Search

This paper studies the cusp catastrophe in a two-strategy population game with exogenous locational asymmetries and its application to spatial economics. We derive approximating games of two kinds: a cusp catastrophe form and a more general form. As a novel contribution of this paper, the effects of an arbitrary number of regional asymmetries are expressed using only three asymmetry parameters, thereby allowing for an analytical analysis. We find a new behavior with hysteresis using the general form. The usefulness of the forms is demonstrated for two economic geography models. A numerical recipe is presented to construct the cusp catastrophe form.

The fifth wave of the coronavirus disease 2019 (COVID-19) pandemic caused by delta variant infection depleted medical resources, and the Japanese government announced glucocorticoid use for outpatients. An appropriate outpatient-glucocorticoid treatment for COVID-19 has not been established; therefore, we created treatment manuals with indications for glucocorticoid administration in a care facility adequately equipped to manage patients with mild to moderate COVID-19. Thirty-eight patients (24 males, 14 females; mean age 40.5 ± 11.8 years) were treated with glucocorticoids from August 1 to October 1, 2021 [COVID-19 staging, mild (n = 1), moderate I (n = 19), and moderate II (n = 18)]. Patients were treated with 6.6 mg/day d.i.v. or 6 mg/day p.o. dexamethasone, or 20-30 mg/day p.o. prednisolone. The median (25

This paper studies the social acceptability and feasibility of a focused protection strategy against coronavirus disease 2019 (COVID-19). We propose a control scheme to develop herd immunity while satisfying the following two basic requirements for a viable policy option. The first requirement is social acceptability: the overall deaths should be minimized for social acceptance. The second is feasibility: the healthcare system should not be overwhelmed to avoid various adverse effects. To exploit the fact that the disease severity increases considerably with age and comorbidities, we assume that some focused protection measures for those high-risk individuals are implemented and the disease does not spread within the high-risk population. Because the protected population has higher severity ratios than the unprotected population by definition, the protective measure can substantially reduce mortality in the whole population and also avoid the collapse of the healthcare system. Based on a simple susceptible-infected-recovered model, social acceptability and feasibility of the proposed strategy are summarized into two easily computable conditions. The proposed framework can be applied to various populations for studying the viability of herd immunity strategies against COVID-19. For Japan, herd immunity may be developed by the proposed scheme if $${\mathcal {R}}_0 \le 2.0$$ R 0 ≤ 2.0 and the severity rates of the disease are 1/10 times smaller than the previously reported value, although as high mortality as seasonal influenza is expected.

This paper studies the social acceptability and feasibility of “herd immunity” strategies against coronavirus disease 2019 (COVID-19). To this end, we propose a control scheme that aims to develop herd immunity while satisfying the following two basic requirements for a viable policy option. The first requirement is social acceptability: the overall deaths should be minimized for social acceptance. The second is feasibility: the healthcare system should not be overwhelmed to avoid diverse adverse effects. Exploiting the fact that the severity of the disease increases considerably with age, the proposed control scheme protects high-risk individuals that mainly consist of the elderly. The protection of high-risk individuals reduces the average severity of the disease in the unprotected population, thereby substantially reducing mortality and avoiding the collapse of the healthcare system. Social acceptability (in terms of the resulting mortality) and feasibility (in terms of the healthcare system capacity) of the proposed herd immunity strategy are summarized into two respective, easily computable conditions by building on a simple susceptible–infected–recovered (SIR) model. For its parsimony, the proposed framework can provide a rule of thumb that applies to various populations for studying the viability of herd immunity strategies against COVID-19. For Japan, herd immunity may be developed by the considered control scheme ifand the severity rates of the disease are 1/10 times smaller than the previously reported value, although as high mortality as seasonal influenza is expected.

We study a parsimonious theory that synthesizes short-term traffic demand management (TDM) policies with long-term endogenous heterogeneities of demand. In a corridor network with multiple discrete bottlenecks, we study a model of system optimal assignment that integrates the short-term problem (departure time choice with tolling) and the long-term problem (job and residential location choice). For the short-term departure-time-choice equilibrium, under mild assumptions on schedule delay function, we derive analytical solutions under a first-best TDM scheme. Investigating properties of long-term equilibria, we found that the overall equilibrium pattern exhibits remarkable spatio-temporal sorting properties. It is further shown that a lack of integration of the short- and the long-term policy results in excessive investments for long-term road construction.

