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Hybrid forecasting: blending climate predictions with AI models
No full text© Author(s) 2023.
This work is distributed under the Creative Commons Attribution 4.0 License.
Published by Copernicus Publications on behalf of the European Geosciences Union.UK Research and Innovation (grant nos. MR/V022008/1 and NE/S015728/1), the Swiss Federal Institute for Forest, Snow and Landscape Research (MaLeFix; Extremes), the Canada First Research Excellence Fund (Global Water Futures programme), the U.S. Army Corps of Engineers (USACE Institute for Water Resources), and the Science Foundation Ireland (grant no. SFI/17/CDA/4783).Peer ReviewedHybrid hydroclimatic forecasting systems employ data-driven (statistical or machine learning) methods to harness and integrate a broad variety of predictions from dynamical, physics-based models – such as numerical weather prediction, climate, land, hydrology, and Earth system models – into a final prediction product. They are recognized as a promising way of enhancing the prediction skill of meteorological and hydroclimatic variables and events, including rainfall, temperature, streamflow, floods, droughts, tropical cyclones, or atmospheric rivers. Hybrid forecasting methods are now receiving growing attention due to advances in weather and climate prediction systems at subseasonal to decadal scales, a better appreciation of the strengths of AI, and expanding access to computational resources and methods. Such systems are attractive because they may avoid the need to run a computationally expensive offline land model, can minimize the effect of biases that exist within dynamical outputs, benefit from the strengths of machine learning, and can learn from large datasets, while combining different sources of predictability with varying time horizons. Here we review recent developments in hybrid hydroclimatic forecasting and outline key challenges and opportunities for further research. These include obtaining physically explainable results, assimilating human influences from novel data sources, integrating new ensemble techniques to improve predictive skill, creating seamless prediction schemes that merge short to long lead times, incorporating initial land surface and ocean/ice conditions, acknowledging spatial variability in landscape and atmospheric forcing, and increasing the operational uptake of hybrid prediction schemes
Multiscale Transport and Osmotic Tolerance in Liver Cells and Tissues
Get PDFCryopreservation enables the storage of biological samples for later use while preserving all aspects of biological interest by cooling them to a temperature where chemical reactions are sufficiently slowed. However, there have been considerable challenges in preserving complex tissues and organs due to excessive ice formation, severe thermal stress, chilling, ischemic injury, and the osmotic stress caused by highly viscous cryoprotectants (CPA). To overcome these challenges, mathematical modeling approaches have proven effective in predicting cell and tissue responses to osmotic stress and developing an optimal method for loading and unloading CPA. Predicting optimal cryopreservation protocols requires an accurate estimation of cell volume, solute concentration, and water permeability parameters. A key bottleneck in this process is the requirement of careful measurement of these parameters from the cellular to the tissue scale and the difficulty of studying these in their native three-dimensional (3D) structures: little is known about the detailed responses of individual cells and nuclei in monolayers and tissues to anisosmotic media. Over the course of four projects, my study has mainly used two approaches to overcome these barriers. It focused on real-time monitoring of cellular morphometric parameters using modern four-dimensional imaging techniques and employed mathematical models for solute and water permeability estimation. In the first project, I characterized the osmotic behavior in HepG2 cells, which serve as a model for hepatocytes, and determined the mechanism of osmoregulation within these cells. I illustrate that HepG2 cells are non-ideal osmometers by showing the difference between the expected behavior of cells in anisosmotic environments and by making predictions about their volume regulation mechanisms. Second, I compared cell volume measurement techniques for adherent cell monolayers, which included using a calcein fluorescence quenching technique to investigate the volumetric responses of HepG2 monolayers. My follow-up study uses modern 3D imaging techniques to simultaneously measure real-time cell and nuclear volume changes in adherent cells in an aniosomotic medium, including during the addition and removal of CPA. My results demonstrate that both cells and nuclei regulate their volume in response to osmotic stress. Consequently, cells and nuclear permeability to water (Lp) and CPA (Ps) are inferred during perfusion with anisosmotic and CPA solutions for adherent cell monolayers. Thirdly, I show that osmotic damage is time dependent and that the flavonoid silymarin enhances resistance to osmotic stress and may improve cryosurvival in HepG2 cells. Finally, I extend the 3D imaging technique to track and quantify three dimensional changes in cell and nuclear morphology in response to anisosmotic medium. I then estimate the volume within complex liver tissue, specifically a precision-cut liver slice (PCLS). This method allows the quantification of the expansion and contraction of the whole PCLS during CPA equilibration, as well as the tracking of nuclei and cell volume. By demonstrating the nonideality of liver cells and the complex interplay between cytoplasm and nuclear volumes, we can inform biophysical models, which may have profound implications for our understanding of cell physiology and the mechanism of osmoregulation. Furthermore, the methods described in this study can be adapted to enhance cryopreservation strategies for adherent cells, other complex tissues, and organs. Altogether, this research contributes to the development of a new cryopreservation method for liver cells and tissues and will have a broad impact on the field of tissue transplantation and biomedical research
Dissecting Seed Shape in Lentil (Lens culinaris Medik.) with High-Throughput Phenotyping and Genome-Wide Association Studies
