Geochemical and Particle Size Analysis of East Antarctic Shelf Sediments Through the Eocene Oligocene Transition

The Eocene Oligocene Transition (EOT) at ~34 million years ago (Ma), marked the global change from greenhouse to icehouse, and the establishment of the East Antarctic Ice Sheet (EAIS). The timing involved with initiation of the EAIS and ice growth during the EOT is still poorly understood due to poor core recovery. The purpose of this study was to expand upon existing knowledge of EAIS dynamics by applying updated age models to geochemical and sedimentological records from three marginal shelf sites that contain Eocene and or Oligocene sediments. This study used inductively coupled plasma optical emission spectrometry and mass spectrometry (ICP-OES/ICP-MS) to determine the bulk chemical composition of samples from marginal east Antarctic shelf sites: ODP Site 1166A [O’Brien et al., 2001] and IODP Site U1360 [Expedition 318 Scientists, 2010]. Particle size analysis was conducted on sediments from west Antarctic ODP Site 696 [Barker et al., 1988], and the distributions were compared to particle size data from Ciarletta [2014] for Sites 1166 and U1360. Overall, Site 696 shows a fining upward sequence indicative of a marine transgression, that could have been caused by depression of continental crust as the EAIS grew or tectonic deepening during the formation of the Powell basin. Major element data was used to calculate various paleoclimate proxies including the Chemical Index of Alteration (CIA), mean annual temperatures, and mean annual precipitation. The paleoclimate of a region can affect the advance and retreat of ice and is therefore important in the study of glaciation in Antarctica. Results show a dominant warm humid environment for the Late Eocene (Site 1166); in contrast, the Lower Oligocene (Site U1360) shows a cooler more arid environment. The provenance of sediments was constrained by calculating Al2O3/TiO2 ratios. Al and Ti are conservative elements and are representative of their source material; therefore, the ratios can be a good indicator of changes in provenance. It was determined that a slight provenance change occurred at Site 1166 and may indicate a glacial advance and retreat. At Site U1360 the source remained relatively the same. Changes in the Al/Ti ratios at Site U1360 are likely due to changes in particle size

States of Childhood

A number of curious communities sprang up across the United States in the late nineteenth and early twentieth century: simulated cities, states, and nations in which children played the roles of legislators, police officers, bankers, journalists, shopkeepers, and other adults. They performed real work—passing laws, growing food, and constructing buildings, among other tasks—inside virtual worlds. In this book, Jennifer Light examines the phenomena of “junior republics” and argues that they marked the transition to a new kind of “sheltered” childhood for American youth. Banished from the labor force and public life, children inhabited worlds that mirrored the one they had left. Light describes the invention of junior republics as independent institutions and how they were later established at schools, on playgrounds, in housing projects, and on city streets, as public officials discovered children's role playing helped their bottom line. The junior republic movement aligned with cutting-edge developmental psychology and educational philosophy, and complemented the era's fascination with models and miniatures, shaping educational and recreational programs across the nation. Light's account of how earlier generations distinguished "real life" from role playing reveals a hidden history of child labor in America and offers insights into the deep roots of such contemporary concepts as gamification, play labor, and virtuality

Leading by Example

Leading by example, three nonprofits faced tough decisions and significant organizational changes to ensure the sustainability and growth of successful leadership programs in Maine. Lessons shared provide insights that may be useful to other nonprofits facing similar challenges

Child Care in the Postwelfare Reform Era: Analysis and Strategies for Advocates

Adequate child care is essential to enable poor women to support their families with work outside the home. In 1994 the U.S. General Accounting Office found that offering a child care subsidy to poor mothers increased the likelihood by 15 percent that the mothers would work. An Illinois study found that 20 percent of parents who left public assistance for work returned to assistance because of child care problems. In Minnesota a study found that lack of child care caused 14 percent of parents awaiting child care subsidies to leave their jobs and rely on public assistance. These studies confirm what advocates know: Poor parents, like other parents, cannot work without child care. The goal of this article is to assist advocates in helping their clients access quality child care and assuring that they do not lose needed public assistance when child care is unavailable

Hexafluorosilicate and tetrafluoroborate coordination to lead(II) di- and tri-imine complexes – Unusual fluoroanion coordination modes

