A Study of the Sulfur Isotopic Composition of Martian Meteorites

ABSTRACT Title of Document: A STUDY OF THE SULFUR ISOTOPIC COMPOSITION OF MARTIAN METEORITES Heather B. Franz, Ph.D., 2012 Directed By: Professor James Farquhar, Department of Geology and ESSIC Sulfur is an important tracer for geochemical processes because it possesses four stable isotopes and forms natural compounds in a range of oxidation states. This element has been shown to undergo mass-independent isotopic fractionation (S-MIF) during laboratory photochemical experiments, which may provide clues to processes that have occurred both in the solar nebula and in planetary atmospheres. The surface of Mars has been found to contain ubiquitous sulfate minerals, marking this planet as an ideal candidate for sulfur isotope study. The shergottites comprise the youngest group of martian meteorites and the most representative of mantle-derived igneous rocks. Extraction and isotopic measurement of sulfur from 30 shergottites yield the first estimate of the juvenile martian sulfur composition, which matches within uncertainties that of Cañon Diablo Troilite. Analysis of martian meteorites spanning a range of ages from the shergottites, as young as ~150 Ma, to the nakhlites, ~1.3 Ga, reveals the presence of sulfur characterized by S-MIF compositions. These findings are interpreted as evidence for cycling of sulfur between an atmospheric reservoir where photochemical processing of sulfur-bearing gases occurred and a surface reservoir in which photochemical products were ultimately deposited. Anomalous sulfur has been detected in both sulfate and sulfide minerals, implying assimilation of sulfur from the martian surface into magmas. Differences in the S-MIF compositions of the nakhlites and shergottites may preserve a record of complementary sulfur formed by a single process or may indicate the operation of multiple photochemical processes at different times or geographical locations. Identification of the photochemical mechanism responsible for producing the anomalous sulfur observed in martian meteorites is important for constraining the atmospheric composition at the time the S-MIF signals were generated. Results of laboratory experiments with pure SO2 gas suggest that self-shielding is insufficient to explain the anomalous sulfur isotopic composition. This implies that an optically thick SO2 column in the martian atmosphere may not have been required for production of the observed signal

Non-formal educator use of evaluation results

Increasing demands for accountability in educational programming have resulted in increasing calls for program evaluation in educational organizations. Many organizations include conducting program evaluations as part of the job responsibilities of program staff. Cooperative Extension is a complex organization offering non-formal educational programs through land grant universities. Many Extension services require non-formal educational program evaluations be conducted by field-based Extension educators. Evaluation research has focused primarily on the efforts of professional, external evaluators. The work of program staff with many responsibilities including program evaluation has received little attention. This study examined how field based Extension educators (i.e. program staff) in four Extension services use the results of evaluations of programs that they have conducted themselves. Four types of evaluation use are measured and explored; instrumental use, conceptual use, persuasive use and process use. Results indicate that there are few programmatic changes as a result of evaluation findings among the non-formal educators surveyed in this study. Extension educators tend to use evaluation results to persuade others about the value of their programs and learn from the evaluation process. Evaluation use is driven by accountability measures with very little program improvement use as measured in this study. Practical implications include delineating accountability and program improvement tasks within complex organizations in order to align evaluation efforts and to improve the results of both. There is some evidence that evaluation capacity building efforts may be increasing instrumental use by educators evaluating their own programs

