<p> Traditionally, seasonal forcing has been considered to be the major cause of the influenza seasonality. However, Andreasen [2003] showed that repetitive introductions of new strains can lead to cyclic dynamics. The cyclic dynamic produced by his model is not seasonal, because the length of seasons cannot be defined in his model. In this report, we develop a model that combines a stochastic mutation process with a two-strain competition process governing the spread of the mutant strain. This model can produce stable seasonal dynamics. If we introduce a small seasonal forcing to the transmission rate, the length of a season can be regulated to one year if the unforced system oscillates with a period close to one year. If the system has a period that is far from one year, then the forced system may behave chaotically.</p> / Thesis / Master of Science (MSc)

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Yes / This paper presents a simulation study into the characteristics of a vehicle experiencing steering drift under straight line braking. Simulation modelling has been performed using a multi-body dynamics analysis based on a model of an actual vehicle. Front and rear suspension parameters have been modelled as rigid links joined with flexible bushes so as to assess their effect on a vehicle while braking. Suspension geometry and alignment settings, which define characteristic responses such as lateral acceleration, yaw velocity, toe, and caster angles of a vehicle in a transient manoeuvre, are primary to a vehicle¿s directional stability. Any symmetric inconsistencies in these settings will potentially affect a vehicle¿s performance. The findings from this research have increased the understanding of the causes of steering drift during braking conditions.

Flazasulfuron is one of the newest sulfonylurea (SU) herbicides to be registered for use in the fine turf industry. Flazasulfuron is safe for use on bermudagrass (Cynodon dactylon), and zoysiagrass (Zoysia japonica) yet controls several grass, broadleaf, and sedge weeds. In fine turf, flazasulfuron controls cool-season grasses such as tall fescue (Festuca arundinacea) and perennial ryegrass (Lolium perenne) without harming warm-season grasses. Although SU herbicides like flazasulfuron bring several potential benefits to turfgrass markets, there are also several concerns related to using these herbicides in turfgrass areas. For many plant species, SU herbicides can cause phytotoxicity or death at less than 1 g ai/ha-1indicating small quantities of active ingredient are required to cause problems if herbicide moves in the environment. Herbicide moves to nontarget plants either after it has been applied via lateral relocation or during application via spray drift. Trials were conducted to evaluate flazasulfuron and trifloxysulfuron sodium tracking, runoff and drift in turfgrass environments. Field trials were conducted at six locations across the US to evaluate effects of irrigation, herbicide treatment, nontreated buffer distance, and time of tracking on creeping bentgrass (Agrostis stolonifera) putting green response to dislodged herbicide residues. Although average turf injury did not exceed 2%, significant differences were noted when treated plots were irrigated prior to tracking. In addition, putting green injury was negatively correlated and normalized difference vegetative index was positively correlated with increasing buffer distance. Data indicate the importance of post treatment irrigation to reduce lateral relocation of SU herbicides like flazasulfuron and trifloxysulfuron sodium in turfgrass. In other studies, herbicides were applied to turfgrass on 7 to 11 % slopes and perennial ryegrass injury was assessed at various distances down slope following an irrigation or rainfall event. Herbicide movement in runoff water was indicated by perennial ryegrass discoloration as much as 18 m below treated plots when excessive herbicide rates were applied to saturated soils. Based on perennial ryegrass injury, flazasulfuron at the rates tested was equivalent or more mobile than trifloxysulfuron sodium and equivalent or less mobile than pronamide when subjected to irrigation or rainfall soon after application to saturated soils. To assess spray drift, a bioassay based on corn height reduction was conducted and corn plants were exposed to potential spray drift in field conditions using conventional turfgrass spray equipment. A sprayer was operated when wind speeds were between 6.4 and 9.6 km h-1 and sentry plants were placed various distances between 0 and 30 m down wind. Wind speeds and direction were confirmed with anemometers and neutrally-buoyant balloons. Herbicide drift was not detected beyond 4.6 m downwind of either herbicide application. Data suggest a 5- to 8-m nontreated buffer area should sufficiently protect neighboring cool-season turfgrasses and other plants against flazasulfuron drift, runoff, and tracking as long as product is not applied to saturated soils and irrigated prior to traffic. / Master of Science in Life Sciences

