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Essays in Environmental Economics
No full textThis dissertation examines how environmental externalities shape financial markets, regulatory policies, and public well-being, using a combination of empirical analysis and theoretical modeling. The first chapter investigates whether environmental concerns help explain Bitcoin's returns and volatility. Using innovative textual data from Tweets and Google Trends, I construct three proxies for climate risk, each capturing a distinct dimension: aversion, uncertainty, and attention. The findings reveal that climate risk uncertainty (aversion) improves the in-sample predictability of returns (volatility), while climate risk attention enhances the out-of-sample predictive ability of volatility. The second chapter develops a partial equilibrium model to determine optimal emission taxes in the presence of two-sided environmental externalities, two-sided abatement, and one-sided market power. In this case, the taxes imposed on polluting producers and consumers fall below their Pigouvian levels without achieving the first-best. However, if only one side abates, the first-best is achieved by taxing the (un)abating polluters at (below) their respective Pigouvian level. The third chapter employs a difference-in-differences approach to assess the causal effects of prenatal fluoride exposure on birth outcomes in the United States. Results show a significant reduction in birth weight and an increased risk of central nervous system anomalies, especially during the first trimester and among White, married, and more educated mothers, which highlights socioeconomic disparities in vulnerability. Additionally, the effects vary by exposure type, with distinct impacts observed for low-dose cumulative versus high-dose acute exposure
Coherent Radar Backscatter Modelling for Drones in the OFDM Framework
No full textThe problem statement of this thesis is to construct a simple, versatile, closed-form simulation model which can be used to model Orthogonal Frequency Division Multiplexing (OFDM) pulsed-radar reflections from drones.
General simulation methodologies exist which allow a simulation designer to provide an arbitrary transmit waveform, system parameters and a set of point-scatterer positions and velocities representing complex radar targets for each time sample considered in the simulation and to generate signal reflection predictions. On the other hand, certain over-simplified methodologies exist to generate reflection predictions from propellers or drones and significantly simplified to allow a closed-form solution.
The manner in which to simulate signal reflections from complex targets explored in this thesis provides a middle-ground between the over-generalized and over-simplified simulation methodologies and is adapted to the specific use-case of OFDM pulsed-radar to model drone targets. The benefit of this simulation methodology is its ease-of-use and flexibility. The solution allows one to provide system parameters, drone parameters and a drone trajectory to produce accurate backscatter predictions without having to model all the individual point-scatterers for the radar target at each point in time. Additionally, the simulation methodology presented in this thesis is derived in a separate manner than the current standard for complex target modeling which is having well-placed point-scatterers anchored to the simulated target. If one generates prediction results from two separate simulation algorithms, then their certainty in simulation accuracy increases.
This thesis presents how the simulation model derived within produces almost identical results to the state-of-the-art simulation methodology, where the same complex radar target is modeled as a set of moving point-scatters with varying Radar Cross-Sections (RCS) at each point in discrete-time. Since the model derived within require significantly less setup and modeling efforts from the user and provides roughly the same computational complexity for modeling drone targets in the OFDM pulsed-radar framework, it is the better option.
The main metrics used for comparison between the different simulation methodologies are the Fourier transforms of the received signal, micro-Doppler signatures and the range-speed response for the radar system. All three metrics are shown to match the state-of-the-art in the proposed simulation method
Plasmonic Gratings in Optoelectronics and Fluorescence Enhancement
No full textThis thesis is an article-based report on the investigation and innovations which highlight the importance of plasmonic gratings in new device physics studies, fluorescence enhancement, and novel telecommunication chips.
Plasmonic gratings are nanostructures created by periodically patterning a metal film with nanogrooves. These structures are capable of efficiently compensating the momentum mismatch between incident optical illumination and surface plasmon polariton (SPP) modes propagating along the metal film. Whilst a SPP mode is present on the film, one can benefit from their numerous advantageous features such as strong field enhancement in sub-diffraction-limit dimensions, and energetic hot carrier generation on the metal, to design new devices or study device physics. Plasmonic gratings can also perform as efficient structures in coupling the SPP modes on the surface to radiation channels.
