新潟県の古典型ツツガムシ病－有毒地の形成に関して－| 新潟県の古典型ツツガムシ病－有毒地の形成に関して－ |
| 仲川隆夫 |
| 新潟県新潟平野の信濃川と阿賀野川，六日町盆地の魚野川，秋田県横手盆地の雄物川の流域では，1960 年代まで，アカツツガムシ（Leptotrombidium akamushi）が媒介する古典型ツツガムシ病の患者が毎夏発生していた．病原体であるリケッチア（Orientia tsutsugamushi）を保有するアカツツガムシが生息する堤外地を主とした地点は，有毒地と呼ばれていた．それらの地点の土地条件を，1910 年代測量の5 万分の1 地形図（大日本帝国陸地測量部）の読図と現地調査によって調べ，有毒地の形成に関わった要因を検討した．有毒地が堤外地に形成されるためには，①平水位より1m～3m 高く，軽微な出水では冠水しない，②砂質粘土や粘土質砂からなり植物が繁茂していることに加え，③アカツツガムシや本来の宿主であるハタネズミが安定的に生息するためにある程度の面積をもつ，④肥沃な土壌が運ばれ植物が繁茂するために大規模な出水時に短期間冠水すること，が必要と考えられる． |
| Classical Tsutsugamushi disease, Trombiculid mite, "Yuudokuchi" (noxious area), land condition, formation, Northeast Japan |
| The gemstone and jewelry industry in Thailand: a brief report on the changes and challenges from upstream to downstream |
| Rouay LIMSUWAN |
| Thai’s gemstone and jewelry industry historically has an important role
in the economy of the country. This highly competitive industry has observed
changes as well as problems from upstream, through midstream to downstream. “Upstream industry” means mining to produce crude gem-bearing ore. This business environment is tough because the mining law and relevant regulations are strict in terms of social and environmental responsibility. In addition mining companies are facing a shortage of resources because of the numerous large scale mechanized operations that have arrived over the past two decades which mined out the most fertile areas of mineral deposits. “Midstream industry” means value adding to improve the appearance of crude gem-bearing ore by heat treatment and lapidary. The business situation here is contradictory and confused by the fact that many products have been treated using complicated and non-standard techniques involving chemical additives. The true openness and transparency of basic information about the treatments is important in order to guard the credibility of the industry. “Downstream industry” means trade and marketing of the products. Here, business was disturbed not only by serious shortages of raw materials but also by the prevalence of treated/enhanced and counterfeit gems and jewelry products on the market. Consequently, consumers should seek to receive certificates or warrantees for their products issued by a world class standard identification institute before money changes hands. Additionally, restrictions on trade launched by other trading countries often stifled business. Survival of the downstream industry channels depends on how they respond to these changes and problems and whether they can beat the global competition. |
| gem gravels, gem minerals, jewelry products, mining, value adding, heat treatment, lapidary, Thailand |