Object Database Scalability for Scientific Workloads

We describe the PetaByte-scale computing challenges posed by the next generation of particle physics experiments, due to start operation in 2005. The computing models adopted by the experiments call for systems capable of handling sustained data acquisition rates of at least 100 MBytes/second into an Object Database, which will have to handle several PetaBytes of accumulated data per year. The systems will be used to schedule CPU intensive reconstruction and analysis tasks on the highly complex physics Object data which need then be served to clients located at universities and laboratories worldwide. We report on measurements with a prototype system that makes use of a 256 CPU HP Exemplar X Class machine running the Objectivity/DB database. Our results show excellent scalability for up to 240 simultaneous database clients, and aggregate I/O rates exceeding 150 Mbytes/second, indicating the viability of the computing models

Plant composition of three woodland communities of variable condition in the western Riverina, New South Wales, Australia

We examined differences in floristics among three regionally-threatened woodland communities in the western Riverina: Blackbox (Eucalyptus largiflorens), Bimble box-Pine (Eucalyptus populnea-Callitris glaucophylla) and Boree (Acacia pendula) between 2001 and 2004. Our aim was to examine possible relationships between the diversity and biomass of groundstorey vegetation, and remnant condition and rainfall both among communities and across years. The three woodland communities varied widely in their plant species composition, with only 22% of the 358 species common to all communities. Seven species, mainly exotic grasses and forbs, contributed 25% of the total cover across all sites and times. Blackbox communities had the greatest number of exotic and annual species. There were poor relationships between condition and diversity, richness, evenness or abundance of groundstorey plant species within 400 m2 quadrats. Overall, sites in better condition tended to support a greater cover of native plants and a lower cover of exotic plants (Blackbox only). There were only weak relationships between rainfall and biomass. The marked variation in species diversity in relation to changing seasonal conditions and within similar condition classes highlights the difficulties of developing benchmarks for separating the effects of management, and seasonal and longer-term climate change

Short article: When are moving images remembered better? Study–test congruence and the dynamic superiority effect

It has previously been shown that moving images are remembered better than static ones. In two experiments, we investigated the basis for this dynamic superiority effect. Participants studied scenes presented as a single static image, a sequence of still images, or a moving video clip, and 3 days later completed a recognition test in which familiar and novel scenes were presented in all three formats. We found a marked congruency effect: For a given study format, accuracy was highest when test items were shown in the same format. Neither the dynamic superiority effect nor the study–test congruency effect was affected by encoding (Experiment 1) or retrieval (Experiment 2) manipulations, suggesting that these effects are relatively impervious to strategic control. The results demonstrate that the spatio-temporal properties of complex, realistic scenes are preserved in long-term memory. </jats:p

Appropriate Accuracy of Models for Decision-Support Systems: Case Example for the Elbe River Basin

Given the growing complexity of water-resources management there will be an increasing need\ud for integrated tools to support policy analysis, communication, and research. A key aspect of the design is the\ud combination of process models from different scientific disciplines in an integrated system. In general these\ud models differ in sensitivity and accuracy, while non-linear and qualitative models can be present. The current\ud practice is that the preferences of the designers of a decision-support system, and practical considerations\ud such as data availability guide the selection of models and data. Due to a lack of clear scientific guidelines the\ud design becomes an ad-hoc process, depending on the case study at hand, while selected models can be overly\ud complex or too coarse for their purpose. Ideally, the design should allow for the ranking of selected\ud management measures according to the objectives set by end users, without being more complex than\ud necessary. De Kok and Wind [2003] refer to this approach as appropriate modeling. A good case example is\ud the ongoing pilot project aiming at the design of a decision-support system for the Elbe river basin. Four\ud functions are accounted for: navigability, floodplain ecology, flooding safety, and water quality. This paper\ud concerns the response of floodplain biotope types to river engineering works and changes in the flooding\ud frequency of the floodplains. The HBV-D conceptual rainfall-runoff model is used to simulate the impact of\ud climate and land use change on the discharge statistics. The question was raised how well this rainfall-runoff\ud model should be calibrated as compared to the observed discharge data. Sensitivity analyses indicate that a\ud value of R2 = 0.87 should be sufficient

Transistor performance of high-Tc three terminal devices based on carrier concentration modulation

Electric field effect devices and quasiparticle injection effect devices are good candidates for the realization of three terminal devices from high-T/sub c/ materials, since they take explicit advantage of the low carrier concentration in these compounds. We describe the fabrication and operation of both types of devices, and discuss their performance as transistor-like element

Psychometric Validation of the Dutch Version of the Promotive and Prohibitive Voice Scale

The aim of this three-study report was to validate the Dutch version of the promotive and prohibitive voice scale and to further embed the constructs of promotive and prohibitive voice within their nomological network. Promotive voice refers to the expression of suggestions for improving work practices, whereas prohibitive voice refers to the expression of concerns about practices and behaviors that are detrimental. In Study 1 (N = 121), confirmatory factor analyses (CFAs) provided evidence for the two-factor structure, which was replicated in the other two studies. In Study 2 (N(T1) = 209/N(T2) = 107), we investigated the convergent and discriminant validity of the promotive and prohibitive voice scale, and tested measurement invariance across gender and time. Results provided validity evidence, partial scalar invariance for gender, and scalar invariance across time. In Study 3 (N = 149), we expanded the nomological network of the promotive and prohibitive voice scales through their relationship with personal initiative, approach temperament, and risk propensity. Taken together, our results provide strong evidence for the validity of the Dutch version of the promotive and prohibitive voice scale