Browsing by Subject "transport"
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Item A spatial multigrid iterative method for two-dimensional discrete-ordinates transport problems(Texas A&M University, 2005-08-29) Lansrud, Brian DavidIterative solutions of the Boltzmann transport equation are computationally intensive. Spatial multigrid methods have led to efficient iterative algorithms for solving a variety of partial differential equations; thus, it is natural to explore their application to transport equations. Manteuffel et al. conducted such an exploration in one spatial dimension, using two-cell inversions as the relaxation or smoothing operation, and reported excellent results. In this dissertation we extensively test Manteuffel??s one-dimensional method and our modified versions thereof. We demonstrate that the performance of such spatial multigrid methods can degrade significantly given strong heterogeneities. We also extend Manteuffel??s basic approach to two-dimensional problems, employing four-cell inversions for the relaxation operation. We find that for uniform homogeneous problems the two-dimensional multigrid method is not as rapidly convergent as the one-dimensional method. For strongly heterogeneous problems the performance of the two-dimensional method is much like that of the one-dimensional method, which means it can be slow to converge. We conclude that this approach to spatial multigrid produces a method that converges rapidly for many problems but not for others. That is, this spatial multigrid method is not unconditionally rapidly convergent. However, our analysis of the distribution of eigenvalues of the iteration operators indicates that this spatial multigrid method may work very well as a preconditioner within a Krylov iteration algorithm, because its eigenvalues tend to be relatively well clustered. Further exploration of this promising result appears to be a fruitful area of further research.Item An experimental method to increase sediment supply to a salt marsh in subsidence dominated environments(Texas A&M University, 2007-09-17) Thomas, Robert C.This thesis examines the environmental conditions which led to the loss of 90% of the natural salt marsh in Galveston Island State Park since 1930 and analyzes one potential method to reduce future loss. Available data and recent studies suggest that the primary factor responsible for the historic loss was the lack of a sufficient supply of sediment to keep up with relative sea level rise. The average rate of sediment accretion for the period from 1963 to 2006 was measured to be 0.25 cm/year based on 137Cs and 239,240Pu nuclides. This rate is about 0.4 cm/year less than the relative sea level rise of approximately 0.65 cm/year during the same period. The marsh restoration project, constructed in 1999 at the Galveston Island State Park, focused on reduction of wave induced erosion and direct replacement of marsh substrate through terracing. The restoration project did not address the potential for marsh lost to submergence. As an alternative to geotubes or more permanent breakwater methods, a submerged sacrificial berm constructed around the marsh is a possible approach to address ongoing submergence. The sacrificial berm increases the available sediment supply by allowing partial transmission of waves to create a net transport of sediment into the marsh. In addition, the berm is designed to limit wave height in the marsh to reduce wave induced erosion. The proposed method involves iteratively adjusting the width and elevation of the berm top to maximize sediment transport from the berm into the marsh. A sediment transport model is developed to quantify the increased transport into the marsh, estimate a nourishment interval and qualitatively judge the expected berm evolution. The Galveston Island State Park marsh was used for demonstration purposes; however, the restoration concept and method of analysis is applicable to other marshes in Galveston Bay.Item Analytical modeling of contaminant transport and horizontal well hydraulics(Texas A&M University, 2004-09-30) Park, EungyuThis dissertation is composed of three parts of major contributions. In Chapter II, we discuss analytical study of contaminant transport from a finite source in a finite-thickness aquifer. This chapter provides analytical solutions of contaminant transport from one-, two-, and three-dimensional finite sources in a finite-thickness aquifer using Green's function method. A library of unpublished analytical solutions with different finite source geometry is provided. A graphically integrated software CTINT is developed to calculate the temporal integrations in the analytical solutions and obtain the final solutions of concentration. In Chapter III, we obtained solutions of groundwater flow to a finite-diameter horizontal well including wellbore storage and skin effect in a three-dimensionally anisotropic leaky aquifer. These solutions improve previous line source solutions by considering realistic well geometry and offer