The biogeochemistry of microbial mats, stromatolites and the ancient biosphere

Stromatolites offer an unparalleled geologic record of early life, because they constitute the oldest and most abundant recognizable remains of microbial ecosystems. Microbial mats are living homologs of stromatolites; thus, the physiology of the microbiota as well as the processes which create those features of mats (e.g., biomarker organic compounds, elemental and stable isotopic compositions) which are preserved in the ancient record. Observations of the carbon isotopic composition (delta C-13) of stromatolites and microbial mats were made and are consistent with the hypothesis that atmospheric CO2 concentrations have declined by at least one to two orders of magnitude during the past 2.5 Ga. Whereas delta C-13 values of carbonate carbon average about 0 permil during both the early and mid-Proterozoic, the delta C-13 values of stromatolitic organic matter increase from an average of -35 between 2.0 and 2.6 Ga ago to an average of about -28 about 1.0 Ga ago. Modern microbial mats in hypersaline environments have delta C-13 values typically in the range of -5 to -9, relative to an inorganic bicarbonate source at 0 permil. Both microbial mats and pur cultures of cyanobacteria grown in waters in near equilibrium with current atmospheric CO2 levels exhibit minimal discrimination against C-13. In contrast, hot spring cyanobacterial mats or cyanobacterial cultures grown under higher CO2 levels exhibit substantially greater discrimination. If care is taken to compare modern mats with stromatolites from comparable environments, it might be possible to estimate ancient levels of atmospheric CO2. In modern microbial mats, a tight coupling exists between photosynthetic organic carbon production and subsequent carbon oxidation, mostly by sulfate reduction. The rate of one process fuels a high rate of the other, with much of the sulfate reduction occurring within the same depth interval as oxygenic photosynthesis. Other aspects of this study are presented

Prediction of transonic flutter for a supercritical wing by modified strip analysis and comparison with experiment

Use of a supercritical airfoil can adversely affect wing flutter speeds in the transonic range. As adequate theories for three dimensional unsteady transonic flow are not yet available, the modified strip analysis was used to predict the transonic flutter boundary for the supercritical wing. The steady state spanwise distributions of section lift curve slope and aerodynamic center, required as input for the flutter calculations, were obtained from pressure distributions. The calculated flutter boundary is in agreement with experiment in the subsonic range. In the transonic range, a transonic bucket is calculated which closely resembles the experimental one with regard to both shape and depth, but it occurs at about 0.04 Mach number lower than the experimental one

From the Ground Up: Indigenizing Medical Humanities and Narrative Medicine

Scholars in the emerging academic field of Medical Humanities (MH) argue that the MH can nurture students’ understanding of personal values, empathy, narrative integrity and cultural humility. MH programs, thus, include disciplinary diversity (offering courses in literature, cultural studies, visual arts, history of medicine, bioethics, etc.) but often do not consider the importance of diversity among the faculty that build and sustain the program. As we move from developing and teaching MH courses into an era of developing and implementing MH programs, we are called to address critical gaps in the conceptualization and realization of MH programs. In this reflective essay, we open up dialogue about the value of faculty diversity with the purpose of helping shape the vision and values of other developing MH programs. We share our experiences, as Indigenous scholars and educators, in the creation and expansion of a MH program at a mid-western state university. By sharing how we brought Indigenous values and perspectives to our roles as founding Director of the MH program and members of the MH executive committee, we tell the story of how our Indigenous worldviews are embodied in practices of narrative medicine that help bring us into wholeness as individuals and as an institution. In doing so, we establish the value of including faculty from diverse backgrounds in MH programs, give examples of how we incorporated Indigenous peoples\u27 ways of knowing, being and doing in our MH program and make recommendations for developing MH programs

Isotopic composition of Murchison organic compounds: Intramolecular carbon isotope fractionation of acetic acid. Simulation studies of cosmochemical organic syntheses

Recently, in our laboratories, samples of Murchison acetic acid were decarboxylated successfully and the carbon isotopic composition was measured for the methane released by this procedure. These analyses showed significant differences in C-13/C-12 ratios for the methyl and carboxyl carbons of the acetic acid molecule, strongly suggesting that more than one carbon source may be involved in the synthesis of the Murchison organic compounds. On the basis of this finding, laboratory model systems simulating cosmochemical synthesis are being studied, especially those processes capable of involving two or more starting carbon sources

Subsonic aerodynamic and flutter characteristics of several wings calculated by the SOUSSA P1.1 panel method

The SOUSSA (steady, oscillatory, and unsteady subsonic and supersonic aerodynamics) program is the computational implementation of a general potential flow analysis (by the Green's function method) that can generate pressure distributions on complete aircraft having arbitrary shapes, motions and deformations. Some applications of the initial release version of this program to several wings in steady and oscillatory motion, including flutter are presented. The results are validated by comparisons with other calculations and experiments. Experiences in using the program as well as some recent improvements are described

La prédiction des contacts avec le tribunal de la jeunesse : utilisation de l’évaluation du comportement par les pairs au début de l’école primaire

This study sets out to verify to what extent the evaluations of the behaviour of children by their peers in first year primary school make it possible to predict those who will eventually end up with an open record at the Juvenile Court. During their first year at school the children are classified according to the following categories : aggressive, socially withdrawn, aggressive-withdrawn, neither aggressive/nor withdrawn (contrast). A total of 992 subjects (493 girls and 499 boys) were evaluated at two different times during the study. The results indicate that the “aggressive-withdrawn” subjects, among the girls, are more likely to have an open record at the Court during the 7 or 8 years after having been evaluated in first year primary school. These findings may indicate that the girls whose behaviour is aberrant are more easily identified by their peers, given the fact that they generally have fewer problems of adaptation than the boys during their first year of school

Cross-cultural differences in temperament: Comparing paternal ratings of US and Dutch infants

This study conducted longitudinal comparisons of US and Dutch paternal ratings of temperament, measured via the Infant Behaviour Questionnaire-Revised, at 4 months (US n = 99; Dutch n = 127) and 12 months (US n = 66; Dutch n = 112) of age. US fathers rated their infant higher in the broad temperament trait Surgency, and its subscales vocal reactivity, high-intensity pleasure, and activity level. US fathers also rated their infants higher in negative emotionality, and its subscales of sadness, distress to limitations, and fear. Dutch infants received higher ratings in falling reactivity. Though the cultures did not differ in ratings of Orienting/regulatory capacity, US infants were higher on the subscale duration of orienting, and lower in soothability. Significant culture-by-age and culture-by-gender interactions were also noted. Overall, results are largely consistent with those reported for Dutch mothers and speak to considerable differences in early temperament development between cultures viewed as largely similar because of their Western/individualistic orientations