The construction industry needs modern construction methodology and technology to improve sustainability and production performance.Building Information Modelling(BIM)technology supports improving the quality of produ...The construction industry needs modern construction methodology and technology to improve sustainability and production performance.Building Information Modelling(BIM)technology supports improving the quality of products by reducing design and construction defects,risks to the health and safety of workers,and reduce overall project cost and delivery time.The BIM has capabilities,but it is still undiscovered and unable to exploit the full scale of its benefits in the Architectural Engineering and Construction(AEC)industry.There is a trend to adopt the BIM level 1,which is limited to 2D and only in a few cases 3D models uses in the design and construction of residential and commercial buildings,particularly in Nepal.Hence,this paper focuses on providing insight into the BIM benefits and identifies the potential barriers while adopting BIM Level 3 in Nepal.This was accomplished by developing a 4DBIM model of a multi-story residential building in Nepal and conducting the industry survey via focus group with the AEC professionals based on the developed 4DBIM model.A comprehensive literature review was conducted and presented the findings of the BIM benefits and barriers while adopting BIM.The study found that commercial and governmental projects can immediately be adopted BIM technology.It is concluded that the unavailability of skilled BIM users and the lack of proper policies for BIM adoption are key barriers in Nepal.Hence,the new policy is required to achieve and exploit the full scale of the BIM benefits and improve the project delivery in terms of quality,cost and time including the health and safety of workers and the sustainability of the AEC industry.展开更多
Sustainable business model innovation(SBMI)introduced a unique frontier in current business operations and innovation management.Despite the numerous advantages of SBMI to contemporary business strategy,most establish...Sustainable business model innovation(SBMI)introduced a unique frontier in current business operations and innovation management.Despite the numerous advantages of SBMI to contemporary business strategy,most established firms face challenges in its successful implementation.Through a systematic review process(SRP),the paper attempted to critically evaluate and analyze the previous outcome on the barriers and drivers to SBMI.The research explored 42 prior studies to identify the thematic study areas,highlight the research gaps,and outline future propositions and agendas.The research thoroughly evaluates the state-of-the-art regarding barriers and drivers to implement SBMI.The SRP approach utilized in the study sheds light on the intricacies of SBMI by highlighting six critical barriers:institutional,organizational,strategic,resource allocation,technological,and financial barriers that hinder the successful deployment of SBMI.In addition,the study’s findings indicated that organizational learning,knowledge management,dynamic capabilities resource mobilization,innovative business activities,and human resource development could be a catalyst to the successful implementation of SBMI.Furthermore,the study highlighted some critical gaps and agendas for future research on SBMI.This study contributes to the literature on business model innovation and offers a practical outlook that can facilitate firms and policymakers in developing strategies to improve their business model.展开更多
The present study focuses on the breaching process and failure of barrier dams due to overtopping. In this work, a series of centrifugal model tests is presented to examine the failure mechanisms of landslide dams. Ba...The present study focuses on the breaching process and failure of barrier dams due to overtopping. In this work, a series of centrifugal model tests is presented to examine the failure mechanisms of landslide dams. Based on the experimental results, failure process and mechanism of barrier dam due to overtopping are analyzed and further verified by simulating the experimental overtopping failure process. The results indicate that the barrier dam will develop during the entire process of overtopping in the width direction, whereas the breach will cease to develop at an early stage in the depth direction because of the large particles that accumulate on the downstream slope. Moreover, headcut erosion can be clearly observed in the first two stages of overtopping, and coarsening on the downstream slope occurs in the last stage of overtopping. Thus, the bottom part of the barrier dam can survive after dam breaching and full dam failure becomes relatively rare for a barrier dam. Furthermore, the remaining breach would be smaller than that of a homogeneous cohesive dam under the same conditions.展开更多
This article considers a Markov-dependent risk model with a constant dividend barrier. A system of integro-differential equations with boundary conditions satisfied by the expected discounted penalty function, with gi...This article considers a Markov-dependent risk model with a constant dividend barrier. A system of integro-differential equations with boundary conditions satisfied by the expected discounted penalty function, with given initial environment state, is derived and solved. Explicit formulas for the discounted penalty function are obtained when the initial surplus is zero or when all the claim amount distributions are from rational family. In two state model, numerical illustrations with exponential claim amounts are given.展开更多
