Information cartography: A proposed model for access to heterogeneous end-user databases.

Maps are among our best information systems. They require little documentation and are commonly used and understood. In contrast, many systems of classification seem to lack this acceptance and ease ofuse. Anecdotal evidence suggests that this is particularly true of the way collections of databases are classified for online browsing on library Web sites. This paper argues that some ofthe characteristics that make maps easily usable can be applied to collections of databases. Those characteristics include logical grouping of information, the ability to move smoothly between levels ofdata, and consistent amounts of data at different levels of representation

Converting a Controlled Vocabulary into an Ontology: the Case of GEM

The prevalance of digital information raised issues regarding the suitability of conventional library tools for organizing information. The multi-dimensionality of digital resources requires a more versatile and flexible representation to accommodate intelligent information representation and retrieval. Ontologies are used as a solution to such issues in many application domains, mainly due to their ability explicitly to specify the semantics and relations and to express them in a computer understandable language. Conventional knowledge organization tools such as classifications and thesauri resemble ontologies in a way that they define concepts and relationships in a systematic manner, but they are less expressive than ontologies when it comes to machine language. This paper used the controlled vocabulary at the Gateway to Educational Materials (GEM) as an example to address the issues in representing digital resources. The theoretical and methodological framework in this paper serves as the rationale and guideline for converting the GEM controlled vocabulary into an ontology. Compared to the original semantic model of GEM controlled vocabulary, the major difference between the two models lies in the values added through deeper semantics in describing digital objects, both conceptually and relationally

Assessing the ecological health of estuaries in southwest Australia

Southwestern Australia experiences a Mediterranean climate and its estuaries are at risk from eutrophication because of a limited oceanic tidal range, constricted or barred ocean entrances, shallow estuarine basins, extensive agricultural clearing and draining in catchments, fertilized sandy coastal plain soils with limited phosphorus sorption capacity, large inland catchments with little vegetative cover at the onset of winter rains and widespread erosion. Elevated nutrient and sediment loads to southwest estuaries have caused disruption of ecosystem processes in some estuaries including seagrass loss, macroalgal and phytoplankton nuisance, and anoxia. To investigate estuarine health in the southwest, five sites in each of eight estuaries and five sites at a marine reference location (45 sites), were investigated using a range of physical, chemical and biological indicators. Water and sediment nutrient concentrations were determined at each site, together with an assessment of the community structure of phytoplankton, and benthic macroinvertebrates. Historical water quality information was evaluated to provide perspective. Despite some past analytical uncertainty, there appears to have been a significant increase in median total phosphorus concentrations in both the upper Swan (12 to 90 µg L -1 ), and Peel-Harvey estuaries (15 to 70 µg L-1), from 1945 to 1995. Surface salinity transects in summer 1995 typified classical, lagoonal and reverse estuaries, depending on basin morphology, marine contact and runoff volumes. Summer N, P and chlorophyll a concentrations in estuarine waters were correlated and were consistent with the extent of agricultural development particularly for sandy coastal catchments. Phytoplankton species diversity (evenness) was inversely related to total cell densities and estuarine nutrient status. Macro-invertebrate diversity (evenness) was inversely related to abundance. The proportion of cyanophyte and dinoflagellate cells in phytoplankton communities was high for some diverse pristine sites with low levels of chlorophyll a, low for all sites with moderate levels of chlorophyll a, and high for some sites with high levels of chlorophyll a. The suite of environmental indicators evaluated here collectively provided a useful indicator of estuarine health

The effects of a hydrogen-rich ground cover on cosmogenic thermal neutrons:Implications for exposure dating

We present results of thermal neutron flux measurements in experimental granite piles that were tailored to study the effect of hydrogen-rich covers on that flux. We find that hydrogen-rich covers (polyethylene, water), used as proxies for snow, dead and/or live plant matter, increase the thermal neutron flux in an underlying rock surface significantly, as compared to the state without cover. The rock serves as the main source for thermal neutrons, the hydrogen-rich cover as a neutron reflector. In situations where the thickness of such a cover would be negligible in terms of high-energy neutron (>10 MeV) attenuation, e.g. 2-3 cm water equivalent cover, a significant enhancement of the thermal neutron flux (factor >2.5 +/- 0.5) can be achieved. This increase is made up of three components (Masarik et al., 2007): (1) reflected thermal neutrons (albedo neutrons), (2) moderated fast neutrons from the ground, and (3) moderated fast neutrons from the atmospheric cascade (Masarik et al., 2007). The higher thermal neutron flux increases the production rates of those cosmogenic nuclides that have a significant thermal neutron production pathway (He-3, Cl-36, Ca-41) Ignoring this effect in situations where target nuclei (Li-6, Cl-36, Ca-40) are abundant will severely underestimate production rates. The effect of hydrogenrich ground cover on the thermal neutron flux has the potential to be used for studies that are aimed at reconstructing the persistence of past plant/snow cover. Isotopic ratios of spallogenic versus predominantly thermal neutron produced nuclides, would reveal the presence or absence of hydrogen-rich cover in the past as compared to the present-day situation. (C) 2013 Elsevier B.V. All rights reserved