Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

2013

Discipline
Institution
Keyword
Publication
Publication Type
File Type

Articles 28831 - 28860 of 29710

Full-Text Articles in Entire DC Network

Bacillus Thuringiensis: Transgenic Crops, Julie A. Peterson, John J. Obrycki, James D. Harwood Jan 2013

Bacillus Thuringiensis: Transgenic Crops, Julie A. Peterson, John J. Obrycki, James D. Harwood

Department of Entomology: Faculty Publications

Bacillus thuringiensis (Bt) crops, genetically modified to express insecticidal toxins that target key pests of corn, cotton, rice, potato, and other crops, have been rapidly adopted and have become dominant fixtures in agroecosystems throughout the world. Due to the constitutive nature of Bt toxin expression, insecticidal proteins may be found in nearly all plant tissues, presenting multiple sources for Bt toxins to enter the environment, thus creating complex direct and indirect pathways for non-target organisms to be exposed to insecticidal proteins. The environmental impacts of Bt crops have been widely debated, although both benefits and risks do exist. Benefits of …


Azimuthal Anisotropy Of Π⁰ And Η Mesons In Au + Au Collisions At √Snn=200, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann Jan 2013

Azimuthal Anisotropy Of Π⁰ And Η Mesons In Au + Au Collisions At √Snn=200, Andrew Marshall Adare, Gyöngyi Baksay, László A. Baksay, Marcus Hohlmann

Aerospace, Physics, and Space Science Faculty Publications

The azimuthal anisotropy coefficients v₂ and v₄ of π⁰ and η mesons are measured in Au + Au collisions at √sNN=200 GeV as a function of transverse momentum pT (1-14 GeV/c) and centrality. The extracted v₂ coefficients are found to be consistent between the two meson species over the measured pT range. The ratio of v₄/v₂² for π⁰ mesons is found to be independent of pT for 1-9 GeV/c, implying a lack of sensitivity of the ratio to the change of underlying physics with pT. Furthermore, the ratio of v₄/v₂² is systematically larger in central collisions, which may reflect the …


Radio Emissions From Terrestrial Gamma-Ray Flashes, Joseph R. Dwyer, Steven A. Cummer Jan 2013

Radio Emissions From Terrestrial Gamma-Ray Flashes, Joseph R. Dwyer, Steven A. Cummer

Aerospace, Physics, and Space Science Faculty Publications

The theory of radio frequency (RF) emissions by terrestrial gamma-ray flashes (TGFs) is developed. These radio emissions, which are separate from the emission caused by lightning, are produced by the electric currents generated by runaway electrons and resulting low-energy electrons and ions. It is found from theory that the radio frequency pulses produced by TGFs are large enough to measure. Features of these signals depend strongly on certain aspects of the runaway acceleration process and so should provide additional information about the source mechanism(s) of this interesting atmospheric phenomenon. The RF emissions from several TGF models are calculated and compared …


The Angular Distribution Of Energetic Electron And X-Ray Emissions From Triggered Lightning Leaders, M. M. Schaal, Joseph R. Dwyer, Hamid K. Rassoul, Jonathan David Hill, Douglas M. Jordan, Martin A. Uman Jan 2013

The Angular Distribution Of Energetic Electron And X-Ray Emissions From Triggered Lightning Leaders, M. M. Schaal, Joseph R. Dwyer, Hamid K. Rassoul, Jonathan David Hill, Douglas M. Jordan, Martin A. Uman

Aerospace, Physics, and Space Science Faculty Publications

We investigate individual X-ray bursts from lightning leaders to determine if energetic electrons at the source (and hence X-rays) are emitted isotropically or with some degree of anisotropy. This study was motivated by the work of Saleh et al. (2009), which found the falloff of X-rays in concentric radial annuli, covering all azimuthal directions in each annulus, from the lightning channel to be most consistent with an isotropic electron source. Here we perform a statistical analysis of angular and spatial distributions of X-rays measured by up to 21 NaI/PMT detectors at the International Center for Lightning Research and Testing site …


Radio Signals From Electron Beams In Terrestrial Gamma Ray Flashes, Valerie Connaughton, Joseph R. Dwyer, Eric Cramer Jan 2013

