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2006

University of Nebraska - Lincoln

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Articles 3031 - 3046 of 3046

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Spatial Distributions Of Perchloroethylene Reactive Transport Parameters In The Borden Aquifer, Richelle M. Allen-King, Dana Divine, Michel J. L. Robin, J. Richard Alldredge, David R. Gaylord Jan 2006

Spatial Distributions Of Perchloroethylene Reactive Transport Parameters In The Borden Aquifer, Richelle M. Allen-King, Dana Divine, Michel J. L. Robin, J. Richard Alldredge, David R. Gaylord

Conservation and Survey Division

We determined the descriptive statistical and spatial geostatistical properties of the perchloroethene ln Kd and the ln k of a 1.5 m thick by 10 m horizontal transect of the Borden aquifer near the location of the Stanford-Waterloo (SW) tracer experiment. The ln Kd distribution is not normal and is right skewed because of a few high values that occur localized in two regions of the transect. In contrast, the ln k data can be characterized by a normal distribution. A linear regression of ln Kd on ln k yields a statistically significant positive correlation, also shown …

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Groundwater-Level Changes In Nebraska, Spring 2000 To Spring 2006/ Density Of Registered Irrigation Wells In Nebraska August 2005, Conservation Survey Division Jan 2006

Groundwater-Level Changes In Nebraska, Spring 2000 To Spring 2006/ Density Of Registered Irrigation Wells In Nebraska August 2005, Conservation Survey Division

Conservation and Survey Division

No abstract provided.

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Nonintrusive Mapping Of Near-Surface Preferential Flow, R. S. Freeland, Lameck O. Odhiambo, J. S. Tyner, J. T. Ammons, W. C. Wright Jan 2006

Nonintrusive Mapping Of Near-Surface Preferential Flow, R. S. Freeland, Lameck O. Odhiambo, J. S. Tyner, J. T. Ammons, W. C. Wright

Biological Systems Engineering: Papers and Publications

A unique survey protocol has been developed that maps near-subsurface preferential flow using integrated ground-penetrating radar (GPR) and a differential geographical positioning system (DGPS). The survey protocol consists of a mobile GPR system that spirals outward along a prescribed course, continuously gathering subsurface data for an extended period. Metered water is applied to a centrally located water-ponding ring, after first capturing the initial dry-state pattern signatures. The water radiates outward beneath the surface as it follows preferential flow pathways, which the GPR instrumentation spiraling above highlights. After data are collected, pre- and post-water time-elapsed images profiles are segmented by pattern …

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Variable Upper And Lower Crop Water Stress Index Baselines For Corn And Soybean, J. O. Payero, Suat Irmak Jan 2006

Variable Upper And Lower Crop Water Stress Index Baselines For Corn And Soybean, J. O. Payero, Suat Irmak

Biological Systems Engineering: Papers and Publications

Upper and lower crop water stress index (CWSI) baselines adaptable to different environments and times of day are needed to facilitate irrigation scheduling with infrared thermometers. The objective of this study was to develop dynamic upper and lower CWSI baselines for corn and soybean. Ten-minute averages of canopy temperatures from corn and soybean plots at four levels of soil water depletion were measured at North Platte, Nebraska, during the 2004 growing season. Other variables such as solar radiation (Rs), air temperature (Ta), relative humidity (RH), wind speed (u), and plant canopy height (h) were …

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Use Of Time Domain Reflectometry For Continuous Monitoring Of Nitrate-Nitrogen In Soil And Water, J. O. Payero, David D. Tarkalson, Suat Irmak Jan 2006

Use Of Time Domain Reflectometry For Continuous Monitoring Of Nitrate-Nitrogen In Soil And Water, J. O. Payero, David D. Tarkalson, Suat Irmak

Biological Systems Engineering: Papers and Publications

Nitrate-Nitrogen (NO3-N) losses to ground and surface water are an environmental and agronomic concern in modern crop production systems in the Central Great Plains. Monitoring techniques for nitrogen use in agricultural production are needed to increase crop yield, optimize nitrogen use, and reduce NO3-N leaching. Time domain reflectometry (TDR) could potentially be calibrated to continuously measure NO3-N in soil and water. The objectives of this study were to: (1) evaluate the effect of different factors affecting the response of the bulk electrical conductivity (ECb) sensed by TDR, (2) compare the sensitivity and differences between …

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A Mathematical Model For The Validation Of Safe Air-Blast Chilling Of Cooked Hams, L. J. Wang, A Amézquita, Curtis L. Weller Jan 2006

A Mathematical Model For The Validation Of Safe Air-Blast Chilling Of Cooked Hams, L. J. Wang, A Amézquita, Curtis L. Weller

Biological Systems Engineering: Papers and Publications

An integrated mathematical model of heat transfer and temperature-dependent bacterial growth was developed to validate the safety of cooked hams during air-blast chilling. Heat transfer through a cooked ham was mathematically modeled and analyzed with a finite element method. Response of bacteria to temperatures was quantitatively described using predictive microbiology. The cumulative effect of temperature history on the bacterial growth was taken into account in the model. For chilling cooked hams from 71°C to 10°C, the maximum error between the predicted and experimental core temperature was within 2.2°C, and the deviation between the predicted and measured total weight losses was …

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Properties Of Chitosan Films As A Function Of Ph And Solvent Type, Ki Myong Kim, Jeong Hwa Son, Sung-Koo Kim, Curtis L. Weller, Milford Hanna Jan 2006

Properties Of Chitosan Films As A Function Of Ph And Solvent Type, Ki Myong Kim, Jeong Hwa Son, Sung-Koo Kim, Curtis L. Weller, Milford Hanna

