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Flow structure and shear stress in the presence of both ice cover on water surface and leafless vegetation in channel bed

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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

Investigating low dispersion isotope dissolution Lu-Hf garnet dates via in situ Lu-Hf geochronology,Kanchenjunga Himal

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Geoscience Frontiers 2024年第3期15卷 137-145页

作者： Kyle P.Larson John M.Cottle Mark Button Brendan Dyck Iva Lihter Sudip Shrestha Department of Earth Environmental and Geographic SciencesUniversity of British ColumbiaOkanaganKelownaCanada Department of Earth Science University of CaliforniaSanta BarbaraUSA Fipke Laboratory for Trace Element research University of British ColumbiaOkanaganKelownaCanada

Re-examination of three specimens from the Kanchenjunga Himal of Nepal via in situ Lu-Hf garnet geochronology yields evidence of multiple garnet growth *** analyses from grain cores in two specimens define Paleozoic regressions whereas analyses from grain rims in the same specimens define low-precision regressions consistent with the timing of Himalayan *** dates contrast with previously published low dispersion,ca.290 Ma isotope dissolution(ID)Lu-Hf garnet dates for the same *** of Lu and spot age distribution in representative grains from the specimens examined yields calculated dates that approximate the Permian-age regressions through the original ID *** findings demonstrate that it is possible to generate low dispersion ID Lu-Hf data from multigenerational garnet with significantly different-age growth events when approximately equal proportions of the different age reservoirs are included in multi-component aliquots.

关键词： Lu-Hf geochronology In situ Lu-Hf geochronology Kanchenjunga Himal

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

Characteristics of turbulent flow in 3-D pools in the presence of submerged rigid vegetation in channel bed

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Journal of Hydrodynamics 2024年第1期36卷 158-169页

作者： Kourosh Nosrati Hossein Afzalimehr Jueyi Sui Hamid Reza Reisifar Natural Disasters Prevention research Center Faculty of Civil EngineeringIran University of Science and TechnologyTehranIran School of Engineering University of Northern British ColumbiaPrince GeorgeCanada

In this study,the interaction between 3-D bedforms and submerged rigid vegetation has been *** laboratory experiments were conducted to study the distribution of flow velocity,Reynolds shear stress,turbulent kinetic energy,and skewness coefficients for a constant density of *** showed that the velocity profile in the pool section deviates from those in the upstream section of the *** has been found that the dip parameter varied between 0.6H and 0.9H depending on various factors including bed roughness,vegetation distribution,and pool entrance/exit ***,scattered vegetation in the pool and differences in slopes created non-uniform flow ***,in the wake region behind each vegetated element,flow velocity reduced significantly,and small-scale eddies are formed,causing increased *** decreasing the entrance slope and bed roughness,relatively uniform flow and weaker turbulence was resulted,but the random distribution of vegetated elements counteracted this balance and intensified *** the decrease in the pool entrance slope,the contribution of sweep event decreased and the contribution of ejection event increased.

关键词： Submerged rigid vegetation 3-D pool Reynolds shear stress skewness coefficients

Monogenic features of urolithiasis: A comprehensive review

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Asian Journal of Urology 2024年第2期11卷 169-179页

作者： Kyo Chul Koo Abdulghafour Halawani Victor K.F.Wong Dirk Lange Ben H.Chew Department of Urology Yonsei University College of MedicineSeoulRepublic of Korea Department of Urology King Abdulaziz UniversityJeddahSaudi Arabia Department of Urological Sciences University of British ColumbiaStone Centre at Vancouver General HospitalVancouverBritish ColumbiaCanada

Objective: Urolithiasis formation has been attributed to environmental and dietary factors. However, evidence is accumulating that genetic background can contribute to urolithiasis formation. Advancements in the identification of monogenic causes using high-throughput sequencing technologies have shown that urolithiasis has a strong heritable ***: This review describes monogenic factors implicated in a genetic predisposition to urolithiasis. Peer-reviewed journals were evaluated by a PubMed search until July 2023 to summarize disorders associated with monogenic traits, and discuss clinical implications of identification of patients genetically susceptible to urolithiasis ***: Given that more than 80% of urolithiases cases are associated with calcium accumulation, studies have focused mainly on monogenetic contributors to hypercalciuric urolithiases, leading to the identification of receptors, channels, and transporters involved in the regulation of calcium renal tubular reabsorption. Nevertheless, available candidate genes and linkage methods have a low resolution for evaluation of the effects of genetic components versus those of environmental, dietary, and hormonal factors, and genotypes remain undetermined in the majority of urolithiasis ***: The pathophysiology underlying urolithiasis formation is complex and multifactorial, but evidence strongly suggests the existence of numerous monogenic causes of urolithiasis in humans.

关键词： Gene Genetic expression Inheritance pattern Urolithiasis

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

Lung-protective ventilation in the management of congenital diaphragmatic hernia

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World Journal of Pediatric Surgery 2024年第2期7卷 73-80页

作者： Mike Traynor Department of Anesthesia British Columbia Children's HospitalVancouverBritish ColumbiaCanada

Prioritizing lung-protective ventilation has produced a clear mortality benefit in neonates with congenital diaphragmatic hernia(CDH).While there is a paucity of CDH-specific evidence to support any particular approach to lung-protective ventilation,a growing body of data in adults is beginning to clarify the mechanismsbehind ventilator-induced lung injury and inform safer management of mechanical ventilation in *** review summarizes the adult data and attempts to relate the findings,conceptually,to the CDH *** lessons from the adult studies are that much of the damage done during conventional mechanical ventilation affects normal lung tissue and that most of this damage occurs at the low-volume and high-volume extremes of the respiratory ***,it is important to prevent atelectasis by using sufficient positive end-expiratory pressure while also avoiding overdistention by scaling tidal volume to the amount of functional lung tissue rather than body *** early in acute respiratory distress syndrome improves outcomes,possibly because consistent respiratory mechanics facilitate avoidance of both atelectasis and overdistention—a mechanism that may also apply to the CDH ***-targeted conventional modes may be advantageous in CDH,but determining optimal tidal volume is *** high-frequency oscillatory ventilation and high-frequency jet ventilation have been used successfully as'rescue modes'to avoid extracorporeal membrane oxygenation,and a prospective trial comparing the two high-frequency modalities as the primary ventilation strategy for CDH is underway.

关键词： protective congenital hernia