Radio Signals From Electron Beams In Terrestrial Gamma Ray Flashes, Valerie Connaughton, Joseph R. Dwyer, Eric Cramer

Aerospace, Physics, and Space Science Faculty Publications

We show that the rate of association between terrestrial gamma ray flashes (TGFs) observed by the Fermi gamma ray burst monitor and VLF discharges detected by the World Wide Lightning Location Network (WWLLN) depends strongly on the duration of the TGF, with the shortest TGFs having associated WWLLN events over 50% of the time, and the longest TGFs showing a less than 10% match rate. This correlation is stronger if one excludes the WWLLN discharges that are not simultaneous (within 200 ms) with the TGF. We infer that the simultaneous VLF discharges are from the relativistic electron avalanches that are …


Concept Design In Virtual Reality Of A Forestry Trailer Using A Qfd-Triz Based Approach, Kenan Melemez, Giuseppe Di Gironimo, Gianpiero Esposito, Antonio Lanzotti Jan 2013

Concept Design In Virtual Reality Of A Forestry Trailer Using A Qfd-Triz Based Approach, Kenan Melemez, Giuseppe Di Gironimo, Gianpiero Esposito, Antonio Lanzotti

Turkish Journal of Agriculture and Forestry

Trailers are used to carry logs having specific dimensions for logging extraction operations, secondary transportation, and agricultural activities. The main objective of this study was the design of a timber trailer capable of manual loading operations and suitable for rough terrain conditions to be used in combination with a farm tractor in the western Black Sea region of Turkey. In the proposed methodology, a House of Quality diagram was used to transfer customer requirements into quality characteristics, and focus the development of the product toward customer satisfaction. Negative correlations between quality characteristics were solved using the TRIZ contradiction toolkit and …


Extraction Of Phenolic Compounds From Melissa Using Microwave And Ultrasound, Alev Emi̇ne İnce, Serpi̇l Şahi̇n, Servet Gülüm Şümnü Jan 2013

Extraction Of Phenolic Compounds From Melissa Using Microwave And Ultrasound, Alev Emi̇ne İnce, Serpi̇l Şahi̇n, Servet Gülüm Şümnü

Turkish Journal of Agriculture and Forestry

In this study, extraction of phenolic compounds from melissa by microwave and ultrasound was studied. In both the microwave and ultrasound extractions, the effects of extraction time (5-20 min for microwave; 5-30 min for ultrasound) and solid-to-solvent ratio (1:10, 1:20, and 1:30 g mL^{-1}) on total phenolic content (TPC) were investigated. Effects of different powers (50% and 80%) were also studied for the ultrasound extraction. As a solvent, water was used. In microwave extractions, the highest TPC of extracts (145.8 mg GAE g^{-1} dry material) was obtained in 5 min and at a 1:30 solid-to-solvent ratio. For ultrasound extraction, the …


An Efficient Multiplex Pcr Assay For Early Detection Of Agrobacterium Tumefaciens In Transgenic Plant Materials, Li Yang, Changchun Wang, Lihuan Wang, Changjie Xu, Kunsong Chen Jan 2013

An Efficient Multiplex Pcr Assay For Early Detection Of Agrobacterium Tumefaciens In Transgenic Plant Materials, Li Yang, Changchun Wang, Lihuan Wang, Changjie Xu, Kunsong Chen

Turkish Journal of Agriculture and Forestry

The multiplex polymerase chain reaction (MPCR) is a variant of conventional PCR in which 2 or more target sequences are amplified by more than 1 pair of primers in a single reaction mixture. In this study, an efficient MPCR assay was established and optimized for the quick detection of Agrobacterium-derived plant transformants. The neomycin phosphotransferase II gene fragment (nptII; target gene) and the chromosomal virulence gene ChvA fragment of Agrobacterium tumefaciens (external reference gene) were amplified simultaneously with 2 pairs of corresponding primers. The MPCR results showed that 9 out of 10 kanamycin-resistant lines tested were transformed with the foreign …


Selection Of Potential Autochthonous Starter Cultures From Shalgam, A Traditional Turkish Lactic Acid-Fermented Beverage, Hasan Tangüler, Hüseyi̇n Erten Jan 2013

