Airborne detection of ecosystem responses to an extreme event: Phytoplankton displacement and abundance after hurricane induced flooding in the Pamlico-Albemarle Sound system,North Carolina

Airborne laser-induced fluorescence measurements were used to detect and monitor ecosystem wide changes in the distribution and concentration of chlorophyll biomass and colored dissolved organic matter in the Pamlico-Albemarle Sound system, North Carolina, U.S., following massive flooding caused by a series of three hurricanes in the late summer of 1999. These high-resolution data provided a significantly more detailed representation of the overall changes occurring in the system than could have been achieved by synoptic sampling from any other platform. The response time for the distribution of chlorophyll biomass to resume pre-flood conditions was used as a measure of ecosystem stability. Chlorophyll biomass patterns were reestablished within four mo of the flooding, whereas higher chlorophylla biomass concentrations persisted for approximately 6 mo. The primary trophic level in the Pamlico-Albemarle Sound system returned to equilibrium in less than a year of a major perturbation.     

The uniqueness of the Practical Salinity Scale (1978): testing thescale with natural seawaters

The scale provides a precisely defined, unambiguous method that is universally applicable to all waters for determining the practical salinity from measurements of conductivity, temperature, and pressure. In the terminology of standards, it is highly desirable to have a scale that is also unique. The authors questioned whether measurements performed on a particular water sample at different temperatures would lead to the same value of practical salinity. They have investigated this problem by examining the behavior of natural seawaters from several oceans and conclude that the PSS provides a unique scale for salinity measurements for these waters within the bounds ±0.001 in salinity     

CLASSIFICATION OF TWENTY-SIX CHONDRITES FROM ROOSEVELT COUNTY,NEW MEXICO

Twenty-six of the fifty-seven stone meteorites listed in Huss (1979) from Roosevelt County, New Mexico, have been classified in the present study. Microprobe analyses indicate 15 H type, 9 L type and 2 LL type chondrites. Based on compositional, textural, and locational comparisons, as many as 10 chondrites may be paired to three distinct falls.     

ANOTHER VIEW OF THE SIXTEEN-MILLION-HOUR QUESTION

What and how we teach reflect personal views of our responsibilities in libera! education, and thus clarity about objectives is crucial to significant debate about teaching strategies. Learning liberal arts disciplines is the basic purpose of a curricular view of liberal education. With this view, our most significant teaching decisions concern the content of our discipline, and debate about teaching methods is relatively unimportant. Another and more comprehensive view considers not only disciplinary content but also development of cognitive styles and socio-psychological attributes that help the student continue to learn and contribute in a complex world. Teaching methods are matters of great importance with this view.     

The dynamical evolution of Saturn's E-ring

The dynamical evolution of fine dust particles ejected from Enceladus and subsequently electrically charged within the Saturnian magnetosphere is studied. It is shown that the gyro-phase drift, which is radially outwards due to the strong radial temperature and density gradients in the magnetospheric plasma, is, by far, the fastest transport mechanism of these grains. Maintenance of the E-ring in a steady state throughout the age of the solar system would need a mass loss from Enceladus of about 2 parts in 1000.     

Numerical simulation of fracture flow with a mixed-hybrid FEM stochastic discrete fracture network model

We introduce a discrete fracture network model of stationary Darcy flow in fractured rocks. We approximate the fractures by a network of planar circle disks, which is generated on the basis of statistical data obtained from field measurements. We then discretize this network into a mesh consisting of triangular elements placed in three-dimensional space. We use geometrical approximations in fracture planes, which allow for a significant simplification of the final triangular meshes. We consider two-dimensional Darcy flow in each fracture. In order to accurately simulate the channeling effect, we assign to each triangle an aperture defining its hydraulic permeability. For the discretization we use the lowest order Raviart-Thomas mixed finite element method. This method gives quite an accurate velocity field, which is computed directly and which satisfies the mass balance on each triangular element. We demonstrate the use of this method on a model problem with a known analytical solution and describe the generation and triangulation of the fracture network and the computation of fracture flow for a particular real situation.