Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
- Discipline
-
- Physics (84)
- Condensed Matter Physics (35)
- Environmental Sciences (29)
- Chemistry (20)
- Mathematics (19)
-
- Oceanography and Atmospheric Sciences and Meteorology (19)
- Earth Sciences (18)
- Life Sciences (15)
- Atmospheric Sciences (13)
- Computer Sciences (12)
- Geology (10)
- Elementary Particles and Fields and String Theory (9)
- Geometry and Topology (8)
- Statistics and Probability (7)
- Climate (6)
- Applied Mathematics (5)
- Natural Resources and Conservation (5)
- Water Resource Management (5)
- Algebra (4)
- Astrophysics and Astronomy (4)
- Biochemistry (4)
- Biochemistry, Biophysics, and Structural Biology (4)
- Biology (4)
- Cosmology, Relativity, and Gravity (4)
- Ecology and Evolutionary Biology (4)
- Soil Science (4)
- Medicine and Health Sciences (3)
- Other Environmental Sciences (3)
- Plant Sciences (3)
- Keyword
-
- Biconformal (3)
- Climate change (3)
- Drought (3)
- Einstein Field Equations (3)
- Einstein-Maxwell equations (3)
-
- Einstein-fluid equations (3)
- Einstein-scalar field equations (3)
- Gauge theory (3)
- General Relativity (3)
- Light emission (3)
- Materials testing (3)
- NBO (3)
- Rainich Conditions (3)
- Space environment effects (3)
- B3LYP (2)
- Bear Lake (2)
- Biomass (2)
- Canis lupus (2)
- Cathodoluminescence (2)
- Climate Change (2)
- Co-torsion (2)
- Coincident Rayleigh-Scatter (2)
- Conformal (2)
- Controlled study (2)
- Digital soil mapping (2)
- Dispersal (2)
- Electron scattering (2)
- Electrostatic discharge (2)
- Energy loss (2)
- Gravitational gauge theory: Weyl gravity (2)
- Publication
-
- All Graduate Theses and Dissertations, Spring 1920 to Summer 2023 (34)
- All Physics Faculty Publications (16)
- Presentations (16)
- Chemistry and Biochemistry Faculty Publications (15)
- Physics Capstone Projects (13)
-
- Wildland Resources Faculty Publications (12)
- Journal Articles (8)
- Plants, Soils, and Climate Faculty Publications (8)
- Posters (7)
- Geosciences Faculty Publications (6)
- Watershed Sciences Faculty Publications (6)
- Senior Theses and Projects (5)
- Conference publications (4)
- James Thomas Wheeler (4)
- Publications (4)
- Research Vignettes (4)
- All Graduate Plan B and other Reports, Spring 1920 to Spring 2023 (3)
- Browse All Undergraduate research (3)
- Environment and Society Faculty Publications (3)
- Tutorials on... in 1 hour or less (3)
- Graduate Student Posters (2)
- Presentations and Publications (2)
- Research on Capitol Hill (2)
- Wasatch Dendroclimatology Research (2)
- AggieAir Publications (1)
- All ECSTATIC Materials (1)
- All Physics Faculty Presentations (1)
- Biology Faculty Publications (1)
- Charles G. Torre (1)
- Christopher Monz (1)
- Publication Type
- File Type
Articles 1 - 30 of 196
Full-Text Articles in Physical Sciences and Mathematics
Long-Term Landscape Changes In A Subalpine Spruce-Fir Forest In Central Utah, Usa, Jesse L. Morris, R. Justin Derose, Andrea R. Brunelle
Long-Term Landscape Changes In A Subalpine Spruce-Fir Forest In Central Utah, Usa, Jesse L. Morris, R. Justin Derose, Andrea R. Brunelle
Wildland Resources Faculty Publications
Background: In Western North America, increasing wildfire and outbreaks of native bark beetles have been mediated by warming climate conditions. Bioclimatic models forecast the loss of key high elevation species throughout the region. This study uses retrospective vegetation and fire history data to reconstruct the drivers of past disturbance and environmental change. Understanding the relationship among climate, antecedent disturbances, and the legacy effects of settlement-era logging can help identify the patterns and processes that create landscapes susceptible to bark beetle epidemics. Methods: Our analysis uses data from lake sediment cores, stand inventories, and historical records. Sediment cores were dated with …
Selection For Forage And Avoidance Of Risk By Woodland Caribou (Rangifer Tarandus Caribou) At Coarse Andlocal Scales, Madeleine T. Mcgreer, Erin E. Mallon, Lucas M. Vander Vennen, Philip A. Wiebe, James A. Baker, Glen S. Brown, Tal Avgar, Jevon Hagens, Andrew M. Kittle, Anna Mosser, Garrett M. Street, Doug E. B. Reid, Arthur R. Rodgers, Jennifer Shuter, Ian D. Thompson, Et Al.
