spontaneous symmetry breaking. It is observed that such systems always have a Bogomolnyi bound, and the consequences are discussed. We then develop a derivative expansion of this system in terms of N=2 superfields, drawing particular attention to the next-to- leading order derivative term (that is, those with 4 derivatives/8 fermions). The duality properties of such a term are reviewed, and their impact on the mass formula discussed. Conclusions are drawn as to their influence on the results of Seiberg and Witten. Chapter three deals with a non-renormalisation theorem for the next-to-leading order higher derivative term proposed by Dine and Seiberg. This states that instanton contributions to such a term in massless N=2 SU(N(_c)) gauge theories vanish when the number of flavours N(_f) = 2N(_c). We prove this result using the ADHM formalism for multi-instantons in the case N(_c) = 2.

Veiksmo pavadinimo konstrukcijos – būdingi šiuolaikinių technologijų, mokslo, teisės verslo ir daugelio kitų sričių kalbos bruožai. Šie žodžiai suteikia pavadinimą įvairiems procesams, procedūroms, metodams ir kt., todėl jie plačiai vartojami įvairiuose oficialiuose dokumentuose, ir būtent šie dokumentai dažnai apibūdinami kaip turintys bene daugiausia veiksmų pavadinimų konstrukcijų. Šiais laikais žmonės, kalbantys skirtingomis kalbomis, nuolat turi bendrauti, ir todėl dažnai atsiranda būtinybė versti oficialius dokumentus iš vienos kalbos į kitą. Taigi, pagrindinė keliama hipotezė, kad vertėjai, versdami oficialius dokumentus, vartoja tam tikrus žodžius, kurie apibrėžia skirtingus veiksmus, ir jie verčia šiuos žodžius pasitelkdami pačias produktyviausias priemones, t.y. produktyviausias priesagas anglų ir lietuvių kalbose, tuo tarpu kitas priesagas vartodami labai retai. Šio magistrinio darbo tema – „Veiksmo pavadinimo konstrukcijos dalykinio stiliaus tekstuose” (lyginamoji analizė). Nors praeityje daugelis mokslininkų tyrinėjo veiksmo pavadinimo konstrukcijas tiek anglų, tiek lietuvių kalboje, šios konstrukcijos dar nebuvo nagrinėjamos oficialiuose dokumentuose bei lyginamos tarpusavyje. Magistrinio darbo tikslas – atskleisti būdus, kaip yra sudaromi veiksmų pavadinimai, ir kaip jie yra verčiami anglų ir lietuvių kalbų dalykinio stiliaus tekstuose, atsižvelgiant tiek į jų formą, tiek į prasmę. Šiame darbe buvo apibrėžta veiksmo sąvoka, išskirta derivacinės morfologijos... [toliau žr. visą tekstą] / Action defining words are characteristic features of the modern language style of technology, science, law, business and many other fields. They create an individual subgroup of naming units in the vocabulary inventory. From the point of view of terminological use, action defining words may designate processes, procedures, methods, ways of processing materials and administration acts. Such words are widely used in different formal documents, and, therefore, the texts are characterized as having a great many of action defining words. Nowadays, as different language speakers regularly communicate, formal documents are facing the necessity to be translated from one language to another. Thus, the main hypothesis of the research is suggested by the fact that in formal texts translators use a determined set of words which define actions and consequently their translations often are performed in a particular manner: they use the most productive English and Lithuanian suffixes leaving aside other linguistic means. In other words, translators do not vary and choose the easiest ways how to express the action in the process of translating. Although there are many research studies carried out on the action defining words by the English and Lithuanian linguists, such as Quirk (1972), Holvoet (2006), Keinys (1999), Pakerys (2006), comparative investigations on the issue of the action defining words in English and Lithuanian are not widespread. This Master thesis aims at revealing the means... [to full text]

No description available.