better description of drawdown near the horizontal well. These solutions are derived on the basis of the separation of the source and the geometric functions. The graphically integrated computer program FINHOW is written to generate type curves of groundwater flow to a finite-diameter horizontal well. The influence of the finite-diameter of the well, the wellbore storage, the skin effect, the leakage parameter, and the aquifer anisotropy is thoroughly analyzed. In Chapter IV, a general theory of groundwater flow to a fractured or non-fractured aquifer considering wellbore storage and skin effect is provided. Solutions for both leaky confined and water table aquifers are provided. The fracture model used in this study is the standard double-porosity model. The storage of the aquitard (the leaky confining layer) is included in the formula. A program denoted FINHOW2 is written to facilitate the calculation. Sensitivity of the solution to the confined versus unconfined conditions, fractured versus non-fractured conditions, and wellbore storage and skin effects is analyzed.Item Characterization of plant cation/h+ antiporters and how they can impact nutrition(2009-05-15) Morris, James LarryCalcium transporters regulate calcium fluxes within cells. Plants, like all organisms, contain channels, pumps and exchangers to carefully modulate intracellular calcium levels. Numerous Arabidopsis proteins have been characterized which can transport calcium. However, there are numerous genes whose products have not been fully characterized. One method I used to infer function was to analyze various promoter lengths of 17 putative cation transporters fused to reporter and to observe changes in the reporter expression in response to various stimuli. Using a more in depth approach I set out to characterize the function of AtCCX3. Here I show Arabidopsis AtCCX3 can suppress yeast mutants defective in vacuolar Na+ and K+ transport. AtCCX3-expressing yeast cells conferred Mn2+ sensitivity when highly expressed. Functional epitope tagged AtCCX3 fusion proteins were localized to endomembranes in plants and yeast. Expression of AtCCX3 increased in plants treated with NaCl, KCl and MnCl2 and caused increased Na+ accumulation and increased K+ transport. Ectopic expression of AtCCX3 in tobacco produced lesions in the leaves, stunted growth, resulted in the accumulation of higher levels of numerous cations and increased protein oxidation preceded alterations in leaf growth. These characteristics define AtCCX3 as an endomembrane localized transporter with biochemical properties distinct from previously characterized plant transporters. In the remaining studies I used the mouse model to determine how molecular changes to plants can improve the nutritional quality of the food. Previously, the cod5 M. truncatula mutant was identified which contains identical calcium concentrations to wild-type, but contains no oxalate crystals. Mice fed intrinsically labeled cod5 plants had 22.87% (p<0.001) calcium absorption compared to wild type plants. In a second study, using mice I examined if increased expression of a calcium transporter which increases calcium concentration 2-fold, alters bioavailable calcium. In mice feeding regimes (n = 120), I measured 45Ca-incorporation into bones, and determined that mice required twice the serving size of control carrots to obtain the calcium found in sCAX1-carrots. Together, these two studies demonstrate how the potential utility of removing calcium absorption inhibitors and fortifying vegetables can improve calcium bioavailability.Item Diffusion Preconditioner for Discontinuous Galerkin Transport Problems(2011-08-08) Barbu, Anthony PetruA simple Richardson iteration procedure converges slowly when applied to thick, diffusive problems with scattering ratios near unity. The current state of the art for overcoming this is to use a Krylov method with a diffusion preconditioner. However, the diffusion preconditioner must be tailored to the discretization of the transport operator to ensure effectiveness. We expand work from the bilinear discontinuous (BLD) finite element method (FEM) in two dimensions into a preconditioner applicable to all Discontinuous Galerkin FEMs in two and three dimensions. We demonstrate the effectiveness of our approach by applying it to the piecewise linear discontinuous (PWLD) FEM, which is notable for its flexibility with unstructured meshes. We employ a vertex-centered continuous FEM diffusion solution followed by local one-cell calculations to generate discontinuous solution corrections. Our goal is to achieve the same level of performance for PWLD and other methods, in two and three dimensions, as was previously achieved for BLD in two dimensions. We perform a Fourier analysis of this preconditioner applied to the PWLD FEM and we test the preconditioner on a variety of test problems. The preconditioned Richardson method is found to perform well in both ne and coarse mesh limits; however, it degrades for high-aspect ratio cells. These properties