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Journal of Hydrodynamics 2024年第2期36卷 340-354页

作者： Mahboubeh Barahimi Jueyi Sui School of Engineering University of Northern British ColumbiaPrince GeorgeCanada

This study aimed to investigate the previously unexplored effects of ice cover and submerged vegetation on flow *** were undertaken under both open channel and ice-covered flow *** bed material consisted of three non-uniform *** findings revealed that when vegetation patches were present on the bed and an ice cover was present,the velocity profiles exhibited a distinctive pattern with two peak *** kinetic energy(TKE)also exhibited two peaks,one above the vegetation bending height and another at the sheath section,with a decreasing trend towards the ice ***,quadrant analysis showed that when the flow surface is covered by an ice cover,the contributions of inward and outward events increased compared with those observed in an open channel *** most cases,these contributions surpassed the sweep and ejection *** findings enhance our understanding of vegetation’s response to diverse surface conditions and have practical implications for river management and environmental engineering.

关键词： Ice cover vegetation flow structure Reynolds shear stress turbulent kinetic energy(TKE) quadrant analysis

Polymeric piezoelectric accelerometers with high sensitivity,broad bandwidth,and low noise density for organic electronics and wearable microsystems

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Microsystems & Nanoengineering 2024年第3期10卷 63-74页

作者： Chang Ge Edmond Cretu The Department of Electrical and Computer Engineering The University of British ColumbiaVancouverBCCanada

Piezoelectric accelerometers excel in vibration *** the emerging trend of fully organic electronic microsystems,polymeric piezoelectric accelerometers can be used as vital front-end components to capture dynamic signals,such as vocal vibrations in wearable speaking assistants for those with speaking ***,high-performance polymeric piezoelectric accelerometers suitable for such applications are *** organic compounds such as PVDF have inferior properties to their inorganic counterparts such as ***,most existing polymeric piezoelectric accelerometers have very unbalanced performance *** often sacrifice resonance frequency and bandwidth for a flat-band sensitivity comparable to those of PZT-based accelerometers,leading to increased noise density and limited application *** this study,a new polymeric piezoelectric accelerometer design to overcome the material limitations of PVDF is *** new design aims to simultaneously achieve high sensitivity,broad bandwidth,and low *** samples were manufactured and characterized,demonstrating an average sensitivity of 29.45 pC/g within a±10 g input range,a 5%flat band of 160 Hz,and an in-band noise density of 1.4μg/√*** results surpass those of many PZT-based piezoelectric accelerometers,showing the feasibility of achieving comprehensively high performance in polymeric piezoelectric accelerometers to increase their potential in novel applications such as organic microsystems.

关键词： piezoelectric polymeric overcome

Influence of indoor airflow on airborne disease transmission in a classroom

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Building Simulation 2024年第3期17卷 355-370页

作者： Mojtaba Zabihi Ri Li Joshua Brinkerhoff School of Engineering Faculty of Applied ScienceUniversity of British ColumbiaKelownaCanada

It has been widely accepted that the most effective way to mitigate airborne disease transmission in an indoor space is to increase the ventilation airflow,measured in air change per hour(ACH).However,increasing ACH did not effectively prevent the spread of *** better understand the role of ACH and airflow large-scale patterns,a comprehensive fully transient computational fluid dynamics(CFD)simulation of two-phase flows based on a discrete phase model(DPM)was performed in a university classroom setting with people *** investigations encompass various particle sizes,ventilation layouts,and flow *** findings demonstrated that the particle size threshold at which particles are deemed airborne is highly influenced by the background flow strength and large-scale flow pattern,ranging from 5µm to 10µm in the cases *** effects of occupants are significant and must be precisely accounted for in respiratory particle transport *** enhanced ventilation design(UFAD-CDR)for university classrooms is introduced that places a premium on mitigating airborne disease *** to the baseline design at the same ACH,this design successfully reduced the maximum number density of respiratory particles by up to 85%.A novel airflow-related parameter,Horizontality,is introduced to quantify and connect the large-scale airflow pattern with indoor aerosol *** underscores that ACH alone cannot ensure or regulate air *** addition to the necessary ACH for air exchange,minimizing horizontal bulk motion is essential for reducing aerosol transmissibility within the room.

