University of Lethbridge
OPUS: Open Uleth Scholarship - University of Lethbridge Research RepositoryNot a member yet
4423 research outputs found
Sort by
Benchmarking tree species classification from proximally sensed laser scanning data: introducing the FOR-species20K dataset
No full textOpen access article. Creative Commons Attribution-NonCommercial 4.0 International license (CC BY-NC 4.0) applies1. Proximally sensed laser scanning presents new opportunities for automated forest ecosystem data capture. However, a gap remains in deriving ecologically pertinent information, such as tree species, without additional ground data. Artificial intelligence approaches, particularly deep learning (DL), have shown promise towards automation. Progress has been limited by the lack of large, diverse, and, most importantly, openly available labelled single-tree point cloud datasets. This has hindered both (1) the robustness of the DL models across varying data types (platforms and sensors) and (2) the ability to effectively track progress, thereby slowing the convergence towards best practice for species classification.
2. To address the above limitations, we compiled the FOR-species20K benchmark dataset, consisting of individual tree point clouds captured using proximally sensed laser scanning data from terrestrial (TLS), mobile (MLS) and drone laser scanning (ULS). Compiled collaboratively, the dataset includes data collected in forests mainly across Europe, covering Mediterranean, temperate and boreal biogeographic regions. It includes scattered tree data from other continents, totaling over 20,000 trees of 33 species and covering a wide range of tree sizes and forms. Alongside the release of FOR-species20K, we benchmarked seven leading DL models for individual tree species classification, including both point cloud (PointNet++, MinkNet, MLP-Mixer, DGCNNs) and multi-view 2D-based methods (SimpleView, DetailView, YOLOv5).
3. 2D Image-based models had, on average, higher overall accuracy (0.77) than 3D point cloud-based models (0.72). Notably, the performance was consistently >0.8 across scanning platforms and sensors, offering versatility in deployment. The top-scoring model, DetailView, demonstrated robustness to training data imbalances and effectively generalized across tree sizes.
4. The FOR-species20K dataset represents an important asset for developing and benchmarking DL models for individual tree species classification using proximally sensed laser scanning data. As such, it serves as a crucial foundation for future efforts to classify accurately and map tree species at various scales using laser scanning technology, as it provides the complete code base, dataset, and an initial baseline representative of the current state-of-the-art of point cloud tree species classification methods.Ye
Juvenile male rats form preferences based on strain when playing in groups but not in pairs
No full textOpen access article. Creative Commons Attribution 4.0 International (CC BY 4.0) appliesLike many young mammals, juvenile rats engage in rough-and-tumble play. Play occurs naturally both in wild and laboratory rats, making it a suitable, ethologically relevant behavior to investigate. In the laboratory, rats are typically housed and tested in dyads, despite living in large colonies in the wild. Consequently, when tested in the lab, rats do not have a choice of partners and are instead paired with whomever the researcher selects. Given that both the amount and style of play rats engage in varies considerably depending on the strain of rat being studied, we tested whether rats select play partners based on strain. To do so, juvenile male Long Evans (LE) focal rats (n = 8) were subjected to three play contexts: (1) group play; (2) dyadic play; and (3) social conditioned place preference. During group play, the LE subject rats were given the choice to play with an LE, a Sprague Dawley (SD), or Fischer 344 rat (F344), simultaneously. During dyadic play, focal rats played one-on-one with an LE, SD, or F344 partner. Finally, the rats were conditioned to a context and a social stimulus, with the context either being paired with an LE (preferred stimulus) or F344 (unpreferred stimulus) partner. We found that, when given a choice in a group setting, LE focal rats prefer to play with same-strain partners over both SD and F344 partners. However, when playing under dyadic conditions (i.e., with an assigned partner), LE rats played with each strain equally. Finally, in the socially conditioned place preference test, we found that the focal rats formed preferences for a particular enclosure, but not for the strain. Together, these results suggest that when given a choice, LE rats prefer to play with their own strain, but when they do not have a choice, any strain will do. Given that the testing paradigm can greatly influence the results obtained and the conclusions drawn, our findings highlight the need to consider the research question(s) being asked when determining the most appropriate paradigms to employ.Ye
Review of the book Wish you were here: guidebooks, viewbooks, photobooks and maps of New York City, 1807-1940, from the collection of Mark D. Tomasko
No full textOpen access article. Creative Commons Attribution-NonCommercial 4.0 International license (CC BY-NC 4.0) appliesBook reviewYe
Computational investigations into interactions between metal ions and nucleic acids
