We present an algorithm for performing view-dependent simplifications of a triangulated polygonal model in real-time. The simplifications are dependent on viewing direction, lighting, and visibility and are performed by taking advantage of image-space, objectspace, and frame-to-frame coherences. A continuous level-of-detail representation for an object is first constructed off-line. This representation is then used at run-time to guide the selection of appropriate triangles for display. The list of displayed triangles is updated incrementally from one frame to the next. Our approach is more effective than the current level-of-detail-based rendering approaches for most scientific visualization applications where there are a limited number of highly complex objects that stay relatively close to the viewer.

Infectious diseases provide a particularly clear illustration of the spatiotemporal underpinnings of consumer-resource dynamics. The paradigm is provided by extremely contagious, acute, immunizing childhood infections. Partially synchronized, unstable oscillations are punctuated by local extinctions. This, in turn, can result in spatial differentiation in the timing of epidemics and, depending on the nature of spatial contagion, may result in traveling waves. Measles epidemics are one of a few systems documented well enough to reveal all of these properties and how they are affected by spatiotemporal variations in population structure and demography. On the basis of a gravity coupling model and a time series susceptible-infected-recovered (TSIR) model for local dynamics, we propose a metapopulation model for regional measles dynamics. The model can capture all the major spatiotemporal properties in prevaccination epidemics of measles in England and Wales.

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II. Modelling of a Heat ExchangerTwo models for two different control schemes are developed for a parallel flow heat exchanger. First by spatially lumping a heat exchanger model, a good approximate model which has a high system order is produced. Model reduction techniques are applied to these obtain low order models that are suitable for dynamic analysis and control design. The simulation method is discussed to ensure a valid simulation result.

Abstract. No control cell line was available for previous RNA interference studies on reversal of multidrug resistance (MDR) in colon cancer cells. Here, human COLO 320DM, with HT-29 as the control, colon cancer cell lines were used to investigate the reversal of MDR1/P-gp-dependent MDR by siRNA (#4123 and #4029 MDR1 siRNAs) targeting to MDR1 mRNA. Both siRNAs inhibited expression of MDR1 and P-gp in COLO 320DM. The minimum inhibition concentrations were 5 nmol/l of #4123 and 25 nmol/l of #4029. #4123 MDR1 siRNA took effect in 4, 5 and 6 days at doses of 5, 25 and 100 nmol/l, respectively. Increased cytotoxicity of the antitumor drugs adriamycin and vincristine with increased intracellular adriamycin accumulation accompanied inhibition of MDR1 mRNA and P-gp expression. No such effects were found in the HT-29 control. MDR1 siRNAs specifically reversed the MDR of colon cancer cells demonstrating a possible new approach for treating MDR1/P-gpdependent multidrug resistance. IntroductionColon cancer is the second leading cause of cancer death in the United States (1). Most patients with colon cancer are in its advanced stage by the time of diagnosis (2), so surgery is rarely sufficient treatment. Consequently, chemotherapy is very important in the treatment of colon cancer. However, the effectiveness of chemotherapy is limited because colon cancer cells become drug resistance (3).Classical multiple drug resistance (MDR) in cancer cells is thought to be related to the overexpression of P-glycoprotein (P-gp, MDR1) (4). P-glycoprotein is a 170-kDa transmembrane protein and a member of the ATP-binding cassette transporter superfamily. P-glycoprotein functions as an energydependent efflux pump, thereby resulting in decreased concentrations of intracellular drugs and resistance to the chemotherapeutic effect of these drugs. To improve the effect of chemotherapy in the treatment of colon cancer, one of the major challenges is how to reverse MDR in colon cancer cells. In previous studies, calcium antagonists such as verapamil (5), antisense oligonucleotides (6) and hammerhead ribozymes (7) were found to modulate MDR1/P-gp-dependent MDR by down-regulating the expression of the MDR1 mRNA and P-gp. However, calcium antagonists may cause heart failure and hypotension (8), and the clinical benefit of antisense oligonucleotides and hammerhead ribozymes has not been realized. So successful reversal of drug resistance is still awaiting new therapeutic strategies or pharmaceuticals.A novel means for specific inhibition of a target gene is the use of small interfering RNA (siRNA). These 21-23 nucleotides (nt) long, double-stranded RNA (dsRNA) molecules can direct degradation of eukaryotic mRNAs in a sequence-specific manner (9). This ubiquitous mechanism of gene regulation in plants and animals was designated as RNA interference (RNAi) (10).In this study, we chose the COLO 320DM cell line for our colon cancer model to investigate the reversal of MDR using siRNA. COLO 320DM has been reported to express P-gp and has MDR to many chemothe...

Structurally ordered intermetallic structure is an efficient catalyst design strategy to significantly improve the catalytic performance of Pt alloy electrocatalysts for oxygen reduction reaction in fuel cells. However, a high structural ordering degree generally relies on high-temperature annealing, which results in detrimental catalyst particle sintering. Herein, we reveal that the incompatibility between high ordering degree and minimum particle sintering during thermal annealing can be resolved through rational development of structurally ordered Pt ternary alloys. Ordering transformation mediated by high-temperature annealing of three representative Pt ternary alloys (Pt–Fe–Co, Pt–Ni–Co and Pt–Fe–Ni) at a similar Pt composition was systematically studied. It was found that Fe can significantly promote the structural ordering due to a faster atomic diffusion, whereas Co can effectively inhibit the particle sintering. As a result of the synergy between Co and Fe, the ordered PtCoFe catalyst exhibited the highest ordering degree after thermal annealing at 600 °C with the minimum nanoparticle growth, leading to the highest catalytic activity (0.65 A/mgPt at 0.9 V, 4 times that of pure Pt catalyst) and best stability (16% drop after 10,000 potential cycles). This study provides important clues for the rational design of high-performance structurally ordered ternary Pt alloys.

When we reuse a code fragment in an open source system, it is very important to know the history of the code, such as the code origin and evolution. In this paper, we propose an integrated approach to code history tracking for open source repositories. This approach takes a query code fragment as its input, and returns the code fragments containing the code clones with the query code. It utilizes publicly available code search engines as external resources. Based on this model, we have designed and implemented a prototype system named Ichi Tracker. Using Ichi Tracker, we have conducted three case studies. These case studies show the ancestors and descendents of the code, and we can recognize their evolution history.