Comprehensive inter-laboratory calibration of reference materials for δ18O versus VSMOW using various on-line high-temperature conversion techniques

Internationally distributed organic and inorganic oxygen isotopic reference materials have been calibrated by six laboratories carrying out more than 5300 measurements using a variety of high-temperature conversion techniques (HTC) in an evaluation sponsored by the International Union of Pure and Applied Chemistry (IUPAC). To aid in the calibration of these reference materials, which span more than 125‰, an artificially enriched reference water (δ18O of +78.91‰) and two barium sulfates (one depleted and one enriched in 18O) were prepared and calibrated relative to VSMOW2 and SLAP reference waters. These materials were used to calibrate the other isotopic reference materials in this study. The seemingly large estimated combined uncertainties arise from differences in instrumentation and methodology and difficulty in accounting for all measurement bias. They are composed of the 3-fold standard errors directly calculated from the measurements and provision for systematic errors discussed in this paper. A primary conclusion of this study is that nitrate samples analyzed for δ18O should be analyzed with internationally distributed isotopic nitrates, and likewise for sulfates and organics. Authors reporting relative differences of oxygen-isotope ratios (δ18O) of nitrates, sulfates, or organic material should explicitly state in their reports the δ18O values of two or more internationally distributed nitrates (USGS34, IAEA-NO-3, and USGS35), sulfates (IAEA-SO-5, IAEA-SO-6, and NBS 127), or organic material (IAEA-601 benzoic acid, IAEA-602 benzoic acid, and IAEA-600 caffeine), as appropriate to the material being analyzed, had these reference materials been analyzed with unknowns. This procedure ensures that readers will be able to normalize the δ18O values at a later time should it become necessary. The high-temperature reduction technique for analyzing δ18O and δ2H is not as widely applicable as the well-established combustion technique for carbon and nitrogen stable isotope determination. To obtain the most reliable stable isotope data, materials should be treated in an identical fashion; within the same sequence of analyses, samples should be compared with working reference materials that are as similar in nature and in isotopic composition as feasible.

Class Movements in the New South Africa: Post-Colonial Politics, Neocolonialism, and Mimicry in Pieter-Dirk Uys’s MacBeki A Farce to be Reckoned With

This paper uses Homi Bhabha’s theory of colonial mimicry to analyze Pieter-Dirk Uys’s MacBeki: A Farce to be Reckoned With. In doing so I posit MacBeki is a colonial mimic, a character who comically imitates European gestures and language. MacBeki’s behaviour throughout the play highlights the dangers of greed and corruption in post-apartheid South Africa and encourages the play’s audience to respond with ridiculing laughter. My paper concludes by arguing that Uys’s play should be read as a hybrid text that draws on European dramatic styles and South African political events, staging a critical response to national uncertainties ahead of the 2009 South African elections

National Crises and Moments of Laughter in ‘Second Interregnum’ South African Drama, 2001-2014

This dissertation analyzes Anglophone South African dramatic critiques of national crises in the post-apartheid moment. Focusing specifically on the years after Nelson Mandela’s retirement, it examines some of the country’s prominent plays produced between 2001 and 2014. This was an important period of social and political change in South Africa, described by drama theorist Marcia Blumberg as a second interregnum where acts of reconciliation or disaffection were staged frequently (“Reconciling” 140). I build on Blumberg’s temporal model by extending her framework to account for recent events of national significance leading up to, and including, Mandela’s death in 2013. In addition to expanding her temporal framework, this project contributes new research on second interregnum drama by examining the rise of humour as a key component of the social and political criticism occurring in works from this period. My project is divided into four research chapters that highlight major challenges curtailing reconciliation and nation-building during this time: continuing class inequality, silence around mothers’ experiences of trauma during apartheid, ethnic minorities’ feelings of exclusion from national narratives, and continuing cycles of physical and psychological violence. Drama is an important barometer of the state of the nation. During apartheid, it was often used to oppose the state by staging “sites of conflict between different discourses” (Orkin 5). In the second interregnum drama continued to play a significant role in critiquing conditions by highlighting unaddressed areas of class, gender, and racial inequality. Playwrights in this period used drama to engage contemporary audiences in South Africa, and abroad, in order to encourage social change through debate and dialogue. This project analyzes the appearance of humour in second interregnum drama and the way it foregrounded unresolved tensions in the nation, especially discrepancies between personal and national narratives, and provided alternative ways of dealing with them. Moments of laughter emerge throughout the plays in this dissertation to challenge state discourses, critique social conditions, but also encourage expressions of unity through instances of collective laughter. Mapping key intersections between postcolonial studies and humour, this project provides new analysis of Pieter-Dirk Uys’s MacBeki: A Farce to be Reckoned With, Greig Coetzee’s Happy Natives, Fatima Dike’s The Return, Lara Foot Newton’s Reach, Ashwin Singh’s To House, Ntokozo Madlala and Mandisa Haarhoff’s Crush-hopper, Zakes Mda’s The Bells of Amersfoort, and David Peimer and Martina Griller’s Armed Response

