Imagine if you suddenly felt your heart “jumping out of your chest” – this is the case for an estimated 1 in 4 Canadians who experience this rapid and chaotic heartbeat characteristic of atrial brillation (AF).

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The healthy heart works continuously to beat regularly under the control of electrical impulses originating from the sinoatrial (SA) node, the heart’s natural pacemaker. In AF, electrical impulses do not originate in the SA node, but rather, from a different part of the atrium or in nearby pulmonary veins. These abnormal electrical signals become rapid and disorganized, radiating throughout the atrial walls in an uncoordinated manner. This can cause the walls of the atrium to quiver, or brillate, which results in irregular electrical transmission from the atria to the ventricles. A normal heart rate at rest should be between 60-100 beats per minute at rest, but in AF, it can be considerably higher than 140 beats per minute1.

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Affecting more than 33 million individuals worldwide, AF is the most common sustained irregular heart rhythm encountered in clinical practice2. The progression and maintenance of AF results in adverse events, including an increase
in hospitalizations and a ve-fold increase in the risk of stroke3. Given this evidence and anticipated increases in life expectancy within the next several decades, there are clear public health implications for the aging Canadian population.

The Whole Genome Sequencing Project initiated by The Hospital for Sick Children of Toronto intents to enroll patients between one to eighteen years of age with congenital heart disease to test the efficiency of such a method for potential personalized diagnoses and treatments. Twenty-five randomly approached patients were chosen to be observed of their consent rate to the project based on factors of age, gender, ethnicity, presence of heart diseases in the patient’s family, and type of congenital heart disease represented. Females and ethnicities not of European descent are considered to be a part of the minority groups, generally being under represented thus having a lower consent rate. There were no significant correlations between consent rates and familial history of heart disease, type of heart disease and age groups. All these findings can aid in future studies of the SickKids Hospital; which patients should be approached for higher consent rates, and the inclusivity of minority groups to alleviate bias in medical studies.

The invasive European Common Reed (Phragmites australis), first established in North America in the early 1900’s, is now a dominant emergent aquatic plant in many coastal and inland wetlands. A review of the literature was conducted to evaluate the extent of ecological impacts on fishes and their habitat, such as changes in the composition and abundance of native fishes and wetland plants, and alterations to water availability and substrate. The review indicated that a reduction in the abundance of native fishes was common (54.54% of studies), as were impacts to fish habitat (e.g., 54.54% of studies documented a change in wetland plant composition). Many studies were conducted in the eastern and northern United States, which showed that the abundance of juvenile and larval fishes was significantly lower in marshes dominated by P. australis, relative to those dominated by native plant species (Spartina alterniflora); however, changes to wetland plant abundance and composition, water availability, water temperature, nutrient cycling, substrate, reproduction and spawning, genetics of native fishes, and general food web effects were also observed. These results indicate that P. australis poses numerous ecological impacts to the structure and function of wetland habitats, with implications for the ongoing productivity of aquatic ecosystems. 

Alzheimer’s disease (AD) is a neurodegenerative disease. It is a growing concern, demanding the attention of families, scientists, and pharmaceutical companies due to its devastating impacts on patients. The disease is believed to be triggered by pathogenic amyloid beta protein (Aβ) formations in the brain. In order to understand the protein production and the plaque formation in the AD brain, we specifically focused on the ‘Amyloid Cascade Hypothesis,’ which explains the biological pathways and the players in the disease. Focusing on the macro-side, we modelled the progression of AD from neurodevelopment (healthy brain) to neurodegeneration (the disease state) by using the agent based computer simulation program called COBWEB. Our model begins with healthy, developing neurons thriving in the hippocampus and cerebrospinal fluid (CSF) working efficiently. The brain ages throughout the adulthood phase. The onset of the disease and its progression is modelled with plaque formation, a decline in neuron counts, and an inefficient cleaning mechanism close to the end of the experiment. We conclude that our model fulfills its purpose: to provide a visual contrast between health and disease through the slow progression of AD in real time, increasing one’s understanding of this illness. Its accuracy is attributed to Aβ plaque formation, neuronal death, and CSF deterioration. Future projects include testing, designing, and refining new treatments using this model, diminishing the barrier to entry for new ideas, and providing a new tool for teaching AD.

A Q&A with Dr. Brad Bass in Science from the Source.

This project simulates the Concentric Zone model (Ernest Burgess, 1925) using the agent-based simulation software COBWEB, which allows comparison of transportation costs in determining the distribution of agents after a set period of time. The energy an individual uses to move one grid cell is the parameter factor used to represent transportation costs. It was hypothesized that setting up this experiment to recreate a concentric zone environment will develop a stable environment with individual agents staying in their respective zones as determined by transportation costs. However, over a period of time, the agent population would diminish or the zones won’t be as clearly expressed.

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In the control experiment, each agent type stayed in their respective zones and the agent count remained consistent throughout the simulation. Two more experiments were performed to observe their respective effects on the model. By increasing the number of agents, this experiment had similar averages compared the control experiment, indicating that there is a carrying capacity in order to maximize the agent’s survival. By changing AI strategies, one of the agents completely died out, suggesting that the agent’s specific AI strategy for its movement and consumption is important to consider when performing experiments.

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Modelling the distribution of the agents and observing the key factors affecting this distribution is useful for urban planning and transportation management. Additional research to introduce parameters for housing costs is worth exploring in future research activities to provide more interesting and detailed results from the simulation.

Daily commuters of public transportation and private vehicles are exposed to a wide range of traffic-related air pollution (TRAP). However, evidence of differences between commuting method has been building. In this study, the personal ultrafine particle (UFP) and black carbon (BC) air pollution exposures of a high school student were measured during their daily commute. In total, 39 commutes made between the student’s home and school were measured. These commutes were either by bus or private vehicle. Data was analysed using box plots and T-tests of statistical significance. Levels of BC were not significantly higher on buses (mean(SD) = 849(645) ng/m3) than cars (650(689) ng/m3) (p-value = 0.199). For UFP, levels were significantly higher for bus commutes (9393(6923) pts/cm3) than those of private vehicle (4234(6446) pts/cm3) (p-value = 0.045). Our findings suggest that bus commuters may experience higher exposure to UFP relative to private vehicle commuters. The higher UFP exposure may be accounted by the fact that city buses can have a higher air exchange rate due to the constant opening of doors.  As well, buses are mainly diesel vehicles, which are a strong source of UFP.  

Recent advances in computer technology have brought a revolution in ecological modelling. Ecoinformatics and computational ecology make use of various programs, including agent-based modeling algorithms, to study ecological systems. In this study, an in-silico analysis was performed using an agent based modelling software, to analyze the impacts of a potential toxin on Lake Ontario ecosystem. For easier duplication of the real world into the virtual system, the ecosystem was divided into 6 compartments. These compartments include phytoplankton, zooplankton, macroinvertebrates, forage fish, piscivores, and sea lamprey. The test model was performed under five different concentrations of toxin. Each test was repeated 15 times to reduce demographic stochasticity. The results suggest that toxic contaminations, such as mercury, could potentially lead to population reduction in forage fish, piscivores and sea lamprey compartments.