A fundamental problem in biochemistry is how molecular machines convert chemical potential energy into mechanical work. Here, this problem is addressed in terms of how a proton gradient (ΔpH) drives anthrax toxin transmembrane protein translocation with a given directionality. One model to explain this phenomenon is a charge-state Brownian ratchet, wherein movement is biased by asymmetries across the membrane. Acidic residues in the substrate are protonated on the lower pH starting side, thus allowing them to pass through the cation-selective protective antigen (PA) channel. Movement can occur in either direction according to Brownian motion, but acidic residues that reach the higher pH of the destination are deprotonated, preventing retrotranslocation and resolving movement in one direction.

This model is probed through the use of planar lipid bilayer electrophysiology to analyze the charge requirements of the model substrate LF_N, the binding domain of the natural substrate lethal factor. Acidic residues are necessary and sufficient for ΔpH-driven translocation provided the starting side pH is low enough to sufficiently protonate the residues. Their position in the sequence, just before LF_N's folded domain, plays a key role in substrate unfolding. Basic charges are important for initiation into the channel and to chaperone deprotonated acidic residues during translocation.

Further work by Sarah Wynia-Smith confirms the importance of acidic residues just before LF_N's folded domain and points to the existence of electrostatic translocation barriers in the PA channel. I identify key residues in the upper portion of the channel's β barrel that contribute to its cation selectivity. These residues also prove to play a significant role in substrate initiation and translocation, supporting the role for a charge gate in the channel that prevents retrotranslocation.

Finally, secondary structure of the translocating substrate is analyzed. LF_N translocates in a compact helical state nucleated by the channel's α clamp, a nonspecific helix-binding site recently identified by Geoffrey Feld. α clamp-induced helix formation lowers a previously identified but uncharacterized translocation barrier, and substrates that cannot form helices cannot translocate. This suggests a mechanism wherein helix melting, coupled to the electrostatic ratchet, drives translocation-coupled substrate unfolding.

This project looks at American employment policy development between the 1930s and the 1990s and asks why government policies did not do more to ensure that there was enough employment for all would-be workers. I start with two key premises: first, that sufficient employment is essential to America's economic goals, both at a national level and at an individual level; second, that in America, paid, private employment has long been a marker of social inclusion, which makes access to stable and secure work even more important. This means that the limited scope of employment policy -- particularly the general lack of intervention to guarantee sufficient jobs -- is puzzling. I follow a case study approach, analyzing employment policy in three periods: the New Deal, the Great Society, and the Reagan Revolution. Using extensive archival material I demonstrate that America's liberal tradition has created an enduring constraint on employment policy: enshrining the responsibility to obtain work as individual rather than governmental and mandating that the government minimize its labor market intervention.

I break this liberal constraint down into two ``currents'' that pertain to employment. The first current -- work-as-citizenship -- establishes a tie between paid private employment and social citizenship, and further instructs that individuals must obtain such work for themselves. The second current -- labor-market anti-statism -- restricts federal intervention in the labor market, particularly restraining governmental efforts to create employment outside the private sector and imposing additional conditions on the employment interventions the government can take.

Between the 1930s and 1990s there were periodic challenges to the currents' boundary condition on employment policy. The elite level policy debates within the executive branch that embodied these challenges serve as my dissertation's empirical sites of investigation. These challenges, resulting from both economic and political circumstances, resulted in a variety of policy adaptations that stretched the liberal currents' limits, though the boundary condition itself remained intact. However, employment policy debates and outcomes in the 1980s-1990s also show that there is potential for work-as-citizenship to be leveraged as a basis for employment policies that ensure greater economic stability for all Americans.

This study examines the relationship between rap music and internal colonization in Oakland, California from 1965-2010. As rap music continues to gain exposure and popularity, hip-hop culture has increasingly become a topic in the social sciences and humanities. Most studies of hip-hop culture have predominately focused on the mass-market trend toward worldwide commercialization of rap rather than fully examining how underground units continue to inform and innovate the mass trend. Inadequate attention is currently paid to the political development of rap as an underground narrative from a single location. Using primary sources from Oakland, this project explores rap's development from its origins in the "war" between the Black Panther Party (BPP) and COINTELPRO efforts. I argue two points. First, the messages in Oakland rap were shaped and influenced by the militant, radical, and political nature of the BPP in a way that mainstream rap music was not. Second, the styles of Oakland rap blended into a robust local brand before the scene gained a modicum of popular attention--while the New York/Los Angeles paradigm was in the spotlight. This raises significant questions about the agenda setting role of local rap artists--namely, their ability to create messages and styles of music that are resistant to co-optation even while achieving popularization and commercialization. As such, this study offers new insights into urban politics and addresses fundamental questions of power and equality in a liberal democracy.

This study sought to examine the ways in which employment flexibility – a novel psychological construct defined as one’s willingness to work under a variety of different employment conditions – impacts the job-search process of recent college graduates. Specifically, this study aimed to investigate the relationships between employment flexibility and the following antecedents, behaviors, and outcomes of job-searching: number of job interviews received, number of job offers received, career adaptability, job-search intensity, job-search strategy, and job-search self-efficacy. Additionally, this study sought to develop a measure of employment flexibility as well as to provide initial evidence of construct validation.

The first step in accomplishing the goals of this study was to develop a measure of employment flexibility, the Employment Flexibility Scale (EFS). The EFS was developed based on the theoretical underpinnings of employment flexibility- circumscription and compromise (Gottfredson, 2002; 2005) and underemployment theory (Feldman, 1996). After an initial item development process, a reliability analysis and an exploratory factor analysis (EFA) was conducted in a sample of 204 of recent college graduates. Results from this first study suggested that the EFS was a reliable measure consisting of three factors: Person-Job Mismatch Flexibility, Resources Mismatch Flexibility, and Relational Mismatch Flexibility. After this initial exploration of the EFS, a second study was undertaken to confirm this three-factor structure of the EFS.

Study Two was completed with a new sample of 123 recent college graduates. Data collected from this sample was used to conduct a confirmatory factor analysis (CFA). Results from the CFA corroborated that the EFS has a stable three-factor structure. Finally, a third study was conducted to investigate the specific hypotheses guiding this research study.

Study Three was conducted among a new sample of 201 of recent college graduates. Participants in this study were asked to complete a variety of self-report measures. Correlational and regression analysis of the data collected in this study indicated that employment flexibility was related to a number of important job-search variables. Specifically, this study found that employment flexibility was positively related to job-search intensity, career adaptability, and an exploratory job-search strategy. Additionally, results from this study provide insights into the ways in which employment flexibility operates within the recent college graduate population. In general, it appears that recent college graduates are moderately employment flexible, and have the least flexibility toward pay underemployment and hours underemployment (i.e., Resources Mismatch Flexibility). The results of this study serve as the foundation to discuss the implications for practice and future research.

The structure of the low-density lipoprotein receptor extracellular portion has been determined. The document proposes a mechanism for the release of lipoprotein in the endosome. Without this release, the mechanism of receptor recycling cannot function.