The dynamic response involved in car-roadside barrier impacts is studied. Therisk of occupant injures in such accidents is investigated. An approach based on accident analysisand mathematical modeling is developed and...The dynamic response involved in car-roadside barrier impacts is studied. Therisk of occupant injures in such accidents is investigated. An approach based on accident analysisand mathematical modeling is developed and described in three steps. Firstly a study of car-roadsidebarrier impact accidents is carried out with available data to define a system including car, road,roadside barrier, and occupant. Secondly a mathematical model to simulate car-to-barrier impact isdeveloped by using multi-body program MADYMO. Finally, dynamic responses of the occupant duringimpact are simulated using a car compartment model with a HYBRID III occupant model and an inputload pulse calculated in the second step. The dynamic responses of the car are analyzed by changingimpact conditions such as impact angle and impact velocity. The injury risks of the occupants arediscussed in terms of the occupant kinematics and calculated parameters: accelerations of the head,chest, and pelvis, as well as HIC value. Verification of model with experimental data is performed.Possible counter-measures for highway vehicle traffic safety and improvement of roadside barrierdesign are presented. Research prospects in this field are also proposed.展开更多
The blood-brain barrier (BBB) forms a highly selective inter- face between blood and brain. Extensive research efforts have completely changed our view of the BBB in the last years, from a static, impermeable barrie...The blood-brain barrier (BBB) forms a highly selective inter- face between blood and brain. Extensive research efforts have completely changed our view of the BBB in the last years, from a static, impermeable barrier to a dynamic, highly regulated and specific cellular system. The BBB ultrastructurally consists of specialized brain microvascular endothelial cells (BMEC) characterized by low pinocytic activity,展开更多
Background: Preventing anterior cruciate ligament(ACL) injuries is important to avoid long-term adverse health consequences. Identifying barriers to implementation of these prevention programs is crucial to reducing t...Background: Preventing anterior cruciate ligament(ACL) injuries is important to avoid long-term adverse health consequences. Identifying barriers to implementation of these prevention programs is crucial to reducing the incidence of these injuries. Our purpose was to identify barriers of implementation for ACL injury prevention programs and suggest mechanisms for reducing the barriers through application of a SocioEcological Model(SEM).Methods: Studies investigating ACL prevention program effectiveness were searched in Medline via PubMed and the Cochrane Library, and a subsequent review of the references of the identified articles, yielded 15 articles total. Inclusion criteria encompassed prospective controlled trials, published in English, with ACL injuries as the primary outcome. Studies were independently appraised by 2 reviewers for methodological quality using the PEDro scale. Barriers to implementation were identified when reported in at least 2 separate studies. A SEM was used to suggest ways to reduce the identified barriers.Results: Five barriers were identified: motivation, time requirements, skill requirements for program facilitators, compliance, and cost. The SEM suggested ways to minimize the barriers at all levels of the model from the individual through policy levels.Conclusion: Identification of barriers to program implementation and suggesting how to reduce them through the SEM is a critical first step toward enabling ACL prevention programs to be more effective and ultimately reducing the incidence of these injuries.展开更多
A barrier option valuation model with stochastic barrier which was regarded as the main feature of the model was developed under the Hull-White interest rate model.The purpose of this study was to deal with the stocha...A barrier option valuation model with stochastic barrier which was regarded as the main feature of the model was developed under the Hull-White interest rate model.The purpose of this study was to deal with the stochastic barrier by means of partial differential equation methods and then derive the exact analytical solutions of the barrier options.Furthermore,a numerical example was given to show how to apply this model to pricing one structured product in realistic market.Therefore,this model can provide new insight for future research on structured products involving barrier options.展开更多
In this paper, various patterns of dielectric barrier glow discharge simulated by a phenomenological dynamic model are reported.The model is constructed based on the basic dynamic process of dielectric barrier glow di...In this paper, various patterns of dielectric barrier glow discharge simulated by a phenomenological dynamic model are reported.The model is constructed based on the basic dynamic process of dielectric barrier glow discharge and involves the voltage-transfer characteristic as well as the lateral inhibition effect.In simulations, different driving voltage profiles are applied to achieve one or two pulsed discharges in each half-period and the corresponding pattern evolution is investigated.The final stable patterns driven by a rectangular wave voltage organize simply as stationary striations or hexagonal lattices.The patterns driven by a multi-step wave appear to be much more complicated, with complementary striations,concentric rings and square superlattices observed.The evolutions of these patterns from the initial uniform state are described and it is found that the spreading of the inhibition effect plays a key role in these evolutions.The numerical simulations in the present work are in excellent accordance with previous experiments and fluid modeling.This dynamic model proves to be a convenient and promising approach to reproducing different pattern structures and pattern evolutions in dielectric barrier glow discharge systems.展开更多