Flying fruit flies (Drosophila melanogaster) locate a concealed appetitive odour source most accurately in environments containing vertical visual contrasts (Frye et al, 2003). To investigate how visuomotor and olfactory responses interact to cause this phenomenon, I implement a tracking system capable of recording flies’ flight trajectories in three dimensions. I examine free-flight behaviour in three different visual environments, with and without food odour present. While odour localisation is facilitated by a random chequerboard pattern compared to a horizontally striped one, a single vertical landmark also facilitates odour localisation, but only if the odour source is situated close to the landmark. I implement a closed-loop systems-level model of visuomotor control consisting of three parallel subsystems which use wide-field optic flow cues to control flight behaviour. These are: an optomotor response to stabilise the model fly’s yaw orientation; a collision avoidance system to initiate rapid turns (saccades) away from looming obstacles; and a speed regulation system. This model reproduces in simulation many of the behaviours I observe in flies, including distinctive visually mediated ‘rebound’ turns following saccades. Using recordings of real odour plumes, I simulate the presence of an odorant in the arena, and investigate ways in which the olfactory input could modulate visuomotor control. In accordance with the principle of Occam’s razor, I identify the simplest mechanism of crossmodal integration that reproduces the observed pattern of visual effects on the odour localisation behaviour of flies. The resulting model uses the change in odour intensity to regulate the sensitivity of collision avoidance, resulting in visually mediated chemokinesis. Additionally, it is necessary to amplify the optomotor response whenever odour is present, increasing the model fly’s tendency to steer towards features of the visual environment. This could be viewed as a change in behavioural context brought about by the possibility of feeding. A novel heterogeneous visual environment is used to validate the model. While its predictions are largely borne out by experimental data, it fails to account for a pronounced odour-dependent attraction to regions of exclusively vertical contrast. I conclude that visual and olfactory responses of Drosophila are not independent, but that relatively simple interaction between these modalities can account for the observed visual dependence of odour source localisation.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Because games set in persistent virtual game worlds (VGWs) have massive numbers of players, these games need methods of characterisation for playable characters (PCs) that differ from the methods used in traditional narrative media. VGWs have a number of particularly interesting qualities. Firstly, VGWs are places where players interact with and create elements carrying narrative potential. Secondly, players add goals, motives and driving forces to the narrative potential of a VGW, which sometimes originates from the ordinary world. Thirdly, the protagonists of the world are real people, and when acting in the world their characterisation is not carried out by an author, but expressed by players characterising their PCs. How they can express themselves in ways that characterise them depend on what they can do, and how they can do it, and this characterising action potential (CAP) is defined by the game design of particular VGWs. In this thesis, two main questions are explored. Firstly, how can CAP be designed to support players in expressing consistent  characters in VGWs? Secondly, how can VGWs support role-play in their rule-systems? By using iterative design, I explore the design space of CAP by building a semiautonomous agent structure, the Mind Module (MM) and apply it in five experimental prototypes where the design of CAP and other game features is derived from the MM. The term semiautonomy is used because the agent structure is designed to be used by a PC, and is thus partly controlled by the system and partly by the player. The MM models a PC's personality as a collection of traits, maintains dynamic emotional state as a function of interactions with objects in the environment, and summarises a PC's current emotional state in terms of `mood'.   The MM consists of a spreading-activation network of affect nodes that are interconnected by weighted relationships.  There are four types of affect node: personality trait nodes, emotion nodes, mood nodes, and sentiment nodes. The values of the nodes defining the personality traits of characters govern an individual PC's state of mind through these weighted relationships, resulting in values characterising for a PC's personality. The sentiment nodes constitute emotionally valenced connections between entities. For example, a PC can `feel' anger toward another PC. This thesis also describes a guided paper-prototype play-test of  the VGW prototype World of Minds, in which the game mechanics build upon the MM's model of personality and emotion. In a case study of AI-based game design, lessons learned from the test are presented. The participants in the test were able to form and communicate mental models of the MM and game mechanics, validating the design and giving valuable feedback for further development. Despite the constrained scenarios presented to test players, they discovered interesting, alternative strategies, indicating that for game design the `mental physics' of the MM may open up new  possibilities.The results of the play-test influenced the further development of the MM as it was used in the digital VGW prototype the Pataphysic Institute. In the Pataphysic Institute the CAP of PCs is largely governed by their mood. Depending on which mood  PCs are in they can cast different `spells', which affect values such as mental energy, resistance and emotion in their targets. The mood also governs which `affective actions' they can perform toward other PCs and what affective actions they are receptive to. By performing affective actions on each other PCs can affect each others' emotions, which - if they are strong - may result in sentiments toward each other. PCs' personalities govern the individual fluctuations of mood and emotions, and define which types of spell PCs can cast. Formalised social relationships such as friendships affect CAP, giving players more energy, resistance, and other benefits. PCs' states of mind are reflected in the VGW in the form of physical manifestations that emerge if an emotion is very strong. These manifestations are entities which cast different spells on PCs in close proximity, depending on the emotions that the manifestations represent. PCs can also partake in authoring manifestations that become part of the world and the game-play in it. In the Pataphysic Institute potential story structures are governed by the relations the sentiment nodes constitute between entities.Because games set in persistent virtual game worlds (VGWs) have massive numbers of players, these games need methods of characterisation for playable characters (PCs) that differ from the methods used in traditional narrative media. VGWs have a number of particularly interesting qualities. Firstly, VGWs are places where players interact with and create elements carrying narrative potential. Secondly, players add goals, motives and driving forces to the narrative potential of a VGW, which sometimes originates from the ordinary world. Thirdly, the protagonists of the world are real people, and when acting in the world their characterisation is not carried out by an author, but expressed by players characterising their PCs. How they can express themselves in ways that characterise them depend on what they can do, and how they can do it, and this characterising action potential (CAP) is defined by the game design of particular VGWs. In this thesis, two main questions are explored. Firstly, how can CAP be designed to support players in expressing consistent  characters in VGWs? Secondly, how can VGWs support role-play in their rule-systems? By using iterative design, I explore the design space of CAP by building a semiautonomous agent structure, the Mind Module (MM) and apply it in five experimental prototypes where the design of CAP and other game features is derived from the MM. The term \textit{semiautonomy} is used because the agent structure is designed to be used by a PC, and is thus partly controlled by the system and partly by the player. The MM models a PC's personality as a collection of traits, maintains dynamic emotional state as a function of interactions with objects in the environment, and summarises a PC's current emotional state in terms of `mood'.   The MM consists of a spreading-activation network of affect nodes that are interconnected by weighted relationships.  There are four types of affect node: personality trait nodes, emotion nodes, mood nodes, and sentiment nodes. The values of the nodes defining the personality traits of characters govern an individual PC's state of mind through these weighted relationships, resulting in values characterising for a PC's personality. The sentiment nodes constitute emotionally valenced connections between entities. For example, a PC can `feel' anger toward another PC. This thesis also describes a guided paper-prototype play-test of  the VGW prototype World of Minds, in which the game mechanics build upon the MM's model of personality and emotion. In a case study of AI-based game design, lessons learned from the test are presented. The participants in the test were able to form and communicate mental models of the MM and game mechanics, validating the design and giving valuable feedback for further development. Despite the constrained scenarios presented to test players, they discovered interesting, alternative strategies, indicating that for game design the `mental physics' of the MM may open up new  possibilities.The results of the play-test influenced the further development of the MM as it was used in the digital VGW prototype the Pataphysic Institute. In the Pataphysic Institute the CAP of PCs is largely governed by their mood. Depending on which mood  PCs are in they can cast different `spells', which affect values such as mental energy, resistance and emotion in their targets. The mood also governs which `affective actions' they can perform toward other PCs and what affective actions they are receptive to. By performing affective actions on each other PCs can affect each others' emotions, which - if they are strong - may result in sentiments toward each other. PCs' personalities govern the individual fluctuations of mood and emotions, and define which types of spell PCs can cast. Formalised social relationships such as friendships affect CAP, giving players more energy, resistance, and other benefits. PCs' states of mind are reflected in the VGW in the form of physical manifestations that emerge if an emotion is very strong. These manifestations are entities which cast different spells on PCs in close proximity, depending on the emotions that the manifestations represent. PCs can also partake in authoring manifestations that become part of the world and the game-play in it. In the Pataphysic Institute potential story structures are governed by the relations the sentiment nodes constitute between entities.

