Sock discrimination for juvenile ayu, Plecoglossus altivelis altivelis from stomach of field-caught Japanese seabass, Lateolabrax japonicas in the Nuta River, Hiroshima Prefecture

広島県沼田川下流域でスズキに捕食された稚アユの由来判別を，耳石結晶化および耳石Sr/Ca比を指標に行った。稚アユ7個体のうち，3個体は耳石の結晶化が認められたことから人工放流種苗とした。正常な耳石を有していた4個体の耳石Sr/Ca比分析を行ったところ，3個体が人工放流種苗で，天然遡上は1個体となった。結局，稚アユ7個体の由来は，天然遡上が1個体で，6個体は放流された人工放流種苗と考えられた。耳石形状やSr/Ca比分析は，外敵に捕食された稚アユの由来判別に有効であると考えられた。Stock discrimination study for juvenile ayu, Plecoglossus altivelis altivelis from stomach of Japanese seabass, Lateolabrax japonicus in the Nuta River estuary was conducted using prey otolith morphology and Sr/Ca profiling. Out of 7 individuals, 3 individuals identified as hatchery-stock ayu that had crystallized otolith. Based on the Sr/Ca profiling for 4 individuals that have normal otolith, 1 individual was identified as an amohidromous form and 3 individuals were identified as hatchery-stock ayu. The results showed that otolith-based approches could provide insight into stock discrimination for even highly digested ayu that have lost all phenotypic characteristics

Insight into the migratory history using otolith Sr : Ca ratio of the anadromous masu salmon Oncorhynchus masou masou from the Tonegawa River

利根川上流域で採集した大型ヤマメ8個体の回遊性を耳石Sr:Ca比分析を用い検証した。その結果，3個体が降海型，5個体が非回遊型と推定された。最も上流で釣獲された検体（降海型）は，4つの堰を通過し，利根川河口から243km遡上していた。利根川には降海型サクラマスと非回遊型の大型ヤマメが生息しており，環境に応じて柔軟に回遊パターンを変化させている可能性が示唆された。The migratory histories of Oncorhynchus masou masou in the Tonegawa River were evaluated from the ontogenetic changes in otolith Sr:Ca ratios. We sampled 8 fish at 180-243 km upstream from the river mouth. Three fish were categorized as anadromous whereas five individual were categorized as nonanadromous life mode with the constantly low Sr:Ca ratios. Intraspecific variation in the migration modes recorded for O. masou masou suggest a plasticity strategy for anadromous behaviors

The migratory histories of the Cottus sp. (middle-egg type) in the Ota River

広島県太田川下流の高瀬堰周辺で採集されたカジカ中卵型の回遊性を，耳石Sr:Ca比分析によって確認した。高瀬堰周辺で採集した24個体の耳石Sr:Ca比は発育初期に高く，成長に従って減少した。よって，これらの個体は回遊型であると断定できた。一方，高瀬堰の上流に生息していた1個体は陸封型であった。カジカ中卵型は，回遊パターンに対して柔軟性を有することで環境に適応していると考えられた。The migratory histories of Cottus sp. (middle-egg type) were insighted from ontogenetic changes in otolith Sr:Ca ratios. We sampled 25 fish in the upstream and downstream of the Takase Weir in the Ota River. Twenty-four fish were categorized as amphidromous form whereas one individual caught in the upstream, showed landlocked life mode. Intraspecific variations in the migration pattern recorded for Cottus sp. (middle-egg type) suggest a plasticity strategy for diadromous behaviors

Broadband Infrastructure Deployment: The Role of Government Assistance

The potential economic importance of electronic commerce, and the role of broadband in supporting e-commerce, has increasingly led governments to place emphasis on facilitating access to broadband networks. To a large extent the emphasis has been on a range of policies aimed at supporting development and diffusion of high speed network capability in the local loop. Although broadband infrastructure deployment is in the process of development and the extent to which it will cover entire populations or geographic areas is still not clear, governments appear to want to accelerate the infrastructure investment. There is a wide range of government initiatives structured in different ways and their underlying justifications are often quite different. In this context, the main concern of this paper is to examine whether these initiatives are efficient in spurring broadband deployment and to what extent governments should be involved. The paper argues that government policies should ... Déploiement de l'infrastructure à large bande : Le rôle de l'aide publique Compte tenu du vaste potentiel économique du commerce électronique et du rôle que la large bande joue dans son développement, les pouvoirs publics s’attachent davantage à faciliter l’accès aux réseaux à large bande. L’accent est mis dans une large mesure sur le développement et la diffusion d’infrastructures haut débit dans la boucle locale. Bien que son déploiement soit toujours en cours et que l’on ignore encore dans quelle mesure elle couvrira l’ensemble de la population ou des zones géographiques, les pouvoirs publics semblent désireux d’accélérer les investissements dans l’infrastructure. Les initiatives des pouvoirs publics sont très variées, diversement structurées, et leurs justifications sont souvent très différentes. Dans ce contexte, le présent document cherche avant tout à définir si ces initiatives parviennent réellement à accélérer le déploiement de la large bande et dans quelle mesure le gouvernement devrait intervenir. Ce document avance également l’idée que les ...

A quantitative study on Japanese internet users\u27 awareness to information security: Necessity and importance of education and policy

In this paper, the authors examine whether or not there are differences of Japanese Internet users\u27 awareness to information security based on individual attributes by using analysis of variance based on non-parametric method. As a result, generally speaking, it is found that Japanese Internet users\u27 awareness to information security is different by individual attributes. Especially, the authors verify that the users who received the information security education would have rather higher recognition concerning countermeasures than other users including self-educated users. It is suggested that the information security education should be enhanced so that the users may appropriately take the information security countermeasures. In addition, the information security policy such as carrying out "e-net caravan" and "information security seminars" are effective in improving the users\u27 awareness on the information security in Japan.This work is licensed under a Creative Commons Licens