Integrating nanometer-sized pores into low-k ILD films is one of the approaches to lower the RC signal delay and thus help sustain the continued scaling of microelectronic devices. While increasing porosity of porous dielectrics lowers the dielectric constant (k), it also creates many reliability and implementation issues. One of the problems is the little understood metal ion diffusion and drift in porous media. Here, we present a rigorous simulation method of Cu diffusion based on Master equation with elementary jump probabilities within the contiguous dielectric film, along the pore boundary, from the dielectric matrix to the pore boundary, and from the pore boundary to the matrix material. In view of the diffusional jump distance being as large as 2 nm, the nano-pores being on a similar length scale, and the film thickness being only a few tens of nanometers, the conventional diffusion equation in differential equation form is grossly inadequate and elementary jump frequencies are required for a proper description of the Cu diffusion in porous dielectric. The present atomistic approach allows a consistent implementation of Cu ion drift in electric field by lowering and raising of the diffusion barriers along the field direction. This will help understand the behavior of Cu interconnects under thermal or electric stress at an atomistic level. Another approach to lower the increasing RC delays is to bring memory and logic closer by integrating memory in the BEOL. Resistive RAM is one such memory is not transistor based and thus, does not require a silicon substrate. Thus, it offers the possibility of integration directly into the back-end reducing memory to logic distance from 1000s of µm to a 10s of nm. This 3D integration also allows for increased density as well. However, one barrier in the implementation of RRAM in the back end is the use of expensive as well as non-BEOL native material in conventional Cu/TaOx/Pt resistive devices. In this thesis, we present our research about functionality of RRAM with porous low-k dielectrics (which are a candidate for CMOS ILD), and through the similar elementary jump simulations, discuss the impact of porosity in dielectrics on the functionality of RRAM. Lastly, we present a cheaper replacement for Pt as the counter electrode in RRAM and show that it functions as good as Pt. This work addresses following three areas: 1. Modeling of diffusion in porous dielectrics through elementary jump based simulation. The model is based on random walk theory of elementary particle jumps. Initially, qualitative simulations are conducted without actual parameters. It is shown that Cu diffusion in porous dielectrics decreases quasi-linearly with porosity. Furthermore, it is shown that morphology of the pores may have a greater effect on diffusivity compared to porosity. The simulations are then calibrated with parameters, and the result is shown to yield a similar diffusivity times as actual process time. 2. Modeling of Cu ions drift in porous dielectrics under electric stress. First, the model is explained, and then qualitative simulation results are presented for porous dielectrics with varied porosities and morphologies. 3. Research to find a suitable replacement for Pt as the counter electrode in RRAM devices. The research methodology is discussed and a much cheaper Rh is selected as the potential replacement for Pt. Successful functionality of Rh based resistive devices is presented. / Master of Science / As electronic devices are being scaled for integrating more functions and higher computation, the internal delays are increasing, which may become a bottleneck in performance. To resolve this issue of internal delay, new materials are being proposed to replace the conventional materials to make the chip. One promising material like that are the porous dielectrics, to replace the conventional dielectrics used to manufacture electronic chips. The introduction of ‘air pores’ inside the dielectric used in chips may improve the delay, but it leads to several thermal and electrical reliability concerns. In this thesis, we argue that using differential equations to simulate effects on the nano-scale to explore such reliability issues is insufficient, and a simulation method based on individual atom/ion movement should be used to describe it. Here we provide a simulation model to explain the diffusivity of copper under thermal stress, as well as movement of Cu ions during electric stress in porous dielectrics, using our particle movement based simulation model, and prove that it delivers correct results. Secondly, the delay is especially significant for processor to memory communication. Thus, integrating memory close to processor is another method to reduce the delay. Resistive RAM (RRAM) is one such novel RAM technology that can be integrated close to processor. However due to usage of non-native as well as expensive materials, RRAM has not been commercially integrated close to processor. In this thesis, we also present a functioning RRAM using cheaper materials, as well as materials that are native to present electronics.

