Queens University of Charlotte

In this paper we revisit the digital signature scheme proposed by Kahrobaei and Koupparis using non-commutative groups. We implement this scheme and analyze some infinite polycyclic groups as platform groups.

Background Weather-related stressors on healthy brain development has become an important topic in recent years. Notably, prenatal stress exposure to natural disasters may disrupt child neurodevelopment, with recent research exploring its impact on child brain morphology. Prenatal exposure to extreme weather events, such as ambient heat, may also affect child brain morphology. The basal ganglia, while historically related to motor ability, has gained increasing attention for its role in various non-motor functions, such as emotion regulation. Leveraging an existing cohort with and without prenatal exposure to Superstorm Sandy (SS), a category 3 hurricane at its peak, this study aims to investigate how prenatal exposure to both a natural disaster and extreme ambient heat impacts this important subcortical region. Methods Main effects of SS and extreme heat exposure on basal ganglia volume were first analyzed to examine the independent effect on brain outcomes. Moderation models subsequently explored the potential role extreme heat had on the association between SS and basal ganglia volume. We used magnetic resonance imaging to measure basal ganglia gray matter volume at age 8 among 11 SS-exposed and 23 non-exposed children. Results The SS-exposed group, relative to their non-exposed counterparts, had significantly larger volume in the putamen and pallidum bilaterally, and right caudate. No notable main effects of extreme heat were found. Moderation models revealed, however, extreme heat exposure amplified the adverse impact of SS exposure on basal ganglia volume, evidenced by reduced left nucleus accumbens and increased left pallidum volume. Conclusions Prenatal exposure to SS impacted child brain development. Extreme heat amplified this risk via increased and reduced brain volume from different basal ganglia subregions. Alongside promoting initiatives to combat climate change, increasing awareness of the potential dangers of exposure to extreme climate events for pregnant individuals is vital for protecting long-term child brain development.

Background This study investigated the presence of the healthy vaccinee effect—the imbalance in health status between vaccinated and unvaccinated individuals—in two rigorously conducted COVID-19 vaccine effectiveness studies involving primary series and booster vaccinations. It also examined the temporal patterns and variability of this effect across different subpopulations by analyzing the association between COVID-19 vaccination and non-COVID-19 mortality in Qatar. Methods Two matched, retrospective cohort studies assessed the incidence of non-COVID-19 death in national cohorts of individuals with a primary series vaccination versus no vaccination (two-dose analysis), and individuals with three-dose (booster) vaccination versus primary series vaccination (three-dose analysis), from January 5, 2021, to April 9, 2024. Results The adjusted hazard ratio (aHR) for non-COVID-19 death was 0.76 (95% CI: 0.64–0.90) in the two-dose analysis and 0.85 (95% CI: 0.67–1.07) in the three-dose analysis. In the first 6 months of follow-up in the two-dose analysis, the aHR was 0.35 (95% CI: 0.27–0.46); however, the combined analysis of all subsequent periods showed an aHR of 1.52 (95% CI: 1.19–1.94). In the first 6 months of follow-up in the three-dose analysis, the aHR was 0.31 (95% CI: 0.20–0.50); however, the combined analysis of all subsequent periods showed an aHR of 1.37 (95% CI: 1.02–1.85). The overall effectiveness of the primary series and third-dose vaccinations against severe, critical, or fatal COVID-19 was 95.9% (95% CI: 94.0–97.1) and 34.1% (95% CI: –46.4–76.7), respectively. Subgroup analyses showed that the healthy vaccinee effect is pronounced among those aged 50 years and older and among those more clinically vulnerable to severe COVID-19. Conclusions A pronounced healthy vaccinee effect was observed during the first 6 months following vaccination, despite meticulous cohort matching. This effect may have stemmed from a lower likelihood of vaccination among seriously ill, end-of-life individuals, and less mobile elderly populations. Funding Biomedical Research Program and the Biostatistics, Epidemiology, and Biomathematics Research Core, and Junior Faculty Transition to Independence Program, all at Weill Cornell Medicine-Qatar, Qatar University, Ministry of Public Health, Hamad Medical Corporation, Sidra Medicine, Qatar Genome Programme, Qatar University Biomedical Research Center, and L’Oréal-UNESCO For Women In Science Middle East Regional Young Talents Program.