Selection Of Potential Autochthonous Starter Cultures From Shalgam, A Traditional Turkish Lactic Acid-Fermented Beverage, Hasan Tangüler, Hüseyi̇n Erten

Turkish Journal of Agriculture and Forestry

The present study was done to select the potential autochthonous lactic acid bacteria (LAB) for the production of shalgam, which is a traditional Turkish lactic acid-fermented beverage. Eighteen LAB belonging to the genera Lactobacillus, Lactococcus, Pediococcus, and Leuconostoc isolated previously from shalgam samples produced in the university laboratory and by small- and large-scale producers in industry were used. Pasteurized black carrot juice was inoculated individually with these selected LAB strains and fermented for 10 days. The strains of Lb. plantarum gave the highest numbers during fermentations with a range of 9.40-9.16 log cfu mL^{-1}. Lb. plantarum^{bx} produced the highest total …


Support Vector Machines In Wood Identification: The Case Of Three Salix Species From Turkey, Kemal Turhan, Bedri̇ Serdar Jan 2013

Support Vector Machines In Wood Identification: The Case Of Three Salix Species From Turkey, Kemal Turhan, Bedri̇ Serdar

Turkish Journal of Agriculture and Forestry

The aim of this study was to use a support vector machine (SVM) for the first time as a predictive method for differentiating species of Salix wood through the biometric analysis of their anatomy using wood taken from basal disks of 3 species. The purpose of a SVM is to construct optimal decision boundaries among classes in a decision plane. A decision plane separates a set of objects having different class memberships. In this study, the decision plane has 3 different wood species. Timely and accurate identification of tree species can be crucial in forestry. The similarity of structures in …


Withdrawal Force Capacity Of Mortise And Loose Tenon T-Type Furniture Joints, Mohammad Derikvand, Jerzy Smardzewski, Ghanbar Ebrahimi, Mosayeb Dalvand, Sadegh Maleki Jan 2013

Withdrawal Force Capacity Of Mortise And Loose Tenon T-Type Furniture Joints, Mohammad Derikvand, Jerzy Smardzewski, Ghanbar Ebrahimi, Mosayeb Dalvand, Sadegh Maleki

Turkish Journal of Agriculture and Forestry

The main goal of this study was to determine the effect of wood species and loose tenon length on the withdrawal force capacity of mortise and loose tenon (M<) T-type furniture joints. The specimens were manufactured from oak (Quercus alba), beech (Fagus orientalis L.), poplar (Populus deltoides), sycamore (Platanus orientalis), fir (Abies alba), and white walnut (Juglans cinerea), and the tenon species selected was oriental beech (Fagus orientalis L.). The length of the tenon was determined on the basis of the length glued into the horizontal member of the joint. The lengths in the present study were 10, 20, and …


Physicochemical And Rheological Characteristics Of Alcohol Free Probiotic Boza Produced Using Lactobacillus Casei Shirota: Estimation Of Apparent Viscosity Of Boza Using Non-Linear Modeling Techniques, İsmet Öztürk, Safa Karaman, Fati̇h Törnük, Osman Sağdiç Jan 2013

Physicochemical And Rheological Characteristics Of Alcohol Free Probiotic Boza Produced Using Lactobacillus Casei Shirota: Estimation Of Apparent Viscosity Of Boza Using Non-Linear Modeling Techniques, İsmet Öztürk, Safa Karaman, Fati̇h Törnük, Osman Sağdiç

Turkish Journal of Agriculture and Forestry

The effects of fermentation with 2 different starter culture mixtures composed of lactic acid bacteria (LAB) on some physicochemical, microbiological, sensorial, and rheological characteristics of boza, a traditional fermented Turkish beverage, during storage for 10 days at 8 ^°C were investigated. Lb. casei Shirota adapted in boza well and provided the boza with a probiotic property. At the beginning of storage, the Lb. casei Shirota count of boza was 6.83 log cfu mL^{-1}, while total LAB counts were 8.01 and 8.11 log cfu mL-1 for S1 and S2 samples, respectively. A decrease in pH values was observed when the counts …


Effects Of Posttreatment With Alkaline Copper Quat And Copper Azole On The Mechanical Properties Of Wood-Based Composites, Ci̇hat Taşçioğlu Jan 2013

