30921 research outputs found
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Investigating the metabolic landscape of recurrent group 3 medulloblastoma
No full textMedulloblastoma (MB) is the most common malignant brain tumor in children, accounting for approximately 25% of all pediatric brain tumors. Among medulloblastoma, group 3 medulloblastoma (MBG3) carries the poorest prognosis, with a 5-year overall survival of less than 60%. The current standard of care consists of maximal surgical resection followed by radiation therapy and adjuvant chemotherapy. However, despite this aggressive treatment approach, approximately 30% of MBG3 patients experience tumor relapse. These recurrent tumors are often metastatic and resistant to therapy, underscoring the critical need to understand the mechanisms underlying therapy resistance in MBG3 cells. To investigate this, we examined cellular metabolic adaptations in response to the stress induced by chemoradiotherapy (CRT). Our findings revealed a distinct upregulation of mitochondrial tricarboxylic acid (TCA) cycle enzymes in MBG3 cells following CRT exposure. However, this increase was not accompanied by a corresponding rise in mitochondrial activity. Instead, we observed that these enzymes were selectively upregulated within the nuclear compartment of CRT-treated (CRT-T) cells. The presence of TCA cycle activity in the nucleus suggests a potential role for metabolite-driven epigenetic modifications in response to CRT. To explore this, we examined key histone modification sites commonly altered in MBG3: histone H3 lysine 27 (H3K27), histone H3 lysine 9 (H3K9), and histone H3 lysine 4 (H3K4). Our analysis confirmed significant changes in both acetylation and methylation, indicating that CRT promotes a transcriptionally active state that may enable MBG3 cells to adapt by upregulating genes associated with stress response and survival. Moving forward, identifying these transcriptional changes will provide critical insights into the mechanisms driving tumor relapse in MBG3, potentially uncovering novel therapeutic targets to overcome treatment resistance.October 202
In search of Net Positive Carbon Grain Farming in the Northern Great Plains: innovation in policy and practice
Full text linkThis thesis addresses the opportunities that exist for grain farms to help mitigate anthropogenic global warming. The thesis developed Rourke’s General Farm Practice Change Theory, then uses that theory to develop a Net Positive Carbon Grain Farming Framework along with a Global Warming Mitigation Credit Framework. In-depth semi-structured interviews were conducted for sixteen cases involving participants from Manitoba, Saskatchewan, Alberta, North Dakota, and South Dakota. The research is a qualitative exploratory participatory narrative case study. The data was transcribed via UM Zoom and uploaded to NVivo where it was coded and queried for emerging themes. Data was also collected to calculate estimates of emissions, CO2 sequestration, contribution margins, and production output. From this data I was able to determine a Net Positive carbon grain farming score as well as a Sustainable Farm Index rating.
During the interview, each participant was asked 10 questions on each of 12 Beneficial Management Practices, BMPs. A 1 to 5 scale was used to record their response and then fed into a tool developed for the study labelled as BERT /E. The BERT/E tool considers the following variables: beliefs (B), economics (E), regulatory (R), technology (T), and the farmer’s physical and mental energy (E) to make a change. BERT/E scores are an indicator of the farmers BMP adoption score.