Objective To comparatively study the toxicity of four metal-containing nanoparticles(MNPs) and their chemical counterparts to the air-blood barrier(ABB) permeability using an in vitro model.Methods ABB model, which wa...Objective To comparatively study the toxicity of four metal-containing nanoparticles(MNPs) and their chemical counterparts to the air-blood barrier(ABB) permeability using an in vitro model.Methods ABB model, which was developed via the co-culturing of A549 and pulmonary capillary endothelium, was exposed to spherical CuO-NPs(divided into CuO-40, CuO-80, and CuO-100 based on particle size), nano-Al2O3(sheet and short-rod-shaped), nano-ZnO, nano-Pb S, CuSO4, Al2(SO4)3, Zn(CH3COO)2, and Pb(NO3)2 for 60 min.Every 10 min following exposure, the cumulative cleared volume(ΔTCL) of Lucifer yellow by the model was calculated.A clearance curve was established using linear regression analysis of ΔTCL versus time.Permeability coefficient(P) was calculated based on the slope of the curve to represent the degree of change in the ABB permeability.Results The results found the increased P values of CuO-40, CuO-80, sheet, and short-rod-shaped nano-Al2O3, Al2(SO4)3, and Pb(NO3)2.Among them, small CuO-40 and CuO-80 were stronger than CuO-100 and CuSO4;no difference was observed between Al2(SO4)3 and sheet and short-rod-shaped nano-Al2O3;and nano-Pb S was slightly weaker than Pb(NO3)2.So clearly the MNPs possess diverse toxicity.Conclusion ABB permeability abnormality means pulmonary toxicity potential.More studies are warranted to understand MNPs toxicity and ultimately control the health hazards.展开更多
By solving Poisson's equation in both semiconductor and gate insulator regions in the cylindrical coordinates, an analytical model for a dual-material surrounding-gate (DMSG) metal-oxide semiconductor field-effect ...By solving Poisson's equation in both semiconductor and gate insulator regions in the cylindrical coordinates, an analytical model for a dual-material surrounding-gate (DMSG) metal-oxide semiconductor field-effect transistor (MOSFET) with a high-k gate dielectric has been developed. Using the derived model, the influences of fringing-induced barrier lowering (FIBL) on surface potential, subthreshold current, DIBL, and subthreshold swing are investigated. It is found that for the same equivalent oxide thickness, the gate insulator with high-k dielectric degrades the short-channel performance of the DMSG MOSFET. The accuracy of the analytical model is verified by the good agreement of its results with that obtained from the ISE three-dimensional numerical device simulator.展开更多
We consider the Sparre Andersen risk process in the presence of a constant dividend barrier, and propose a new expected discounted penalty function which is different from that of Gerber and Shiu. We find that iterati...We consider the Sparre Andersen risk process in the presence of a constant dividend barrier, and propose a new expected discounted penalty function which is different from that of Gerber and Shiu. We find that iteration mothed can be used to compute the values of expected discounted dividends until ruin and the new penalty function. Applying the new function and the recursion method proposed in Section 5, we obtain the arbitrary moments of discounted dividend payments until ruin.展开更多
As a kind of weak-path dependent options, barrier options are an important kind of exotic options. Because the pricing formula for pricing barrier options with discrete observations cannot avoid computing a high dimen...As a kind of weak-path dependent options, barrier options are an important kind of exotic options. Because the pricing formula for pricing barrier options with discrete observations cannot avoid computing a high dimensional integral, numerical calculation is time-consuming. In the current studies, some scholars just obtained theoretical derivation, or gave some simulation calculations. Others impose underlying assets on some strong assumptions, for example, a lot of calculations are based on the Black-Scholes model. This thesis considers Merton jump diffusion model as the basic model to derive the pricing formula of discrete double barrier option;numerical calculation method is used to approximate the continuous convolution by calculating discrete convolution. Then we compare the results of theoretical calculation with simulation results by Monte Carlo method, to verify their efficiency and accuracy. By comparing the results of degeneration constant parameter model with the results of previous models we verified the calculation method is correct indirectly. Compared with the Monte Carlo simulation method, the numerical results are stable. Even if we assume the simulation results are accurate, the time consumed by the numerical method to achieve the same accuracy is much less than the Monte Carlo simulation method.展开更多
We present the variations of electrical parameters of dielectric barrier discharge(DBD)when the DBD generator is used for the material modification,whereas the relevant physical mechanism is also elaborated.An equival...We present the variations of electrical parameters of dielectric barrier discharge(DBD)when the DBD generator is used for the material modification,whereas the relevant physical mechanism is also elaborated.An equivalent circuit model is applied for a DBD generator working in a filament discharging mode,considering the addition of epoxy resin(EP)as the plasma modified material.The electrical parameters are calculated through the circuit model.The surface conductivity,surface potential decay,trap distributions and surface charge distributions on the EP surface before and after plasma treatments were measured and calculated.It is found that the coverage area of micro-discharge channels on the EP surface is increased with the discharging time under the same applied AC voltage.The results indicate that the plasma modified material could influence the ignition of new filaments in return during the modification process.Moreover,the surface conductivity and density of shallow traps with low trap energy of the EP samples increase after the plasma treatment.The surface charge distributions indicate that the improved surface properties accelerate the movement and redistribution of charge carriers on the EP surface.The variable electrical parameters of discharge are attributed to the redistribution of deposited surface charge on the plasma modified EP sample surface.展开更多
