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Spasticity is a clinical condition that may develop in people with central nervous system injuries. It is believed that spasticity results from changes in the excitability of the stretch reflex pathways manifesting clinically as a velocity dependent increase in resistance to passive movement (RTPM) and exaggerated tendon jerks. Stretch reflex excitability is influenced by neural (e.g. feed-forward and feedback mechanisms) and biomechanical components (e.g. muscle length). The objective of this work was to quantify the stretch reflex parameters of the biceps brachii under different initial conditions (amplitude of applied torque, initial muscle length, initial voluntary activity, head position) in non-impaired (NI) volunteers and stroke patients (SP) with diagnosed upper limb spasticity and objectively evaluate their differences. A biomechanical device was designed to provide a 90 ms initially applied torque controlled stretch to the biceps brachii. The stretch reflex response was recorded using surface electromyography and angular displacement with a potentiometer. Stretch reflex characterisation was done on EMG data collected 150 ms before and to complete 450 ms after the perturbation. The outcome measures were the amplitude of the rectified reflex response and, the latency, rise time and duration reflex response. Lower amplitudes, shorter latencies and longer durations were observed in the poststroke populancn when compared to the non-impaired volunteers. Amplitude results were unexpected. However latencies and durations suggest increased stretch reflex excitability. Significant differences dependent on the initial conditions were found within the non-impaired volunteers. No differences were found in the post-stroke population. These latter results suggest lack of modulation of the stretch reflex excitability after stroke. More research is necessary to understand the relationship between the changes in the stretch reflex excitability and the clinical concept of spasticity and the importance of their quantification to improve the quality of life of people with neurological lesions.

Mobile group II introns are ribozymes and mobile genetic elements found in all branches of life. They consist of a highly structured intron RNA that encodes a reverse transcriptase (RT). This RT is utilized during retrohoming to synthesize a full-length DNA copy (cDNA) of the intron RNA which is then integrated into new genome locations. One theory suggests that RTs evolved from an RNA Dependent RNA Polymerase (RDRP) that originated in the RNA World. These ancestral RDRPs served to propagate genetic material, and during the transition to DNA-based life, RDRPs evolved into RTs. Recent structural data for Geobacillus stearothermophilus Group II Intron RT (GsI-IIC RT) suggests a close evolutionary relationship between RDRPs and group II intron RTs, including a strikingly similar RT active site and regions that function in binding the template and primer. To further probe this evolutionary relationship rational mutations were introduced into GsI-IIC RT that affected rNTP incorporation ability. Group II introns have also potentially evolved characteristics like higher fidelity and processivity compared to other RTs due to stringent accuracy requirements when reverse transcribing the catalytically active and highly structured intron RNA. Host-encoded group II intron-like RTs that have acquired other functions often have substitutions for the conserved A residue in the YADD motif at the RT active site. This suggests that the active site can be modified by evolutionary pressures to suit diverse activities. This tolerance was exploited to mutate the highly conserved YADD motif to study structure-function relationships between conserved features of previously uncharacterized classes of RTs. Current laboratory data suggests that the YXDD motif can be modified to modulate different activities, although other crucial complementary or compensatory mutations are likely necessary. Through this work I obtained data that suggests group II intron RTs evolved from ancestral RdRPs, that their constricted active site might serve to increase fidelity, and that their conserved active site motif can be modified to modulate biochemical activities.