A Forecast of Reduced Solar Activity and Its Implications for NASA

The "Solar Dynamo" method of solar activity forecasting is reviewed. Known generically as a 'precursor" method, insofar as it uses observations which precede solar activity generation, this method now uses the Solar Dynamo Amplitude (SODA) Index to estimate future long-term solar activity. The peak amplitude of the next solar cycle (#24), is estimated at roughly 124 in terms of smoothed F10.7 Radio Flux and 74 in terms of the older, more traditional smoothed international or Zurich Sunspot number (Ri or Rz). These values are significantly smaller than the amplitudes of recent solar cycles. Levels of activity stay large for about four years near the peak in smoothed activity, which is estimated to occur near the 2012 timeflame. Confidence is added to the prediction of low activity by numerous examinations of the Sun s weakened polar field. Direct measurements are obtained by the Mount Wilson Solar Observatory and the Wilcox Solar Observatory. Further support is obtained by examining the Sun s polar faculae (bright features), the shape of coronal soft X-ray "holes," and the shape of the "source surface" - a calculated coronal feature which maps the large scale structure of the Sun s field. These features do not show the characteristics of well-formed polar coronal holes associated with typical solar minima. They show stunted polar field levels, which are thought to result in stunted levels of solar activity during solar cycle #24. The reduced levels of solar activity would have concomitant effects upon the space environment in which satellites orbit. In particular, the largest influences would affect orbit determination of satellites in LEO (Low Earth Orbit), based upon the altered thermospheric and exospheric densities. A decrease in solar activity would result in smaller satellite decay rates, as well as fewer large solar events that can destroy satellite electronic functions. Other effects of reduced solar activity upon the space environment include enhanced galactic cosmic rays and more space debris at low altitudes (from the decay of old satellite parts, etc.). The reasons are well known: namely, solar activity serves to sweep the inner heliosphere of galactic cosmic rays, and lower exospheric densities result in decreased drag on LEO debris, allowing longer lifetimes

The Neuromuscular Origins of Kinematic Variability during Perturbed Walking

We investigated the neuromuscular contributions to kinematic variability and thus step to step adjustments in posture and foot placement across a range of walking speeds in response to optical flow perturbations of different amplitudes using a custom virtual environment. We found that perturbations significantly increased step width, decreased step length, and elicited larger trunk sway compared to normal walking. However, perturbation-induced effects on the corresponding variabilities of these measurements were much more profound. Consistent with our hypotheses, we found that: (1) perturbations increased EMG activity of the gluteus medius and postural control muscles during leg swing, and increased antagonist leg muscle coactivation during limb loading in early stance, and (2) changes in the magnitude of step to step adjustments in postural sway and lateral foot placement positively correlated with those of postural control and gluteus medius muscle activities, respectively, in response to perturbations. However, (3) interactions between walking speed and susceptibility to perturbations, when present, were more complex than anticipated. Our study provides important mechanistic neuromuscular insight into walking balance control and important reference values for the emergence of balance impairment

A Brief Report on a Facilitated Approach to Connect Cooperative Extension Southern Region State-Level Health Specialists

Improving the nation’s health will require collaboration among many stakeholders and systems, including representatives from Cooperative Extension Services (CES). This paper describes the process of establishing a multistate collaboration and discusses initial outcomes of a third-party facilitated participatory planning meeting. State-level specialists with expertise and responsibilities in “health” promotion participated. Satisfaction with meeting format; feasibility, acceptability, and appropriateness of the proposed approach to public health impact; and general meeting feedback were collected through a survey and cultural artifacts (e.g., notes, worksheets). Preparation and attendance costs were captured. Seventeen of the 20 attendees (85%) responded to the survey and reported the process was satisfactory and the proposed plan for moving forward was feasible, acceptable, and appropriate. The meeting cost was $1,011 per attendee. The process mobilized a multistate Extension collaborative to promote health but revealed potential cost-benefit challenges. Leveraging resources is necessary to plan, implement, and measure collaborative public health efforts. Future data on outcomes will show if the process leads to intended objectives. If successful, this approach can be replicated across CES for stronger impacts

Evaluating for Impact: Professional Development Educational Content Delivery Through Learning Communities

The National 4-H Council Learning Priorities team developed educational content for professional development to increase evaluation capacity and evaluation skills for 4-H educators. Extension specialists in Oregon, Vermont, and Virginia piloted Evaluating for Impact curriculum through learning communities. Lessons learned from the pilot project include the overall success of content in increasing individual participant evaluation skills, reflection on the comprehensive and academically rigorous nature of the curriculum, a need for an experienced evaluator to lead the circles, and an ability to customize the curriculum to the evaluation levels of participants

Evolved Gas Measurements Planned for the Lower Layers of the Gale Crater Mound with the Sample Analysis at Mars Instrument Suite