Selection For Forage And Avoidance Of Risk By Woodland Caribou (Rangifer Tarandus Caribou) At Coarse Andlocal Scales, Madeleine T. Mcgreer, Erin E. Mallon, Lucas M. Vander Vennen, Philip A. Wiebe, James A. Baker, Glen S. Brown, Tal Avgar, Jevon Hagens, Andrew M. Kittle, Anna Mosser, Garrett M. Street, Doug E. B. Reid, Arthur R. Rodgers, Jennifer Shuter, Ian D. Thompson, Et Al.
Wildland Resources Faculty Publications
The relationship between selection at coarse and fine spatiotemporal spatial scales is still poorly understood. Some authors claim that, to accommodate different needs at different scales, individuals should have contrasting selection patterns at different scales of selection, while others claim that coarse scale selection patterns should reflect fine scale selection decisions. Here we examine site selection by 110 woodland caribou equipped with GPS radio‐collars with respect to forage availability and predation risk across a broad gradient in availability of both variables in boreal forests of Northern Ontario. We tested whether caribou selection for forage and avoidance of risk was consistent …
Comparison Of Coincident Rayleigh-Scatter And Sodium Resonance Lidar Temperature Measurements From The Mesosphere-Lower-Thermosphere Region, Leda Sox, Vincent B. Wickwar, Neal R. Criddle, Tao Yuan
Comparison Of Coincident Rayleigh-Scatter And Sodium Resonance Lidar Temperature Measurements From The Mesosphere-Lower-Thermosphere Region, Leda Sox, Vincent B. Wickwar, Neal R. Criddle, Tao Yuan
All Physics Faculty Publications
There are relatively few instruments that have the capabilities to make near continuous measurements of the mesosphere-lower-thermosphere (MLT) region. Rayleigh scatter and resonance lidars, particularly sodium resonance lidar, have been the two dominant ground-based techniques for acquiring mesosphere and MLT vertical temperature profiles, respectively, for more than two decades. With these measurements, the dynamics (gravity waves, tides) and long-term temperature trends (upper atmosphere cooling) of the MLT region can be studied. The Utah State University (USU; 41.7º N, 111.8º W) campus hosts a unique upper atmospheric observatory which houses both a high-power, large-aperture Rayleigh lidar and a sodium resonance Doppler …
Comparison Of Coincident Rayleigh-Scatter And Sodium Resonance Lidar Temperature Measurements From The Mesosphere-Lower-Thermosphere Region, Leda Sox, Vincent B. Wickwar, Neal R. Criddle, Tao Yuan
Comparison Of Coincident Rayleigh-Scatter And Sodium Resonance Lidar Temperature Measurements From The Mesosphere-Lower-Thermosphere Region, Leda Sox, Vincent B. Wickwar, Neal R. Criddle, Tao Yuan
All Physics Faculty Presentations
There are relatively few instruments that have the capabilities to make near continuous measurements of the mesosphere-lower-thermosphere (MLT) region. Rayleigh scatter and resonance lidars, particularly sodium resonance lidar, have been the two dominant ground-based techniques for acquiring mesosphere and MLT vertical temperature profiles, respectively, for more than two decades. With these measurements, the dynamics (gravity waves, tides) and long-term temperature trends (upper atmosphere cooling) of the MLT region can be studied. The Utah State University (USU; 41.7º N, 111.8º W) campus hosts a unique upper atmospheric observatory which houses both a high-power, large-aperture Rayleigh lidar and a sodium resonance Doppler …
Microsolvation Of Anions By Molecules Forming Ch∙∙X- Hydrogen Bonds, Steve Scheiner, Binod Nepal
Microsolvation Of Anions By Molecules Forming Ch∙∙X- Hydrogen Bonds, Steve Scheiner, Binod Nepal
Chemistry and Biochemistry Faculty Publications
Various anions were surrounded by n molecules of CF3H, which was used as a prototype CH donor solvent, and the structures and energies studied by M06-2X calculations with a 6-31+G∗∗ basis set. Anions considered included the halides F-, Cl-, Br- and I-, as well as those with multiple proton acceptor sites: CN-, NO3 -, HCOO-, CH3COO-, HSO4 -, H2PO4 -, and anions with higher charges SO4 2-, HPO4 2- and PO4 …
Genetic Analysis Of The Henry Mountains Bison Herd, Dustin H. Ranglack, Lauren K. Dobson, Johan T. Du Toit, James Derr
Genetic Analysis Of The Henry Mountains Bison Herd, Dustin H. Ranglack, Lauren K. Dobson, Johan T. Du Toit, James Derr
Wildland Resources Faculty Publications
