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Long-Term Assessment of Cardiac and Behavioral Phenotypes in Mice with Chronic Heart Failure
Get PDFIntroduction: Heart failure patients have a significant depression risk, with two-to-three-times higher possibility compared to the general population (Rustad et al., 2013). Diminished cerebral oxygen supply from reduced perfusion in heart failure may play a role in the development of mood disorders (Mueller et al., 2020). Suffering from both conditions increases hospitalization and mortality rates compared to patients without depression (Celano & Huffman, 2018). New research is needed for better patient outcomes. Previous murine studies induce cardiac impairments acutely (Frey et al. 2014). However, progressively induced heart failure studies assessing behavior over time are lacking.
Objectives: The aims of this study were: 1) to identify specific timepoints where cardiac phenotypes became more pronounced and, 2) to establish a clear link between the severity of cardiac impairments and the expression of depressive symptoms.
Methods: The plan was to gradually induce heart failure using viral vectors to modify the cardiomyocyte circadian clock through the removal of the clock gene brain and muscle ARNT-Like 1 (Bmal1) (Young et al. 2014). Cardiac and behavioral phenotypes were assessed using heart function and behavior tests.
Results: Immunoblotting analysis revealed no difference in BMAL1 protein levels in control and knockout animals. Consistent with the inability to cause heart failure, cardiac and behavioral phenotypes tested were not significantly different between control and experimental groups over time (p > 0.05).
Conclusion: The heart-brain relationship remains an important research topic. Future experiments should test viral vectors efficiency at larger concentrations and measure differences in BMAL1 protein expression in heart tissue
Trajectory Planning and Control of Cooperative Robotic System for Automated Fiber Placement
Get PDFCooperative robotic system for automated fiber placement (AFP) is a promising solution to fulfill the requirement of manufacturing fiber composites on intricate structures. This project works on the trajectory planning and control of a 13-degree-of-freedom (13-DOF) AFP system. A 1-DOF rotary stage is attached to the end-effector of a 6-Revolute-Spherical-Spherical (6-RSS) parallel robot to hold a Y-shape mandrel, while an AFP head is attached to the end-effector of a 6-DOF serial robot to place fiber with the desired degree. A photogrammetry sensor C-Track 780 can measure the real-time end-effector pose of the robots.
To ensure the desired cooperation performance and limit the communication cost, a distributed control structure with an event-triggered network is developed, based on the measured end-effector pose of the serial robot. An adaptive Kalman filter (AKF) is employed to address uncertain noises in pose estimation. A leader-follower trajectory planning strategy is proposed with the serial robot as the leader and the parallel robot as the follower. A time-jerk optimal trajectory planning scheme is designed for the serial robot considering the kinematic and dynamic constraints. To compensate the serial robot motion and satisfy the AFP geometric constraints, a vision-based trajectory generation approach is developed for the parallel robot.
A position-based visual servoing (PBVS) strategy is proposed for the parallel robot in Cartesian space. To enable the robot to effectively track different trajectories under time-varying conditions, an adaptive sliding mode control method using radial basis function (RBF) neural network is developed to guarantee system robustness and realize the self-tuning of the control gains. In the presence of dynamic uncertainties and external disturbances, a distributed control approach based on adaptive sliding mode controller (ASMC) is developed for the two robots. A deep recurrent neural network (DRNN) is employed to estimate the lumped system uncertainties. The DRNN demonstrates superior learning capability and dynamic adaptability compared to shallow feedforward neural networks. Based on Lyapunov theorem, the stability analyses of the controllers have been done.
The effectiveness and superiority of the proposed algorithms have been validated by simulation and experiment, and comparisons are made with the previous published work
Exploring Granular Scaling Laws via Parabolic Flight Experiments to Advance Lunar Rover Mobility Predictions
Get PDFIt remains a significant challenge to accurately predict the performance of wheels driven on loose granular terrains in low gravity. Planetary rover testing predominantly consists of reduced-weight testing, the use of specially designed soil simulants, or a combination of both; however, these methods overlook how gravity affects the soil during the wheel-soil interaction.