No full textMetal ion contamination is an ongoing global crisis that negatively affects human and environmental health. As a result, metal ion detection and remediation techniques are required. Nucleic acids are promising tools as biosensors for metal detection. Although nucleic acid sensors have been designed for some metal ions (e.g., Cs+, Pb2+), there are metal ion contaminants that require sensing and remediation for which no sensors currently exist. Specifically, with increasing mining and usage of lithium in lithium-ion batteries, rising levels of lithium ions are present in the environment. To design nucleic acid sensing and remediation platforms, it is important to understand how metal ions interact with nucleic acids. Computer modeling can provide valuable insights into structural and binding information of metal–nucleic-acid interactions, thereby aiding the rational design of nucleic-acid-based sensing and remediation solutions for metal ions. This thesis uses different computational techniques, including ab initio (CCSD(T)/CBS), density functional theory (DFT), molecular dynamics (MD), and ab initio molecular dynamics (AIMD) to identify reliable methods to describe metal–nucleic-acid interactions, understand how metal ions interact with nucleic acids, and explore modifications that can capture lithium. The information gained from this thesis lays the groundwork for designing a lithium-specific nucleic acid platform for lithium extraction, which can also support future development of a nucleic acid sensor for lithium. Additionally, insights gained can be applied to designing sensing and extraction platforms for other metal ions, and aid development of therapeutics and materials
Over or under: new phylogenetic insights in the evolution of head scratching in birds
No full textOpen access article. Creative Commons Attribution 4.0 International license (CC BY 4.0) appliesSome birds scratch their heads by moving their foot ventrally underneath their wing and others do so by moving their foot over their wing. Two competing hypotheses have been proposed to explain the distribution of these patterns. The phylogenetic hypothesis proposes that the underwing route is a novel pattern evolved in birds as the evolution of wings meant that the foot did not have to move over the front leg as is it does in quadrupeds. Consequently, the overwing route is an atavism reflecting the tetrapod ancestry of birds. The biomechanical hypothesis proposes that body morphology or environmental context determines which pattern is most effective and so explains variation across species. Earlier attempts to test these hypotheses were limited by relatively small, taxonomically biased samples of birds that did not take phylogenetic relationships into account and with few morphological traits explicitly compared. The present study includes data for 1157 species from 92% of avian families and expands the number of morphological traits compared. The most plausible ancestral state, at least for Neoaves, was overwing scratching, turning the original phylogenetic hypothesis on its head. It is also clear from the analyses that head scratching pattern is a highly labile evolutionary trait that, in some orders, repeatedly switches between over and under wing patterns. Moreover, while some morphological traits biased the likely scratching pattern used in some clades, the biomechanical hypothesis failed to predict the pattern of scratching across all birds. The most likely explanation is that the two forms of scratching are independently evolved behavior patterns and that a yet to be determined reason can switch between patterns in different lineages.Ye
Towards new zwitterioinic difluoroglycine analogues: preparation methods and reactivity studies
No full textResearch into new methods of fluorination is imperative as the addition of fluorine onto organic molecules has a great influence on a compound’s properties. Difluorocarbene can be used in such fluorination methods, and it is currently being explored for its unique properties. The purpose of this thesis was to see if it was possible to create new zwitterionic difluoroglycine-derived difluorocarbene precursors, and to test their ability against the previously reported phosphine-based analogue. The formation of the phosphine-based difluorocarbene source is achieved through nucleophilic substitution, and then release of the difluorocarbene through heating. It was believed that this procedure can be ameliorated, by improving the atom economy of the reaction, as well lowering the temperature of release allowing for better use on small scale and in industry. First, the precursors would have the phosphine group swapped for new nitrogen and sulfur-based groups, hopefully allowing for difluorocarbene release at a lower temperature. This was tested by using different types of amines, pyridines and two sulfides. A subset of potential difluorocarbene precursors was thus synthesized. The new difluorocarbene sources were tested in (2+1) cycloaddition reactions and difluoromethylation reactions to test their ability to release the difluorocarbene. The nitrogen-based precursors were tested against the phosphine analogue and showed comparable results. However, all data collected proved that the concept of forming these new difluoroglycine analogues and their reactivity bears potential, but is not fully understood yet. The work presented in this thesis gives key insights into the possibility of synthesizing zwitterionic difluoroglycine analogues and their subsequent reactivity
Biophysical characterization of Zika virus terminal region interactions