Safeners protect crops by enhancing their ability to metabolize various compounds, including herbicides. They primarily work by increasing the crop's tolerance to herbicide damage, activating herbicide-metabolizing proteins, and aiding in their detoxification. This study aimed to investigate the chemical effects of safeners in tomato cultivation and focus on injury reduction and tissue protection. The experiment followed a randomized factorial design (5x4) with four replications repeated twice. We evaluated the effects of herbicides (dicamba, 2,4-D, metribuzin, and sulfentrazone at 1/100) and safeners (benoxacor, fenclorim, melatonin, 2,4,6-T, and an untreated control). Safeners were applied to the seeds before sowing, and herbicides were used as a foliar spray 25 days after sowing (DAS). Visual injury was evaluated 7, 14, and 21 days after application (DAA). Biomass measurements were taken 21 DAA. Results showed that preconditioning tomato seeds with 2,4,6-T, melatonin, and fenclorim 7 DAA significantly decreased injury by 25, 25, and 23%, respectively. Moreover, applying melatonin, benoxacor, and 2,4,6-T 21 DAA led to significantly greater dry biomass, which increased by 1.5, 1.42, and 1.44 times, respectively, compared to the control. This research provides valuable insights into the chemical effects of benoxacor, fenclorim, 2,4,6-T, and melatonin safeners in tomato cultivation. The findings demonstrate the potential for preconditional tomato plants with 2,4,6-T, melatonin, and fenclorim to reduce injury while applying melatonin, benoxacor, and 2,4,6-T can increase dry biomass. Understanding plant defense mechanisms and the protective effects of safeners against herbicide damage contributes to developing effective weed management strategies.

Les propriétés hydrauliques d'un till du Nord du Québec en condition saturée et non saturée ont été étudiées en laboratoire à l'aide de l'essai de conductivité hydraulique et l'essai de succion qui permet d'obtenir la courbe de rétention d'eau. Les essais ont été réalisés avec des échantillons compactés sous différentes conditions de teneur en eau et de masse volumique sèche, de manière à évaluer l'influence de ces conditions sur les propriétés hydrauliques. Les études précédentes ont montré qu'une structure agrégée se développe dans le till lorsqu'il est compacté de côté sec de l'optimum Proctor, c'est-à-dire à un degré de saturation de compactage inférieur au degré de saturation optimum (Sr0 < Sr-opt). Le till étudié dans le cadre de cette étude diffère de ceux utilisés dans les études précédentes par son très faible pourcentage de particules argileuses (< 2 μm) de 0,7%. L'objectif principal de cette étude est d'évaluer l'influence des conditions de compactage sur la conductivité hydraulique et la courbe de rétention d'eau et de déterminer si une structure agrégée se développe lorsque le till est compacté du côté sec de l'optimum. Les résultats expérimentaux typiques de la conductivité hydraulique saturée obtenus pour les échantillons compactés du côté humide de l'optimum (Sr0 > Sr-opt) avec un indice des vides de 0,328 varient de 2,6 x 10-7 à 8,6 x 10-7 m/s. Les conductivités hydrauliques typiques obtenues pour les échantillons compactés du côté sec de l'optimum (Sr0 < Sr-opt) avec le même indice des vides étaient très similaires, variant entre 2,4 x 10-7 et 9,1 x 10-7 m/s. Les courbes de rétention d'eau mesurées en laboratoire sont très semblables entre elles, présentant toutes une structure de sol homogène, peu importe si l'échantillon a été compacté du côté sec ou du côté humide. Il apparait que la conductivité hydraulique et la courbe de rétention d'eau de ce till sont très peu influencées par le degré de saturation de compactage. Ceci peut être expliqué par le très faible pourcentage de particules argileuses, qui prévient la formation d'agrégations de particules dans la structure du till lorsqu'il est compacté du côté sec de l'optimum Proctor. Plusieurs modèles d'estimation de la conductivité hydraulique sont utilisés. Cette étude propose trois nouveaux modèles d'estimation de la conductivité hydraulique saturée pour les tills du Nord du Québec. Le premier modèle met en relation la conductivité hydraulique saturée avec le diamètre des grains de la fraction fine (d50 FF) et le deuxième modèle est une équation modifiée de Kozeny-Carman et Hazen basée sur la porosité et une taille de particule effective (d10). Finalement, un modèle permettant d'évaluer l'effet de l'agrégation avec l'équation de Kozeny-Carman modifiée dans les tills compactés est proposé.