are typical for partially consistent diffusion synthetic acceleration (DSA) schemes, and in particular they are exactly the properties of the method that was previously developed for BLD in two dimensions. Thus, we have succeeded in our goal of generalizing the previous method to other Discontinuous Galerkin schemes. We also explore the effectiveness of our preconditioner when used within the GMRES iteration scheme. We find that with GMRES there is very little degradation for cells with high aspect ratios or for problems with strong heterogeneities. Thus we find that our preconditioned GMRES method is efficient and effective for all problems that we have tested. We have cast our diffusion operator entirely in terms of the single-cell matrices that are used by the discontinuous FEM transport method. This allows us to write our diffusion preconditioner without prior knowledge of the underlying FEM basis functions or cell shapes. As a result, a single software implementation of our preconditioner applies to a wide variety of transport options and there is no need to re-derive or re-implement a diffusion preconditioner when a new transport FEM is introduced.Item Effects of density and water availability on the behavior, physiology, and weight loss of slaughter horses during transport(Texas A&M University, 2007-04-25) Iacono, Christa MarieThe aim of this study was to determine the effects of density and provision of water on behavior, stress, and weight loss in slaughter horses during transport. A 16.2-m long, single deck, semi-trailer was divided into three compartments to create high, medium, and low density (5000, 4000, and 3000 kg per compartment, respectively) groups of slaughter horses. A total of six shipments containing 23 to 30 horses per shipment were transported in June and July of 2004 for 18 to 20 h. Horses were a variety of different breeds, ages, sexes, and body conditions, but were typical of slaughter horses. Jugular blood samples were taken from five horses in each of the three density treatments immediately before loading and after unloading at the completion of each shipment. All horses were weighed at the same time as the blood samples were collected. While the truck was stopped, horses in each of two compartments received water from three automatic water bowls in each side of a compartment. The water was provided for 1-h after 8 h of transport and then again just prior to unloading. The third, non-watered compartment served as a control for each of the 1-h watering sessions. Densities selected to receive water were alternated between shipments. The aggressive behavior of the horses for the six shipments was recorded using 12 video cameras installed in the trailer. All occurrences of aggressive behavior were counted from 15-min segments of video during 2-h intervals for each horse that was visible in each density group. Density did not significantly affect (P > 0.21) aggressive behavior, cortisol, serum chemistry profile, dehydration, and weight loss. Aggression level did not differ (P = 0.49) between the first and second halves of the shipments. Individual horses, rather than density, appeared to be the cause of aggressive behavior. The watered and non-watered groups did not differ (P > 0.54) in terms of aggression, cortisol, serum chemistry profile, dehydration, and weight loss. Density and provision of water did not significantly influence aggressive behavior, stress and weight loss in shipments of 18 to 20 h long during warm weather.Item Imaging Heterogeneous Objects Using Transport Theory and Newton's Method(2012-02-14) Fredette, NathanielThis thesis explores the inverse problem of optical tomography applied to two-dimensional heterogeneous domains. The neutral particle transport equation was used as the forward model to simulate how neutral particles stream through and interact within these heterogeneous domains. A constrained optimization technique that uses Newton's method served as the basis of the inverse problem. The capabilities and limitations of the presented method were explored through various two-dimensional domains. The major factors that influenced the ability of the optimization method to reconstruct the cross sections of these domains included the locations of the sources used to illuminate the domains, the number of separate experiments used in the reconstruction, the locations where measurements were collected, the optical thickness of the domain, the amount of signal noise and signal bias applied to the measurements, and the initial guess for the cross section distribution. All of these factors were explored for problems with and without scattering. Increasing the number of sources, measurements and experiments used in the reconstruction generally produced more successful reconstructions with less error. Using more sources, experiments and measurements also allowed for optically thicker domains to be reconstructed. The maximum optical thickness that could be reconstructed with this method was ten mean free paths for pure