Modelling price fluctuations of ferrous scrap

This paper presents a model that analyses the interrelationships between markets of light non-flat steel products (such as concrete reinforcing bars) and iron and steel scrap, both of which are characterized by wide price fluctuations. The model, which was developed as a linear complementarity programming problem, seems to be robust in analysing unstable and simulataneous price movements of those markets. The model may be applied to other metal and scrap markets without substantial changes.     

Unusually high levels of thyroid hormones in isolated and/or monolayer-cultured pig thyroid epithelial cells

The Science of Nature -     

What Anthropogenic Radionuclides (90Sr and 137Cs in Atmospheric Deposition, Surface Soils and Aeolian Dusts Suggest for Dust Transport over Japan

Currently, atmospheric anthropogenic radionuclides (particulate) are controlled by suspension of the surface dust containing those radionuclides (resuspension). We have found, therefore, that such radionuclides can be used as tracers of the surface dust suspension, transport and its subsequent deposition in distant areas. The ¹³⁷Cs/⁹⁰Sr activity ratios in the atmospheric deposition, without the direct influence of nuclear tests and accidents, at the Meteorological Research Institute (MRI, Tsukuba, Japan) during the 1990s were fairly low (average: 2.1). This value is not in agreement with the ratios in Japanese surface soils (range of averages: 4–7), which had been considered as the primary source of the deposited dust. This suggests that the current atmospheric dust deposition in Japan is a mixture of local and remote components. The remote component could be an aeolian dust that has been transported long distances from arid areas. The major component is most likely to be Asian dust. It was further hypothesized that other remote source may exist beyond the Asian domain, based on accumulated observations and model results. To obtain more information about the dust transport, Sahara dust deposited in Monaco in 2002 and a suspended dust collected in the Taklamakan area in 2001 were analyzed for ⁹⁰Sr and ¹³⁷Cs. The Taklamakan dust exhibited a ¹³⁷Cs/⁹⁰Sr ratio of about 4, which is within the range of atmospheric deposition observed at the MRI, while the Sahara dust exhibited a higher ¹³⁷Cs/⁹⁰Sr ratio (about 13). Although the present Sahara datum was negative for our hypothesis of ‘hyper-range transport’, the seasonal change of the ¹³⁷Cs/⁹⁰Sr ratio in the atmospheric deposition observed at the MRI requires an aeolian dust source having a low ¹³⁷Cs/⁹⁰Sr ratio, other than Asian dust.     

Development and verification of new evaluation indicators for chemical management in corporations to meet WSSD goals

During the World Summit on Sustainable Development (WSSD), it was agreed that adequate chemical management based on risk assessment should be achieved by 2020. To achieve the WSSD goals, it is important to evaluate and enhance the voluntary activities of corporations because they are the main agents dealing with chemical management. To this end, we developed new evaluation indicators that were combined with the SCP Axes (Science Axis - evaluation of the scientific basis; Capacity Axis - evaluation of the abilities of personnel and organizations; and the Performance Axis - evaluation of results of activities and information disclosure to the community, etc.) and 4 elements (hazard assessment, exposure assessment, risk assessment, and risk management). We administered surveys to Japanese corporations from 2006 to 2008 to verify the developed indicators. The survey results showed that the activities concerning chemical management were very different across corporations for each industry category and that the hazard assessment improved, reflecting a vigorous social movement that included legal obligations. Therefore, the new evaluation indicators possessed high resolution and precisely grasped the changes in corporate activities. We found that these indicators provided an effective way to understand corporate activities designed to meet the goals of the WSSD.     

