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Study of the attenuation relationship for the Wenchuan m_s 8.0 earthquake

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Earthquake Engineering and Engineering Vibration 2015年第1期14卷 1-11页

作者： Sin-Chi Kuok Iok-Tong ng ka-Veng Yuen Faculty of Science and Technology University of Macao

Prediction of peak ground acceleration is an essential element in engineering seismology and it has received great attention in last few decades. In this paper, a comprehensive database of the strong-motion records of the 2008 great Wenchuan ms 8.0 earthquake is analyzed to investigate the seismic attenuation relationship and the directivity effects. In contrast to most existing seismic attenuation models, the proposed model considers explicitly the directivity effect which has primary influence on the magnitude of ground motion. Bayesian model updating is used to obtain the model parameters and the associated uncertainty. Comparative study is performed with the well-known Boore-Joyner-Fumal empirical formula. Results show that consideration of the directivity effect is vital in modeling the seismic attenuation relationship.

关键词： Bayesian inference Boore-Joyner-Fumal attenuation relationship directivity peak ground acceleration seismic attenuation model

Exacerbated VEGF up-regulation accompanies diabetes-aggravated hemorrhage in mice after experimental cerebral ischemia and delayed reperfusion

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Neural Regeneration Research 2022年第7期17卷 1566-1575页

作者： Angela ka Wai Lai Tsz Chung ng Victor ka Lok Hung ka Cheung Tam Chi Wai Cheung Sookja Kim Chung Amy Cheuk Yin Lo Department of Ophthalmology Li Ka Shing Faculty of MedicineThe University of Hong KongHong Kong Special Administration RegionChina Department of Anesthesiology Laboratory and Clinical Research Institute for PainThe University of Hong KongHong Kong Special Administration RegionChina macao University of Science and Technology TaipaMacao Special Administration RegionChinaSchool of Biomedical SciencesThe State Key Laboratory of Pharmaceutical BiotechnologyThe University of Hong KongHong Kong Special Administration RegionChina

Reperfusion therapy is the preferred treatment for ischemic stroke,but is hindered by its short treatment window,especially in patients with diabetes whose reperfusion after prolonged ischemia is often accompanied by exacerbated *** mechanisms underlying exacerbated hemorrhage are not fully *** study aimed to identify this mechanism by inducing prolonged 2-hour transient intraluminal middle cerebral artery occlusion in diabetic Ins2Akita/+mice to mimic patients with diabetes undergoing delayed mechanical *** results showed that at as early as 2 hours after reperfusion,Ins2Akita/+mice exhibited rapid development of neurological deficits,increased infarct and hemorrhagic transformation,together with exacerbated down-regulation of tight-junction protein ZO-1 and upregulation of blood-brain barrier-disrupting matrix metallopeptidase 2 and matrix metallopeptidase 9 when compared with normoglycemic Ins2+/+*** indicated that diabetes led to the rapid compromise of vessel integrity immediately after reperfusion,and consequently earlier death and further aggravation of hemorrhagic transformation 22 hours after *** observation was associated with earlier and stronger up-regulation of pro-angiogenic vascular endothelial growth factor(VEGF)and its downstream phospho-Erk1/2 at 2 hours after reperfusion,which was suggestive of premature angiogenesis induced by early VEGF up-regulation,resulting in rapid vessel disintegration in diabetic *** reticulum stress-related pro-apoptotic C/EBP homologous protein was overexpressed in challenged Ins2Akita/+mice,which suggests that the exacerbated VEGF up-regulation may be caused by overwhelm.ng endoplasmic reticulum stress under diabetic *** conclusion,the results mimicked complications in patients with diabetes undergoing delayed mechanical thrombectomy,and diabetes-induced accelerated VEGF up-regulation is likely to underlie exacerbated hemorrhagic transformat

关键词： blood-brain barrier brain injury diabetes mellitus hemorrhagic transformation infarct ischemia/reperfusion injury middle cerebral artery occlusion mouse model stroke vascular endothelial growth factor

Effectiveness of air cleaner on mitigating the transmission of respiratory disease in a dental clinic environment

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Building Simulation 2024年第10期17卷 1789-1803页

作者： Gang Yang Yifan Wang ka Chung Chan Kwok Wai mui Thomas F.Flemmig SThomas ng Christopher Y.H.Chao Sau Chung Fu Department of Building Environment and Energy Engineering The Hong Kong Polytechnic UniversityHong KongChina Faculty of Dentistry The University of Hong KongHong KongChina Department of Architecture&Civil Engineering City University of Hong KongHong KongChina Department of mechanical Engineering The Hong Kong Polytechnic UniversityHong KongChina

