Longitudinal river zonation in the tropics: examples of fish and caddisflies from endorheic Awash river, Ethiopia

Primary Research PaperSpecific concepts of fluvial ecology are well studied in riverine ecosystems of the temperate zone but poorly investigated in the Afrotropical region. Hence, we examined the longitudinal zonation of fish and adult caddisfly (Trichoptera) assemblages in the endorheic Awash River (1,250 km in length), Ethiopia. We expected that species assemblages are structured along environmental gradients, reflecting the pattern of large-scale freshwater ecoregions. We applied multivariate statistical methods to test for differences in spatial species assemblage structure and identified characteristic taxa of the observed biocoenoses by indicator species analyses. Fish and caddisfly assemblages were clustered into highland and lowland communities, following the freshwater ecoregions, but separated by an ecotone with highest biodiversity. Moreover, the caddisfly results suggest separating the heterogeneous highlands into a forested and a deforested zone. Surprisingly, the Awash drainage is rather species-poor: only 11 fish (1 endemic, 2 introduced) and 28 caddisfly species (8 new records for Ethiopia) were recorded from the mainstem and its major tributaries. Nevertheless, specialized species characterize the highland forests, whereas the lowlands primarily host geographically widely distributed species. This study showed that a combined approach of fish and caddisflies is a suitable method for assessing regional characteristics of fluvial ecosystems in the tropicsinfo:eu-repo/semantics/publishedVersio

Understanding effects of proximity on collaboration: Implications for technologies to support remote collaborative work

This chapter analyzes why computers and telecommunications have not created computcr-mediated work environments for collaboration that are as successful as physically shared environments. Our goals are, first, to identify the mechanisms by which proxin~ity makes cnl-laboration easier, concentrating on the way it facilitates interpersollal interaction and aware-ness; and second, to evaluate how current computer-mediated communication technologies provide or fail to provide the key benefits of proximity. We use a decompositional frame-work that examines how visibility, copresence, mobility, cotemporalitv and other affordances of media affect the important collaborative tasks of initiating conversation, establishing common ground, and maintaining awareness of potentially relevant changcs in the collabo-rative environment. Increasingly, collaborating with other people is as likely to take place over distance or time as it is face-to-face. An abundance of new communication technologies has been dcvcloped to mediate remote collaboration: e-mail, bulletin boards, instant messaging, document sharing, videoconferencing, awareness services, and others. Yet collaboration at a distance remains substantially harder to accomplish tha

Parameterization and Observability Analysis of Scalable Battery Clusters for Onboard Thermal Management

Although the battery surface temperature is commonly measured, the core temperature of a cell may be much higher hence more critical than the surface temperature. The core temperature of a battery, though usually unmeasured in commercial applications, can be estimated by an observer, based on a lumped-parameter battery thermal model and the measurement of the current and the surface temperature. Even with a closed loop observer based on the measured surface temperature, the accuracy of the core temperature estimation depends on the model parameters. For such purpose, an online parameterization methodology and an adaptive observer are designed for a cylindrical battery. The single cell thermal model is then scaled up to create a battery cluster model to investigate the temperature pattern of the cluster. The modeled thermal interconnections between cells include cell to cell heat conduction and convection to the surrounding coolant flow. An observability analysis is performed on the cluster before designing a closed loop observer for the pack. Based on the analysis, guidelines for determining the minimum number of required sensors and their exact locations are derived that guarantee the observability of all temperature states