McGill Science Undergraduate Research Journal

Conflicts with de Sitter Vacua in Superstring Theory

Jeffrey Morais — 2025-03-31

Models of our universe lack consistency at different energy scales, so we require a theory with ultraviolet (UV) completion such as string theory. A suitable candidate to model our universe in this framework is de Sitter space, a spacetime which expands and has positive curvature. When describing the expansion of this space, however, one computes the wrong sign for the cosmological constant that would not allow for an expanding universe. This motivates one to consider corrections from a quantum theory to reproduce the correct positive sign for the cosmological constant. The conditions that cause this incorrect sign are known as the \textit{swampland criteria}, and prevent de Sitter space from being realized in a consistent manner at different energy scales. We look at a framework to avoid the swampland restriction in a UV-complete theory by considering de Sitter space resulting from compactifications of type IIB superstring theory. In particular, we demonstrate that the definitions of particles in an expanding UV-incomplete theory leads to inconsistencies in the definition of the de Sitter vacuum states. Furthermore, we review previous attempts to prevent these inconsistencies by constructing coherent states that expand and have the desired de Sitter isometries over supersymmetric Minkowski space. These states add quantum corrections to the metric operator, resulting in the cosmological constant carrying the correct sign. Therefore, the de Sitter space can be used in a UV-complete theory to model our universe.

Neural Complexity and Prognosis: Predicting Recovery in Pediatric Epilepsy Using EEG Markers

Marlo Naish — 2025-03-31

Predicting patient functional outcomes is an indispensable part of clinical care in the Pediatric Intensive Care Unit (PICU), especially for children with epilepsy, a prominent neurological emergency. Electroencephalography (EEG) is a dynamic tool for assessing brain activity, with brain complexity and spectral power features emerging as predictors of consciousness recovery. We investigated whether patients’ EEG activity under anesthesia could predict their recovery, using data from 12 pediatric epilepsy patients (mean age: 11.0±2.2 years). Neural complexity, the intricacy of connectivity between brain regions, is heavily implicated in a patient’s capacity for consciousness. We hypothesize that neural complexity will be a stronger predictor of patient outcomes than spectral power and that higher complexity will be associated with better outcomes. EEG features were analyzed during sedated, baseline (non-sedated), and difference states. Recovery was assessed three months post-injury using the Glasgow Outcome Scale-Extended (GOS-E). The predictive performance of significant EEG markers was evaluated using logistic regression with leave-one-out cross-validation and permutation testing. Baseline EEG features showed minimal prognostic power, whereas sedation and difference states yielded high prognostic accuracy. In the sedated state, the complexity features rate entropy and Lopez-Ruiz-Mancini-Calbet Complexity (HC-LMC) predicted recovery, separating good and poor outcomes with 100% accuracy. These findings demonstrate that EEG markers of complexity can predict the recovery of consciousness in pediatric epilepsy patients under anesthesia. Therefore, EEG analysis could be an accessible, accurate, and powerful prognostic tool in clinical settings. Future research should explore these results in larger samples to validate the findings that rate entropy and HC-LMC are predictive of recovery. Further, these features should be studied in patients of different etiologies to analyze their potential as generalizable markers of consciousness.

Chromosomal Instability and IL6-Mediated Inflammatory Signaling in Human Lymphoma Cells

Veronika Müller — 2025-04-10

Chromosomal Instability (CIN) is a hallmark of cancer that significantly impacts tumor evolution and prognosis in lymphomas. This study investigates the relationship between CIN and inflammatory signaling, particularly the IL6 pathway, in human lymphoma cell lines. Genomic analysis revealed diverse mutational landscapes across cell lines, reflecting varying degrees of genomic instability. qPCR analysis demonstrated consistent upregulation of IL6 expression upon Vincristine treatment across all tested cell lines. IncuCyte analysis of cell viability after treatment with the CIN-inducing agent BAY1217389 revealed dose-dependent effects, with certain levels of CIN potentially enhancing cell growth. These findings suggest that CIN activates IL6-mediated inflammatory signaling in lymphoma cells, contributing to a pro-tumor microenvironment and potentially modulating therapeutic outcomes.