The lower mound strata of Gale Crater provide a diverse set of chemical environments for exploration by the varied tools of the Curiosity Rover of the Mars Science Laboratory (MSL) Mission. Orbital imaging and spectroscopy clearly reveal distinct layers of hydrated minerals, sulfates, and clays with abundant evidence of a variety of fluvial processes. The three instruments of the MSL Sample Analysis at aMars (SAM) investigation, the Quadrupole Mass Spectrometer (QMS), the Tunable Laser Spectrometer (TLS), and the Gas Chromatograph (GC) are designed to analyze either atmospheric gases or volatiles thermally evolved or chemically extracted from powdered rock or soil. The presence or absence of organic compounds in these layers is of great interest since such an in situ search for this type of record has not been successfully implemented since the mid-60s Viking GCMS experiments. However, regardless of the outcome of the analysis for organics, the abundance and isotopic composition of thermally evolved inorganic compounds should also provide a rich data set to complement the mineralogical and elemental information provided by other MSL instruments. In addition, these evolved gas analysis (EGA) experiments will help test sedimentary models proposed by Malin and Edgett (2000) and then further developed by Milliken et al (2010) for Gale Crater. In the SAM EGA experiments the evolution temperatures of H2O, CO2, SO2, O2, or other simple compounds as the samples are heated in a helium stream to 1000 C provides information on mineral types and their associations. The isotopic composition of O, H, C, and S can be precisely determined in several evolved compounds and compared with the present day atmosphere. Such SAM results might be able to test mineralogical evidence of changing sedimentary and alteration processes over an extended period of time. For example, Bibring et al (2006) have suggested such a major shift from early nonacidic to later acidic alteration. We will illustrate through a variety of evolved gas experiments implemented under SAM-like gas flow and temperature ramp conditions on terrestrial analog minerals on high fidelity Sam breadboards the type of chemical information we expect SAM to provide

Enhancing Accountability: ServSafe™ Impact Template Delivers

Generating statewide impact data from Extension programs can be challenging. To streamline reporting, Extension specialists, with the help of county agents and administrators, generated a statewide impact statement for the ServSafe™ program in Virginia. This template includes knowledge gain, behavior change, and economic impact from participants generated from current standardized evaluation methods used by all Extension educators across the state. Providing this template for agents resulted in easier, more consistent yearly reporting for those agents administering the program

Heinz J. Drügh, Anders-Rede. Zur Struktur und historischen Systematik des Allegorischen. 2000

BACKGROUND: Our current knowledge of modifiable risk factors to prevent myocardial infarction (MI) in young and middle-aged women is limited, and the impact of diet is largely unknown. Dietary flavonoids exert potential beneficial effects on endothelial function in short-term trials; however the relationship between habitual intake and risk of MI in women in unknown. METHODS AND RESULTS: We followed 93,600 women aged 25–42 years from the Nurses’ Health Study (NHS) II who were healthy at baseline (1989) to examine the relationship between anthocyanins and other flavonoids and risk of MI. Intake of flavonoid sub-classes were calculated from validated food-frequency questionnaires collected every 4 years using an updated and extended USDA database. During 18 years of follow-up, 405 cases of MI were reported. An inverse association between higher intake of anthocyanins and risk of MI was observed (Hazard Ratio [HR]: 0.68; 95% confidence interval [CI] 0.49–0.96; p=0.03 comparing highest versus lowest quintiles) after multivariate adjustment. The addition of intermediate conditions, including history of hypertension, did not significantly attenuate the relationship (HR 0.70; 0.50–0.97; p=0.03). Combined intake of two anthocyanin-rich foods, blueberries and strawberries, tended to be associated with a decreased risk of MI (HR 0.66; 0.40–1.08) comparing those consuming >3 servings/week to those with lower intake. Intakes of other flavonoid sub-classes were not significantly associated with MI risk. CONCLUSIONS: A high intake of anthocyanins may reduce MI risk in predominately young women. Intervention trials are needed to further examine the health impact of increasing intakes of commonly consumed anthocyanin-rich foods