Species distribution models must balance the need for model generality with that for precision and accuracy. This is critical when modelling range-expanding species such as invasive species. Given the increased use of species distribution models to study invasive species-landscape relationships, a better understanding of the effect of spatial scales, sampling biases, model transferability and discrepancies between different models’ future predictions is necessary. This dissertation addresses these knowledge gaps using mute swans (Cygnus olor) as a case study species. I specifically examine mute swan’s distributions in parts of their native range of Britain and their non-native range of Ontario, Canada. I first investigate which environmental variables at which spatial scales best explain mute swan’s distribution in its non-native range. Second, I perform a sample selection bias study to examine predictive accuracy when species distribution models are built using varying ranges of environmental variables and applied to broader spatial extents. Third, I examine the potential for, and limitations of model transferability between native and non-native regions. Finally, I use two different modelling approaches and three different climate change and land use change scenarios to predict future mute swan habitat suitability. The results indicate that (1) models with better predictive accuracy include environmental variables from multiple ecologically-meaningful scales and measured at spatial extents that include a broad range of environmental variable values; (2) models can exhibit asymmetrical transferability; (3) climate change will facilitate mute swan range expansion in the future more than land use change; and (4) mute swans are often found near urban waterbodies. When modelling invasive species distributions, I suggest that ecologists consider: (I) spatial scale of the underlying landscape processes and species’ use of the landscape; (II) variability and range of each environmental variable used for building models; and (III) stage of establishment of the invasive species.

INTRODUCTION: National obesity rates are leading to higher rates of Type 2 Diabetes, increasing the number of people at risk of invasive infections with Methicillin Resistant Staphylococcus aureus (iMRSA) upon onset of ESRD and hemodialysis. However, an association between adiposity and risk of iMRSA has not been researched. AIM: The purpose of this study is to describe the epidemiological characteristics of an iMRSA cohort in the Atlanta metro area between 2005-2008; to examine BMI-related health outcomes within the cohort; and to compare proportions of BMI categories in this cohort to BRFSS data. METHODS: Surveillance data collected by the CDC EIP program on iMRSA in Atlanta, Georgia was used. BMI was calculated for each eligible case. Statistical analysis was carried out in SPSS. Univariate and multivariate binary logistic regression analysis was performed on select variables. A p-value of < 0.05 and a 95% confidence interval (CI) were used to determine significance. BRFSS BMI data for Georgia was compared to the study population. RESULTS: Overweight and obese cases were more likely to be diagnosed with diabetes by regression analysis. Cases with diabetes were at greater odds of having undergone dialysis within the previous year (univariate OR=2.3, p=0.000; multivariate OR=2.5, p=0.000). The proportion of iMRSA patients with diabetes is much greater (42.8%) than in the general population of the United States (7.8-10.7%). DISCUSSION: The results indicate that there may be a higher risk for iMRSA in overweight and obese individuals, particularly if other adiposity-related health problems are present.

In order to predict future range shifts for invasive species it is important to explore their ability to acclimate to the new environment and understand physiological and reproductive constraints controlling their distribution. My dissertation studied mechanisms by which temperature may affect the distribution of two of the most aggressive plant invaders in North America, Bromus tectorum and Bromus rubens. While Bromus tectorum is dominant in the “cold desert” steppes of the Intermountain region of western North America, B. rubens is one of the severe grass invaders in the “hot deserts” of southwestern North America. I first evaluated whether winter freezing tolerance is the mechanism responsible for the distinct northern range limits of Bromus species. Bromus rubens has a slower rate of freezing acclimation that leads to intolerance of sudden, late-autumn reductions in temperature below -12°C, Bromus tectorum, by contrast, cold hardens rapidly and is not impacted by the sudden severe late-autumn cold. Photosynthetic response to temperature does not explain their current range separation. Bromus species differ little in their photosynthetic temperature responses and the acclimation pattern of photosynthesis. Both species acclimated to a broad range of temperature through the amelioration of Pi regeneration limitation at sub-optimal temperatures and improved carboxylation capacity above the thermal optimum which probably resulted from increased thermostability of Rubisco activase. The effect of elevated temperatures during flowering on the seed yield of Bromus species demonstrates that neither species produces seed at 36°C and above. These thresholds are close to temperatures encountered during flowering in their natural environment. In summary, climatic changes will cause northward range expansion of Bromus species due to less severe autumn and winter, while reproductive failure could cause range contraction at their southern margins.

