University of British Columbia
  • Vancouver, BC, Canada
Recent publications
The number of forest fires has increased globally, together with considerable smoke emission that significantly impacts the atmospheric environment and associated ecosystems. Most current studies have focused on the in situ effects of fire on the forest ecosystem. However, the mechanisms by which smoke particles affect adjacent ecosystems are largely unexplored. In this study, a simulated forest fire combustion system was developed to evaluate the effect of different smoke concentrations (control, low and high) on soil physico-chemical properties of adjacent farmland at two soil depths. The abundance and diversity of bacterial community were also determined. The results showed that smoke deposition increased the contents of total carbon (TC), total nitrogen (TN), and total phosphorus (TP) in the 0–10 cm soil layer; however, no significant changes in soil water content (SWC) and pH values was observed. The ACE(Abundance Coverage-based estimator) and Chao1 diversity indices of bacterial community generally showed a downward trend whereas the PD_whole_ tree diversity index increased after 180 d of smoke deposition. The relative abundance of Proteobacteria remained stable, while abundance of Firmicutes in soil decreased after 180 d of smoke deposition. Smoke deposition slightly affected the physical and chemical properties of the 10–20 cm soil, but the range of variation of the relative abundance and diversity of dominant bacteria exceeded that of the 0–10 cm soil. A significant positive correlation was found between the soil properties and the alpha diversity indices during the first 30 d after smoke deposition; the correlation then decreased gradually. Redundancy analysis revealed that Proteobacteria, Firmicutes, and Actinobacteria were generally positively correlated with TC, TN, and SWC. As a whole, the study reveals that the effects of smoke deposition on soil physico-chemical properties and bacterial community depends on smoke concentration where relatively low concentration appears to be beneficial to soil bacterial community.
Lithium-metal batteries with high energy/power densities have significant applications in electronics, electric vehicles, and stationary power plants. However, the unstable lithium-metal-anode/electrolyte interface has induced insufficient cycle life and safety issues. To improve the cycle life and safety, understanding the formation of the solid electrolyte interphase (SEI) and growth of lithium dendrites near the anode/electrolyte interface, regulating the electrodeposition/electrostripping processes of Li+, and developing multiple approaches for protecting the lithium-metal surface and SEI layer are crucial and necessary. This paper comprehensively reviews the research progress in SEI and lithium dendrite growth in terms of their classical electrochemical lithium plating/stripping processes, interface interaction/nucleation processes, anode geometric evolution, fundamental electrolyte reduction mechanisms, and effects on battery performance. Some important aspects, such as charge transfer, the local current distribution, solvation, desolvation, ion diffusion through the interface, inhibition of dendrites by the SEI, additives, models for dendrite formation, heterogeneous nucleation, asymmetric processes during stripping/plating, the host matrix, and in situ nucleation characterization, are also analyzed based on experimental observations and theoretical calculations. Several technical challenges in improving SEI properties and reducing lithium dendrite growth are analyzed. Furthermore, possible future research directions for overcoming the challenges are also proposed to facilitate further research and development toward practical applications.
Non-terrestrial networks (NTNs) complement the terrestrial cellular networks by extending coverage to the user equipments (UEs) located in unserved and underserved areas. One of the most critical problems faced by NTN UEs is the lack of uplink (UL) synchronization and the associated initial access failure resulting from the high Doppler frequency offset caused by satellite velocity. While NTN new radio (NR) UEs rely on global navigation satellite system (GNSS) to resolve the UL synchronization problem, it is not always feasible for power-critical NTN Internet-of-Things (IoT) UEs. To this end, we design Synchronization signal-based Positioning in IoT Non-terrestrial networks (SPIN) which enables the IoT UEs to tackle the UL synchronization problem. SPIN estimates position and velocity of the UE using time difference of arrival (TDOA) and frequency difference of arrival (FDOA) measurements on the downlink synchronization signals. Consequently, the UEs can use the position and velocity estimates to compute and compensate for the residual time and frequency offsets, thereby successfully synchronizing to the NTN uplink. We conduct physical layer and system level simulations to show the effectiveness of our solution. SPIN positioning accuracy achieves the Cramér-Rao lower bound and meets the target accuracy required for UL synchronization. We also compare the battery life of an NTN IoT UE which uses SPIN for UL synchronization with that of a UE using GNSS-based solution. Our numerical results show that SPIN has significant battery life savings over GNSS based solution while also maintaining a low computational complexity.