Effects Of Posttreatment With Alkaline Copper Quat And Copper Azole On The Mechanical Properties Of Wood-Based Composites, Ci̇hat Taşçioğlu

Turkish Journal of Agriculture and Forestry

The static bending strengths, modulus of rupture, and modulus of elasticity of 5 commercial wood-based composites [softwood plywood (SWP), hardwood plywood (HWP), medium density fiber-board (MDF), oriented strand board (OSB), and particleboard (PB)] were measured after a postmanufacture treatment of vacuum-impregnation with alkaline copper quat (ACQ) and copper azole (CA) (target retentions: 0.65, 1.30, and 2.60 kg^{ m-3} for ACQ; 0.25, 0.50, and 1.0 kg ^{m-3} for CA). Of the composites tested, SWP exceptionally sustained no damage to its bending strengths, regardless of preservative types and retentions. Others (HWP, MDF, OSB, and PB) were necessarily affected to some degree by …


Utilization Of Color Parameters To Estimate Moisture Content And Nutrient Levels Of Peanut Leaves, Muharrem Keski̇n, Sema Karanlik, Serap Görücü Keski̇n, Yurtsever Soysal Jan 2013

Utilization Of Color Parameters To Estimate Moisture Content And Nutrient Levels Of Peanut Leaves, Muharrem Keski̇n, Sema Karanlik, Serap Görücü Keski̇n, Yurtsever Soysal

Turkish Journal of Agriculture and Forestry

Leaf nutrient levels are traditionally quantified by laboratory chemical analysis, which is time-consuming and requires intensive labor and investment. The objective of this study was to predict the moisture content (MC) and nutrient content of peanut leaves from color parameters (CIE Lab) using a chromameter. This method is faster and requires less labor and investment compared to laboratory chemical analysis. Fifty peanut leaf samples were collected from a commercial peanut field. The samples were analyzed for MC, N, P, K, Ca, Mg, Fe, Mn, Zn, and Cu concentrations after color parameters were acquired by chromameter. A positive and high correlation …


Is Quercus Virgiliana A Distinct Morphological And Genetic Entity Among European White Oaks?, Cristian Mihai Enescu, Alexandru Lucian Curtu, Neculae Şofletea Jan 2013

Is Quercus Virgiliana A Distinct Morphological And Genetic Entity Among European White Oaks?, Cristian Mihai Enescu, Alexandru Lucian Curtu, Neculae Şofletea

Turkish Journal of Agriculture and Forestry

The existence of Quercus virgiliana Ten. is a subject of debate among botanists and silviculturists. It was considered a distinct species, sometimes as an intraspecific taxonomic unit of Q. pubescens L., or was not even recognized as a taxon or infrataxon. This disagreement with regard to the taxonomic classification is explained by the morphological similarities between Q. virgiliana and Q. pubescens, with a small overlap between particular leaf and fruit traits. The main objective of this study was to evaluate the macromorphological fruit and leaf descriptors in Romanian populations of pubescent oaks. We wanted to find which traits discriminate between …


Cover And Contents Jan 2013

Cover And Contents

Turkish Journal of Agriculture and Forestry

No abstract provided.


Photographic Survey Of Benthos Provides Insights Into The Antarctic Fish Fauna From The Marguerite Bay Slope And The Amundsen Sea, Joseph T. Eastman, Margaret O. Amsler, Richard D. Aronson, Sven Thatje, James Mcclintock, Stephanie C. Vos, Jeffrey W. Kaeli, Hanumant Singh, Mario La Mesa Jan 2013

Photographic Survey Of Benthos Provides Insights Into The Antarctic Fish Fauna From The Marguerite Bay Slope And The Amundsen Sea, Joseph T. Eastman, Margaret O. Amsler, Richard D. Aronson, Sven Thatje, James Mcclintock, Stephanie C. Vos, Jeffrey W. Kaeli, Hanumant Singh, Mario La Mesa