AbstractLead(II) tetrafluoroborate and hexafluorosilicate complexes with 2,2′-bipyridyl, 1,10-phenathroline and 2,2′:6′,2″-terpyridyl have been prepared from the ligand and lead salt in aqueous/MeCN. Crystal structures are reported for [Pb(bipy)2(SiF6)], [Pb(phen)2(SiF6)] and [Pb(bipy)2(BF4)2] which are dinuclear with each lead coordinated “cis” to the two diimines and with the bridging fluoroanions completing eight or nine-coordination. [Pb(phen)2(BF4)2] is eight-coordinate and mononuclear with “cis” diimines and two κ2-BF4− groups. [Pb(phen)2(H2O)2(SiF6)] is also mononuclear with a κ2-SiF62− group and two coordinated water molecules. Reaction of Pb(BF4)2 with 2,2′:6′,2″-terpyridyl gave only [Pb(terpy)3][BF4]2, but Pb(SiF6) produced [Pb(terpy)(H2O)(SiF6)], which is a chain polymer with bridging SiF62− groups and significant π-stacking of the imine rings. The work has identified a number of coordination modes of the SiF62− anion, which has been little used in coordination chemistry but proves to be versatile and also stable (to decomposition/hydrolysis)

Water column barium sulfate dissolution and shielding by organic matter aggregates: Implications for the pelagic barite proxy

T.L. was partially supported by a U.S. Department of Defense National Defense Science and Engineering Graduate Student Fellowship and a Ruth Newmark Scholarship from the UCSD Friends of the International Center. M. G. was supported by the Triton Research and Experiential Learning Scholars program. The authors thank Benjamin Gruber, Cecilia de la Prada, and Dr. Erica Ferrer and for their valuable assistance.Pelagic barite (BaSO4) and related proxies are useful tools for reconstructing the marine carbon cycle. The factors controlling pelagic barite dissolution in the ocean water column are poorly understood, which adds uncertainty to Ba-based reconstructions. Here, we conducted static laboratory incubations to test the sensitivity of barium sulfate dissolution rate to a range of commonly occurring seawater pH, salinity, and temperature conditions. We observed relatively rapid dissolution rates ranging from 1.7 & PLUSMN; 0.4 to 3.4 & PLUSMN; 0.8 pg BaSO4 day-1 for these experiments, and we did not observe statistically significant differences in the rate of dissolution with varying pH, salinity, or temperature. The slowest dissolution rate observed in these experiments suggests that an average barium sulfate crystal would survive in the ocean water column just 6.2 & PLUSMN; 0.3 days. We estimate that an average isolated pelagic barite crystal would take 67 years to sink down through the water column, so our experiments imply that solitary pelagic barite crystals do not survive this transit. We conducted an additional experiment on a roller table to assess the impact of organic matter aggregates on barium sulfate dissolution. Free barium sulfate crystals incubated on the roller table dissolved even more rapidly than crystals in the static experiment (19 & PLUSMN; 7 pg BaSO4 day � 1), but barium sulfate crystals incubated with organic matter aggregates showed little sign of dissolution over time. Our findings suggest that organic matter aggregates play a vital role in shielding pelagic barite from dissolution in the water column. This implies that pelagic barite in ocean sediments records the arrival of organic detritus to the seafloor, not just barite crystal formation in sinking organic matter in the upper water column. Additional work is needed to determine which aspects of the marine carbon cycle the pelagic barite proxy captures.U.S. Department of Defense National Defense Science and Engineering Graduate Student FellowshipUCSD Friends of the International CenterTriton Research and Experiential Learning Scholars progra

Higher Education Exchange:2003

This annual publication serves as a forum for new ideas and dialogue between scholars and the larger public. Essays explore ways that students, administrators, and faculty can initiate and sustain an ongoing conversation about the public life they share.The Higher Education Exchange is founded on a thought articulated by Thomas Jefferson in 1820: "I know no safe depository of the ultimate powers of the society but the people themselves; and if we think them not enlightened enough to exercise their control with a wholesome discretion, the remedy is not to take it from them, but to inform their discretion by education."In the tradition of Jefferson, the Higher Education Exchange agrees that a central goal of higher education is to help make democracy possible by preparing citizens for public life. The Higher Education Exchange is part of a movement to strengthen higher education's democratic mission and foster a more democratic culture throughout American society.Working in this tradition, the Higher Education Exchange publishes interviews, case studies, analyses, news, and ideas about efforts within higher education to develop more democratic societies

Taking action in a changing world

In the last hours of CHI 2017, a group of researchers from universities and businesses across the northern hemisphere sat down together to consider “Taking Action in a Changing World”. The title of the special interest group (SIG) is significant; it speaks of having an impact, of the politics on which we wish to have an impact, and also the dynamism of the structures and systems around us. There is no special mention of technology. In other words, it is a departure from business-as-usual HCI