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Non-fullerene acceptors (NFAs) have enabled power conversion efficiencies exceeding 19% in organic solar cells (OSCs). However, the open-circuit voltage of OSCs remains low relative to their optical gap due to excessive non-radiative recombination, and this now limits performance. Here, we consider an important aspect of OSC design, namely management of the triplet exciton population formed after non-geminate charge recombination. By comparing the blends PM6:Y11 and PM6:Y6, we show that the greater crystallinity of the NFA domains in PM6:Y11 leads to a higher rate of triplet-triplet annihilation (TTA). We attribute this to the four times larger ground state dipole moment of Y11 versus Y6, which improves the long range NFA out-of-plane ordering. Since TTA converts a fraction of the non-emissive triplet states into bright singlet states, it has the potential to reduce non-radiative voltage losses. Through a kinetic analysis of the recombination processes under 1-Sun illumination, we provide a framework for determining the conditions under which TTA may improve OSC performance. If these could be satisfied, TTA has the potential to reduce non-radiative voltage losses by up to several tens of mV and could thus improve OSC performance., Comment: 41 pages, 5 figures

Classroom teachers are expected to have the competencies to teach in inclusive classrooms, with the goal of providing diverse learners the support and opportunities they deserve to learn at their best. However, teachers worldwide have reported their teacher education program was inadequate in preparing them to teach in inclusive classrooms. To address this, Sharma (2018) proposed the 3H framework – the three apprenticeships that preservice teachers should be prepared with to become effective inclusive educators: the heart (attitudes and beliefs of inclusive teachers), the head (knowledge and self-efficacy to teach diverse learners), and the hands (inclusive instructional practices). The goal of this study was to investigate the development of these three apprenticeships in teachers’ early career longitudinally. Eight Canadian beginning teachers were interviewed for four consecutive years about experiences that have contributed to their beliefs, self-efficacy, and instructional practices to teach in diverse classrooms, presented as case studies. Participants’ ideas were further examined collectively, resulting in nine themes: (a) “getting thrown in” to experiment with strategies; (b) gap between theory and reality – what worked or did not work in formal education; (c) what is inclusion?; (d) beliefs in children’s ability and exposure to diverse learners; (e) responsibilities as teachers and recognizing limits; (f) building relationships with students and caregivers; (g) a supportive and knowledgeable team; diversity and other components that affect learning; and (h) books, media, and technology. Developmental patterns were also noted. First, inclusive beliefs and instructional practices taught in teacher education programs were consistently mentioned across the four years of interviews but were not attributed to the influence of their education. Second, participants often began their career with confidence, but it decreased sharply as they experienced a “reality shock”; as time progressed, they either (a) accepted their limits as teachers and met students’ needs to the best of their abilities or (b) felt defeated and lost faith in the inclusive education system. The findings of this study added to our understanding of beginning teachers’ perception of where the issues lie, and directions for improving educational programs so they can better prepare preservice teachers for inclusive education.

This is a replication study of Stroop Effect Study conducted by J. Ridney Stroop in 1935.

Urban trees play an essential role in alleviating the local effects of global warming by sequestering atmospheric carbon dioxide, regulating temperature and reducing air pollution in urban areas. There have been studies estimating carbon sequestration of urban trees using Light Detection and Ranging (LiDAR). Yet, neither of the studies made comparison between species nor extended the discussion towards ecosystem services. Therefore, this study compared the attributes between native and cultivated trees in the Asian Garden of UBC Botanical Garden, estimated their level of above-ground carbon sequestration, and thus examined respective implications in terms of ecosystem services. A canopy height model was first generated from LiDAR point cloud data for individual tree segmentation based on Dalponte algorithm. There were 803 derived trees matched successfully with the field-measured trees in ArcGIS with an accuracy of 69.5%. The level of above-ground carbon sequestration of each tree was estimated from tree height and canopy area using a non-linear regression model. Results showed that the average carbon sequestration level of native trees was higher than cultivated trees by 1102 kg (p = 3.045 x 10-7), which facilitated more effective soil formation. The average canopy areas of both trees were approximately 63 m2 (p = 0.696), which gives rise to their similar contribution in temperature cooling and air purification. In general, the garden provides a high level of biodiversity and education value thanks to its high species diversity. Regarding future directions in garden management, the removal of native trees and the planting location of cultivated trees in the garden should be carefully evaluated since they have higher level of ecosystem services and higher crown area to height ratio respectively. Disclaimer: “UBC SEEDS provides students with the opportunity to share the findings of their studies, as well as their opinions, conclusions and recommendations with the UBC community. The reader should bear in mind that this is a student project/report and is not an official document of UBC. Furthermore readers should bear in mind that these reports may not reflect the current status of activities at UBC. We urge you to contact the research persons mentioned in a report or the SEEDS Coordinator about the current status of the subject matter of a project/report.”