Improved Hardy-Sobolev Inequality under Moment Constraints

Simon Chen — 2025-03-31

This paper is inspired by Aubin's 1979 result, which established that the best constant in the Sobolev inequality on the n-sphere, S^n, can be improved under the condition of vanishing first-order moments. Recent advancements by Hang and Wang (2021) showed that Aubin's improvement can be generalized to arbitrary higher-order moments. We further extend Hang and Wang's results to the Hardy-Sobolev inequality on S^n by deriving an associated concentration-compactness principle and imposing similar moment constraints. Finally, we briefly outline a framework for extending these results to higher-order Sobolev spaces.

Positive Niche Construction: Incorporating Facilitative Microhabitat into Mechanistic Niche Modeling

Brian Schatteman — 2025-04-01

Researchers in the fields of conservation biology and invasion ecology aim to predict the dispersal of species in a reproducible manner, based on quantifiable relationships between target organisms and their environment, through a process known as mechanistic niche modelling. By identifying physiological constraints unique to an organism and calculating its budget of key resources in a given location, sophisticated estimates of potential activity and fecundity can be developed. These spatially-dependent dynamic energy budgets (DEBs) currently ignore the general phenomenon of biological facilitation and, in particular, positive niche construction, wherein a single species improves the suitability of their local habitat for future individuals by modifying their own microclimate. From bed-forming mussels to canopy-forming trees, diverse species can modify their own microclimates by increasing habitat complexity and, in doing so, ameliorate the same physical stressors explicitly considered in mechanistic niche models. To demonstrate the applicability of facilitative habitat in these models, this study selects two habitat-forming organisms and employs DEB-based hindcasting tools to simulate (1) the growth and allocation impacts of temperature regulation in Mytilus edulis (blue mussel) beds and (2) the near-ground micrometeorological impacts of Fagus (beech) tree canopy coverage. A significant reduction in growth and reproductive capacity in blue mussels beyond their optimal temperature and an overall amelioration of temperature and water stress below the beech canopy were observed. Although further research is required to refine the microclimate and micrometeorological impacts assumed for these model organisms, these results suggest that maturing around conspecifics can facilitate persistence in otherwise poor quality habitat. Thus, both species are predicted to have a significant Allee niche, demonstrating the need to incorporate facilitative habitat into mechanistic niche models, especially those used to predict climate change-induced range shifts.

Assessment of Heart Laterality Defects in Zebrafish to Study Variants of Uncertain Significance in Primary Ciliary Dyskinesia

Divya Kakkar — 2025-04-01

Primary ciliary dyskinesia (PCD) is an autosomal recessive orphan disease (OMIM#244400) characterized by motile ciliary dysfunction. These hairlike organelles are responsible for the mucociliary clearance of the lungs, and varying degrees of infections in the upper respiratory tract—including the inner ear, nasal passage, and lungs—are common in affected children present with PCD. Moreover, ciliary function is critical for embryonic development, and defects in cilia can lead to situs anomalies, which are sometimes associated with congenital heart disease. To date, more than 50 genes have been implicated in the etiology of PCD, each affecting different parts of the motile ciliary apparatus. Testing via multi- or single-gene panels is recommended for confirmation of diagnosis, which enables timely treatment initiation and familial risk counselling. Unfortunately, for a significant proportion of children with clinical features consistent with PCD, a molecular diagnosis cannot be established. For many of these children, genetic testing returns a variant of uncertain significance (VUS) in a known PCD gene. Hence, there is a pressing need to develop strategies to validate unresolved PCD variants for their pathogenicity. The overall aim of this project is to resolve VUSs in children with suspected but genetically unconfirmed PCD by use of zebrafish (Danio rerio). As a key PCD gene in humans, DNAAF1 has a dnaaf1 homolog in zebrafish, making this model highly relevant for studying human PCD phenotypes. By employing gene knock-down technology (antisense morpholino oligonucleotides; MO), we established and characterized PCD-specific developmental readouts for the zebrafish gene dnaaf1, which affect different aspects of motile ciliary ultrastructure. We observed an increase in ventral body curvature and hydrocephalus in embryos with dnaaf1-MO, with 38% of dnaaf1-MO knockdown embryos showing heart-laterality defects. These phenotypic outcomes not only provide a concrete framework for assessing PCD-related developmental defects in zebrafish but also offer a platform for validating VUSs in human PCD genes. By performing co-injection experiments with patient-derived VUSs and examining the resulting phenotypic alterations, we can directly link specific genetic variants to observable PCD-like traits, offering a robust methodology for determining the pathogenicity of previously uncharacterized variants. This approach aims to enhance the accuracy of genetic diagnoses in PCD and provide new insights into its molecular mechanisms.

