Typically developing Spanish-English bilingual children's production of twelve grammatical morphemes was analyzed for accuracy and described as a function of their English mastery, as indexed by mean length of utterance (MLU). Results revealed positive trends in morpheme accuracy as MLU increased. Despite a large degree of between subject variability, the data demonstrated general patterns that were consistent with previous literature, namely that the rate and trajectory of morpheme acquisition differs from monolingual norms, and that particular morphemes are predictably more and less challenging for bilingual children to produce accurately. MLU "cut-points" were suggested based on functional breaks in accuracy for several morphemes. / text

Birthweight is one of the most important health indicators for a newborn infant. Birthweight at either the lower or higher end is associated with adverse health outcomes in later life. In recent years, birthweight distribution in the United States has shifted to the lower end. This dissertation uses US vital statistics data from 1989 to 2007 to document recent birthweight trends in the US and examines the possible causes behind the trends. Results are reported for all births and by race/ethnicity/nativity. Descriptive analysis suggests that the lowering birthweight trend is the result of the rapid increase of lower-birthweight multiple births and decreasing birthweight among singleton births. The lowering birthweight is reflected in all birthweight measures. Low-birthweight rate is rising, mean birthweight is declining, and the proportion of macrosomic infants is decreasing. While this trend is most pronounced among US-born non-Hispanic whites and least among non-Hispanic blacks, it is prevalent among all race/ethnicity/nativity groups. Regression results suggest that much of the birthweight trend can be explained by shortened gestational age but common maternal socio-demographic, health and behavioral, and health care and medical intervention factors cannot fully explain the birthweight trend. Regression decomposition concludes that both the trends in maternal factors and the changes in the effects of these factors on birthweight contribute to the birthweight trend. Trend in gestational age is the biggest contributor, contributing more than 100% to the birthweight trend, while improvement in education, reduction of smoking during pregnancy and improvement in prenatal care have slowed down the birthweight decrease. Further research needs to be done to identify factors leading to the recent birthweight trend that are not available from the vital statistics. / text

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(エネルギー科学) / 甲第19092号 / エネ博第316号 / 新制||エネ||64 / 32043 / 京都大学大学院エネルギー科学研究科エネルギー基礎科学専攻 / (主査)教授 木下 正弘, 教授 森井 孝, 教授 片平 正人 / 学位規則第4条第1項該当

Despite the importance of single particle motion in biological systems, systematic inference approaches to analyze particle trajectories and evaluate competing motion models are lacking. An automated approach for robust evaluation of motion models that does not require manual intervention is highly desirable to enable analysis of datasets from high-throughput imaging technologies that contain hundreds or thousands of trajectories of biological particles, such as membrane receptors, vesicles, chromosomes or kinetochores, mRNA particles, or whole cells in developing embryos. Bayesian inference is a general theoretical framework for performing such model comparisons that has proven successful in handling noise and experimental limitations in other biological applications. The inherent Bayesian penalty on model complexity, which avoids overfitting, is particularly important for particle trajectory analysis given the highly stochastic nature of particle diffusion. This thesis presents two complementary approaches for analyzing particle motion using Bayesian inference. The first method, MSD-Bayes, discriminates a wide range of motion models--including diffusion, directed motion, anomalous and confined diffusion--based on mean- square displacement analysis of a set of particle trajectories, while the second method, HMM-Bayes, identifies dynamic switching between diffusive and directed motion along individual trajectories using hidden Markov models. These approaches are validated on biological particle trajectory datasets from a wide range of experimental systems, demonstrating their broad applicability to research in cell biology.

