The University of Western Ontario
  • London, Ontario, Canada
Recent publications
Data provenance is any information about the origin of a piece of data and the process that led to its creation. Most database provenance work has focused on creating models and semantics to query and generate this provenance information. While comprehensive, provenance information remains large and overwhelming, making it hard for data provenance systems to support data exploration. We present a new approach to provenance exploration that builds on data summarization techniques. We contribute novel summarization schemes for the provenance of aggregation queries and techniques for the fast generation of these summarization schemes. We introduce two types of summaries for aggregate queries. Impact summaries take into account the impact of specific groups of tuples in the provenance of the query on an aggregate result, and comparative summaries allow users to compare the provenance of two aggregate results. We also present algorithms for efficient computation of these summaries, implement optimizations using data sampling and feature selection, and conduct experiments and a user survey to show the feasibility and relevance of our approaches.
In this article, a numerical inverse Laplace transform (NILT)-based algorithm is used to efficiently approximate key characteristics of coupled high-speed VLSI interconnects, such as 50% delay, overshoot, and peak crosstalk. Through the use of a variable (LC or RC) modal decoupling technique, matrix inversion at each time point and pole of the numerical inverse Laplace formula is computed on a diagonal matrix, allowing for minimal computation times at the cost of a slight reduction in accuracy. The proposed methodology independently solves the modal voltage response at each time point, pole, and line allowing for parallel computation resulting in further speed up. In addition, the order of the NILT approximation can be modified depending on the speed and accuracy needed. Four numerical examples of coupled interconnects are presented to evaluate the accuracy and computational efficiency of the proposed methodology. Overall, the NILT-based algorithm provides useful approximations of the time-domain response, while being significantly faster than SPICE.
Osteoarthritis (OA) is a progressive disease, involving the progressive breakdown of cartilage, as well as changes to the synovium and bone. There are currently no disease-modifying treatments available clinically. An increasing understanding of the disease pathophysiology is leading to new potential therapeutics, but improved approaches are needed to deliver these drugs, particularly to cartilage tissue, which is avascular and contains a dense matrix of collagens and negatively charged aggrecan proteoglycans. Cationic delivery vehicles have been shown to effectively penetrate cartilage, but these studies have thus far largely focused on proteins or nanoparticles, and the effects of macromolecular architectures have not yet been explored. Described here is the synthesis of a small library of polycations composed of N-(2-hydroxypropyl)methacrylamide (HPMA) and N-(3-aminopropyl)methacrylamide (APMA) with linear, 4-arm, or 8-arm structures and varying degrees of polymerization (DP) by reversible addition fragmentation chain-transfer (RAFT) polymerization. Uptake and retention of the polycations in bovine articular cartilage was assessed. While all polycations penetrated cartilage, uptake and retention generally increased with DP before decreasing for the highest DP. In addition, uptake and retention were higher for the linear polycations compared to the 4-arm and 8-arm polycations. In general, the polycations were well tolerated by bovine chondrocytes, but the highest DP polycations imparted greater cytotoxicity. Overall, this study reveals that linear polymer architectures may be more favorable for binding to the cartilage matrix and that the DP can be tuned to maximize uptake while minimizing cytotoxicity.
Over two hundred municipalities now offer online voting in Ontario, Canada, representing one of the largest deployments of digital elections worldwide. Many have eliminated the paper ballot altogether. Despite this, no provincial or federal-level standards exist. This gap leaves local election officials to create and apply their own cybersecurity requirements with varying degrees of success. Until a standard can be developed and adopted, we turn to perhaps the most natural and immediate stand-in: The Council of Europe’s (CoE) standards for e-voting. We use this baseline to present the first standards-based analysis of online voting practices in Ontario. Our results find the province is broadly non-compliant , with only 14% of the CoE’s 49 standards and 93 implementation guidelines categorized as fully met. We summarize these differences and identify areas for improvement in the hope of underscoring the need for domestic e-voting standards.