Cascaded multi-level PFC (Power Factor Correction) converters show great potential for applications that require high AC voltage input but low DC bus voltage output, such as telecom power supply, battery formation, and Internet data centers. They are compact and put less voltage stress on power switches. To provide multi DC out ports with fewer power switches, a cascaded half-bridge based multi-level multi-port bridgeless PFC is proposed in this paper. Compared with cascaded full-bridge multi-level PFC, the number of switches per power cell for the proposed PFC is reduced by half while maintaining the same DC out ports. Due to the multi-level voltage, the volt-second on the boost inductor decreases, reducing the current ripple of the proposed PFC by $2n$ times with the same boost inductance as the conventional totem pole PFC. By splitting the power into $2n$ cells with low voltage, the total switching losses are also reduced by $2n$ times with the same equivalent switching frequency. Additionally, the proposed rectifier also reduces conduction losses as lower voltage switches with smaller conduction loss are adopted in half-bridge cells compared with conventional totem pole PFC rectifiers. Finally, these benefits are analyzed and validated with experiments.
The literature on “benign overfitting” in overparameterized models has been mostly restricted to regression or binary classification; however, modern machine learning operates in the multiclass setting. Motivated by this discrepancy, we study benign overfitting in multiclass linear classification. Specifically, we consider the following training algorithms on separable data: (i) empirical risk minimization (ERM) with cross-entropy loss, which converges to the multiclass support vector machine (SVM) solution; (ii) ERM with least-squares loss, which converges to the min-norm interpolating (MNI) solution; and, (iii) the one-vs-all SVM classifier. First, we provide a simple sufficient deterministic condition under which all three algorithms lead to classifiers that interpolate the training data and have equal accuracy. When the data is generated from Gaussian mixtures or a multinomial logistic model, this condition holds under high enough effective overparameterization. We also show that this sufficient condition is satisfied under “neural collapse”, a phenomenon that is observed in training deep neural networks. Second, we derive novel bounds on the accuracy of the MNI classifier, thereby showing that all three training algorithms lead to benign overfitting under sufficient overparameterization. Ultimately, our analysis shows that good generalization is possible for SVM solutions beyond the realm in which typical margin-based bounds apply.
RESUMO A produção de dados em uma oficina de educação permanente em saúde sobre as práticas e saberes profissionais envolvendo a alimentação de crianças e adolescentes em territórios periféricos apontou a potência do encontro para o reconhecimento do próprio saber-fazer e do trabalho/conhecimento do outro no cotidiano do cuidado. Reconheceu o alimento como mediador de redes territoriais que envolvem a cadeia curta de produção-comercialização de alimentos que valorizam o saber popular para além do nutricionista como único detentor do saber sobre alimentação. A oficina convidou ao pensamento sobre as relações da equipe e da rede territorial, que não acontecem sem disputas e nem sempre resultam em respostas rápidas e fáceis.
To combat climate change, carbon dioxide must be prevented from entering the atmosphere or even removed from it. Biochar is one potential practice to sequester carbon, but its climate change mitigation potential depends on a multitude of parameters. Differentiating areas of low and high climate change mitigation through biochar addition is key to maximize its potential and effectively use the available feedstock for its production. This study models the realistic application of 1 metric tonne (t) per hectare (ha) of forest harvest residue derived biochar over the climatically and pedologically diverse agricultural area of British Columbia, Canada, and provides a framework and assumptions for reproducibility in other parts of the world. The model accounts for the direct (input of organic carbon) and indirect (enhanced plant biomass) effects of biochar on soil organic carbon stock, its impact on nitrous oxide emissions from soils, and the avoided emissions from the reduced lime requirement due to biochar's alkalinization potential. Impacts are modelled over 20‐year time horizon to account for the duration and magnitude variation over time of biochar effect on plant biomass and nitrous oxide emissions from soil and conform to the IPCC GWP 20‐year time horizon reporting. The results show that a single application of 1 t of biochar per ha⁻¹ can mitigate between 3 and 5 t CO2e ha⁻¹ over a 20‐year time frame. Applied to the 746,000 ha of agricultural land of British Columbia this translate to the mitigation of a total of 2.5 million metric tonnes (Mt) CO2e over a 20‐year time frame. Further, the results identify agricultural areas in the Lower Mainland region (the southwestern corner of British Columbia) as the area maximizing climate change mitigation potential through biochar addition due to a combination of relative high temperature, high precipitation, and crops with high nitrogen requirement.