A metal-oxide-semiconductor (MOS) based high speed electro optic modulator is reported encompassing a plasmonic grating on the metal layer. The incident optical beam excites SPP mode on the MOS structure via plasmonic grating. Applying the electrical data as a drive voltage to the MOS structure, modifies the effective refractive index of SPP mode through carrier refraction effect in semiconductor layer (Silicon), thereby, modulating the coupling efficiency of incident beam to SPP mode. This provides an intensity modulated beam at the reflection. Numerical analysis, and experimental passive and active characterization of the device is reported. The 5 µm modulator works up to 22 GHz with 4 dB insertion loss and modulation depth of 2% over an optical bandwidth of 100 nm. The modulator offers an innovative solution for non-contact wafer-level testing - a critical and costly step in wafer manufacturing that presents challenges and creates a bottleneck in the transition to smaller technology nodes.
The tunneling current in a similar MOS structure is measured and investigated theoretically. Studying the band diagram of the MOS device under accumulation and inversion regimes, shows that only Fowler-Nordheim tunneling is possible for the carriers transferring through the 5 nm thick Hafnium-dioxide (HfO₂) layer of the MOS structure. Theoretical modeling of the measured tunneling current shows a modified Fowler-Nordheim tunneling (MFN) law rules the dark current and photocurrent under inversion regime, fitting perfectly to the experimental results, and providing an opportunity to extract information such as the type and effective mass of the tunneling species, tunneling barrier height, and available population of carriers to initiate each tunneling process. A new tunneling channel of energetic holes created by SPPs on the metal surface is shown to be initiated from metal towards the semiconductor upon device illumination with an optical beam.
Plasmonic silver gratings had been previously shown to create fluorescing carbon emitters from fabrication residues. In this thesis, the role of SPPs on a plasmonic grating to excite fluorophores strongly and enhance the fluorescence intensity by creating fast and competitive radiation channels, is investigated experimentally. SPPs propagating on the plasmonic grating can couple to the grating diffraction orders, resulting in highly directive radiation which is studied via numerical simulations. Available SPP modes near fluorophores, also reduce the emitters' lifetime through the Purcell factor. This phenomenon is theoretically modelled and emitters' lifetime on the plasmonic grating is measured experimentally.
New fluorescence lifetime measurement method and plasmonic nanoantenna design for controlled localisation of fluorescence enhancement on a periodic structure surface is suggested as possible future research paths
Citizen Support for Democracy and Undemocratic Practices
No full textThis dissertation examines the puzzle of citizen support for undemocratic practices through three lenses, each explored in a distinct research article. These articles consider, respectively, the roles of partisanship, democratic trade-offs, and age in explaining support for undemocratic practices.
The first article begins with an empirical assessment of the subversion dilemma framework across three moderately polarized and multiparty systems. According to this perspective, individual support for undemocratic practices stems, at least partly, from increasingly negative perceptions of opposing partisans' commitment to democracy. The underlying mechanism argues that, in light of these misperceptions, the rational response is to turn to undemocratic practices to remain electorally and ideologically competitive. Using an expanded conceptualization of undemocratic practices, this first study tests the framework in Australia, Canada, and the United Kingdom. The results indicate that misperceptions of out-partisans' commitment to democracy do not substantively explain citizen support for democratic subversion in these three contexts. The results are found to be inconsistent across different types of undemocratic practices, raising questions about the generalizability of existing research between contexts and over an expanded understanding of the concept of undemocratic practices.
In the second article, I investigate the extent to which citizens are willing to trade different dimensions of democracy for better physical and material security. While existing studies on popular support for democratic backsliding have extensively focused on candidate choice experiments, these do not capture the extent to which individuals intrinsically value undemocratic alternatives. In the few studies that look beyond candidates and focus on support for undemocratic practices, results indicate a substantial willingness among citizens to disregard democracy for better economic and physical conditions. Building on these findings, I test the willingness to trade five different dimensions of democracy for better physical and material security (i.e., stronger economy and lower crime rates). The objective is to understand whether citizens' preferences for different dimensions/institutions of democracy shape their willingness to engage in democratic trade-offs. Using a pre-registered conjoint experiment in Australia, Canada, and the United Kingdom, I demonstrate that citizens are less willing to compromise on elections and political rights, but more open to forgo accountability mechanisms. These findings make a substantial contribution to the literature on citizen support for democratic backsliding by identifying which dimensions of democracy people are least (and most) likely to abandon.
