Host Galaxy Extinction Of Type Ia Supernovae : Co-Evolution Of Interstellar Medium Structure And The Extinction Law With Star Formation., Benne W. Holwerda
This paper presents a mechanism that may modify the extinction law for Type Ia supernovae (SNeIa) observed at higher redshift. Starting from the observations that (i) SNeIa occur predominantly in spiral galaxies, (ii) star formation ejects interstellar medium (ISM) out of the plane of spirals, (iii) star formation alters the extinction properties of the dust in the ISM, and (iv) there is substantially more star formation at higher redshift, I propose that spiral galaxies have a dustier halo in the past than they do now. The ejected material’s lower value of RV will lead to a lower average value ...
A Dust Component ~2 Kpc Above The Plane In Ngc 891., 2017 University of Groningen
A Dust Component ~2 Kpc Above The Plane In Ngc 891., P. Kamphuis, Benne W. Holwerda, R. J. Allen, R. F. Peletier, P. C. Van Der Kruit
Context.The halo of NGC 891 has been the subject of studies for more than a decade. One of its most striking features is the large asymmetry in H emission. In this letter, we will take a quantitative look at this asymmetry at different wavelengths for the first time.
Aims.We suggest that NGC 891 is intrinsically almost symmetric and the large asymmetry in H emission is mostly due to dust attenuation. We will quantify the additional optical depth needed to cause the observed asymmetry in this model.
Methods.By comparing large strips on the North East side of the ...
Relaxation Of Radiation Effects On The Optical Transmission Of Polymers, 2017 Utah State University
Relaxation Of Radiation Effects On The Optical Transmission Of Polymers, Alexandra Hughlett, Tyler Kippen, J. R. Dennison
Changes in optical transmission of polymers over time were studied to determine the factors contributing to relaxation of defect states induced by intense radiation doses. Samples of low density polyethylene (LDPE), polyether ether ketone (PEEK), polypropylene (PP), and polyimide (PI) received doses up to 500 MGy from an 8 MeV electron accelerator. These doses were intended to simulate long-term exposure of common spacecraft materials in geosynchronous orbit. Features and absorption edges in ~250 nm to 1000 nm UV to IR transmission spectra can be related to energies associated with various defects previously observed in these highly disordered materials. Recent work ...
Pulsed Electroacoustic System Development For Volume Charge Distribution Measurement In Thin Dielectric Films, 2017 Box Elder Innovations
Pulsed Electroacoustic System Development For Volume Charge Distribution Measurement In Thin Dielectric Films, Lee H. Pearson, Jr Dennison, Erick W. Griffiths, Anthony C. Pearson
This paper discusses an effort to develop advanced pulsed electroacoustic (PEA) measurement system capabilities that incorporate state-of-the-art hardware and improved signal processing and modeling to characterize embedded charge distributions in thin dielectric films. Objectives in developing this system include: (1) improved spatial resolution, while maintaining reasonable temporal resolution; (2) improved signal processing tools for increased signal/noise ratios; (3) integrated PEA modeling tools; and (4) integrated environmental controls. We emphasize system improvements required to achieve high spatial resolution for in vacuo measurements of thin dielectrics charged using electron beam injection, which are most applicable for spacecraft charging tests. PEA measurement ...
Vacuum.Doc, 2017 Yanbikov Vildyan Shavkyatovich
Vacuum.Doc, Vildyan Yanbikov
A New Physical Model For Dc Partial Discharge In Polymeric Insulators, 2017 Utah State University
A New Physical Model For Dc Partial Discharge In Polymeric Insulators, Allen Andersen, Jr Dennison
The physics of DC partial discharge (DCPD) continues to pose a challenge to researchers. We present a new physically-motivated model of DCPD in amorphous polymers based on our dual-defect model of dielectric breakdown. The dual-defect model is an extension of standard static mean field theories, such as the Crine model, that describe avalanche breakdown of charge carriers trapped on uniformly distributed defect sites. It assumes the presence of both high-energy chemical defects and low-energy thermally-recoverable physical defects. We present our measurements of breakdown and DCPD for several common polymeric materials in the context of this model. Improved understanding of DCPD ...
Model For Charge Injection With Electron Beams Into Highly Disordered Insulating Materials, 2017 Utah State Univesity
Model For Charge Injection With Electron Beams Into Highly Disordered Insulating Materials, Jr Dennison
The Walden-Wintle model for charge injection and transport through highly disordered insulating materials has been extended to include charge injection with a charged particle beam. The original model is applicable to charge injection into a dielectric material from a pair of electrodes in a parallel-plate geometry. It provides a versatile approach to predict the time-dependent current at a rear grounded electrode and the incident surface voltage, as the injection current density evolves over time with the development of a space charge barrier near the injection electrode. The Walden-Wintle model has been applied to many standard cases including Fowler-Nordheim injection, Schottky ...
