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Retrospective Theses and Dissertations

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Full-Text Articles in Life Sciences

Characterization Of Barley Yellow Dwarf Virus Subgenomic Rnas, Jacquelyn R. Jackson Jan 2008

Characterization Of Barley Yellow Dwarf Virus Subgenomic Rnas, Jacquelyn R. Jackson

Retrospective Theses and Dissertations

Transcription of subgenomic RNAs (sgRNAs) is a common strategy used by many positive strand RNA viruses of plants and animals to regulate viral gene expression. Barley yellow dwarf virus (BYDV) produces three nested 3'-coterminal subgenomic RNAs in infected cells. SgRNA1 serves as the messenger for the structural and movement proteins. sgRNA2 encodes a small open reading frame (ORF6), that appears not to be translated. The role of sgRNA3 is unknown, as it encodes no ORFs. Neither sgRNA2 nor sgRNA3 is needed for BYDV RNA replication in oat protoplasts. However, sgRNA2 does function as a riboregulator of viral translation in ...


Nutrient Recycling In Biofuel Production Systems: Biomass Ash Pelleting, Ethanol Co-Product Allocation, And A Beef-Ethanol Production System Analysis, Katherine A. Edwards Jan 2008

Nutrient Recycling In Biofuel Production Systems: Biomass Ash Pelleting, Ethanol Co-Product Allocation, And A Beef-Ethanol Production System Analysis, Katherine A. Edwards

Retrospective Theses and Dissertations

Relative to fossil fuels, biofuels help to close the carbon cycle; however other essential nutrient cycles remain open. When biomass is removed from the agricultural landscape for biofuel production, essential plant nutrients such as nitrogen (N), phosphorus (P), and potassium (K) are also removed and concentrate in biorefinery waste streams and low value co-products. This thesis comprises three analyses related to nutrient cycles in the emerging bioeconomy. In the first, combusted biomass ash was pelleted and evaluated as a potential fertilizer. In the second, an energy co-product credit for corn dry grind ethanol production has been determined by examining the ...


Postconflict And Conflict Behavior In All-Male Groups Of Captive Western Lowland Gorillas (Gorilla Gorilla Gorilla), Jackie Elizabeth Davenport Jan 2008

Postconflict And Conflict Behavior In All-Male Groups Of Captive Western Lowland Gorillas (Gorilla Gorilla Gorilla), Jackie Elizabeth Davenport

Retrospective Theses and Dissertations

I studied male western lowland gorillas (Gorilla gorilla gorilla) in a captive setting in order to determine if post-conflict reconciliation exists in male-male dyads of this species. I also examined conflict itself in order to determine the consequences of housing these males together in all-male groups in captivity. This was accomplished by examining the behaviors of nine male gorillas at the Henry-Doorly Zoo in Omaha, Nebraska. Data that I recorded included post-conflict observations, social interactions, and activity budgets. I analyzed the data in order to determine levels of reconciliation, welfare of the population, and comparisons with wild conspecifics. I hypothesized ...


Comparison Of Esn, Urea, And Aqua Ammonia As Sources Of Nitrogen For Corn Production In Iowa, Jeffrey Allen Moore Jan 2008

Comparison Of Esn, Urea, And Aqua Ammonia As Sources Of Nitrogen For Corn Production In Iowa, Jeffrey Allen Moore

Retrospective Theses and Dissertations

Three nitrogen response studies were conducted in Iowa to compare the effect of a controlled release fertilizer, ESN, to urea and aqua ammonia (AA), on corn grain yields, biomass yields, and soil nitrate (NO3 --N) and ammonium (NH4+-N) concentrations. Experiments were conducted at two sites from 2003 through 2007 for the spring-applied ESN/urea study, two sites from 2006 through 2007 for the fall and spring-applied ESN/AA study, and one site from 2006 through 2007 for the spring applied ESN/AA study. N rates in the studies were 0-202 kg ha-1 in 34 kg N ha-1 increments in ...


