Discrete Ordinates Methods for Transport Problems with Curved Spatial Grids.

The method of characteristics (MOC) has been favored for many recent whole core transport codes; some current research codes are: the nTRACER code from Seoul National University, the MPACT code from the University of Michigan, and the Dragon code from Ecole Polytechnique de Montreal. However, it is well-known that whole core transport with MOC is both computational expensive and requires significant storage. On the other hand, discrete ordinates (SN) methods have been successfully applied to large systems, as has been demonstrated by the computer code Attila. However, all previous discrete-ordinates methods implemented in available production computer codes were formulated only for problems containing spatial cells with planar boundaries. This creates geometric approximations and inefficiencies for modeling any physical system with curved boundaries â the curved boundaries must be approximated using a greatly many very fine spatial cells, each fine cell having a planar boundary. In this thesis, we derive, implement, and test 2-D discrete ordinates methods, which are applicable for systems having curved interfaces between material regions, and which treat these curved surfaces analytically. The key benefits of "these" discrete ordinates methods on curved spatial grids over the MOC method include: (i) the ability to use standard highly-optimized quadrature sets, (ii) a single user-specified spatial grid, (iii) a simple extension to 3-D transport, and (iv) a small memory footprint for the computer.PhDNuclear Engineering and Radiological SciencesUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/116757/1/chyliu_1.pd

Capacity Limitation and Optimization Strategy for Flexible Point-to-Multi-Point Optical Networks

Point-to-multi-point (PtMP) optical networks become the main solutions for network-edge applications such as passive optical networks and radio access networks. Entropy-loading digital subcarrier multiplexing (DSCM) is the core technology to achieve low latency and approach high capacity for flexible PtMP optical networks. However, the high peak-to-average power ratio of the entropy-loading DSCM signal limits the power budget and restricts the capacity, which can be reduced effectively by clipping operation. In this paper, we derive the theoretical capacity limitation of the flexible PtMP optical networks based on the entropy-loading DSCM signal. Meanwhile, an optimal clipping ratio for the clipping operation is acquired to approach the highest capacity limitation. Based on an accurate clipping-noise model under the optimal clipping ratio, we establish a three-dimensional look-up table for bit-error ratio, spectral efficiency, and link loss. Based on the three-dimensional look-up table, an optimization strategy is proposed to acquire optimal spectral efficiencies for achieving a higher capacity of the flexible PtMP optical networks.Comment: The paper has been submitted to the IEEE Transactions on Communication

Hybrid method for predicting ship manoeuvrability in regular waves

The ship's manoeuvring behaviour in waves is significantly different from that in calm water. In this context, the present work uses a hybrid method combining potential flow theory and Computational Fluid Dynamics (CFD) techniques for the prediction of ship manoeuvrability in regular waves. The mean wave-induced drift forces are calculated by adopting a time domain 3D higher-order Rankine panel method, which includes the effect of the lateral speed and forward speed. The hull-related hydrodynamic derivatives are determined based on a RANS solver using the double body flow model. The two-time scale method is applied to integrate the improved seakeeping model in a 3-DOF modular type Manoeuvring Modelling Group (MMG model) to investigate the ship's manoeuvrability in regular waves. Numerical simulations are carried out to predict the turning circle in regular waves for the 5175 container carrier. The turning circle's main characteristics as well as the wave-induced motions are evaluated. A good agreement is obtained by comparing the numerical results with experimental data obtained from existing literature. This demonstrates that combining potential flow theory with CFD techniques can be used efficiently for predicting the manoeuvring behaviour in waves. This is even more true when the manoeuvring derivatives cannot be obtained from model tests when there is lack of such experimental data

A novel method for purifying bluetongue virus with high purity by co-immunoprecipitation with agarose protein A

<p>Abstract</p> <p>Background</p> <p>Bluetongue virus (BTV) is an icosahedral non-enveloped virus within the genus <it>Orbivirus </it>of <it>Reoviridae </it>and exists as 24 distinct serotypes. BTV can infect all ruminant species and causes severe sickness in sheep. Recently, it was reported that BTV can infect some human cancer cells selectively. Because of the important oncolysis of this virus, we developed a novel purifying method for large-scale production. The purifying logic is simple, which is picking out all the components unwanted and the left is what we want. The process can be summarized in 4 steps: centrifugation, pulling down cell debrises and soluble proteins by co-immunoprecipitation with agarose Protein A, dialysis and filtration sterilization after concentration.</p> <p>Results</p> <p>The result of transmission electron microscope (TEM) observation showed that the sample of purified virus has a very clear background and the virions still kept intact. The result of 50% tissue culture infective dose (TCID₅₀) assay showed that the bioactivity of purified virus is relatively high.</p> <p>Conclusions</p> <p>This method can purify BTV-10 with high quality and high biological activity on large-scale production. It also can be used for purifying other BTV serotypes.</p

Targeting P-Glycoprotein: Nelfinavir Reverses Adriamycin Resistance in K562/ADR Cells

Background/Aims: The emergence of multidrug resistance (MDR) caused by P-glycoprotein (P-gp) overexpression is a serious obstacle to the treatment of chronic myelocytic leukemia. In recent years, some clinical trials have shown that nelfinavir (NFV), a traditional anti-HIV drug, has anti-cancer effects. Some researchers have also shown NFV might be a potential P-gp inhibitor. This study is aimed at investigating whether nelfinavir can act as an MDR-reversal drug and to clarify its molecular mechanism as well. Methods: K562 and K562/ADR cell lines were applied in the study. Cytotoxicity was detected by CCK-8 reagents. Cell apoptosis was detected by flow cytometry and inverted fluorescence microscopy to detect the binding of apoptotic dyes to cells. Western blot was used to detect the expression of proteins. Drug-protein molecular docking simulation by using Sybyl-x 2.0 software. Results: Non-toxic concentrations of NFV (1.25–5 μM) could reverse Adriamycin (ADR), colchicine, paclitaxel, and imatinib resistance of K562/ADR cells, with reversal indexes of up to 10.8, 7.4, 57, and 9.3, respectively. NFV inhibited P-gp efflux function, as evidenced by the significant increase in the intracellular accumulation of ADR and Rho-123, without affecting P-gp protein and mRNA expression levels. Further ATP content detection and molecular docking simulations showed that NFV could decrease intracellular ATP content and has a high affinity with the active functional regions of P-gp, respectively. When co-administered with ADR, NFV increased intracellular reactive oxygen species as well as blocked the ERK/Akt signaling pathway, leading to cell apoptosis. Conclusion: NFV inhibited P-gp function, decreased intracellular ATP content, and promoted cell apoptosis in K562/ADR cells, thereby reversing MDR. These findings encourage further animal and clinical MDR studies with a combination therapy consisting of NFV and chemotherapeutic drugs