A Precomputed Approach for Real-Time Haptic Interaction with Fluids

The key to enhancing perception of the virtual world is improving mechanisms for interacting with that world. Through providing a sense of touch, haptic rendering is one such mechanism. Many methods efficiently display force between rigid objects, but to achieve a truly realistic virtual environment, haptic interaction with fluids is also essential. In the field of computational fluid dynamics, researchers have developed methods to numerically estimate the resistance due to fluids by solving complex partial differential equations, called the Navier-Stokes equations. However, their estimation techniques, although numerically accurate, are prohibitively time-consuming. This becomes a serious problem for haptic rendering, which requires a high frame rate. To address this issue, we developed a method for rapidly estimating and displaying forces acting on a rigid virtual object due to water. In this article, we provide an overview of our method together with its implementation and two applications: a lure-fishing simulator and a virtual canoe simulator     

Purification and characterization of an epsilon-poly-L-lysine-degrading enzyme from the epsilon-poly-L-lysine-tolerant Chryseobacterium sp. OJ7

The epsilon-poly-L-lysine-degrading enzyme of the epsilon-poly-L-lysine-tolerant Chryseobacterium sp. OJ7 was purified and characterized. The bacterium excreted the enzyme into the culture filtrate. The purified enzyme has a molecular mass of approximately 38.4 kDa and consists of two identical subunits with a molecular mass of 19.5 kDa. The enzyme catalyzed the endo-type degradation of epsilon-poly-L-lysine. A correlation between the epsilon-poly-L-lysine tolerance of the bacterium and the high epsilon-poly-L-lysine-degrading activity was suggested.     

Sidelobe suppression of s.a.w. resonant filter using twin-turn reflectors

Sidelobe suppression of twin-turn reflector filters is accomplished using longitudinal deformations of i.d.t.s. 41° Y-X LiNbO3 substrate is used, and in experiment the Japanese t.v.i.f. specification is nearly satisfied.     

Left ventricular mass regression after implantation of St. Jude Medical cardiac valves in small aortic roots

In this study, we analyzed the extent of regression of left ventricular hypertrophy in patients who received small St. Jude Medical (SJM) aortic valves and compared the results with those of another group receiving larger valves. Eighty-eight patients received either 19 or 21 mm valves (Group 1, 25 patients) or either 23 or 25 mm valves (Group 2, 53 patients). Echocardiographic studies were done before the operation and 5 years postoperatively. At follow-up a significant reduction in the left ventricular mass was found for both patient groups (p < 0.0001). Doppler echocardiography derived pressure gradients for both groups were obtained during the follow-up period. As expected, the patients in Group 1 had higher peak pressure gradients than did those in Group 2. However, there was no significant difference between the 2 groups or any significant correlations between peak pressure gradients and body surface area (BSA). Actuarial survival was 84.7% at 15 years for Group 1 and 85.9% at 17 years for Group 2. Actuarial freedom from valve related events was 91.4% at 15 years for Group 1 and 82.7% at 17 years for Group 2. There was no significant difference in survival or valve related event free curves between the 2 groups. After implantations of SJM valves in small aortic roots, significant left ventricular mass regression was obtained, and the results were comparable to those for valves of other sizes. The long-term performance of aortic valve replacement with small valves was satisfactory as judged by improvement in the functional class of patients and survival statistics, the durability of the prosthesis, and valve related morbidity comparable to that of valves of other sizes.     

Frequency and clinical correlates of occlusive lesions of cerebral arteries in Japanese patients without stroke. Evaluation by MR angiography

BACKGROUND: In order to provide a morphological basis for the understanding of the role of nitric oxide (NO) in autonomic preganglionic neurons, the present study was designed to clarify the localization and distribution of nicotinamide adenine dinucleotide phosphate diaphorase (NADPH-d) activity, a marker of NO synthase, in the rabbit spinal cord. METHODS: 11 Chinchilla rabbits of both sexes were used in this study. Animals were kept under conditions of controlled light and heat regimens. NADPH-d activity was examined by histochemical methods. RESULTS: The presence of NADPH-d activity in the spinal cord was detected in the dorsal horn, around the central canal (lamina X) and in autonomic preganglionic neurons. Focused on the latter, there was a prominent NADPH-d activity between T1 and L5 segments in the intermediate zone and less intensive NADPH-d staining between S1 and S3 segments. Differences between the two parts of the autonomic system were seen in the arrangement (periodical in sympathetic, and continuous in parasympathetic), in the length of neuronal processes length (shorter in sacral preganglionic neurons) and in their localization (both are seen in the intermediolateral nucleus, but neurons of the sympathetic autonomic system can be found also medially towards the central canal, whilst those of the parasympathetic system were not). CONCLUSIONS: The present results suggest that NO can be used as a transmitter in preganglionic neurons and can be involved in autonomic and sensory processes. (Fig. 10, Ref. 37.)     

