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Retrospective Theses and Dissertations

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Full-Text Articles in Life Sciences

Essays On Fall Fertilizer Application, Mira Nurmakhanova Jan 2008

Essays On Fall Fertilizer Application, Mira Nurmakhanova

Retrospective Theses and Dissertations

Increased use of nitrogen fertilizer in agricultural production has contributed to increased food production but also contributed to elevated concentration levels of nitrates in groundwater and surface water. High concentration levels of nitrates in drinking water supplied from groundwater and surface water have become a public concern because of their risks to human health.;One way to reduce nitrogen losses is to develop and apply technologies that enable farmers to more accurately match the amount and timing of fertilizer application to crop growth needs. It is best to apply nitrogen as close as possible to when crop needs it most ...


Laser Desorption/Ionization Mass Spectrometry For Direct Profiling And Imaging Of Small Molecules From Raw Biological Materials, Sangwon Cha Jan 2008

Laser Desorption/Ionization Mass Spectrometry For Direct Profiling And Imaging Of Small Molecules From Raw Biological Materials, Sangwon Cha

Retrospective Theses and Dissertations

Matrix-assisted laser desorption/ionization(MALDI) mass spectrometry(MS) has been widely used for analysis of biological molecules, especially macromolecules such as proteins. However, MALDI MS has a problem in small molecule (less than 1 kDa) analysis because of the signal saturation by organic matrixes in the low mass region. In imaging MS (IMS), inhomogeneous surface formation due to the co-crystallization process by organic MALDI matrixes limits the spatial resolution of the mass spectral image. Therefore, to make laser desorption/ionization (LDI) MS more suitable for mass spectral profiling and imaging of small molecules directly from raw biological tissues, LDI MS ...


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 ...


The Structure And Mechanism Of Saicar Synthetase, Nathaniel Daum Ginder Jan 2008

The Structure And Mechanism Of Saicar Synthetase, Nathaniel Daum Ginder

Retrospective Theses and Dissertations

SAICAR synthetase catalyzes the eighth step in bacterial de novo purine nucleotide biosynthesis: ATP + L-aspartate + CAIR → ADP + Pi + SAICAR Enzymes involved in nucleotide synthesis are common targets for chemotherapeutic and antimicrobial drugs. They work by reducing the rate of growth of rapidly proliferating cells, thus preventing tumor growth and microbial fecundity. L-Alanosine, an L-aspartate analogue that acts as a substrate for SAICAR synthetase, is a natural product with antiviral and antitumor activities. The product of the reaction is a potent inhibitor of adenylosuccinate synthetase and adenylosuccinate lyase and is responsible for L-alanosine toxicity. L-Alanosine may be effective as a chemotherapeutic ...


Predicting Loads On Ground Engaging Tillage Tools Using Computational Fluid Dynamics, Mark Eugene Barker Jan 2008

Predicting Loads On Ground Engaging Tillage Tools Using Computational Fluid Dynamics, Mark Eugene Barker

Retrospective Theses and Dissertations

A new method of evaluating tillage tools using computational fluid dynamics is proposed. Steady-state CFD only and transient two-way fluid-structure interaction simulations were run to predict draft and vertical forces on a spring-reset field cultivator standard. Using CFD the soil was treated as a visco-plastic fluid using the Bingham-plastic material model. Lab tests were run using a rigid flat steel bar and a production field cultivator standard with 178 and 254 mm sweeps for comparison. The results indicate that the method can be used to reasonably predict the draft force to within three standard deviations of the average measured draft ...


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 ...


An Integrated Approach To Investigating The Reintroduction Of Flax Production In Iowa, Sarah Louise Carlson Jan 2008

An Integrated Approach To Investigating The Reintroduction Of Flax Production In Iowa, Sarah Louise Carlson

Retrospective Theses and Dissertations

The objectives of this research are a biological and sociological approach. These results will provide upper Midwestern, specifically Iowa, organic farmers with current, agronomic production guidelines from research conducted on-farm and on experiment stations, and to analyze the capability of these farmers to incorporate this alternative crop into their crop rotations. The effect of planting date, cultivar selection, planting rate, legume establishment, weed management strategies categorized as mechanical, chemical and biological: flax grain yield, straw biomass yield, total oil content, fatty acid profile, and underseeding and weed biomass production are analyzed. Additionally, straw quality characteristics were assessed.


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 ...