Modern engines are faced with increasingly stringent requirements for reduced fuel consumptionand lower emissions. A technique which can partly be used to reduce emissionsof nitrogen oxides is recirculation of combusted gases (Exhaust Gas Recirculation, EGR). Ingasoline engines, it also has the advantage that it can save fuel by reducing pumping losses.To large mixture of EGR in the air to the cylinders will however affect the combustion stabilitynegatively. To investigate EGR rate and dynamics with respect to different actuatorinputs, the thesis develops an engine model that includes EGR. The model focus on the airflow in the engine and extends an existing mean value engine model. Two types of EGRsystemare investigated. They are short-route EGR which is implemented between intakemanifold and exhaust manifold and long-route EGR which is implemented between compressorand turbine. The work provides a simulation study that compares both stationaryand transient properties of the two EGR-systems, such as fuel consumption, maximum EGR,and rise time with respect to different actuators.

Haemoglobin concentration is becoming a widely popular parameter to use to assess physiological condition within a broad range of species. Assessments of large populations would preferable be done in field to receive quick results and avoid confounding factors associated with transport of blood. A validation study is here performed to see how well the point-of-care device HemoCue Hb 201 + can assess haemoglobin concentration on avian blood. Nucleated erythrocytes have previously been pointed out as something that makes it problematic to apply HemoCue Hb 201 +, designed for human blood, on avian blood. Here it is shown that HemoCue Hb 201 + accurately can estimate haemoglobin concentration for chicken-, tinamou-, and ostrich blood. However, manipulation of ostrich cells, to yield a larger mean corspuscular volume, results in HemoCue Hb 201 + overestimating haemoglobin concentration. A large mean corpuscular volume could therefore be something that impair accuracy in values retrieved with HemoCue Hb 201 +. This study shows that HemoCue Hb 201 + seems possible to apply on avian blood to some extent, but highlights the importance of validation studies when applying this device on new species.

The heterogeneous condensation of a vapour onto a substrate is a key step in a wide range of chemical and physical process that occur in both nature and technology. For example, dust and pollutant aerosol particles, ranging in size from several microns down to just a few nanometers, serve as cloud condensation nuclei in the atmosphere, and nanoscale structured surfaces provide templates for the controlled nucleation and growth of variety of complex materials. While much is known about the general features of heterogeneous nucleation onto macroscopic surfaces, much less is understood about both the dynamics and thermodynamics of nucleation involving nanoscale heterogeneities. The goal of this thesis is to understand the general features of condensation of vapours onto different types of nanoscale heterogeneity that range in degree of solubility from being insoluble, to partially miscible through to completely miscible. The heterogeneous condensation of the Lennard-Jones vapour onto an insoluble nanoscale seed particle is studied using a combination of molecular dynamics simulations and thermodynamic theory. The nucleation rate and free energy barrier are calculated from molecular dynamics using the mean first passage time method. These results show that the presence of a weakly interacting seed has no effect on the formation of small cluster embryos but accelerates the rate by lowering the free energy barrier of the larger clusters. A simple phenomenological model of film formation on a small seed is developed by extending the capillarity based liquid drop model. It captures the general features of heterogeneous nucleation, but a comparison with the simulation results show that the model significantly overestimates the height of the nucleation barrier while providing good estimates of the critical film size. A non-volatile liquid drop model that accounts for solution non-ideality is developed to describe the thermodynamics of partially miscible and fully miscible droplets in a solvent vapour. The model shows ideal solution drops dissolve always spontaneously, but partially miscible drops exhibit a free energy surface with two minima, associated with a partially dissolved drop and a fully dissolved drop, separated by a free energy barrier. The solubility transition between the two drops is shown to follow a hysteresis loop as a function of system volume similar to that observed in deliquescence. A simple lattice gas model describing the absorption of mono-layers of vapour onto the particle is also developed. Finally, molecular dynamics simulation of miscible and partially miscible binary Lennard-Jones mixtures are also used to study this system. For all cases studied, condensation onto the drop occurs spontaneously. Sub-monolayers of the solvent phase form when the system volume is large. At smaller system volumes, complete film formation is observed and the dynamics of film growth are dominated by cluster-cluster coalescence. Some degree of mixing into the core of the particle is observed for the miscible mixtures for all volumes. However, mixing of the solvent into the particle core only occurs below an onset volume for the partially miscible case, suggesting the presence of a solubility transition similar to the one described by the thermodynamic model.