absorber domains and two mean free paths for domains with scattering. Applying signal noise and signal bias to the measured fluxes produced more error in the reconstructed image. Generally, Newton's method was more successful at reconstructing domains from an initial guess for the cross sections that was greater in magnitude than their true values than from an initial guess that was lower in magnitude.Item Increasing ventilation in commercial cattle trailers to decrease shrink, morbidity, and mortality(2009-06-02) Giguere, Nicole MarieA practical method of reducing aerosolized pathogens and environmental contaminants during commercial transportation could prove beneficial to the health and value of cattle. Having previously determined that there was very limited airflow within moving livestock trailers, an experimental treatment that increased cross-ventilation within commercial cattle trailers by installing aluminum scoops to punch-hole trailers was evaluated. Environmental factors including temperature, ammonia and carbon dioxide concentrations, and percent dry matter of excreted urine and fecal matter were evaluated, along with physiological factors, including complete blood count, serum electrolyte concentrations, percent weight loss, the presence of Salmonella, Escherichia coli, or Mannheimia haemolytica, and 30 day health data. The experiment consisted of two trials, each with two truckloads of 80 cattle each, for a total of 320 cattle. Temperature was evaluated in the center compartments of each trailer at five minute intervals throughout both trips. Ammonia concentrations were measured using passive dosimeters. Jugular blood samples, fecal grab samples, swabs of the terminal rectum and nasal swabs were obtained 8.5 to 10 hours post-transport from 20 cattle from each trailer. Increased ventilation resulted in lower temperatures and ammonia concentrations on both trips. Percent dry matter of excreted urine and fecal matter were inconclusive. There were no treatment effects for complete blood counts or electrolyte and basic chemistry panels, possibly because the cattle had access to both hay and water between transport and sampling, which allowed for recovery. Cattle in the ventilated trailer had an average weight loss of 4.7%, compared with 5.75% for the cattle in the control trailers. Sampling for E. coli O157:H7, Salmonella, and M. haemolytica showed very few positives, likely due to the good condition of the cattle prior to transport. During the 30 days post-transport, no cattle from either treatment required veterinary attention related to transport. The results indicate that increasing ventilation through the use of external air scoops has the potential to improve the health and well-being of cattle during transport.Item Inflammatory Gene Expression in Goats in Response to Transport(2012-10-19) Carter, MarkTransport, a common cause of stress in livestock, has been documented to increase cortisol, and epinephrine in goats. However, little is known about the timing of changes in the immune system in these stressed animals. The objective of this study was to determine whether expression of immune-related genes changes in goats that are exposed to transport stress. In this study, 15 Spanish-Boer goats ranging from 3 to 4 yrs of age were transported for 12 h. Goats were divided into 5 groups of 3 and placed in 1.219 m x 1.219 m pens. Blood samples were collected via jugular veni-puncture from each animal at 0 h, 3 h, 6 h, 9 h, and 12 h of transport, plasma and leukocytes were harvested for cortisol analysis and PCR analysis for gene expression. Data was analyzed using trailer location (group) as the experimental unit in a mixed model, repeated measures analysis of variance with compound symmetry and autoregressive covariance structures, depending on the best fit for each model. Percent weight losses were analyzed using a diagonal covariance mixed model. Hourly temperature humidity index (THI) values inside the trailer and from the shade were analyzed using a two-independent sample T-test. Cortisol concentrations were significantly elevated during transport (P<.049), indicating that goats experienced stressful events during hours of transport. Cortisol concentrations peaked after 6 hours, and returned to near basal concentrations after 12 h of transport. There was an overall trend for greater expression of many of the genes of interest to increase expression after 12 h of transport, but none were significantly different from pre-transport expression values. Overall, the data suggests that the goats transported during this study experienced transport stress, as indicated by the elevation in cortisol concentrations, but did not have significant changes in expression of the immune-related genes after 12 h of transport.Item Lagrangian methods for climatological analysis of regional atmospheric transport with an emphasis on Texas ozone exceedances(Texas A&M University, 2004-11-15) Dexheimer, Darielle NicoleA quantitative climatology of atmospheric transport in Texas