Thesis (Ph.D.)--Cornell University, 1988. / Includes bibliographical references.

Thesis (Ph.D.)--Yale University, 1997. / Director: Jonathan D. Spence. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 326-338).

Separations coupled to mass spectrometry (MS) are widely used for large-scale protein identification in order to reduce the adverse effects of analyte ion suppression, increase the dynamic range, and as a deconvolution technique for complex datasets typical of cellular protein complements. In this work, matrix assisted laser desorption-ionization is coupled with ion mobility (IM) separation for the analysis of biological molecules. The utility of liquid-phase separations coupled to MS lies in the orthogonality of the two separation dimensions for all analytes. The data presented in this work illustrates that IM-MS relies on the correlation between separation dimensions for different classes (either structural or chemical) of analyte ions to obtain a useful separation. For example, for a series of peptide ions of increasing mass-to-charge (m/z) a plot drift time in the IM drift cell vs. m/z increases in a near-linear fashion, but DNA or lipids having similar m/z values will have very different IM drift time-m/z relationships, thus drift time vs. m/z can be used as a qualitative tool for compound class identification. In addition, IM-MS is applied to the analysis of large peptide datasets in order to determine the peak capacity of the method for bottom-up experiments in proteomics, and it is found that IM separation increases the peak capacity of an MS-only experiment by a factor of 5-10. The population density of the appearance area for peptides is further characterized in terms of the gas-phase structural propensities for tryptic peptide ions. It is found that a small percentage (~3%) of peptide sequences form extended (i.e., helical or β-sheet type) structures in the gas-phase, thus influencing the overall appearance area for peptide ions. Furthermore, the ability of IM-MS to screen for the presence of phosphopeptides is characterized, and it is found that post translationally modified peptides populate the bottom one-half to one-third of the total appearance area for peptide ions. In general, the data presented in this work indicates that IM-MS offers dynamic range and deconvolution capabilities comparable to liquid-phase separation techniques coupled to MS on a time scale (ms) that is fully compatible to current MS, including TOF-MS, technology.

A Matrix-assisted Laser Desorption/Ionization (MALDI) – Ion Mobility (IM) – Surface-induced Dissociation (SID) – Time-of-Flight (TOF) instrument with three different collision source configurations was developed in order to improve the SID performance in high throughput peptide sequencing. The first version of the instrument was equipped with an angle resolved SID source in order to maximize the collection efficiency of the SID scattering ions. An orthogonal TOF was also implemented as the second MS stage in this instrument to increase mass resolution. The second version of the instrument was developed towards simplifying the coupled configuration of the IM, SID and TOF components by using a combined SID/TOF source with a confinement ring electrode as the collision target. The fragmentation efficiency of SID in this configuration was increased up to 50% due to the surface normal impact angle used as compared with the results from a previous experiment using 45 degree impact angle. The third version of the instrument was equipped with a dual-source/dual-detector TOF to facilitate high throughput tandem analysis of peptides through simultaneous separation, fragmentation and mass analysis, while retaining precursor ion identity in the same experimental sequence. A series of small organic molecules, model peptides and tryptic peptides from a protein digest were analyzed to demonstrate the utility of these new designs for enhanced SID performance and peptide sequencing capability. Finally, a new mobility drift cell using a periodic focusing mechanism has been designed and fabricated to replace the previous uniform field drift cell. Improvement in ion transmission has been observed in the periodic focusing drift cell instrument without sacrificing the mobility resolution.

The purpose of this study is to examine what effect social background may have on the timing of becoming a parent in Sweden. By applying event-history techniques to data from the Swedish level of living survey (LNU) we try to separate the direct from the indirect effect of social background on timing of first childbearing. Few previous studies have focused on characteristics of social background and analysis of intergenerational effects on the age of becoming a parent. In this study, we show that the risk of becoming a parent is different for those who are mobile than for the socially non-mobile. The effect of social background on the propensity of becoming a parent is not just indirect via persons own educational careers. When we control for own educational level much of the impact of social background on the propensity of becoming a parent remains. We clearly show the existence of a significant direct effect of social background on the propensity to become a parent.

The purpose of this study was to examine the relationship between teacher quality variables, student demographic variables, and student performance in order to determine the influence teacher quality variables have on student performance in one large school district. The population for this study included 69 schools during the 2007-2008 school year within one large suburban school district. Included in this study were 47 elementary schools, 14 middle schools, and 8 high schools. In this three-phased study, descriptive correlations were examined, t-tests were conducted comparing each of the variable sets, and partial correlations were conducted in order to determine the strength of associations between teacher quality variables and student performance variables. Findings from this study showed several strong and significant associations. When comparing the highest and lowest quartile of schools based on average years of teaching experience, percentage of within-district transfers, and total teacher mobility, there was a significant difference seen in both the percentage of economically disadvantaged (ED) students and percentage of African American and Hispanic students combined. Further analysis showed a significant difference between the top and bottom quartiles of percentage of ED students and percentage of African American and Hispanic students combined and their performance in both math and reading. Findings showed that teaching experience was negatively associated with student performance in reading and math, however, there was a smaller association in math. Controlling for within-district teacher transfers had a small to medium association between African American and Hispanic students combined and commended performance or meeting standard in math and reading. When controlling for percentages of total teacher mobility (leavers + movers) from campuses, there was a strong negative, partial correlation between percentage of ED students and performance in math (commended only) and reading. Implications for practitioners include the need to improve school leadership, improve working conditions, provide more and better professional support, create incentives to work in challenging schools, improve preparation for work in challenging schools, streamline hiring placement policies, create a coherent set of policies to close the staffing gap, and provide greater funding targeted to student needs.