The propagation for the model I crack in aluminum single crystal has been directly studied by in-situ TEM observation.The equation of energy barrier of the dislocation building-up and emission at the model I crack tip...The propagation for the model I crack in aluminum single crystal has been directly studied by in-situ TEM observation.The equation of energy barrier of the dislocation building-up and emission at the model I crack tip has been established by means of Peierls-Nabarro dislocation model and starting from angle of energy.By means of calculation,the critical value of spontaneous emission of the dislocations from tip of the model I crack was obtained.展开更多
A surface dielectric barrier discharge (SDBD) can discharge at atmospheric pressure and produce a large area of low-temperature plasma.An SDBD plasma reactor based on the double spiral structure is introduced in this ...A surface dielectric barrier discharge (SDBD) can discharge at atmospheric pressure and produce a large area of low-temperature plasma.An SDBD plasma reactor based on the double spiral structure is introduced in this paper.To study the discharge mechanism of SDBD,an equivalent circuit model was proposed based on the analysis of the micro-discharge process of SDBD.Matlab/Simulink is used to simulate and compare the voltage-current waves,Lissajous and discharge power with the experimental results.The consistency of the results verifies the validity of the SDBD equivalent circuit model.Maxwell software based on the finite elements method is used to analyze the electrostatic field distribution of the device,which can better explain the relationship between the discharge image and the electrostatic field distribution.The combination of equivalent circuit simulation and electrostatic field simulation can provide better guidance for optimizing a plasma generator.Finally,the device is used to treat PM2.5 and formaldehyde.The test results show that the degradation rate of PM2.5 can reach 78% after 24 min,and formaldehyde is about 31.5% after 10m in of plasma treatment.展开更多
The optimization of high power terahertz monolithic integrated circuit (TMIC) is systemically studied based on the physical model of the Schottky barrier varactor (SBV) with interface defects and tunneling effect. An ...The optimization of high power terahertz monolithic integrated circuit (TMIC) is systemically studied based on the physical model of the Schottky barrier varactor (SBV) with interface defects and tunneling effect. An ultra-thin dielectric layer is added to describe the extra tunneling effect and the damping of thermionic emission current induced by the interface defects. Power consumption of the dielectric layer results in the decrease of capacitance modulation ration (Cmax/Cmin), and thus leads to poor nonlinear C–V characteristics. The proposed Schottky metal-brim (SMB) terminal structure could improve the capacitance modulation ration by reducing the influence of the interface charge and eliminating the fringing capacitance effect. Finally, a 215 GHz tripler TMIC is fabricated based on the SMB terminal structure. The output power is above 5 mW at 210–218 GHz and the maximum could exceed 10 mW at 216 GHz, which could be widely used in terahertz imaging, radiometers, and so on. This paper also provides theoretical support for the SMB structure to optimize the TMIC performance.展开更多
Alzheimer's disease(AD)is characterized by complex etiology,long-lasting pathogenesis,and celltype-specific alterations.Currently,there is no cure for AD,emphasizing the urgent need for a comprehensive understandi...Alzheimer's disease(AD)is characterized by complex etiology,long-lasting pathogenesis,and celltype-specific alterations.Currently,there is no cure for AD,emphasizing the urgent need for a comprehensive understanding of cell-specific pathology.Astrocytes,principal homeostatic cells of the central nervous system,are key players in the pathogenesis of neurodegenerative diseases,including AD.Cellular models greatly facilitate the investigation of cell-specific pathological alterations and the dissection of molecular mechanisms and pathways.Tumor-derived and immortalized astrocytic cell lines,alongside the emerging technology of adult induced pluripotent stem cells,are widely used to study cellular dysfunction in AD.Surprisingly,no stable cell lines were available from genetic mouse AD models.Recently,we established immortalized hippocampal astroglial cell lines from amyloid-βprecursor protein/presenilin-1/Tau triple-transgenic(3xTg)-AD mice(denominated as wild type(WT)-and 3Tg-iAstro cells)using retrovirus-mediated transduction of simian virus 40 large T-antigen and propagation without clonal selection,thereby maintaining natural heterogeneity of primary cultures.Several groups have successfully used 3Tg-iAstro cells for single-cell and omics approaches to study astrocytic AD-related alterations of calcium signaling,mitochondrial dysfunctions,disproteostasis,altered homeostatic and signaling support to neurons,and blood-brain barrier models.Here we provide a comparative overview of the most used models to study astrocytes in vitro,such as primary culture,tumor-derived cell lines,immortalized astroglial cell lines,and induced pluripotent stem cell-derived astrocytes.We conclude that immortalized WT-and 3Tg-iAstro cells provide a noncompetitive but complementary,low-cost,easy-to-handle,and versatile cellular model for dissection of astrocyte-specific AD-related alterations and preclinical drug discovery.展开更多
The Technical Barriers to Trade (TBT) is an important problem faced to the export of China. Based on the number differences of TBT notifications between countries, we propose the concept and computational method of ...The Technical Barriers to Trade (TBT) is an important problem faced to the export of China. Based on the number differences of TBT notifications between countries, we propose the concept and computational method of the technical barrier coefficient. By means of price-production and price-demand functions, a trade model with a developed country and a developing country is designed. The available trade policies such as technical barriers, tariffs and export subsidies are simulated and analyzed. According to the simulation results, several trade strategies to come over technical barriers are suggested. These suggestions were provided to several export enterprises for their export strategy design.展开更多
