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Great Salt Lake ooids: insights into rate of formation, potential as paleoenvironmental archives, and biogenicity
No full text2019-05-10Ooids are laminated coated grains that are most commonly composed of calcium carbonate which precipitates around a nucleus. As accretionary structures, they have the potential to record a time series of hydrologic and geochemical change in marine and lacustrine environments. Ooids are common in carbonate environments throughout Earth’s history, but the mechanism by which they form remains unclear. In particular, the rate of ooid growth remains elusive in all but a few modern marine environments. Furthermore, modern marine ooids display tangentially-oriented aragonite crystals within their cortices, whereas many ancient ooids have radially-oriented cortices. Ooids are traditionally viewed as abiogenic precipitates, however the role of biology in ooid formation has recently been suggested because certain microbial metabolisms may either foster carbonate precipitation or dissolution by manipulating dissolved inorganic carbon and alkalinity. The following dissertation uses ooids from Great Salt Lake (GSL), Utah, a well-known site of primary radial ooids, to investigate ooid growth rate and age, the potential of ooids to resolve lacustrine hydrologic change, and the biogenicity of lacustrine ooids. ❧ We used ¹⁴C to establish a sequential chronology for ooids from GSL. Ooids from the coarse size fraction were sequentially dissolved and ¹⁴C ages were obtained for each dissolution step to create a time series of ooid growth. The results of the sequential dating indicate that the formation of coarse Great Salt Lake ooids began between 5800-6600 ± 60 ¹⁴C yr BP while their outer cortices are nearly modern. Sequentially dated ooids from Antelope Island (southern part of Lake) record a nearly linear growth history with linear growth rates of ∼0.01 – 0.015 µm/yr, whereas ooids from Spiral Jetty (NE part of Lake) record somewhat faster growth between ∼6000 and 4000 years ago (0.03 – 0.06 µm/yr) followed by a slower growth history for the remainder of their lifespan (0.003 – 0.008 µm/yr). The lifespan of Great Salt Lake radial aragonitic ooids ranges is two and six times longer than those from modern marine environments, and thus provides a unique end member for understanding the mechanisms behind radial ooid formation. The antiquity of the ooids would suggest that geochemical parameters measured from bulk ooid dissolution would integrate over ∼6000 years and thus do not represent geochemical snapshots in time as some previous studies suggest. ❧ Lake level indicators are sparse in GSL between ∼10,000 ybp and the onset of historical times, so the Holocene lake variation is somewhat poorly resolved. We evaluate the ¹⁴C age and stable carbon isotope composition of ooids that grew in the lake over the last 7,000 years. Since δ¹³C and δ¹⁸O covary in closed basin lakes, changes in the δ¹³C through time can be interpreted to represent changes in lake volume if other assumptions we make hold true. Ooids were sequentially dissolved to create a paired radiocarbon chronology and δ¹³C profile with depth in the ooid. Petrographic analysis reveals that, for the majority of ooids, the initial precipitation upon the nucleus is represented by a comparatively large aragonite crystal ray texture, followed by alternations of finely crystalline radial aragonite and thin radial-concentric layers. Net growth rates derived from radiocarbon ages indicate the large crystal ray fabric corresponds to 7498 to 2073 cal yr BP with δ¹³C between 4.4±0.15 and 4.8±0.15 ‰, likely indicating a relatively stable lake level. The alternating fabric precipitated between 2073 cal yr BP to present, and the δ¹³C values of ooids trending toward lighter values (from ∼4.5‰ to 3.7‰), suggests a largely transgressive phase in GSL. The youngest inorganic carbon sample from north arm ooids falls off this trend as it has a significantly heavier δ¹³C of 5.6±0.15‰. Modern dissolved inorganic carbon from north arm lake water indicates aragonite precipitating today would have δ¹³C values between 9.1±0.55‰ to 9.8±0.75‰, therefore the young heavy inorganic carbon of north arm ooids likely suggests that ooid formation has occurred after the construction of the railroad causeway in 1959, which isolated the north arm from the riverine-influenced southern portion and thus left the reservoir to generate an enriched δ¹³C pool, representing the first robust evidence that ooid formation has occurred in modern times. Furthermore, the entire chronology of GSL ooids from both sample