Le gisement d'or Amaruq (Nunavut, CA) est situé dans la ceinture de roches vertes néoarchéennes du Groupe de Woodburn Lake. La glaciation Wisconsinienne a entraîné l'érosion du socle, le transport et la formation de dépôts de till masquant le substrat rocheux et les minéralisations associées. Le projet de recherche a pour but de caractériser la signature géochimique et minéralogique du gisement Amaruq dans le till jusqu'à 8,6 km en aval de la minéralisation. Des échantillons de la minéralisation ont été prélevés afin de déterminer la composition chimique des minéraux indicateurs tels que l'or, la scheelite et la tourmaline. Dans le gisement, la tourmaline et la scheelite sont en association paragénétique avec l'or. Le till a été échantillonné le long de 2 transects orientés NNO, parallèles à la direction principale de l'écoulement glaciaire et orthogonaux à la direction du gisement. Les analyses en composantes principales (ACP) de la géochimie du till décrivent la covariance des éléments enrichis dans les roches mafiques à ultramafiques (Fe, Mg, Mn, Ni, Co, Cr) et la minéralisation aurifère (Au, As, Cu, Zn) avec une composante principale 1 (CP1) négative à l'opposé de la variance en éléments enrichis dans les roches felsiques (Si, Al, Na, K, Ba, Be, Hf, Zr, Rb, Sr, U, Th et les éléments des terres rares) avec une CP1 positive. Les échantillons en amont glaciaire ont des scores CP1 uniquement positifs par rapport à des scores CP1 plus hétérogènes en aval. L'analyse discriminante des moindres carrés partiels (PLS-DA) montre que 86 % de l'or et 100 % de la scheelite de la minéralisation d'Amaruq se classifient dans le champ de composition chimique typique des gisements d'or orogénique. Dans le till, 63 % de l'or et 74 % de la scheelite se classifient dans le champ des gisements d'or orogénique. La PLS-DA de l'or du till ne permet pas de distinguer sa provenance entre l'amont et l'aval du gisement. En amont glaciaire, 9 % des grains de scheelite ont une signature chimique similaire à celle du gisement contre 81 % de la scheelite en aval glaciaire. Ces résultats indiquent que la scheelite en amont du gisement est dérivée d'autres sources que la minéralisation d'or orogénique tandis que la scheelite en aval glaciaire provient en majeure partie de la minéralisation affleurante. La faible abondance de tourmaline dans le gisement et le faible nombre de grains de tourmaline identifiés dans les échantillons de till montrent que la tourmaline n'est pas un minéral indicateur pertinent pour cette étude. La caractérisation géochimique et minéralogique du till définit l'origine de la minéralisation érodée et permet son utilisation en prospection glacio-sédimentaire en aval du gisement d'or orogénique Amaruq. / The Amaruq gold deposit (Nunavut, CA) is located in the Neoarchean greenstone belt of the Woodburn Lake Group. The Wisconsinan glaciation caused bedrock erosion, transport and deposition of till masking the bedrock and associated mineralization. The aim of the research project is to characterize the geochemical and mineralogical signature of the Amaruq deposit in till up to 8.6 km down-ice of the mineralization. Core samples from the mineralization were collected to determine the chemical composition of indicator minerals such as gold, scheelite and tourmaline. In the deposit, tourmaline and scheelite are in paragenetic association with gold. Till was sampled along 2 NNW-oriented transects, parallel to the main direction of ice flow and orthogonal to the strike of the deposit. Principal component analysis (PCA) of till geochemistry describes the covariance of enriched elements in mafic to ultramafic rocks (Fe, Mg, Mn, Ni, Co, Cr) and gold mineralization (Au, As, Cu, Zn) with a negative principal component 1 (PC1) as opposed to the variance in enriched elements in felsic rocks (Si, Al, Na, K, Ba, Be, Hf, Zr, Rb, Sr, U, Th and rare earth elements) with a positive PC1. Up-ice samples have positive PC1 scores compared to more heterogeneous PC1 scores for down-ice samples. Partial least squares discriminant analysis (PLS-DA) shows that 86 % of the gold and 100 % of the scheelite from the Amaruq deposit plot in the orogenic gold deposits field whereas in till, 63 % of the gold and 74 % of the scheelite plot in the field for orogenic gold deposits. The PLS-DA of gold in till does not distinguish its provenance between up-ice and down-ice. Up-ice of the mineralization, 9 % of scheelite grains have a chemical signature similar to that of the deposit in contrast to 81 % of down-ice scheelite. The results indicate that scheelite up-ice of the deposit has other sources than orogenic gold mineralization whereas down-ice scheelite was eroded mainly from Amaruq outcropping mineralization. The low abundance of tourmaline in the deposit and the low number of tourmaline grains identified in the till samples shows that tourmaline is not a useful indicator mineral for this study. The geochemical and mineralogical characteristics of till define the origin of the eroded mineralization and can be used for glacio-sedimentary prospecting down-ice from the Amaruq orogenic gold deposit.