In the third and final article of this dissertation, I shift my focus to a demographic variable: age. More specifically, this research is interested in understanding whether and to what extent younger citizens' disconnect with democracy is fueling a shift towards undemocratic practices. I rely on a multi-method approach to examine differences in democratic attitudes across age groups. Using observational and experimental data, I provide robust cross-national evidence that younger citizens' support for democracy is substantially lower than older citizens. Building on these findings, I further demonstrate that youth are far more tolerant of a wide range of undemocratic practices and democratic norm violations. Lastly, I present the results of a conjoint experiment which confirms that younger citizens have significantly lower preferences for democratic societal attributes when compared to their older counterparts. Substantively, these findings contribute to a growing literature on the vulnerability of consolidated democracies to younger peoples' shifting attitudes towards democratic institutions and norms
The Role of Solubility in the Toxicity of Metal Oxide Nanoparticles
No full textMetal oxide nanoparticles (MONPs) represent one of the largest classes of engineered nanomaterials (ENM) in the world. As with ENM in general, MONPs present a challenge for regulatory risk assessment due to the numerous physicochemical properties impacting their toxicity. One of the most critical properties of MONPs is their solubility in biological microenvironments, affected by factors such as their surface area, surface reactivity, and chemical composition. The relative contribution of the particulate and dissolved fractions to toxicity induced by MONPs remains poorly understood. In this context, the underlying question this thesis sought to address was: what is the relative contribution of particulate and dissolved fractions to MONP induced toxicity? To address the question, this thesis employed 21st century toxicological tools in an in vitro lung epithelial model system (FE1) examining MONPs with varying solubility (including ZnO, CuO, NiO, Al2O3, TiO2). In the first approach, FE1 cells were exposed to MONPs, their microparticle analogues, and dissolved metal salts for 2 – 48 h for transcriptomic characterization. In the second approach, the genotoxic potential of the same MONPs and equivalents was assessed using two high-throughput screening assays (CometChip® and Microflow®). Finally, fluorescence darkfield hyperspectral imaging was used to determine the co-localization of a set of MONPs with lysosomes, while the impact of lysosomal dissolution / interaction on MONP toxicity was assessed by measuring changes in viability with and without co-exposure to a lysosomal acidification inhibitor. The results of the transcriptomic characterization and genotoxicity screening indicated compound-specific effects of solubility and the particulate and dissolved species on MONP toxicity; with the ‘HIF1α Signaling’ pathway being identified as a putative biomarker of response to acutely toxic MONPs. Based on microscopy analysis, all MONPs localized to lysosomes, with TiO2 MONPs showing the greatest co-localization. Out of the MONPs tested, lysosomal dissolution only contributed to the toxicity of CuO MONPs. In conclusion, adverse effects of MONPs are not captured solely by their solubility properties, raising concern that existing hazard groupings are based on oversimplifie
La démocratie écosophique : Félix Guattari militant 1985-1992
No full textCette thèse examine la pensée de Félix Guattari à partir de l'idée d'une démocratie écosophique proposée à la fin de sa vie tout en portant une attention particulière à son engagement dans la mouvance écologiste. Il s'agit ainsi de présenter la démocratie écosophique en articulant plusieurs des concepts caractéristiques de la pensée guattarienne, ceux-ci ayant été préalablement l'objet d'une explication détaillée dans un chapitre. De surcroit, la plupart de celles-ci sont appuyées par des exemples concrets tirés des engagements de Guattari dans différents mouvements alternatifs.