Wild American plains bison (Bison bison) populations virtually disappeared in the late 1800s, with some remnant animals retained in what would become Yellowstone National Park and on private ranches. Some of these private bison were intentionally crossbred with cattle for commercial purposes. This forced hybridization resulted in both mitochondrial and nuclear introgression of cattle genes into some of the extant bison genome. As the private populations grew, excess animals, along with their history of cattle genetics, provided founders for newly established public bison populations. Of the US public bison herds, only those in Yellowstone and Wind Cave National Parks (YNP …
Integrated Step Selection Analysis: Bridgingthe Gap Between Resource Selection And Animal Movement, Tal Avgar, Jonathan R. Potts, Mark A. Lewis, Mark S. Boyce
Integrated Step Selection Analysis: Bridgingthe Gap Between Resource Selection And Animal Movement, Tal Avgar, Jonathan R. Potts, Mark A. Lewis, Mark S. Boyce
Wildland Resources Faculty Publications
A resource selection function is a model of the likelihood that an available spatial unit will be used by an animal, given its resource value. But how do we appropriately define availability? Step selection analysis deals with this problem at the scale of the observed positional data, by matching each ‘used step’ (connecting two consecutive observed positions of the animal) with a set of ‘available steps’ randomly sampled from a distribution of observed steps or their characteristics. Here we present a simple extension to this approach, termed integrated step selection analysis (iSSA), which relaxes the implicit assumption that observed movement …
On The Construction Of Simply Connected Solvable Lie Groups, Mark E. Fels
On The Construction Of Simply Connected Solvable Lie Groups, Mark E. Fels
Research Vignettes
This worksheet contains the implementation of Theorems 4.2, 5.4 and 5.7 in the paper On the Construction of Solvable Lie Groups. All the examples in the paper are demonstrated here, along with one in Section 6 that was too long to include in the article.
Substituent Effects On The Binding Of Halides By Neutral And Dicationic Bis-Triazolium Receptors, Binod Nepal, Steve Scheiner
Substituent Effects On The Binding Of Halides By Neutral And Dicationic Bis-Triazolium Receptors, Binod Nepal, Steve Scheiner
Chemistry and Biochemistry Faculty Publications
The effects of substituent and overall charge upon the binding of a halide anion by a bis-triazolium receptor are studied by M06-2X DFT calculations, with the aug-cc-pVDZ basis set. Comparison is also made between a receptor that engages in H-bonds, with a halogen-bonding species. Fluoride is clearly most strongly bound, followed by Cl-, Br-, and I- in that order. The dicationic receptor engages in stronger complexes, but not by a very wide margin compared to its neutral counterpart. The binding is enhanced as the substituent on the two triazolium rings becomes progressively more electron-withdrawing. Halogen-substituted receptors, whether neutral or cationic, …
The First Bromeligenous Species Of Dendropsophus (Anura: Hylidae) From Brazil's Atlantic Forest, Rodrigo Barbosa Ferreira, Julián Faivovich, Karen H. Beard, José P. Pombal Jr
The First Bromeligenous Species Of Dendropsophus (Anura: Hylidae) From Brazil's Atlantic Forest, Rodrigo Barbosa Ferreira, Julián Faivovich, Karen H. Beard, José P. Pombal Jr
Wildland Resources Faculty Publications
We describe a new treefrog species of Dendropsophus collected on rocky outcrops in the Brazilian Atlantic Forest. Ecologically, the new species can be distinguished from all known congeners by having a larval phase associated with rainwater accumulated in bromeliad phytotelms instead of temporary or lentic water bodies. Phylogenetic analysis based on molecular data confirms that the new species is a member of Dendropsophus; our analysis does not assign it to any recognized species group in the genus. Morphologically, based on comparison with the 96 known congeners, the new species is diagnosed by its small size, framed dorsal color pattern, and …
Mantle-Derived Helium In Hot Springs Of The Cordillera Blanca, Peru: Implications For Mantle-To-Crust Fluid Transfer In A Flat-Slab Subduction Setting, Dennis L. Newell, Micah J. Jessup, David R. Hilton, Colin Shaw, Cameron Hughes