Brain activity emerges in a dynamic landscape of regional increases and decreases that span the cortex. Increases in activity during a cognitive task are often assumed to reflect the processing of task-relevant information, while reductions can be interpreted as suppression of irrelevant activity to facilitate task goals. Here, we explore the relationship between task-induced increases and decreases in activity from a geometric perspective. Using a technique known as kriging, developed in earth sciences, we examined whether the spatial organisation of brain regions showing positive activity could be predicted based on the spatial layout of regions showing activity decreases (and vice versa). Consistent with this hypothesis we established the spatial distribution of regions showing reductions in activity could predict (i) regions showing task-relevant increases in activity in both groups of humans and single individuals; (ii) patterns of neural activity captured by calcium imaging in mice; and, (iii) showed a high degree of generalisability across task contexts. Our analysis, therefore, establishes that antagonistic relationships between brain regions are topographically determined, a spatial analog for the well documented anti-correlation between brain systems over time.

Community hospitals represent 90% of Canadian hospitals, yet many lack the necessary infrastructure to conduct health research. This shortfall limits patient access to research studies, reduces study efficiency, and decreases the generalizability of study results. Previous work from our group identified an increase in publications from Ontario’s large community hospitals between 2013 and 2022. However, data from other Canadian provinces is lacking. This bibliometric analysis identified indexed publications from authors affiliated with Canada’s 544 community hospitals between 2018 and 2023. Among 13,689 publications, 12,472 unique articles were identified. Most were primary research articles (67%), with only 5% being clinical trials. Ontario’s community hospitals had the highest number of publications (n = 7,925), followed by Alberta (n = 2,086) and Quebec (n = 1,480). Of Canada’s 544 community hospitals, only 42% were affiliated with one or more publications from 2018 to 2023, highlighting the need to strengthen Canadian community hospital research capacity at a systems level.

Childhood anxiety imposes substantial economic burdens on families, schools, and medical services. Interventions to reduce anxiety may be economically valuable, particularly if they can be delivered at low cost. This study examined the cost-effectiveness of two school nurse-delivered anxiety interventions for elementary school children: CALM (Child Anxiety Learning Modules, cognitive behavioral skills) and CALM-R (relaxation skills). In this pilot randomized controlled trial (RCT) 30 school nurses delivered CALM or CALM-R to 54 children with elevated anxiety. CALM and CALM-R demonstrated intervention affordability, with nurse training and nurse delivery costs at $560 and$630 respectively per child. At baseline, we found significant economic resources used by school systems, families, and health systems to support students with anxiety ($3,660-$5,350 per child). At three-month follow-up, total resource use– including intervention costs and all other services -- was lower for children in CALM but higher for CALM-R. For CALM, the implementation cost was more than offset by subsequent resource savings. Moreover, at three month follow up, responder status per child was higher for CALM (60%) than for CALM-R (35%). Thus, CALM students required fewer resources and experienced greater clinical benefits than students in CALM-R. Incremental Cost-Effectiveness Analysis showed that CALM was more cost-effective than CALM-R: the cost per incremental responder student was $6,291 lower. CALM has a high probability of acceptance across all positive values of willingness to pay for anxiety reduction. Evidence from this study indicates that cognitive behavioral skills delivered by school nurses may offer a cost-effective response to childhood anxiety.

