Rhett Herman | Radford University (original) (raw)

Papers by Rhett Herman

AGUSM, May 1, 2008

A shallow capacitively coupled resistivity survey was performed in Saltville, VA, in an area of s... more A shallow capacitively coupled resistivity survey was performed in Saltville, VA, in an area of suspected buried Pleistocene river deposits. Previous excavations in the sediments beneath the Saltville valley floor had been performed to recover late Pleistocene megafaunal remains and possible Clovis-age human artifacts. These digs encountered a zone, one to two meters deep, of gravel-sized rock fragments, including some boulders up to 75 cm. in diameter. These large clasts are rounded, show some imbrication (shingle-like overlapping indicative of current flow), and have been interpreted as river channel deposits. Carbon 14 dates from the megafaunal bones within and just above the gravel bed yielded dates of 14,500 years BP. Resistivity signals in a number of locations were consistent with cobbles and boulders deposited in a river channel. These signals are generally bowl- shaped areas with large circular (2-d scans) anomalies near the center, and smaller circular anomalies tapering out towards both sides. The bowl-shaped anomalies are within 3 meters of the surface. With several lines imaged in this survey a rough path of the riverbed, along with a number of branchings is traceable in the survey area. An exploratory hole confirmed the presence of a layer of rounded cobbles and boulders 1.3 meters deep beneath one of the survey lines.

Proceedings of 2007 Joint Assembly of the AGU, 2007

A capacitively coupled resistivity survey was conducted on an archaeological site near Barrow, Al... more A capacitively coupled resistivity survey was conducted on an archaeological site near Barrow, Alaska in June of 2006. The purpose of this survey was to determine the effectiveness of resistivity studies in determining locations of near-surface burials and other features of interest. This survey was performed on an area 14mx160m, with line spacings of 1 meter. Data was acquired at 6 depths with the nearest to the surface being obtained with an unusually-short n-spacing of (n/4). This allowed for visualization of subsurface features as small as ~20cm, and at depths as shallow as ~20cm. The greatest depths seen were ~2m below the surface. The data was processed in a preliminary fashion during the course of the survey and several near-surface features were seen that were consistent with burials. Upon inspection, the surface vegetation and small-scale topography were visually consistent with burials. An archaeological team dug pits in three of these areas and all three were determined t...

The DeWitt-Schwinger proper time point-splitting procedure is applied to a massive complex scalar... more The DeWitt-Schwinger proper time point-splitting procedure is applied to a massive complex scalar field with arbitrary curvature coupling interacting with a classical electromagnetic field in a general curved spacetime. The scalar field current is found to have a linear divergence. The presence of the external background gauge field is found to modify the stress-energy tensor results of Christensen for the neutral scalar field by adding terms of the form (eF)^2 to the logarithmic counterterms. These results are shown to be expected from an analysis of the degree of divergence of scalar quantum electrodynamics.

The Physics Teacher, 2014

Many of us have grabbed two pieces of aluminum foil and a paper towel, quickly sandwiched them to... more Many of us have grabbed two pieces of aluminum foil and a paper towel, quickly sandwiched them together, and exclaimed in lecture, “Look! It's easy to make a capacitor!” Then we move on from there, calculating things such as capacitances with various dielectrics or plate sizes, the capacitance of capacitor networks, RC circuits, etc. We typically do these calculations with capacitance values that are far removed from what we just created in our quick demonstration of a capacitor. Students might justifiably question whether the capacitor that we blithely made has any relation to the values that we are using in our calculations. It may be useful to investigate the quality of such handmade capacitors so that our students get a more intuitive feel for these ubiquitous electrical components.

Whenever real particle production occurs in quantum field theory, the imaginary part of the Hadam... more Whenever real particle production occurs in quantum field theory, the imaginary part of the Hadamard Elementary function G^(1) is non-vanishing. A method is presented whereby the imaginary part of G^(1) may be calculated for a charged scalar field in a static spherically symmetric spacetime with arbitrary curvature coupling and a classical electromagnetic field A^μ. The calculations are performed in Euclidean space where the Hadamard Elementary function and the Euclidean Green function are related by (1/2)G^(1)=G_E. This method uses a 4^th order WKB approximation for the Euclideanized mode functions for the quantum field. The mode sums and integrals that appear in the vacuum expectation values may be evaluated analytically by taking the large mass limit of the quantum field. This results in an asymptotic expansion for G^(1) in inverse powers of the mass m of the quantum field. Renormalization is achieved by subtracting off the terms in the expansion proportional to nonnegative power...