Mantle-Derived Helium In Hot Springs Of The Cordillera Blanca, Peru: Implications For Mantle-To-Crust Fluid Transfer In A Flat-Slab Subduction Setting, Dennis L. Newell, Micah J. Jessup, David R. Hilton, Colin Shaw, Cameron Hughes
Geosciences Faculty Publications
Fault-controlled hot springs in the Cordillera Blanca, Peru provide geochemical evidence of mantle-derived fluids in a modern flat-slab subduction setting. The Cordillera Blanca is an ~200km-long mountain range that contains the highest peaks in the Peruvian Andes, located in an amagmatic reach of the Andean arc. The Cordillera Blanca detachment defines the southwestern edge of the range and records a progression of top-down-to-the-west ductile shear to brittle normal faulting since ~5Ma. Hot springs, recording temperatures up to 78°C, issue along this fault zone and are CO2-rich, near neutral, alkaline-chloride to alkaline-carbonate waters, with elevated trace metal contents including …
The Schwarzschild Solution And Timelike Geodesics, Matthew B. Ross
The Schwarzschild Solution And Timelike Geodesics, Matthew B. Ross
Physics Capstone Projects
General Relativity is a major area of study in physics. It allows us to calculate the motion and interaction of particles in a non-Euclidean space-time. This presentation will examine the process of finding the Schwarzschild metric tensor field by finding a solution of the Einstein Equation for a non-rotating spherical mass. A general form of the Schwarzschild metric tenor field will be used to calculate the Riemann curvature tensor and subsequently the Ricci tensor and Ricci scalar which will be used to find a vacuum solution to the Einstein Equation. Once the solutions of the Einstein Equation are found, they …
Estimation Of Cold Plasma Outflow During Geomagnetic Storms, S. Haaland, A. Eriksson, M. Andre, L. Maes, L. Baddeley, A. Barakat, R. Chappell, V. Eccles, C. Johnsen, B. Lybekk, K. Li, A. Pedersen, Robert W. Schunk, D. Welling
Estimation Of Cold Plasma Outflow During Geomagnetic Storms, S. Haaland, A. Eriksson, M. Andre, L. Maes, L. Baddeley, A. Barakat, R. Chappell, V. Eccles, C. Johnsen, B. Lybekk, K. Li, A. Pedersen, Robert W. Schunk, D. Welling
All Physics Faculty Publications
Low-energy ions of ionospheric origin constitute a significant contributor to the magnetospheric plasma population. Measuring cold ions is difficult though. Observations have to be done at sufficiently high altitudes and typically in regions of space where spacecraft attain a positive charge due to solar illumination. Cold ions are therefore shielded from the satellite particle detectors. Furthermore, spacecraft can only cover key regions of ion outflow during segments of their orbit, so additional complications arise if continuous longtime observations, such as during a geomagnetic storm, are needed. In this paper we suggest a new approach, based on a combination of synoptic …
Predictive Formula For Electron Range Over A Large Span Of Energy, Anne C. Starley, Jr Dennison
Predictive Formula For Electron Range Over A Large Span Of Energy, Anne C. Starley, Jr Dennison
Senior Theses and Projects
A model developed by the Materials Research Group that calculates electron penetration range of some common materials, has been greatly expanded with the hope that such extensions will predict the range in other, perhaps, more interesting materials. Developments in this extended model aid in predicting the approximate penetration depth into diverse classes of materials for a broad range of energetic incident electrons (<10 eV to>10 MeV, with better than 20% accuracy). The penetration depth—or range—of a material describes the maximum distance electrons can travel through a material, before losing all of its incident kinetic energy. This model has started to predict …10>
Spatiotemporal Patterns Of Ring-Width Variability In The Northern Interior West, R. Justin Derose, John D. Shaw, James N. Long
Spatiotemporal Patterns Of Ring-Width Variability In The Northern Interior West, R. Justin Derose, John D. Shaw, James N. Long
Wasatch Dendroclimatology Research
A fundamental goal of forest biogeography is to understand the factors that drive spatiotemporal variability in forest growth across large areas (e.g., states or regions). The ancillary collection of increment cores as part of the IW FIA Program represents an important non-traditional role for the development of unprecedented data sets. Individual-tree growth data from increment cores were paired with plot-level variables from the inventory to investigate the spatiotemporal growth patterns for Douglas-fir, ponderosa pine, common pinyon, and limber pine over the northern portion of the Interior West (Idaho, Montana, Wyoming, Utah, and Colorado). Based on dendrochronological theory proposed over 50 …
