Toward Optimal Space Partitioning for Unbiased,Adaptive Free Path Sampling of Inhomogeneous Participating Media

Photo‐realistic rendering of inhomogeneous participating media with light scattering in consideration is important in computer graphics, and is typically computed using Monte Carlo based methods. The key technique in such methods is the free path sampling, which is used for determining the distance (free path) between successive scattering events. Recently, it has been shown that efficient and unbiased free path sampling methods can be constructed based on Woodcock tracking. The key concept for improving the efficiency is to utilize space partitioning (e.g., kd‐tree or uniform grid), and a better space partitioning scheme is important for better sampling efficiency. Thus, an estimation framework for investigating the gain in sampling efficiency is important for determining how to partition the space. However, currently, there is no estimation framework that works in 3D space. In this paper, we propose a new estimation framework to overcome this problem. Using our framework, we can analytically estimate the sampling efficiency for any typical partitioned space. Conversely, we can also use this estimation framework for determining the optimal space partitioning. As an application, we show that new space partitioning schemes can be constructed using our estimation framework. Moreover, we show that the differences in the performances using different schemes can be predicted fairly well using our estimation framework.     

A control law for vehicle merging inspired by dragonfly behavior

Autonomous control of vehicles has recently attracted considerable attention. In this sense, vehicle merging has become an important topic in this field of research. However, in conventional studies, the controlled vehicle must calculate the movement of other surrounding vehicles to complete the merge, requiring high computational costs. In this paper, we focus on dragonfly behavior to solve this issue. Indeed, insects can behave adaptively in the complex real world in spite of the limited size of their brains. They reduce the computational requirements of their brain by relying on different properties of their surroundings, basing their intelligent behaviors on simple strategies. The behavior of a dragonfly when chasing a prey is an example of these strategies. In this study, we address the vehicle merging maneuver by applying dragonfly’s strategies to control the movement of the merging vehicle. We propose a simple control method inspired by the aforementioned strategies and, finally, we present simulation results that were conducted to demonstrate the effectiveness of this method.     

The role of dispersed particles in strengthening and fracture mechanisms in a Mo-ZrC alloy processed by mechanical alloying

The tensile properties of a ZrC particle-dispersed Mo, which was processed by spark plasma sintering with mechanically alloyed powder, were investigated at room temperature and at elevated temperatures of 1170 to 1970 K. The Mo-ZrC alloy showed much higher strength at room temperature than a fully recrystallized pure Mo. The high strength of Mo-ZrC is mainly attributed to a very small grain size (about 3 μm). The main role of the ZrC particle is not to increase strength due to the particle-dislocation interaction, but to limit grain growth during sintering and to attain the very small grain size. The elongation at room temperature of Mo-ZrC was much lower than that of pure Mo. This is probably related to the higher interstitial contents. However, Mo-ZrC showed a large elongation of 180 pct at 1970 K and 6.7×10⁻⁴ s⁻¹. It was suggested that the ZrC particles stabilized the fine-grained microstructure yet provided no cavitation sites at 1970 K; as a result, the large elongation was attained.     

The impact of divorce precedents on the Japanese divorce rate

This paper undertakes a time series analysis of the Japanese divorce rate using annual data over the period 1964–2006. One of the key innovations of the paper is to use court decisions on divorce disputes to construct an index that seeks to measure how the probability of success in a divorce suit has changed over time. The computed index suggests that if it is the culpable party lodging the divorce suit, the probability of the suit being successful has clearly increased over time. The probability of winning a divorce suit appears to be an important factor in explaining the long-run rise in the Japanese divorce rate. The divorce rate also appears to be counter-cyclical.     