Introduction No prediction models exist for the success for buprenorphine initiation in opioid-naïve patients or in transition from other opioids in patients treated for chronic pain. Objectives To create a prediction model for the successful use of buprenorphine to treat chronic pain. Methods Stepwise Akaike information criterion prediction modeling procedures were applied to a harmonized participant-level data set of 10 enriched enrollment randomized withdrawal clinical trials of buprenorphine submitted to the Food and Drug Administration. Available baseline factors and nine patient-reported outcomes were considered to predict success with the titration (10 studies) and maintenance of benefit after randomization (5 studies). Patient-reported outcomes were modeled separately given inconsistent use across studies. Results No prediction model reached an area under the receiver operator curve ≥0.70, the threshold for clinical usefulness. Successful initiation or transition of buprenorphine was accomplished in 3541 of 6052 (58.7%) participants, and 614 of 877 (70.0%) completed the 12-week maintenance phase with no difference between opioid-experienced and opioid-naïve participants. Only a medical history of obesity and baseline pain were retained in the overall titration model and only baseline pain in the maintenance model. Only brief pain inventory and subject opioid withdrawal scores were retained in the titration subsets containing those measures. Conclusion No clinically useful prediction models of clinical benefit were identified, but a few covariates may be of interest in future studies of the initiation of buprenorphine in opioid-naïve patients or of transition from other opioids to buprenorphine. The lack of a predictor supports considering a trial of buprenorphine in clinically relevant scenarios for patients without known opioid use disorder, including careful monitoring and an a priori plan to deal with any problems that may occur.

Tertiary amines in water exhibit CO2-responsiveness through the equilibrium between the neutral form and the tertiary ammonium bicarbonate salt. This phenomenon makes it possible to use CO2 to trigger reversible property changes such as a change in the osmotic pressure (π), which is useful for forward osmosis, a membrane-based water separation technique. Chitosan, the deacetylated derivative of the abundant nitrogen-containing natural polymer chitin, is a great biopolymer carrier of desired functionalities through chemical modification. Herein, we report a mechanochemical and aging-based method to functionalize chitosan with a tertiary amine in a one-pot SN2-type aminoalkylation reaction. The reaction afforded chitosan with a high degree of substitution (DS), up to 1.67 per sugar unit, doubling the previously reported DS achieved with solvothermal methods. Unique to this method is its ability to functionalize both the amine and the primary alcohol groups of chitosan. The reaction proceeded well with catalytic amounts of liquid and only stoichiometric amounts of reagent, a favourable improvement upon past reports, which all used excess reagent. It was also scalable and demonstrated on a range of molecular weights. We also showed that O-functionalization was effective on chitin up to a DS of 0.15. The π of aqueous solutions of the aminoalkylated chitosan reversibly increases 47% upon carbonation. This work showcases how mechanochemistry can deliver greatly improved DS on the functionalization of recalcitrant substrates, such as chitinous biomass, with reduced process mass intensity and energy use compared to past works to deliver a CO2-responsive material based on biomass.

This study investigated how the gradual acquisition of object meaning influences different phases of object recognition. Using an interleaved learning and testing procedure, participants were repeatedly exposed to unfamiliar, rare objects while learning about their meaning and function. Across multiple test sessions, event-related brain potentials (ERPs) were recorded to examine changes in early perceptual processing (P1) and later integrative phases of object recognition (N400, late positive complex/LPC) for initially unfamiliar versus well-known objects. Initially, behavioral and ERP differences between rare and familiar objects were pronounced but gradually diminished with learning. For tasks in which object meaning was irrelevant (familiarity classification and naming), increased object knowledge was reflected in a posterior negativity in the N400 window. When object meaning was directly task-relevant (semantic classification), detailed knowledge acquisition was tracked by a later centroparietal component in the LPC window (late relatedness effect). A follow-up test 6 months later showed that these effects were not only remarkably stable but continued to evolve beyond the training period. In contrast, early perceptual processes (P1) showed limited sensitivity to the accumulation of object-specific semantic knowledge. Overall, the findings demonstrate that repeated visual exposure and incremental learning facilitate the deep integration of novel objects into existing semantic networks.