Genetic Regulation Of The Healthfulness Of Beef Fatty Acid Composition, Shu Zhang Jan 2008

Genetic Regulation Of The Healthfulness Of Beef Fatty Acid Composition, Shu Zhang

Retrospective Theses and Dissertations

The effects of genetic factors, such as breed and single nucleotide polymorphisms (SNPs), on beef fatty acid composition were investigated in the current study. The first objective was to identify single nucleotide polymorphisms (SNPs) in the thioesterase (TE) domain of bovine fatty acid synthase (FASN) gene and evaluate the extent to which they were associated with beef fatty acid composition. The four exons in FASN that encode for TE were sequenced, and three SNPs, AF285607:g.17924A>G, g.18663T>C, and g.18727C>T, were identified. Purebred Angus bulls (n = 331) were classified into three genotype groups, AA (n ...


Identification And Characterization Of Genes Responsible For High Persistence In Salmonella Enterica Serovar Typhimurium, Alec Demars Houlihan Victorsen Jan 2008

Identification And Characterization Of Genes Responsible For High Persistence In Salmonella Enterica Serovar Typhimurium, Alec Demars Houlihan Victorsen

Retrospective Theses and Dissertations

The ability of bacteria to survive lethal challenges of antibiotics, and other environmental stresses, is known as persistence. To better understand the genetic basis of persistence, we have isolated new mutants of Salmonella enterica serovar Typhimurium that show an increased level of persistence to antibiotic exposure. We have also developed a novel technique utilizing recombineering to retrofit Tn10d transposons with an origin of replication in order to map their insertion site. This technique allowed us to map and characterize two loci which are capable of causing high persistence in S. enterica. One locus includes two previously uncharacterized genes (STM4528 and ...


Functional Analysis Of The C-Terminal Domain In The Drosophila Jil-1 Histone H3 Kinase, Xiaomin Bao Jan 2008

Functional Analysis Of The C-Terminal Domain In The Drosophila Jil-1 Histone H3 Kinase, Xiaomin Bao

Retrospective Theses and Dissertations

Epigenetic regulation is an important process utilized by biological systems to control gene expression and organize development, with histone modification enzymes among the most important components in this regulatory network. The predominant interphase H3 Serine10 kinase in Drosophila is JIL-1, which plays an important role in regulating chromosome structure and modulating gene expression. The full-length JIL-1 protein is composed of four domains including a N-terminal domain (NTD), two kinase domains (KDI and KDII), and a unique C-terminal domain (CTD). In order to study the biological importance of these individual domains, a domain analysis research approach was taken and different functions ...


Peasant Communities, The First Link Of The Commodity Chain Of Vicuña Fiber, Liliana L. Lay Lisung Jan 2008

Peasant Communities, The First Link Of The Commodity Chain Of Vicuña Fiber, Liliana L. Lay Lisung

Retrospective Theses and Dissertations

Vicuna fiber has a high value in the textile and fashion industry and is seen on the runways of the most selective and luxurious clothing designers in Europe. However, the vicuna fiber process and commodity chain are little known. This thesis presents the commodity chain of vicuna fiber and the positive and negative impacts that vicuna fiber commercialization generates in Peruvian peasant communities. The research, based on in-depth interviews and document analysis, studies the development of this buyer-driven chain, the social actors' roles, and the policies and legislation implemented to preserve vicuna species. In response to consumption demands, the marketing ...


Interactive Graphics, Graphical User Interfaces And Software Interfaces For The Analysis Of Biological Experimental Data And Networks, Michael Lawrence Jan 2008

Interactive Graphics, Graphical User Interfaces And Software Interfaces For The Analysis Of Biological Experimental Data And Networks, Michael Lawrence

Retrospective Theses and Dissertations

Biologists need to analyze and comprehend increasingly large and more complex multivariate experimental data. Biological experiments often produce multiple data sets, each describing one aspect of the system, such as the transcriptome recorded by a microarray or metabolome recorded using gas chromatography mass spectrometry (GC-MS). A biochemical network model provides a conceptual system-level framework for integrating data from different sources.;Effective use of graphics enhances the comprehension of data, and interactive graphics permit the analyst to actively explore data, check its integrity, satiate curiosities and reveal the unexpected. Interactive graphics have not been widely applied as a means for understanding ...