An important lesson learned from the widely-known Gettier cases in epistemology is that no matter how well-justified our beliefs are, knowledge can never be secured— for there could always be some information unbeknownst to us that would undermine our epistemic statuses. In the thesis, I devise a specific approach to epistemic evaluations addressing this problem—inspired by Richard Foley’s (2012) ecumenical account of adequate information on knowledge, as well as Crispin Wright’s (1993, 1994) notion of super-assertibility on truth. In a nutshell, I suggest that one knows just in case one’s belief forming process remains intact upon any expansion of information regarding the epistemic situation. Call this the adequately informed process view on knowledge (AP). Reflecting the interplay between cognitive agency and the external world in the notion of knowledge, the AP account is twofold. On the one hand, it requires a specific display of cognitive process on the agent’s part. Particularly, the belief-forming process must be one such that, an ideal epistemic agent following all relevant epistemic norms would consider it acceptable to form the target belief via that process. Call this epistemic standard acceptable ideality. On the other hand, such acceptable ideality needs to take into account all relevant information available in the case, such that one’s process is deemed acceptably ideal overall in lights of everything that holds in the world. The proposed account of AP adopts a holistic and ecumenical approach to epistemic evaluations. Firstly, I champion the idea that epistemic phenomena are what I call “gestalt phenomena”, in that the epistemic significance of the entire epistemic situation cannot be fully appreciated by individually evaluating the significance of its constituents (such as beliefs, justification, cognitive processes etc.). Instead, any impacts of particular epistemic components should be put under the context of the entire epistemic situation for evaluation. Following such a view, I discuss a few examples of how taking the overall knowledge evaluations as merely consisting in its individual epistemic components has created problems for some of the existing accounts of knowledge—and how taking a holistic perspective might shed light on the situation. Secondly, following Foley, I maintain that knowledge in its nature is ecumenical. The main idea is that while there is only one concept of knowledge—characterised by AP as meeting the acceptable ideality standard considering all available information— there can be many ways to achieve such an epistemic standard (in that one’s cognitive agency can be acceptably ideal for various reasons). AP does not champion any particular epistemic feature as constituting knowledge by itself. Some agency would score better on having certain epistemic goods and some on others. According to AP, S’s belief is adequate if the belief forming process’ “overall score” of ideality given all available information is acceptable. The thesis consists of three parts. Part 1 (Chapters 1 and 2) consists of the introduction of the two approaches and articulation of my positive view. Part 2 (Chapters 3 and 4) consists of theoretical comparisons and further motivations for holism in epistemic evaluations. Part 3 (Chapters 5 and 6) consists of applications of the proposed theoretical framework and its ecumenical nature of epistemic evaluations.

Background Falls in older people is a global public health concern. Physical exercise is a useful and potentially cost-saving treatment option to prevent falls in older people. Objectives We aimed to (1) summarize the research literature regarding the cost-effectiveness of exercise-based programs for falls prevention in older people and (2) discuss the implications of the review's findings for clinical practice and future research on the dosage of cost-effective exercise-based falls prevention programs for older people. Methods Multiple databases were searched from inception until February 2019. Studies were included if they (1) were randomized controlled trials with an economic evaluation of exercise-based falls prevention programs for people ≥ 60 years old and (2) assessed the incremental cost-effectiveness ratios, cost per quality-adjusted life year, incremental cost per fall and benefit-to-cost ratio of programs. Methodological quality was assessed with the Physiotherapy Evidence Database scale and quality of economic evaluation with the Quality of Health Economic Studies. Results We included 12 studies (3668 older people). Interventions for falls prevention were either exercise-only or multifactorial programs. Five studies of high economic quality and 2 of high methodological quality provided evidence supporting exercise-only programs as cost-effective for preventing falls in older people. Specifically, a tailored exercise program including strengthening of lower extremities, balance training, cardiovascular exercise, stretching and functional training of moderate intensity performed twice per week with each session lasting 60 min for ≥ 6 months delivered in groups of 3 to 8 participants with home-based follow-up appears to be cost-effective in preventing falls in older people. Conclusion There is evidence to support exercise-based interventions as cost-effective treatment for preventing falls. Further research is needed to fully establish the cost-effectiveness of such programs, especially in both developing and underdeveloped countries. Review registration PROSPERO CRD42018102892.

Nonconvex optimization problems arise in different research fields and arouse lots of attention in signal processing, statistics and machine learning. In this work, we explore the accelerated proximal gradient method and some of its variants which have been shown to converge under nonconvex context recently. We show that a novel variant proposed here, which exploits adaptive momentum and block coordinate update with specific update rules, further improves the performance of a broad class of nonconvex problems. In applications to sparse linear regression with regularizations like Lasso, grouped Lasso, capped $\ell_1$ and SCAP, the proposed scheme enjoys provable local linear convergence, with experimental justification., 10th NIPS Workshop on Optimization for Machine Learning (NIPS 2017). 8 pages, 4 figures

Literary works reference a variety of globally shared themes including well-known people, events, and time periods. It is particularly interesting to locate patterns that are either invariant across time or exhibit a characteristic change across time, as they could imply something important about society that those works record. This paper suggests the use of Google n-gram viewer as a fast prototyping method for examining time-based properties over a rich sample of literary prose. Using this method, we find that some repeating periods of time, like Sunday, are referenced disproportionally, allowing us to pose questions such as why a day like Thursday is so unpopular. Furthermore, by treating software as a work of prose, we can apply a similar analysis to open-source software repositories and explore time-based relations in commit logs. Doing a simple statistical analysis on a few temporal keywords in the log records, we reinforce and weaken a few beliefs on how college students approach open source software. Finally, we help readers working on their own temporal analysis by comparing the fundamental differences between literary works and code repositories, and suggest blog or wiki as recently-emerging works.