Il est d'abord question de la transversalité qui est directement liée à sa critique du centralisme démocratique et à sa recherche de nouveaux modes d'organisation politique. Cette approche vise à créer des groupes-sujets capables de prendre en charge leurs propres déterminations et implique une ouverture à l'altérité favorisant une reconnaissance de la finitude. Ensuite la révolution moléculaire est mise en relation avec les transformations matérielles des moyens de production instigués par les TIC qui bousculent les repères traditionnels et stimule l'émergence de subjectivités mutantes. Il est alors question d'une nouvelle subjectivité militante et des engagements du CINEL. L'idée d'une ère dissensuelle postmédiatique insiste sur la nécessité de réinventer les moyens de concertation et permet de présenter sa critique de l'infantilisation mass-médiatique et sa conceptualisation d'une utilisation postmédiatique adaptée aux groupes-sujets ouvrant la perspective d'une ère de l'autoréférence. Cela est illustré par ses engagements dans les radios libres et la télématique avec le service 3615 ALTER du réseau Minitel. Le traitement détaillé de l’aspect dissensuel montre entre autres que l’amour de la différence est vecteur d’une créativité pouvant mener à l’invention d’une démocratie à la hauteur du pluralisme. Ici ce sont les exemples du mouvement-parti-réseau Arc-en-ciel et de la multiappartenance aux partis Les Verts et Génération écologie qui sont mobilisés. La présentation du nouveau paradigme esthétique examine comment la créativité intervient au niveau des processus de subjectivation et ainsi comment sortir de l’homogenèse favorisée par le CMI et engager des hétérogenèses. C’est alors l’exemple des ritournelles de Proust qui est utilisé pour faciliter la compréhension de la métamodélisation permise par les cartographies schizoanalytiques. Finalement, la conceptualisation de la démocratie écosophique permet de synthétiser l’apport des précédents chapitres en montrant comment elle est un choix éthique envers la différence favorisant l’hétérogenèse en s’engageant dans la métamodélisation dissensuelle tel que Guattari l’exprime dans son ultime article. Sont alors mentionnés sa participation aux élections régionales de 1992 et son projet d’états généraux d’une écologie politique pluraliste.
La thèse aborde aussi plusieurs autres concepts de Guattari et comprend également des annexes détaillées proposant entre autres une biographie de Guattari, les récits biobibliographiques de ses dernières livres et une bibliographie analytique qui se veut exhaustive de son œuvre. Ce travail offre ainsi une analyse approfondie de la pensée de Guattari, mettant en lumière sa contribution à la théorie politique et son approche novatrice de l'écologie, tout en explorant son engagement dans divers mouvements écologistes et des gauches alternatives, en plus d’offrir une bibliographie qui a vocation à devenir la référence pour son œuvre
Full-thickness tracheal laceration managed conservatively: a case report
No full textAbstract Background Tracheobronchial injuries, which are rare complications of intubation, can be overlooked without a high degree of clinical suspicion. While traditionally managed surgically, recent literature proposes nonoperative management for low-risk injuries. Case presentation. This case illustrates a 56-year old Caucasian Canadian female with a grade IIIA injury successfully treated conservatively using an endotracheal tube and medical therapy. Consequently, it suggests that nonoperative management may be suitable for patients meeting specific criteria indicative of clinical stability. Conclusion These insights challenge the conventional surgical approach and emphasize the potential efficacy of conservative measures in selected cases of tracheobronchial injury
Excitatory and Inhibitory Cable Properties Controls the Transient Amplification of Electrical Stimulation
No full textNeuromodulation therapies such as deep brain stimulation have shown some clinical success in treating Parkinson's, epilepsy, essential tremor, and many other conditions. However, these devices primarily target the subcortex and treat a small subset of neurological disorders. To address these limitations, we investigate cortical stimulation as an alternative, focusing on the biophysical and network-level mechanisms that shape the brain's responses to electrical input.
This thesis investigates how excitatory and inhibitory cable properties influence the transient amplification resulting from electrical stimulation in the cortex. Cortical stimulation remains poorly understood, and debates persist about the biological processes involved in direct electrical stimulation. To better understand these responses, we developed a mathematical model grounded in the biophysical properties of neurons, combining axonal cable theory to emulate experimentally observed cortical phenomena.
We begin by analyzing recruitment through cable theory, and we derive a relationship between the intensity threshold and the axon diameter. Experimental studies (Micheva, Kristina D., et al., 2016) show that inhibitory axons in the cortex are larger in diameter compared to excitatory ones, resulting in a bias toward inhibitory recruitment. However, to promote excitatory recruitment, we assume that inhibitory axons, particularly those with larger diameters, are myelinated. Since myelinated axons require higher stimulus intensities to be activated, this assumption raises the activation threshold for inhibition, while favouring excitation. Therefore, the axonal cable properties in our model suggest that excitation is more readily recruited than inhibition.