Hydrodynamic characteristics and related mass-transfer properties in open-channel flows with rectangular embayment zone

Consecutive groynes and embayments form dead water zones, where sedimentation and high concentrations of pollutants are often observed. It is thus very important to understand the mass and momentum exchange between the main channel and side cavities in rivers and hydraulic engineering structures. The spanwise gradient of the streamwise velocity near the junction produces small-scale turbulent vortices because of shear instability. Furthermore, large-scale horizontal circulation is also generated in the cavity zone. These coherent turbulent structures play a significant role in mass and sediment transfer at the boundary between the mainstream and embayment. However, the relation between turbulence and mass transfer is poorly understood. In this study, we performed particle image velocity and laser-induced fluorescence experiments using a laboratory flume, laser light sheets and a high-speed CMOS camera. We examined the exchange properties of a dye as a function of bed configuration and sedimentation effect. Both primary and secondary gyres were observed in the flat bed and downward-sloping bed, whereas the primary gyre was prevalent in the upward-sloping bed. Moreover, the horizontal circulation strongly affected the mass-transfer properties between the mainstream and side cavity.     

Food webs are built up with nested subwebs

Nested structure, in which specialists interact with subsets of species with which generalists interact, has been repeatedly found in networks of mutualistic interactions and thus is considered a general feature of mutualistic communities. However, it is uncertain how exclusive nested structure is for mutualistic communities since few studies have evaluated nestedness in other types of networks. Here, we show that 31 published food webs consist of bipartite subwebs that are as highly nested as mutualistic networks, contradicting the hypothesis that antagonistic interactions disfavor nested structure. Our findings suggest that nested networks may be a common pattern of communities that include resource-consumer interactions. In contrast to the hypothesis that nested structure enhances biodiversity in mutualistic communities, we also suggest that nested food webs increase niche overlap among consumers and thus prevent their coexistence. We discuss potential mechanisms for the emergence of nested structure in food webs and other types of ecological networks.     

Statistical Interpretation of the Impact of Forest Growth on Streamflow of the Sameura Basin, Japan

A forested mountainous basin, the Sameura basin, located in Shikoku Island of Japan, experienced increased forest growth in the period from 1953 to 1994, like which occurred across the country. The impact of the forest growth on streamflow of the basin was assessed using statistical trend analysis. Annual maximum daily flow, annual minimum 5-day flow, and annual total runoff decreased by 55.8, 75.8, and 39.6%, respectively, over the period. However, the annual maximum 6-day, annual minimum 41-day, and annual total precipitation, respectively associated with annual maximum daily flow, annual minimum 5-day streamflow, and annual total runoff did not decrease. Annual and monthly temperature, which evapotranspiration positively related to, did not increase except in January. This demonstrates that the forest growth is responsible for the decrease in all these three flow regimes. The increase in evapotranspiration due to the forest growth resulted in the decrease in both total runoff and low flow. Thus, it seems that forest can hardly function to both reduce flood peaks during flood periods and increase water supply during drought periods.     

Recent trends of plutonium fallout observed in Japan: plutonium as a proxy for desertification

Plutonium in monthly deposition samples collected in Tsukuba (the Meteorological Research Institute), Japan from 1990 to end of 2001 is reported, together with monthly plutonium deposition in Nagasaki and Yonaguni in 2000. The annual deposition of (239,240)Pu during the period from 1990 to 2001 shows no systematic interannual variation. However, monthly (239,240)Pu depositions show a typical seasonal variation with a maximum in spring season (March to April), which corresponds to seasonal cycle of soil dusts originating from the East Asian arid area. Plutonium isotopic ratios in the deposition samples suggest that significant amounts of the recent (239,240)Pu deposition observed in Japan are attributed to the resuspension of plutonium-bearing surface soil particles; resuspended plutonium originates from the East Asian arid areas. The recent increased tendency of (239,240)Pu content in residues in deposition samples may reflect desertification in the East Asian continent.     

Numerical analysis of gas explosion inside two rooms connected by ducts

Simulations of gas explosion of hydrogen/air mixture inside two rooms connected by ducts are carried out. Scalar transport chemical reaction model and LES turbulence model are utilized to reduce the calculation load and to conduct real-scale analysis. The effects of ignition source locations and volume of ignited room are analyzed, and the time history of pressure and rate of pressure rise in each room are focused in this study. When the volume of the ignited room is larger than the other room, the high pressure from the other room causes a force to act on the partition to the ignited room. This study indicates that the current technique can predict specific features of gas explosions inside two rooms connected by the ducts.