Get PDFSeed shape is an important trait for dehulling and splitting during the milling process of lentil. A high-throughput image-based phenotyping system was previously developed to provide direct metrics from single seeds. This study aimed to take this new, and more precise system, to phenotype and dissect lentil seed shape and identify new genetic markers for the lentil breeding program. To accomplish this, seed from 324 diverse genotypes that had been grown at six site-years in two major lentil growing environments (temperate and Mediterranean) were imaged. Significant differences were identified between seeds from temperate and Mediterranean macro-environments for four seed shape parameters: diameter, circularity (measure of uniformity of the seed edges), height (seed thickness), and plumpness. Each seed parameter had high heritability, suggesting a low environmental influence, which is also supported by an absence of significant correlations with phenological parameters or temperature. A stability analysis of the seed shape traits across the six site-years revealed that seed height has fewer stable lines when compared with circularity, diameter, and plumpness and that for each of these traits there is a range of stability, making some genotypes more stable than others across site-years. Genome-wide association studies were used to identify QTL for most seed shape traits, with diameter having the most consistent identification of significant QTL. The new phenotyping system used in this study coupled with multi-locus GWAS models achieved similar results when compared with previous studies, although it can help breeding programs identify new candidate genes with improved precision by extracting multiple traits like seed shape and seed color simultaneously
Breaking Bad News: Effective Communication in Cancer Diagnosis Disclosure
No full textThe abstract of this item is unavailable due to an embargo
Measuring and characterizing weak RSA keys across PKI ecosystem
Get PDFThe insecurities of public-key infrastructure on the Internet have been the focus of research for over a decade. The extensive presence of broken, weak, and vulnerable cryptographic keys has been repeatedly emphasized by many studies. Analyzing the security implications of cryptographic keys' vulnerabilities, several studies noted the presence of public key reuse. While the phenomenon of private key sharing was extensively studied, the prevalence of public key sharing on the Internet remains largely unknown. This work performs a large-scale analysis of public key reuse within the PKI ecosystem. This study investigates the presence and distribution of duplicate X.509 certificates and reused RSA public keys across a large collection containing over 315 million certificates and over 13 million SSH keys collected over several years. This work analyzes the cryptographic weaknesses of duplicate certificates and reused keys and investigates the reasons and sources of reuse. The results reveal that certificate and key sharing are common and persistent. The findings show over 10 million certificates and 17 million public keys are reused across time and shared between the collections. Observations show keys with non-compliant cryptographic elements stay available for an extended period of time.
The widespread adoption of Android apps has led to increasing concerns about the reuse of digital certificates. Android app developers frequently depend on digital certificates to sign their applications, and users place their trust in an app when they recognize the owner provided by the same certificate. Although the presence of cryptographic misuse has been acknowledged by several studies, its extent and characteristics are not well understood. This study performs a detailed analysis of code-signing certificate reuse across the Android ecosystem and malware binaries on a collection of over 19 million certificates and over 9 million keys extracted from PE files and Android applications collected over several years. The results reveal that despite the growing nature of the Android ecosystem, the misuse of cryptographic elements is common and persistent. The findings uncover several issues and enable us to provide a series of applicable solutions to the seen security flaws
Curlicue: Stories
Get PDFCurlicue is a collection of eight stories that examines anxiety in respect to loss, loneliness, and the coming of age. The stories are, in part, crafted from my own personal experiences and struggles with anxiety. I wanted the collection to reflect me as an individual, to the problems that I face with anxiety, which is why I chose to focus on characters and their relationships. Drawing inspiration from writers like Raymond Carver, Tobias Wolff, and Alice Munro, the stories focus on subtle, sometimes banal, every-day situations that are characteristic of realism. Alternating between flash and short story fiction, the collection aims to generate symptoms of anxiety that are not only discernible through the interiority and actions of the character but also through the implication of the narratives, the economy of words, the symbols layered throughout, and the tones of the stories. Curlicue attempts to share the discomfort of anxiety with its readers while also leaving room for moments of hope
Connecting Technology with Communities: The Case of Small Modular Reactors
Get PDFIndigenous people in northern and remote communities around the world share similar experience with energy systems. The history of energy development in those areas is based on the policy of ‘extractivism’ imposed by the ‘western’ world. This has led to the current situation where remote Indigenous communities often suffer from energy insecurity and energy poverty. Indigenous communities in Canada have been through transitions, not just in energy but other socio-economic sectors. Today these communities play an important role in the development of the energy profile for the country. Partnering with them to develop local clean energy production seems an obvious benefit to all parties. However, the record of these partnerships is poor, with some failing to produce the expected benefits and others failing to get off the ground at all. Recent policies push for accelerated energy transitions which create additional pressure where thorough and meaningful work with Indigenous partners is needed.
