Designing Improved Sediment Transport Visualizations

Monitoring, or more commonly, modeling of sediment transport in the coastal environment is a critical task with relevance to coastline stability, beach erosion, tracking environmental contaminants, and safety of navigation. Increased intensity and regularity of storms such as Superstorm Sandy heighten the importance of our understanding of sediment transport processes. A weakness of current modeling capabilities is the ability to easily visualize the result in an intuitive manner. Many of the available visualization software packages display only a single variable at once, usually as a two-dimensional, plan-view cross-section. With such limited display capabilities, sophisticated 3D models are undermined in both the interpretation of results and dissemination of information to the public. Here we explore a subset of existing modeling capabilities (specifically, modeling scour around man-made structures) and visualization solutions, examine their shortcomings and present a design for a 4D visualization for sediment transport studies that is based on perceptually-focused data visualization research and recent and ongoing developments in multivariate displays. Vector and scalar fields are co-displayed, yet kept independently identifiable utilizing human perception\u27s separation of color, texture, and motion. Bathymetry, sediment grain-size distribution, and forcing hydrodynamics are a subset of the variables investigated for simultaneous representation. Direct interaction with field data is tested to support rapid validation of sediment transport model results. Our goal is a tight integration of both simulated data and real world observations to support analysis and simulation of the impact of major sediment transport events such as hurricanes. We unite modeled results and field observations within a geodatabase designed as an application schema of the Arc Marine Data Model. Our real-world focus is on the Redbird Artificial Reef Site, roughly 18 nautical miles offshor- Delaware Bay, Delaware, where repeated surveys have identified active scour and bedform migration in 27 m water depth amongst the more than 900 deliberately sunken subway cars and vessels. Coincidently collected high-resolution multibeam bathymetry, backscatter, and side-scan sonar data from surface and autonomous underwater vehicle (AUV) systems along with complementary sub-bottom, grab sample, bottom imagery, and wave and current (via ADCP) datasets provide the basis for analysis. This site is particularly attractive due to overlap with the Delaware Bay Operational Forecast System (DBOFS), a model that provides historical and forecast oceanographic data that can be tested in hindcast against significant changes observed at the site during Superstorm Sandy and in predicting future changes through small-scale modeling around the individual reef objects

L'élevage bovin allaitant aux Philippines : réalisation d'une typologie des systèmes d'élevage sur l'Ile de Mindanao

La faible productivité des animaux est décrite comme une des causes principales des difficultés de l'élevage bovin sur Mindanao comme sur le reste de l'archipel des philippines. Dans le cadre d'un projet étranger de soutien à la filière, conduit dans le sud de l'île, une typologie des systèmes d'élevage des bovins allaitants s'est avérée nécessaire pour mieux cerner les conditions techniques, sociales et économiques de cette production au niveau des petits éleveurs. Cette typologie s'est effectuée sur la base de 136 entretiens avec les éleveurs, réalisés de mai à juillet 2001 au nord et au sud de Mindanao et fomalisés par des questionnaires d'enquête. Les informations obtenues ont permis une première description générale des pratiques d'élevage. Une analyse factorielle des correspondances multiples suivie d'une classification hiérarchique ascendante a été menée. Elles débouchent sur 4 typologies peu corrélées, une typologie des éleveurs et de leurs ressources foncières, une typologie des structures de troupeau, une typologie des conduites d'élevage et une dernière typologie des résultats technico-économiques. Pour chacune, 4 grands groupes ont pu être identifiés. Les principaux facteurs discriminants sont respectivement les ressources financières, l'effectif du troupeau, l'utilisation du pâturage et des intrants alimentaires, les modalités de vente. Les principales contraintes de production identifiées sont les objectifs et les conduites d'élevage

Effect of lattice volume and strain on the conductivity of BaCeY-oxide ceramic proton conductors

In-situ electrochemical impedance spectroscopy was used to study the effect of lattice volume and strain on the proton conductivity of the yttrium-doped barium cerate proton conductor by applying the hydrostatic pressure up to 1.25 GPa. An increase from 0.62 eV to 0.73 eV in the activation energy of the bulk conductivity was found with increasing pressure during a unit cell volume change of 0.7%, confirming a previously suggested correlation between lattice volume and proton diffusivity in the crystal lattice. One strategy worth trying in the future development of the ceramic proton conductors could be to expand the lattice and potentially lower the activation energy under tensile strain

Gravitational birefringence and an exotic formula for redshift

16 pages, 2 figuresInternational audienceWe compute the birefringence of light in curved Robertson-Walker spacetimes and propose an exotic formula for redshift based on the internal structure of the spinning photon. We then use the Hubble diagram of supernovae to test this formula

The Impact of Typical Survey Weighting Adjustments on the Design Effect: A Case Study

In survey sampling, the final sample weight assigned to each sampled unit reflects different steps of weighting adjustments such as frame integration, nonresponse and calibration. The analysis of the design effects for each of these adjustments casts light on their effects on the precision of survey estimates. In this paper, we limit our scope to the Canadian Community Health Survey (CCHS), briefly describe the weighting process of this survey and examine design effects at different steps of the weighting process to quantify how the overall variability in estimates can be attributed to the complex survey design and to each of the individual adjustments in the weighting process. As expected, the results suggest that the use of unequal person-selection probabilities and the nonresponse adjustment have the most negative impact on the design effect of the CCHS while calibration and winsorization decrease the design effect and improve the precision of the estimates

Chains of modular elements and shellability

Let L be a lattice admitting a left-modular chain of length r, not necessarily maximal. We show that if either L is graded or the chain is modular, then the (r-2)-skeleton of L is vertex-decomposable (hence shellable). This proves a conjecture of Hersh. Under certain circumstances, we can find shellings of higher skeleta. For instance, if the left-modular chain consists of every other element of some maximum length chain, then L itself is shellable. We apply these results to give a new characterization of finite solvable groups in terms of the topology of subgroup lattices. Our main tool relaxes the conditions for an EL-labeling, allowing multiple ascending chains as long as they are lexicographically before non-ascending chains. We extend results from the theory of EL-shellable posets to such labelings. The shellability of certain skeleta is one such result. Another is that a poset with such a labeling is homotopy equivalent (by discrete Morse theory) to a cell complex with cells in correspondence to weakly descending chains.Comment: 20 pages, 1 figure; v2 has minor fixes; v3 corrects the technical lemma in Section 4, and improves the exposition throughou