Blood-brain barrier modeling: challenges and perspectives

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,

Study on the Continuous Transition From PTC Effect to GBBL Capacitor of Semiconducting BaTiO_3 Ceramics——Grain Boundary Barrier Model

The Daniels’ barium vacancy layer model of semiconducting BaTiO3 ceramics is analyzed.A grain boundary barrier model with both acceptor states of grain boundary and barium vacancy diffusion layers for the transition from PTC effect to grain boundary barrier layer (GBBL) capacitor is proposed.The proposed model solves the problem occurring in Daniels’ model and makes it possible to calculate physical properties of semiconducting BaTiO3 ceramics and relevant devices.

MODELING OF OCCUPANT DYNAMIC RESPONSE TO CAR-BARRIERS CRASH ON HIGHWAY

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.

ON THE EXPECTED DISCOUNTED PENALTY FUNCTION IN A MARKOV-DEPENDENT RISK MODEL WITH CONSTANT DIVIDEND BARRIER

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.

Centrifugal model tests and numerical simulations for barrier dam break due to overtopping

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.

DISLOCATION EMISSION AND EQUATION OF ENERGY BARRIERS AT 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.

Comparative Toxicity of Nanomaterials to Air-blood Barrier Permeability Using an In Vitro Model

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.

Analytical model including the fringing-induced barrier lowering effect for a dual-material surrounding-gate MOSFET with a high-κ gate dielectric

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.

Pricing Stochastic Barrier Options under Hull-White Interest Rate Model

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.

Human induced pluripotent stem cell based in vitro models of the blood-brain barrier： the future standard？

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.

Various patterns in dielectric barrier glow discharges simulated by a dynamic model

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.

Numerical Methods for Discrete Double Barrier Option Pricing Based on Merton Jump Diffusion Model

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.

Applying the Socio-Ecological Model to barriers to implementation of ACL injury prevention programs: A systematic review

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.

Moments of Discounted Dividend Payments in the Sparre Andersen Model with a Constant Dividend Barrier

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.

Research on the temperature field of a partially freezing sand barrier with groundwater seepage

To study the distribution characteristics and variation regularity of the temperature field during the process of seepage freezing,a simulated-freezing test with seepage of Xuzhou sand was completed by using a model test developed in-house equipment.By means of three group freezing tests with different seepage velocities,we discovered the phenomenon of the asymmetry of the temperature field under the influence of seepage.The temperature upstream was obviously higher than that downstream.The temperature gradient upstream was also steeper than that downstream.With a higher seepage velocity,the asymmetry of the temperature field is more pronounced.The asymmetry for the interface temperature profile is more strongly manifest than for the main surface temperature profile.The cryogenic barrier section is somewhat"heartshaped".With the increasing velocity of the seepage flow,the cooling rate of the soil decreases.It takes much time to reach the equilibrium state of the soil mass.In our study,seepage flow velocities of 0 m/d,7.5 m/d,and 15 m/d showed the soilcooling rate of 4.35°C/h,4.96°C/h,and 1.72°C/h,respectively.

Switching mechanism for TiO_2 memristor and quantitative analysis of exponential model parameters

The memristor, as the fourth basic circuit element, has drawn worldwide attention since its physical implementation was released by HP Labs in 2008. However, at the nano-scale, there are many difficulties for memristor physical realization. So a better understanding and analysis of a good model will help us to study the characteristics of a memristor. In this paper, we analyze a possible mechanism for the switching behavior of a memristor with a Pt/TiO2/Pt structure, and explain the changes of electronic barrier at the interface of Pt/TiO2. Then, a quantitative analysis about each parameter in the exponential model of memristor is conducted based on the calculation results. The analysis results are validated by simulation results. The efforts made in this paper will provide researchers with theoretical guidance on choosing appropriate values for(α, β, χ, γ) in this exponential model.

Empirical Analysis on the Impacts of Technical Barrier to Trade on Chinese Agro-products Export

In view of the impacts on Chinese agro-products export caused by various technical barriers to trade,the academic circles analyzed them from the costs and quantity of exported agro-products.On the basis of the status quo of Chinese agro-products,the gravity model is introduced to analyze the impacts on Chinese agro-product export caused by technical barriers to trade.The results show that as long as the quality of Chinese agro-products can achieve the standard set by developed countries,for one thing,the health of Chinese consumers can be ensured,for another thing,the export of Chinese agro-products will be more smooth,which can provide reference for our government to make decisions and solve trade dispute.