In this dissertation, I research clean energy development from northern, remote, and Indigenous perspectives within the context of sustainability transitions literature. I focus on the social context of clean energy innovation development in potential application to small modular reactors (SMRs). SMRs currently have momentum as a potential technology for decarbonizing power production with recent discussions of the use of microreactors in remote communities. Since SMRs have yet to be deployed, I first review the literature on clean energy projects in northern and remote communities and outline the common features of successful projects. Next, I focus on one of these features, the role of intermediary actors and organizations, and show how intermediaries have developed distinct storylines about SMRs within the larger narrative of SMR development and deployment in Canada. Finally, I study four case studies of renewable energy projects in Indigenous communities. Using interviews with community leaders, I describe their perspectives and interests in energy projects and compare them with government and industry partners’ perspectives. The results reveal a fundamental misalignment of expectations between Indigenous communities and their partners.
One of the central arguments of this dissertation is the importance of the role of Indigenous intermediaries, i.e., actors and platforms that sustain the momentum of transitions by linking actors, activities, and resources that can move easily between the communities and the larger energy production context. The work of Indigenous intermediaries reveals the need for the construction of a safe space where communities can frame the discussion within Indigenous worldviews and lived experience. I offer policy recommendations for how this space can be constructed and protected. Meeting this need can help in formulating policy around the successful deployment of small modular reactors (SMRs) or any other clean energy technology.
Innovative features of the dissertation include reflections on the challenges of applying the Euro-centric approaches in the sustainability transitions literature in non-European environments, including remote, northern and Indigenous communities; a systematic review of the lessons from renewable energy case studies from sustainability transitions literature, their practical application in the context of SMR development, and community-based case studies of clean energy projects in application to SMRs
Blooms and flows: Effects of variable hydrology and management on reservoir water quality
No full textThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
© 2023 The Authors. Ecosphere published by Wiley Periodicals LLC on behalf of The Ecological Society of America.Canada First Research Excellence Fund; Canada Foundation for Innovation; Mitacs; Buffalo Pound Water Treatment PlantPeer ReviewedFlow management has the potential to significantly affect ecosystem condition. Shallow lakes in arid regions are especially susceptible to flow management changes, which can have important implications for the formation of cyanobacterial blooms. Here, we reveal water quality shifts associated with changing source water inflow management. Using in situ monitoring data, we studied a seven-year time span during which inflows to a shallow, eutrophic drinking water reservoir transitioned from primarily natural landscape runoff (2014–2015) to managed flows from a larger upstream reservoir (Lake Diefenbaker; 2016–2020) and identified significant changes in cyanobacteria (as phycocyanin) using generalized additive models to classify cyanobacterial bloom formation. We then connected changes in water source with shifts in chemistry and the occurrence of cyanobacterial blooms using principal components analysis. Phycocyanin was greater in years with managed reservoir inflow from a mesotrophic upstream reservoir (2016–2020), but dissolved organic matter (DOM) and specific conductivity, important determinants of drinking water quality, were greatest in years when landscape runoff dominated lake water source (2014–2015). Most notably, despite changing rapidly, it took multiple years for lake water to return to a consistent and reduced level of DOM after managed inflows from the upstream reservoir were resumed, an observation that underscores how resilience may be hindered by weak resistance to change and slow recovery. Environmental flows for water quality are rarely defined, yet we show that trade-offs exist between poor water quality via elevated conductivity and DOM and higher bloom risk, depending on water source. Our work highlights the importance of source water quality, not just quantity, to water security, and our findings have important implications for water managers who must protect ecosystem services while adapting to projected hydroclimatic change
Variation in fitness and infection phenotype among strains of Borrelia burgdorferi emerging in Canada
No full textEvolutionary virulence theory is life history theory for pathogens that explains why pathogen-induced damage (virulence) to the host is adaptive. Virulence theory examines the relationships between three pathogen life history traits: within-host replication and pathogen abundance in host tissues, pathogen transmission, and the damage caused to the host by the pathogen (virulence). Pathogen abundance in host tissues is positively correlated with pathogen transmission to new hosts. Higher pathogen abundance in host tissues also leads to higher levels of host exploitation, which should increase the pathogen-induced mortality rate or virulence. Thus, there is a positive relationship between virulence and transmission, which represents a life history trade-off for the pathogen. By increasing its exploitation of the host, the pathogen obtains the benefit of more current transmission at the cost of a shorter duration of infection. If the relationship between virulence and transmission is one of diminishing returns, natural selection should favour the evolution of an an optimal value of virulence to maximize lifetime transmission. In summary, virulence theory allows us to understand the selective pressures influencing the evolution of pathogen life history traits.
