VictorJuiz/thesis huggingface dataset:
Essays in the Macroeconomics of the Labour Market
Keywords: Displacement
Labor Market Transitions
Occupational Mobility
Recall

In this thesis, I combine three essays that examine earnings consequences of labour market transitions, using detailed data and search-theoretical frameworks. In the first chapter, I use German employer-employee data to explore long-run earnings consequences of mass layoffs. I find that workers who return to the employer that laid them off experience larger earnings losses, both in the short and in the long run. These larger earnings losses for these so-called recalled workers are driven by employment in the short run and by wages in the long run. Furthermore, recalled workers are more likely to lose their job again compared to workers who were re-employed at different employers. In the second chapter, I propose a job search model that explains these findings. In the model, I distinguish between workers who may be recalled soon and regularly unemployed workers. The model replicates the larger earnings losses experienced by recalled workers, despite these workers optimally choosing for this recall, thus suggesting that the recall was not a bad outcome. Indeed, decomposing the difference in earnings loss between recalled and non-recalled workers shows that the short-run difference is largely explained by selection, whereas the long-run effect is driven by recalled workers being more likely to lose their job again. The third chapter investigates the cyclicality of occupational mobility and its consequences for subsequent earnings and wages, distinguishing between workers who switch occupations through unemployment and workers who switch during a job-to-job transition. Using data from the Survey of Income and Program Participation, I find that the fraction of occupational switchers switching through unemployment is countercyclical, and while these workers generally do worse in terms of earnings than workers who make a job-to-job transition, their earnings and wage patterns may slightly improve in recessions. I then propose a job search model of occupational mobility in which I incorporate both types of occupational switches and show that the overall deterioration of earnings outcomes for occupational switchers in recessions is driven by a composition change towards switching through unemployment, dampened by the outcomes experienced by workers who switch occupations without switching employers.
Efficiency Automation in Aerodynamic Shape Optimization: Multimodal Dynamic Search Spaces
Keywords: Aerodynamic Shape Optimization
Computational Fluid Dynamics
Dynamic Geometry Control
Multimodality
Optimization

This work addresses two topics of relevance to efficiency and automation in aerodynamic shape optimization: multimodality and dynamic geometry control. Multimodality presents a challenge to efficiency and automation by introducing the risk of poor optimizer performance or inferior final geometries if not adequately addressed, necessitating careful selection of an optimization algorithm and considerable user insight. To shed light on this risk, a previously developed gradient-based multistart algorithm is leveraged to perform a large-scale parametric study of multimodality in aerodynamic shape optimization. This study reveals that multimodality is much more common in aerodynamic shape optimization than previously believed, that it is endemic in exploratory optimization problems, and that such multimodality is robust in the face of common optimization constraints. Traditional static geometry control methods offer a similar impediment to efficiency and automation by introducing performance trade-offs at various stages of optimization, enforcing arbitrary constraints on open-ended optimization, and necessitating foreknowledge of problem behaviour to design an effective control scheme. These shortcomings can be mitigated through dynamic geometry control, which partly automates the geometry control design process by refining the geometry control topology throughout optimization; such refinement can occur in a pre-determined fashion (as in progressive control) or more automatically using sensitivity information to guide refinement (as in adaptive control). Both methods are implemented in the context of axial and free-form deformation geometry control, and several novel contributions are made to the adaptive algorithm including several novel ``potential indicators" to rank candidate refinements, a new approach to the treatment of active constraints, and the application of these methods to a wider suite of problems than previously attempted. This work demonstrates that dynamic geometry control is effective, reducing required iterations to convergence by 50% or more, realizing reductions in final drag of up to 2% while using as little as 10% as many design variables as a well-designed static control scheme, all while reducing labour requirements on the user. These gains are demonstrated across a wide variety of problems, representative of detailed, preliminary, and exploratory problems often encountered in both academia and industry.
Functional Transcendence in Mixed Hodge Theory
Keywords: Ax-Schanuel
functional transcendence
mixed Hodge

