Towards an understanding of the carbon isotopic changes across the Toarcian oceanic anoxic event

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 2005.Includes bibliographical references (p. 63-68).A combination of bulk carbon, biomarker and compound specific isotopic analyses were used in order to investigate the changes which accompanied the deposition of black shales during the upper tenuicostatum and lower falciferum zones of the Toarcian (early Jurassic, 183 Ma) ocean anoxic event (OAE). In this study, we reveal that apparent negative isotopic excursions in bulk organic and carbonate carbon were the result of compositional changes of organic matter and diagenesis, respectively. Organic petrology and Rock-Eval pyrolysis of organic matter from the Jet Rock, Hawsker Bottoms, Yorkshire, England, show that the upper tenuicostatum zone contains very large amounts of terrigenous debris. A careful review of the carbonate carbon record, as reported in the literature, indicates that a large negative isotopic excursion in bulk carbonate is likely the result of diagenesis, rather than reflective of seawater isotopic conditions. Biomarker distributions and isotopic composition of primary production biomarkers show little variation during the largest changes in the bulk records. Biomarker source indicators vary little throughout the section, indicating little change in biota or redox structure of the water column during this widespread deposition of black shales. Isotopic compositions of algal short chain n-alkanes, pristane and phytane also remain steady across the section.(cont.) Long chain n-alkanes, biornarkers for higher plants, also do not change during the event. Isorenieratane, a biomarker for green sulphur bacteria and an indicator of photic zone euxinia, however, show a strong peak in concentration coincident with the maximum abundance of organic carbon. Because we have found no evidence for significant isotopic variation on land or in the ocean, we must infer that there were no major redistributions of carbon in the ocean-atmosphere system during the Toarcian OAE. Therefore, oceanic overturn or large input of methane are not plausible explanations for this event. This deposition of black shales was a result of periodic episodic euxinia, which resulted in the increased preservation of organic matter. We believe that this event was not a large, one-time occurrence, but a characteristic response to paleogeography and oceanic circulation patterns of the Mesozoic.by Alison Margaret Cohen.S.M

Socioeconomic disadvantage in childhood as a predictor of excessive gestational weight gain and obesity in midlife adulthood.

BackgroundLower childhood socioeconomic position is associated with greater risk of adult obesity among women, but not men. Pregnancy-related weight changes may contribute to this gender difference. The objectives of this study were to determine the associations between: 1. childhood socioeconomic disadvantage and midlife obesity; 2. excessive gestational weight gain (GWG) and midlife obesity; and 3. childhood socioeconomic disadvantage and excessive GWG, among a representative sample of childbearing women.MethodsWe constructed marginal structural models for seven measures of childhood socioeconomic position for 4780 parous women in the United States, using National Longitudinal Survey of Youth (1979-2010) data. Institute of Medicine definitions were used for excessive GWG; body mass index ≥30 at age 40 defined midlife obesity. Analyses were separated by race/ethnicity. Additionally, we estimated controlled direct effects of childhood socioeconomic disadvantage on midlife obesity under a condition of never gaining excessively in pregnancy.ResultsLow parental education, but not other measures of childhood disadvantage, was associated with greater midlife obesity among non-black non-Hispanic women. Among black and Hispanic mothers, childhood socioeconomic disadvantage was not consistently associated with midlife obesity. Excessive GWG was associated with greater midlife obesity in all racial/ethnic groups. Childhood socioeconomic disadvantage was not statistically significantly associated with excessive GWG in any group. Controlled direct effects were not consistently weaker than total effects.ConclusionsChildhood socioeconomic disadvantage was associated with adult obesity, but not with excessive gestational weight gain, and only for certain disadvantage measures among non-black non-Hispanic mothers. Prevention of excessive GWG may benefit all groups through reducing obesity, but excessive GWG does not appear to serve as a mediator between childhood socioeconomic position and adult obesity in women

Evaluation Design and Technical Assistance Opportunities: Early Findings From the Beacon Community Program Evaluation Teams

Examines study designs, evaluation approaches, outcome measures, data sources, challenges, and technical assistance needs among sites in a project under the American Recovery and Reinvestment Act to strengthen health information technology capabilities

The Role of Capstone Workshops in Connecting Environmental Policy Masters Students to Employer Communities

The Master of Public Administration in Environmental Science and Policy (MPA ESP) began in 2002 to train sophisticated public managers and policymakers who apply innovative, systems-based thinking to environmental issues. Students in the MPA in Environmental Science and Policy program complete a total of 54 credits over the course of an intensive twelve months. The program’s objective is to provide students with the analytic, communication, and work skills required to be problem-solving earth systems professionals. Graduates are prepared for professional careers in the roles of analyst, manager, and translator of scientific knowledge. The program’s curriculum combines in-depth understanding of the issues of environmental sustainability policy with the traditional analytic and conceptual skills of a master of public administration (MPA) program. Two fundamental insights shape this master’s program: the realization that institutional, social, and economic processes interconnect to both sustain and endanger the planet and the need for professionals who can maintain the health of this interconnected system. Only by combining an understanding of earth systems issues with management strategies will it be possible to cope with the threats to planetary sustainability

Climate Change 2011: A Status Report on US Policy

A growing partisan divide in Congress stalled almost all new federal climate policy in 2011. The divide frustrated efforts to pass a cap-and-trade carbon permitting system, spawned a battle between the US Environmental Protection Agency (EPA) and Congress, pushed most substantive climate change policy down to the municipal level and hindered US ability to effectively negotiate an international climate agreement. Amid the federal partisan wrangling, US cities have enacted far-sighted climate policy initiatives, and the growing cost of fossil fuels has stimulated investment in renewable energy, edging the country closer to commercially viable alternatives to fossil fuels. These trends could help provide an alternate route to climate mitigation, even without international treaties or national legislation. But the inevitable shift from fossil fuels to renewable energy sources would be greatly hastened by federal action to tax carbon dioxide emissions and use the revenue generate! d to support alternative energy technologies. That action is extremely unlikely to occur unless climate change comes to be seen in the United States as a practical, rather than ideological, issue

Measuring the Relational Aspects of Civic Engagement and Action

Civic leaders who are highly and effectively engaged often have strong relationships with key stakeholders across institutions and communities. The prevalence and nature of these relationships is not known among those with more typical levels of civic engagement. Via survey data of a random sample of residents of two neighboring French towns, we find that people perceive their neighbors to be, on average, more engaged than they perceive to be themselves, and that few individuals can provide specific action steps for how they would tackle social issues in their community. These results suggest that teaching civic action skills, including how to identify key decision makers as possible allies, is important for civic educators

Aphasia simulation: A perspective from the student and standardized patient

The aim of the current study was to examine student ability, student and standardized patient perceptions of competency, and student perceptions of effectiveness of simulation methodology for conducting language screenings on individuals with aphasia. Graduate students enrolled in a mandatory course on acquired language disorders (n = 36) completed a variety of simulated learning experiences using videos, high-fidelity manikins, and standardized patients, in preparing them for clinical practice with persons with aphasia. 5-point Likert scales and open-ended survey questions relating to student and standardized patients’ perceptions were administered. Results demonstrated a strong positive perception that simulation promotes student understanding of assessment procedures and aids in the development of clinical judgment. Data also illuminate that certain skills may be slower to emerge and require greater experience and supervisory feedback, for example, problem-solving difficult moments. There was an overall positive response to the use of simulation methodology to build skills in screening patients with PWA. Students’ perceptions matched that of the standardized patients, and students excelled in the final summative skill activity. Keywords: aphasia; simulated learning; academic education; clinical educatio