A Negative Regulator Of Ribosomal Rna Processing Specifies R-Gene-Independent Cell Death In Barley - Powdery Mildew Interactions, Liu Xi Jan 2008

A Negative Regulator Of Ribosomal Rna Processing Specifies R-Gene-Independent Cell Death In Barley - Powdery Mildew Interactions, Liu Xi

Retrospective Theses and Dissertations

Programmed Cell Death (PCD) plays a pivotal role in plant development and defense. Pathogen dependent cell-death mutants were used to investigate the complex regulatory pathways between PCD and R-gene mediated resistance. Time-course expression profiles of Blumeria graminis f. sp. hordei (Bgh) challenged C.I. 16151 (harboring the Mla6 powdery mildew resistance allele) and its fast-neutron-derived "Bgh-induced tip cell death1" mutant, bcd1, were compared using the 22K Barley1 GeneChip. Contrasts were made to identify genes associated with the cell death phenotype as opposed to R-gene mediated resistance. One hundred eighty-two genes were found in the intersection of these contrasts at a ...


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 ...


Effects Of Substrate And Co-Culture On Neural Progenitor Cell Differentiation, Erin Boote Jones Jan 2008

Effects Of Substrate And Co-Culture On Neural Progenitor Cell Differentiation, Erin Boote Jones

Retrospective Theses and Dissertations

For stem and progenitor cells to become clinically useful, the factors that influence their differentiation must be better understood. The interaction between progenitor cells and their environment is thought to be one of the main influences on differentiation. This thesis examines the effects of media conditioned by primary astrocytes and extracellular matrix protein surface coatings on the differentiation of neural progenitor cells.


The Locations And Signaling Of H-Ras On Endosomes And Plasma Membrane, Xing Wang Jan 2008

The Locations And Signaling Of H-Ras On Endosomes And Plasma Membrane, Xing Wang

Retrospective Theses and Dissertations

No abstract provided.


The Land, It's Everything: Women Farmland Owners And The Institution Of Agricultural Conservation In The U.S. Midwest, Jean Crim Eells Jan 2008

The Land, It's Everything: Women Farmland Owners And The Institution Of Agricultural Conservation In The U.S. Midwest, Jean Crim Eells

Retrospective Theses and Dissertations

This institutional ethnography was undertaken to address the problematic that far fewer women than men participate in the institution of agricultural conservation despite the fact that about the same numbers of men and women own roughly equal amounts of agricultural land in the U.S. Midwest. The institution of agricultural conservation---governmental agencies and private non-profit organizations---provides conservation services such as technical assistance and funding to clients, private farmland owners, who implement conservation practices on their lands.;As a qualitative research methodology, institutional ethnography (IE) is a way to examine otherwise intractable or elusive problems that exist on an institutional level ...


Hypothesis Building Using The Animal Trait Ontology, Laron Maurice Hughes Jan 2008

Hypothesis Building Using The Animal Trait Ontology, Laron Maurice Hughes

Retrospective Theses and Dissertations

With the advent of sequencing projects in model organisms, humans, and domesticated livestock species, the need for storage, retrieval, and analysis of genomics information for these animals has become important. The Animal Trait Ontology (ATO) is an ontology that has been created to store the relationships between farm animal traits for several domesticated farm animals. The Collaborative Ontology Building (COB) editor was used to create and edit the ATO. An online ontology browser has been developed to search and browse the ontology and to view the relationships between the terms. Some of the traits in the ontology are linked to ...


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 ...


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 ...


Agronomic Performance, Seed Characteristics, And Stability Of Soybean Lines Containing Mid Oleate Content And Molecular Analysis For Diversity In The Fad2-1b Gene, Curtis Wilmer Scherder Jan 2008

Agronomic Performance, Seed Characteristics, And Stability Of Soybean Lines Containing Mid Oleate Content And Molecular Analysis For Diversity In The Fad2-1b Gene, Curtis Wilmer Scherder

Retrospective Theses and Dissertations

Soybean [Glycine max (L.) Merr.] lines with increased levels of oleate content may be useful for the food industry. Iowa State University has used the mutant soybean line, M23, developed by Saga University in Japan, to develop lines that contain mid-oleate content combined with 10 g kg -1 linolenate (MO/LLN), low saturated fatty acids (MO/LS), and both low saturated fatty acids and 10 g kg-1 linolenate (MO/LS/LLN). The first objective of the research was to determine the stability of oleate content across four Iowa environments and one Missouri environment in two years for the three types ...