There is an urgent and tremendous need for human dis- ease models in drug development in order to improve pre- clinical predictability. In the case of brain disorders drugs have to cross the blood-brain barrier (BBB...There is an urgent and tremendous need for human dis- ease models in drug development in order to improve pre- clinical predictability. In the case of brain disorders drugs have to cross the blood-brain barrier (BBB) to enter the central nervous system (CNS). It was estimated that more than 95% of the drugs cannot cross the BBB.展开更多
文摘The construction industry needs modern construction methodology and technology to improve sustainability and production performance.Building Information Modelling(BIM)technology supports improving the quality of products by reducing design and construction defects,risks to the health and safety of workers,and reduce overall project cost and delivery time.The BIM has capabilities,but it is still undiscovered and unable to exploit the full scale of its benefits in the Architectural Engineering and Construction(AEC)industry.There is a trend to adopt the BIM level 1,which is limited to 2D and only in a few cases 3D models uses in the design and construction of residential and commercial buildings,particularly in Nepal.Hence,this paper focuses on providing insight into the BIM benefits and identifies the potential barriers while adopting BIM Level 3 in Nepal.This was accomplished by developing a 4DBIM model of a multi-story residential building in Nepal and conducting the industry survey via focus group with the AEC professionals based on the developed 4DBIM model.A comprehensive literature review was conducted and presented the findings of the BIM benefits and barriers while adopting BIM.The study found that commercial and governmental projects can immediately be adopted BIM technology.It is concluded that the unavailability of skilled BIM users and the lack of proper policies for BIM adoption are key barriers in Nepal.Hence,the new policy is required to achieve and exploit the full scale of the BIM benefits and improve the project delivery in terms of quality,cost and time including the health and safety of workers and the sustainability of the AEC industry.
文摘Sustainable business model innovation(SBMI)introduced a unique frontier in current business operations and innovation management.Despite the numerous advantages of SBMI to contemporary business strategy,most established firms face challenges in its successful implementation.Through a systematic review process(SRP),the paper attempted to critically evaluate and analyze the previous outcome on the barriers and drivers to SBMI.The research explored 42 prior studies to identify the thematic study areas,highlight the research gaps,and outline future propositions and agendas.The research thoroughly evaluates the state-of-the-art regarding barriers and drivers to implement SBMI.The SRP approach utilized in the study sheds light on the intricacies of SBMI by highlighting six critical barriers:institutional,organizational,strategic,resource allocation,technological,and financial barriers that hinder the successful deployment of SBMI.In addition,the study’s findings indicated that organizational learning,knowledge management,dynamic capabilities resource mobilization,innovative business activities,and human resource development could be a catalyst to the successful implementation of SBMI.Furthermore,the study highlighted some critical gaps and agendas for future research on SBMI.This study contributes to the literature on business model innovation and offers a practical outlook that can facilitate firms and policymakers in developing strategies to improve their business model.
基金financial support from the National Natural Science Foundation of China (Grant No. 51709025)the Chongqing Science and Technology Commission of China (Grant No. cstc2018jcyjAX0084, cstc2018jcyjAX0391 and cstc2016jcyjA0551)Open Research Fund of Key Laboratory of Failure Mechanism and Safety Control Techniques of Earth-Rock Dam of the Ministry of Water Resources (Grant No. YK319006)
文摘The present study focuses on the breaching process and failure of barrier dams due to overtopping. In this work, a series of centrifugal model tests is presented to examine the failure mechanisms of landslide dams. Based on the experimental results, failure process and mechanism of barrier dam due to overtopping are analyzed and further verified by simulating the experimental overtopping failure process. The results indicate that the barrier dam will develop during the entire process of overtopping in the width direction, whereas the breach will cease to develop at an early stage in the depth direction because of the large particles that accumulate on the downstream slope. Moreover, headcut erosion can be clearly observed in the first two stages of overtopping, and coarsening on the downstream slope occurs in the last stage of overtopping. Thus, the bottom part of the barrier dam can survive after dam breaching and full dam failure becomes relatively rare for a barrier dam. Furthermore, the remaining breach would be smaller than that of a homogeneous cohesive dam under the same conditions.
基金supported in part by Hubei Normal University Post-graduate Foundation(2007D59 and 2007D60)the Science and Technology foundation of Hubei(D20092207)the National Natural Science Foundation of China(10671149)
文摘This article considers a Markov-dependent risk model with a constant dividend barrier. A system of integro-differential equations with boundary conditions satisfied by the expected discounted penalty function, with given initial environment state, is derived and solved. Explicit formulas for the discounted penalty function are obtained when the initial surplus is zero or when all the claim amount distributions are from rational family. In two state model, numerical illustrations with exponential claim amounts are given.