The DeWitt-Schwinger proper time point-splitting procedure is applied to a massive complex scalar... more The DeWitt-Schwinger proper time point-splitting procedure is applied to a massive complex scalar field with arbitrary curvature coupling interacting with a classical electromagnetic field in a general curved spacetime. The scalar field current is found to have a linear divergence. The presence of the external background gauge field is found to modify the stress-energy tensor results of Christensen for the neutral scalar field by adding terms of the form (eF) 2 to the logarithmic counterterms. These results are shown to be expected from an analysis of the degree of divergence of scalar quantum electrodynamics. Typeset using REVTEX 1 I.

The Nuvuk site is currently eroding at an average rate measured at over 6 m/year. Prior archaeolo... more The Nuvuk site is currently eroding at an average rate measured at over 6 m/year. Prior archaeological work at the site had recovered over 80 burials with nearly 100 individuals represented, all of which were less than 1 m below surface, and detectable with small test pits. In addition, the first coastal Ipiutak occupation known north of Point Hope had been recently discovered, at a depth of nearly 2m below surface, in the erosion face. The occupation appeared to have been terminated by a large storm which overwashed the site, leaving a strandline immediately superimposed on the living surface. After that, approximately 1.5 m of sterile gravels had been deposited before the surface on which the Thule people were living formed. Both occupations are of considerable scientific interest.

A capacitively coupled resistivity survey was conducted on the sea ice near Barrow, Alaska in Mar... more A capacitively coupled resistivity survey was conducted on the sea ice near Barrow, Alaska in March 2008, as part of a continuing effort to understand the meter-scale structure of seasonal arctic sea ice. Data was collected on the Chukchi Sea, on ice approximately 3 months old and ~ 200m offshore from the Naval Arctic Research Laboratory. Data was collected along

Proceedings of the Seventh Marcel Grossman Meeting on Recent Developments in Theoretical and Experimental General Relativity Gravitation and Relativistic Field Theories, 1996

American Journal of Physics, 2009

AGUSM, May 1, 2008

A shallow capacitively coupled resistivity survey was performed in Saltville, VA, in an area of s... more A shallow capacitively coupled resistivity survey was performed in Saltville, VA, in an area of suspected buried Pleistocene river deposits. Previous excavations in the sediments beneath the Saltville valley floor had been performed to recover late Pleistocene megafaunal remains and possible Clovis-age human artifacts. These digs encountered a zone, one to two meters deep, of gravel-sized rock fragments, including some boulders up to 75 cm. in diameter. These large clasts are rounded, show some imbrication (shingle-like overlapping indicative of current flow), and have been interpreted as river channel deposits. Carbon 14 dates from the megafaunal bones within and just above the gravel bed yielded dates of 14,500 years BP. Resistivity signals in a number of locations were consistent with cobbles and boulders deposited in a river channel. These signals are generally bowl- shaped areas with large circular (2-d scans) anomalies near the center, and smaller circular anomalies tapering out towards both sides. The bowl-shaped anomalies are within 3 meters of the surface. With several lines imaged in this survey a rough path of the riverbed, along with a number of branchings is traceable in the survey area. An exploratory hole confirmed the presence of a layer of rounded cobbles and boulders 1.3 meters deep beneath one of the survey lines.

Proceedings of 2007 Joint Assembly of the AGU, 2007

A capacitively coupled resistivity survey was conducted on an archaeological site near Barrow, Al... more A capacitively coupled resistivity survey was conducted on an archaeological site near Barrow, Alaska in June of 2006. The purpose of this survey was to determine the effectiveness of resistivity studies in determining locations of near-surface burials and other features of interest. This survey was performed on an area 14mx160m, with line spacings of 1 meter. Data was acquired at 6 depths with the nearest to the surface being obtained with an unusually-short n-spacing of (n/4). This allowed for visualization of subsurface features as small as ~20cm, and at depths as shallow as ~20cm. The greatest depths seen were ~2m below the surface. The data was processed in a preliminary fashion during the course of the survey and several near-surface features were seen that were consistent with burials. Upon inspection, the surface vegetation and small-scale topography were visually consistent with burials. An archaeological team dug pits in three of these areas and all three were determined t...

