Airflow in a Multiscale Subject-Specific Breathing Human Lung Model

The airflow in a subject-specific breathing human lung is simulated with a multiscale computational fluid dynamics (CFD) lung model. The three-dimensional (3D) airway geometry beginning from the mouth to about 7 generations of airways is reconstructed from the multi-detector row computed tomography (MDCT) image at the total lung capacity (TLC). Along with the segmented lobe surfaces, we can build an anatomically-consistent one-dimensional (1D) airway tree spanning over more than 20 generations down to the terminal bronchioles, which is specific to the CT resolved airways and lobes (J Biomech 43(11): 2159-2163, 2010). We then register two lung images at TLC and the functional residual capacity (FRC) to specify subject-specific CFD flow boundary conditions and deform the airway surface mesh for a breathing lung simulation (J Comput Phys 244:168-192, 2013). The 1D airway tree bridges the 3D CT-resolved airways and the registration-derived regional ventilation in the lung parenchyma, thus a multiscale model. Large eddy simulation (LES) is applied to simulate airflow in a breathing lung (Phys Fluids 21:101901, 2009). In this fluid dynamics video, we present the distributions of velocity, pressure, vortical structure, and wall shear stress in a breathing lung model of a normal human subject with a tidal volume of 500 ml and a period of 4.8 s. On exhalation, air streams from child branches merge in the parent branch, inducing oscillatory jets and elongated vortical tubes. On inhalation, the glottal constriction induces turbulent laryngeal jet. The sites where high wall shear stress tends to occur on the airway surface are identified for future investigation of mechanotransduction.Comment: This submission is part of the APS DFD Gallery of Fluid Motio

Inducing optimal service capacities via performance-based allocation of demand in a queueing system with multiple servers

Theme: Soft Computing Techniques for Advanced Manufacturing and Service SystemsIn this paper, we study the use of performance-based allocation of demand in a multiple-server queueing system. The same problem with two servers have been studied in the literature. Specifically, it has been proposed and proved that the linear allocation and mixed threshold allocation policies are, respectively, the optimal state-independent and state-dependent allocation policy in the two-server case. The multiple-server linear allocation has also been shown to be the optimal state-independent policy with multiple servers. In our study, we focus on the use of a multiple-server mixed threshold allocation policy to replicate the demand allocation of a given state-independent policy to achieve a symmetric equilibrium with lower expected sojourn time. Our results indicate that, for any given multiple-server state-independent policy that prohibits server overloading, there exists a multiple-server mixed threshold policy that gives the same demand allocation and thus have the same Nash equilibrium (if any). Moreover, such a policy can be designed so that the expected sojourn time at a symmetric equilibrium is minimized. Therefore, our results concur with previous two-server results and affirm that a trade-off between incentives and efficiency need not exist in the case of multiple servers.published_or_final_versionThe 40th International Conference on Computers and Industrial Engineering, (CIE 2010), Hyogo, Japan, 25-28 July 2010. In Proceedings of the International Conference on Computers & Industrial Engineering, 2010, p. 1-

Quantity discount contract for supply chain coordination with false failure returns

Consumer return attracts more and more academic attention due to its rapidly expanding size, and a large portion of it falls into the category of false failure return, which refers to return without functional defect. In this paper, we exclusively consider profit results from exerting costly effort to reduce false failure returns in a reverse supply chain consisting of a retailer and a supplier. The supply chain as a whole has strong incentive to reduce false failure returns because it can avoid much reprocessing cost associated. But typically, retailers enjoy a full credit provided by suppliers in case of returns, and hence they may not have sufficient incentives to exert enough effort for supply chain profit maximization. In some scenarios they may even have the motivation to actually encourage such returns. We suggest using a coordination contract to resolve such profit conflicts. The contract we propose is a quantity discount contract specifying a payment to the retailer with an amount exponentially decreasing in the number of false failure returns. We give explicit forms of such contracts given different assumptions about distribution of the number of returns and we also prove that such contract is capable of increasing both retailer's and supplier's profit simultaneously. Besides, when the contract is used together with other forward supply chain coordination contracts in a closed-loop chain, it is shown that it can act to deter retailer's potential incentive to encourage false failure returns. Moreover, some modifications of the contract may lead to easy allocation of incremental profit within the supply chain. © 2010 IEEE.published_or_final_versionThe 6th International Conference on Natural Computation (ICNC 2010), Yantai, Shandong, China, 10-12 August 2010. In Proceedings of the International Conference on Natural Computation, 2010, v. 8, p. 4450-445