文摘The dynamic response involved in car-roadside barrier impacts is studied. Therisk of occupant injures in such accidents is investigated. An approach based on accident analysisand mathematical modeling is developed and described in three steps. Firstly a study of car-roadsidebarrier impact accidents is carried out with available data to define a system including car, road,roadside barrier, and occupant. Secondly a mathematical model to simulate car-to-barrier impact isdeveloped by using multi-body program MADYMO. Finally, dynamic responses of the occupant duringimpact are simulated using a car compartment model with a HYBRID III occupant model and an inputload pulse calculated in the second step. The dynamic responses of the car are analyzed by changingimpact conditions such as impact angle and impact velocity. The injury risks of the occupants arediscussed in terms of the occupant kinematics and calculated parameters: accelerations of the head,chest, and pelvis, as well as HIC value. Verification of model with experimental data is performed.Possible counter-measures for highway vehicle traffic safety and improvement of roadside barrierdesign are presented. Research prospects in this field are also proposed.
基金supported by Innovative Medizinische Forschung(I-RU211405 to TR and I-BI111316 to SB and SGM)by the Deutsche Forschungsgemeinschaft(SFB 1009)by the Genzyme Neuroimmunology Fellowship Program(to TR)
文摘The blood-brain barrier (BBB) forms a highly selective inter- face between blood and brain. Extensive research efforts have completely changed our view of the BBB in the last years, from a static, impermeable barrier to a dynamic, highly regulated and specific cellular system. The BBB ultrastructurally consists of specialized brain microvascular endothelial cells (BMEC) characterized by low pinocytic activity,
文摘Background: Preventing anterior cruciate ligament(ACL) injuries is important to avoid long-term adverse health consequences. Identifying barriers to implementation of these prevention programs is crucial to reducing the incidence of these injuries. Our purpose was to identify barriers of implementation for ACL injury prevention programs and suggest mechanisms for reducing the barriers through application of a SocioEcological Model(SEM).Methods: Studies investigating ACL prevention program effectiveness were searched in Medline via PubMed and the Cochrane Library, and a subsequent review of the references of the identified articles, yielded 15 articles total. Inclusion criteria encompassed prospective controlled trials, published in English, with ACL injuries as the primary outcome. Studies were independently appraised by 2 reviewers for methodological quality using the PEDro scale. Barriers to implementation were identified when reported in at least 2 separate studies. A SEM was used to suggest ways to reduce the identified barriers.Results: Five barriers were identified: motivation, time requirements, skill requirements for program facilitators, compliance, and cost. The SEM suggested ways to minimize the barriers at all levels of the model from the individual through policy levels.Conclusion: Identification of barriers to program implementation and suggesting how to reduce them through the SEM is a critical first step toward enabling ACL prevention programs to be more effective and ultimately reducing the incidence of these injuries.
基金National Natural Science Foundations of China(Nos.11471175,11171221)
文摘A barrier option valuation model with stochastic barrier which was regarded as the main feature of the model was developed under the Hull-White interest rate model.The purpose of this study was to deal with the stochastic barrier by means of partial differential equation methods and then derive the exact analytical solutions of the barrier options.Furthermore,a numerical example was given to show how to apply this model to pricing one structured product in realistic market.Therefore,this model can provide new insight for future research on structured products involving barrier options.
基金supported by National Natural Science Foundation of China (Nos.11875238, 11305156)the Science Challenge Project (No.TZ2016001)
文摘In this paper, various patterns of dielectric barrier glow discharge simulated by a phenomenological dynamic model are reported.The model is constructed based on the basic dynamic process of dielectric barrier glow discharge and involves the voltage-transfer characteristic as well as the lateral inhibition effect.In simulations, different driving voltage profiles are applied to achieve one or two pulsed discharges in each half-period and the corresponding pattern evolution is investigated.The final stable patterns driven by a rectangular wave voltage organize simply as stationary striations or hexagonal lattices.The patterns driven by a multi-step wave appear to be much more complicated, with complementary striations,concentric rings and square superlattices observed.The evolutions of these patterns from the initial uniform state are described and it is found that the spreading of the inhibition effect plays a key role in these evolutions.The numerical simulations in the present work are in excellent accordance with previous experiments and fluid modeling.This dynamic model proves to be a convenient and promising approach to reproducing different pattern structures and pattern evolutions in dielectric barrier glow discharge systems.
基金sponsored by the National Natural Science Foundation of China [No.81372949]the Young Scholar Scientific Research Foundation of China CDC [No.2016A206]
文摘Objective To comparatively study the toxicity of four metal-containing nanoparticles(MNPs) and their chemical counterparts to the air-blood barrier(ABB) permeability using an in vitro model.Methods ABB model, which was developed via the co-culturing of A549 and pulmonary capillary endothelium, was exposed to spherical CuO-NPs(divided into CuO-40, CuO-80, and CuO-100 based on particle size), nano-Al2O3(sheet and short-rod-shaped), nano-ZnO, nano-Pb S, CuSO4, Al2(SO4)3, Zn(CH3COO)2, and Pb(NO3)2 for 60 min.Every 10 min following exposure, the cumulative cleared volume(ΔTCL) of Lucifer yellow by the model was calculated.A clearance curve was established using linear regression analysis of ΔTCL versus time.Permeability coefficient(P) was calculated based on the slope of the curve to represent the degree of change in the ABB permeability.Results The results found the increased P values of CuO-40, CuO-80, sheet, and short-rod-shaped nano-Al2O3, Al2(SO4)3, and Pb(NO3)2.Among them, small CuO-40 and CuO-80 were stronger than CuO-100 and CuSO4;no difference was observed between Al2(SO4)3 and sheet and short-rod-shaped nano-Al2O3;and nano-Pb S was slightly weaker than Pb(NO3)2.So clearly the MNPs possess diverse toxicity.Conclusion ABB permeability abnormality means pulmonary toxicity potential.More studies are warranted to understand MNPs toxicity and ultimately control the health hazards.