The Ax-Schanuel theorem is a function field analogue of the Schanuel’s conjecture in transcendental number theory. Building on the works of Bakker, Gao, Klingler, Mok, Pila, Tsimerman, Ullmo and Yafaev, we extend the Ax-Schanuel theorem to mixed period mappings. Using this together with the Ax-Schanuel theorem for foliated principal bundles by Blázquez-Sanz, Casale, Freitag, and Nagloo, we furthur extend the Ax-Schanuel theorem to the derivatives of mixed period mappings. Linear subspaces in the Ax-Schanuel theorem are replaced by weak Mumford-Tate domains, which are certain group orbits of mixed Hodge structures. Likewise, algebraic subtori are replaced by a notion called weakly special subvarieties. We prove that if an irreducible analytic subset of the jet space of germs of local liftings of a mixed period mapping satisfies a certain property about the dimensions of this subset and its Zariski closure, then the projection of it lies in a proper weakly special subvariety. The proof uses o-minimal geometry, namely the definable Chow theorem and the Pila-Wilkie counting theorem. Preliminarily, we prove that the weak Mumford-Tate domains have complex structures, and that their real-split retractions can be decomposed into semisimple and unipotent parts. We also prove that the image of a mixed period mapping is contained in the weak Mumford-Tate domain that arises from the monodromy group of the variation.
The Current Shaping Modular Multilevel DC-DC Converter
Keywords: current shaping
high frequency
modular
multilevel dc-dc converter
power electronic transformer
solid state transformer

Modular multilevel converters (MMCs) for dc applications require an internal circulating ac current to balance the charge of the voltage source module capacitors (VSM). While the frequency of this circulating ac current can be freely chosen, in state-of-the-art MMC structures, this frequency is typically limited to 100s of Hz due to the presence of large string inductors and the high number of switching operations, thereby requiring significant ripple power to be filtered by large VSM capacitors. In this thesis, a novel energy transfer mechanism for dc applications is introduced which is unique in that it employs a current source submodule (CSM) to directly control the circulating ac current of the converter, enabling the frequency of the circulating ac currents to be increased by at least two orders of magnitude. This results in a commensurate reduction in VSM capacitor size compared to state-of-the-art MMCs. Based on this current shaping mechanism, several converter structures are proposed to target a wide range of dc applications including applications requiring isolation, high voltage conversion ratios, and bidirectional operational capability. In each of the proposed converter topologies, only a fraction of the VSMs are required to be switched in a given operating cycle enabling a frequency multiplier effect to occur whereby the effective frequency seen by the magnetics of the converter, as well as the VSM capacitors, is much greater than the switching frequency of the individual VSMs. The core ideas of this thesis are validated through experimental work which is performed using a laboratory-scale prototype based on SiC power devices. Peak efficiencies of up to 97.1% were achieved at an effective operating frequency of 50 kHz. The experimental work demonstrates that converters based on this energy transfer mechanism enable substantive converter volume and cost reduction due to a reduction in capacitive and inductive storage requirements.
Bearing the Weight (of stigma): Examining Weight Stigma, Body Image, and Physical Activity in Adolescents
Keywords: Adolescents
Body image
Physical activity
Self-conscious emotions
Weight stigma

This research program examined the associations among weight stigma, body image, and physical activity in adolescents using three studies. Given the predominance of cross-sectional research that has investigated these associations, Studies 1 and 2 aimed to better understand the associations among weight stigma, body image, and physical activity using longitudinal and time-varying methodologies. Study 1 (n = 576) used a longitudinal design to assess the reciprocal and prospective associations between body-related self-conscious emotions (shame, embarrassment, authentic pride) and physical activity behaviour over three years in adolescents. Findings indicated that body-related self-conscious emotions at age 14-15 predicted physical activity behaviour one year later. In turn, physical activity behaviour predicted body-related shame and authentic pride another year later. Study 2 (n = 97) used a daily diary approach to explore the between- and within-person associations among experienced weight stigma, internalized weight stigma, and body-related shame, embarrassment, and pride over five days. Higher levels of experienced and internalized weight stigma on average were associated with greater odds of reporting body-related shame and embarrassment. Within-person levels were not associated with any body-related self-conscious emotions, and between-person levels of experienced and internalized weight stigma were not related to odds of reporting body-related pride. Informed by theoretical tenets and Studies 1 and 2, Study 3 (n = 311) tested an integrated and novel model examining the associations among weight stigma (experienced, internalized), body image (body-related shame, embarrassment, authentic pride, body appreciation) and physical activity in adolescents. Partial support for the integrated model was noted, such that higher experienced weight stigma was indirectly associated with lower levels of resistance training through higher internalized weight stigma and lower body-related authentic pride. In addition, higher experienced weight stigma was indirectly associated with higher negative body image and lower positive body image through higher internalized weight stigma. Collectively, these findings provide more comprehensive insight into the negative psychological and behavioural consequences of experienced and internalized weight stigma, and advance understanding of these relationships among the understudied adolescent population. Findings from this research program have implications for individual and system-level mechanisms that should be targeted to foster physical activity in adolescents who experience and internalize weight stigma.
Trip Reservation and Intelligent Planning (TRiP) for a Hyper-congestion-free Traffic System: In the Context of Pervasive Connectivity, Driving Automation and MaaS
Keywords: algorithm
big data
control
intelligent
reservation
traffic systems