Despite being one of the biggest international users of online voting with two decades of use, Canada has tended to use non-verifiable online voting systems. This has prompted concern about the verification of election results and potential impacts on public and administrator confidence in elections and democracy. In the 2022 Ontario municipal elections, however, about 9% of municipalities offered the option of individual verifiability to online voters. This article draws upon the experiences of two local governments of different sizes, resources, capacity, and online voting histories - Ignace and Markham - and their vendors to understand the considerations and challenges that come with the introduction of verifiability mechanisms in local elections. We identify deterrents to implementation and possible solutions to see an increase in uptake and improve the integrity of local elections.
Energy leapfrogging (i.e., skipping non-renewable grid infrastructures to micro-grid renewable sources) has been promoted by researchers and politicians as a solution in fighting against climate change and for access to electricity in less developed countries. Despite research on its potential, quantitative measurement of leapfrogging is still required to determine those nations who have utilized energy leapfrogging's promise. In this study, we present a quantitative analysis using World Bank Open Database data from 2000 to 2015, creating an aggregated leapfrogging estimate (ALE) through renewable energy consumption (i.e., percentage of total energy consumption) and access to electricity (i.e., percent of total population with access). We defined the ALE by subtracting (renewable consumption % in 2000 / access to electricity % in 2015) from (renewable consumption % in 2015 / access to electricity in 2000). We included only countries whose renewable energy consumption increased during the study interval. Low-income countries collectively leapfrogged more than other income groups. Somalia (48.11), Togo (3.05), Eswatini (2.76), and Timor-Leste (1.04) all had ALE values greater than 1 (range: 1.7 × 10⁻⁵–48.11). We then conducted a policy analysis of these countries, confirming that all four had implemented renewable energy policies to create access to electricity. Our ALE accurately determined countries with energy leapfrogging, uniquely incorporating access to electricity, consistent with the fundamental purpose of leapfrogging as a strategy to increase access. Future studies are needed to understand why low-income countries with low ALEs and access to electricity failed to leapfrog in the past. Future studies are also required to design prospective quantitative statistical models predicting the outcomes of leapfrogging strategies.
Plain Language Summary Hydrogen is the most abundant element in the universe and is also the major constituent in the giant plants (Jupiter, Saturn, Uranus and Neptune) in the solar system. Although most of the surface temperatures of those giant planets are colder than Earth's, their interior temperatures are actually able to reach several thousand degrees Kelvin. The heat flows within these giant planets are very active, while knowledge of heat conduction and propagation are largely unknown. This study investigates the high‐pressure thermal conductivity of H2 at room temperature and high temperature conditions. Our results show that the liquid H2 exhibits low thermal conductivity, in the range of 0.7–1.1 W m⁻¹ K⁻¹ at high pressures and room temperature. However, appearance of solid H2 will increase thermal conductivity significantly and reach ∼27 W m⁻¹ K⁻¹ at 60.2 gigapascals and room temperature. Based on our model, the low thermal conductivity of liquid H2‐He mixture may suppress the heat loss of the giant planets and explain why their surfaces are cold, but interiors are hot.
The efferent and afferent effects of the vagus nerve on the developing brain have remained enigmatic. Here we review the evidence of such effects on microglial plasticity in the sheep model of human fetal development, one of the most recognized and deployed models of human fetal physiology. We show that vagotomy alters microglial phenotype and that this effect is hormetic under conditions of mild systemic inflammation, as may occur antepartum with chorioamnionitis. We present the methodology to assess not only biomarker-based microglial activation (Iba-1), but also the morphometric features of the microglia. Together, these assessments provide a more comprehensive toolbox of glial phenotypical characterizations, especially in the context of investigating the locoregional vagal control of glial function. The presented findings support the earlier discoveries in preclinical and clinical models of adult physiology whereby vagotomy appeared neuroprotective for Parkinson’s, explained, at least in part, by the effects on microglia. In addition, we present the approach to measure and the findings on regional cerebral blood flow changes in relation to vagus nerve manipulation. Together, the body of evidence underscores the importance of both the efferent and the afferent vagal pathways, via the vagus nerve, in the programming of microglial phenotype in the developing brain. The significance of these relationships for the development and treatment of early susceptibility to neuroinflammatory and neurodegenerative disorders in later life requires further studies.