is developed using previously described Lagrangian trajectory methods (Rogers and Bowman, 2001; Bowman and Carrie, 2002). The trajectories are computed using winds from 1979-2001 from the National Center for Environmental Prediction (NCEP) Reanalysis Project data set. Probability distributions are created for particle transport using trajectories from urban areas, making six-hourly particle distributions available from four urban areas in Texas. These probability distributions represent a quantitative understanding of regional air transport. Time-dependent Green's functions are calculated given initial conditions such as urban areas weighted with respect to population. The Green's functions describe how air from urban areas is transported through the atmosphere as a function of time. Summertime backward Lagrangian trajectories initialized at 5 Texas Commission on Environmental Quality (TCEQ) monitoring stations are grouped according to the ozone value recorded at the station at the initialization time of the trajectory. The directions of the trajectories in each group are used to determine the relationship between the transport characteristics of the circulation over Texas and regional-scale observations of pollutants. Synoptic conditions occurring at the time of summertime ozone exceedances at the 5 TCEQ stations are investigated in order to resolve what conditions are likely to coincide with ozone exceedances.Item Measure of Diffusion Model Error for Thermal Radiation Transport(2013-04-19) Kumar, AkanshaThe diffusion approximation to the equation of transfer (Boltzmann transport equation) is usually applied to media where scattering dominates the interactions. Diffusion approximation helps in significant savings in terms of code complexity and computational time. However, this approximation often has significant error. Error due to the inherent nature of a physics model is called model error. Information about the model error associated with the diffusion approximation is clearly desirable. An indirect measure of model error is a quantity that is related in some way to the error but not equal to the error. In general, indirect measures of error are expected to be less costly than direct measures. Perhaps the most well-known indirect measure of the diffusion model error is the variable-Eddington tensor. This tensor provides a great deal of information about the angular dependence of the angular intensity solution, but it is not always simple to interpret. We define a new indirect measure of the diffusion model error called the diffusion model error source (DME source). When this DME source is added to the diffusion equation, the transport solution for the angular-integrated intensity is obtained. In contrast to the variable-Eddington tensor, our DME source is a scalar that is conceptually easy to interpret. In addition to defining the DME source analytically, we show how to generate this source numerically relative to the Sn radiative transfer equations with linear-discontinuous spatial discretization. This numerical source is computationally tested and shown to reproduce the Sn solution for a number of problems. Our radiative transfer model solves a coupled, time dependent, multi-frequency, 1-D slab equation and material heat transfer equation. We then use diffusion approximation to solve the same problem. The difference due to this approximation can be modelled by a ?diffusion source?. The diffusion source is defined as an amount of inhomogeneous source that, when added to a diffusion calculation, gives a solution for the angle-integrated intensity that is equal to the transport solution.Item Measuring total longshore sediment transport with a LISST instrumented mini-sled.(Texas A&M University, 2006-04-12) Huchzermeyer, Erick KarlA surf zone sediment transport study was conducted in Jamaica Beach, Texas, using new oceanographic equipment. A mini-sled was constructed and outfitted with an instrument package that consisted of two velocimeters, one current profiler, three OBS's (Optical Back Scatter), and a Sequoia Instruments LISST (Laser in situ Scatteroineter and Transinissoineter). This instrumented sled was used to measure sand concentration and flow velocity across the surf zone. Using these two parameters we were able to determine longshore sand transport. The study provided an accurate measurernent of sand transport on a muddy coast. Previous methods for measuring total longshore sediment transport did not quantify the effect that mud-sized particles would have on OBS's. To circumvent this issue we used the LISST to measure sand concentration in the water. The LISST can measure sand concentration despite the presence of mud. During this study it appeared that sand transport peaks 10 cm above the sea bottom. The measured total longshore transport rate closely matched results from one equation for determining total longshore transport (Kamphius, 199 1). The CERC equation was also compared to the measured result.Item Numerical modeling of species transport in