Ocean Engineering and Marine Sciences Faculty Publications

We reviewed photographic images of fishes from depths of 381–2282m in Marguerite Bay and 405–2007m in the Amundsen Sea. Marguerite Bay fishes were 33% notothenioids and 67% non-notothenioids. Channichthyids (47%) and nototheniids (44%) were the most abundant notothenioids. The deep-living channichthyid Chionobathyscus dewitti (74%) and the nototheniid genus Trematomus (66%) were the most abundant taxa within these two families. The most abundant non-notothenioids were the macrourid Macrourus whitsoni (72%) and zoarcids (18%). Amundsen Sea fishes were 87% notothenioids and 13% non-notothenioids, the latter exclusively Macrourus whitsoni. Bathydraconids (38%) and artedidraconids (30%) were the most abundant notothenioids. We observed that Macrourus …


Feral Cat Management, Christopher A. Lepcyzk, Sheila Conant, David Duffy, David M. Bird, Michael Calver, Fern P. Duval, Michael Hutchins, Cheryl A. Lohr, Kerrie Anne Loyd, Peter P. Marra, William C. Pitt, Grant Sizemore, Rachel Sprague, Stanley A. Temple, Yolanda Van Heezik, George Wallace Jan 2013

Feral Cat Management, Christopher A. Lepcyzk, Sheila Conant, David Duffy, David M. Bird, Michael Calver, Fern P. Duval, Michael Hutchins, Cheryl A. Lohr, Kerrie Anne Loyd, Peter P. Marra, William C. Pitt, Grant Sizemore, Rachel Sprague, Stanley A. Temple, Yolanda Van Heezik, George Wallace

United States Department of Agriculture Wildlife Services: Staff Publications

We applaud McCarthy et al for their research addressing a critical issue in feral cat management. We concur that feral and free-roaming cats pose myriad problems for people and the environment. However, we believe that the authors overlooked several important factors when concluding that trap-vasectomy- hysterectomy-release (IVHR) "should be recommended as a humane and more effective method of decreasing population size."

First, the population model used in the study does not represent a typical managed feral cat colony. Inclusion of self-imposed restraints on colony size attributable to a hypothetical carrying capacity restricts the population from reacting naturally to resources or …


Intranasal Inoculation Of White-Tailed Deer (Odocoileus Virginianus) With Lyophilized Chronic Wasting Disease Prion Particulate Complexed To Montmorillonite Clay, Tracy A. Nichols, Terry R. Spraker, Tara D. Rigg, Crystal Meyerett-Reid, Clare Hoover, Brady Michel, Jifeng Bian, Edward Hoover, Thomas Gidlewski, Aru Balachandran, Katherine O'Rourke, Glenn C. Telling, Richard Bowen, Mark D. Zabel, Kurt C. Vercauteren Jan 2013

Intranasal Inoculation Of White-Tailed Deer (Odocoileus Virginianus) With Lyophilized Chronic Wasting Disease Prion Particulate Complexed To Montmorillonite Clay, Tracy A. Nichols, Terry R. Spraker, Tara D. Rigg, Crystal Meyerett-Reid, Clare Hoover, Brady Michel, Jifeng Bian, Edward Hoover, Thomas Gidlewski, Aru Balachandran, Katherine O'Rourke, Glenn C. Telling, Richard Bowen, Mark D. Zabel, Kurt C. Vercauteren

United States Department of Agriculture Wildlife Services: Staff Publications

Chronic wasting disease (CWD), the only known prion disease endemic in wildlife, is a persistent problem in both wild and captive North American cervid populations. This disease continues to spread and cases are found in new areas each year. Indirect transmission can occur via the environment and is thought to occur by the oral and/or intranasal route. Oral transmission has been experimentally demonstrated and although intranasal transmission has been postulated, it has not been tested in a natural host until recently. Prions have been shown to adsorb strongly to clay particles and upon oral inoculation the prion/clay combination exhibits increased …


Generalized Analytic Fourier-Feynman Transform Of Functionals In A Banach Algebra F_(A1,A2)^(A,B), Jae Gil Choi, David Skough, Seung Jun Chang Jan 2013

Generalized Analytic Fourier-Feynman Transform Of Functionals In A Banach Algebra F_(A1,A2)^(A,B), Jae Gil Choi, David Skough, Seung Jun Chang

Department of Mathematics: Faculty Publications

We introduce the Fresnel type class F_(A1,A2)^(a,b).We also establish the existence of the generalized analytic Fourier-Feynman transform for functionals in the Banach algebra F_(A1,A2)^(a,b).


