National Class Actions in Canada: Yet Another Call for Clarity and Coordination

Just as economic markets increasingly neglect Canada’s domestic borders, so too does the consequent infliction of harm. Not surprisingly, then, the national class action has emerged as a desirable vehicle for mass redress. Desirable, perhaps, but are national class actions constitutional? Distinguished Canadian scholars continue to construct persuasive arguments on both sides, meanwhile, courts continue to assume jurisdiction over national classes. Accordingly, this paper argues that while the permissibility of multijurisdictional class proceedings might make for an engaging debate, the apparent willingness of courts to certify national classes means that the path forward is not through academic discourse, but through the creation of realistic mechanisms of interprovincial judicial coordination

National Class Actions in Canada: Yet Another Call for Clarity and Coordination

Just as economic markets increasingly neglect Canada’s domestic borders, so too does the consequent infliction of harm. Not surprisingly, then, the national class action has emerged as a desirable vehicle for mass redress. Desirable, perhaps, but are national class actions constitutional? Distinguished Canadian scholars continue to construct persuasive arguments on both sides, meanwhile, courts continue to assume jurisdiction over national classes. Accordingly, this paper argues that while the permissibility of multijurisdictional class proceedings might make for an engaging debate, the apparent willingness of courts to certify national classes means that the path forward is not through academic discourse, but through the creation of realistic mechanisms of interprovincial judicial coordination

Zombie Vortex Instability. II. Thresholds to Trigger Instability and the Properties of Zombie Turbulence in the Dead Zones of Protoplanetary Disks

In Zombie Vortex Instability (ZVI), perturbations excite critical layers in stratified, rotating shear flow (as in protoplanetary disks), causing them to generate vortex layers, which roll-up into anticyclonic zombie vortices and cyclonic vortex sheets. The process is self-sustaining as zombie vortices perturb new critical layers, spawning a next generation of zombie vortices. Here, we focus on two issues: the minimum threshold of perturbations that trigger self-sustaining vortex generation, and the properties of the late-time zombie turbulence on large and small scales. The critical parameter that determines whether ZVI is triggered is the magnitude of the vorticity on the small scales (and not velocity), the minimum Rossby number needed for instability is $Ro_{crit}\sim0.2$ for $\beta\equiv N/\Omega = 2$, where $N$ is the Brunt-V\"ais\"al\"a frequency. While the threshold is set by vorticity, it is useful to infer a criterion on the Mach number, for Kolmogorov noise, the critical Mach number scales with Reynolds number: $Ma_{crit}\sim Ro_{crit}Re^{-1/2}$. In protoplanetary disks, this is $Ma_{crit}\sim10^{-6}$. On large scales, zombie turbulence is characterized by anticyclones and cyclonic sheets with typical Rossby number $\sim$0.3. The spacing of the cyclonic sheets and anticyclones appears to have a "memory" of the spacing of the critical layers. On the small scales, zombie turbulence has no memory of the initial conditions and has a Kolmogorov-like energy spectrum. While our earlier work was in the limit of uniform stratification, we have demonstrated that ZVI works for non-uniform Brunt-V\"ais\"al\"a frequency profiles that may be found in protoplanetary disks.Comment: Submitted to Ap

The Venture Capital Investment Bust: Did Agency Costs Play a Role? Was it Something Lawyers Helped Structure?

This Article examines the question of why venture capital firms would continue to raise technology funds, and then invest those funds, when they were certain that the business markets for such investments were overvalued preceding the “crash” of April 2000. We interviewed a number of venture capitalists, lawyers, entrepreneurs, and other industry observers in search of an explanation. The explanations offered by key decision makers for the observed investment behavior can be categorized as of three types of theories: agency cost theories, herd behavior and other cognitive bias theories, and non–agency cost theories. Agency cost theories suggest that the activity took place because of the divergence between the long-term reputational and other interests of fund general partners (venture capital firms), and the short-term interests of their limited partner investors. Herd behavior explanations apply herding theory to the general movement of venture capital firms, but fail to provide a satisfactory explanation for the direction of the “herd.” Non-agency cost theories include explanations premised upon gaming strategies by better-informed venture capitalists in the context of less-informed public markets at the end of the investment pipeline. All of the theories surveyed are problematic in at least some respects, and none fully explains the pattern of investment observed

THE ANALYSIS OF ANCIENT DNA: FROM MITOCHONDRIA TO PATHOGENS

Ancient DNA (aDNA) is arguably one of the most difficult science fields to work in due to the constant battle against contamination and degradation; however, it is also one of the most rewarding. aDNA researchers have consistently garnered interest the world over with their findings and sparking the curiosity of many who wish to know more about who we are as Homo sapiens. Mitochondrial DNA (mtDNA) and pathogen DNA were used in this dissertation to understand more about where populations came from, how they moved, and what their environment was like through the identification of their maternally inherited mtDNA and pathogens. This is a synthesis of my work and collaboration with other researchers both in lab and at the computer to add more data to the story of humankind

An interpretable machine learning workflow with an application to economic forecasting

[EN] We propose a generic workflow for the use of machine learning models to inform decision making and to communicate modelling results with stakeholders. It involves three steps: (1) a comparative model evaluation, (2) a feature importance analysis and (3) statistical inference based on Shapley value decompositions. We discuss the different steps of the workflow in detail and demonstrate each by forecasting changes in US unemployment one year ahead using the well-established FRED-MD dataset. We find that universal function approximators from the machine learning literature, including gradient boosting and artificial neural networks, outperform more conventional linear models. This better performance is associated with greater flexibility, allowing the machine learning models to account for time-varying and nonlinear relationships in the data generating process. The Shapley value decomposition identifies economically meaningful nonlinearities learned by the models. Shapley regressions for statistical inference on machine learning models enable us to assess and communicate variable importance akin to conventional econometric approaches. While we also explore high-dimensional models, our findings suggest that the best trade-off between interpretability and performance of the models is achieved when a small set of variables is selected by domain experts.Buckmann, M.; Joseph, A. (2022). An interpretable machine learning workflow with an application to economic forecasting. En 4th International Conference on Advanced Research Methods and Analytics (CARMA 2022). Editorial Universitat Politècnica de València. 275-275. http://hdl.handle.net/10251/18976127527

Leverage and Asset Bubbles: Averting Armageddon with Chapter 11?

An iconic model with high leverage and overvalued collateral assets is used to illustrate the amplification mechanism driving asset prices to 'overshoot' equilibrium when an asset bubble burst--threatening widespread insolvency and what Richard Koo calls a 'balance sheet recession'. Besides interest rates cuts, asset purchases and capital restructuring are key to crisis resolution. The usual bankruptcy procedures for doing this fail to internalise the price effects of asset 'fire-sales' to pay down debts, however. We discuss how official intervention in the form of 'super' Chapter 11 actions can help prevent asset price correction causing widespread economic disruption