Anorexia Nervosa (AN) is widely considered to be a bodily disorder accompanied by unrealistic perceptions about one’s own body. Some researchers thus have wondered whether deficits in interoception, a conscious or non-conscious sense of one’s own body, could be a primary cause of AN. In this paper, we make the case that rather than interoception being a primary cause, deficits in interoception may occur as by-products of emotions that arise upstream in the pathogenesis of AN and interact with feelings of a loss of self-control. We consider interoception, emotion, and self-control as a dynamical triad involved in the explanation of AN, with emotions as the central aspect of their interactions. We begin with a critical analysis of recent empirical literature on AN and differentiate three types of interoceptive processes. We then consider the role of self-control in AN. We go on to evaluate recent empirical and philosophical work on the role of emotions in AN and assess their importance in both interoception and self-control dynamics. We develop a testable integrative model that we believe best captures how self-control, emotional and interoceptive processes causally interact in the pathogenesis of AN. In this model, AN behaviors are not caused by interoceptive abnormalities, but rather interact with changes in emotional regulation and feelings of loss of self-control, subsequently leading to interoceptive deficits downstream. To capture a later stage in the pathogenesis of AN, we show how AN behaviors are maintained as a result of feedback among components in the model. We briefly explain future plans to further complement the model using a semi-structured interview to probe patient perspectives in AN. To develop a more valid understanding of AN, this model will have to be integrated into pluralistic approaches that include patient perspectives.
has been conducted on the influence of computational thinking (CT) dispositions on students' mathematics performance and engagement at the secondary or junior high school level.Limited research This study aims to bridge this research gap by developing CT-integrated mathematics lessons that incorporate CT-focused problem-solving and modeling in mathematics education. The study was conducted in a secondary school in Singapore, where students engaged in a mathematics modeling task while learning the four pillars of CT. To investigate the impact of integrating CT dispositions on student engagement and mathematics performance, a one-group posttest design together with a survey was administered. Mixed research methods were employed. Structural Equation Modeling analysis revealed that CT dispositions could enhance students' mathematics performance by fostering greater engagement in math, although a direct effect of CT disposition on mathematics performance was not observed. Additionally, interviews with students highlighted their positive dispositions towards CT, including a sense of capability, inclination, and sensitivity in utilizing CT for the modeling task and other contexts.
The coronavirus disease (COVID-19) pandemic and resulting restrictions on physical access to long-term care homes culminated in health declines for older adults living there and their families. Knowledge gaps exist regarding maintaining social connectedness when physically separated. The study aimed to explore family members’ perceptions of the impact that restrictions on physical access to long-term care homes had on the experience of social connectedness between family members and older adults living in long-term care. The method used was a qualitative description, using in-depth semi-structured interviews. Themes arising from inductive qualitative content analysis of 21 interviews with family members included: (a) lack of connection threatening mental, emotional health, and physical health; (b) navigating trust in the unknown; (c) feelings of stress and anxiety for family members; and (d) technology – an asset, but not for everyone. Study findings suggest more emphasis should be placed on supporting social connections between older adults and their families in the context of long-term care beyond COVID-19.