Assessing Changes in Feed Security of the Québec Dairy Industry in 2050

Cassia Attard — 2025-03-31

Understanding the effects of climate change is central to assessing the resilience of the agricultural sector in Québec. The dairy industry is vulnerable as climate change alters yields for cattle feed grown on-farm. Québec dairy farmers have adopted various strategies to mitigate greenhouse gas emissions on farms, incorporating sustainable agricultural practices such as improved waste and manure management, and altering cow diets to reduce enteric (digestive) methane production. The last of these practices --– altering cow diets that reduce enteric methane emissions --– is valuable, yet it introduces a tradeoff between emission reduction and climate adaptation. Indeed, diets that reduce methane emissions may require crops that are less resilient to future climate conditions, whereas climate-resilient feed crops may not offer the same methane-reduction benefits. In 2050, Québec dairy farmers may not be able to grow all feed crops on their land to support herd health and milk output, both metrics of feed security. Accordingly, this study assesses the regional feed security of the Québec dairy industry by modelling the impact of crop yield change in two climate scenarios and with three diet compositions in 2050. Results show that in 2050, methane-reducing corn-heavy diets will require more cropland than hay- or soy-based diets, presenting an environmental tradeoff between land use and methane emissions. The analysis reveals high projected intraprovincial variability in feed security, with Eastern Québec predicted to be more feed secure than Southwestern Québec. The importance of a sustainable and self-sufficient dairy industry is increasingly important in the face of climate change. More broadly, this research aims to identify potential approaches for farmers to support future successful dairy operations.

Asymmetry of Pain-Induced Facial Grimacing

Elodie Nickner — 2025-04-01

Pain has two main components: the sensory-discriminative (the quality, intensity and location of pain) and the motivational-affective (the emotional aversiveness of pain reflective of suffering). A plethora of translational preclinical and clinical measures for the sensory-discriminative component exist (e.g., von Frey, cold pressor). However, few existing measures capture the more elusive motivational-affective component, and those that do are hampered as they are not translatable across species. Post-lesion evaluation of facial grimacing of emotion-related areas of the brain suggests that the Mouse Grimace Scale is reflective of the motivational-affective component. Facial expressions of emotion (e.g., fear, anger) are lateralized such that the left side of the face exhibits facial expressions more strongly than the right side. Comparing pain-induced facial grimacing to facial expressions of emotion is one way to determine which component of the pain experience is most captured by the Mouse Grimace Scale. We hypothesized that grimacing would be lateralized to the left side of the face. Examining lateralization of pain-induced facial grimacing is novel to pain research. We examined the asymmetry of pain-induced facial grimacing in CD-1 mice using inflammatory, neuropathic, and reflexive pain. And we found that pain is expressed predominantly on the right side of the face, contrary to other emotions. Our findings have important implications for the measurement of pain, as characterized by suffering, in non-verbal populations and for application in veterinary care settings.