Minimizing equilibrium expected sojourn time via performance-based mixed threshold demand allocation in a multiple-server queueing environment

We study the optimal demand allocation policies to induce high service capacity and achieve minimum expected sojourn times in equilibrium in a queueing system with multiple strategic servers. We propose the mixed threshold allocation policy as an optimal state-dependent policy that induces optimal service capacity from strategic servers. Compensation to the server can be paid at customer allocation or upon job completion. Our study focuses on the use of a multiple-server mixed threshold allocation policy to replicate the demand of a given state-independent policy to achieve a symmetric equilibrium with lower expected sojourn time. The results indicate that, under both payment schemes, for any given multiple-server state-independent policy, there exists a multiple-server threshold policy that produces identical demand allocation and Nash equilibrium (if any). Moreover, the policy can be designed to minimize the expected sojourn time at a symmetric equilibrium. Further-more, under the payment-at-allocation scheme, our results, combining with existing results on the optimality of the multiple-server linear allocation policy, show that the mixed threshold policy can achieve the maximum feasible service capacity and thus the minimum feasible equilibrium expected sojourn time. Hence, our results agree with previous two-server results and affirm that a trade-off between incentives and efficiency need not exist in the case of multiple servers.published_or_final_versio

Incentive effects of common and separate queues with multiple servers: The principal-agent perspective

A two-server service network has been studied by Gilbert and Weng [13] fromthe principal-agent perspective. In the model, services are rendered by twoindependent facilities coordinated by an agency. The agency must devise astrategy to allocate customers to the facilities and determine the compensation.A common queue allocation scheme and separate queue allocation scheme are thencompared. It has been shown that the separate queue system gives morecompetition incentives to the independent facilities and induces a higherservice capacity. The main aim of this paper is to extend the results of thetwo-server queueing model to the case of multiple-server queueing model. Ouranalysis shows that in the case of multiple servers the separate queueallocation scheme creates more competition incentives for servers to increasetheir service capacities. In particular, when there are not severe diseconomiesassociated with increasing service capacity, the separate queue allocationscheme gives a lower expected sojourn time in equilibrium. © 2009 IEEE.published_or_final_versionProceedings of the 39th International Conference on Computers and Industrial Engineering (CIE39), Troyes, France, 6-8 July 2009, p. 1249-125

On improving incentive in a supply chain: Wholesale price contract vs quantity dependent contract

Theme: Soft Computing Techniques for Advanced Manufacturing and Service SystemsIn this paper, we first study the performance of a supply chain consisting of one retailer and one supplier. The supplier sets the price scheme of some goods and the retailer then decides the order level and sells the goods in the market. Specifically, a quadratic cost function is assumed here to approximate the U-shape cost curve commonly observed in industries. Two kinds of contracts offered by the supplier are investigated, namely wholesale price contract and quantity dependent contract. Wholesale price is fixed under the first contract but varies depending on order level under the second one. We show that certain wholesale price contract successfully induces the retailer to order at a level such that supply chain profit is maximized, but extra cost in implementation may occur due to supplier's disagreement on this price. Given this, we propose an efficiency measure to show to what extent the wholesale price contract helps to increase supply chain profit. For quantity dependent contract, we show that it can coordinate the supply chain and leads to a proportional division of supply chain profit. We then generalize the analysis to cover the case of multiple retailers and single supplier where similar results are also obtained.published_or_final_versionThe 40th International Conference on Computers and Industrial Engineering, (CIE 2010), Hyogo, Japan, 25-28 July 2010. In Proceedings of the International Conference on Computers & Industrial Engineering, 2010, p. 1-

Investigations of urethral sphincter activity in mice with bladder hyperalgesia before and after drug administration of gabapentin.

