Finding Science with Science: Evaluating a Domain and Scientific Ontology User Interface for the Discovery of Scientific Resources

Current approaches to the discovery of scientific resources (publications, data sets and web services) are dominated by keyword search. These approaches do not allow scientists to search on the deeper semantics of scientific resources, or to discover resources on the basis of the scientific approaches taken. This article evaluates a user interface that allows users to discover scientific resources through structured knowledge in the form of ontologies describing the domain and the scientific knowledge inherent within the scientific resource, and also through informal user tags. These combined capabilities provide scientists with new and powerful options for resource discovery. A qualitative user evaluation explored how scientists felt about the approach for resource discovery in the context of their scientific work. The study showed that marine scientists were enthusiastic about the capabilities of such an approach and appreciated the ability to browse the visual structure of the knowledge and query on scientific method but, overall, preferred the use of tags over ontologies. The exploratory nature of the user study was used to identify future directions for such improvements.     

Comparison of Multimission Altimetric Sea-Surface Heights with Tide Gauge Observations in the Southern Baltic Sea

One possible technique to validate the observations of altimeter missions is the comparison with sea-surface heights measured by tide gauges. In our investigation, we compared observations of the two tide gauge stations, Sassnitz and Warnemünde, which are located at the southern coast of the Baltic Sea, with sea-surface heights obtained from the altimeter missions Geosat, ERS-1, ERS-2, and TOPEX/Poseidon. For this purpose, the compared sea-surface heights were related to a common reference system and extrapolated to a common location. GPS observations, leveling data, regional geoid information, sea-surface topography, and postglacial rebound were included in the analysis. Considering the uncertainties of all model components, a more reliable estimation of the error budget (source, type, and magnitude of the errors) was performed. The obtained absolute altimeter biases are (-243 - 32) mm for Geosat, (467 - 19) mm for ERS-1, (76 - 19) mm for ERS-2, and (13 - 18) mm for TOPEX.     

Simulating CO<Subscript>2</Subscript> transport into the ocean from a CO<Subscript>2</Subscript> lake at the seafloor using a <Emphasis Type="Italic">z</Emphasis>- and a <Emphasis Type="Italic">σ</Emphasis>-coordinate model

The ocean takes up approximately 2 GT carbon per year due to the enhanced CO₂ concentrations in the atmosphere. Several options have been suggested in order to reduce the emissions of CO₂ into the atmosphere, and among these are CO₂ storage in the deep ocean. Topographic effects of dissolution and transport from a CO₂ lake located at 3,000-m depth have been studied using the z-coordinate model Massachusetts Institute of Technology general circulation model (MITgcm) and the σ-coordinate model Bergen ocean model (BOM). Both models have been coupled with the general ocean turbulence model (GOTM) in order to account for vertical subgrid processes. The chosen vertical turbulence mixing scheme includes the damping effect from stable stratification on the turbulence intensity. Three different topographic scenarios are presented: a flat bottom and the CO₂ lake placed within a trench with depths of 10 and 20 m. The flat case scenario gives good correlation with previous numerical studies of dissolution from a CO₂ lake. When topography is introduced, it is shown that the z-coordinate model and the σ-coordinate model give different circulation patterns in the trench. This leads to different dissolution rates, 0.1 μmol cm^− 2 s^− 1 for the scenario of a 20-m-deep trench using BOM and 0.005–0.02 μmol cm^− 2 s^− 1 for the same scenario using the MITgcm. The study is also relevant for leakages of CO₂ stored in geological formations and to the ocean.     

Predicting ground water nitrate concentration from land use

Ground water nitrate concentrations on Nantucket Island, Massachusetts, were analyzed to assess the effects of land use on ground water quality. Exploratory data analysis was applied to historic ground water nitrate concentrations to determine spatial and temporal trends. Maximum likelihood Tobit and logistic regression analyses of explanatory variables that characterize land use within a 1000-foot radius of each well were used to develop predictive equations for nitrate concentration at 69 wells. The results demonstrate that historic nitrate concentrations downgradient from agricultural land are significantly higher than nitrate concentrations elsewhere. Tobit regression results demonstrate that the number of septic tanks and the percentages of forest, undeveloped, and high-density residential land within a 1000-foot radius of a well are reliable predictors of nitrate concentration in ground water. Similarly, logistic regression revealed that the percentages of forest, undeveloped, and low-density residential land are good indicators of ground water nitrate concentration > 2 mg/L. The methodology and results outlined here provide a useful tool for land managers in communities with shallow water tables overlain with highly permeable materials to evaluate potential effects of development on ground water quality.     

The 6dF Galaxy Survey: final redshift release (DR3) and southern large-scale structures

We report the final redshift release of the 6dF Galaxy Survey (6dFGS), a combined redshift and peculiar velocity survey over the southern sky  (| b | > 10°)  . Its 136 304 spectra have yielded 110 256 new extragalactic redshifts and a new catalogue of 125 071 galaxies making near-complete samples with  ( K , H , J , r _F, b _J) ≤ (12.65, 12.95, 13.75, 15.60, 16.75)  . The median redshift of the survey is 0.053. Survey data, including images, spectra, photometry and redshifts, are available through an online data base. We describe changes to the information in the data base since earlier interim data releases. Future releases will include velocity dispersions, distances and peculiar velocities for the brightest early-type galaxies, comprising about 10 per cent of the sample. Here we provide redshift maps of the southern local Universe with   z ≤ 0.1  , showing nearby large-scale structures in hitherto unseen detail. A number of regions known previously to have a paucity of galaxies are confirmed as significantly underdense regions. The URL of the 6dFGS data base is http://www-wfau.roe.ac.uk/6dFGS .     

Formation and evolution of carbonate chimneys at the Lost City Hydrothermal Field

The Lost City Hydrothermal Field at 30°N, near the Mid-Atlantic Ridge, is an off-axis, moderate temperature, high-pH (9-10.8), serpentinite-hosted vent system. The field is hosted on ∼1.5 Ma crust, near the summit of the Atlantis Massif. Within the field, actively venting carbonate chimneys tower up to 60 m above the seafloor, making them the tallest vent structures known. The chemistry of the chimneys and vent fluids is controlled by serpentinization reactions between seawater and underlying peridotite. Mixing of <40-91 °C calcium-rich vent fluids with seawater results in the precipitation of variable mixtures of aragonite, calcite, and brucite. The resultant deposits range from tall, graceful pinnacles to fragile flanges and delicate precipitates that grow outward from fissures in the bedrock. In this study, mineralogy, petrographic analyses, major and trace element concentrations, and Sr isotopic compositions are used to propose a model for the growth and chemical evolution of carbonate chimneys in a serpentinite-hosted environment. Our results show that nascent chimneys are characterized by a porous, interlacing network of aragonite, and brucite minerals that form extremely fragile structures. The chemistry of these young deposits is characterized by ∼10 wt% Ca and up to 27 wt% Mg, extremely low trace metal concentrations, and ⁸⁷Sr/⁸⁶Sr isotope ratios near 0.70760. During aging of the chimneys, progressive reactions with seawater result in the dissolution of brucite, the conversion of aragonite to calcite, and infilling of pore spaces with calcite. The oldest chimneys are dominated by calcite, with bulk rock values of up to 36 wt% Ca and <1 wt% Mg. These older structures contain higher concentrations of trace metals (e.g., Mn and Ti), and have Sr isotope ratios near seawater values (0.70908). Exposed ultramafic rocks are prevalent along the Mid-Atlantic, Arctic, and Indian Ocean ridge networks and it is likely that other Lost City-type systems exist.