Studies Of Intermediates And Regulation In Snare-Mediated Membrane Fusion, Xiaobing Lu Jan 2008

Studies Of Intermediates And Regulation In Snare-Mediated Membrane Fusion, Xiaobing Lu

Retrospective Theses and Dissertations

At the synapse, neurotransmitters are released via Ca2+-triggered exocytotic fusion of synaptic vesicles with the presynaptic plasma membrane. The whole process is controlled by various proteins. SNAREs have been recognized as the key components that drive membrane fusion. In addition, many other proteins, such as Munc18/nSec1, Mun13, synaptotagmin, complexin, etc. are characterized to regulate synaptic transmission temporally and spatially.;The in vitro bulk fluorescence assay was applied to examine the kinetics of membrane fusion of liposomes mediated by recombinant neuronal SNAREs and led to the demonstration of hemifusion as an intermediate in the pathway. In order to monitor ...


Identification, Evaluation And Quantification Of Vocs As Biosecure Markers Of Swine Carcass Degradation, Neslihan Akdeniz Jan 2008

Identification, Evaluation And Quantification Of Vocs As Biosecure Markers Of Swine Carcass Degradation, Neslihan Akdeniz

Retrospective Theses and Dissertations

Swine carcasses were composted using passively-aerated composting system designed by the Canadian Food Inspection Agency during the 2004 Avian influenza outbreak in British Columbia. In this system, swine carcasses were fully covered by plastic sheets due to biosecurity concerns and visual inspection of the swine carcasses was impossible. Monitoring volatile organic compounds (VOCs) released from carcasses was a promising approach to assess progress and completion of the carcass degradation. In this study, VOCs were sampled using solid phase microextraction (SPME). Samples were analyzed using multidimensional gas chromatography-mass spectrometry (MDGC-MS) (a) to develop a comprehensive chemical library of volatile organic compounds ...


Monitoring Vegetative Treatment System Performance For Open Beef Feedlot Runoff Control, Ishadeep Khanijo Jan 2008

Monitoring Vegetative Treatment System Performance For Open Beef Feedlot Runoff Control, Ishadeep Khanijo

Retrospective Theses and Dissertations

Vegetative treatment systems (VTS) are an alterative technology designed to control runoff from open beef feedlots. A VTS consists of a solids settling basin (SSB) followed by a vegetative treatment area (VTA) or a combination of vegetative infiltration basin (VIB) and a VTA. Four sites were monitored in 2006 and 2007 to evaluate the performance of the VTSs in Iowa. In 2006, the percent runoff control at Central IA 1 & 2 and Northwest IA 1 & 2 was measured as 99, 74, 96, and 98 respectively. In 2007, the SSB outlets were actively managed and the percent runoff control at Central ...


Phylogenetic Placement And Population Genetic Analysis Of The Endangered Winged Mapleleaf, Quadrula Fragosa, Amanda Heather Hemmingsen Jan 2008

Phylogenetic Placement And Population Genetic Analysis Of The Endangered Winged Mapleleaf, Quadrula Fragosa, Amanda Heather Hemmingsen

Retrospective Theses and Dissertations

The endangered winged mapleleaf, Quadrula fragosa once occurred in the Mississippi, Tennessee, Ohio, and Cumberland River basins in the United States. While the range of this species was thought to have been reduced to a single population in the St. Croix River (Minnesota/Wisconsin), individuals morphologically similar to Q. fragosa were recently recorded in Missouri, Arkansas, and Oklahoma. We employed a phylogenetic analysis of mitochondrial ND1 gene sequences. Our results indicate that Q. fragosa is a separate species and that the southern populations are genetically Q. fragosa. In addition, we developed and utilized 12 microsatellite loci to quantify genetic variation ...