No description available.

Vaccines famously possess positive externalities that make them susceptible to the collective action dilemma: when I get vaccinated, I protect not only myself, but also those who I might otherwise have infected. Thus, some people will have an incentive to free ride on the immunity of others. In a population of rational agents, the critical level of vaccination uptake required for herd immunity will therefore be difficult to attain in the long run, which poses difficulties for disease eradication. In this doctoral dissertation, I explore different implications of the collective action dilemma of vaccination, and different ways of ameliorating it. First: given that coercion or force could solve the dilemma, and democracies may be less likely to engage in policies that violate the physical integrity of citizens, democracies may also be at a disadvantage compared to non-democracies when securing herd immunity. In essay I, I show that this is, empirically, indeed the case. Barring the use of extensive coercion therefore necessitates other solutions. In essay II, I highlight the exception to individual rationality found in other-regarding motivations such as altruism. Our moral psychology has likely evolved to take other's welfare into account, but the extent of our prosocial motivations vary: a wider form of altruism that encompasses not just family or friends, but strangers, is likely to give way to a more narrow form when humans pair-bond and have children. This dynamic is shown to apply to the sentiments underlying vaccination behavior as well: appeals to the welfare of society of getting vaccinated have positive effects on vaccination propensity, but this effect disappears in people with families and children. On this demographic, appeals to the welfare of close loved ones instead appears to have large effects. In essay III, I investigate whether the prosocial motivations underlying vaccination behavior are liable to be affected by motivation crowding - that is, whether they are crowded out when introducing economic incentives to get vaccinated. I find that on average, economic incentives do not have adverse effects, but for a small minority of highly prosocially motivated people, they might.

Participants executed right-handed reach-to-grasp movements toward horizontally translating targets. Visual feedback of the target when reaching, as well as the presence of additional cues placed close (Experiment 1) or far (Experiment 2) above and below the target’s path was manipulated. Additional cue presence appeared to impair participants’ ability to extrapolate the disappeared target’s motion, and caused grasps for occluded targets to be less accurate. Final gaze and grasp positions were more accurate when reaching for leftward moving targets, suggesting individuals use different grasp strategies when reaching for targets travelling away from the reaching hand. Comparison of average fixations at reach onset and at the time of the grasp suggested that participants accurately extrapolated the occluded target’s motion prior to reach onset, but not after, resulting in inaccurate grasps. New information is provided about the eye-hand strategies used when reaching for moving targets in unpredictable visual conditions. / October 2016