sites record over 2‰ variability in δ¹³C over several thousand years, which calls into question the utility of bulk geochemical analyses from accretionary structures such as ooids in dynamic systems such as closed-basin lakes. ❧ To investigate the biogenicity of ooids in GSL, we evaluated the microbial community of ooids from the southern arm of GSL and the brine shrimp (Artemia) pellets upon which they commonly form. The small subunit rRNA analysis revealed ooids and Artemia pellets have similar microbial assemblages dominated in Bacteroidetes, Alphaproteobacteria, Deltaproteobacteria, and Gammaproteobacteria. The striking similarity between the microbial communities of GSL ooids and brine shrimp gut microbiota suggests relict DNA residing in oolitic nuclei may be an important source of DNA in microbial community analysis of ooids and other accretionary structures. The calcium carbonate saturation state of GSL is supersaturated with respect to aragonite, though it ranges from 100% to 250% saturation seasonally. Calcification rates of GSL ooids are several orders of magnitude lower than experimental precipitation of aragonite, suggesting aragonite may be precipitating in GSL just above saturation, conditions that do not necessitate the geochemical manipulation of microbiota to achieve in this system
Resilience by anticipating change: simple and robust decision making for coastal adaptation planners, communities and elected officials
No full text2019-05-10Management of the coastal zone under climate change and deep uncertainty requires robust, flexible and adaptive policy-making based on the effectiveness of the adaptation measures against always changing conditions. This dissertation presents an application of dynamic adaptation pathways, triggered by tipping points, turning points, and other environmental and socioeconomic indicators to increase the resiliency of the Carmen-Pajonal-Machona lacunae system against Climate Change, erosion, salinization, pollution, and against impacts of future development. This application may be expanded to the Gulf of Mexico including the US and other significant environments in the Meso-America corridor in more than seven countries
Civic engagement of Teach For America alumni in Los Angeles
No full text2019-04-29The purpose of this study was to understand the corps member experience of Teach For America (TFA) alumni and how it motivated their political and civic engagement in the greater Los Angeles area. This study used Bronfenbrenner’s Ecological Systems Theory and the TFA Conceptual Framework to understand alumni decisions to serve in public office. The study used a qualitative case study methodology using a semi-structured interview protocol and a document analysis protocol. The seven participants, TFA alumni currently serving in public office, included a municipal leader, school board members, and neighborhood council members. The results of this study revealed several key components of the TFA corps member experience, as well as trends in personal backgrounds and beliefs, that impacted their decision to seek public office. Additionally, this study revealed parts of the TFA experience and network that assisted alumni in successfully seeking office, obtaining office, and holding office. Previous research studies were limited, so this study played an important role in expanding the literature on TFA and its impact on policy and civic engagement. Finally, the findings will inform TFA-provided placement and professional development supports for corps members. It will also inform campaign supports and training opportunities provided by Leadership for Educational Equity (LEE) for TFA alumni, given that both organizations collaborate and seek to maximize TFA alumni impact on educational inequity
Antibiotic resistance in a large ICU cohort: 1995-2002
No full text2019-05-13Antibiotic use has been implicated in development of antibiotic resistance by microbiological, animal, and epidemiological research. However, whether antibiotics eliminated through the microbe-rich gut may confer greater risk of resistance than antibiotics eliminated through the kidneys has not been previously investigated. We addressed this novel hypothesis using data from patients admitted to the Intensive Care Unit (ICU) of the Los Angeles County + University of Southern California Medical Center (LAC+USC MC) between 1993 and 2003. Specifically, we collected data describing antibiotic use and antibiotic resistance of organisms cultured from blood of patients with hospital-acquired bloodstream infections (HA-BSI) and antibiotic administration records of patients admitted to the ICU. We