This thesis is issued in collaboration with the Jet Propulsion Laboratory (JPL) in Pasadena, California. JPL's primary function is the construction and operation of robotic planetary spacecraft. At the time being JPL has 22 spacecraft and 10 instruments conducting active missions. The "Dark Ages" represent the last frontier in cosmology, the era between the genesis of the cosmic microwave background (CMB) and the formation of the first stars. During the Dark Ages, when the Universe was unlit by any star, the only detectable signal is likely to be that from neutral hydrogen (HI). The HI absorption occurs in dark matter-dominated overdensities, locations that will later become the birthplaces of the first stars. Tracing this evolution will provide crucial insights into the properties of dark matter and potentially reveal aspects of cosmic inflation. This could be accomplished using a radio telescope located on the far side of the Moon, the only site in the solar system shielded from human-generated interference and, at night, from solar radio emissions. Our objective has been the development of the concept of an autonomous rover that would be capable of deploying a large number of low frequency radio antennas on the lunar surface. This is an enabling task for the eventual creation of a radio telescope. The project at Halmstad University was divided into three sub-projects, where our area of responsibility has been the development of a concept of the rover's mobility system. The result of the project is the concept of a "Rocker-Bogie" suspension system, created in a 3D-environment. A concept which underwent a series of digital analyses and simulations to ensure the compliance with required specifications. / Detta examensarbete är utfört i samarbete med Jet Propulsion Laboratory (JPL) i Pasadena, Kalifornien. JPL's primära funktion är konstruktion och drift av robotiserade rymdfarkoster. För tillfället har JPL 22 rymdfarkoster och 10 instrument i aktiva uppdrag. Den "mörka tiden" representerar den sista utposten i kosmologi, eran mellan uppkomsten av den kosmiska bakgrundsstrålningen (CMB) och bildandet av de första stjärnorna. Under den "mörka tiden", när universum inte var upplyst av någon stjärna, var den enda detekterbara signalen sannolikt från neutralt väte (HI). HI-absorptionen sker i mörk materia-dominerade överdensiteter, platser som senare blir födelseplatserna för de första stjärnorna. Att spåra denna utveckling kommer att ge viktiga insikter i egenskaperna hos mörk materia och eventuellt ge information om universums expansion. Detta kan åstadkommas med hjälp av ett radioteleskop på baksidan av månen. Den enda platsen i vårt solsystem avskärmad från störningar från jorden, och på natten även från solens strålning. Vår uppgift har varit att utveckla ett koncept på en autonom rover som ska placera ut ett stort antal lågfrekvensantenner på månytan. Detta är ett nödvändigt steg för det eventuella anläggandet av ett radioteleskop. Projektet vid Högskolan i Halmstad delades upp i tre delprojekt, där vårt ansvarsområde har varit att utveckla ett koncept för roverns drivsystem. Resultatet av projektet ett koncept på ett "Rocker-Bogie"-hjulupphängningssystem, skapad i en 3D-miljö. Ett koncept som har genomgått en serie av digitala analyser och simuleringar för att säkerställa överensstämmelse med krav och önskemål.

Individuals with Multiple Sclerosis commonly use assistive mobility devices, such as rollators, to compensate for their mobility impairments. However, the effect of these devices on their foot placement during gait has not been explored in the community. The objective of experiment one was to develop and validate a tool that quantifies medio-lateral foot placement characteristics during rollator use. In this study, a technique was developed for an instrumented rollator (i.e. iWalker) and validated against a Vicon motion capture system in able-bodied young adults. The two systems were in strong agreement. The objective of experiment two was to apply this iWalker-based technique to individuals with Multiple Sclerosis to identify environment-related foot placement changes. This study revealed that step width variability, but not step width, can be influenced by certain outdoor environments. Therefore, environmental context is important to consider when investigating user-device interactions and factors responsible for safe mobility in this population.

Intergenerational mobility is of interest to social scientists, in part due to the persistence of the quest for the “American Dream”. Intergenerational mobility is a gauge of the opportunities each group has to increase their privilege, class, and income. In addition, it helps researchers understand the way our society creates class structures. Many studies have addressed intergenerational mobility, focusing on socioeconomic status (socioeconomic status) of fathers and its effect on their sons. Other studies have looked at father’s effect on son’s and daughter’s occupational mobility, but the effect of father’s socioeconomic status on daughter’s socioeconomic status has been overlooked thus far. This study examined the intergenerational mobility of socioeconomic status and if there are differences in the transmission of father’s socioeconomic status to their sons and daughters. Secondary data analysis of the National Longitudinal Survey of Youth (1979-2002) was used for the analysis. A model was created in order to examine three sets of relevant theories: individual, structural, and gender-level. Univariate, bivariate and ordinary least squares (OLS) regression were utilized for analysis. Bivariate analysis shows that sons have higher socioeconomic status than daughters. OLS regression results indicate that father’s socioeconomic status has a positive effect on children’s socioeconomic status, net of other factors, but no statistical difference was found between sons and daughters. / Thesis (M.A.)--Wichita State University, College of Liberal Arts and Sciences, Dept. of Sociology