The soluble N-ethylmaleimide-sensitive factor attached protein receptor complex in growth cones: molecular aspects of the axon terminal development

Soluble N-ethylmaleimide-sensitive factor attached protein (SNAP) receptor (SNARE) mechanisms are thought to be involved in two important processes in axonal growth cones: (1) membrane expansion for axonal growth and (2) vesicular membrane fusion for mature synaptic transmission. We investigated the localization and interactions among the proteins involved in SNARE complex formation in isolated growth cone particles (GCP) from forebrain. We demonstrated that the SNARE complex is present in GCPs morphologically without synaptic vesicles (SVs) and associated with growth cone vesicles. However, the apparently SV-free GCP was lacking in the regulatory mechanisms inhibiting SNARE complex formation proposed in SV fusion, i.e., the association of synaptotagmin with the SNARE complex, and vesicle-associated membrane protein (VAMP)-synaptophysin complex formation. The core components of the SNARE complex (syntaxin, SNAP-25, and VAMP) accumulated for several days before postnatal day 7, when SVs first appeared, and preceded the accumulation of marker proteins such as synaptophysin, SV2, and V-ATPase. Our present results suggest that the SNARE mechanism for vesicular transmitter release is not fully functional in growth cones before the appearance of SVs, but the SNARE mechanism is working for membrane expansion in growth cones, which supports our recent report. We concluded that the regulation of the SNARE complex in growth cones is different from that in mature presynaptic terminals and that this switching may be one of the key steps in development from the growth cone to the presynaptic terminal.     

Seismic proof test of a reinforced concrete containment vessel (RCCV): Part 1: Test model and pressure test

In Japan, the Nuclear Power Engineering Corporation (NUPEC), sponsored by the Ministry of Economy, Trade and Industry (METI), has been conducting a series of seismic reliability proving tests using full-scale or close to full-scale models to simulate actual important equipment that is critical for seismic safety of nuclear power plants. The tests are intended to validate the seismic design and reliability with a sufficient margin even under destructive earthquakes. A series of tests was carried out on a reinforced concrete containment vessel (RCCV) for advanced boiling water reactor (ABWR) from 1992 to 1999. A large-scale high-performance shaking table at Tadotsu Engineering Laboratory, the largest in the world, was used for this test. Part 1 reports the test model and the results of pressure and leak tests. Part 2 describes test procedures, input waves and the results of verification tests such as changes of stiffness, characteristic frequency and damping ratio, the failure of the model and the load deflection. Part 3 shows the seismic safety margin that was evaluated from the energy input during the failure test to a design basis earthquake. Part 4 reports simulation analysis results by a stick model with lumped masses.     

Preparation of yttrium-90-labeled human macroaggregated albumin for regional radiotherapy

Helicobacter pylori and non-steroidal anti-inflammatory drugs are two of the most common causes of peptic ulceration. The aim of this review is to assess the possible inter-relationships between Helicobacter pylori and non-steroidal anti-inflammatory drugs in the pathogenesis of gastric and duodenal erosions and ulcers, with the aim of assessing if the presence of Helicobacter pylori is likely to increase the likelihood of non-steroidal anti-inflammatory drug-related gastroduodenal symptoms and lesions, and if eradication of Helicobacter pylori may reduce or prevent non-steroidal anti-inflammatory drug lesions. There appears to be more likelihood of dyspeptic symptoms in patients on long-term non-steroidal anti-inflammatory drugs when Helicobacter pylori is present. The balance of evidence also suggests that peptic ulcers and erosions in patients on long-term non-steroidal anti-inflammatory drugs may be more likely to occur in patients who are Helicobacter pylori positive compared to those who are Helicobacter pylori negative. Although Helicobacter pylori and non-steroidal anti-inflammatory drugs both increase the risk of peptic ulcer bleeding, the risk does not appear to be additive. There is increasing evidence from prospective studies that eradication of Helicobacter pylori may reduce the incidence of ulcers in patients on non-steroidal anti-inflammatory drugs. More prospective long-term studies are required. If Helicobacter pylori is confirmed to be a factor in this respect, it will aid in the targeting of patients at greatest risk of developing ulcers in patients on long-term non-steroidal anti-inflammatory drugs. Those at greatest risk are elderly patients, especially females, smokers, patients with a previous ulcer history, severe or debilitating arthritis or who have other chronic diseases. The addition of Helicobacter pylori to this list and its subsequent eradication may improve the outlook for these patients and help in the effective targeting of patients at greatest risk who are on long-term non-steroidal anti-inflammatory drugs.