An emerging prediction method is Granular Scaling Laws (GSL), allowing the prediction of wheel mobility metrics (traction, sinkage, and power consumption) across two different gravity levels with sets of nondimensional parameters. However, a recently proposed cohesion term would constrain the wheel radius ratio to the inverse ratio of the gravity levels, indicating that a scaled test wheel on Earth in 1-g should have a radius 1/6 that of a full-scale wheel on the Moon in 1/6-g since Lunar regolith has non-zero cohesion. Furthermore, it is possible for cohesion to become a major component of the soil strength in low gravity. To investigate the cohesion term, this research conducted wheel slip experiments in high fidelity cohesive LMS-1 Lunar regolith simulant during a Lunar gravity parabolic flight campaign in 2023. Comparing the results of this campaign with those from the research group’s earlier 2020 campaign that used noncohesive soil, there is compelling evidence that the cohesion constraint can be ignored for soils with cohesion and bulk density values comparable to real regolith on the Lunar surface. Additionally, refined frictional corrections show that GSL overestimates the traction force, contrary to the result from the previous campaign.
These findings are fundamental to future rover testing and mission planning. Impractical 1/6-scale test units are likely not required for Lunar rovers, and all mobility metrics using GSL should be carefully interpreted despite it being the best physical prediction method currently available
Computational Design of Hammerhead Ribozymes for Logic Computing and Disease Treatment
Get PDFThis thesis explores the intersection of two techniques: evolutionary algorithms (EAs) and allosteric ribozymes (ARs). EAs are population-based search heuristics inspired by natural evolution and ARs are catalytic non-coding RNA (ncRNA) whose activity can be modulated via shape changes induced by external molecules. We present two EAs that design biological devices based on ARs. The first, TruthSeqEr, designs ribogates, logic gates that take short RNA strands as inputs and produce a short RNA output strand as output. Compared to existing approaches, TruthSeqEr is easy-to-use and produces ribogates that are more versatile and that have a greater computational capacity. In silico results show that TruthSeqEr successfully designs ribogates implementing all instances from representative sets of 1, 2, and 3-input functions, including linearly inseparable functions. Motivated by a desire to understand these complex ribogates at an intuitive level, we developed an abstract model that represents each ribogate as a small graph. Analysis of these graphs showed that
ribogates can be classified into families of varying complexity based on shared structural motifs and that ribogates act as a more general version of an artificial neuron. Our second EA, TriCleaver, designs selective ribozymes (sRzs) that cleave the pathogenic mutant mRNA transcript associated with a trinucleotide repeat expansion disorder (TRED) while leaving the functional wild-type (WT) transcript intact. TREDs are debilitating genetic disorders
that result in a severe reduction in quality of life, and in many cases, death. In silico results reveal that compared to existing approaches, TriCleaver is more general, being able to design sRzs that target TREDs in which the mutant is much longer than the WT, as well as TREDs in which the mutant and WT are close in length. In addition, in vitro results in mammalian cells showed that two sRzs designed by TriCleaver selectively silenced the mutant transcript associated with a TRED called OPMD. Altogether, these results highlight the therapeutic promise of combining EAs and ARs
Scream: une autoréflexion des mécanismes d’identifications à travers le slasher postmoderne
Get PDFCette thèse démontre de quelles manières une analyse postmoderne de la quadrilogie cinématographique Scream (Wes Craven, 1996-2011) révèle des mécanismes d’identification plus fluide que celles développées dans les études des slashers modernes. Nous allons démontrer de quelles manières ces mécanismes se voient reconfigurer par une lecture de la série de Wes Craven en tant que pastiche du slasher des années 1970 et 1980. Comment le pastiche, qui est « une forme d’autoréfléxivité moderne employée par de multiples films d’horreur afin de remettre en question les notions formelles dominantes du genre du film d'horreur et leur fondement idéologique » (Benshoff), peut-il ouvrir une nouvelle lecture d’identification performative du genre entretenue dans les études du slasher moderne? En analysant des moments et figures clefs de la franchise, nous affirmons que le public reconnaît les mécanismes d’identification typique du slasher afin de s’y distancer et d'entretenir une projection renouvelée dans le slasher postmoderne. Afin de parvenir à nos fins, nous nous appuyons sur les concepts de pastiche, de parodie, et de performance de genre. Nous étudions également des approches queer au cinéma d’horreur, ainsi que la littérature concernant directement Scream et le slasher. Ces notions seront analysées et mises en discussion, notamment par le biais d’études féministes séminaires comprenant celles de Carol J. Clover, Isabel C. Pinedo, Linda Williams, Sarah Trecansky, et Barbara Creed, parmi plusieurs autres.