In cases of temporal lobe epilepsy, seizures are often controlled by anterior temporal lobe resection. However, an assessment of the impact of surgery on language is required. Currently-used assessments are either non-specific within regions or use functional magnetic resonance imaging (fMRI), which can suffer signal distortion in the temporal lobes due to the presence of airways. Magnetoencephalography (MEG) shows a complimentary sensitivity, but has not been used for laterality assessment. We present a method that combines fMRI with MEG for optimized sensitivity. MEG activation maps were generated using a beamformer, showing activity in the anterior temporal lobes and lateral occipital cortex. fMRI showed activation in medial temporal lobe regions, the frontal poles and the hippocampus, an area of clinical concern during surgical planning. The present study introduces a method for integrating MEG and fMRI activation to create high-resolution laterality maps in regions of concern for epilepsy.

Pasaulyje operacijos minimaliai invazine metodika tampa vis labiau populiaresnės. Literatūroje galima rasti argumentų ,,už” ir ,,prieš” šia metodiką.. Minimalios invazijos šalininkai teigia, kad pagrindinis metodikos privalumas — greitesnė pacientų reabilitacija. Oponentų teigimu minimalios invazijos totalinis kelio sąnario endoprotezavimas nėra pranašesnis už įprastinį, netgi mano, jog tai padidina komponentų padėties klaidų tikimybę, bei komplikacijų riziką. 70 kelio sąnario artroze sergančių pacientų buvo įtraukta į atsitiktinių imčių tyrimą. 35 pacientai operuoti minimaliai invazine metodika, 35 įprastine. Mes tyrėme operacijos laiką, kelio sąnario judesius. Po 6 ir 12 savaičių kelio sąnario funkcija buvo vertinta pagal Kelio Sąnario draugijos skalę. Rentgenologiniam ištyrimui priekinę, šoninę kelio bei priekinę visos kojos rentgenogramas. Ligonių pasiskirstymas pagal, lytį amžių, kūno masės indeksą bei kelio sąnario pakitimus statistiškai reikšmingai tarp grupių nesiskyrė. Tyrimo metu nustatėme minimaliai invazinė metodika operuotų pacientų greitesnį kelio judesių atsistatymą, geresnius funkcinius rezultatus po 6 sav., bei ilgesnę operacijos trukmę. Po 12 savaičių skirtumo tarp grupių nenustatėme. Taip pat nenustatėme protezo komponentų padėties skirtumų tarp grupių. / Minimally invasive surgery is getting more interest in literature recently. However the reports regarding the effectiveness of this particular technique are controversial. There are reports in the literature that minimally invasive technique is associated with increased number of technical mistakes. Advantages of this technique are faster rehabilitation. In randomized controlled trial we analyzed 70 knee osteoarthritis patients admitted for elective total knee replacement. All patients were randomized to do surgery using minimally invasive or conventional technique. We analyzed operation time, range of motions 1-6 days after surgery. After 6 and 12 week we evaluated total knee replacement patiens according KSS score. For radiographic examination we performed anterior, lateral and long standing x-rays after the surgery. Preoperative data such as severity of osteoarthirtis, sex, age, and functional score did not differ within the groups. Minimally invasive group was associated with longer operation time, faster recovery of range of motions, better knee function 6 weeks after surgery. 12 week after total knee replacement we did not find any differences between the groups. Component position and leg axis deviation did not differ between the groups.

Defining health and economic burden of Invasive Meningococcal Disease (IMD) in Canada is critical to inform Public Health Policy around immunization programs. A comprehensive literature review was conducted to assess available studies, a lack of comprehensive Canadian data to allow evaluation of total economic burden of IMD was identified in Canada. Thus, this dissertation proposes a prospective cost collection methodology tailored to Canadian data and healthcare utilization (HCU). All patient-related HCU is considered and outlined. HCU is then categorized as direct or indirect and relevant direct and indirect healthcare costs are detailed. Intangible costs are described and methodology for capturing these costs using validated quality of life instruments is proposed. As all published economic evaluations of this disease lack prospective collection of data, this study proposes the use of a patient diary to serve as a memory aid during patient cost-collection interviews.