combined detailed demographic and treatment data on the ICU patients to create two analytic cohorts: a health and policy cohort representative of ICU patients (described in Chapters 2 and 3) and a clinically relevant cohort of patients among whom HA-BSI was diagnosed following administration of antibiotics (described in Chapter 4). Analyses of the public health cohort were designed to describe the cohort, to understand trends of antibiotic use and organisms identified from blood cultures among all patients and those from whom ESKAPE organisms were cultured, and to estimate both associations describing antibiotic-organism specific resistance and antibiotic exposure-attributable fractions. Analyses of the clinically relevant cohort addressed whether route of elimination of antibiotics was associated with subsequent drug resistance and mortality. ❧ In Chapter 2, we describe sources of data received from the LAC+USC for the study, as well as definitions, assumptions, and procedures that were used to generate the overall cohort of ICU patients. Briefly, data were extracted from clinical records and loaded as Microsoft ACCESS databases; subsequently converted into Microsoft Excel Workbooks for clinical review; and imported into SAS as sas7bdat files for data cleaning, manipulation, and assembly. The independent variable, route of elimination of each antibiotic administered, was classified using medication administration data from patients in the ICU. The primary dependent variable was drug resistance of bacteria identified from blood cultures which was based on antibiotic susceptibility assessment of organisms. Additional outcome variables, including death, as well as demographic characteristics, and select comorbidities were derived for all patients in the ICU. The final analytic dataset included 11,576 patients, of whom 9,541 were administered at least one antibiotic and 2,035 had no antibiotic use. A total of 10,497 patients had no eligible blood cultures. Of those with a positive blood culture (N=1,079), 566 were non-resistant, 398 multi-drug resistant, and 115 extensive-drug resistant. ❧ In Chapter 3 we report on analyses of the public health and policy cohort, wherein we estimated associations between route of antibiotic elimination as well as resistance and proportion of drug resistant HA-BSI organisms attributable to each antibiotic type. We assessed drug resistance (no resistance, multi-drug resistance, extensive-drug resistance) of organisms identified in subsequent HA-BSI in relation to route of elimination of antibiotic administered (none, kidneys, liver). Compared to patients administered no antibiotic, the odds of developing multi-drug resistance was 1.82(95% CI: 1.11-2.97, p=0.0169)- versus 2.99(95% CI: 1.84-4.85, p<0.0001)-times higher in those administered antibiotics eliminated through the kidneys and liver, respectively; odds of developing extensive-drug resistance was 3.46(95% CI: 0.82-14.68, p=0.0923)- versus 7.60(95% CI: 1.84-31.41, p=0.0051)-times higher in these groups. Moreover, estimated resistance attributable to antibiotics was 41.7% versus 72.8% among patients who received antibiotics eliminated through the kidneys and liver, respectively. ❧ In Chapter 4, we describe an extreme phenotype case-case study (N=693) nested within the retrospective cohort described above (N=11,563). Patients with a HA-BSI who were treated with at least one antibiotic were classified according to the route of antibiotic elimination (liver or kidneys) and according to drug resistance (none, multi-drug, or extensive-drug resistance). We assessed the association between the route of elimination and both resistance and mortality using multinomial regression and Cox proportional hazards model, respectively. Patients administered any antibiotic eliminated through the liver had increased odds of a subsequent drug-resistant BSI of any kind (OR=1.44, p=0.0390) and increased risk of death (HRR=1.86, p=0.007). ❧ We identified a pattern of drug resistance associated with antibiotic use, in both the overall cohort of ICU patients (N=11,576) and a clinically relevant cohort of patients stringently selected for antibiotic use and positive blood cultures (N=693). Both multi-drug and extensive-drug resistance were more common in patients who had been administered any form of antibiotics, but associations had greatest magnitude for patients with antibiotics eliminated at least partially through the liver
Confession of K-pop fanboys: what fans learn about societal definitions of masculinity, stigmas and self-identities through discovering Korean pop music