  • Yu Luo
    Yu Luo
  • Andrew Li
    Andrew Li
  • Dilip Soman
    Dilip Soman
  • Jiaying Zhao
    Jiaying Zhao
Public and private institutions have gained traction in developing interventions to alter people's behaviours in predictable ways without limiting the freedom of choice or significantly changing the incentive structure. A nudge is designed to facilitate actions by minimizing friction, while a sludge is an intervention that inhibits actions by increasing friction, but the underlying cognitive mechanisms behind these interventions remain largely unknown. Here, we develop a novel cognitive framework by organizing these interventions along six cognitive processes: attention, perception, memory, effort, intrinsic motivation and extrinsic motivation. In addition, we conduct a meta-analysis of field experiments (i.e. randomized controlled trials) that contained real behavioural measures (n = 184 papers, k = 184 observations, N = 2 245 373 participants) from 2008 to 2021 to examine the effect size of these interventions targeting each cognitive process. Our findings demonstrate that interventions changing effort are more effective than interventions changing intrinsic motivation, and nudge and sludge interventions had similar effect sizes. However, these results need to be interpreted with caution due to a potential publication bias. This new meta-analytic framework provides cognitive principles for organizing nudge and sludge with corresponding behavioural impacts. The insights gained from this framework help inform the design and development of future interventions based on cognitive insights.
  • Katherine E McLeod
    Katherine E McLeod
  • Jane A Buxton
    Jane A Buxton
  • Ruth Elwood Martin
    Ruth Elwood Martin
In 2017, British Columbia (BC) transferred responsibility for healthcare services in provincial correctional facilities from the Ministry of Public Safety and Solicitor General to the Ministry of Health. This study explored how healthcare leadership perceived the impact of the transfer on services, work-life, and job satisfaction. We conducted one-on-one interviews ( n = 8) with healthcare managers and medical and administrative leadership within Correctional Health Services. Using the Two-Factor theory of job satisfaction as a framework, we applied Interpretive Description methodology to analyse interview data. Participants identified changes to four areas of the working environment: (1) staffing, equipment, and resources (2) systems of supervision and support (3) standards, policies, and quality improvement and (4) culture and orientation. These changes predominantly affected motivational factors of job satisfaction and were described as enriching the roles of managers and staff. Participants described improved autonomy and recognition of providers, increased quality of services delivered, and a shift toward patient-centred care. The perspectives of healthcare leaders provide new insight into the potential impact of transferring healthcare services in custody to a public healthcare system. Discussion of changes and their affects also provide practical learning for jurisdictions seeking to improve healthcare under a variety of governance and service-delivery models.
  • Kathleen M Sturgeon
    Kathleen M Sturgeon
  • Dieuwertje E Kok
    Dieuwertje E Kok
  • Ian R Kleckner
    Ian R Kleckner
  • [...]
  • Kerri Winters-Stone
    Kerri Winters-Stone
Introduction The American College of Sports Medicine provided guidelines for exercise prescriptions in cancer survivors for specific cancer‐ and treatment‐related health outcomes. However, there was insufficient evidence to generate exercise prescriptions for 10 health outcomes of cancer treatment. We sought to update the state of evidence. Methods We conducted a systematic review of these 10 understudied health outcomes (bone health, sleep, cardiovascular function, chemotherapy‐induced peripheral neuropathy (CIPN), cognitive function, falls and balance, nausea, pain, sexual function, and treatment tolerance) and provided an update of evidence. Results While the evidence base for each outcome has increased, there remains insufficient evidence to generate exercise prescriptions. Common limitations observed across outcomes included: variability in type and quality of outcome measurement tools, variability in definitions of the health outcomes, a lack of phase III trials, and a majority of trials investigating breast or prostate cancer survivors only. Conclusion We identified progress in the field of exercise oncology for several understudied cancer‐ and treatment‐related health outcomes. However, we were not able to generate exercise prescriptions due to continued insufficient evidence base. More work is needed to prescribe exercise as medicine for these understudied health outcomes, and our review highlights several strategies to aid in research acceleration within these areas of exercise oncology.