Predictive Formula For Electron Range Over A Large Span Of Energy, Anne C. Starley
Predictive Formula For Electron Range Over A Large Span Of Energy, Anne C. Starley
Reports
A model developed by the Materials Research Group that calculates electron penetration range of some common materials, has been greatly expanded with the hope that such extensions will predict the range in other, perhaps, more interesting materials. Developments in this extended model aid in predicting the approximate penetration depth into diverse classes of materials for a broad range of energetic incident electrons (10 MeV, with better than 20% accuracy). The penetration depth—or range—of a material describes the maximum distance electrons can travel through a material, before losing all of its incident kinetic energy. This model has started to predict a …
Differentialgeometry In Brno, Ian M. Anderson
Differentialgeometry In Brno, Ian M. Anderson
Presentations
This page will provide files supporting Ian Anderson's presentations in Brno, December 2015. The files can be found and downloaded from "Additional Files", below.
The files include:
(1) DifferentialGeometryUSU.mla: This is the Maple Library Archive file which provides all the DifferentialGeometry functionality. Here are Installation Instructions.
(2) DifferentialGeometry.help : this is the latest version of the DifferentialGeometry documentation. Copy this file to the same directory used for DifferentialGeometryUSU.mla (from step (1)).
Modelling Water Uptake Provides A New Perspective On Grass And Tree Coexistence, Michael G. Mazzacavallo, Andrew Kulmatiski
Modelling Water Uptake Provides A New Perspective On Grass And Tree Coexistence, Michael G. Mazzacavallo, Andrew Kulmatiski
Wildland Resources Faculty Publications
Root biomass distributions have long been used to infer patterns of resource uptake. These patterns are used to understand plant growth, plant coexistence and water budgets. Root biomass, however, may be a poor indicator of resource uptake because large roots typically do not absorb water, fine roots do not absorb water from dry soils and roots of different species can be difficult to differentiate. In a sub-tropical savanna, Kruger Park, South Africa, we used a hydrologic tracer experiment to describe the abundance of active grass and tree roots across the soil profile. We then used this tracer data to parameterize …
Improving The Resilience Of Mixed-Farm Systems To Pending Climate Change In Far Western Nepal: Endline Survey Report, D. Layne Coppock
Improving The Resilience Of Mixed-Farm Systems To Pending Climate Change In Far Western Nepal: Endline Survey Report, D. Layne Coppock
Environment and Society Faculty Publications
This report presents general findings from an endline survey carried out during May 2015 in Jugada, Budhiganga, Attichaur and Gudukhati Village Development Committees (VDCs) in Bajura District. A total of 320 households were surveyed, a total of 80 per VDC. Two of the VDCs—Jugada and Budhiganga—received capacity-building interventions for 16 months concerning climate-change adaptation, poverty reduction, and other aspects of well-being, while two VDCs—Attichaur and Gudkhati—were their "paired controls," respectively, that did not receive interventions. The interventions were largely delivered as informal educational or training modules.
Backlund Transformation For 3 Rt + 1 = 0 (Example 3.4), Ian M. Anderson, Mark E. Fels
Backlund Transformation For 3 Rt + 1 = 0 (Example 3.4), Ian M. Anderson, Mark E. Fels
Research Vignettes
In this worksheet we give all the calculations for Example 3.4 in "Backlund Transformations for Darboux Integrable Differential Systems: Examples and Applications"
A Backlund Transformation For The A2 Toda System (Example 3.4), Ian M. Anderson, Mark E. Fels
A Backlund Transformation For The A2 Toda System (Example 3.4), Ian M. Anderson, Mark E. Fels
Research Vignettes
This worksheet amplifies results associated to example 3.4 in "Backlund Transformations for Darboux Integrable Differential Systems: Examples and Applications".