No full text2019-06-07K-Pop has always been seen as a passing fad or a one-viral sensation that a lot of people don’t take seriously. Think PSY of ‘Gangnam Style’. But in the last few years, the popularity of K-Pop has seeped into the mainstream consciousness stronger than ever. With the arrival of the seven-member boy band, BTS and other groups like BLACKPINK, NCT 127 and MONSTA X in the U.S., K-Pop has slowly become a household term. However, the South Korean music industry still suffers from certain stigmas, concerning the feminine-looking male performers that seem to defy traditional masculinity norms in the West, along with the quality of the music that skeptics deem ‘manufactured’. Another stereotype of K-Pop is that it is dominated by young female fans, but the rising presence of male followers show that the music is becoming more inclusive to both gender. In this story, fanboys opened up their love for K-Pop, the problems they encounter for liking the music and how boy bands, like BTS, have helped them understand the concept of masculinity far better
Early life air pollution exposure, gestational diabetes mellitus, and autism spectrum disorder
No full text2019-06-17In the United States (U.S.), autism spectrum disorder (ASD) prevalence has increased over several decades among young children, disproportionately affecting more boys than girls. The effects of air pollution and gestational diabetes mellitus (GDM) have been hypothesized to increase the risk of ASD through common biologic mechanisms including oxidative stress and inflammation that could alter fetal brain development. Particulate matter <2.5 in aerodynamic diameter (PM₂.₅) has shown relatively consistent adverse effects on ASD; however, associations between air pollution and GDM have been inconsistent. Because GDM is also hypothesized to be a risk factor for ASD, it is important to evaluate these associations together, which no studies to date have done for ASD. This dissertation aimed to address this critical gap in the current literature on environmental epidemiology of ASD by evaluating the role of air pollution in the etiology of GDM and ASD. Based on animal studies showing male-specific effects of particles on autism-like behaviors, results suggested that boys may be at a higher risk for ASD than girls if exposed to higher first trimester PM₂.₅ exposure. In examining the associations between pollutants and GDM, maternal exposure to nitrogen dioxide before conception was associated with increased risk of GDM. Furthermore, GDM diagnosed earlier in pregnancy may increase children’s susceptibility to prenatal and early life ozone-associated ASD risk. Further studies are needed to better understand the biological basis and timing of susceptibility during neurodevelopment. Air pollution and GDM are common risk factors amenable to intervention targeting public policy and behavior
The adolescent learner's perspective on intensive literacy intervention curriculum
No full text2019-06-18Struggling adolescent readers and writers who have a history of underachievement and frustration with their lack of literacy attainment are especially prone to disengagement and motivational issues (Gilson et al., 2018; Lovett et al., 2012). This qualitative study employs self-determination theory as a framework for understanding how the motivational needs of struggling middle school literacy learners are met through their participation in an intensive literacy intervention program, Language! Live (Niemec & Ryan, 2009). The researcher interviewed 11 middle school students and conducted a single focus group session to allow the struggling adolescent literacy learners in this study to describe their experiences in their own words. Data collected during the interviews and focus group discussion was transcribed and analyzed consistent with Creswell’s (2014) process of thematic content analysis and included both a deductive and an inductive approach. The themes that emerged as a result of this process revealed how the students’ motivational needs for autonomy, competence, and relatedness are met through structures, strategies, and tools embedded in the design of the Language! Live program. The findings of this study can assist researchers and educators of struggling adolescent literacy learners in understanding how to better design and implement intensive literacy intervention programs in ways that promote students’ motivational needs and fosters their engagement in learning
Advancing collaboration between Joint Terrorism Task Forces and fusion centers
