Large-eddy simulation and wind tunnel study of flow over an up-hill slope in a complex terrain

Tsang, C.F.,Kwok, Kenny C.S.,Hitchcock, Peter A.,Hui, Desmond K.K. Techno-Press 2009 Wind and Structures, An International Journal (WAS Vol.12 No.3

This study examines the accuracy of large-eddy simulation (LES) to simulate the flow around a large irregular sloping complex terrain. Typically, real built up environments are surrounded by complex terrain geometries with many features. The complex terrain surrounding The Hong Kong University of Science and Technology campus was modelled and the flow over an uphill slope was simulated. The simulated results, including mean velocity profiles and turbulence intensities, were compared with the flow characteristics measured in a wind tunnel model test. Given the size of the domain and the corresponding constraints on the resolution of the simulation, the mean velocity components within the boundary layer flow, especially in the stream-wise direction were found to be reasonably well replicated by the LES. The turbulence intensity values were found to differ from the wind tunnel results in the building recirculation zones, mostly due to the constraints placed on spatial and temporal resolutions. Based on the validated mean velocity profile results, the flow-structure interactions around these buildings and the surrounding terrain were examined.

Risk factors for child physical abuse and neglect among Chinese young mothers

Lo, Camilla K.M.,Tung, Keith T.S.,Chan, Ko Ling,Yip, Paul S.F.,Lau, Joseph T.F.,Wong, Wilfred H.S.,Wong, Rosa S.,Tsang, Anita M.C.,Tsang, Hannah Y.H.,Tso, Winnie W.Y.,Ip, Patrick Elsevier 2017 Child abuse & neglect Vol.67 No.-

<P><B>Abstract</B></P> <P>Although studies have reported a linkage between young pregnancy and child maltreatment risk, it is still unclear about what factors place young mothers at greater risk of maltreating their child in Chinese context. Based on the socio-ecological model, risk factors in 4 domains: family background/structure, maternal stressors, mother-child interaction, and child behavioral issue in relation to physical assault, neglect, both physical assault and neglect, and either physical assault or neglect among Chinese young mothers in Hong Kong were assessed. 392 young mothers were recruited from an integrated supportive program for young mothers. The mean age of mothers at delivery was 21.8 (SD=3.0) and 52.3% were married. Individual risk factors and cumulative risk domains related to different child maltreatment groups were examined. Our results show both overlapping and unique risk factors across the domains associated with physical assault and neglect. Further, young families exposed to higher number of risk domains show higher rates for physical assault and neglect, co-occurrence of physical assault and neglect, and either form of maltreatment. In addition, various risk domains were found to be particularly important for different forms of maltreatment: family background/structure domain was found to be an important risk domain for neglect; mother-child interaction domain for both physical assault and neglect; family background/structure and maternal stressors domains for either physical assault or neglect. Closer examination of a subgroup of adolescent mothers aged 18 and below shows that family background/structure was an important risk domain for this group.</P>

Cadmium phytoremediation potential of <i>Brassica</i> crop species: A review

Rizwan, Muhammad,Ali, Shafaqat,Zia ur Rehman, Muhammad,Rinklebe, Jö,rg,Tsang, Daniel C.W.,Bashir, Arooj,Maqbool, Arosha,Tack, F.M.G.,Ok, Yong Sik Elsevier 2018 Science of the Total Environment Vol.631 No.-

<P><B>Abstract</B></P> <P>Cadmium (Cd) is a highly toxic metal released into the environment through anthropogenic activities. Phytoremediation is a green technology used for the stabilization or remediation of Cd-contaminated soils. <I>Brassica</I> crop species can produce high biomass under a range of climatic and growing conditions, allowing for considerable uptake and accumulation of Cd, depending on species. These crop species can tolerate Cd stress via different mechanisms, including the stimulation of the antioxidant defense system, chelation, compartmentation of Cd into metabolically inactive parts, and accumulation of total amino-acids and osmoprotectants. A higher Cd-stress level, however, overcomes the defense system and may cause oxidative stress in <I>Brassica</I> species due to overproduction of reactive oxygen species and lipid peroxidation. Therefore, numerous approaches have been followed to decrease Cd toxicity in <I>Brassica</I> species, including selection of Cd-tolerant cultivars, the use of inorganic and organic amendments, exogenous application of soil organisms, and employment of plant-growth regulators. Furthermore, the coupling of genetic engineering with cropping may also help to alleviate Cd toxicity in <I>Brassica</I> species. However, several field studies demonstrated contrasting results. This review suggests that the combination of Cd-tolerant <I>Brassica</I> cultivars and the application of soil amendments, along with proper agricultural practices, may be the most efficient means of the soil Cd phytoattenuation. Breeding and selection of Cd-tolerant species, as well as species with higher biomass production, might be needed in the future when aiming to use <I>Brassica</I> species for phytoremediation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> <I>Brassica</I> species can be considered a potential candidate for Cd phytoremediation. </LI> <LI> <I>Brassica</I> species can accumulate most of the soil Cd in its parts. </LI> <LI> Different amendments can be applied to enhance Cd tolerance in <I>Brassica</I> species. </LI> <LI> Integrated agricultural practices can be used to enhance Cd uptake in <I>Brassica</I> species. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Cardiac Phenotyping of SARS-CoV-2 in British Columbia: A Prospective Echo Study With Strain Imaging