PurposeThis study investigated the effect of gabapentin on lower urinary tract dysfunction focusing on urethral activities and cystitis-induced hyperalgesia in a mouse model of painful bladder syndrome/interstitial cystitis (PBS/IC). The electromyography (EMG) of external urethral sphincter (EUS) was difficult to obtain, but contained useful information to examine the drug effect in mice.MethodsFemale C57BL/6J mice were intraperitoneally (ip) administration with either saline or 200 mg/kg of cyclophosphamide (CYP) 48 h before experimental evaluation. Cystitis mice were treated with administration of gabapentin (25 or 50 mg/kg, ip). Cystometry and EUS EMG were obtained and analyzed during continuous bladder infusion. The visceral pain-related visceromotor reflex (VMR) was recorded in response to isotonic bladder distension.ResultsCystitis mice showed shorter inter-contraction intervals and increased occurrence of non-voiding contractions during bladder infusion, with increased VMR during isotonic bladder distension, indicating cystitis-induced bladder hyperalgesia. Gabapentin (50 mg/kg) suppressed effects of CYP on cystometry, but not on EUS EMG activity, during bladder infusion. The effect on urodynamic recordings lasted 4 h. VMR was significantly reduced by gabapentin.ConclusionsThe present study showed that CYP-induced cystitis in mice is a model of visceral hyperalgesia affecting detrusor contractions, not urethral activations. The technique of using EUS EMG to evaluate the drug effects on urethral activities is novel and useful for future investigations. Gabapentin can be as a potential treatment for detrusor overactivity and PBS/IC

A Search for Neutrino Oscillations.

A search for neutrino oscillation has been carried out at LAMPF (the Los Alamos Meson Physics Facility). The engineering run in the 1986 cycle has demonstrated that the detector works as designed. The probability of oscillation between two neurino types \nu\sb1 and \nu\sb2 can be parameterized by two variables: (1) the difference between the squares of the masses of two mass eigenstates $\delta$m\sp2 $(\equiv\ \vert$m\sb1\sp2 - m\sb2\sp2\vert), and (2) the mixing angle $(\theta)$ between the two states. In this experiment, we set limits on the oscillations \bar\nu\sb\mu $\to$ \bar\nu\sb{\rm e} and \nu\sb{\rm e} $\to$ \bar\nu\sb{\rm e} as a function of $\delta$m\sp2 and sin\sp2 2\Theta. For the \bar\nu\sb\mu \to \bar\nu\sb{\rm e} oscillation, we obtained sin\sp22\theta $\u3c$ 0.14 (90% C.L.) in the limit of large mass difference $\delta$m\sp2 between neutrino mass eigenstates m\sb1 and m\sb2; and an upper limit on the product $\delta$m\sp2sin\sp2 2\theta $\u3c$ 0.35 eV\sp2 in the limit of small mass difference. For the \nu\sb{\rm e}\to\bar\nu\sb{\rm e} oscillation, we obtained sin\sp2 2\theta $\u3c$ 0.21 (90% C.L.) in the limit of large mass difference $\delta$m\sp2 and an upper limit on the product $\delta$m\sp2sin\sp2 2\theta $\u3c$ 0.39 eV\sp2 in the limit of small mass difference

Chinese migration and settlement in Australia, with special reference to the Chinese in Melbourne

A review of literature showed that studies relevant to the Chinese in Australia were mostly concerned with immigration laws and early Chinese settlements, and that little had been done on post- World War II Chinese communities in Australia. The present study utilizes Australian censuses, immigration and marriage statistics, etc. to trace the main outline of Chinese migration and settlement. in Australia since 1861, and then examines the present pattern of settlement in Melbourne in the form of a survey in 1968. Australian censuses were particularly useful as a basic source material. This thesis can be readily divided into two parts: The first part deals with the history of Chinese migration and settlement in Australia and the second part deals with the Melbourne survey