Coseismic deformation observed with radar interferometry: Great earthquakes and atmospheric noise

Spatially dense maps of coseismic deformation derived from Interferometric Synthetic Aperture Radar (InSAR) datasets result in valuable constraints on earthquake processes. The recent increase in the quantity of observations of coseismic deformation facilitates the examination of signals in many tectonic environments associated with earthquakes of varying magnitude. Efforts to place robust constraints on the evolution of the crustal stress field following great earthquakes often rely on knowledge of the earthquake location, the fault geometry, and the distribution of slip along the fault plane. Well-characterized uncertainties and biases strengthen the quality of inferred earthquake source parameters, particularly when the associated ground displacement signals are near the detection limit. Well-preserved geomorphic records of earthquakes offer additional insight into the mechanical behavior of the shallow crust and the kinematics of plate boundary systems. Together, geodetic and geologic observations of crustal deformation offer insight into the processes that drive seismic cycle deformation over a range of timescales. In this thesis, I examine several challenges associated with the inversion of earthquake source parameters from SAR data. Variations in atmospheric humidity, temperature, and pressure at the timing of SAR acquisitions result in spatially correlated phase delays that are challenging to distinguish from signals of real ground deformation. I characterize the impact of atmospheric noise on inferred earthquake source parameters following elevation-dependent atmospheric corrections. I analyze the spatial and temporal variations in the statistics of atmospheric noise from both reanalysis weather models and InSAR data itself. Using statistics that reflect the spatial heterogeneity of atmospheric characteristics, I examine parameter errors for several synthetic cases of fault slip on a basin-bounding normal fault. I show a decrease in uncertainty in fault geometry and kinematics following the application of atmospheric corrections to an event spanned by real InSAR data, the 1992 M5.6 Little Skull Mountain, Nevada, earthquake. Finally, I discuss how the derived workflow could be applied to other tectonic problems, such as solving for interseismic strain accumulation rates in a subduction zone environment. I also study the evolution of the crustal stress field in the South American plate following two recent great earthquakes along the Nazca- South America subduction zone. I show that the 2010 Mw 8.8 Maule, Chile, earthquake very likely triggered several moderate magnitude earthquakes in the Andean volcanic arc and backarc. This suggests that great earthquakes modulate the crustal stress field outside of the immediate aftershock zone and that far-field faults may pose a heightened hazard following large subduction earthquakes. The 2014 Mw 8.1 Pisagua, Chile, earthquake reopened ancient surface cracks that have been preserved in the hyperarid forearc setting of northern Chile for thousands of earthquake cycles. The orientation of cracks reopened in this event reflects the static and likely dynamic stresses generated by the recent earthquake. Coseismic cracks serve as a reliable marker of permanent earthquake deformation and plate boundary behavior persistent over the million-year timescale. This work on great earthquakes suggests that InSAR observations can play a crucial role in furthering our understanding of the crustal mechanics that drive seismic cycle processes in subduction zones

Examining the Relationship between Intramural Sports Participation and Sense of Community among College Students

The purpose of this study was to determine if there were statistically significant relationships between intramural sports participation and sense of community among college students. A convenience sample was used, comprised of intramural sports participants from a university in the southeastern United States. Participants completed a questionnaire consisting of demographic questions and the Sense of Community Index-2 (SCI-2) (Chavis, Lee & Acosta, 2008) to rate their level of sense of community experienced through participation in intramural sports. The SCI-2 consists of four subscales, pertaining to the contributing elements of sense of community: membership, influence, integration and fulfillment of needs, and shared emotional connection (McMillan & Chavis, 1986). Questionnaires were distributed once and administered online, and all responses were confidential. Multiple regressions, analysis of variance and t-tests were used test for significant relationships between sense of community and respondents' (a) length of intramural sports participation and (b) frequency of intramural sports participation. Results indicated that increased length of participation was strongly associated with a greater sense of community among participants. Study findings could be used to develop effective marketing plans to attract student participants, while also providing the framework that programmers need to support their intramural program's existence to campus administrators.  M.S

Glacier dynamics: Using velocity and temperature profiles to understand climate fluctuations

