Natural Sciences and Engineering Research Council

Cryptic species offer opportunities to reveal the mechanisms that constrain phenotypic divergence during speciation. We integrated whole-genome sequencing, morphological, micro- and macro-climatic, and behavioral data to investigate divergence across a well-documented genetic break in the desert-adapted side-blotched lizard, Uta stansburiana, on the Baja California peninsula. Despite deep genomic differentiation, clades show remarkable similarity in morphology, habitat use, and thermal biology. Nearly all genetic differentiation (87%) is explained by isolation by distance and seasonal variation in precipitation, with almost no effect of temperature. Behavioral thermoregulation and changes in activity time accommodate strong macro- and micro-climatic differences, buffering against selection that would otherwise drive morphological and physiological divergence. In contrast, genomic signatures of selection and divergence in genes associated with the nervous system, sensory perception, and biomolecule metabolism indicate adaptation to differences in rainfall seasonality. The results show behavioral flexibility can constrain phenotypic divergence, yielding cryptic species-level genetic divergence despite strong eco-climatic disparities and selection pressures. More broadly, this study shows how rigorous statistical integration of multiple data types can disentangle competing eco-climatic drivers that can decouple phenotype from genotype during speciation.

The progress in the utilization of heavy metal oxide glasses in mid-infrared photonic applications has been hindered by the complication of fabricating thermally stable glass compositions as well as optical fibers with acceptable optical losses. To overcome these obstacles, a range of BaO-Ga 2 O 3 -GeO 2 -Bi 2 O 3 glasses were fabricated by increasing the BaO content while decreasing Bi 2 O 3 . Differential scanning calorimetry studies revealed that the thermal stability of the glasses increases up to 27.5 mol% BaO at which the glass does not yield a crystallization peak even at very low heating rates. High linear and nonlinear refractive index of the glasses were also shown. Spectroscopic properties of the thermally most stable glass were investigated by various Er 3+ -doping content. The luminescence spectra and lifetime values showed suitable results, even with high doping content, for applications requiring optical signal amplification. A multimode optical fiber with an undoped core was drawn by rod-in-tube technique which yielded an optical loss of 10 dB/m for a 3-meter-long fiber. With appropriate precursor purification, glass dehydration and glass fabrication optimization steps, BaO-Ga 2 O 3 -GeO 2 -Bi 2 O 3 glasses are important alternatives to PbO-GeO 2 and TeO 2 -based glasses for MIR applications in optical fiber or bulk glass form. • Thermally stable germanium-gallium-containing bismuthate glasses were fabricated. • Linear and nonlinear optical properties were examined. • Spectroscopic properties were studied by various Er 3+ doping content. • A core/cladding optical fiber was drawn with an optical loss of 10 dB/m at 1500 nm.

• We present a novel method to calculate carbon budgets for individual countries. • The method uses open-source datasets, and can be applied to ∼180 countries. • Four effort-sharing methods lead to a budget of -11–16 GtCO 2 for Canada. • The Canadian building sector seems unlikely to meet its allocated budget share. • There are key scope disparities between life cycle assessment and carbon budgets. Decarbonising the built environment is imperative to reach any net zero global GHG emissions targets. However, there remains uncertainty on how to orchestrate the mitigation efforts. Given a remaining global carbon budget, how should it be assigned both nationally and sectorally? Within this paper, we present a method and Python script to calculate country-specific carbon budgets using open-source datasets, for several scenarios and allocation methods. The script is run for Canada as a case study. Grounded in Canada's calculated carbon budget, tentative budget shares are explored for the Canadian building sector. The feasibility of meeting these budgets is broadly assessed using a streamlined calculation. Even under optimistic assumptions, the Canadian building sector is unlikely to meet its allocated budget share. Key limitations, data requirements and research avenues are highlighted to improve upon the presented approach.

Whether noncombustible or combustible construction is used, the presence of combustible materials is likely to be used for various reasons, such as interior finishes, flooring, and insulation. Consequently, how regulations consider the degree of combustibility in their fire classifications will influence the level of fire safety provided in these buildings and the exchanges between all actors in the construction sector. In North America, the regulation of combustibility is primarily governed by surface flame spread assessed through the Steiner tunnel test. While there is a growing prevalence of calorimetric methods globally, their incorporation into North American building codes remains notably limited. Based on ISO 5660-1 cone calorimeter test results of twenty commercially available North American building materials, a comparative study was conducted between the Canadian flame spread classification and the classifications in Japan, New Zealand and the European Union (Euroclass). The tests and their limitations are described herein, as well as the conceptual frameworks. The results suggest that as materials’ combustibility levels increase, the level of agreement between classifications decreases and remains binary. The choice between the material and system scales is crucial for determining the effective development and implementation of regulations.