基金supported by the Fundamental Research Funds for the Central Universities (Grant No. K50511250001)the National Natural Science Foundation of China (Grant No. 61076101)
文摘By solving Poisson's equation in both semiconductor and gate insulator regions in the cylindrical coordinates, an analytical model for a dual-material surrounding-gate (DMSG) metal-oxide semiconductor field-effect transistor (MOSFET) with a high-k gate dielectric has been developed. Using the derived model, the influences of fringing-induced barrier lowering (FIBL) on surface potential, subthreshold current, DIBL, and subthreshold swing are investigated. It is found that for the same equivalent oxide thickness, the gate insulator with high-k dielectric degrades the short-channel performance of the DMSG MOSFET. The accuracy of the analytical model is verified by the good agreement of its results with that obtained from the ISE three-dimensional numerical device simulator.
文摘We consider the Sparre Andersen risk process in the presence of a constant dividend barrier, and propose a new expected discounted penalty function which is different from that of Gerber and Shiu. We find that iteration mothed can be used to compute the values of expected discounted dividends until ruin and the new penalty function. Applying the new function and the recursion method proposed in Section 5, we obtain the arbitrary moments of discounted dividend payments until ruin.
文摘As a kind of weak-path dependent options, barrier options are an important kind of exotic options. Because the pricing formula for pricing barrier options with discrete observations cannot avoid computing a high dimensional integral, numerical calculation is time-consuming. In the current studies, some scholars just obtained theoretical derivation, or gave some simulation calculations. Others impose underlying assets on some strong assumptions, for example, a lot of calculations are based on the Black-Scholes model. This thesis considers Merton jump diffusion model as the basic model to derive the pricing formula of discrete double barrier option;numerical calculation method is used to approximate the continuous convolution by calculating discrete convolution. Then we compare the results of theoretical calculation with simulation results by Monte Carlo method, to verify their efficiency and accuracy. By comparing the results of degeneration constant parameter model with the results of previous models we verified the calculation method is correct indirectly. Compared with the Monte Carlo simulation method, the numerical results are stable. Even if we assume the simulation results are accurate, the time consumed by the numerical method to achieve the same accuracy is much less than the Monte Carlo simulation method.
基金Project supported by the National Key R&D Program of China(Grant No.2018YFB0904400)the National Natural Science Foundation of China(Grant No.51977187)+3 种基金the“Science and Technology Innovation 2025”Key Project of Ningbo City,China(Grant No.2018B10019)the Natural Science Foundation of Zhejiang Province,China(Grant No.LY18E070003)the State Key Laboratory of HVDC,Electric Power Research Institute,China Southern Power Grid(Grant No.SKLHVDC-2019-KF-18)the Fundamental Research Funds for the Central Universities,China(Grant No.2018QNA4017).
文摘We present the variations of electrical parameters of dielectric barrier discharge(DBD)when the DBD generator is used for the material modification,whereas the relevant physical mechanism is also elaborated.An equivalent circuit model is applied for a DBD generator working in a filament discharging mode,considering the addition of epoxy resin(EP)as the plasma modified material.The electrical parameters are calculated through the circuit model.The surface conductivity,surface potential decay,trap distributions and surface charge distributions on the EP surface before and after plasma treatments were measured and calculated.It is found that the coverage area of micro-discharge channels on the EP surface is increased with the discharging time under the same applied AC voltage.The results indicate that the plasma modified material could influence the ignition of new filaments in return during the modification process.Moreover,the surface conductivity and density of shallow traps with low trap energy of the EP samples increase after the plasma treatment.The surface charge distributions indicate that the improved surface properties accelerate the movement and redistribution of charge carriers on the EP surface.The variable electrical parameters of discharge are attributed to the redistribution of deposited surface charge on the plasma modified EP sample surface.
文摘The propagation for the model I crack in aluminum single crystal has been directly studied by in-situ TEM observation.The equation of energy barrier of the dislocation building-up and emission at the model I crack tip has been established by means of Peierls-Nabarro dislocation model and starting from angle of energy.By means of calculation,the critical value of spontaneous emission of the dislocations from tip of the model I crack was obtained.
基金National Natural Science Foundation of China (No. 11575066).