In most cities worldwide, demand for travel exceeds the existing limited road capacity, which causes extended hours of hyper-congestion every day. Hyper-congestion starts when and where demand exceeds capacity on a link, a road or an area, causing capacity loss and severe performance degradation. In this thesis, we design and develop a proof-of-concept system for a trip-level, link-based, in-advance trip reservation and intelligent planning system, dubbed “TRiP”. TRiP is a network-wide methodological system and software platform that facilitates the pacing of travel demand into the existing road network without exceeding the link-level capacity. The system is intended for real-time application, using a dynamic, disaggregated, spatiotemporal, in-advance reservation approach. This thesis introduces three different interconnected pillars. The first is TRiP Abstraction (TRiNAT), which is a set of network abstraction tools developed to facilitate micro traffic management systems. The second pillar is TRiP Assignment (TRiFree), which is a novel traffic assignment algorithm for trip-level, link-based, in-advance reservation traffic control systems that aim to keep all road links hyper-congestion-free. TRiFree, coupled with TRiNAT and a frontend reservation app, create the third pillar: the Trip Reservation and Intelligent Planning (TRiP) platform.To ensure the scalability of the proposed methodology to practical city and region sizes, TRiP was tested on the Toronto, Canada, road network, which includes more than 8,434 road links and serves more than 501,800 vehicles during the peak of the weekday morning commute. Our results show a very promising reduction in total travel time of 18.9-26.6% and a reduction in total travelled distance of 0-2%. The simulation results of the various scenarios outperform existing techniques and introduce a holistic robust solution for enjoying a hyper-congestion-free road network. Unlike other propositions in the literature, TRiP is scalable for larger road networks. Therefore, this thesis offers a major contribution to state-of-the-art and state-of-the-practice traffic control systems.
"We are Stories, Not Labels:" Anishinaabekweg Childrearing Experiences
Keywords: Anishinaabeg
First Nations
Indigenous Health
Labelling Theory
Motherhood Studies

First Nations mothers are subject to various colonization attempts, including labelling as deviant parents, both in historical and contemporary contexts. Through the application of a micro-lens to one Anishinaabeg community, known as Opwaaganisiniing or the Red Rock Indian Band, in Northern Ontario, this research 1) highlights how Euro-Canadian labels, both past and present, have impacted childrearing and 2) uncovers resistant and persistent Anishinaabe mothering principles and practices. Decolonizing Praxis and Indigenous Methodology supplement the western theoretical approach of Labelling Theory. Labelling Theory has never been applied to Indigenous communities; however, it can be useful to describe how dominant societal labels can be damaging (causing shame and stigma) yet inversely empowering (developing resistance) for marginalized peoples. An archival study looked at historical government and religious documents to determine the historical labels applied to people in the community, and 14 Indigenous female parents were recruited from members of the Red Rock Indian Band to determine the contemporary labels that exist today. A conversational methods approach was used to elicit labels and stories from the parents. Indigenous narrative methods were undertaken to draw out meaning from the stories and anecdotes told by the parents. Despite the persistence of historical labels, it was found that contemporary parents use kinship and reclamation to resist these labels.
The Origins of the Herbarium of Pseudo-Apuleius
Keywords: Ancient History
Medieval History
Science History

The Herbarium of Pseudo-Apuleius is a late antique text describing the medicinal uses of 131 plants. This herbal was a popular medical work of early medieval western Europe, and the text therefore serves as a valuable representation of the medical beliefs and practices of the period. Despite the herbal’s significant presence in medieval Europe, most aspects of the herbal’s origins, such as the text’s original author, remain mysterious, while the theories about the herbal’s creation have been based on supposition and require reevaluation. This dissertation examines three aspects of the herbal that have need of reassessment: the text’s location of composition, the text’s date of composition, and the original intent of the work.The thesis demonstrates that the evidence used to support the common scholarly consensus for dating and locating the origin of the Herbarium in fourth-century North Africa requires reassessment, and argues that the intrinsic evidence of the text and applied source criticism suggests a much broader area of the Mediterranean (with some evidence for Italy), and a potentially earlier date. Using the preface as a framework for discussion, this dissertation also examines the herbal’s medical content and demonstrates how various aspects of the text, such as the herbal’s medical epistemology, align with the preface’s claims and also with the late antique genre of the practical medical handbook. Moreover, analysis of the herbal’s format and organization suggest elements of learned medicine beyond the level of a practical or amateur handbook. Finally, this dissertation offers a modern English translation of the herbal, the Latin version of which has never been translated into modern English.
Synthesis and Analysis of Two-dimensional Surface Phases in the Bi/Si(111) System by Scanning Tunneling Microscopy and Density Functional Theory
Keywords: Bi/Si(111)
DFT
STM