In dental clinics with an open floor plan,the risk of patient-to-patient transmission of respiratory disease is a *** dental procedures large amounts of bioaerosol are produced and patients cannot wear personal protective *** paper examines how to effectively deploy air cleaner to reduce the infection risk in dental clinics with an open floor *** locations of air cleaners at various clean air delivery rates(CADRs)were *** dispersion of bioaerosol was studied through numerical simulations,and risk assessment was performed by a dose-response *** findings indicated that dental patients downstream of the background ventilation have a higher infection risk than those to the left and right of an infected patient(i.e.,the source).The lowest infection risks for the adjacent patients were found when the air cleaner was place opposite to the dentists,i.e.,on the floor at low CADR levels of 2.2 m^(3)/min or on the bench at CADR levels of 4.4 m^(3)/min or *** results of this study indicated that air cleaner can mitigate the risk of patient-to-patient transmission of SARS-CoV-2 in dental clinics with an open floor *** CADR levels determine the optimal placement of air cleaners.

关键词： infection risk air cleaner location dental clinic CFD simulation respiratory disease

multi-exponential model to describe pressure-dependent P-and S-wave velocities and its use to estimate the crack aspect ratio

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Journal of Rock mechanics and Geotechnical Engineering 2022年第2期14卷 385-395页

作者： mihály Dobróka Norbert Péter Szabó Tünde Edit Dobróka mátyás Krisztián Baracza Department of Geophysics University of MiskolcMiskolc-Egyetemváros3515Hungary mTA-mE Geoengineering Research Group University of MiskolcMiskolc-Egyetemváros3515Hungary Research Institute of Applied Earth Sciences University of MiskolcMiskolc-Egyetemváros3515Hungary

We present new quantitative model describing the pressure dependence of acoustic P-and S-wave *** that a variety of individual mechanisms or defects(such as cracks,pore collapse and grain crushing)can contribute to the pressure-dependent change of the wave velocity,we order a characteristic pressure to all of them and allow a series of exponential terms in the description of the(Pand S-waves)velocity-pressure *** estimate the parameters of the multi-exponential rock physical model in inversion procedures using laboratory measured P-and S-wave velocity *** is known,the conventional damped least squares method gives acceptable results only when one or two individual mechanisms are *** the number of exponential terms leads to highly nonlinear ill-posed inverse *** to this reason,we develop the spectral inversion method(SIm)in which the velocity amplitudes(the spectral lines in the characteristic pressure spectrum)are only considered as *** characteristic pressures(belonging to the velocity amplitudes)are excluded from the set of inversion unknowns,instead,they are defined in a set of fixed positions equidistantly distributed in the actual interval of the independent variable(pressure).Through this novel linear inversion method,we estimate the parameters of the multi-exponential rock physical model using laboratory measured P-and S-wave velocity *** characteristic pressures are related to the closing pressures of cracks which are described by well-known rock mechanical relationships depending on the aspect ratio of elliptical *** gives the possibility to estimate the aspect ratios in terms of the characteristic pressures.

关键词： multi-exponential rock physical model Spectral inversion method(SIm) Crack aspect ratio Characteristic pressures

Tribonacci Partition Formulas modulo m

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Acta mathematica Sinica,English Series 2010年第3期26卷 465-476页

作者： Ji■í KLA■ka Institute of mathematics Brno University of Technology

Each Tribonacci sequence starting with an arbitrary triple of integers is periodic modulo m for any modulus m 〉 1. For a given m, the mapping between the set S of all m^3 triples of initial values and the set of their coresponding periods define a partition of the set S. In this paper we shall investigate some basic questions related to these partitions from the point of view of enumerative combinatorics.

关键词： Tribonacci sequence modular periodicity partition formulas

用模型和模拟方法设计氨氯地平的群体药动学研究方案

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药学学报 2012年第7期47卷 941-946页

作者：左笑丛袁洪张毕奎 Chee m.ng Jeff S.BARRETT 阳国平黄志军裴奇郭韧周亚男荆宁宁 DI Wu 中南大学湘雅三医院湖南长沙410013 美国费城儿童医院临床药物治疗系应用药动学/药效学研究室 PA19104

合理的采样设计是建立可靠群体药动学模型的重要基础。应用非线性混合效应模型的群体药动学研究,是一种有效利用稀疏血样数据估算群体药动学参数的方法。本研究根据D最优化设计和贝叶斯法设计采样方案。以已报道的氨氯地平群体药动学模... 详细信息