Experimental and numerical study on the relationship between creep crack growth properties and fracture mechanisms

Evaluation of creep crack growth properties taking microscopic aspects into account is effective for developing more accurate life prediction of structural components. The present study investigated the relationship between creep crack growth properties and microscopic fracture aspects for austenitic alloy 800H and 316 stainless steel. The growth rate of wedge-type intergranular and transgranular creep crack could be characterized by creep ductility. Creep damages formed ahead of the void-type crack tip accelerated the crack growth rate. Based on these experimental results, a three-dimensional finite element method (FEM) code, which simulates creep crack growth, has been developed. The effect of creep ductility on da/dt vs C* relations could be simulated based on the critical strain criteria. The diffusion of vacancies toward crack tip would accelerate the crack growth under creep conditions. The change of vacancy concentration during creep was computed for a three-dimensional compact-type (CT) specimen model by solving the diffusive equation under multiaxial stress field. The experimental results that crack growth was accelerated by creep damages formed ahead of the crack tip could be successfully simulated.     

On the Controlling Factor of Catalyst Temperature in C3H8—Air Mixture

Catalytic combustion of propane-air mixture was investigated.Platinum catalysts over a flat stainless steel with γ-alumina washcoat were employed.The employed burner has three catalysts set parallel to the mixture flow,spaced at an interval of 5,10 and 15 mm.Both experiment and numerical simulation were made at inlet temperature of 553 K,inlet velocity of 3 to 7 m/s and equivalence ratio of 0.3 to 0.5.In the numerical simulation,two-dimensional,steady state model was developed to calculate the temperature and species concentration in gas-phase.In this model.chemical reaction on the catalyst surface and that in the gas phase were assumed to occur in three-steps.The numerical results show good agreement with experimental results.It was found that the properties of the catalyst strongly affect the catalyst surface temperature.Especially,the thermal conductivity of catalyst has a great effect,while the emissivity of catalyst has less effect.     

Locational disadvantage of the hub

We show how spatial evolution is different between the two representative models of economic geography: [Krugman 99:483–499, 1991] and [Ottaviano et al. 43:409–436, 2002]. We analyze the impacts of falling transport costs on the spatial distribution of economic activities and welfare for a network economy consisting of three regions located on a line. It is normally considered that a hub city, i.e., a central region, always has locational advantage and manufacturing workers gain from trade. This is true in the former model, but not in the latter when markets are opened up to trade. This is because the price competition is so keen in the central region that the manufacturing sector moves to the peripheral regions, which aggravates the social welfare. We then show that when goods are close substitutes and share of manufacturing is of an intermediate level, the manufacturing activities completely disappear from the central region leading to a full agglomeration in one peripheral region.

Genes and Gene Networks Involved in Sodium Fluoride-Elicited Cell Death Accompanying Endoplasmic Reticulum Stress in Oral Epithelial Cells

Here, to understand the molecular mechanisms underlying cell death induced by sodium fluoride (NaF), we analyzed gene expression patterns in rat oral epithelial ROE2 cells exposed to NaF using global-scale microarrays and bioinformatics tools. A relatively high concentration of NaF (2 mM) induced cell death concomitant with decreases in mitochondrial membrane potential, chromatin condensation and caspase-3 activation. Using 980 probe sets, we identified 432 up-regulated and 548 down-regulated genes, that were differentially expressed by >2.5-fold in the cells treated with 2 mM of NaF and categorized them into 4 groups by K-means clustering. Ingenuity^® pathway analysis revealed several gene networks from gene clusters. The gene networks Up-I and Up-II included many up-regulated genes that were mainly associated with the biological function of induction or prevention of cell death, respectively, such as Atf3, Ddit3 and Fos (for Up-I) and Atf4 and Hspa5 (for Up-II). Interestingly, knockdown of Ddit3 and Hspa5 significantly increased and decreased the number of viable cells, respectively. Moreover, several endoplasmic reticulum (ER) stress-related genes including, Ddit3, Atf4 and Hapa5, were observed in these gene networks. These findings will provide further insight into the molecular mechanisms of NaF-induced cell death accompanying ER stress in oral epithelial cells.     

Effects of operating and design parameters on PEFC cold start

During startup from subzero temperatures the water produced in a polymer electrolyte fuel cell (PEFC) forms ice/frost in the cathode catalyst layer (CL), blocking the oxygen transport and causing cell shutdown once all CL pores are plugged with ice. This paper describes an experimental study on the effects of operating and design parameters on PEFC cold-start capability. The amount of total product water in mg cm⁻² during startup is used as an index to quantify the cold-start capability. The newly developed isothermal cold-start protocol is used to explore the basic physics of cold start, and the effects of purge methods prior to cold start, startup temperature and current density, and the membrane thickness are shown. The experimental data also confirm the current density effect predicted earlier by a multiphase model of PEFC cold start.