Relationship Of Centrally-Located Body Fat To Appetitive Hormones In Healthy Postmenopausal Women, Laura Marie Ritland Jan 2008

Relationship Of Centrally-Located Body Fat To Appetitive Hormones In Healthy Postmenopausal Women, Laura Marie Ritland

Retrospective Theses and Dissertations

Objective. Body composition and energy homeostasis are thought to affect the appetitive hormones: adiponectin, leptin, insulin, and ghrelin. This study examined whether centrally-located fat and/or overall adiposity were related to these appetitive hormones in healthy postmenopausal women.;Design. Overall and regional body composition was assessed by dual-energy X-ray absorptiometry in relation to plasma adiponectin, serum leptin, serum insulin, and plasma ghrelin in 242 postmenopausal women.;Results. Regression analyses revealed that the androidal-to-gynoidal fat mass ratio (18.0%), age (3.2%), and white blood cell count (1.8%) accounted for 28% of the variability in adiponectin (F=22.2; P ...


Assembly And Annotation Tools For Analysis Of Large Contiguous Regions Of The Maize Genome, Brent Anson Kronmiller Jan 2008

Assembly And Annotation Tools For Analysis Of Large Contiguous Regions Of The Maize Genome, Brent Anson Kronmiller

Retrospective Theses and Dissertations

Sequencing projects continue to tackle larger and more challenging genomes. Many of the grass genomes have important agriculture and economic impacts. The maize genome is now underway, and others important as foods and biofuels will be sequenced in the near future. The grass genomes are very large and therefore computationally complex to assemble and annotate. Long terminal repeat retrotransposons make up significant portions of many of the longer grass genomes. Their repeat sequences across the genome, their terminal repeats, and their nested cluster configuration make assembly of sequence clones challenging and identification of gene regions difficult. Tools are needed to ...


Mesoporous Silica Nanomaterials And Magnetic Nanoparticles Based Stimuli-Responsive Controlled-Release Delivery Systems, Supratim Giri Jan 2008

Mesoporous Silica Nanomaterials And Magnetic Nanoparticles Based Stimuli-Responsive Controlled-Release Delivery Systems, Supratim Giri

Retrospective Theses and Dissertations

The research presented and discussed within this dissertation involves the development of mesoporous silica nanomaterials and magnetic nanoparticles based stimuli-responsive controlled-release delivery systems.;A superparamagnetic iron oxide nanoparticle-capped, MCM-41 type mesoporous silica nanorod-based controlled-release delivery system (Magnet-MSN) was synthesized. The stimuli-responsive release profiles of fluorescein-loaded Magnet-MSN delivery systems in the presence of external magnetic field was studied by using cell-produced antioxidants as triggers for releasing fluorescein molecules. The intracellular delivery efficiency of the Magnet-MSN system with human cervical cancer cells (HeLa) in vitro was demonstrated involving fluorescein molecules as model drug.;To take the advantage of the intracellular delivery capability ...


Relatedness Of Haemophilus Parasuis Strains And Their Proteins' Possible Roles As Virulence Factors, Emilie Susanna Noel Zehr Jan 2008

Relatedness Of Haemophilus Parasuis Strains And Their Proteins' Possible Roles As Virulence Factors, Emilie Susanna Noel Zehr

Retrospective Theses and Dissertations

Haemophilus parasuis, the causative agent of Glasser's disease, is considered to be a remerging pathogen of swine in high-health status herds. Several molecular typing methods have been suggested as alternatives to serotyping, which failed to identify up to 30% of field isolates. This study compared random amplification of polymorphic DNA (RAPD) profiles and protein profiles of H. parasuis reference strains and field isolates as methods for identifying and grouping virulent and avirulent isolates. DNA and protein profiles of 15 reference strains and 31 field isolates of H. parasuis, analyzed with two computer-based similarity analyses, revealed unique and reproducible DNA ...


Interaction Of Fungicide Seed Treatments And The Fusarium-Maize (Zea Mays L.) Pathosystem, Carlos Rodriguez-Brljevich Jan 2008

Interaction Of Fungicide Seed Treatments And The Fusarium-Maize (Zea Mays L.) Pathosystem, Carlos Rodriguez-Brljevich

Retrospective Theses and Dissertations

Maize stand losses and seedling blights due to Fusarium spp. continue to be one of the most economically important diseases in maize production. Consequently, all maize seed is treated with a mixture of fungicides that improves seedling emergence and yield. Data on the interaction between Fusarium spp. and seed treatment fungicides are limited. The effectiveness of seven fungicide active ingredients against seed-borne F. verticillioides was assessed under controlled environmental conditions. In addition the effects of fungicide seed treatments on seedling blight development and early season growth and physiology of maize were evaluated in the field at two locations in Iowa ...