turbulent flow and experimental study on aerosol sampling(Texas A&M University, 2007-04-25) Vijayaraghavan, Vishnu KarthikNumerical simulations were performed to study the turbulent mixing of a scalar species in straight tube, single and double elbow flow configurations. Different Reynolds Averaged Navier Stokes (RANS) and Large Eddy Simulation (LES) models were used to model the turbulence in the flow. Conventional and dynamic Smagorinsky sub-grid scale models were used for the LES simulations. Wall functions were used to resolve the near wall boundary layer. These simulations were run with both two-dimensional and three-dimensional geometries. The velocity and tracer gas concentration Coefficient of Variations were compared with experimental results. The results from the LES simulations compared better with experimental results than the results from the RANS simulations. The level of mixing downstream of a S-shaped double elbow was higher than either the single elbow or the U-shaped double elbow due to the presence of counter rotating vortices. Penetration of neutralized and non-neutralized aerosol particles through three different types of tubing was studied. The tubing used included standard PVC pipes, aluminum conduit and flexible vacuum hose. Penetration through the aluminum conduit was unaffected by the presence or absence of charge neutralization, whereas particle penetrations through the PVC pipe and the flexible hosing were affected by the amount of particle charge. The electric field in a space enclosed by a solid conductor is zero. Therefore charged particles within the conducting aluminum conduit do not experience any force due to ambient electric fields, whereas the charged particles within the non-conducting PVC pipe and flexible hose experience forces due to the ambient electric fields. This increases the deposition of charged particles compared to neutralized particles within the 1.5?????? PVC tube and 1.5?????? flexible hose. Deposition 2001a (McFarland et al. 2001) software was used to predict the penetration through transport lines. The prediction from the software compared well with experiments for all cases except when charged particles were transported through non-conducting materials. A Stairmand cyclone was designed for filtering out large particles at the entrance of the transport section.Item Strong Suppression of Electronic Coherence Time by Flexural Phonons in Graphene --- Example of a New Dephasing Mechanism(2014-07-08) Zhao, WeiWe investigate decoherence of an electron in graphene caused by electron-flexural phonon interaction.We find out that the flexural phonons can produce dephasing rate comparable to the electron-electron one. The problem appears to be quite special because there is a large interval of temperatures where dephasing rate cannot be obtained using the golden rule. We evaluate this rate for a wide range of n and T and determine several asymptotic regions with temperature dependence crossing over from ?_?^(-1)?T^2 to? ??_?^(-1)?T when temperature increases. We also find ?_?^(-1) to be a non-monotonous function of n. These distinctive features of the new contribution can provide an effective way to identify flexural phonons in graphene through the electronic transport by measuring the weak localization corrections in magnetoresistance.Item Studies on Uptake of Thiamin Analogs by a Thiamin Deficient E. coli Mutant Strain(2012-11-28) Olivard, SarahThiamin transport in Escherichia coli is a model system to establish the tolerance of derivatives for transport into the cell. Since little is known about what types of thiamin derivatives may be successfully taken into the cell through the transport system, a series of thiamin derivatives are synthesized. A thiamin amino analog is synthesized and tested to determine the use of the analog as an alternate source of thiamin for growth of an E. coli thiamin mutant. Formate, acetate, and benzoate thiamin esters are synthesized and tested as alternate sources for growth of an E. coli thiamin mutant. Thiamin esters or amides may provide a scaffold for attaching other small molecules of interest to be imported into the cell by thiamin transport system. Thiamin containing formate, acetate, and benzoate esters were synthesized and tested as alternative growth source for thiamin using an E. coli mutant strain incapable of synthesizing thiamin. All three synthesized ester thiamin forms gave a zone of growth determined by disk-assay study. Also, an amino thiamin is synthesized to determine uptake through thiamin transport system by growth study using an E. coli mutant incapable of synthesizing thiamin. The growth curves resulting show concentration-dependent growth in the absence of natural thiamin, indicating amino thiamin is taken up by thiamin transport system as an alternate source of thiamin for growth. More characterization of the thiamin transport system is desired in order to develop thiamin conjugates of interest such as a photoaffinity probe for isolating thiamin-utilizing enzymes.Item The Effects of Prenatal Transportation on Postnatal Endocrine and Immune Function in Brahman Beef Calves(2013-07-25) Price, Deborah MichellePrenatal stressors have been reported to affect postnatal cognitive, metabolic, reproductive and immune functions. This study examined immune indices and function in Brahman calves prenatally stressed by transportation of their dams on d 60, 80, 100, 120 and 140 ? 