Management of rainfall-related environmental risks in urban area

Rainfall brings urban residents both benefits, such as water resources, but also adverse risks such as flooding. Additionally, it has been recognized that wet weather run-off discharges pollutants

and transfers chemicals and pathogen bacteria into the aquatic ecosystem. This causes not only deterioration of water quality but also environmental pollution risk. Both the flood risk and environmental pollution risk are treated here as ‘rainfall-related environmental risks’. Although these two kinds of risks are quite different in their characteristics, the main purpose of urban wet weather flow management is how to decrease these risks. Furthermore, these risks have a similar background which is concerned with both the urban structure and the life-style of urban residents. Recently, flood disaster has occurred in the Japanese urban area with increasing frequency causing damage due not only to rainfall intensity, but also the vulnerability of urban structures against heavy storms. Although there has been urban area expansion and a decline in substrate permeability, wet weather flow management in Japan is aimed simply to drain the increased run-off volume quickly. As for the management of hazardous chemicals which might be discharged together with rainfall run-off, this has not been implemented sufficiently. It is necessary to develop a methodology to reduce rainfall-related environmental risks in urban wet weather flow management. In this paper, the possible risk management process and control options of rainfall-related risks will be discussed after a summary of both the similar and differing points between inundation risk and environmental pollution risk. As a result, it is deemed necessary to operate a scheme to raise the rainfall-related environmental risk perception level of urban residents to ensure their participation in risk management.     

The relation between the speed of demand saturation and the dynamism of the labour market

The purpose of this paper is to examine the medium run effect of the speed of demand saturation on the dynamism of the labour market which involves factors such as the growth of employment and real wage rate, using a computer simulation of the stochastically multi-sectoral pure labour model with a logistic demand function. From the simulation, we obtain the evolutions of the expectation of the employment rate and the real wage rate, supposing three cases where the speed of demand saturation for a product that stochastically emerges is, ceteris paribus, different. As a result, it is demonstrated that the faster growth of demand for a product that emerges stochastically accelerates the growth of employment, but decelerates the growth of real wage rate. The result depends on the heterogeneity of the agents, which is neglected by mainstream economics.     

Internationalization in Japan’s service industries

The relatively low level of internationalization in Japan’s service industries is a cause of real concern among policy-makers and service industry executives. Explanations have focused on distinctive features of Japan’s culture, particularly its service culture, and idiosyncratically demanding customers. Two additional factors are also of significance: the complexity of the customer interface and process embeddedness in the home country. Mapping service sectors in terms of these two dimensions offers insights into the challenges faced by Japanese service firms, while also providing a framework for assessing home country effects in general.     

Inter-regional Population Migration in Russia: Using an Origin-to-Destination Matrix

This study examines regional economic conditions and their effects on inter-regional population redistribution patterns in Russia. After reviewing striking changes in population flows before and after the collapse of the former Soviet Union, an application of the gravity model to population migration in Russia in 2003 is presented using a newly obtained inter-regional in- and out-migration flow matrix supplied by Rosstat (formerly Goskomstat). Gross migration patterns since the year 2000, when large transformational population flows ceased, have not been investigated so far in the existing literature. The analysis conducted focuses on geographical factors, which have been basically omitted in existing literature on migration patterns in post-Soviet Russia, and the attractiveness of Moscow and surrounding regions and resource-mining areas is clearly presented.     

Behaviour of arsenic species in batch activated sludge process: biotransformation and removal.