La minéralisation aurifère de la propriété Amaruq (Nunavut, CA) est recouverte par divers sédiments glaciaires ayant formé des traînées de débris minéralisés sur des surfaces importantes. Ce projet a pour objectif de caractériser la signature minéralogique et géochimique du gisement aurifère dans le till de surface afin de développer des méthodes de prospection pour les travaux d’exploration. 61 échantillons de till ont été récoltés le long de quatre transects pour déterminer les variations de composition dans la direction principale de l’écoulement glaciaire (NNO). Quatre profils verticaux d’ostioles, un par transect, ont été échantillonnés pour documenter la variation de la signature géochimique avec la profondeur. La signature chimique de la scheelite dans le gisement est comparée à celle retrouvée dans le till et permet de tester son utilisation comme outil de prospection glacio-sédimentaire. Trois des quatre profils d’ostioles présentent des concentrations stables des éléments traces avec la profondeur, indiquant une bonne homogénéisation du till par les processus cryogéniques. Les ostioles sont donc un milieu d’échantillonnage pertinent en région de pergélisol. Les analyses en composantes principales (ACP) de la géochimie des échantillons d’une campagne de till fournie par Mines Agnico Eagle ltée (AEM), et les données des transects, décrivent la variance de la roche encaissante mafique/ultramafique et de la minéralisation aurifére (CP1 et CP2 respectivement). Le krigeage des scores de la CP1 et CP2 indiquent des trains de dispersion vers le NNO, en aval glaciaire des zones minéralisées. Les comptages des minéraux indicateurs (MI : or et scheelite) augmentent de façon importante à environ 1.4 km en aval de la minéralisation dans le secteur est de la propriété, dans un till distal formant des formes drumlinoides. Dans le secteur ouest, recouvert d’un till proximal formant des crêtes morainiques, les comptages des MI et les scores de la CP1 augmentent directement en aval de la minéralisation. Les différences de distance de transport entre ces deux secteurs reflètent un changement de la dynamique glaciaire et démontrent l’importance du contexte local dans les travaux de prospection glaciaire. La comparaison de la signature géochimique de la scheelite entre le gisement et et des échantillons de till du transect de Whale Tail, grâce à des diagrammes discriminants et spectres des terres rares, montrent d’importantes similitudes, démontrant sa potentielle utilisation en prospection glacio-sédimentaire pour des gisements de type orogéniques. / On the Amaruq property (Nunavut, CA), the gold mineralization is covered by a patchwork of glacial sediments, including trains of mineralized debris dispersed over large surfaces. This project aims to define the deposit mineralogical and multi-elemental signatures in surface sediments to guide exploration in the area. A total of 61 samples were collected from frost boils along four NNW transects, parallel to the major ice flow direction, in order to assess the spatial variability of the deposit signature using till matrix geochemistry and indicator minerals. Four profiles in frost boils were sampled, one in each transect, in order to document trace elements depth variation. The scheelite geochemical signature from the deposit is compared to that in till from the Whale Tail transect to test its applicability in drift prospecting. Three out of four frost boil profiles exposed constant trace elements concentrations at depth, reflecting a good till homogenization by cryoturbation. Therefore, frost boils are a suitable medium of sampling for exploration purpose in permafrost terrain. Principal component analysis (PCA) of a previous till survey by Agnico Eagle Mines ldt (AEM) and transect samples define the ultramafic/mafic host rock of the mineralization and a pathfinder element suite characteristic of lode gold deposits (PC1 and PC2, respectively). Kriging of PC1 and PC2 defines a dispersal train oriented NNW, down ice of known mineralization. In the eastern part of the property, covered mostly by a distal till forming drumlinoid ridges, indicator mineral counts (IM: gold and scheelite) increase to a maximum approximately 1.4 km down ice from the outcropping zone. Western transects, largely covered by a proximal till forming morainal ridges, show a sharp increase of counts directly down-ice of mineralization. The difference in glacial transport between these two sectors represents a local change of ice dynamic and shows the importance of understanding the local context in exploration when interpreting glacial dispersal patterns. The comparison of the trace element signature between the deposit and the till scheelite using discriminant diagrams and REE abundance shows similarities, supporting its usefullness in drift prospecting for orogenic gold deposits.