No full textRecent viral threats have intensified research into viral mechanisms and the various interactions during their viral life cycle. Viruses such as Zika virus have continued to threaten healthcare systems around the globe, with large outbreaks affecting over 3 million people within the last decade. While viral proteins have received significant attention, the untranslated terminal regions (TRs) flanking the single-stranded RNA genome play crucial roles in the viral life cycle. These TRs facilitate replication through interactions with host/viral proteins and through self-association via cyclization, which regulates transcription and translation. This thesis characterizes the biophysical and cellular properties of this cyclization interaction and the TRs interaction with the host protein FXR1. Using size exclusion multi-angle light scattering and analytical ultracentrifugation, we defined the hydrodynamic profiles of the TRs and FXR1. Microscale thermophoresis quantified the affinity and specificity of the TRs cyclization interaction, as well as the affinity of FXR1 for the TRs. Cellular studies further demonstrated that TR mutations disrupting cyclization drastically reduce viral replication. Collectively, this work identifies a sequence specific interaction governing Zika virus replication and establishes a foundation for characterizing the TR-FXR1 interaction, offering potential targets for future therapeutic development
Predictors of detoxification services use in Alberta: a provincial socio-demographic and utilization analysis
No full textDetoxification is the first step in the substance use and addictive behaviours recovery process, serving as the transition between dependency and reduced use or abstinence. Completing detoxification is an important milestone in initiating recovery and remission of withdrawal symptoms, as well as facilitating follow-up treatment. However, high non-completion rates, low transition to residential treatment, and frequent use of detoxification services pose significant challenges to substance use disorder and behavioural addiction treatment and detox programs. This is the first study of the predictors in detoxification programs in Alberta, marking a significant step in understanding the predictors of completion and non-completion rates of detoxification, transfer to residential treatment, and repeated use of detox services based on data from five residential withdrawal management services in Alberta, Canada. The thesis consists of three manuscripts: (1) The first manuscript identifies the factors that predict detoxification service use, estimates program completion and non-completion rates, and the proportion of clients who cycle between completion and non-completion; (2) The second manuscript estimates clients' transition rates from detoxification to residential treatment services and identifies predictors of such transitions; (3) The third manuscript estimates the prevalence of repeated use of residential withdrawal management services in Alberta, Canada and identifies predictors of frequent use
The Hip-Hop and Mental Health Handbook for Mental Health Practitioners
No full textHip-hop culture is a dynamic, multifaceted movement with profound relevance to mental health practices, albeit one that few professionals have experience with. Practitioners can develop more creative, culturally responsive, and trauma-informed approaches by understanding hip-hop culture and realizing how it can be used to improve mental health. This project articulates a literature review of several critical areas including a brief history of hip-hop culture, hip-hop through a Canadian lens, and the application of hip-hop in mental health practices. Additionally, this project includes a handbook that translates findings from the literature review into an accessible, interdisciplinary resource for professionals seeking to better understand hip-hop culture and potentially incorporate it into their practice. By increasing visibility and facilitating a better understanding of the relationship between hip-hop culture and mental health, this project aims to improve professionals’ engagement with hip-hop as a therapeutic tool in working with diverse, relevant populations
Entertainment or propaganda? : cultural cognition: implicit stereotypes in historical film
No full textThis thesis explores the intersection of culture and cognition, presenting an investigation into how implicit bias may be propagated through representations of antiquity in Hollywood historical film. These biases often align with the binary framework of Orientalism, critiqued by Edward Said, which positions Middle Eastern geopolitical entities and peoples as one monolithic “Oriental Other”. Historical films portray this stereotypically exotic, oppressive, and backward “Orient” as an archetypal component of the ancient world, defined by its enmity with the “West”. By contributing to the cultural narrative presenting a historical divide between a monolithic “Eastern” and “Western” world, cinematic depictions of antiquity may further propagate implicit stereotypes concerning the Eastern “other”. This process may in turn influence the perception, and practise, of contemporary international relations. In order to elucidate the mechanisms of implicit bias propagation, cognitive psychological frameworks were applied to this analysis. Tversky and Kahneman’s cognitive heuristics of “availability” and “representativeness” were contextualized within Perry Hinton’s argument of implicit bias arising, not from individual cognition, but rather from prevalent stereotypical associations within culture, i.e., the “culture in mind”. This multidisciplinary paradigm was used to analyze specific stereotypical tropes fitting the Orientalist framework within thirty-five, predominantly Hollywood, historical films. These tropes encompassed geopolitics, race, appearance, visual setting, disability, gender, and sexuality. The discussion suggested that historical films indeed present an implicit argument, associating the ancient Middle East with a homogenous and stereotypical contemporary “East”, one fundamentally opposed to “Western” liberty and morality. Examples such as the release of Zack Snyder’s 300 during the Iraq War were examined, demonstrating how cinematic representations of antiquity may propagate an implicit perspective that the “clash of civilizations” between “East” and “West” is timeless, rather than a hyperreal Orientalist construct