The Bi/Si(111) surface reconstruction is an attractive two-dimensional (2D) surface phase due to its compatibility with current Si-based electronic industry and due to its extraordinary Rashba spin splitting feature favorable for spintronics fabrication. However, detailed defect analysis and quantum dot creation in this system have not been reported. Here, using scanning tunneling microscopy (STM) and density functional theory (DFT), defects, quantum states and phase transformation mechanisms of the Bi/Si(111) system and the Pb/Bi/Si(111) system are studied separately. First, bias dependence and defects in the Bi/Si(111) √3×√3 β-phase are analyzed. It is confirmed that the honeycomb pattern at low-bias empty states and a hexagonal-closest-packed pattern at high-bias empty states originate from the Bi px, py states and Bi, Si overlapped states outside bulk bandgap, respectively. Analysis of the defect images and their associated densities of states provides further insight into the electronic structure of the surface. Second, crystal structure and quantum well states (QWSs) of the Pb/Bi/Si(111) 2D phase are researched. The atomic structure of the system is confirmed by STM images combined with DFT calculations. QWSs and a sizable Rashba band splitting are predicted with the latter comparable to what is found in other semiconductor heterostructures and an order of magnitude higher than that in Pb/Si(111) QWSs. Finally, quantum dot states (QDSs) are discovered in the √3×√3-Bi/Si(111) surface phases. The structure, energy dispersion, and size effect on the electronic states of the QDs are measured and verified. As-created QDs can be manipulated with a dot size down to 2 nm via Bi phase transformation, which in turn is triggered by thermal annealing at 700K. The transition mechanism is also supported by DFT calculations, and an empirical analytical model is developed to predict the transformation kinetics.
Patterns of Species Co-occurrence, Null Models, and the Influence of Biotic and Abiotic Factors: A Species Pairwise Approach
Keywords: aquatic ecology
habitat size
null model analysis
Ontario lakes
Species co-occurrence patterns
trait-based analysis

How natural communities are structured and what factors influence such structure has been a pervasive subject in ecology for more than one century. Among several approaches used to determine the structure of communities, species co-occurrence analysis has been a subject of controversy since the classical debate between Diamond and Connor-Simberloff. Their main contrasts were whether ecological communities differed from random groupings of species, the role biotic factors had in generating the observed assemblage patterns, and the methods to discern structures of communities different from random (null models). Here, my main goals were to improve approaches to species co-occurrence analysis, to improve our ability to discern whether communities are structured non-randomly, and to extend them to testing hypotheses related to ecological mechanisms. First, I analyzed co-occurrence patterns using a species pairwise approach, different from the typical whole-community approach, to discern the relationship between multiple species of lake fishes across thousands of lakes in Ontario. Specifically, I tested whether the co-occurrence patterns observed across multiple species pairs from several different watersheds exhibit consistent patterns. I used subsets of species to test specific hypotheses related to the roles of predation, competition, and environmental filtering in structuring fish communities. Following, I examined the influence of habitat size on the observed co-occurrence patterns. I compared species co-occurrence patterns across different categories of lake area and depth to determine whether and how these variables affected the associations observed among multiple species pairs. Finally, I determined whether species-pair associations can be predicted from simple ecological traits. I analyzed the relationship between three biologically relevant traits (body size, temperature preference and trophic level) and the co-occurrence values observed between each species pair. I detected a significant effect of temperature preference and trophic level on the observed co-occurrence patterns. Unexpectedly, body size did not exhibit a significant effect on the co-occurrence patterns. My research showed the strong effect of interspecific predation on community composition, that signals of non-random community assembly are strongly dependent on the abiotic conditions, that analyses at the whole-community level may dilute underlying ecological signals, and that species co-occurrence patterns reflect differences in species traits.