Borrelia burgdorferi is a tick-borne spirochete bacterium that causes Lyme borreliosis, the most common tick-borne disease in the Northern Hemisphere. In North America, B. burgdorferi is commonly vectored by the black-legged tick Ixodes scapularis, which acquires the infection from competent reservoir hosts. Borrelia burgdorferi is comprised of genetically distinct strains. These strains coexist in the same tick and vertebrate host populations at different frequencies and are variable in their life history traits.
For this study, we investigated the relationships between the three canonical pathogen life history traits of pathogen abundance in host tissues, transmission, and virulence among 11 strains of B. burgdorferi. Mice (male and female Mus musculus C3H/HeJ) were experimentally infected by tick bite with 1 of the 11 strains. To measure lifetime host-to-tick transmission, mice were infested with I. scapularis larval ticks at days 30, 60, and 90 post-infection (PI). To track the spirochete population in the host over time, the spirochete load was estimated in ear biopsies at days 29, 59, and 89 PI using qPCR. The mouse serum IgG antibody response against B. burgdorferi was measured at days 28 and 97 PI. Mice were euthanized at day 97 PI and necropsy tissues (left ear, right ear, ventral skin, tibiotarsal joint, heart, bladder, and kidney) were tested for their spirochete loads by qPCR. Over the course of the infection, weight gain and ankle swelling were measured as possible virulence phenotypes. Mouse necropsy tissues (kidney, ventral skin, tibiotarsal joint, and heart) were also prepared for histopathology.
As expected, we found significant variation among the 11 B. burgdorferi strains in each of the three life history traits. As predicted by evolutionary virulence theory, we found a significant positive relationship between spirochete load in the mouse tissues and lifetime host-to-tick transmission. Our lab-based estimates of mouse tissue spirochete load and lifetime host-to-tick transmission were also significantly positively related to the frequencies of these strains in natural populations of I. scapularis ticks. Our study suggests a simple mechanism where strains that reach a greater abundance in the tissues of their host have greater transmission to feeding ticks and are therefore more common in nature. We did not find a relationship between virulence and the other pathogen life history traits. Instead, we found that the host immune response was positively related to our ankle swelling measure of virulence.
Finally, this experimental infection study used both male and female C3H/HeJ mice. To the best of our knowledge, we report here the first finding of a sex-specific difference in the abundance of B. burgdorferi in the tissues of a rodent host. This sex-specific difference was also found for transmission, where ticks that fed on male mice were more likely to be infected than ticks that fed on female mice. Females had a significantly stronger antibody response to B. burgdorferi, which is consistent with known sex-specific differences in immune responses. Interestingly, female mice had higher levels of carditis compared to male mice suggesting that the immune response rather than heart spirochete loads were responsible for this sex-specific difference in pathology
Fast Neutron SMR’s empowering Regional Isotope Ecosystems
No full textEcosystems will evolve around a multi-purpose Small Modular Fast Neutron Reactor and create an innovation-driven economy to become a local, national and international solution for reducing carbon-emissions and supplying high volume and high assay medical isotopes for many decades. This presentation includes a retrospective of the Canadian landscape, the path this decade of the currently developing landscape and what is on the horizon with Multi-purpose Small Modular Fast Neutron Reactors with the example of developing a Regional Isotope Ecosystem around the ARC-100 Sodium Fast Reactor deployment at the Point Lepreau Nuclear Generating site in New Brunswick