Jeffrey Yim,Michael Y.C. Tsang,Anand Venkataraman,Shane Balthazaar,Ken Gin,John Jue,Parvathy Nair,Christina Luong,Darwin F. Yeung,Robb Moss,Sean A Virani,Jane McKay,Margot Williams,Eric C. Sayre,Puran 한국심초음파학회 2023 Journal of Cardiovascular Imaging (J Cardiovasc Im Vol.31 No.3

BACKGROUND: There is limited data on the residual echocardiographic findings including strain analysis among post-coronavirus disease (COVID) patients. The aim of our study is to prospectively phenotype post-COVID patients. METHODS: All patients discharged following acute COVID infection were systematically followed in the post-COVID-19 Recovery Clinic at Vancouver General Hospital and St. Paul’s Hospital. At 4–18 weeks post diagnosis, patients underwent comprehensive echocardiographic assessment. Left ventricular ejection fraction (LVEF) was assessed by 3D, 2D Biplane Simpson’s, or visual estimate. LV global longitudinal strain (GLS) was measured using a vendor-independent 2D speckle-tracking software (TomTec). RESULTS: A total of 127 patients (53% female, mean age 58 years) were included in our analyses. At baseline, cardiac conditions were present in 58% of the patients (15% coronary artery disease, 4% heart failure, 44% hypertension, 10% atrial fibrillation) while the remainder were free of cardiac conditions. COVID-19 serious complications were present in 79% of the patients (76% pneumonia, 37% intensive care unit admission, 21% intubation, 1% myocarditis). Normal LVEF was seen in 96% of the cohort and 97% had normal right ventricular systolic function. A high proportion (53%) had abnormal LV GLS defined as < 18%. Average LV GLS of septal and inferior segments were lower compared to that of other segments. Among patients without pre-existing cardiac conditions, LVEF was abnormal in only 1.9%, but LV GLS was abnormal in 46% of the patients. CONCLUSIONS: Most post-COVID patients had normal LVEF at 4–18 weeks post diagnosis, but over half had abnormal LV GLS.

Large-eddy simulation and wind tunnel study of flow over an up-hill slope in a complex terrain

C. F. Tsang,Kenny C. S. Kwok,Peter A. Hitchcock,Desmond K. K. Hui 한국풍공학회 2009 Wind and Structures, An International Journal (WAS Vol.12 No.3

This study examines the accuracy of large-eddy simulation (LES) to simulate the flow around a large irregular sloping complex terrain. Typically, real built up environments are surrounded by complex terrain geometries with many features. The complex terrain surrounding The Hong Kong University of Science and Technology campus was modelled and the flow over an uphill slope was simulated. The simulated results, including mean velocity profiles and turbulence intensities, were compared with the flow characteristics measured in a wind tunnel model test. Given the size of the domain and the corresponding constraints on the resolution of the simulation, the mean velocity components within the boundary layer flow, especially in the stream-wise direction were found to be reasonably well replicated by the LES. The turbulence intensity values were found to differ from the wind tunnel results in the building recirculation zones, mostly due to the constraints placed on spatial and temporal resolutions. Based on the validated mean velocity profile results, the flow-structure interactions around these buildings and the surrounding terrain were examined.

Harmonics Characterization of Transistors

K. F. Tsang,P. C. L. Yip,G. B. Morgan 대한전자공학회 1993 JTC-CSCC : Joint Technical Conference on Circuits Vol.- No.-