This study yielded both theoretical advancement as well as practical outcomes. The practical outcomes included identifying two participants whose farms are currently Net Positive. This included identifying the BMPs they used to become Net Positive and how their approach differed from the overall group. I was also able to assemble 50 recommendations that would improve the ability of the twelve BMPs to assist farmers in becoming Net Positive. Ultimately, the findings of this work demonstrate that grain farms can be instrumental in tackling anthropogenic global warming.October 202
Rolling Bearing Early Fault Detection Method Based on Feature Clustering Fusion Degradation Index
No full textAbstract The research on rolling bearing early fault detection is mainly focused on degradation index extraction and adaptive setting of alarm threshold. The mainstream methods are to extract degradation indicators based on adaptive features and set adaptive alarm thresholds based on the Shewhart control chart. However, the adaptive feature extraction method does not consider the correlation between features, and the Shewhart control chart is not sensitive to small fluctuations caused by early faults. In this study, a rolling bearing early fault detection method based on a feature clustering fusion degradation index is proposed. The multidomain statistical features are extracted to form the initial feature set, and the improved hierarchical clustering algorithm is combined with the feature evaluation index to select features to form a preferred feature subset, to ensure the richness of index information and reduce redundancy. After the construction of the degradation index, to suppress the interference caused by nonstationary and abnormal shocks in early fault detection, the accurate evaluation method and anomaly determination strategy of control chart parameters are studied, and an improved exponential weighted move average control chart is designed to monitor the degradation index. The effectiveness and superiority of the proposed method are verified by public data sets. This research provides a rolling bearing early fault detection method, which can provide comprehensive degradation indicators, eliminate interference caused by random anomalies and running in periods, and achieve an accurate detection of early bearing failures
Peace spoilers in different stages of the peacebuilding process in the Chattogram Hill Tracts (CHT) in Bangladesh
No full textThis thesis examines the dynamics of peace spoilers in the Chattogram Hill Tracts (CHT) conflict in Bangladesh, analyzing their emergence, motivations, tactics, and impacts across the pre-accord (1972–1995), negotiation (1996–1997), and post-accord (1997–present) phases of the peacebuilding process. This study employes a secondary data analysis methodology and synthesizes historical documents, and incident-level media reports from national and the local CHT area from January 2020–July 2025 to provide an explorative understanding of spoiler behavior and their impact. Drawing on peacebuilding theories (Galtung, 1969; Lederach, 1997) and spoiler typologies (Stedman, 1997; Zahar, 2006), the research identifies key spoilers, including the Parbatya Chattagram Jana Samhati Samiti (PCJSS), the Kuki-Chin National Front (KNF), the United People’s Democratic Front (UPDF), the Bangladeshi government, and Bengali settlers, among others, whose actions were driven by structural marginalization, exclusion, and unmet grievances. This potentially has undermined the 1997 CHT Peace Accord. Findings reveal that incomplete implementation, particularly on land rights and demilitarization, has perpetuated violence, with Indigenous civilians disproportionately affected (85 per cent of victims in 54 recorded incidents). Bandarban has faced most violent impact (56 per cent) among three districts. This analysis also identified that all the actors had animosity among themselves even though they share similar goals (such as, to protect Indigenous rights). The study highlights the interplay of structural, relational, and political factors in sustaining dynamic spoiling behavior, emphasizing the need for inclusive dialogue, sequenced incentives, and trauma healing to foster sustainable peace. This study identifies a peacebuilding phase-specific framework for understanding spoilers and practical strategies for peacebuilding in complex ethnic conflicts. This study also reveals a shift in actor dynamics in the CHT, including new emerged actors in recent times.February 202
Platinum(II) Complexes of Benzannulated N^N–^O-Amido Ligands: Bright Orange Phosphors With Long-Lived Excited States
No full textThe synthesis, structural characterization and photophysical properties of a series of platinum(II) complexes of benzannulated pincer-type diarylamido ligands are described. The ligands all contain tricyclic phenanthridine (3,4-benzoquinoline) rings as donor arms, which were elaborated into N^N–^O-coordinating β-enaminoketonato chelates via partial condensation with acetylacetone. The proligands are easily deprotonated, and metallation can be achieved under mild conditions using simple Pt(II) salts and Ag2O as a base. The resulting Pt(II) complexes exhibit strong metal-to-ligand charge-transfer absorptions in the region of ~450-575 nm and are phosphorescent in solution at room temperature, emitting bright orange light (λmax ~ 600 nm) with quantum yields of up to 16% and excited-state lifetimes on the order of ~20 μs, representing significant improvements to these photophysical properties compared with previously reported N^N^O or N^N^N-ligated systems. Computational modelling reveals that the lowest-lying triplet state is populated efficiently due to strong coupling between singlet and triplet excited state manifolds, as in cyclometallated compounds of Pt(II). Substituents (CH3, tBu, or CF3) in the 2-position of the phenanthridinyl unit are found to have little influence on the optical properties, but the emission is severely quenched when a methyl substituent is introduced ortho to the coordinating nitrogen. Molecular distortions in the excited state are shown to be primarily responsible for the quenching in this complex