Proteins Affecting Rod Photoreceptor Differentiation In The Murine Retina: A Proteomics Approach With Emphasis On Mtor, Alison Elizabeth Barnhill Jan 2008

Proteins Affecting Rod Photoreceptor Differentiation In The Murine Retina: A Proteomics Approach With Emphasis On Mtor, Alison Elizabeth Barnhill

Retrospective Theses and Dissertations

Retinal diseases involving degeneration of photoreceptors are an increasing cause of blindness in this country, particularly among the aging population. A solid understanding of retinal development is central to combating photoreceptor degeneration on several fronts. Defining developmental processes may have therapeutic relevance in 'rehabilitating' photoreceptor cells that can be rescued from degenerative processes by the application of exogenous trophic or survival factors. Further, advances in stem cell research may someday make replacement of photoreceptors a feasible therapy for the treatment of retinal degeneration. In this regard, it will be crucial that we have a clear understanding of the developing retinal ...


Quantitative Studies On Airborne Transmission Of Porcine Reproductive And Respiratory Syndrome Virus, Joseph Ralph Hermann Jan 2008

Quantitative Studies On Airborne Transmission Of Porcine Reproductive And Respiratory Syndrome Virus, Joseph Ralph Hermann

Retrospective Theses and Dissertations

Porcine reproductive and respiratory syndrome virus (PRRSV) is an enveloped RNA virus in the family Arteriviridae within the order Nidovirales (Cavanagh, 1997).;The objective of the first study was to optimize sampling parameters for increased recovery and detection of airborne PRRSV and swine influenza virus (SIV). Collection media containing antifoams, activated carbons, protectants, and ethylene glycol were evaluated for direct effects on factors impacting the detection of PRRSV and SIV, including virus infectivity, viability of continuous cell lines used for the isolation of these viruses, and performance of reverse-transcriptase polymerase chain reaction (RT-PCR) assays. The results showed that specific compounds ...


The Effects Of Mid-Air Adjustments On Knee Joint Loading When Landing From A Jump, Guan Qiang Tan Jan 2008

The Effects Of Mid-Air Adjustments On Knee Joint Loading When Landing From A Jump, Guan Qiang Tan

Retrospective Theses and Dissertations

Introduction. One of the most common injuries involving the knee joint is the Anterior Cruciate Ligament (ACL) tear. Female basketball and soccer players have about 3 times higher risk of ACL injury versus male athletes (Prodromos et al., 2007). Female athletes alter their motion pattern during the landing phase differently than male athletes. That is one of the potential reasons why females have a higher risk of ACL injury during sports (Chappell et al., 2002). Possible mechanisms of ACL injury are the deceleration of the knee in an extended position (Boden et al., 2000), shear forces applied to the leg ...


Swine Wastewater Treatment By The Static Granular Bed Reactor, Seung Joo Lim Jan 2008

Swine Wastewater Treatment By The Static Granular Bed Reactor, Seung Joo Lim

Retrospective Theses and Dissertations

Swine wastewater was successfully treated by the SGBR. Two types of swine wastewater samples were used, and the performance of the SGBR was excellent. COD removal efficiency of sample 1 was 84.7∼94.5%, while that of sample 2 was 58.4∼76.6%. The SGBR acted not only as a bioreactor but also as a filter system. The performance of suspended solids removal was excellent irrespective of the OLR. Additionally, the COD removal efficiency in the effluent after backwashing was not a function of the recovery time but that of the OLR.;The SGBR model was developed with ...