Awareness of the spread of invasive plant species has grown, but quantitative measures of their impacts are lacking. This study analyses the impact of Himalayan blackberry (Rubus armeniacus) on breeding bird diversity finding a significant difference in bird diversity between “natural” and R. armeniacus-dominated understoreys. More bird species were noted in habitats with greater structural and compositional diversity. Simpson’s richness/evenness index was significantly different between habitat types for Stanley Park and Maplewood Flats (P<0.05) but not Jericho Park (P>0.05), likely due to lower overall bird diversity at Jericho Park and lack of overstorey trees at R. armeniacus thickets. When R. armeniacus is the dominant understorey shrub in a forested setting it has the greatest negative impact on breeding bird diversity.

Freshwater ecosystems face unprecedented levels of human-induced stresses and it is expected that the invasion of non-indigenous species will cause the greatest loss of biodiversity in lakes and rivers worldwide. Bythotrephes longimanus is a predatory invertebrate that invaded North America in the early 1980s, first being detected in the Great Lakes, and then moving to a number of inland lakes in Ontario and the northern United States. Using experimental and survey-based approaches, I tested several hypotheses concerning the effects of Bythotrephes on native zooplankton community structure and function. My results indicate that Bythotrephes reduces total abundance, biomass, and richness of zooplankton, especially cladoceran taxa, throughout the ice-free season. As a result of high predation pressure by the invader, total seasonal and epilimnetic zooplankton production was also substantially reduced in invaded lakes, which may have important consequences for the transfer of energy to fish and other taxa that feed on zooplankton. Interestingly, there was some evidence that zooplankton shifted their reproduction in time and space to avoid Bythotrephes, which may buffer the effects of the invader on food web functioning. Other measures of ecosystem function were relatively unaffected by the invasion of Bythotrephes. In addition, Bythotrephes may interact in unexpected ways with other anthropogenic stressors, and act to slow down the process of recovery by preying on species that maintain community abundance during acidification, but also affecting species attempting to recolonize historically acidified lakes. Although dispersal of zooplankton may maintain some of the ecosystem functions provided by zooplankton communities, loss of biodiversity may be a permanent result of invasion. The effects of the continued spread of invasive species across the landscape may be profound, as the invader Bythotrephes has demonstrably altered zooplankton communities and may reduce the ability of freshwater ecosystems to respond to future environmental change and maintain ecosystem functioning. / Thesis (Ph.D, Biology) -- Queen's University, 2007-07-19 14:56:57.102

Bythotrephes longimanus is an invasive, macroinvertebrate from Eurasia that was introduced into the Great Lakes region in the mid 1980s. Bythotrephes introductions into lake ecosystems have resulted in substantial changes in zooplankton communities, including declines in species richness, abundance, biomass and production. Changes in zooplankton communities may alter the quantity and quality of prey to other predators such as cisco (Coregonus artedii), a pelagic forage fish. Here, I conduct a current day comparison of cisco populations to determine if prey consumption by cisco differs in the presence of Bythotrephes, and whether changes in diet result in energetic consequences (changes in growth and condition) for cisco. Effects of Bythotrephes on native zooplankton communities have resulted in substantial changes in the variety and proportion biomass of zooplankton and macroinvertebrate prey types in cisco stomachs, which have in turn modified growth of cisco. Cisco taken from invaded lakes achieve greater total lengths but changes in condition were not detected. This effect may be driven by improved growth in the second and subsequent growing seasons, suggesting that growth consequences for young fish (that do not feed on Bythotrephes) are different than for older individuals. Length-at-structure age data indicate that by the end of the first growing season (age 1) cisco achieve comparable total body lengths in invaded and reference lakes, suggesting that food consumption by young cisco remains unchanged by Bythotrephes. Alternatively, young cisco forage may be reduced in the presence of Bythotrephes, resulting in decreased survival and similar growth among individuals that survive to age 1. In contrast, despite changes in the zooplankton community; growth of older fish (≥ age 2) was enhanced in lakes that have Bythotrephes. Improved growth among older cisco (≥ age 2) in invaded lakes may be related to the presence of a newly attainable, high energy prey source (Bythotrephes). Alternatively, enhanced growth may be explained by lower competition due to reduced recruitment of young cisco (≤ age 1) in invaded lakes. Increased knowledge regarding the effects of Bythotrephes on growth of cisco is important in furthering our understanding of its impact on lake ecosystems. / Thesis (Master, Biology) -- Queen's University, 2010-04-28 22:46:07.756

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