  • Hamidreza Aftabi
    Hamidreza Aftabi
  • Benedikt Sagl
    Benedikt Sagl
  • John Lloyd
    John Lloyd
  • [...]
  • Sidney Fels
    Sidney Fels
Advanced cases of head and neck cancer involving the mandible often require surgical removal of diseased sections and subsequent replacement with donor bone. During the procedure, the surgeon has to decide which soft tissues structures to resect (especially muscles). This requires balancing tradeoffs related to issues such as surgical access and post-operative function; however, the latter is often difficult to predict, especially given that long-term functionality also depends on the impact of post-operative rehabilitation programs. To assist in surgical decision-making, we present an approach to estimating effects of typical muscle resections on key aspects of post-operative function. We validate our dynamic biomechanical models of the reconstructed mandible using literature data and use these models to estimate the degree of functionality that might be achieved following post-operative rehabilitation. We find significant potential for restoring mandibular functionality, even in cases involving large defects. This entails an average trajectory error below 2 mm, bite force comparable to a healthy individual, improved condyle mobility, and a muscle activation change capped at a maximum of 20%. These results suggest that there is significant potential for improving post-operative rehabilitation to gain greater restoration of jaw function.
  • John H. V. Gilbert
    John H. V. Gilbert
  • Marie-Andree Girard
    Marie-Andree Girard
  • Ruby E. Grymonpre
    Ruby E. Grymonpre
  • [...]
  • Barbara Maxwell
    Barbara Maxwell
Background This article focuses on a growing, global recognition of the importance of the field of interprofessional education for person-centered collaborative practice (IPECP) expressed through high-level policy and accreditation decisions/actions taking place in 5 countries. Policy decisions are used to motivate strategies related to IPECP that align with national health plans, and workforce issues. Methods Using a collective of representative stories from around the globe, a grouping of case studies were developed to illustrate different approaches and challenges to IPECP implementation. Results Institutions from countries of various income levels face many similar challenges in the execution, delivery, and sustainability of IPECP. All programs face issues of financing, of preparing faculty, of developing and organizing curricula, and of bridging between campus and community. Discussion Policies are being developed that promote a global approach to the inclusion of IPECP in the accreditation and regulation of postsecondary institutions and health service organizations, in keeping with WHO National Health Workforce Accounts. Policies developed promote and demonstrate the benefits of IPECP through remote emergency learning methods. The policies also build national systems for IPECP as an integral part of continuing professional development and lifelong learning. The organization of interprofessional research programs and the increasing publication of their results of such programs will lead to a clearer understanding of the efficacy of the field of IPECP. To ensure sustainability, stakeholders and policymakers should continue to foster policies that facilitate IPECP.
Pathological narcissism is a personality constellation comprising distorted self-image, maladaptive self-esteem regulation , and difficulties in intimate relationships. Patients with elevated pathological narcissism may not necessarily meet criteria for narcissistic personality disorder, and may seek treatment for a range of mental health concerns across various clinical settings. An understanding of key principles of control-mastery theory (CMT) can help clinicians understand the specific goals and challenges of the individual patient with pathological narcissism, and can illuminate ways in which the patient may work in psychotherapy. This paper outlines how patients with pathological narcissism may engage in testing of their pathogenic beliefs, and how therapists can respond in ways that facilitate the patient's sense of safety and foster psychological work. The role of the therapist's attitude is highlighted as a means for countering pathogenic beliefs associated with pathological narcissism. Clinical material from a single case of time-limited supportive psychotherapy will be used to illustrate these principles and associated therapeutic processes. Insights from CMT regarding pathogenic beliefs and the patient's plan for addressing them can help to explain how therapy works or does not work for patients with pathological narcissism. K E Y W O R D S case formulation, control-mastery theory, identity, narcissism, psychotherapy J Clin Psychol. 2023;1-14.