Willingness To Pay For Clear Lake Cleanup, 2017 Iowa State University
Willingness To Pay For Clear Lake Cleanup, Christopher D. Azevedo, Joseph A. Herriges Sr., Catherine L. Kling
The water quality in Iowa’s lakes has been a hot topic lately. Concerns about the water quality in many of the state’s lakes have brought increased attention to the value of the lakes as a recreational resource. One lake that has experienced recent water quality problems, as well as the accompanying publicity, is Clear Lake, located in Cerro Gordo County.
Valuing Water Quality In Midwestern Lake Ecosystems, 2017 Iowa State University
Valuing Water Quality In Midwestern Lake Ecosystems, Kevin J. Egan, Joseph A. Herriges Sr., Catherine L. Kling, John A. Downing
As increased attention is focused on the issue of water quality in the state of Iowa, policymakers must grapple with the pressures of balancing federal water quality requirements, tight conservation budgets, and citizen concern for environmental preservation and restoration of Iowa’s water resources. Efforts to improve water quality typically entail significant costs, either in the form of state resources to fund cleanup efforts or private costs associated with altering land uses, farming practices, municipal treatment facility expansions, or other investments.
Research Needs And Challenges In The Few System: Coupling Economic Models With Agronomic, Hydrologic, And Bioenergy Models For Sustainable Food, Energy, And Water Systems, Catherine L. Kling, Raymond W. Arritt, Gray Calhoun, David A. Keiser, John M. Antle, Jeffery G. Arnold, Miguel Carriquiry, Indrajeet Chaubey, Peter Christensen, Baskar Ganapathysubramanian, Philip Gassman, William Gutowski, Thomas W. Hertel, Gerritt Hoogenboom, Elena Irwin, Madhu Khanna, Pierre Mérel, Daniel J. Phaneuf, Andrew Plantinga, Stephen Polasky, Paul Preckel, Sergey Rabotyagov, Ivan Rudik, Silvia Secchi, Aaron Smith, Andrew Vanloocke, Calvin Wolter, Jinhua Zhao, Wendong Zhang
On October 12–13, a workshop funded by the National Science Foundation was held at Iowa State University in Ames, Iowa with a goal of identifying research needs related to coupled economic and biophysical models within the FEW system. Approximately 80 people attended the workshop with about half representing the social sciences (primarily economics) and the rest from the physical and natural sciences. The focus and attendees were chosen so that findings would be particularly relevant to SBE research needs while taking into account the critical connectivity needed between social sciences and other disciplines. We have identified several major gaps ...
The Optimality Of Using Marginal Land For Bioenergy Crops: Tradeoffs Between Food, Fuel, And Environmental Services, Adriana M. Valcu-Lisman, Catherine L. Kling, Philip W. Gassman
We assess empirically how agricultural lands should be used to produce the highest valued outputs, which include food, energy, and environmental goods and services. We explore efficiency tradeoffs associated with allocating land between food and bioenergy and use a set of market prices and nonmarket environmental values to value the outputs produced by those crops. We also examine the degree to which using marginal land for energy crops is an approximately optimal rule. Our empirical results for an agricultural watershed in Iowa show that planting energy crops on marginal land is not likely to yield the highest valued output.
Valuing Preservation And Improvements Of Water Quality In Clear Lake, 2017 Iowa State University
Valuing Preservation And Improvements Of Water Quality In Clear Lake, Christopher D. Azevedo, Joseph A. Herriges Sr., Catherine Kling
This report presents summary statistics and other results of a survey of Clear Lake visitors and residents. Drawing on survey results, the authors present information on recreational usage of the lake, attitudes of recreators and local residents toward possible watershed management changes, and estimates of visitors' and residents' willingness to pay for water quality improvements at the lake. Support for the survey was provided by the Iowa Department of Natural Resources.
Testing The Consistency Of Nested Logit Models With Utility Maximization, 2017 Iowa State University
Testing The Consistency Of Nested Logit Models With Utility Maximization, Joseph A. Herriges, Catherine L. Kling
The Nested Multinomial Logit (NMNL) model is used extensively in modeling consumer choices among discrete alternatives when the number of alternatives is large. Unfortunately, applied researchers often find that estimated NMNL models fail to meet the Daly-ZacharyMcFadden (DZM) sufficient conditions for consistency with stochastic utility maximization. Borsch-Supan (1990) provides a relaxed set of conditions to test for consistency. While these conditions are increasingly cited, they are seldom tested. This paper corrects and extends BorschSupan's Theorem 2, providing simple necessary conditions on first, second, and third derivatives of choice probabilities and a graph oft he bounds they place on dissimilarity ...
Least-Cost Control Of Agricultural Nutrient Contributions To The Gulf Of Mexico Hypoxic Zone, 2017 University of Washington
Least-Cost Control Of Agricultural Nutrient Contributions To The Gulf Of Mexico Hypoxic Zone, Sergey S. Rabotyagov, Todd Campbell, Manoj K. Jha, Hongli Feng, Philip W. Gassman, Lyubov A. Kurkalova, Sylvia Secchi, Catherine L. Kling
No abstract provided.