From glaciers, scientists can understand modern climate in the context of paleoclimate and develop tools to make sound predictions about the future health of glaciers that serve as important water or power sources. Because glaciers are complex dynamical systems, they are challenging to study, but particular topics are enlightening for understanding the general dynamics of glaciers. Topics in this paper include mechanics of materials, glacier anatomy, flow on the atomic and glacier scale, glacier temperature profiles, the formation of crevasses and mass balance. The Chacaltaya glacier in Bolivia serves as a case example, because this glacier has experienced a negative mass balance over the past 70 years and therefore gives opportunity to discuss the glacier dynamics and the implications to human populations of a melting glacier

Kinematic modeling of deformation in the Troodos ophiolite, Cyprus

The Troodos ophiolite in Cyprus is an ideal location to study deformation at a ridge- transform intersection. The ophiolite exposes both the fossil Arakapas transform fault and the Solea graben, an extinct spreading ridge. I analyzed paleomagnetic data from gabbros, which show vertical axis rotations that vary with position relative to the Arakapas fault belt and the Solea graben. This study characterizes the deformation between the Arakapas fault and the Solea graben based on my paleomagnetic rotation data and sheeted dike orientations by constructing numerical models. I test seven two-dimensional kinematic models, each of which represents heterogenous simple shear, to better constrain the spatial distribution of deformation due to motion along the Arakapas fault belt. I estimate that least 40 km of displacement has been accommodated along the transform fault and that 90% of this displacement is accommodated within 1.5 km of the fault. These types of quantitative estimates have not been made before for the Troodos ophiolite

Examining the Relationship between Intramural Sports Participation and Sense of Community among College Students

The purpose of this study was to determine if there were statistically significant relationships between intramural sports participation and sense of community among college students. A convenience sample was used comprised of intramural sports participants from a university in the southeastern United States. Participants completed a questionnaire consisting of demographic questions and the Sense of Community Index-2 (SCI-2) (Chavis Lee & Acosta 2008) to rate their level of sense of community experienced through participation in intramural sports. The SCI-2 consists of four subscales pertaining to the contributing elements of sense of community: membership influence integration and fulfillment of needs and shared emotional connection (McMillan & Chavis 1986). Questionnaires were distributed once and administered online and all responses were confidential. Multiple regressions analysis of variance and t-tests were used test for significant relationships between sense of community and respondents' (a) length of intramural sports participation and (b) frequency of intramural sports participation. Results indicated that increased length of participation was strongly associated with a greater sense of community among participants. Study findings could be used to develop effective marketing plans to attract student participants while also providing the framework that programmers need to support their intramural program's existence to campus administrators.

Cigarette Smoke–induced Oxidative/Nitrosative Stress Impairs VEGF- and Fluid Shear Stress–Mediated Signaling in Endothelial Cells

VEGF receptor 2 (VEGFR2), a tyrosine kinase receptor, is activated by VEGF and fluid shear stress (FSS), and its downstream signaling is important in the regulation of endothelial functions, such as cell migration, endothelium-dependent relaxation, and angiogenesis. Cigarette smoke (CS) is known to cause oxidative/nitrosative stress, leading to modifications of tyrosine kinase receptors and impaired downstream signaling. We hypothesized that CS-induced oxidative/nitrosative stress impairs VEGF- and FSS-mediated VEGFR2 activation, leading to endothelial dysfunction. Human lung microvascular endothelial cells and human umbilical vein endothelial cells were treated with different concentrations of cigarette smoke extract (CSE) to investigate the VEGF- or FSS-mediated VEGFR2 phosphorylation and its downstream signaling involved in endothelial function. CSE treatment impaired both VEGF- and FSS-mediated VEGFR2 phosphorylation, resulting in impaired endothelial nitric oxide synthase (eNOS) phosphorylation by Akt. CS-derived reactive oxygen/nitrogen species react with VEGFR2, rendering VEGFR2 inactive for its downstream signaling. Pretreatment with nitric oxide scavenger (PTIO), reactive oxygen species scavengers (combination of SOD with catalase), and N-acetyl-l-cysteine, significantly attenuated the CSE-induced impairment of VEGF-mediated Akt and eNOS phosphorylation. These findings suggest that CSE-induced oxidative/nitrosative stress impairs VEGF- and FSS-mediated endothelial cell function and has important implications in the pathogenesis of CS-induced pulmonary and cardiovascular diseases associated with endothelial dysfunction. Antioxid. Redox Signal. 12, 1355–1369