关键词： aerosol transmission airflow pattern horizontality COVID-19 simulation classroom ventilation

T1 colorectal cancer management in the era of minimally invasive endoscopic resection

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World Journal of Gastrointestinal Oncology 2024年第6期16卷 2284-2294页

作者： Shirley Xue Jiang Aein Zarrin Neal Shahidi Department of Medicine University of British ColumbiaVancouver V6Z2K5British ColumbiaCanada Division of Gastroenterology St.Paul’s HospitalVancouver V6Z2K5British ColumbiaCanada

T1 colorectal cancer(CRC),defined by tumor invasion confined to the submucosa,has historically been managed by *** understanding of recurrence and lymph node metastases risk,coupled with advances in endoscopic resection techniques,have led to an increasing capacity for organ-sparing local *** invasive management of T1 CRC begins with optical evaluation of the lesion to diagnose invasive disease and quantify depth of invasion,which informs therapeutic decision *** selection between various available endoscopic resection techniques depends upon lesion characteristics,technique risk-benefit profiles,and location-specific *** endoscopic resection,established histopathology features determine the risk of recurrence and subsequent management including surveillance or adjuvant surgical *** management of non-operative candidates deviates from conventional recommendations with emerging treatment strategies in select populations.

关键词： Cancer Colonoscopy Endoscopy Polyp Surgery

Evolution of biomass particles during pelletization process

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Particuology 2024年第3期86卷 182-187页

作者： Hamid Rezaei Maryam Tajilrou Jun Sian Lee Kanages Singaraveloo Anthony Lau Shahab Sokhansanj Biomass and Bioenergy Research Group Department of Chemical and Biological EngineeringUniversity of British ColumbiaVancouverCanada

Pulverizing is an essential unit operation in co-firing biomass with *** are only compatible with pellet forms of fibrous biomass materials and crush them down to their original forming particle *** is why the data on the size distribution of the particles forming a biomass pellet is crucial to achieving optimum combustion *** current study determines the internal particle size distribution of pellets after wet disintegration,following Iso 17830 standard,and aims to suggest improvements to the mentioned standard based on new measured *** were carried out on white wood pellets(no bark)and brown wood pellets containing bark at four water temperatures:20,40,60,and 95℃,with or without *** particle size distribution of the pre-pelletizer wood particles was also measured and compared with particles in the formed *** water temperature of 20℃ was found to be adequate for the complete disintegration of pellets,and no mechanical stirring was *** 30% of particles in the disintegrated pellets were 0.5-1.0 *** changes the particle size distribution to smaller *** disintegrated bark pellets contained more fines than white pellets.

关键词： Wood pellets Particle sizes distribution Wet disintegration Stirring Water temperature

Long-term monitoring of cycles in Clethrionomys rutilus in the Yukon boreal forest

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Integrative Zoology 2024年第1期19卷 27-36页

作者： Charles J.KREBS Alice J.KENNEY B.Scott GILBERT Rudy BOONSTRA Department of Zoology University of British ColumbiaVancouverBritish ColumbiaCanada Renewable Resources Management Program Yukon UniversityWhitehorseYukonCanada Department of Biological Sciences University of Toronto ScarboroughTorontoOntarioCanada

Baseline studies of small rodent populations in undisturbed ecosystems are *** report here 50 years of mon-itoring and experimentation in Yukon of a dominant rodent species in the North American boreal forest,the red-backed vole Clethrionomys *** voles breed in summer,weigh 20–25 g,and reach a maximum density of 20 to 25 per *** populations have shown consistent 3–4-year cycles for the last 50 years with the only change being that peak densities averaged 8/ha until 2000 and 18/ha since that *** the last 25 years,we have measured food resources,predator numbers,and winter weather,and for 1-year social interactions,to estimate their contribution to changes in the rate of summer increase and the rate of overwinter *** these potential limiting factors could contribute to changes in density,and we measured their relative contributions statistically with multiple *** rate of winter decline in density was related to both food supply and winter *** rate of summer increase was related to summer berry crops and white spruce cone *** measure of predator numbers was related to winter or summer changes in vole *** was a large signal of climate change effects in these *** is no density dependence in summer population growth and only a weak one in winter population *** of our results provide a clear understanding of what generates 3–4-year cycles in these voles,and the major missing piece may be an understanding of social interactions at high density.