The behaviour of As(III), As(V), MMA(v) and DMA(v) in batch activated sludge process were investigated. Experiments were carried out by using aerobic and anoxic reactors with an initial As concentration of 100 microjg I(-1). Under aerobic condition, As(III) was oxidized to As(V) within 9 hours, some part of MMA(v) was methylated to DMA(v) and some other part was demethylated to As(III), which in turn was immediately oxidized to As(V). Under anoxic condition, As(V) was reduced to As(III) within the same time-course. No significant transformation occurred during experiments conducted with DMA(v). It was found that all reactions were biologically mediated. The overall As removal was low (< 20%) during the experiments. Although a relationship seems to exist between the sludge concentration and As removal, it is concluded, under the conditions of our study, that the activated sludge process cannot remove arsenicals efficiently. However, it can control their transformations well. Thus, if associated with an appropriate technology, the activated sludge can be used for As pre-oxidation to treat As contaminated wastewaters. Finally, care must be taken on possible presence of MMA(v) in the influent of any wastewater treatment plant as it can be easily oxidized by the activated sludge.     

Vertical mass and momentum transport in open-channel flows with submerged vegetations

The importance of flow and turbulence to the ecology of aquatic benthic organism has been widely reported. Aquatic vegetation is one of environmental variables that influence turbulence and the ecological condition of rivers. Aquatic canopies have the potential to greatly improve water quality through the removal of nutrients and trace metals. To describe the efficiency of this removal, we must be able to quantify the rate of vertical mixing. In fully submerged vegetation flows, coherent turbulent motions are generated near the vegetation edge and these large-scale eddies control the vertical exchange of mass and momentum. It is therefore important for river management to investigate hydrodynamic characteristics and coherent eddies in open-channel flows with vegetation canopies. Turbulence structure and transport mechanism of momentum in vegetated flows have been investigated intensively in the past decade.However, the effect of the submerged vegetation on the vertical mass transport and turbulent diffusion has not been fully investigated. Therefore, in the present study, continuous dye injection experiments were conducted to evaluate the mass transport structure in open-channel flow with rigid vegetation models by changing the vegetation density. A combination technique between PIV and planar laser-induced fluorescence (LIF) was developed by using two sets of CCD cameras, to measure the instantaneous velocity and concentration field simultaneously. The technique is capable of determining the turbulent scalar flux as well as the Reynolds stress, mean and fluctuating velocity and concentration fields. Consequently, the effects of coherent vortices on the vertical turbulent diffusivity were examined in detail.     

An Empirical Model of Land Use Change in China

The aim of this paper is to develop an empirical model of land use change that integrates the growth of regional economy and land use change in a developing country such as China. The concept of ecological growth in terms of regional resources and population is introduced to make an empirical model of land use changes. It is shown that the model might be an efficient tool to analyze and predict regional land use change, and that the policies based on it can play an important role in land use change in China.     

Interregional Fertility Differentials and Agglomeration

In this study, we construct an interregional trade model that includes endogenous fertility rates. The presented model shows that the agglomeration of manufacturing firms in a large region causes fertility rates to become lower than in a small region. We also find that a decrease in transportation costs results in the agglomeration of manufacturing firms, which lowers fertility rates in both large and small regions. In addition, comparing the competitive equilibrium with the optimal equilibrium, the fertility rates may be inefficiently small.     

Small sample properties of the mixed regression estimator

In this paper, the small sample properties of the mixed regression estimator are examined when prior information may be biased and when the ration of the variance of the prior restriction errors to the variance of the sample errors is unknown. The mean square error of the mixed regression estimator is derived, and it is shown that the mixed regression estimator gets dominated by the ordinary least squares estimator in terms of the mean square error as the bias of prior information gets larger.     

Urbanizing economics

Action takes place at a given time and place. As a science of human action, economics is, therefore, just as much about the spaces where real action occurs as it is about real time. The implications of real time for social order is better recognized than the significance of “action space.” The living city is the principal locus of action space and enabler of social change as well as the source of fundamental concepts in economic theory. Just as a loss of density and diversity in cities tends to retard dynamic discovery and development, the turn in economic theory in the mid-20th century toward static equilibrium reflected a move from an urban-based to a plantation-based conception of the economy—from the city to the farm. Some recent developments in network theory, game theory, and geography, however, can be interpreted as a re-urbanization of economics.