合理的采样设计是建立可靠群体药动学模型的重要基础。应用非线性混合效应模型的群体药动学研究,是一种有效利用稀疏血样数据估算群体药动学参数的方法。本研究根据D最优化设计和贝叶斯法设计采样方案。以已报道的氨氯地平群体药动学模型为基础,根据临床研究的目的、给药方案和随访时间等设计几套采样方案,采用WinPOPT软件计算优化采样方案,用蒙特卡罗法(monte Carlo)对各优化的采样方案分别建立一套含400个患者的NONmEm数据文件,用NONmEm7.2软件模拟氨氯地平的浓度数据,然后估算其重要药动学参数(CL/F,V/F和ka),并计算其平均预测误差(mPE)和平均绝对预测误差(mAPE)。在6个采样方案中,以方案6和3对CL/F估算的准确度和精密度较优,mPE分别为0.1%和0.6%,mAPE均为0.7%。对V的估算,各采样方案间无明显差异。因此,选用氨氯地平拟合药动学参数的准确度和精密度较优,且采样点个数较少的方案3为最佳临床研究方案。本研究旨在为开展氨氯地平在肾功能损害合并高血压患者的群体药动学研究提供科学、有效的采样方法,为群体PK/PD研究提供一种优化设计临床研究方案的科学方法。

关键词：氨氯地平群体药动学模型和模拟方案设计

How does Covid-19 affect global equity markets?

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Financial Innovation 2022年第1期8卷 624-642页

作者： Eddie C.m.Hui ka Kwan Kevin Chan ZN744 Department of Building and Real EstateThe Hong Kong Polytechnic UniversityHung HomHong KongChina

This study applies OLS,panel regression and Granger causality test to investigate the impact of the Coronavirus disease 2019(Covid-19)outbreak on the global equity markets during the early stage of the *** find that the Covid-19 outbreak has a significant negative impact on the overall equity index return of the eight economies even at 0.1%significance ***,the pandemic has a more significant impact on the European countries than on the East Asian *** results have three main ***,policy makers should react fast to mitigate the impact of a ***,investors should be aware of an outbreak of disease or other risks and adjust their investments ***,the Covid-19 outbreak results in a shift of power from the west to the east.

关键词： Covid-19 Confirmed cases Panel regression Equity index

Advantageous mechanochemical synthesis of copper(Ⅰ)selenide semiconductor,characterization,and properties

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Frontiers of Chemical Science and Engineering 2022年第3期16卷 433-442页

作者： katarína Gáborová marcela Achimovičová michal Hegedüs Vladimír Girman mária kaňuchová Erika Dutková Institute of Geotechnics Slovak Academy of SciencesKošice04001Slovakia Institute of metallurgy Faculty of MaterialsMetallurgy and RecyclingTechnical UniversityKošice04201Slovakia Synthon s.r.o.Blansko67801Czech Republic Faculty of Science Pavol JozefŠafárik UniversityKošice04154Slovakia Institute of Earth Resources Faculty of MiningEcologyProcess Control and GeotechnologiesTechnical UniversityKošice04200Slovakia

Copper(I)selenide-nanocrystalline semiconductor was synthesized via one-step mechanochemical synthesis after 5 min milling in a planetary ball *** kinetics of synthesis was followed by X-ray powder diffraction analysis and specific surface area measurements of milled 2Cu/Se *** X-ray diffraction confirmed the orthorhombic crystal structure of Cu_(2)Se with the crystallite size∼25 *** surface chemical structure was studied by X-ray photoelectron spectroscopy,whereby the binding energy of the Cu 2p and Se 3d signals corresponded to Cu^(+)and Se^(2−)oxidation *** electron microscopy revealed agglomerated nanocrystals and confirmed their orthorhombic structure,as *** optical properties were studied utilizing ultraviolet-visible spectroscopy and photoluminescence *** direct bandgap energy 3.7 eV indicated a blue-shift phenomenon due to the quantum size *** type of Cu_(2)Se synthesis can be easily adapted to production dimensions using an industrial vibratory *** advantages of mechanochemical synthesis represent the potential for inexpensive,environmentally-friendly,and waste-free manufacturing of Cu_(2)Se.

关键词： Cu_(2)Se berzelianite nanocrystalline semiconductor mechanochemical synthesis planetary ball mill

Study of TiO_2 thin films on Si substrate by the photoacoustic elastic bending method

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Science China(Physics,mechanics & Astronomy) 2013年第7期56卷 1285-1293页

作者： TODOROVI Dragan m RABASOVI mihailo D mARKUSHEV Dragan D FRANKO mladen TAngAR Urka Lavreni Institute for multidisciplinary Research University of Belgrade Institute of Physics University of Belgrade Laboratory for Environmental Research University of Nova Gorica

The quantitative photoacoustic investigation of different TiO2 thin films on Si substrates is presented using the elastic bending method. Photoacoustic signal amplitude and phase spectra versus modulation frequency were measured and analyzed using different sample thicknesses. Within the proposed method particular attention is given to the analysis of optical, thermal, elastic and structural sample parameters. Considerable focus is devoted to the fitting procedure of experimental results using the two-layer sample theoretical model. Characteristics of previously developed photoacoustic apparatus are discussed, attempting to search the ideal experimental conditions which can provide a good signal-to-noise ratio and sensitivity.

关键词： photoacoustic TiO2 thin films