Regions, Ernesto Alvarado, Diana Damschroder, Alyssa Antoniskis, Gabriel Auteri, Anusree Garg, Emily Singer Hurvitz, Christa Elliott, Tyler Addison Jan 2013

Regions, Ernesto Alvarado, Diana Damschroder, Alyssa Antoniskis, Gabriel Auteri, Anusree Garg, Emily Singer Hurvitz, Christa Elliott, Tyler Addison

Human Rights Brief

No abstract provided.


Nonlinear Control For Dual Quaternion Systems, William D. Price Jan 2013

Nonlinear Control For Dual Quaternion Systems, William D. Price

Doctoral Dissertations and Master's Theses

The motion of rigid bodies includes three degrees of freedom (DOF) for rotation, generally referred to as roll, pitch and yaw, and 3 DOF for translation, generally described as motion along the x, y and z axis, for a total of 6 DOF. Many complex mechanical systems exhibit this type of motion, with constraints, such as complex humanoid robotic systems, multiple ground vehicles, unmanned aerial vehicles (UAVs), multiple spacecraft vehicles, and even quantum mechanical systems. These motions historically have been analyzed independently, with separate control algorithms being developed for rotation and translation. The goal of this research is to study …


Dynamics And Control Of Higher-Order Nonholonomic Systems, Jaime Rubio HerváS Jan 2013

Dynamics And Control Of Higher-Order Nonholonomic Systems, Jaime Rubio HerváS

Doctoral Dissertations and Master's Theses

A theoretical framework is established for the control of higher-order nonholonomic systems, defined as systems that satisfy higher-order nonintegrable constraints. A model for such systems is developed in terms of differential-algebraic equations defined on a higher-order tangent bundle. A number of control-theoretic properties such as nonintegrability, controllability, and stabilizability are presented. Higher-order nonholonomic systems are shown to be strongly accessible and, under certain conditions, small time locally controllable at any equilibrium. There are important examples of higher-order nonholonomic systems that are asymptotically stabilizable via smooth feedback, including space vehicles with multiple slosh modes and Prismatic-Prismatic-Revolute (PPR) robots moving open liquid …


Some Insights For The Prediction Of Near-Wall Turbulence, Farid Karimpour, Subhas K. Venayagamoorthy Jan 2013

Some Insights For The Prediction Of Near-Wall Turbulence, Farid Karimpour, Subhas K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this paper, we revisit the eddy viscosity formulation to highlight a number of important issues that have direct implications for the prediction of near-wall turbulence. For steady wall-bounded turbulent flows, we make the equilibrium assumption between rates of production (P) and dissipation (ε) of turbulent kinetic energy (κ) in the near-wall region to propose that the eddy viscosity should be given by vt ε/S2, where S is the mean shear rate. We then argue that the appropriate velocity scale is given by (STL)-1/2 k1/2 where TL = k ε is the turbulence (decay) time scale. The …


Distinguishing Between Yield Advances And Yield Plateaus In Historical Crop Production Trends, Patricio Grassini, Kent M. Eskridge, Kenneth Cassman Jan 2013

Distinguishing Between Yield Advances And Yield Plateaus In Historical Crop Production Trends, Patricio Grassini, Kent M. Eskridge, Kenneth Cassman

Department of Agronomy and Horticulture: Faculty Publications

Food security and land required for food production largely depend on rate of yield gain of major cereal crops. Previous projections of food security are often more optimistic than what historical yield trends would support. Many econometric projections of future food production assume compound rates of yield gain, which are not consistent with historical yield trends. Here we provide a framework to characterize past yield trends and show that linear trajectories adequately describe past yield trends, which means the relative rate of gain decreases over time. Furthermore, there is evidence of yield plateaus or abrupt decreases in rate of yield …


New Technologies Reduce Greenhouse Gas Emissions From Nitrogenous Fertilizer In China, Wei-Feng Feng, Zheng-Xia Dou, Pan He, Xiao-Tang Ju, David Powlson, Dave Chadwick, David Norse, Yue-Lai Lu, Ying Zhang, Liang Wu, Xin-Ping Chen, Kenneth Cassman, Fu-Suo Zhang Jan 2013