Coinfection with blood-stage plasmodium promotes systemic type I interferon production during pneumovirus infection but impairs inflammation and viral control in the lung

Acute lower respiratory tract infections (ALRTI) are the leading cause of global childhood mortality, with human respiratory syncytial virus (hRSV) being a major cause of viral ALRTI in young children worldwide. In sub-Saharan Africa, many young children experience severe illnesses due to hRSV or Plasmodium infection. Although the incidence of malaria in this region has decreased in recent years, there remains a significant opportunity for coinfection. Recent data show that febrile young children infected with Plasmodium are often concurrently infected with respiratory viral pathogens but are less likely to suffer from pneumonia than are non-Plasmodium-infected children. Here, we hypothesized that blood-stage Plasmodium infection modulates pulmonary inflammatory responses to a viral pathogen but does not aid its control in the lung. To test this, we established a novel coinfection model in which mice were simultaneously infected with pneumovirus of mice (PVM) (to model hRSV) and blood-stage Plasmodium chabaudi chabaudi AS (PcAS) parasites. We found that PcAS infection was unaffected by coinfection with PVM. In contrast, PVM-associated weight loss, pulmonary cytokine responses, and immune cell recruitment to the airways were substantially reduced by coinfection with PcAS. Importantly, PcAS coinfection facilitated greater viral dissemination throughout the lung. Although Plasmodium coinfection induced low levels of systemic interleukin-10 (IL-10), this regulatory cytokine played no role in the modulation of lung inflammation or viral dissemination. Instead, we found that Plasmodium coinfection drove an early systemic beta interferon (IFN-beta) response. Therefore, we propose that blood-stage Plasmodium coinfection may exacerbate viral dissemination and impair inflammation in the lung by dysregulating type I IFN-dependent responses to respiratory viruses

Risk Factors Associated with Incident Syphilis in a Cohort of High-Risk Men in Peru

Syphilis is concentrated among high-risk groups, but the epidemiology of syphilis reinfection is poorly understood. We characterized factors associated with syphilis incidence, including reinfection, in a high-risk cohort in Peru.Participants in the NIMH CPOL trial were assessed at baseline and 2 annual visits with HIV/STI testing and behavioral surveys. Participants diagnosed with syphilis also attended 4- and 9-month visits. All participants underwent syphilis testing with RPR screening and TPPA confirmation. Antibiotic treatment was provided according to CDC guidelines. Reinfection was defined as a 4-fold titer increase or recurrence of seroreactivity after successful treatment with subsequent negative RPR titers. The longitudinal analysis used a Possion generalized estimating equations model with backward selection of variables in the final model (criteria P <0.02).Of 2,709 participants, 191 (7.05%) were RPR-reactive (median 1:8, range 1:1-1:1024) with TPPA confirmation. There were 119 total cases of incident syphilis, which included both reinfection and first-time incident cases. In the bivariate analysis, the oldest 2 quartiles of age (incidence ratio (IR) 3.84; P <0.001 and IR 8.15; P <0.001) and being MSM/TW (IR 6.48; P <0.001) were associated with higher risk of incident syphilis infection. Of the sexual risk behaviors, older age of sexual debut (IR 12.53; P <0.001), not being in a stable partnership (IR 1.56, P = 0.035), higher number of sex partners (IR 3.01; P <0.001), unprotected sex in the past 3 months (IR 0.56; P = 0.003), HIV infection at baseline (IR 3.98; P <0.001) and incident HIV infection during the study period (IR 6.26; P = 0.003) were all associated with incident syphilis. In the multivariable analysis, older age group (adjusted incidence ratio (aIR) 6.18; P <0.001), men reporting having sex with a man (aIR 4.63; P <0.001), and incident HIV infection (aIR 4.48; P = 0.008) were significantly associated.We report a high rate of syphilis reinfection among high-risk men who have evidence of previous syphilis infection. Our findings highlight the close relationship between HIV incidence with both incident syphilis and syphilis reinfection. Further studies on syphilis reinfection are needed to understand patterns of syphilis reinfection and new strategies beyond periodic testing of high-risk individuals based on HIV status are needed