Next, we develop the mean-field model, which begins with a network of intercommunicating excitatory and inhibitory neurons. We introduce two stimulation paradigms: the activation model, which focuses on the recruitment of antidromic axons and somas to initiate the input into our field model, and the depolarization model, which assumes direct electrical stimulation of neurons, leading them to depolarize in response to external extracellular voltage.
We find that both models elicit the same cortical responses from electrical stimulation. With fine-tuned parameters, both models exhibit transient amplification due to the excitatory-inhibitory imbalance in activation.
The cable properties of axons allow for the recruitment of excitatory and inhibitory neurons during electrical stimulation. The recruitment imbalance results in different network-level responses. In particular, our model demonstrates that these imbalances can lead to transient amplification, resulting in early excitatory activation followed by lagging inhibition that restores the network
Neuromonitoring with near-infrared spectroscopy (NIRS) in aneurysmal subarachnoid hemorrhage: A systematic review and meta-analysis
No full textAbstract Purpose Near-infrared spectroscopy (NIRS) is a non-invasive, real-time and continuous cerebral oximetry monitoring with potential applications in the management of aneurysmal subarachnoid hemorrhage (aSAH) and in the detection of delayed cerebral ischemia (DCI). The aim of this study was to evaluate the association between NIRS and outcome in aSAH and its diagnostic accuracy for DCI. Methods Systematic review and meta-analysis of studies involving adult aSAH patients monitored with NIRS during index hospitalization. Primary outcome was the functional outcome at 90 days or more. Secondary outcomes included any functional outcome, mortality and diagnostic accuracy for DCI. Random effects meta-analyses were performed, and for diagnostic accuracy, forest plots and random effects meta-analyses were used to determine pooled sensitivity, specificity, diagnostic odds ratios and to generate a receiver operating characteristic (ROC) curve. Results Of the 28,296 citations identified, 35 satisfied inclusion criteria. Three studies (202 patients) were included for meta-analysis of the primary outcome. Cerebral desaturation events or loss of autoregulation as detected with NIRS were associated with higher risks of unfavourable outcome at 90 days (RR 4.29 95% CI [2.10;8.79]). Significant associations were also observed with mortality (RR 4.24, 95% CI [2.43;7.41]). Diagnostic accuracy analysis demonstrated moderate sensitivity (0.85), specificity (0.65), and diagnostic odds ratio (10.42), with a receiver operating characteristic (ROC) curve area of 0.68. The certainty of evidence was moderate for the association between NIRS and patient outcomes, and low for its diagnostic accuracy in detecting DCI.The overall quality of evidence was limited by small sample sizes, high heterogeneity in study methods and patient populations, and potential publication bias. Conclusion Cerebral desaturation events and impaired autoregulation detected by NIRS are consistently associated with poor outcomes and mortality in aSAH. However, NIRS alone provides only moderate diagnostic accuracy for DCI, with a considerable risk of false positives. The evidence is weakened by methodological limitations, heterogeneous thresholds, and the absence of a universally accepted reference standard for DCI diagnosis. Importantly, no interventional data are available to demonstrate an effect on patient outcomes. While incorporation into multimodal neuromonitoring strategies appears promising, robust prospective trials are needed before NIRS can be reliably adopted in routine clinical practice
"Why are you here"?: American Jewish Activists Living in Israel-Palestine
No full textAs tensions between Israel and Palestine deepen, diaspora communities have become further polarised. Among the Jewish community, Jews living in America feel torn between two centres of Jewish life, America and Israel-Palestine. For left-wing Jews, particularly, engaging in Israeli-Palestinian politics feels like a moral obligation to transform the Jewish community (Kroll-Zeldin 2024). This thesis explores Jewish Americans residing in Jerusalem and engaging in anti-occupation activism and their desires to belong within the community after feeling disillusioned by their Jewish institutional upbringings. Activists seek to forge a community that meets their moral and ethical demands while navigating moral and ethical complications. Since the war that started on October 7th, 2023, the ground has shifted and become more polarised, leading activists, myself included, to seek alternatives. Within the activist community, I argue that at times they reproduce forms of exclusion. Outside of the activist community, as they work in partnership with Palestinians, I argue that sometimes deep relationships are not necessarily cared for