New Technologies Reduce Greenhouse Gas Emissions From Nitrogenous Fertilizer In China, Wei-Feng Feng, Zheng-Xia Dou, Pan He, Xiao-Tang Ju, David Powlson, Dave Chadwick, David Norse, Yue-Lai Lu, Ying Zhang, Liang Wu, Xin-Ping Chen, Kenneth Cassman, Fu-Suo Zhang

Department of Agronomy and Horticulture: Faculty Publications

Synthetic nitrogen (N) fertilizer has played a key role in enhancing food production and keeping half of the world’s population adequately fed. However, decades of N fertilizer overuse in many parts of the world have contributed to soil, water, and air pollution; reducing excessive N losses and emissions is a central environmental challenge in the 21st century. China’s participation is essential to global efforts in reducing N-related greenhouse gas (GHG) emissions because China is the largest producer and consumer of fertilizer N. To evaluate the impact of China’s use of N fertilizer, we quantify the carbon footprint of China’s N …


Scale Of Fluctuation Of Geotechnical Parameters Estimated From Cptu And Laboratory Test Data, Site Onyejekwe, Louis Ge Jan 2013

Scale Of Fluctuation Of Geotechnical Parameters Estimated From Cptu And Laboratory Test Data, Site Onyejekwe, Louis Ge

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

For a complete probabilistic characterization of a geotechnical parameter, its mean, variance, and the scale of fluctuation have to be known. While the mean and variance can be easily determined, determination of the scale of fluctuation is a little more complex. Knowledge of the scale of fluctuation is important in reliability-based design as it is used in implementing spatial averaging and computing the variance-reduction factor. Published values of scale of fluctuation of geotechnical parameters are based on widely sourced data and hence may not be most appropriate for local situations. Based on 11 CPTu soundings and laboratory test results of …


Probability Of Failure For Slopes With Sensitivity Analysis, Michelle Deng, Ronaldo Luna Jan 2013

Probability Of Failure For Slopes With Sensitivity Analysis, Michelle Deng, Ronaldo Luna

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The significance of random variables on the probability of failure of slopes is generally evaluated by changing a different set of values for each variable and repeating the approach several times to conclude a trend. This method is very straightforward but requires time and computational resources; and it is inefficient especially when the number of random variables is large. This paper presents an analysis approach in which the sensitivity analysis is introduced to quantify the influence of the random variables on the probability of failure for slopes. In this study, the factor of safety of the slope was determined using …


Performance-Based Seismic Design Of Unbonded Precast Post-Tensioned Concrete Filled Gfrp Tube Piers, Haitham M. Dawood, Mohamed Elgawady Jan 2013

Performance-Based Seismic Design Of Unbonded Precast Post-Tensioned Concrete Filled Gfrp Tube Piers, Haitham M. Dawood, Mohamed Elgawady

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper presents a seismic design procedure for self-centering precast post-tensioned bridge piers. The piers presented in this manuscript consisted of concrete filled fiber reinforced polymer (FRP) tubes. A large set of 84 piers with different design parameters were analyzed using finite element models. The backbone curve of each pier was developed and bilinearized. The idealized backbone curves were used to develop a set of empirical equations that were able to reproduce the bilinearized backbone curve of a given pier. Different performance criteria have been proposed for the system according to the intensity and the frequency of occurrence of a …


Effect Of Fly Ash On The Shear Strength Of Concrete Beams Without Shear Reinforcement, Mahdi Arezoumandi, Jeffery S. Volz, Carlos A. Ortega Jan 2013

Effect Of Fly Ash On The Shear Strength Of Concrete Beams Without Shear Reinforcement, Mahdi Arezoumandi, Jeffery S. Volz, Carlos A. Ortega

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The following paper presents the results of an experimental investigation of the shear strength of full-scale reinforced concrete beams constructed with both high-volume fly ash concrete (HVFAC)-concrete with at least 50% of the cement replaced with fly ash-and conventional concrete (CC). This study includes two HVFAC mixes and one CC mix. The two HVFAC mixes are identical except for the amount of Class C fly ash replacement of cement, with one mix replacing 50% of the cement with fly ash and the other replacing 70 %. The test matrix included 18 beams-six for each concrete type-with three different longitudinal reinforcement …