This thesis demonstrates the ways in which a postmodern analysis of the Scream cinematic quadrilogy (Wes Craven, 1996-2011) allows for more fluid identification mechanisms than those developed in studies of modern slashers films. We will demonstrate the ways in which these mechanisms are reconfigured by a reading of Wes Craven's series as a pastiche of the 1970s and 1980s slasher film. How can pastiche, which is “a form of modern self-reflexivity employed by multiple horror films to challenge the dominant formal notions of the horror film genre and their ideological underpinning” (Benshoff), can open up a new reading of performative gender identification, supported in studies of the modern slasher? By analyzing key moments and figures within the franchise, we argue that audiences recognize typical slasher identification mechanisms in order to distance themselves from them and maintain a renewed projection of the self into the postmodern slasher. For that purpose, we draw on concepts of pastiche and parody, gender performativity, approaches to queer horror, slasher studies, as well as literature relating directly to Scream. These notions will be analyzed and discussed, notably through the lens of key feminist horror studies, including but not limited to Carol J. Clover, Isabel C. Pinedo, Linda Williams, Sarah Trencansky, and Barbara Creed
MRI-Based Brain Age Estimation Using Supervised Contrastive Learning
Get PDFBrain age estimation models aim to accurately assess a subject's biological brain age based on neuroanatomical features. Various factors, including neurodegenerative diseases, can cause accelerated brain aging and measuring this phenomena could serve as a biomarker for clinical applications. While promising results have been achieved in previous works, there is no consensus on an optimal model for accurate prediction or clinical utility. This thesis proposes using supervised contrastive learning with Rank-N-Contrast (RNC) loss and Grad-RAM for explainability utilizing structural T1w MRI data. Results indicate that the supervised contrastive strategy significantly outperformed ResNet models, achieving a mean absolute error of 4.28 years and an R² of 0.93 with a limited dataset of aging subjects. Benchmark comparisons with state-of-the-art models demonstrated that the supervised contrastive approach achieved comparable performance in our test sample, particularly among older age groups. The Grad-RAM analysis revealed anatomically relevant regions associated with aging, with the more nuanced capabilities exhibited by the supervised contrastive learning approach. Analyses of disease populations revealed significantly higher brain age gaps in Alzheimer's Disease (AD) patients, correlating strongly with ADAS-cog scores (r = 0.37, p = 0.0098), suggesting its potential as a biomarker for assessing AD severity. However, no significant correlation was found between brain age gap and UPDRSIII scores in Parkinson's disease (PD) patients. The Grad-RAM focuses on regions known to be linked to AD and PD, but with little difference to the healthy population. Our study demonstrates the potential of supervised contrastive learning with an RNC loss in brain age prediction, highlighting its ability to outperform other models in smaller datasets
L’image au service de la traduction : une analyse multimodale de Tintin en créole mauricien selon une approche sociosémiotique
Get PDFUn coup d’œil sur la bande dessinée nous montre que ce genre littéraire peut non seulement servir d’outil de réflexion sur la traduction d’éléments visuels, mais, grâce à son langage imagé, il offre également une visibilité à des langues en quête de reconnaissance telles que le créole mauricien (le mauricien). Dans cette analyse de la traduction de Tintin, plus précisément l’album Le Secret de La Licorne, nous souhaitons mettre de l’avant une approche plutôt récente en traductologie, la multimodalité, qui permet d’étudier à la loupe la combinaison entre différents modes de communication, que ce soit la langue verbale, des éléments visuels ou d’autres modes qui ont pour but de communiquer un sens. Comme le but ultime de ce mémoire est de démontrer l’autonomie d’une langue telle que le mauricien, il est nécessaire d’intégrer dans cette analyse multimodale une autre approche qui permet de contextualiser ces modes lors du processus de traduction. La sociosémiotique est une approche qui combine le sens et le social, ce qui fait d’elle un outil efficace pour analyser ces modes lorsqu’ils sont transférés dans un nouveau contexte, et ainsi déterminer ce que leur transfert implique pour la traduction elle-même, mais aussi pour le créole mauricien. Finalement, ce que ce mémoire souhaite également montrer, c’est l’importance de prendre considération le non-dit, l’espace entre les mots, pour que rien n’échappe à l’entendement
Ghost in the Cell: Phonological Primes as Neural Symbols
Get PDFThis dissertation investigates the role of abstractions in linguistic knowledge, particularly focusing on phonological representations and its interface with phonetics. It explores how abstract phonological grammar, which determines the "sound patterns" of languages, impacts speech detection, processing, and production. The work consists of a collection of independent articles, with some written specifically for this dissertation, centered on understanding the phonology-phonetics interface from a substance-free perspective.
Chapter 1 sets the historical context for substance-free phonology, tracing its development from the cognitive revolution of the 1950s and the influence of Noam Chomsky's work, culminating in the biolinguistic program.