Identifying important habitat of forage fish and their seabird predators in coastal Newfoundland, Canada
No full textThe ecological niche is the set of environmental characteristics required for a species to grow, survive, and reproduce. Although individuals are predicted to select habitat within a range of conditions that maximize fitness throughout their annual cycle, information regarding the availability of suitable habitat or species-specific differences in habitat use are often limited. Here, I identified important habitat for forage fish, critical energy links between lower and upper trophic levels of marine food webs, and their seabird predators in coastal Newfoundland, Canada. I developed habitat suitability models for three forage fish species/groups to predict the location and extent of suitable coastal habitat for each species in two bays during spawning (Atlantic herring Clupea harengus, spring; capelin Mallotus villosus, summer) or year-round (sand lance Ammodytes spp.; Chap. 2). Suitable habitat was more limited for all species during summer (Notre Dame Bay; 8.1–73.3% of surveyed area) relative to spring (Fortune Bay; 25.2–100%) and sand lance burying habitat was more limited and patchier (8.1–25.2%) in both bays relative to capelin (35–97.6%) and herring (73.3–100%), suggesting sand lance are most vulnerable to habitat loss. 2.1°C ocean warming resulted in predicted decreases in the extent of suitable habitat for all species during summer. I also examined the foraging habitat of three breeding seabird species in coastal Newfoundland by quantifying species-specific prey patch characteristics in foraging hotspots (derived from archived GPS tracking datasets) during at-sea surveys (Chap. 3). Foraging hotspots for each species differed based on community and environmental variables. Atlantic puffins Fratercula arctica foraged at deeper, colder sites with lower prey densities compared to razorbills Alca torda, suggesting puffin displacement from high-quality prey patches. Common murres Uria aalge foraged at higher conspecific densities and at a broader range of prey densities and depths relative to puffins and razorbills. Together, these findings revealed persistent seabird foraging areas where forage fish complete important parts of their annual cycle (e.g., spawning), identified limited suitable habitat for forage fish, and elucidated divergent foraging habitat characteristics among breeding seabird species, informing conservation and management decisions (e.g., spatial planning) for important species in coastal Newfoundland, Canada.Additional funding provided by Natural Sciences and Engineering Research Council of Canada (NSERC) Discovery Grant, NSERC Ship Time Grant, Fisheries and Oceans Canada Environmental Baseline Program, Manitoba Métis Federation Post-Secondary Education Support Program, University of Manitoba Faculty of Science and Department of Biological SciencesOctober 202
Promoting family functioning through physical activity: a randomized trial to evaluate the “All in the Family” program
No full textBackground: Effective family functioning, such as communication, family organization, and family cohesion, is essential for family well-being and child development. Promoting family physical activity (PA) through shared activities offers a promising strategy for enhancing family dynamics. Developing a strong parenting PA identity (e.g., seeing oneself as a parent who supports their child’s PA) and a family social identity around PA (e.g., perceiving the family as an active unit) may further strengthen motivation and commitment to engaging in PA. This study aims to evaluate the efficacy of three family PA interventions: (1) PA education alone; (2) PA education + PA parenting self-regulation skills; and (3) PA education + PA parenting self-regulation skills + PA parenting identity. The primary outcome is family cohesion, a key dimension of family functioning. Secondary objectives include examining the effects of these interventions on (1) family-functioning dimensions of flexibility and organization, (2) child PA levels and parent–child co-participation in PA, (3) parental PA support and its potential antecedents (i.e., parental support constructs derived from the Multi-Process Action Control Framework, and parent-perceived family PA social identity), and (4) exploring potential moderating effects of seasonal variation, child and parent characteristics, intervention adherence, and PA type.
Methods: The three-armed, single-blind randomized controlled trial compares the efficacy of the three interventions over a 6-month period. Families are eligible if they have a child between the ages of 6 and 12 who is not meeting the Canadian 24-Hour Movement Guidelines for Children and Youth. Participants are randomly assigned to one of the three intervention groups. Family functioning, child PA and parent–child co-participation in PA, parental PA support, family PA social identity, and related constructs (e.g., perceived capability and opportunity, behavioral regulation, and habit) are assessed at baseline, 6 weeks, 3 months, and 6 months post-intervention. Recruitment methods include social media, recruitment poster drops, and community-based promotion.