Diversity, Productivity, And Stability In Perennial Polycultures Used For Grain, Forage, And Biomass Production, Valentín Daniel Picasso Risso Jan 2008

Diversity, Productivity, And Stability In Perennial Polycultures Used For Grain, Forage, And Biomass Production, Valentín Daniel Picasso Risso

Retrospective Theses and Dissertations

The objective of this dissertation was to determine to what extent plant species diversity affects biomass and seed productivity, weed invasion, and stability in perennial herbaceous polycultures across three years, two harvest management regimes, and two locations in central Iowa, USA. Average biomass productivity consistently increased in polycultures with increasing species richness across all environment-years. In most situations, polycultures were more productive than the average of monocultures, but not more productive than the best adapted species in monoculture for each environment. Polyculture overyielding was due to complementarity among species in the community rather than to selection effects of individual species ...


Genetic Diversity In Cultivated And Wild Hordeum Species, Lucía Gutiérrez Jan 2008

Genetic Diversity In Cultivated And Wild Hordeum Species, Lucía Gutiérrez

Retrospective Theses and Dissertations

Phenotypic selection can be tested by comparing the inter-population variation in quantitative traits (QST) against inter-population variation in neutral molecular markers (FST). A trait is considered under divergent selection when QST > FST, under stabilizing selection when QST < FST, and selectively neutral when QST = FST. This approach assumes the form of selection to be consistent across populations and can fail to detect selection mosaics in which this consistency is lacking. The overall objectives of this work are to improve the methodology for comparing QST and FST, and to study the relationship between QST and FST in cultivated and wild barley. First, we develop a methodology to detect situations in which the form of selection is heterogenous. The methodology simulates pair-wise QST under neutrality and focuses on the distribution of QST and FST. Our results indicate that studies employing traditional QST and FST methods are insensitive to mixtures of disruptive and stabilizing selection and that more powerful inference concerning the form of selection may be gained via the methods introduced here. Second, we use overall and pair-wise estimates to study the evolutionary history of quantitative traits in wild barley. We evaluate 14 traits and 56 SSR markers in 280 genotypes from 23 populations of wild barley from the Fertile Crescent. We find that a combination of overall and pair-wise comparisons is better suited than the former alone to understand the evolutionary processes that shape populations. Third, we propose the use of QST and F ST studies in cultivated barley. We use 66 polymorphic SSR and 20 quantitative traits in 353 genotypes of barley from 23 breeding programs distributed worldwide. By simultaneously estimating population structure at morphological traits and neutral molecular markers, we identify compatible breeding programs for germplasm exchange, and breeding programs with unique characteristics worth preserving. However, caution is advised in the use of this methodology for fitness-related traits, traits with important GxE, and germplasm with strong artificially-imposed structure especially in an artificial selection context as in breeding programs. In summary, we develop a methodology that is effective for detecting selection mosaics and we provided ample evidence of the occurrence of this phenomenon in both wild and cultivated barley.


Mechanisms Of Bes1-Regulated Gene Expression Downstream Of Brassinosteroid Signaling In Arabidopsis Thaliana, Xiaofei Yu Jan 2008

Mechanisms Of Bes1-Regulated Gene Expression Downstream Of Brassinosteroid Signaling In Arabidopsis Thaliana, Xiaofei Yu

Retrospective Theses and Dissertations

Brassinosteroids (BRs), the plant steroid hormones, play an important role in mediating plant responses to developmental and environmental cues. BRs signal through a membrane receptor BRI1 and a GSK3 kinase BIN2 to control the activity of BES1/BZR1 family transcription factors. To understand how BES1 regulates gene expression, I looked into both trans-acting protein factors and cis-acting DNA elements that affect BES1 functions, by yeast genetic screen and chromatin immunoprecipitation coupled with DNA microarray (ChIP-chip), respectively. We identified 1609 BES1 direct target genes and discovered conserved DNA motifs in BES1 binding regions. We also showed that BES1 target genes were ...