文摘A surface dielectric barrier discharge (SDBD) can discharge at atmospheric pressure and produce a large area of low-temperature plasma.An SDBD plasma reactor based on the double spiral structure is introduced in this paper.To study the discharge mechanism of SDBD,an equivalent circuit model was proposed based on the analysis of the micro-discharge process of SDBD.Matlab/Simulink is used to simulate and compare the voltage-current waves,Lissajous and discharge power with the experimental results.The consistency of the results verifies the validity of the SDBD equivalent circuit model.Maxwell software based on the finite elements method is used to analyze the electrostatic field distribution of the device,which can better explain the relationship between the discharge image and the electrostatic field distribution.The combination of equivalent circuit simulation and electrostatic field simulation can provide better guidance for optimizing a plasma generator.Finally,the device is used to treat PM2.5 and formaldehyde.The test results show that the degradation rate of PM2.5 can reach 78% after 24 min,and formaldehyde is about 31.5% after 10m in of plasma treatment.
文摘The optimization of high power terahertz monolithic integrated circuit (TMIC) is systemically studied based on the physical model of the Schottky barrier varactor (SBV) with interface defects and tunneling effect. An ultra-thin dielectric layer is added to describe the extra tunneling effect and the damping of thermionic emission current induced by the interface defects. Power consumption of the dielectric layer results in the decrease of capacitance modulation ration (Cmax/Cmin), and thus leads to poor nonlinear C–V characteristics. The proposed Schottky metal-brim (SMB) terminal structure could improve the capacitance modulation ration by reducing the influence of the interface charge and eliminating the fringing capacitance effect. Finally, a 215 GHz tripler TMIC is fabricated based on the SMB terminal structure. The output power is above 5 mW at 210–218 GHz and the maximum could exceed 10 mW at 216 GHz, which could be widely used in terahertz imaging, radiometers, and so on. This paper also provides theoretical support for the SMB structure to optimize the TMIC performance.
基金supported by fellowship to a grant from CRT Foundation,No.1393-2017(to LT)grants from the Fondazione Cariplo,Nos.2013-0795(to AAG),2014-1094(to DL)grants from The Universitàdel Piemonte Orientale,Nos.FAR-2016(to DL),FAR-2019(to DL)。
文摘Alzheimer's disease(AD)is characterized by complex etiology,long-lasting pathogenesis,and celltype-specific alterations.Currently,there is no cure for AD,emphasizing the urgent need for a comprehensive understanding of cell-specific pathology.Astrocytes,principal homeostatic cells of the central nervous system,are key players in the pathogenesis of neurodegenerative diseases,including AD.Cellular models greatly facilitate the investigation of cell-specific pathological alterations and the dissection of molecular mechanisms and pathways.Tumor-derived and immortalized astrocytic cell lines,alongside the emerging technology of adult induced pluripotent stem cells,are widely used to study cellular dysfunction in AD.Surprisingly,no stable cell lines were available from genetic mouse AD models.Recently,we established immortalized hippocampal astroglial cell lines from amyloid-βprecursor protein/presenilin-1/Tau triple-transgenic(3xTg)-AD mice(denominated as wild type(WT)-and 3Tg-iAstro cells)using retrovirus-mediated transduction of simian virus 40 large T-antigen and propagation without clonal selection,thereby maintaining natural heterogeneity of primary cultures.Several groups have successfully used 3Tg-iAstro cells for single-cell and omics approaches to study astrocytic AD-related alterations of calcium signaling,mitochondrial dysfunctions,disproteostasis,altered homeostatic and signaling support to neurons,and blood-brain barrier models.Here we provide a comparative overview of the most used models to study astrocytes in vitro,such as primary culture,tumor-derived cell lines,immortalized astroglial cell lines,and induced pluripotent stem cell-derived astrocytes.We conclude that immortalized WT-and 3Tg-iAstro cells provide a noncompetitive but complementary,low-cost,easy-to-handle,and versatile cellular model for dissection of astrocyte-specific AD-related alterations and preclinical drug discovery.
基金This work is supported by National Nature Science Foundation (No. 70771021, No. 60821063).
文摘The Technical Barriers to Trade (TBT) is an important problem faced to the export of China. Based on the number differences of TBT notifications between countries, we propose the concept and computational method of the technical barrier coefficient. By means of price-production and price-demand functions, a trade model with a developed country and a developing country is designed. The available trade policies such as technical barriers, tariffs and export subsidies are simulated and analyzed. According to the simulation results, several trade strategies to come over technical barriers are suggested. These suggestions were provided to several export enterprises for their export strategy design.
基金supported by the SET foundation(Stiftung zur Forderung der Erforschung von Ersatz-und Erganzungsmethoden zur Einschrankung von Tierversuchen)project 060 to Winfried Neuhaus and Marco Metzger
文摘There is an urgent and tremendous need for human dis- ease models in drug development in order to improve pre- clinical predictability. In the case of brain disorders drugs have to cross the blood-brain barrier (BBB) to enter the central nervous system (CNS). It was estimated that more than 95% of the drugs cannot cross the BBB.