Many human activities contaminate terrestrial and aquatic environments with numerous chemical pollutants that not only directly alter the environment but also affect microbial communities in ways that are potentially concerning to human health, such as selecting for the spread of antibiotic-resistance genes (ARGs) through horizontal gene transfer. In the present study, metagenomes available in the public domain from polluted (with antibiotics, with petroleum, with metal mining, or with coal-mining effluents) and unpolluted terrestrial and aquatic environments were compared to examine whether pollution has influenced the abundance and composition of ARGs and mobile elements, with specific focus on IS26 and class 1 integrons ( intI 1). When aggregated together, polluted environments had a greater relative abundance of ARGs than unpolluted environments and a greater relative abundance of IS26 and intI 1. In general, chemical pollution, notably with petroleum, was associated with an increase in the prevalence of ARGs linked to multidrug efflux pumps. Included in the suite of efflux pumps were mexK , mexB , mexF , and mexW that are polyspecific and whose substrate ranges include multiple classes of critically important antibiotics. Also, in some instances, β-lactam resistance (TEM181 and OXA-541) genes increased, and genes associated with rifampicin resistance (RNA polymerases subunits rpoB and rpoB2 ) decreased in relative abundance. This meta-analysis suggests that different types of chemical pollution can enrich populations that carry efflux pump systems associated with resistance to multiple classes of medically critical antibiotics. IMPORTANCE The United Nations has identified chemical pollution as being one of the three greatest threats to environmental health, through which the evolution of antimicrobial resistance, a seminally important public health challenge, may be favored. While this is a very plausible outcome of continued chemical pollution, there is little evidence or research evaluating this risk. The objective of the present study was to examine existing metagenomes from chemically polluted environments and evaluate whether there is evidence that pollution increases the relative abundance of genes and mobile genetic elements that are associated with antibiotic resistance. The key finding is that for some types of pollution, particularly in environments exposed to petroleum, efflux pumps are enriched, and these efflux pumps can confer resistance to multiple classes of medically important antibiotics that are typically associated with Pseudomonas spp. or other Gram-negative bacteria. This finding makes clear the need for more investigation on the impact of chemical pollution on the environmental reservoir of ARGs and their association with mobile genetic elements that can contribute to horizontal gene transfer events.
Globally, it is estimated that 245 million women and girls aged 15 and over have experienced intimate partner violence (IPV) in the past 12 months. Moreover, research has highlighted the disproportionately high prevalence of IPV victimization among pregnant women. IPV can have serious health implications for women and their infants, yet little is known about maternal health-related decision-making by mothers exposed to IPV. To this end, the purpose of this scoping review was to examine what is known regarding health-related maternal decision-making among perinatal women in the context of IPV. Using Arksey and O’Malley’s framework, five electronic databases were searched, resulting in 630 articles. Eligible articles were primary studies written in English, included participants who experienced IPV at any time in their life, and reported results focused on maternal health-related decision-making in the context of IPV. Thirty-six articles were screened by the review team, resulting in seven included articles. Three main themes emerged regarding health-related maternal decision-making by mothers experiencing IPV, including suboptimal breastfeeding practices, under-utilization of maternal and child health services, and poor adherence to medical recommendations/regimens that impact health-related outcomes for mother and child. The well-established risk of poorer health outcomes among women experiencing IPV, alongside the findings of this scoping review, calls for further research specifically addressing health-related decision-making among perinatal women who experience IPV.
Purpose This study is the second part of a cross-sectional questionnaire aiming to identify Canadian physiotherapists needs and strategies for physiotherapy associations to improve cultural competence in physiotherapy. Methods We conducted a descriptive qualitative analysis of one open-ended question of a cross-sectional questionnaire. We used inductive thematic analysis to develop and modify codes as concepts emerged. Inductive analysis was used to develop the codebook from the qualitative finding of the research study. Results We received a total of 806 responses, and of those individuals, 485 provided one to three suggestions as part of the open-ended question. We identified two major themes from our open-ended question: (1) education and (2) institutional change. There were four subthemes categorized under education: (1) Diversity, Equity, Inclusion (DEI) training opportunities, (2) resources, (3) accessibility to education, and (4) representation within educational resources. Institutional change was categorized into three subthemes: (1) advocacy, (2) support, and (3) representation in leadership. Conclusions The results of this questionnaire act as a meaningful and necessary call to action to key stakeholders in the physiotherapy profession. Clinical Impact There is a need for educational institutions, regulatory bodies, and associations to re-evaluate policies surrounding cultural competence to improve the delivery of culturally safe healthcare.