The Labor Between Farm And Table: Cultivating An Urban Political Ecology Of Agrifood For The 21st Century

The variegated landscape of food production and consumption reveals a great deal about socionatural relations and processes of urbanization and globalization under capitalism. Food production has changed dramatically over time, shifting away (but never fully divorced) from the rural agrarian landscape to spaces that are characterized as industrial and/or urban. Workers transform nature at each stage in the food production process, not only on farms but also in processing plants, grocery stores, restaurants, and other spaces. This paper draws on urban political ecology (UPE) to position labor as central to understanding the socioecological relations embodied in food systems. It puts UPE in conversation with agrarian political economy, a decidedly un‐urban body of literature that nevertheless offers critical insight into the obstacles (and opportunities) that nature and labor pose to food systems development in an urbanizing world. Employing UPE\u27s dialectic conception of humans and nature, this paper highlights the role that non‐agricultural and urban‐based food labor plays in an increasingly complex global political economy of agrifood. Seeing both the “labor” and “nature” of food from the farm all the way to the table can reveal the myriad transformations, exchanges, and socioecological relations operating within the food system

Liquid-hydrogen rocket engine development at Aerojet, 1944 - 1950

This program demonstrated the feasibility of virtually all the components in present-day, high-energy, liquid-rocket engines. Transpiration and film-cooled thrust chambers were successfully operated. The first liquid-hydrogen tests of the coaxial injector was conducted and the first pump to successfully produce high pressures in pumping liquid hydrogen was tested. A 1,000-lb-thrust gaseous propellant and a 3,000-lb-thrust liquid-propellant thrust chamber were operated satisfactorily. Also, the first tests were conducted to evaluate the effects of jet overexpansion and separation on performance of rocket thrust chambers with hydrogen-oxygen propellants

Carotenoids are the likely precursor of a significant fraction of marine dissolved organic matter.

The ocean's biota sequester atmospheric carbon dioxide (CO2) in part by producing dissolved organic matter (DOM) that persists in the ocean for millennia. This long-term accumulation of carbon may be facilitated by abiotic and biotic production of chemical structures that resist degradation, consequently contributing disproportionately to refractory DOM. Compounds that are selectively preserved in seawater were identified in solid-phase extracted DOM (PPL-DOM) using comprehensive gas chromatography (GC) coupled to mass spectrometry (MS). These molecules contained cyclic head groups that were linked to isoprenoid tails, and their overall structures closely resembled carotenoid degradation products (CDP). The origin of these compounds in PPL-DOM was further confirmed with an in vitro β-carotene photooxidation experiment that generated water-soluble CDP with similar structural characteristics. The molecular-level identification linked at least 10% of PPL-DOM carbon, and thus 4% of total DOM carbon, to CDP. Nuclear magnetic resonance spectra of experimental CDP and environmental PPL-DOM overlapped considerably, which indicated that even a greater proportion of PPL-DOM was likely composed of CDP. The CDP-rich DOM fraction was depleted in radiocarbon (14C age > 1500 years), a finding that supports the possible long-term accumulation of CDP in seawater. By linking a specific class of widespread biochemicals to refractory DOM, this work provides a foundation for future studies that aim to examine how persistent DOM forms in the ocean

Reorganizing School Lunch for a More Just AndSustainable Food System In the US

Public school lunch programs in the United States are contested political terrains shaped by government agencies, civil society activists, and agri-food companies. The particular organization of these programs has consequences for public health, social justice, and ecological sustainability. This contribution draws on political economy, critical food studies, and feminist economics to analyze the US National School Lunch Program, one of the world\u27s oldest and largest government-sponsored school lunch programs. It makes visible the social and environmental costs of the heat-and-serve economy, where widely used metrics consider only the speed and volume of service as productive work. This study demonstrates that such a narrow understanding of the labor of lunch devalues care and undercuts the potential for school food provisioning to promote ecological and feminist goals. Further, it proposes a high road alternative and outlines an agenda for reorganizing school food provisioning to maximize care in all its dimension