Chapter 2 reviews the foundations of substance-free phonology, arguing that its philosophical basis stems from the strong-minimalist thesis and emphasizes reducing phonological content in Universal Grammar (UG). It lays the groundwork for constructing a model of the phonology-phonetics interface, emphasizing a partially veridical relationship between phonological form and phonetic substance.
Chapter 3 examines the implications of a substance-free approach for the phonology-phonetics interface, discussing the challenges of a deterministic relationship between phonological form and phonetic realization. It proposes a hybrid framework that avoids both absolute determinism and complete arbitrariness, supported by neurobiological models of speech processing.
Chapter 4 presents an empirical study using dichotic listening to investigate how bilinguals manage phonological features in speech perception. The study finds that perceptual intrusions from an unattended language are influenced by voicing, supporting a feature specification approach based on privative features and underspecification.
Chapter 5 continues the behavioral investigation with experiments on velar palatalization in Malayalam. It reports significant vowel and suffix effects on palatalization, contributing to understanding the phonological and phonetic division of labor. An interface account, couched in the hybrid framework developed in Chapter 3, is provided.
Chapter 6 discusses neurobiological research on phonological representations, including a project examining event-related potentials (ERP) to differentiate phonological from other linguistic alternations. It also proposes future research on contrasting phonological and phonetic alternations in Hindi and French.
Chapter 7 concludes by reflecting on the dissertation's contributions, emphasizing the unifying theme of abstract substance-free neural symbols in phonological representations, and addressing feedback received throughout the research
Flexural and Shear Behaviour of Fibre-Reinforced Concrete Beams Reinforced with GFRP Bars
No full textDue to the lower elastic modulus and higher tensile strength of glass fibre-reinforced polymer (GFRP) bars compared to steel, the design of GFRP-reinforced concrete (RC) flexural members is governed by serviceability limit states, including deflection and crack width. This study enhances understanding of the flexural and shear behaviour of concrete beams reinforced with GFRP bars through experimental and analytical work. The main objective is to elucidate the effect of GFRP bars and fibre reinforced concrete (FRC) on the flexural and shear response of concrete beams. This investigation evaluates existing design equations in North American standards, offering design recommendations for GFRP-FRC beams.
Accordingly, this research is divided into two main phases. Phase I, “Flexural and Serviceability Behaviour of GFRP-FRC Beams”, examines the impact of macro-synthetic fibres on the behaviour of 11 GFRP-RC beams. The study investigates the deflection equations outlined in the CSA S806-12 and ACI 440.11-22 standards, alongside assessing flexural capacity in accordance with ACI 544.4R-18. Furthermore, digital image correlation (DIC) was utilized to capture the crack propagation, crack width, and deflection up to failure, demonstrating its effectiveness over conventional contact instrumentations such as linear variable differential transducers (LVDTs) and potentiometers.
Phase II, titled “Shear Behaviour of GFRP-RC Beams”, utilizing 15 specimens, explores parameters including reinforcement ratio, stirrup type, stirrup reinforcement ratio, shear span to depth ratio, and fibre content. The study aims to establish the influence of these parameters on shear capacity, failure mode, and strain variation of stirrup and longitudinal rebar. The results indicated that ACI 440.11-22 and CSA S806-12 strain limits for GFRP stirrups are conservative, and a modified equation is proposed. Current GFRP design codes do not consider the effect of fibres on the shear capacity of GFRP-RC beams. Moreover, the design standard ACI 544.4R-18 for fibre-reinforced concrete, developed for members with steel reinforcement, tends to overestimate the shear capacity of FRP-FRC beams. An experimental database was utilized to assess the accuracy of GFRP design code provisions in determining the shear capacity of GFRP-RC beams. A modified equation is proposed to incorporate the effect of macro-synthetic fibres, validated through literature and current tested specimens
The Effects of Economic Conditions on Adolescents’ Mental Health; Evidence from Canada
Get PDFThe relationship between socioeconomic factors and mental health has garnered significant attention, revealing complex connections between economic conditions and psychological well-being. This paper studies the impact of family economic conditions on the mental health of Canadian adolescents using data from the 2017-2018 wave of the Canadian Community Health Survey. To analyze this relationship, a latent variable indicative of economic conditions is created from several indicators of households’ living standard. This latent variable, along with demographic and behavioral factors, is used in an ordinal logistic regression model to evaluate its effect on mental health outcomes. The findings highlight that older adolescents and females experience notably worse mental health. Behaviors such as smoking and alcohol consumption, negatively impact mental well-being, while physical activity is positively associated. Although economic factors significantly influence mental health, they are not the primary determinants of mental well-being among Canadian adolescents