Iran’s diverse climate and topography lead to variable precipitation distribution over different time scales. This study examines daily rainfall distribution across 37 Iranian synoptic stations for 53 years (1966–2018) using the daily precipitation concentration index (CI) and Shannon’s entropy (H). The analysis reveals significant insights into precipitation patterns and their implications. The concentration index (CI) highlights irregular daily precipitation, particularly along the Persian Gulf and Caspian Sea coastlines, and in southeastern Iran, where CI values range from 0.58 to 0.72. In contrast, Shannon’s entropy indicates higher entropy in northern and northwestern Iran, reflecting more uniform northwest rainfall (entropy values 6.48 to 11.63), while entropy decreases from northwest to south and southeast, indicating varying levels of precipitation evenness. The Lorenz asymmetric coefficient (LAC) indicates uneven rainfall distribution, characterized by light rain in the west/northwest and heavy rain elsewhere. The interplay between diminished precipitation, heightened entropy, and increased rainfall variability contributes to an elevated likelihood of droughts and flooding in the southern regions. For instance, regions like the Persian Gulf coast have CI values of 0.71, indicating moderate-high rainfall concentration. In the north, where CI values range from 0.57 to 0.71, amplified rainfall, entropy, and variability enhance the risk of flooding. Notably, the Shannon entropy index responds more significantly to changes in rainfall uniformity compared to increased daily precipitation classes, thereby significantly impacting the concentration index (CI). These findings provide valuable insights into the spatial and temporal dynamics of precipitation, with implications for risk assessment, and water resource management.
About half of the lunar meteorites in our collections are feldspathic breccias. Acquiring geochronologic information from these breccias is challenging due to their low radioactive‐element contents and their often polymict nature. We used high‐spatial‐resolution (5 μm) NanoSIMS (nanoscale secondary ion mass spectrometry) U‐Pb dating technique to date micro‐zircons in the lunar feldspathic meteorites Dhofar 1528 and Dhofar 1627. Three NanoSIMS dating spots of two zircon grains from Dhofar 1528 show a discordia with an upper intercept at 4354 ± 76 Ma and a lower intercept at 332 ± 1407 Ma (2 σ , MSWD = 0.01, p = 0.91). Three spots of two zircon grains in Dhofar 1627 define a discordia with an upper intercept at 3948 ± 30 Ma and a lower intercept at 691 ± 831 Ma (2 σ , MSWD = 0.40, p = 0.53). Both samples likely experienced shock metamorphism caused by impacts. Based on the clastic nature, lack of recrystallization and the consistent U‐Pb and Pb‐Pb dates of the zircons in Dhofar 1528, the U‐Pb date of 4354 Ma is interpreted as the crystallization age of its Mg‐suite igneous precursor. Some of the Dhofar 1627 zircons show poikilitic texture, a crystallization from the matrix impact melt, so the U‐Pb date of 3948 Ma corresponds to an impact event, likely the Imbrium basin‐forming event. These data are the first radiometric ages for these two meteorites and demonstrate that in situ (high spatial resolution) U‐Pb dating has potential for extracting geochronological information about igneous activities and impact events from lunar feldspathic and polymict breccias.
Among the important geological attributes of the small Cumbraes Basin in the southwestern off-shore Midland Valley of Scotland, the 4 km-long, fragmented but well-exposed section through the Devonian-Carboniferous boundary sequence in southern Great Cumbrae island ranks highly. In a continuous short stretch of the south and west coasts, large portions of this sequence are superbly preserved in tide-washed strandline surfaces and in old post-glacial sea cliff. This enhanced exposure leaves no doubt that the outcrops belong to two, immediately successive, members of the Kinnesswood Formation -- the lower the Doughend Sandstone, the upper the Foul Port Mudstone – and that they provide some of the best available exposures on which to base description and interpretation. The facies of the fluviatile Doughend Sandstone shares many characteristics with the underlying Kelly Burn Sandstone of the Upper Old Red Sandstone, whereas that of the Foul Port Mudstone is distinct and unusual, attributed to local tectonics, influenced by movements on older and more major fractures such as the Highland Boundary Fault, with sediment accumulation taking place in a playa-lake complex of considerable extent.
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19,273 members
Richard Renneboog
  • Department of Chemistry
Ian Colquhoun
  • Department of Anthropology
John A Kiernan
  • Department of Anatomy and Cell Biology
Tom Overend
  • School of Physical Therapy
1151 Richmond Street, N6A 3K7, London, Ontario, Canada
Head of institution
Alan Shepard
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