Trial registration: ClinicalTrials.gov NCT06098716. Registered on October of 2023, updated on August 2024
Designing Biphenanthridine-Based Singlet Fission Materials Using Computational Chemistry
No full textSinglet fission has the potential to significantly improve the efficiency of photovoltaic devices by harnessing high-energy sunlight to double the photocurrent that can be generated in standard semiconductors. The challenge is identifying materials capable of undergoing this process efficiently. Herein, we present the results of a systematic search for novel intermolecular singlet fission materials based on the recently synthesized 6,6'-biphenanthridine (biphe) framework utilizing a straightforward computational approach. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) were employed to study the photophysics of various structural analogues of biphe. These analogues were generated in silico by utilizing an extensive range of transformations, including planarization, protonation, symmetric and asymmetric alkylation, electron-donating and electron-withdrawing group substitution, N-oxide substitution, and symmetric and asymmetric π-extension and contraction. Analysis of the effects of these structural modifications on the energies of the lowest singlet and triplet excited states revealed that (2,2',10,10'-tetra-N-oxide) planar biphe has an E(S1)/E(T1) ratio of 2.12 and an E(T2)/E(T1) of 2.05, suggesting its potential for intermolecular singlet fission. Additionally, N-methylated biphe emerged as a promising contender for thermally activated delayed fluorescence. The effects of solvation are also discussed
Enhanced physics modelling and multistatic data integration for breast tissue reconstruction in microwave radar imaging
No full textMicrowave breast imaging offers a low-cost, portable, and non-ionizing alternative for breast cancer detection by exploiting the contrast in dielectric properties between malignant and healthy tissues. Its simplicity and safety make it particularly attractive for screening in under-served or remote communities where conventional imaging modalities may be unavailable. However, three core challenges have limited its diagnostic performance: (1) standard Delay-and-Sum (DAS) beamformers assume a homogeneous medium and ignore tissue heterogeneity; (2) they neglect the frequency dependence of dielectric properties; and (3) true propagation speeds in complex breast tissues are unknown and must be estimated. Moreover, existing image-quality assessments rely on single-pixel contrast and localization metrics, offering little guidance for algorithmic refinement. This thesis addresses these gaps through three methodologies. Firstly, an enhanced-physics beamforming algorithm was developed as a combination of an analytical binary-partitioning model with a full frequency-dependent propagation-speed formulation, yielding piecewise time delays. The enhanced physics modelling was observed to improve image quality. Secondly, a robust, sinogram-based boundary detection algorithm was proposed to extract realistic breast outlines from raw data from the Vector Network Analyzer (VNA), replacing idealized circular models and allowing for a boundary-aware beamforming and skin suppression for the differential imaging. Thirdly, a phase-based technique of experimental propagation speed extraction was developed using the multistatic microwave data.October 202
Impact of lutein and docosahexaenoic acid-enriched eggs on retina and metabolic health in type 2 diabetes
No full textVision impairment resulting from diabetic retinopathy is a growing concern among individuals with type 2 diabetes mellitus (T2DM). However, early retinal dysfunction can occur even in the absence of clinically detectable diabetic retinopathy. Lutein and docosahexaenoic acid (DHA) are key nutrients to support retina and macular health. Consumption of eggs enriched with lutein and DHA has been shown to positively influence retinal function in healthy older Caucasian adults. This research was planned to examine: i) retinal function and macular pigment levels in individuals with T2DM without diabetic retinopathy ii) discrepancies between self-perceived vision status and objective retinal assessments, and iii) the impact of lutein- and DHA-enriched egg consumption on retinal and metabolic health in T2DM. A total of 64 adults (34 T2DM; 30 with normal glucose metabolism, NGM) participated in a cross-sectional study, followed by a 6-week intervention trial involving daily consumption of enriched eggs (0.87 mg lutein, 220 mg DHA). Assessments included electroretinogram (ERG), macular pigment optical density (MPOD), skin carotenoid levels, plasma DHA, glucose and lipid profiles, dietary intake, and vascular and body composition parameters. Individuals with T2DM demonstrated significantly slower ERG responses (p<0.01) and lower skin carotenoid scores (p<0.05) compared to NGM, despite reporting no perceived vision impairment. Egg intervention increased plasma DHA levels (p<0.05) without altering MPOD or ERG responses over 6 weeks. Retinal dysfunction in T2DM may be underrecognized due to discrepancies between perceived and actual vision status. While short-term consumption of lutein- and DHA-enriched eggs improved DHA status without adverse effects, longer interventions may be necessary to influence retinal outcomes in T2DM.October 202