Impacts Of Climate Change On Hydrology, Water Quality And Crop Productivity In The Ohio-Tennessee River Basin, 2017 Iowa State University
Impacts Of Climate Change On Hydrology, Water Quality And Crop Productivity In The Ohio-Tennessee River Basin, Yiannis Panagopoulos, Philip W. Gassman, Raymond W. Arritt, Daryl E. Herzmann, Todd D. Campbell, Adriana Valcu, Manoj K. Jha, Catherine L. Kling, Raghavan Srinivasan, Michael White, Jeffrey G. Arnold
Nonpoint source pollution from agriculture is the main source of nitrogen and phosphorus in the stream systems of the Corn Belt region in the Midwestern US. The eastern part of this region is comprised of the Ohio-Tennessee River Basin (OTRB), which is considered a key contributing area for water pollution and the Northern Gulf of Mexico hypoxic zone. A point of crucial importance in this basin is therefore how intensive corn-based cropping systems for food and fuel production can be sustainable and coexist with a healthy water environment, not only under existing climate but also under climate change conditions in ...
Incentives To Boost Conservation Tillage Adoption, 2017 Iowa State University
Incentives To Boost Conservation Tillage Adoption, Lyubov A. Kurkalova, Catherine L. Kling
With increasing public demand for clear air and clean water, many inside and outside Washington, D.C., have suggested that federal farm income support should be tied to enhanced conservation practices.
Iowa’S Wetlands: Who Will Pay For Preservation?, 2017 Iowa State University
Iowa’S Wetlands: Who Will Pay For Preservation?, Joseph A. Herriges Sr., Catherine L. Kling
It is estimated that before the 1750s, Iowa had around 2.3 million acres of wetlands. Today, Iowa has about 35,000 acres, with over 98 percent of the original wetlands converted to other uses—primarily agricultural production.
Iowa Wetlands: Perceptions And Values, 2017 Iowa State University
Iowa Wetlands: Perceptions And Values, Christopher D. Azevedo, Joseph A. Herriges Sr., Catherine Kling
Understanding how Iowans view the benefits and costs of wetlands preservation is key to making decisions about the future of wetlands in Iowa. To that end, the authors created "The Iowa Wetlands Survey." How the survey was designed and administered is described and the results are summarized. The survey reveals important information about how Iowans use wetlands, what they know about wetlands, and how much they value preserving them.
A Tale Of Three Watersheds: Nonpoint Source Pollution And Conservation Practices Across Iowa, 2017 Iowa Geological Survey
A Tale Of Three Watersheds: Nonpoint Source Pollution And Conservation Practices Across Iowa, Keith E. Schilling, Mark D. Tomer, Philip W. Gassman, Catherine Kling, Thomas M. Isenhart, Thomas B. Moorman, William W. Simpkins, Calvin F. Wolter
Many conservation practices and implementation programs exist to address nonpoint source (NPS) pollution losses from agricultural landscapes (Helmers et al., this issue). In order to select the most appropriate practices and programs for reducing NPS pollution in a specific region while maintaining economic return for the landowner, the interacting processes of agricultural management and watershed hydrology need to be understood across broad spatial scales. On a nationwide basis, it is easy to see how NPS pollution in one part of the country might be different than those in another region of the country. For example, cotton growers in the South ...
Global Solutions To Regional Problems: Collecting Global Expertise To Address The Problem Of Harmful Cyanobacterial Blooms. A Lake Erie Case Study, 2017 Bowling Green State University
Global Solutions To Regional Problems: Collecting Global Expertise To Address The Problem Of Harmful Cyanobacterial Blooms. A Lake Erie Case Study, George S. Bullerjahn, Robert M. Mckay, Timothy W. Davis, David B. Baker, Gregory L. Boyer, Leslie V. D'Anglada, Gregory J. Doucette, Jeff C. Ho, Elena G. Irwin, Catherine L. Kling, Raphael M. Kudela, Rainer Kurmayer, Anna M. Michalak, Joseph D. Ortiz, Timothy G. Otten, Hans W. Paerl, Boqiang Qin, Brent L. Sohngen, Richard P. Stumpf, Petra M. Visser, Steven W. Wilhelm
In early August 2014, the municipality of Toledo, OH (USA) issued a ‘do not drink’ advisory on their water supply directly affecting over 400,000 residential customers and hundreds of businesses (Wilson, 2014). This order was attributable to levels of microcystin, a potent liver toxin, which rose to 2.5 mg L1 in finished drinking water. The Toledo crisis afforded an opportunity to bring together scientists from around the world to share ideas regarding factors that contribute to bloom formation and toxigenicity, bloom and toxin detection as well as prevention and remediation of bloom events. These discussions took place at ...