Comparison Of Carcass Composition, Performance, And Tissue Deposition Rates Among Breeds Of Swine, Bryce David Martin Jan 2008

Comparison Of Carcass Composition, Performance, And Tissue Deposition Rates Among Breeds Of Swine, Bryce David Martin

Retrospective Theses and Dissertations

A study was conducted to evaluate differences in performance, carcass traits, and tissue deposition rates among breeds of swine entered in the 2003 National Barrow Show Progeny Test. The test consisted of 362 barrow and gilt progeny from sires within each of the 8 breeds evaluated. Breeds tested were Berkshire (n = 158), Duroc (n = 76), Chester White (n = 53), Yorkshire (n= 31), Spotted (n = 15), Landrace (n = 15), Poland (n = 8), and Hampshire (n = 6). Due to small sample size, the Spotted, Landrace, Poland, and Hampshire breeds were combined in an All Other Breeds (AOB) category. Progeny were weighed and ...


Evolutionary Variance Of Gene Network Model Via Simulated Annealing, Kyoungmin Roh Jan 2008

Evolutionary Variance Of Gene Network Model Via Simulated Annealing, Kyoungmin Roh

Retrospective Theses and Dissertations

The traditional approach of molecular biology research was on examining and collecting data on a single gene or a single reaction. However, recently, there has been much interest on the dynamics of gene regulatory networks (Klipp et al., 2005). We applied mathematical approach for modeling of gene network. The models depict the reaction kinetics of the constituent parts and the functions are ultimately made from basic principle of simple expressions derived from Michaelis-Menten enzymatic kinetics, and the functional forms are usually chosen as Hill functions that serve as an approximation for the real molecular dynamics (Klipp et al., 2005). These ...


Force And Moment Analysis Of Stacked Counter Rotating Eccentric Mass Tree Shaker Energy-Wheel System, Lloyd Dale Snell Jan 2008

Force And Moment Analysis Of Stacked Counter Rotating Eccentric Mass Tree Shaker Energy-Wheel System, Lloyd Dale Snell

Retrospective Theses and Dissertations

The tree shaker is a high throughput hydro-mechanical systems used in nut and fruit harvest. Many commercial tree shakers use stacked counter rotating eccentric mass energy-wheels to dislodge the crop from the tree by attaching and shaking the trunk. Tree shakers are known to cause tree trunk damage by approach impact, barking, and bruising of the tree trunk. Tree trunk damage, catastrophic or accumulative, could account for a 4% lifetime production loss, 1408 kg/hectare.;The energy-wheels are commonly known to create planer pulse forces. The pulse is created by the rotation of eccentric mass about a fixed common shaft ...


Alternative Approaches For Sharing Machinery, Labor, And Other Resources Among Small- And Medium-Sized Agricultural Producers, Greg Colson Jan 2008

Alternative Approaches For Sharing Machinery, Labor, And Other Resources Among Small- And Medium-Sized Agricultural Producers, Greg Colson

Retrospective Theses and Dissertations

As the U.S. agriculture industry continues to become increasingly concentrated, the viability of small- and medium-sized farms faced with diminishing profit margins per unit of output hinges in part on their ability to expand operations. In this study, the solution to this problem of taking advantage of economies of scale through farm-level resource sharing arrangements is considered. Through a two phase data collection procedure, Midwestern farmer groups engaged in resource sharing arrangements were identified and investigated through a case study approach. Evidence from the case studies suggest that sharing of equipment and labor can yield not only financial benefits ...


Irradiance, Total Nitrogen, And Nitrate-N: Ammonium-N Ratio Requirements For Optimal Edible Biomass Production Of Basil, Angela Renee Beaman Jan 2008

Irradiance, Total Nitrogen, And Nitrate-N: Ammonium-N Ratio Requirements For Optimal Edible Biomass Production Of Basil, Angela Renee Beaman

Retrospective Theses and Dissertations

Our objective was to determine the optimal irradiance, total N concentration, and NO3--N:NH4+-N ratio for greatest edible biomass production of three cultivars of basil (Basilicum ocimum L.) in a controlled-environment production system. Preliminary experiments showed basil required a dark period, but the duration of the dark period was not resolved. Based on our results, canopy-level irradiance should not exceed 500 mumol/m2/s to conserve energy while enabling the greatest edible biomass production of basil in a controlled-environment production system. Optimal edible biomass production occurred at 100 to 250 mg N/L at a ratio of 50:50 ...