Classical Examples Of Bäcklund Transformations (Examples 3.1, 3.2, 5.1), Ian M. Anderson, Mark E. Fels
Classical Examples Of Bäcklund Transformations (Examples 3.1, 3.2, 5.1), Ian M. Anderson, Mark E. Fels
Research Vignettes
This worksheet contains the detailed calculations for Example 3.1, Example 3.2, and Example 5.1 in the paper Bäcklund Transformations for Darboux Integrable Differential Systems: Examples and Applications.
The Role Of Space Materials Research In Spacecraft Charging And Satellite Survivability, Jr Dennison
The Role Of Space Materials Research In Spacecraft Charging And Satellite Survivability, Jr Dennison
Presentations
No abstract provided.
An Overview Of The Dynamic Interplay Between The Space Environment & Spacecraft Materials, Jr Dennison
An Overview Of The Dynamic Interplay Between The Space Environment & Spacecraft Materials, Jr Dennison
Presentations
No abstract provided.
Daytime Plasma Drifts In The Equatorial Lower Ionosphere, D. Hui, B. G. Fejer
Daytime Plasma Drifts In The Equatorial Lower Ionosphere, D. Hui, B. G. Fejer
All Physics Faculty Publications
We have used extensive radar measurements from the Jicamarca Observatory during low solar flux periods to study the quiet time variability and altitudinal dependence of equatorial daytime vertical and zonal plasma drifts. The daytime vertical drifts are upward and have largest values during September-October. The day-to-day variability of these drifts does not change with height between 150 and 600 km, but the bimonthly variability is much larger in the F region than below about 200 km. These drifts vary linearly with height generally increasing in the morning and decreasing in the afternoon. The zonal drifts are westward during the day …
Electrically Induced Plasma, Nate Ashby
Electrically Induced Plasma, Nate Ashby
Physics Capstone Projects
My research project, under the mentorship of research professor Ajay Singh was to prove that the plasma he was creating was lasting longer than the electrical current data indicated. He decided that if the plasma was still there, it would be producing light. So we set out to prove that the light emitted from his plasma lasted longer than the current draw measurements.
Dependence Of Electrostatic Field Strength On Voltage Ramp Rates For Spacecraft Materials, Krysta Moser
Dependence Of Electrostatic Field Strength On Voltage Ramp Rates For Spacecraft Materials, Krysta Moser
Senior Theses and Projects
No abstract provided.
Installation Instructions, Ian M. Anderson, Charles G. Torre
Installation Instructions, Ian M. Anderson, Charles G. Torre
Downloads
DifferentialGeometry and DGApplications are contained in Maple library archives (mla files). The documentation is contained in Maple help files. Unzip the downloaded file (if necessary) to reveal the mla and help files.
To install a package, proceed as follows.
(1) Create or identify a directory (folder) where you will keep the mla file(s) and the help file. This should be a directory of your own, not belonging to Maple (e.g., do not use the Maple "lib" directory). Copy the mla and help files there.
(2) Open Maple, at the prompt type libname. This will display where maple currently looks for …
Pre-Breakdown Arcing As A Proxy For Dc Dielectric Breakdown Testing Of Polymeric Insulators, Jr Dennison, Allen Andersen
Pre-Breakdown Arcing As A Proxy For Dc Dielectric Breakdown Testing Of Polymeric Insulators, Jr Dennison, Allen Andersen
Presentations
No abstract provided.
Mixed Weibull Distribution Model Of Dc Dielectric Breakdowns With Dual Defect Modes, Allen Andersen, Jr Dennison
Mixed Weibull Distribution Model Of Dc Dielectric Breakdowns With Dual Defect Modes, Allen Andersen, Jr Dennison
Journal Articles
This work provides physical insight into common statistical models for DC dielectric breakdown field strengths. Voltage step-up tests were performed on low density polyethylene films. The merits of generalizations to widely-used empirical Weibull models are discussed. The cumulative probability distributions of the breakdown fields were fit to standard two- and three-parameter Weibull distributions. Mixed two-parameter Weibull distributions, sometimes used in the literature to model multiple breakdown modes, were found to yield the best fits to the data. In addition, the same data were fit to a physically-motivated dual-defect mean field model incorporating both low- and high-energy defect modes with different …