Biological Systems Engineering: Papers and Publications

Two different deacetylated chitosans were dissolved in formic, acetic, lactic, or propionic acid to prepare chitosan films. The pH values of the film-forming solutions were adjusted to 3, 4, and 5. Water vapor permeability (WVP), tensile strength (TS), elongation (E), and total soluble matter (TSM) were significantly (P < 0.05) affected by acid type, pH, and degree of deacetylation (DA). Low DA (LDA) chitosan films had lower WVP and TSM, higher TS compared with high DA (HDA) chitosan films. The E values were not affected by DA. As pH increased, WVP and TSM of chitosan films tended to increase while TS decreased significantly (P < 0.05). Chitosan films with acetic and propionic acid solvents had low WVP and TSM and high TS, while films with lactic acid solvent had high E and TSM and the lowest TS. Fourier-transform infrared showed peak shifting in the spectra with different solvents and at different pH values. Chitosan films with lactic acid solvent showed a peak shift to a lower frequency range. The NH3+ band was absent in the pH 5.0 chitosan film spectra.

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Modeling Of Transport Phenomena And Melting Kinetics Of Starch In A Co-Rotating Twin-Screw Extruder, Lijun Wang, David D. Jones, Curtis L. Weller, Milford Hanna Jan 2006

Modeling Of Transport Phenomena And Melting Kinetics Of Starch In A Co-Rotating Twin-Screw Extruder, Lijun Wang, David D. Jones, Curtis L. Weller, Milford Hanna

Biological Systems Engineering: Papers and Publications

A mathematical model was developed to simulate fluid flow, heat transfer, and melting kinetics of starch in a co-rotating intermeshing twin-screw extruder (TSE). The partial differential equations governing the transport phenomena of the biomaterial in the extruder were solved by a finite element scheme. For validating the model, the predicted product pressure, bulk temperature at the entrance of the die, and minimum residence time of the biomaterial in the extruder were compared with experimental data. Standard errors of product pressure, bulk temperature at the die entrance, and minimum residence time were about 8.8, 2.8, and 17.3%. Simulations were carried out …

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Postharvest Treatment To Control Codling Moth In Fresh Apples Using Water Assisted Radio Frequency Heating, Shaojin Wang, Sohan Birla, J. D. Hansen Jan 2006

Postharvest Treatment To Control Codling Moth In Fresh Apples Using Water Assisted Radio Frequency Heating, Shaojin Wang, Sohan Birla, J. D. Hansen

Biological Systems Engineering: Papers and Publications

Apples destined for export to Japan and South Korea are currently disinfested for codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), using methyl bromide fumigation. Restrictions and limitations imposed on the uses of methyl bromide have increased interest in developing alternative non-chemical quarantine treatments. It is imperative that the treatment is effective against codling moth yet maintains the quality of treated apples. The present study explored the application of radio frequency (RF) energy in conjunction with conventional hot water treatment to develop feasible heat treatments. Treatment parameters were selected based on minimum time–temperature conditions required for 100% mortality of fifth-instar codling …

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Laughter-Piece Theatre: Humor As A Systematic Teaching Tool, Ronald A. Berk Jan 2006

Laughter-Piece Theatre: Humor As A Systematic Teaching Tool, Ronald A. Berk

Professional and Organizational Development Network in Higher Education: Archives

Humor can be used to bring students and deadly boring content to life. It can hook your students, engage their emotions, and focus their minds and eyeballs on learning.

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Leveling The Field: Using Rubrics To Achieve Greater Equity In Teaching And Grading, Dannelle D. Stevens, Antonia Levi Jan 2006

Leveling The Field: Using Rubrics To Achieve Greater Equity In Teaching And Grading, Dannelle D. Stevens, Antonia Levi

Professional and Organizational Development Network in Higher Education: Archives

Rubrics can be used to assure greater consistency in grading and as a teaching tool to promote greater equity, especially with students who are first generation and /or non-native speakers of English.

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Student Teams, Teaching, And Technology, Ruth Federman Stein, Sandra N. Hurd Jan 2006

Student Teams, Teaching, And Technology, Ruth Federman Stein, Sandra N. Hurd

Professional and Organizational Development Network in Higher Education: Archives

Using student teams in the classroom actively involves students in the learning process. This essay describes the planning necessary for effective use of teams and the impact of technology on the team learning environment.

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Practice Tests: A Practical Teaching Method, Margaret K. Snooks Jan 2006

Practice Tests: A Practical Teaching Method, Margaret K. Snooks

Professional and Organizational Development Network in Higher Education: Archives

Learn about the development, implementation and evaluation of short daily practice tests. Student response is overwhelmingly positive, and learning improvement is evidenced by higher semester averages.

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Using Student-Centered Assessment To Enhance Learning, Joseph "Mick" Lalopa Jan 2006

Using Student-Centered Assessment To Enhance Learning, Joseph "Mick" Lalopa

Professional and Organizational Development Network in Higher Education: Archives

Student-centered assessment allows students to participate in their growth as learners and helps build valuable self-assessment skills.

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From Passive To Active Learning: Helping Students Make The Shift, Marilla Svinicki Jan 2006

From Passive To Active Learning: Helping Students Make The Shift, Marilla Svinicki

Professional and Organizational Development Network in Higher Education: Archives

Being active and self-directed as a learner makes for better learning and retention, but what does that mean for students and for instruction?

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Assessing Students’ Online Learning: Strategies And Resources, Patricia Comeaux Jan 2006

Assessing Students’ Online Learning: Strategies And Resources, Patricia Comeaux

Professional and Organizational Development Network in Higher Education: Archives

Explore key strategies used by experienced online instructors, and learn about the wealth of resources for designing assessment instruments integral to online learning.

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