The Evaluation Of Maize Genotypes For Potential Use In Cellulosic Ethanol Production, Krystal Marie Kirkpatrick Jan 2008

The Evaluation Of Maize Genotypes For Potential Use In Cellulosic Ethanol Production, Krystal Marie Kirkpatrick

Retrospective Theses and Dissertations

Corn stover represents a potential lignocellulosic feedstock that may benefit the emerging cellulosic ethanol industry. This study was conducted to determine dry matter yield and quality characteristics of maize stover, cob, and husk plant fractions, and to make predictions of potential ethanol yields. Detergent fiber predictions were made for each plant fraction using near infrared reflectance spectroscopy (NIRS). Predicted values were used to determine ethanol potential using a modified version of the National Renewable Energy Lab (NREL) theoretical ethanol yield calculator. Although significant, not as much variation was present among genotypes and plant fractions for chemical composition as for dry ...


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 ...


Maize (Zea Mays L.) Kernel Development, Suitability For Dry-Grind Ethanol Production, And Susceptibility To Aflatoxin Accumulation In Relation To Late-Season Water Stress, Jason Wade Haegele Jan 2008

Maize (Zea Mays L.) Kernel Development, Suitability For Dry-Grind Ethanol Production, And Susceptibility To Aflatoxin Accumulation In Relation To Late-Season Water Stress, Jason Wade Haegele

Retrospective Theses and Dissertations

Worldwide, water stress during vegetative and reproductive development of cereal species is a primary constraint to crop yield. In maize ( Zea mays L.), environmental stresses such as high temperature and drought affect yield by reducing the number and mean dry weight of harvested seeds per unit area. Total grain yield is of great economic concern, and increasing yield under optimal and stress conditions has historically received the most attention by public and private breeding programs. But environmental effects on grain quality is of equal importance as maize production becomes more focused on end-user traits specifically for utilization in markets such ...


The Effects Of Farmer Attitudes And Farm Management Practices On Soil Quality: A Study In Cherokee County, Iowa, Amber D. Anderson Mba Jan 2008

The Effects Of Farmer Attitudes And Farm Management Practices On Soil Quality: A Study In Cherokee County, Iowa, Amber D. Anderson Mba

Retrospective Theses and Dissertations

This study seeks to relate farmer attitudes, perceptions, and management characteristics to field soil quality and laboratory fertility indicators. Farmer interviews were conducted to document recent practices on the farm as well as farmer attitudes about farming. To obtain soil quality measures, both the Natural Resource Conservation Service's field soil quality kit and laboratory tests were employed. Sites from the eastern half of Cherokee County, Iowa, were selected.;Key considerations of this study included farmer practices of renting versus owning land and organic or synthetic nitrogen application. Additional farmer data, including attitudes about farming, are used in this analysis ...


Purchasing Practices, Barriers, And Industry Support In Child Nutrition Programs Needed To Meet Wellness Policy Requirements, Tami Jo Cline Jan 2008

Purchasing Practices, Barriers, And Industry Support In Child Nutrition Programs Needed To Meet Wellness Policy Requirements, Tami Jo Cline

Retrospective Theses and Dissertations

Beginning with the 2006-2007 school year, schools were required by the U.S. Department of Agriculture to implement local wellness policies. Because this area of study is relatively new, a limited number of readings were found in the literature related to implementation of such policies, as well as the content of policies implemented thus far. The purpose of this study was to use focus group and survey data to identify the purchasing practices used by the largest 100 school districts and industry's perception of the purchasing practices used in schools.;Specific research objectives included determining if the largest 100 ...


An Assessment Of Performance Measures In Child Nutrition Programs, Elizabeth Northway Hanna Jan 2008

An Assessment Of Performance Measures In Child Nutrition Programs, Elizabeth Northway Hanna

Retrospective Theses and Dissertations

School Child Nutrition Program (CNP) directors are expected to operate efficient, productive, and effective meals programs (Boehrer, 1993; Decker, et al. 1992; USDA, 2008). A variety of performance measures can be used to assess CNPs' operational effectiveness. The purposes of this research were to investigate management and financial attributes perceived by foodservice directors of medium-size public school districts in the United States to impact performance measures for CNPs and investigate whether widely used standards for these performance measures, based on previous research, were relevant due to a variety of changes that had occurred in CNPs.;Two electronic questionnaires were sent ...


The Study Of The Impact Of The M.S. In Agronomy Distance Education Program On Student Careers, Jesse Duane Drew Jan 2008

The Study Of The Impact Of The M.S. In Agronomy Distance Education Program On Student Careers, Jesse Duane Drew

Retrospective Theses and Dissertations

The purpose of this research study was to examine whether the Master of Science in Agronomy Distance Education Program at Iowa State University has had an impact on students' career mobility and economic status. Lifelong learning opportunities for agricultural professionals, like a majority of other field professional are growing exponentially. During the 2004 fall semester, 53 participants in the Master of Science in Agronomy Distance Education Program were given the Distance Education Impact Assessment Survey (DEIAS). Additional knowledge and training for adult students is essential for career advancement, and this research project intends to demonstrate how a Master of Science ...