关键词： boreal forest climate change density dependence population cycles predation winter severity

Ancient Hakka Walled Villages for Communities

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China Book International 2024年第1期 18-21页

作者： Gong Wenrui Karen Cui Chinese Writers Association society of Translators and Interpreters of british columbia(STIBC)

This book reviews the history and process of the formation of Hakka and reveals the language characteristics,folk beliefs,and spiritual characteristics of the Hakka *** is an excellent book that systematically introdu... 详细信息

关键词： Ancient characteristics culture

SRMD:Sparse Random Mode Decomposition

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Communications on Applied Mathematics and Computation 2024年第2期6卷 879-906页

作者： Nicholas Richardson Hayden Schaeffer Giang Tran University of Waterloo WaterlooONCanada University of british columbia VancouverBCCanada University of California Los AngelesCAUSA

Signal decomposition and multiscale signal analysis provide many useful tools for timefrequency *** proposed a random feature method for analyzing time-series data by constructing a sparse approximation to the *** randomization is both in the time window locations and the frequency sampling,which lowers the overall sampling and computational *** sparsification of the spectrogram leads to a sharp separation between time-frequency clusters which makes it easier to identify intrinsic modes,and thus leads to a new data-driven mode *** applications include signal representation,outlier removal,and mode *** benchmark tests,we show that our approach outperforms other state-of-the-art decomposition methods.

关键词： Sparse random features Signal decomposition Short-time Fourier transform

Gastric cystica profunda:Another indication for minimally invasive endoscopic resection techniques?

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World Journal of Gastroenterology 2024年第27期30卷 3278-3283页

作者： Harjot K Bedi Douglas Motomura Neal Shahidi Department of Medicine University of British ColumbiaVancouver V6Z 2K5BCCanada

Gastric cancer presents a significant global health burden,as it is the fifth most common malignancy and fourth leading cause of cancer mortality *** in incidence rates across regions underscores the multifactorial etiology of this *** overall 5-year survival rate remains low despite advances in its diagnosis and *** surgical gastrectomy was previously standard-of-care,endoscopic resection techniques,including endoscopic mucosal resection and endoscopic submucosal dissection(ESD)have emerged as effective alternatives for early *** to surgical resection,endoscopic resection techniques have comparable 5-year survival rates,reduced treatment-related adverse events,shorter hospital stays and lower *** also enables en bloc resection,thus affording organ-sparing curative endoscopic resection for early *** this editorial,we comment on the recent publication by Geng et al regarding gastric cystica profunda(GCP).GCP is a rare gastric pseudotumour with the potential for malignant *** presents a diagnostic challenge due to its nonspecific clinical manifestations and varied endoscopic *** are several gaps in the literature regarding the diagnosis and management of GCP which warrants further research to standardize patient *** in endoscopic resection techniques offer promising avenues for GCP and early gastric cancers.

关键词： Early gastric cancer Endoscopy Endoscopic submucosal dissection Gastric cystica profunda

Large non-pedunculated colorectal polyp management: The elephant in the room

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World Journal of Gastroenterology 2024年第25期30卷 3126-3131页

作者： Shirley X Jiang Neal Shahidi Department of Medicine University of British ColumbiaVancouver V6Z 2K5BCCanada

Minimally invasive innovations have transformed *** to colorectal cancer(CRC),there has been a shift towards less invasive surgical techniques and use of endoscopic resection as an alternative for low risk T1 *** role of endoscopic resection is however much more extensive:It is now considered the first line management strategy for most large(≥20 mm)non-pedunculated colorectal polyps,the majority of which are *** is due to the well-established efficacy,safety,and cost-effectiveness of endoscopic techniques compared to *** endoscopic modalities now exist with distinct risk-benefit profiles and their outcomes are further improved by site-specific technical modifications,auxiliary techniques,and adverse event miti-gation *** capacity continues to evolve with emerging endoscopic techniques and expanding applications,particularly in the confines of a multi-disciplinary setting.

关键词： Cancer Colonoscopy Endoscopy Polyp Endoscopic mucosal resection Endoscopic submucosal dissection