This work explores the hydraulic performance of a wastewater lagoon system located in San Antonio, Bolivia. The system consists of one facultative pond and two maturation ponds in series and is managed through a locally elected water committee. A tracer study was performed on the primary facultative pond and an analysis of the solids accumulation on the bottom of the facultative lagoon was also performed. The results were used to generate residence time distribution curves and provide an estimate of mean residence time in the system. The data was used to examine hydraulic efficiency as it relates to short-circuiting and dead zones. A sludge study accumulation study was performed using the white towel method and the resulting measurements were interpolated to determine a total estimated sludge volume of 169 m3 (which is 8% of the facultative pond volume). An orange study was also performed to assess the surface flow pattern in the system. The results were compared with a computational 2-d model. The 2-d model incorporated the estimated sludge distribution and provided a good fit for the tracer dye concentrations measured in the field over the 12 day study period. Simple models such as the Tanks in Series and the Completely mixed model were evaluated and abandoned because of their inability to model the physical behavior in the system. The Completely mixed model did however perform better than the Plug flow model. After comparing the tracer results from the reactor models that were considered: Tanks in Series, Completely mixed fluid, manual interpolation and the results from the 2-d cfd flow simulation, the results that provided the best fit for the data over 12 days was the manual interpolation method at a flow rate of 98 m3/day and configuration D at 60 m3/day. However, because of uncertainty as to what depth to obtain a representative area for the 2-d simplification and sensitivity to flow; all four configurations were considered for estimating the MHRT at the lowest measured flow rate of 60 m3/day. The results at a flow rate of 60 m3/day varied between 10.88 and 13.04 days for the MHRT with a hydraulic efficiency that varied between 33-51.6% (accounting for sludge volume). This is much shorter than the actual nominal retention time of 37 days and the design nominal retention time of 26 days. As a result it was concluded that short-circuiting was occurring in the facultative lagoon.

Methods of component mode synthesis, such as Craig and Bampton reduction, are known to generally yield more accurate results in deformable multibody dynamics. The main shortcoming of those methods is that they are intuitively based. Recently Nikravesh developed a reduction method called mode condensation which is derived from the equations of motion and yields the same results as Craig and Bampton reduction. In this dissertation, it is proven that these two methods span the same column space; therefore, they should yield identical results. We propose that mode condensation provides an analytical justification for Craig and Bampton reduction. Test results suggest that Craig and Bampton reduction and mode condensation are appropriate for a broader range of applications because their column space matches up well with the conditions under which the deformable body is restrained. Although Guyan reduction preserves exact solutions for static problems, its applications shall be limited to low frequency excitation because of raised eigen-frequencies. Modal truncation is not recommended for use in multibody dynamic settings because it lacks the ability to receive forces and displacements at the moving boundary. Another issue addressed in this dissertation is the misconception that if mean axes are adopted as the moving reference frame, only free-free modes should be used for model reduction. It was not clear how a restrained deformable body with mean axes can be condensed properly. We have shown that the conventional (nodal-fixed) mode shapes can be used with mean axes as long as the transformation matrix has full rank and contains complete rigid-body mode shapes.

In this thesis, portfolio optimisation is used to evaluate if a specific sample of portfolios have a higher risk level or lower expected return, compared to what may be obtained through optimisation. It also compares the return of optimised portfolios with the return of the original portfolios. The risk analysis software Aegis Portfolio Manager developed by Barra is used for the optimisations. With the expected return and risk level used in this thesis, all portfolios can obtain a higher expected return and a lower risk. Over a six-month period, the optimised portfolios do not consistently outperform the original portfolios and therefore it seems as though the optimisation do not improve the return of the portfolios. This might be due to the uncertainty of the expected returns used in this thesis.