Harris and Wilson (1978)’s retail location model is one of the pioneering works in regional sciences. This model considers the combination of the “fast” and “slow” dynamics to describe spontaneous spatial pattern formation processes in the economic landscape. Although the model was proposed some time ago, its comparative static (bifurcation) properties have not yet been sufficiently explored. We employ a simple analytical approach developed by Akamatsu et al. (2012) to reveal previously unknown bifurcation properties of the model in a space with a large number of locations. It is analytically shown that the spatial structure’s evolutionary path exhibits a remarkable property, namely a “spatial period-doubling cascade,” which cannot be observed in the popular two-location setup. Furthermore, we discuss strong linkages between the model and “new economic geography” models in terms of their model structures and bifurcation properties. These results offer a new theoretical perspective for understanding agglomeration and spatial structure evolution.

This paper elucidates the bifurcation mechanism of an equidistant economy in spatial economics. To this end, we derive the rules of secondary and further bifurcations as a major theoretical contribution of this paper. Then we combine them with pre-existing results of direct bifurcation of the symmetric group [Formula: see text] [Elmhirst, 2004]. Particular attention is devoted to the existence of invariant solutions which retain their spatial distributions when the value of the bifurcation parameter changes. Invariant patterns of an equidistant economy under the replicator dynamics are obtained. The mechanism of bifurcations from these patterns is elucidated. The stability of bifurcating branches is analyzed to demonstrate that most of them are unstable immediately after bifurcation. Numerical analysis of spatial economic models confirms that almost all bifurcating branches are unstable. Direct bifurcating curves connect the curves of invariant solutions, thereby creating a mesh-like network, which appears as threads of warp and weft. The theoretical bifurcation mechanism and numerical examples of networks advanced herein might be of great assistance in the study of spatial economics.

Wheat often overproduces kernels when grown in favorable environments, resulting in low kernel weight with high kernel screenings. This indicates that photoassimilation after heading would not be sufficient to support the growth of a large number of kernels. The objective of this study was to examine the effects of crop thinning at heading (experiment 1) and double-row planting (compared with equidistant row spacing; experiment 2) on kernel weight and yield of Japanese wheat cultivars under different levels of soil fertility. In experiment 1, elimination of aboveground competition for radiation by thinning increased yield by up to 32%, mainly due to increased kernel weight. In experiment 2, double-row planting increased kernel weight significantly (by 4–10%) without yield loss by moderately suppressing maximum stem number (by 7–14%) and spike and kernel number (by up to 14%) under high fertility. In both experiments, the effect of crop thinning or row configuration on wheat yield and kernel weight was negligible under low fertility because of little competition for radiation. The results suggested that control of vegetative growth and kernel production would help avoid the shortage of assimilates for kernel growth in fertile environments. For further increasing wheat yield under favorable conditions in Japan, the appropriate crop management options (e.g., planting geometry) should be combined with the suitable varieties having a more communal ideotype (sparse tillering with upright posture) than a competitive phenotype (profuse tillering with lax posture) to enhance photoassimilation after heading.

In this study, we analyzed the actual amount of gasoline transported into the Tohoku region during the first month after the Great East Japan Earthquake. We found that: (1) the amount of gasoline supplied in the Tohoku region during the first two weeks was only 1/ 3 of the normal demand; (2) the shortage of supply in the first two weeks led to a huge “back-log of demand”; (3) it took four weeks for the backlog to be cleared and the lost (suppressed) demand during the period was equivalent to the amount of normal demand for 7 days; (4) the gaps between gasoline supply and demand in the Pacific coast areas were huge, compared with those in the Japan sea coast areas, while the gap in each prefecture of the Tohoku region was gradually reduced over time in the following order: Akita, Aomori, Iwate, Yamagata, and finally, Miyagi prefecture.

米デンプンのα-アミラーゼによる消化特性とグリセミック・インデックス(GI)を簡易に測定するため, 近赤外分光(NIR)法による推定精度について検討した. 検量線の作成は, 部分最小2乗法による回帰分析(PLS)で行った. NIR法による推定の実用性評価は, 推定値の標準誤差を検定試料の分布範囲と比較したEI法, および予測標準誤差を検定試料の標準偏差と比較したRPD法を用いて行った. 米デンプンの消化特性は3つのパラメーターを持った非線形式で表現した. そのパラメーターは, 加熱前処理に由来する分解物の割合(パラメーターa), α-アミラーゼの作用に由来する消化物の割合(同b), 消化速度(同c)である. GIはin vitroで評価したGI(EGI)を用いた. NIR法による簡易測定は, パラメーターcおよびEGIの推定において実用性があると判断された. その精度は遺伝資源にランクをつけるような一次スクリーニングに適用できるレベルであった. このことから, NIR法による簡易測定は, 米デンプンの消化速度が遅く, GIの低いイネ品種を選抜するのに有効と考えられた. また, 推定精度の向上のためには, イネの生態型や生産地によって試料を分けることが有効なことも示唆された.