No full text2019-06-04The purpose of this project was to evaluate fusion center and Joint Terrorism Task Force (JTTF) relationship-enhancing strengths and resource needs at three United States fusion centers. The larger problem of practice was that of sporadic relationship dysfunction between fusion centers and their partner JTTFs. To obtain data, the researcher conducted a literature review, interviewed 10 fusion center employees, collected documents, and made observations. A modified gap analysis framework based on possible knowledge, motivation, and organizational influences at the participants’ fusion centers helped focus the study. The strongest findings were related to knowledge of how to add value to the JTTF mission, positive emotions, cultural models of trust and collaboration, and employees having the appropriate permissions to access a variety of systems. Additional findings were on formal socialization techniques, attributions, and socialization opportunities potentially created by the fusion center. Upon consideration of the findings, the researcher made recommendations potentially useful to fusion centers seeking to strengthen or maintain their relationship with the JTTF. The primary recommendations involve fusion center leadership providing knowledge job aids, attributional retraining, and socialization opportunities. Secondary recommendations were for leadership to support employee efforts, encourage positive emotions, reinforce models of trust and collaboration, and ensure employees have appropriate permissions to access a variety of systems
Multi-armed bandit problems with learned rewards
No full text2019-07-08Suppose there are K arms of a slot machine, with arm i having a deterministic value v_i, i = 1, 2, …, K. The values v_i are assumed to be independently generated from a common known distribution F, and are initially unknown to the player. In each game, the player chooses an arm to play, learns the arm’s value and receives a reward equal to this value. The objective is to find a policy that maximizes the expected sum of rewards in N games, where N is a random variable following a known distribution. ❧ We model the preceding problem as a stochastic dynamic programming problem, with the state being (n, x, k), where n is the game about to be played, x is the value of the best old arm, and k is the number of remaining new arms. We show that the optimal policy is a threshold policy, meaning that there are threshold values c(n, k) such that the optimal action in state (n, x, k) is to play x if x >= c(n, k) and play a new arm if x < c(n, k). We also show that c(n, k) increases in k. When the horizon N has increasing failure rate (IFR), we show that c(n, k) decreases in n, and obtain their values using a one-stage lookahead procedure. In addition, we derive an expression for the maximum expected sum of rewards, and propose efficient simulation algorithms when that quantity is difficult to compute analytically. The preceding results are also shown when there are infinitely many arms. ❧ When N is not IFR, N is unknown, or F has unknown parameters, we use the preceding results to construct high-performance and easy-to-implement heuristic policies, and evaluate their performances using simulation. ❧ We also consider a variation of the problem where the player is only allowed to play either a new arm or the arm used in the last game. Supposing that F is known and the distribution of N is known, we show that the optimal policy is a threshold policy and the optimal threshold values c(n, k) increase in k. In addition, when N is IFR, we show that the optimal policy is a threshold stopping policy
Let there be LIGHT: TNFSF14 immunomodulating properties for cancer immunotherapy
No full text2019-07-15The continuing need for novel cancer therapies has turned its gaze towards the tumor necrosis factor superfamily member 14 (TNFSF 14), also known as LIGHT. LIGHT (homologous to lymphotoxins, exhibits inducible expression and competes with HSV glycoprotein D for HVEM, a receptor expressed by T cells) is a pro-inflammatory costimulatory protein expressed on immature dendritic cells, activated natural killer cells, and activated T cells. By eliciting robust anti-tumor responses via interferon γ mediated apoptosis, tumor angiogenic vascular normalization, high endothelial venule formation, tertiary lymphoid structure formation, and immune activation, LIGHT has piqued the interest of researchers over the past two decades. By delivering LIGHT properly to tumors via gene transfer, Adenovirus vectors, adoptive transfer, antibodies, or vascular targeting peptides, LIGHT has shown promise as a new candidate in cancer immunotherapy. This review will further clarify the diverse effects, deliveries, and immunotherapeutic combinations LIGHT has to offer