5 d of gestation. Based on assessment of cow?s temperament and their reactions to repeated transportation it was evident that temperamental cows displayed greater pre-transport cortisol (P < 0.0001) and glucose (P < 0.03) concentrations, and habituated slower to the stressor compared to cows of calm and intermediate temperament. Serum concentration of cortisol at birth was greater (P < 0.03) in prenatally stressed versus control calves. Total and differential white blood cell counts and serum cortisol concentration in calves from birth through the age of weaning were determined. We identified a sexual dimorphism in neutrophil cell counts at birth (P = 0.0506) and cortisol concentration (P < 0.02) beginning at 14 d of age, with females having greater amounts of both. Whether weaning stress differentially affected cell counts, cortisol concentrations and neutrophil function of prenatally stressed and control male calves was examined. At 2 d post weaning, all calves had increased cortisol concentration (P < 0.0001) and neutrophil cell counts (P < 0.0001). However, in vitro production of reactive oxidative species by neutrophils was decreased (P = 0.0002) 2 d post weaning. Moreover, prenatally stressed calves demonstrated a larger (P = 0.0203) decrease in their immune function relative to control calves at 2 d post-weaning. Importantly, prenatally stressed calves took longer than controls to recover from the weaning stress. Additional studies are needed to clarify if prenatally stressed calves are more susceptible than control calves to pathogens during the post weaning period. Management practices to improve animal welfare and livestock production may need modification if follow-up studies demonstrate that prenatal stress also affects reproductive development, growth, performance and meat quality.Item Trajectory Simulations of H2O, O3, and CO in the Upper Troposphere and Lower Stratosphere (UTLS)(2014-05-05) Wang, TaoThe purpose of this work is to simulate water vapor (H2O), ozone (O3), and carbon monoxide (CO) in the upper troposphere and lower stratosphere (UTLS) using a domain-filling, forward trajectory model. The influx of H2O to the UTLS is largely determined by the large-scale troposphere-to-stratosphere transport in the tropics, during which air is dehydrated across the cold tropical tropopause. In the domain-filling, forward trajectory model, trajectories are initialized in the upper troposphere, and the circulation is based on reanalysis wind fields. Along the trajectories, winds determine the pathways of parcels and temperature determines the H2O content through an idealized saturation calculation. Compared with the Aura Microwave Limb Sounder (MLS) measurements, this simple advection-condensation strategy yields reasonable results for H2O in the stratosphere in terms of both seasonal variability and vertical structures. The detailed global dehydration patterns are also revealed from this model and it improves our understanding of the H2O and its transport within the UTLS. Besides H2O, ozone (O3) and carbon monoxide (CO) are also important trace gases in the UTLS linked to circulation, transport and climate forcing (for O3). Combined with simple parameterization of chemical production and loss rates from the Whole Atmosphere Community Climate Model (WACCM), we also managed to simulate O3 and CO transport in the UTLS via this trajectory model. The trajectory modeled O3 and CO show good overall agreement with satellite observations from the MLS and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) in terms of spatial structure and seasonal variability. The trajectory model results also agree well with the Eulerian WACCM simulations. Analysis of the simulated tracers shows that seasonal variations in tropical upwelling exerts strong influence on O3 and CO in the tropical lower stratosphere, and the coupled seasonal cycles provide a useful test of the transport simulations. Interannual variations in the tracers are also closely coupled to changes in upwelling, and the trajectory model can accurately capture and explain observed changes. This demonstrates the importance of variability in tropical upwelling in forcing chemical changes in the tropical UTLS. Trajectory modeling of O3 and CO can provide useful tests for simplified understanding of transport and chemical processes in the UTLS, and provide complementary information to the H2O simulations, which are primarily constrained by tropopause temperatures. This model is easy to use, easy to diagnose, and the Lagrangian perspective makes it exceptionally useful in studying transport processes within the UTLS.