Initial Error-induced Optimal Perturbations in ENSO Predictions, as Derived from an Intermediate Coupled Model

The initial errors constitute one of the main limiting factors in the ability to predict the E1 Nino-Southem Oscillation （ENSO） in ocean-atmosphere coupled models. The conditional nonlinear optimal perturbation （CNOP） approach was em- ployed to study the largest initial error growth in the E1 Nino predictions of an intermediate coupled model （ICM）. The optimal initial errors （as represented by CNOPs） in sea surface temperature anomalies （SSTAs） and sea level anomalies （SLAs） were obtained with seasonal variation. The CNOP-induced perturbations, which tend to evolve into the La Nifia mode, were found to have the same dynamics as ENSO itself. This indicates that, if CNOP-type errors are present in the initial conditions used to make a prediction of E1 Nino, the E1 Nino event tends to be under-predicted. In particular, compared with other seasonal CNOPs, the CNOPs in winter can induce the largest error growth, which gives rise to an ENSO amplitude that is hardly ever predicted accurately. Additionally, it was found that the CNOP-induced perturbations exhibit a strong spring predictability barrier （SPB） phenomenon for ENSO prediction. These results offer a way to enhance ICM prediction skill and, particularly, weaken the SPB phenomenon by filtering the CNOP-type errors in the initial state. The characteristic distributions of the CNOPs derived from the ICM also provide useful information for targeted observations through data assimilation. Given the fact that the derived CNOPs are season-dependent, it is suggested that seasonally varying targeted observations should be implemented to accurately predict ENSO events.

Autoantibodies and an immune-based rat model of inflammatory bowel disease

The exact causes of inflammatory bowel disease(IBD)are not yet fully defined.From a vast body of literature,we know that the immune response has long been involved in the pathogenesis of IBD,including both ulcerative colitis and Crohn’s disease.A variety of specific alterations can lead to immune activation and inflammation directed to the colon,as revealed by some animal models.Current research has focused on the role of antibodies in downstream events and mechanisms of autoimmunity and inflammation.It is not well known whether the production of antibodies is a serologic consequence of IBD,or if it is a result of barrier dysfunction induced by inflammation.Here,we present a new hypothesis to distinguish the complex links between genetic susceptibility,barrier dysfunction,commensal and pathologic microbial factors and inflammatory response(especially autoantibodies)in the pathogenesis of IBD.To ascertain the hypothesis,we developed a pilot model with the concept of the presence of antibodies against enteric bacterial antigens in IBD.Results confirmed our hypothesis.Our hypothesis suggests the possibility of subcutaneous vaccination of animals with administration of all or specific enteric bacterial antigens.

Compact High-Velocity Atmospheric Pressure Dielectric Barrier Plasma Jet in Ambient Air

In this paper,a non-thermal atmospheric pressure plasma jet at high streaming velocity operating with ambient air is highlighted.In the present technological approach,the employment of air poses a significant challenge.The high oxygen concentration in air results in a reduced concentration of reactive species in combination with a short species lifetime.The plasma jet assembly presented here contains a special dielectric barrier with a high secondary emission coefficient.In this way,the electron density and in turn the density of reactive species is increased.In addition,the plasma jet assembly is equipped with a short electrode.This leads to a higher voltage across the discharge gap and in turn to an increased density of reactive plasma species.The plasma jet is formed within and emitted by a small conical nozzle.A high-speed gas flow with gas velocity of 340 m/s was achieved at the end of the nozzle.In the jet the concentration of toxic and unwanted neutral plasma species like O3 or NOx is significantly reduced because of the shorter residence time within the plasma.The range of short-lived active plasma species is in turn considerably enhanced.The jet efficiency and action range measured through the oxidation of a test surface were determined by measuring the increase of surface tension of a polypropylene substrate via contact angle measurements after plasma treatment.Numerical modeling of the plasma plume indicates that oxygen atoms are in fact the main active species in the plasma plume.