  • Boning Yang
    Boning Yang
  • Huili Wang
    Huili Wang
  • Qijing Xia
    Qijing Xia
  • [...]
  • Wei Li
    Wei Li
The conservation of genetic diversity is a crucial aspect of forest tree breeding programs, necessitating strategies for its safeguard. Here, the extent of genetic diversity was assessed in 260 Chinese pine (Pinus tabuliformis Carr.) germplasm samples from five provenances using 24 SSR markers. We systematically compared various methods for constructing a core collection aimed at conserving genetic diversity and the results revealed substantial genetic diversity within this germplasm collection. Extensive gene exchange was observed among four of the sampled five provenances which resulted in forming two genetically distinctive groups. To construct the core collection, six different sampling strategies (PowerCore, Power marker_allele number, Power marker_gene entropy, Power marker_gene diversity, Corehunter, and genetic distance-based) and five different sampling sizes (ranging from 10 to 30%) were employed. Comparative analysis of genetic diversity parameters was conducted across the identified 26 subsets, utilizing the PowerCore strategy as the primary approach for capturing all allelic variation present in the core collection, which consisted of only 61 individuals. A supplementary collection of 20 individuals with high genetic variation was identified to provide a final core collection of 81 individuals, representing 31.2% of the initial collection. The constructed core collection effectively captured the genetic diversity present in the initial collection and serves as a valuable resource for preserving genetic richness within the breeding population.
  • Jordyn Rice
    Jordyn Rice
  • Linda C. Li
    Linda C. Li
  • Jennifer C. Davis
    Jennifer C. Davis
  • [...]
  • Teresa Liu-Ambrose
    Teresa Liu-Ambrose
Background Limited mobility in older adults consistently predicts both morbidity and mortality. As individuals age, the rates of mobility disability increase from 1.0% in people aged 15–24 to 20.6% in adults over 65 years of age. Physical activity can effectively improve mobility in older adults, yet many older adults do not engage in sufficient physical activity. Evidence shows that increasing physical activity by 50 min of moderate intensity physical activity in sedentary older adults with mobility limitations can improve mobility and reduce the incidence of mobility disability. To maximize the healthy life span of older adults, it is necessary to find effective and efficient interventions that can be delivered widely to prevent mobility limitations, increase physical activity participation, and improve quality of life in older adults. We propose a randomized controlled trial to assess the effect of a physical activity health coaching intervention on mobility in older adults with mobility limitations. Methods This randomized controlled trial among 290 (145 per group) community-dwelling older adults with mobility limitations, aged 70–89 years old, will compare the effect of a physical activity health coaching intervention versus a general healthy aging education program on mobility, as assessed with the Short Physical Performance Battery. The physical activity health coaching intervention will be delivered by exercise individuals who are trained in Brief Action Planning. The coaches will use evidence-based behavior change techniques including goal-setting, action planning, self-monitoring, and feedback to improve participation in physical activity by a known dose of 50 min per week. There will be a total of 9 health coaching or education sessions delivered over 26 weeks with a subsequent 26-week follow-up period, wherein both groups will receive the same duration and frequency of study visits and activities. Discussion The consequences of limited mobility pose a significant burden on the quality of life of older adults. Our trial is novel in that it investigates implementing a dose of physical activity that is known to improve mobility in older adults utilizing a health coaching intervention. Trial registration Protocol Registration System: NCT05978336; registered on 28 July 2023.
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22,616 members
Lorienne Jenstad
  • School of Audiology and Speech Sciences
Philipp F Lange
  • Department of Pathology and Laboratory Medicine
Jean Carruthers
  • Department of Ophthalmology and Visual Sciences
Matt D A Fletcher
  • Department of Orthopaedics
1984 Main Mall, V6T 1Z2, Vancouver, BC, Canada
Head of institution
Dr. Brian Wetton
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