Comparison Of Air-Displacement Plethysmography And Hydrodensitometry In High School Football Linemen, Timothy Egan Moran Jan 2008

Comparison Of Air-Displacement Plethysmography And Hydrodensitometry In High School Football Linemen, Timothy Egan Moran

Retrospective Theses and Dissertations

Recently, there has been concern about obesity and its co-morbidities among football linemen from the youth to professional level. The purpose of this study was two-fold: (1) to examine the association between body mass index (BMI) and percentage fat determined by air-displacement plethysmography (ADP) and hydrodensitometry (HW) in high school football linemen and (2) to compare ADP with HW in high school football linemen to determine the feasibility and accuracy of ADP compared with HW in this group. Thirty-one high school football linemen were recruited from local high schools and were measured for height, body mass, and percentage fat estimated ...


Analysis Of A Ddgs Air-Drying System With Heat Recovery, Christopher Brady Hoeck Jan 2008

Analysis Of A Ddgs Air-Drying System With Heat Recovery, Christopher Brady Hoeck

Retrospective Theses and Dissertations

Dry Distiller Grains with Soluble (DDGS) are a co-product of the conversion from corn into Ethanol fuel. Several applications depend on the ability of a drying process to remove moisture from a product, such as DDGS, in an effective and economical manner. Common drying methods use air to facilitate product drying as it proficiently absorbs the unwanted moisture, creating a moist-air mixture that captures both the latent and sensible heat released from the product. The most economical approach to an Air Drying System integrates a heat recovery system that transfers the heat removed by the moist-air mixture during drying back ...


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 ...


Phylogenetic Relationships Among The Temperate Bamboos (Poaceae: Bambusoideae) With An Emphasis On Arundinaria And Allies, Jimmy K. Triplett Jan 2008

Phylogenetic Relationships Among The Temperate Bamboos (Poaceae: Bambusoideae) With An Emphasis On Arundinaria And Allies, Jimmy K. Triplett

Retrospective Theses and Dissertations

The temperate clade is a diverse but poorly understood major lineage of woody bamboos (Poaceae: Bambusoideae: Bambuseae). Ongoing work is needed to reconstruct evolutionary relationships and establish nomenclatural stability for this difficult but ecologically and economically important group. We present the first robust multilocus plastid phylogeny for the temperate bamboos, assess relationships among key genera with an emphasis on Arundinaria and its allies, and discuss evolutionary phenomena potentially responsible for the taxonomic complexity of this group. Utilizing a total of twelve cp DNA regions (1 coding, 10 intergenic spacers, 1 intron), the temperate bamboos were resolved to include six major ...


Physiology And Pharmacology Of Flatworm Muscle, Ekaterina B. Novozhilova Jan 2008

Physiology And Pharmacology Of Flatworm Muscle, Ekaterina B. Novozhilova

Retrospective Theses and Dissertations

Pharmacological characterization of voltage-operated Ca2+ channels (VOCCs), in both free-living and parasitic flatworms, has been difficult since the currents carried by these channels are small in amplitude and run down quickly. While the presence of VOCCs in the parasite Schistosoma mansoni has been evident from molecular data, they have escaped pharmacological characterization. In this study, we have been able to consistently record inward currents carried by VOCCs in isolated S. mansoni muscle fibers, using whole cell configuration of the patch-clamp technique in voltage-clamp mode. Inward voltage-activated current was recorded, under conditions that suppressed outward K+ conductance, by the replacement of ...


Porcine Reproductive And Respiratory Syndrome Virus: Understanding And Managing Persistent Infection, Ramón Miguel Molina Barrios Jan 2008

Porcine Reproductive And Respiratory Syndrome Virus: Understanding And Managing Persistent Infection, Ramón Miguel Molina Barrios

Retrospective Theses and Dissertations

This experiment was designed as a longitudinal study in which pigs were followed for up to 202 days post inoculation (DPI). On day 0, 109 3-week-old pigs were intramuscularly inoculated with PRRSV strain VR-2332. Negative control pigs (n = 56) were sham inoculated with MEM by the intramuscular route. Thereafter, at approximately 2-week intervals, samples were collected from all animals and a subset of randomly selected animals was euthanized and tissues collected. The presence and amount of virus was assessed using qRT-PCR, standard virus isolation, and bioassay. Detection of PRRSV in serum by qRT-PCR showed that most pigs cleared the viremia ...