3ibook: a user interface metaphor for children-analysis, design and evaluation

计算的无处不在使得计算机已成为儿童学习、娱乐的工具,而设计和开发面向儿童的互动系统的主要瓶颈在于如何设计界面隐喻,使其更易于儿童理锯和使用.通过对现有界面隐喻的分析,针对儿童的认知特征提出一个基于儿童卡通读物的界面隐喻--3IBook,并从结构设计、操作设计和实效设计3个方面描述3IBook的设计特征;同时分析了基于3IBook的交互模型.最后通过一个互动游戏系统的实现来评估该隐喻在面向儿童的交互式软件中应用的合理性和有效性

溪流大型底栖动物栖息地适合度模型的构建与河道内环境流量研究——以三峡库区香溪河为例

基于对香溪河河流生态系统的多年研究，以该流域河流大型底栖动物最优势类群四节蜉为指示生物，建立了我国大陆地区第一个基于长期的连续的野外现场实测数据的水生生物栖息地适合度模型（habitat suitability model，HSM）．为保护河流生态系统结构和功能的完整性，文中将河道内环境流量分为3个层次，即河道内最小需水量、最小环境流量和适宜环境流量，并利用水文法和加权可利用面积法（weighted usable area，WUA）分别构建了这3个层次的河道内环境流量的计算模型．结果表明：香溪河的最小需水量为Tennant法中描述为差或最小状态的流量（即0．615m^3·s^-1），为保护河流生态系统健康、维系河道景观多样性，应将多年平均流量的42．91％（即2．639m^3·s^-1）作为研究地点的适宜环境流量．综合考虑水文和生物因素，从3个层次确定了河道内环境流量，可以为香溪河水资源的合理配置和综合管理提供技术支持，同时为较准确地计算河道内最小环境流量提供探索性研究

Breaking the stranglehold of striga

Dipping maize seeds in a very small amount of herbicide blocks the ability of Striga hermonthica to parasitize and kill crops. Experiments over the past two years m Kenya have shown that dipping seeds in the herbicide imazapyr can triple the yield of maize. The results of the trial were announced earlier in the year at the Sixth Parasitic Weed Symposium in Cordoba, Spain. The technique has been developed by researchers at the Kenyan Agricultural Research Institute (KARI) at Kisumu, Kenya, together with plant geneticists from the Weizman Institute of Science in Rehovot, Israel. Currently, the technique is based on using a herbicide-resistant strain of maize developed by an American seed company, Pioneer International. Pioneers strain of maize can withstand herbicides which block the action of an enzyme called ace to lactate synthase . Without this enzyme, striga is unable to make vital amino acids, and dies. Trials showed that, on average, a plot of treated seed yielded almost 3.5 times as much maize per plot compared to plots of untreated seeds which had five times as much striga growing in them as the treated plots. As the dipped seeds grow, the herbicide diffuses into the growing tissue and surrounding soil, killing the striga before it can get a hold. By the time the maize is harvested the herbicide in the soil has broken down. The use of this seed-dipping technique cuts out the need for potentially harmful spraying and eliminates the buildup of residues in the soil. Additionally, the cost of using such small quantities of herbicide is so little that even the poorest subsistence farmer could afford the technology. Just 15 grams of herbicide costing $5 is enough to treat one hectare, and could bring a farmer an extra$100 of income per hectare in improved yields. At present this Pioneer strain of maize, which was developed for use in the US, is susceptible to African fungi and viruses. The KARI researchers are now crossing the Pioneer strain with African varieties to produce a herbicide-resistant maize that is suited to local conditions. George Odhiambo and Gordon Abayo Kenyan Agricultural Research Institute Kisumu, KENYADipping maize seeds in a very small amount of herbicide blocks the ability of Striga hermonthica to parasitize and kill crops. Experiments over the past two years m Kenya have shown that dipping seeds in the herbicide imazapyr can triple the yield..

香溪河流域水体环境因子研究

基于香溪河及其三大支流古夫河、高岚河与九冲河的8年监测数据,对该流域水体的环境因子及其时空动态进行了比较分析。结果显示,香溪河流域的水体呈中性偏弱碱性,属于中等硬度水,水体溶解氧丰富,还原性物质以及氯化物水平不高,具有较强的缓冲能力。多数环境因子具有明显的季节变化,而年际变化规律不显著。香溪河流域水体的主要营养元素氮含量较高,并以有城镇影响的古夫河为最;高岚河由于受到生活污水与农业活动的影响,水质相对较差;香溪河的磷污染严重;森林覆盖率较高的九冲河的水质最佳。在香溪河流域,氮主要以面源污染的方式进入河道

三峡水库香溪河库湾主要营养盐的入库动态

基于香溪河及其主要支流高岚河的5a监测数据,估算三峡水库香溪河库湾氮磷营养盐的入库通量,并分析了氮磷营养盐的浓度及其通量的逐月动态。研究发现,每年大约有1623.49t总氮和331.85t总磷汇入香溪河库湾,其中,香溪河贡献了68.50%的总氮和91.74%的总磷。在这两条河流中,溶解无机氮是氮的主要存在形式;氮通量表现出夏季7月份偏高、春秋季次之、冬季较低的规律;面源污染是氮进入河道的主要途径。磷酸盐是香溪河磷的主要存在形式,而高岚河磷酸盐的含量则较低;香溪河磷通量的月均波动规律不明显,高岚河磷通量的