The DeWitt-Schwinger proper time point-splitting procedure is applied to a massive complex scalar... more The DeWitt-Schwinger proper time point-splitting procedure is applied to a massive complex scalar field with arbitrary curvature coupling interacting with a classical electromagnetic field in a general curved spacetime. The scalar field current is found to have a linear divergence. The presence of the external background gauge field is found to modify the stress-energy tensor results of Christensen for the neutral scalar field by adding terms of the form (eF)^2 to the logarithmic counterterms. These results are shown to be expected from an analysis of the degree of divergence of scalar quantum electrodynamics.

The Physics Teacher, 2014

Many of us have grabbed two pieces of aluminum foil and a paper towel, quickly sandwiched them to... more Many of us have grabbed two pieces of aluminum foil and a paper towel, quickly sandwiched them together, and exclaimed in lecture, “Look! It's easy to make a capacitor!” Then we move on from there, calculating things such as capacitances with various dielectrics or plate sizes, the capacitance of capacitor networks, RC circuits, etc. We typically do these calculations with capacitance values that are far removed from what we just created in our quick demonstration of a capacitor. Students might justifiably question whether the capacitor that we blithely made has any relation to the values that we are using in our calculations. It may be useful to investigate the quality of such handmade capacitors so that our students get a more intuitive feel for these ubiquitous electrical components.

Whenever real particle production occurs in quantum field theory, the imaginary part of the Hadam... more Whenever real particle production occurs in quantum field theory, the imaginary part of the Hadamard Elementary function G^(1) is non-vanishing. A method is presented whereby the imaginary part of G^(1) may be calculated for a charged scalar field in a static spherically symmetric spacetime with arbitrary curvature coupling and a classical electromagnetic field A^μ. The calculations are performed in Euclidean space where the Hadamard Elementary function and the Euclidean Green function are related by (1/2)G^(1)=G_E. This method uses a 4^th order WKB approximation for the Euclideanized mode functions for the quantum field. The mode sums and integrals that appear in the vacuum expectation values may be evaluated analytically by taking the large mass limit of the quantum field. This results in an asymptotic expansion for G^(1) in inverse powers of the mass m of the quantum field. Renormalization is achieved by subtracting off the terms in the expansion proportional to nonnegative power...

The DeWitt-Schwinger proper time point-splitting procedure is applied to a massive complex scalar... more The DeWitt-Schwinger proper time point-splitting procedure is applied to a massive complex scalar field with arbitrary curvature coupling interacting with a classical electromagnetic field in a general curved spacetime. The scalar field current is found to have a linear divergence. The presence of the external background gauge field is found to modify the stress-energy tensor results of Christensen for the neutral scalar field by adding terms of the form (eF) 2 to the logarithmic counterterms. These results are shown to be expected from an analysis of the degree of divergence of scalar quantum electrodynamics. Typeset using REVTEX 1 I.

The Nuvuk site is currently eroding at an average rate measured at over 6 m/year. Prior archaeolo... more The Nuvuk site is currently eroding at an average rate measured at over 6 m/year. Prior archaeological work at the site had recovered over 80 burials with nearly 100 individuals represented, all of which were less than 1 m below surface, and detectable with small test pits. In addition, the first coastal Ipiutak occupation known north of Point Hope had been recently discovered, at a depth of nearly 2m below surface, in the erosion face. The occupation appeared to have been terminated by a large storm which overwashed the site, leaving a strandline immediately superimposed on the living surface. After that, approximately 1.5 m of sterile gravels had been deposited before the surface on which the Thule people were living formed. Both occupations are of considerable scientific interest.

A capacitively coupled resistivity survey was conducted on the sea ice near Barrow, Alaska in Mar... more A capacitively coupled resistivity survey was conducted on the sea ice near Barrow, Alaska in March 2008, as part of a continuing effort to understand the meter-scale structure of seasonal arctic sea ice. Data was collected on the Chukchi Sea, on ice approximately 3 months old and ~ 200m offshore from the Naval Arctic Research Laboratory. Data was collected along

Proceedings of the Seventh Marcel Grossman Meeting on Recent Developments in Theoretical and Experimental General Relativity Gravitation and Relativistic Field Theories, 1996

American Journal of Physics, 2009