The first direct evidence of pre-columbian sources of palygorskite for Maya Blue

Maya Blue, a nano-structured clay–organic complex of palygorskite and indigo, was used predominantly before the Spanish Conquest. It has fascinated chemists, material scientists, archaeologists and art historians for decades because it is resistant to the effect of acids, alkalis, and other reagents, and its rich color has persisted for centuries in the harsh tropical climate of southern Mesoamerica. One of its components, palygorskite, is part of modern Maya indigenous knowledge, and ethnohistoric and archaeological data suggest that its modern sources were probably utilized in Prehispanic times. Yet no direct evidence verifies that palygorskite was actually mined from these sources to make Maya Blue. Here we characterize these sources compositionally, and compare our analyses to those of Maya Blue from Chichén Itzá and Palenque. We demonstrate that the palygorskite in most of these samples came from modern mines, providing the first direct evidence for the use of these sources for making Maya Blue. These findings reveal that modern Maya indigenous knowledge about palygorskite, its mining, and its source locations, is at least seven centuries old.     

Emissions Trading,New Enclosures and Eco‐Social Contestation

Abstract: The central operating strategy within the 1997 Kyoto Protocol and most of the advanced capitalist world's environmental policy is to address climate change through the market mechanism known as emissions trading. Based upon government issuance and private trading of emissions reductions credits and offsets, this approach quickly rose to $135 billion in annual trading. But in the wake of the collapse of climate negotiations in Copenhagen and a world financial crisis which undermined market faith in derivative investments, carbon trading has an uncertain future. Linkages between deep‐rooted financial market and emissions market problems are revealing in spatio‐temporal terms, especially in the context of a deeper overaccumulation crisis and investors’ desperate need for new speculative outlets. It is in the nexus of the spatial and temporal aspects of carbon financing amidst resistance to “new enclosures” by adversely affected peoples, that broader‐based lessons for global/local environmental politics and climate policy can be learned.     

The ethico-politics of homo-ness: Beckett's How It Is and Casement's Black Diaries

In recent years, Beckett studies has taken an ‘ethical turn’ as critics have given increased attention to the status of the Other and otherness in the writer's oeuvre. How It Is, a key text for these critics, was written as Beckett was reading the newly published Black Diaries of Roger Casement, a volume that contains homoerotic content long considered scandalous for the Irish republican icon and yet offers a remarkable vision of social relations structured around sameness or what Leo Bersani calls ‘homo-ness’. Reading Beckett's novel alongside Casement's diaries reveals the significance of How It Is for thinking an ethico-politics that depends neither on the ideological foundations of the nation-state nor on critical perspectives that emphasise the primacy of difference, but rather on a fundamental reorientation of sociality. In this regard, Beckett's anti-redemptive narrative may be considered a work of penetrating utopian writing, which nonetheless reminds us of the hazards of utopian thought.     

Testing of Superelastic Recentering Pre-Strained Braces for Seismic Resistant Design

Over the past decade, the use of shape memory alloys (SMAs) in passive control devices has been explored. Nevertheless, some aspects in regards to the cyclic behavior of SMAs and the effect of pre-straining need to be clarified. In this study, small-scale shake table tests have been performed to explore the effectiveness of SMA bracing systems as compared to steel bracing systems. The reduced-scale experimental results imply that SMAs used in braces are more effective in controlling the response of a steel frame compared with a traditional bracing system. A finite element model (FEM) of the frame is developed in order to compare the analytical results with the shake table tests. Further, the effect of pre-straining the SMA braces is evaluated through both experimental and analytical studies. The results show that pre-straining improves the performance of the frame compared to the nonpre-strained case. However, as the level of pre-straining increases above approximately 1.0% to 1.5%, the benefits of pre-straining decrease compared with low-to-moderate pre-strain levels.