Here we explore three case studies, Wales, Quebec and Manitoba, to examine how changes in multilevel governance affect the strategies and the operating environment of civil society organisations (CSO).1 Every multilevel system of governance has considered ways to share political responsibility for social service delivery, vertically between levels of government and horizontally with non-state organisations. Wales, Quebec and Manitoba all have subnational authority over social policy as a result of devolution (United Kingdom) and constitutional arrangements (Canada). Comparing their experiences suggests shifts in the locus of governance that disrupt established patterns and create opportunities for the redesign of governance arrangements. New dynamics are contingent upon the way that CSOs navigate new structures to position themselves in the policy arena.

There is ongoing debate as to when oxygenic photosynthesis evolved on Earth1,2. Geochemical data from ancient sediments indicate localized or ephemeral photosynthetic O2 production before the Great Oxidation Event (GOE) approximately 2.5–2.3 billion years ago (Ga), and currently suggest Archaean origins, approximately 3 Ga or earlier3, 4, 5, 6, 7, 8–9. However, sedimentary records of the early Earth often suffer from preservation issues, and poor control on the timing of oxidation leaves geochemical proxy data for the ancient presence of O2 open to critique10, 11, 12–13. Here, we report rare Earth element data from three different Archaean carbonate platforms preserved in greenstone belts of the northwest Superior Craton (Canada), which were deposited by the activity of marine photosynthetic bacteria 2.87 Ga, 2.85 Ga and 2.78 Ga. All three indicate O2 production before the GOE in the form of significant depletions in cerium (Ce), reflecting oxidative Ce removal from ancient seawater, as occurs today¹⁴. Using ¹³⁸La-¹³⁸Ce geochronology, we show that La/Ce fractionation, and thus Ce oxidation, occurred at the time of deposition, making these the oldest directly dated Ce anomalies. These results place the origin of oxygenic photosynthesis in the Mesoarchaean or earlier and bring an important new perspective on a long-standing debate regarding Earth’s biological and geochemical evolution.

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The likelihood of forming equivalence classes was influenced by the format used in sorting tests and by four different test criteria applied to the same data set. After 30 participants learned 12 conditional discriminations, MTS tests evaluated the emergence of three 5‐member equivalence classes. These tests were followed by sorting tests that were conducted in clustering or stacking formats. After training, 20% of participants formed the classes. Of the 75% who did not, classes emerged for 36% and 15% of participants during stacking and clustering, respectively, with a criterion of consecutive class‐indicative sorts in the first two sorting tests, and by 45% and 15% of participants during stacking and clustering, respectively, with a criterion of two successive class‐indicative sorts in any of the four sorting tests. Overall, a somewhat higher percentage of participants formed classes during stacking than during clustering, sometimes on a delayed basis. Finally, even higher yields were obtained when criterion was defined as two nonconsecutive class‐indicative sorting tests. When classes did not form, clustering rather than stacking tests generated larger proportions of stereotyped, participant‐defined, three‐member classes and two‐term relations but stacking generated more one‐stimulus “groupings.” Thus, class formation was influenced by sorting format and the criteria used to define class emergence. Also, sorting influenced performances even during failed class formation.

While public opinion and ideology can impact political outcomes in an authoritarian state, measuring and tracking its ideological change remains a challenge. This is largely due to data constraints in nondemocratic contexts, such as limited data on political participation and the scarcity of panel opinion surveys, which are usually costly and tightly controlled by the state. This study proposes a method that relies solely on retweeting ties to produce ideological estimates and to track its changes over time, even in authoritarian settings. Taking Chinese online opinion leaders as an example, this study employs multiple correspondence analysis to estimate the ideological spectrum of these leaders. Results show that, over the past decade, these opinion leaders have gradually shifted toward the conservative/nationalist right with evidence of ideological polarization. The study validates the results against alternative ideological estimates, demonstrating the robustness of the retweet-based approach for tracking ideological changes.