The purpose of this study is to evaluate the performance of a Cross-Laminated Timber (CLT) building envelope that employs more bio-based materials, in terms of its hygrothermal behavior and environmental impact. The study involved the construction of four wall assemblies, comparing the effects of the installation of a self-adhesive air barrier on the CLT and the choice of insulation: bio-based wood fiber insulation or stone wool insulation. The walls were subjected to static and dynamic tests in a climate chamber, with temperature and relative humidity sensors installed across the walls. Additionally, the life cycle analysis (LCA) of the identical assemblies was calculated using the Ecoinvent 3.5 database.The findings of the study showed that the wood fiber insulation had a lower relative humidity and a temperature similar to the stone wool insulation. The air barrier reduced the transfer of moisture and increased the temperature across the wall. Furthermore, the wood fiber insulation acted as a moisture buffer, thereby delaying the migration of moisture through the envelope. Concerning the LCA, the metal siding had the highest global warming impact, followed by the insulation types. The wood fiber insulation had a similar impact to the stone wool insulation, except for eutrophication, where stone wool had a lower impact. The air barrier had a negligible impact compared to the rest of the envelope but prevented the CLT wall from being fully recycled. The biogenic carbon stored in the CLT and the wood fiber insulation reduced the global warming potential of the walls.

When an isometric contraction is sustained at a submaximal torque, activation of the motoneuron pool increases, making it difficult to interpret neural excitability alterations. Thus, more recently, isometric contractions with maintained electromyographic (EMG) activity (matched-EMG) are being used to induce fatigue; however, little is known about the neurophysiological adjustments that occur to satisfy the requirements of the task. For our study, 16 participants performed a 10-min sustained isometric elbow flexion contraction at 20% maximal voluntary contraction (MVC) torque or the level of integrated biceps brachii EMG recorded at 20% MVC torque. Surface EMG was used to assess global median frequency, and four fine-wire electrode pairs were used to obtain motor unit (MU) discharge rate from biceps brachii. Torque or EMG steadiness was also assessed throughout the fatiguing contractions. MU discharge rate increased and torque steadiness decreased during the matched-torque contraction; however, MU discharge rate decreased during the matched-EMG contraction, and no changes occurred for EMG steadiness. Data pooled for the two contractions revealed a decrease in global median frequency. Lastly, a greater loss of MVC torque was observed immediately after the matched-torque compared with matched-EMG contraction. These findings indicate that, during a matched-torque fatiguing contraction, the nervous system increases MU discharge rates at the cost of poorer steadiness to maintain the requisite torque. In contrast, during a matched-EMG fatiguing contraction, a reduction of MU discharge rates allows for maintenance of EMG steadiness.

Abstract Materials science plays a critical role in educating future engineers, where knowledge of materials selection is essential for design and problem-solving. However, many programs rely on traditional lecture styles to convey this fundamental knowledge. While these teaching styles can be effective, they provide little opportunity to actively engage and expose learners to memorable experiential learning elements. The COVID-19 pandemic presented a new opportunity to focus on developing unique teaching tools to reach students on virtual platforms. Although the development of these tools was critical in today's technology-driven society, pandemic teaching and learning remained challenging, which likely contributed to the amplification of virtual gamified learning. In redesigning our first-year engineering curriculum within the Faculty of Engineering at McMaster University into the new Integrated Cornerstone Design Projects in Engineering (ENG 1P13) course, an opportunity to re-evaluate our teaching approach was presented, which allowed us to further explore ways to increase student engagement and learner creativity. This work focuses on the introduction of a gamified active-learning approach to teach materials science within the first-year curriculum. The purpose of this intervention was to enhance the learner experience to demystify the fundamentals by connecting theory to practice. Although pedagogical literature highlights the effectiveness of gamified learning strategies to enhance the learning experience, limited examples were found within the materials science and engineering fields. In this work, two types of materials science games along with other interactive lab components were successfully implemented in an adaptable fashion for in-person and virtual teaching styles for over 1200 learners. The first type is adapted based on popular board games in efforts to design relatable understandable games such that the students could focus on learning the new materials and not the game rules, "Materials Battleships", and "Materials Taboo", where gamified strategies are incorporated to introduce students to materials properties and materials selection. The second involves the design of custom virtual emulators that challenge learners to explore the mechanical and electrical behaviour of materials. The games challenged learners to explore various materials and science concepts in a fun way. Our survey responses from participating students were used to evaluate the approach; these findings highlight that gamification stimulated students' interest in material science and motivation to participate. While the majority of students surveyed found the new activities enjoyable, the results also indicate higher learning engagement and increased interest in materials science for upper-level stream selection choice after the open first year. The analysis of these surveys targets what factors were effective in increasing engagement as well as effectiveness in teaching content. The success of gamified learning for material science coupled with the targeted data for improvement and adaption creates a space for significant improvement in the material science curriculum.

Abstract We show that the total variation mixing time is not quasi-isometry invariant, even for Cayley graphs. Namely, we construct a sequence of pairs of Cayley graphs with maps between them that twist the metric in a bounded way, while the ratio of the two mixing times goes to infinity. The Cayley graphs serving as an example have unbounded degrees. For non-transitive graphs, we construct bounded degree graphs for which the mixing time from the worst starting point for one graph is asymptotically smaller than the mixing time from the best starting point of the random walk on a network obtained by increasing some of the edge weights from 1 to $1+o(1)$ .