Physical Sciences and Mathematics Commons^™

A Strategy For Estimating Tree Canopy Density Using Landsat 7 Etm+ And High Resolution Images Over Large Areas, C. Huang, Limin Yang, Bruce K. Wylie, Collin Homer

Publications of the US Geological Survey

INTRODUCTION

The Multi-Resolution Land Characteristics (MRLC) consortium was initiated in early 1990s to address the need for consistently developed national and regional land cover data (Loveland and Shaw, 1996). Through this consortium, a 1992-vintage National Land Cover Dataset (NLCD) was developed for the conterminous United States (Vogelmann et al., 2001), and a second generation National Land Cover Dataset (NLCD 2000) will be developed using 2000-vintage Landsat 7 Enhanced Thematic Mapper Plus (ETM+) images and ancillary data. The 2000 NLCD will consist of a suite of data layers relevant to many applications, including a tree canopy density layer describing percentage of …

Comparison Of Instream Methods For Measuring Hydrolic Conductivity In Sandy Streambeds, Matthew K. Landon, David L. Rus, F. Edwin Harvey

United States Geological Survey: Staff Publications

Streambed hydraulic conductivity (K) values were determined at seven stream transects in the Platte River Basin in Nebraska using different instream measurement techniques.

Longshore Sediment Transport As A Function Of Energy Dissipation, Ernest R. Smith, Ping Wang

Geology Faculty Publications

Experiments to measure waves, currents, and sediment transport rate for two breaker types, plunging and spilling, were conducted in a large-scale three-dimensional physical model. It was found that there was a large difference in cross-shore distribution and total sediment transport rate between the two breaker types. Total transport rates compared to existing predictive equations. The equations generally did not predict the data well. With the exception of the Kamphuis (1991) equation, which included a dependence on wave period, the predictive equations did not differentiate between breaker types.

Asymptotic Analysis Of Buffered Calcium Diffusion Near A Point Source, Arthur Sherman, Gregory D. Smith, Longxiang Dai, Robert M. Miura

Arts & Sciences Articles

The "domain" calcium (Ca2+) concentration near an open Ca2+ channel can be mod- eled as buffered diffusion from a point source. The concentration profiles can be well approximated by hemispherically symmetric steady-state solutions to a system of reaction-diffusion equations. After nondimensionalizing these equations and scaling space so that both reaction terms and the source amplitude are 0(1), we identify two dimensionless parameters, Cc and Eb, that correspond to the diffusion coefficients of dimensionless Ca2+ and buffer, respectively. Using perturbation methods, we derive approximations for the Ca2+ and buffer profiles in three asymptotic limits: (1) an "excess buffer approximation" (EBA), where …

Before And After Riparian Management: Sediment And Nutrient Exports From A Small Agricultural Catchment, Western Australia, Lucy Mckergow, David Weaver, I Prosser, R Grayson, A. E.G. Reed

Conference papers and presentations

Riparian vegetation can trap sediment and nutrients coming from hillslopes and reduce stream bank erosion. This study presents results from a 10 year stream monitoring program in a small agricultural catchment near Albany, Western Australia. In 1996, a 1.6 km stream reach was fenced, planted with eucalyptus species and managed separately from the adjacent paddocks. Stream flow, nutrient and sediment concentration data were collected at the downstream end of the fenced riparian area between 1991 and 2000, so there are data for the “before” and “after” riparian management periods. Suspended sediment concentrations fell dramatically following riparian management; the average event …

Relationships Between Stream Order And Management Priority: A Water Quality Case Study, David Weaver, Adrian Reed, John Grant

Conference papers and presentations

Seagrass, which once dominated the habitat of Oyster Harbour on the south coast of Western Australia has been replaced by macroalgae because of increased nutrient and sediment discharge from the rural dominated catchment. Total Phosphorus (TP), Total Nitrogen (TN), Suspended Sediment (SS) and Electrical Conductivity (EC) concentrations from a catchment – wide (168 sites), event-driven snapshot, water quality monitoring program conducted from 1994 to 1996, were analysed in relation to stream order and published survey data on riparian zone condition. This analysis was performed to examine relationships between stream order, riparian zone condition and water quality, and implications for the …

Effective Field Theory For The Small-X Evolution, I. Balitsky

Physics Faculty Publications

The small-x behavior of structure functions in the saturation region is determined by the non-linear generalization of the BFKL equation. I suggest the effective field theory for the small-x evolution which solves formally this equation. The result is the 2+1 functional integral for the structure functions at small x.

Coherent-Path Model For Nuclear Resonant Scattering Of Gamma Radiation From Nuclei Excited By Synchrotron Radiation, Gilbert R. Hoy, Jos Odeurs, Romain Coussement

Physics Faculty Publications

Previous theoretical descriptions of nuclear resonant scattering of synchrotron radiation have been based on the semiclassical optical model or on several quantum mechanical models. These models are fine but do not give a clear physical picture of all the processes. The theory presented here gives a clear physical picture of all the relevant aspects of nuclear resonant scattering. The model treats the nuclear resonant sample as a one-dimensional chain of "effective" nuclei. However, the model is deceptive. It only appears to be one dimensional. It actually treats the sample as a series of "effective" planes. The analysis uses the time-dependent …

Gamma Echo Interpreted As A Phase-Shift Induced Transparency, Gilbert R. Hoy, Jos Odeurs

Physics Faculty Publications

In the gamma-echo technique a radioactive source is moved, with respect to a nuclear-resonant absorber, during the lifetime of first-excited nuclear state. This introduces a phase shift between the source radiation and the radiation from the absorber. If the source is moved abruptly, introducing a pi phase shift, the time-dependent intensity shows a sharp increase in the intensity at that time, the "gamma echo." Using the recently developed one-dimensional quantum-mechanical model, based on the technique developed by Heitler and Harris, the gamma-echo effect is seen to be a phase-shift-induced transparency. A closed-form solution for the time-dependent transmitted intensity has been …

Exclusive Electroproduction Of ᵠ Mesons At 4.2 Gev, M. Bektasoglu, L. Ciciani, G. E. Dodge, T. A. Forest, C. E. Hyde-Wright, S. E. Kuhn, L. M. Qin, F. Sabatié, L. B. Weinstein, Et Al., The Clas Collaboration

Physics Faculty Publications

We studied the exclusive reaction ep → e' p' ᵠ using the ᵠ →K⁺K^- decay mode. The data were collected using a 4.2 GeV incident electron beam and the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. Our experiment covers the range in Q² from 0.7 to 2.2 GeV²and W from 2.0 to 2.6 GeV. Taken together with all previous data, we find a consistent picture of ᵠ production on the proton. Our measurement shows the expected decrease of the t slope with the vector-meson formation time c Δ t …