The Ecology of Parafluvial Ponds on a Salmon River

Parafluvial ponds are discrete lentic habitats embedded in the alluvia of gravel bed rivers that are formed by flooding and persist in relation to floodplain geohydrology. On the expansive flood plains of the Kwethluk River, I observed thousands of juvenile salmon apparently trapped by surface disconnection of the ponds from the river. I was interested in whether the salmon could survive until flooding reconnected the ponds to the river. I sampled ponds along the river corridor to describe habitat quantity and juvenile salmon presence, growth, and diet. Furthermore, I looked at pond hydrology, temperature regime, and the role groundwater plays in pond ecology. Total ponds along the river corridor (145km) varied in space and time as the season progressed from spring (n=81), summer (n=166), and fall (n=175) revealing that they were persistent and ubiquitous from the headwaters to the lower river. Five fish species were found, of which three were Pacific salmon, and 51 invertebrate taxa with 15 unique to ponds. Salmon, primarily coho (Oncorhyncus kisutch), were most abundant in ponds. Fish populations ranged from 0 to 772 in the 12 main study ponds. The mean area of ponds was small (44.1m2), but this did not inhibit growth and high survival. Coho consistently fed on small invertebrates, predominantly Chironomids and Cladocera, and growth rates were as high as 1.35mm per week. Not only were fish able to grow, but population estimates were similar throughout the season indicating low mortality, and the annual bimodal occurrence of floods allowed juvenile salmon to actively move in and out of ponds. I concluded that juvenile salmon proactively occupy the shallow environments of parafluvial ponds because they function as nursery habitat that is commonly available on natural floodplain rivers like the Kwethluk

The evolution of regional productivity disparities in the European Union, 1975-2000

The aim of this paper is to assess the evolution of regional productivity disparities in the European Union. Using a sample of 205 regions and 8 sectors on the 1975-2000 period, we use Esteban’s (2000) shift-share analysis to investigate the extent to which the existing interregional inequalities in productivity can be attributed to differences in sectoral composition between regions and/or to uniform productivity gaps across sectors. After a specification search on the bivariate functional forms that relate productivity differentials to their shift-share decomposition, the difference between regional and EU average productivity is regressed on the three shift-share components: industry-mix, differential and allocative (i.e. the covariance between the first two components). In that purpose, spatial seemingly unrelated (SUR) regressions are carried out to study the evolution of the impact of the components on the productivity gap over time, while allowing for intertemporal covariance. Moreover, spatial autocorrelation is also included in the SUR regressions, and its evolution over the period is analyzed. Results indicate that both spatio-temporal dependencies are essential in model specification.European regions, productivity disparities, spatial autocorrelation, SUR

Study and optimization of ion-irradiated High-Tc Josephson nanoJunctions by Monte Carlo simulations

High Tc Josephson nanoJunctions (HTc JnJ) made by ion irradiation have remarkable properties for technological applications. However, the spread in their electrical characteristics increases with the ion dose. We present a simple model to explain the JnJ inhomogeneities, which accounts quantitatively for experimental data. The spread in the slit's width of the irradiation mask is the limiting factor.Monte Carlo simulations have been performed using different irradiation conditions to study their influence on the spread of the JnJ charcateristics. A "universal" behavior has been evidenced, which allows to propose new strategies to optimize JnJ reproducibility.Comment: 14 pages, 6 Figures. accepted in Journal of Applied Physic

Smart Conversational Agents for Reminiscence

In this paper we describe the requirements and early system design for a smart conversational agent that can assist older adults in the reminiscence process. The practice of reminiscence has well documented benefits for the mental, social and emotional well-being of older adults. However, the technology support, valuable in many different ways, is still limited in terms of need of co-located human presence, data collection capabilities, and ability to support sustained engagement, thus missing key opportunities to improve care practices, facilitate social interactions, and bring the reminiscence practice closer to those with less opportunities to engage in co-located sessions with a (trained) companion. We discuss conversational agents and cognitive services as the platform for building the next generation of reminiscence applications, and introduce the concept application of a smart reminiscence agent

Dietary ecology of mixed-feeding antelopes in the Omo-Turkana basin during the Plio-Pleistocene: a tool to investigate hominin palaeo-environments.

To assess whether detailed studies of the dietary ecology of mixed-feeding antelope species could be used to investigate hominin palaeo-environments in the Omo-Turkana basin during the Plio-Pleistocene (3.5-1.6 Ma), a detailed study of the dietary ecology of mixed-feeding antelopes was proposed. This research focused on the diets of the impala (genus Aepyceros) and the springbok (genus Antidorcas), whose extant relatives demonstrate a high dietary plasticity. The dietary ecology of these taxa was evaluated through stable carbon and oxygen isotope, mesowear and dental microwear textural analyses. To provide more tools to interpret fossil evidence, predictive models were tested to study the relationship between land cover and dietary behaviours of modern populations. The high variability of stable carbon isotope values observed across modern impala specimens and the wide range of habitat types they were associated with showed that impalas tend to rely heavily on palatable grasses and forbs, suggesting a preference for herbaceous plants. The diet of modern impalas therefore does not always reflect the vegetation types prevailing in their environments, as availability of their preferred foods can be influenced by local year-round land cover patterns and by seasonal fluctuations in climate. However, the predictions generated for fossil Aepyceros samples for the Omo-Turkana basin were consistent with previous palaeo- environmental studies for this region, demonstrating the potential of this method and the relevance of using these taxa as palaeo-environmental indicators. Significant differences in dietary ecology were observed for the studied taxa when comparing assemblages from different fossil localities, as well as when comparing assemblages between members. Results suggested the presence, across all three fossil localities of the Omo-Turkana basin, of long-lived mosaic habitats, which could have supported a high diversity of mammalian taxa with varying ecological requirements. Results confirmed previous studies which suggested patterns of grassland expansion and increased habitat fragmentation in the region from ~2.0 Ma, as well as an increase in seasonal and interannual rainfall variability between 2.27 and 1.9 Ma. Such conditions have been previously hypothesized to have influenced local faunal biodiversity in the region, adding selective pressures associated with seasonal changes in resources abundance and distribution, acting, in turn, as an additional driver of hominin evolution

Grafting the Way to the Systemic Silencing Signal in Plants

Grafting is a powerful but complex means to study the spread of RNA silencin