This dissertation examines how U.S. immigration laws and enforcement practices have impacted the lives of Salvadoran immigrant and deported men and their families. Based on the experiences of 40 Salvadoran immigrant men and 40 Salvadoran deported men, I found that they experienced the effects of the U.S. immigration enforcement regime in several distinct and interrelated ways. First, as Salvadoran immigrants arrived to the U.S. many faced inclusionary and exclusionary immigration laws. While some Salvadoran immigrants benefited from immigration laws, many Salvadoran immigrants have been disproportionately targeted due to their ethnic identity, gender, and working class background. Secondly, Salvadoran immigrant and deported men faced immigration laws and enforcement actions that affected their ability to fulfill their fathering roles and responsibilities as they were criminalized and deported from the U.S. Thirdly, Salvadoran immigrant and deported men shared that their children experienced the negative spill over effects of immigration laws and enforcement practices in their lives in the form of multigenerational punishments. These punishments manifested in the form of social, economic, emotional, and physical consequences. Similarly, Salvadoran immigrant and deported men shared that their romantic partners experienced the harmful effects of immigration laws and policies in the form of intragenerational punishments. These punishments manifested in the form of physical, emotional, and immigration consequences. Fourth, as Salvadoran immigrant men migrated to the U.S. and deported men returned to El Salvador many struggled with their membership and sense of belonging. Salvadoran immigrant and deported men specifically shared how they navigated different exclusionary practices by U.S. and Salvadoran governments, institutions, laws and policies, employers, and everyday people. In response, many engaged in constructing alternative forms of membership and belonging. Lastly, Salvadoran immigrant and deported men shared their understandings of laws, how they positioned themselves to laws, and how they responded to these harmful laws and enforcement actions in the form of resistance and mobilization strategies. This study ultimately demonstrates how immigrant fathers and their families navigate their lives and relationships under the U.S. immigration enforcement regime. Future studies may find that these experiences relate to other immigrant and deported fathers in the United States and abroad.

As the United States experiences another increase in anti-immigrant laws and targeted enforcement practices of the undocumented community, immigrant rights organizations are responding with mobilization strategies as forms of resistance. Through interviews and observations with immigrant rights advocates in Los Angeles, I identified six mobilization strategies. These include: (1) educational and awareness campaigns; (2) counter surveillance; (3) legal representation efforts; (4) non-violent protest and demonstrations; (5) the New Sanctuary Movement and Sanctuary Cities; and (6) “Get Out the Vote” campaigns. Each of these strategies responds to a specific form of repression and illustrates how immigrant rights groups respond to U.S. immigration agencies’ efforts to reinforce power relations, fear and panic, deception, surveillance, lack of fair and due process, threats to the unity and solidarity among immigrant rights groups, and other harmful effects. These mobilization efforts reveal how advocates and organizations challenge the institutions by establishing leaders and advocates from this community. Also, these strategies reveal the particular sort of power relationship within which migrants and immigrant rights organizations are struggling. The variation among these six strategies demonstrates how mobilization strategies are fluid and changing based on the challenges migrants face at a specific time and place. As a result, advocates in these organizations were found to focus on these six strategies to contest immigration related legal violence and migrant illegality efforts in Los Angeles in 2016. Further analysis could focus on how legal violence and migrant illegality shape the experiences of the undocumented community in the post-2016 election.

Public housing authorities (PHAs) have enforced banishment since the late 1980s by granting police the authority to ban non-residents from public housing neighborhoods and arresting them for trespassing upon violating the ban. PHAs justify banishment by stating that issuing bans and arrests for trespassing aid in crime prevention by removing non-residents who may commit criminal acts if left unguarded. Nonetheless, there has been no scientific evidence to suggest that banishment works to reduce crime. Similarly, the role community policing can play in enforcing banishment is unclear and scarce research has considered the effects of banishment on racial and ethnic minorities at neighborhood and individual levels. To address these issues this three-part study examined the enforcement of banishment on Kings Housing Authority (KHA; Southeast, US) public housing property from 2004-2012. Collectively these studies address the following overarching research questions: Does banishment reduce crime in public housing neighborhoods? Does banishment disproportionately target racial and ethnic public housing neighborhoods? Does banishment prevent banned individuals from re-offending in public housing? Does banishment disproportionately ban racial and ethnic individuals? What are the residential perceptions of banishment and its effectiveness? How does race and ethnicity affect perceptions of banishment and its effectiveness? Results suggest that banishment is better at reducing property crime than violent crime, though the reductions are modest at best. Increases in bans predicted decreases in drug arrests the following year and predicted that drug offenders can be deterred. Despite these crime control benefits results also suggested that the enforcement of banishment comes at a cost. First, a significant amount of banned individuals are not deterred. Second, while trespass enforcement is used in communities other than public housing, the issuing of bans is concentrated only within public housing communities and bans are predominantly issued to African-American males. Finally, results found that residents are not likely to find them effective if they think they are policing too much or policing too little. Future directions and implications are discussed given the dynamic between the crime control benefits of banishment and its social consequences.