Coherent diffractive imaging of microtubules using an X-ray laser

X-ray free electron lasers (XFELs) create new possibilities for structural studies of biological objects that extend beyond what is possible with synchrotron radiation. Serial femtosecond crystallography has allowed high-resolution structures to be determined from micro-meter sized crystals, whereas single particle coherent X-ray imaging requires development to extend the resolution beyond a few tens of nanometers. Here we describe an intermediate approach: the XFEL imaging of biological assemblies with helical symmetry. We collected X-ray scattering images from samples of microtubules injected across an XFEL beam using a liquid microjet, sorted these images into class averages, merged these data into a diffraction pattern extending to 2 nm resolution, and reconstructed these data into a projection image of the microtubule. Details such as the 4 nm tubulin monomer became visible in this reconstruction. These results illustrate the potential of single-molecule X-ray imaging of biological assembles with helical symmetry at room temperature

Electronic damage in S atoms in a native protein crystal induced by an intense X-ray free-electron laser pulse

Current hard X-ray free-electron laser (XFEL) sources can deliver doses to biological macromolecules well exceeding 1 GGy, in timescales of a few tens of femtoseconds. During the pulse, photoionization can reach the point of saturation in which certain atomic species in the sample lose most of their electrons. This electronic radiation damage causes the atomic scattering factors to change, affecting, in particular, the heavy atoms, due to their higher photoabsorption cross sections. Here, it is shown that experimental serial femtosecond crystallography data collected with an extremely bright XFEL source exhibit a reduction of the effective scattering power of the sulfur atoms in a native protein. Quantitative methods are developed to retrieve information on the effective ionization of the damaged atomic species from experimental data, and the implications of utilizing new phasing methods which can take advantage of this localized radiation damage are discussed

"A convenient truth": air travel passengers' willingness to pay to offset their CO2 emissions

Several economic reviews demonstrate the substantial costs related to climate change and consequently call for early action. These reviews, however, have been limited to measuring ‘objective’ risks and expected material damage related to climate change. The ‘subjective’ perceived risk of climate change and society’s willingness to pay (WTP) to avoid these risks are expected to provide an important additional motivation for direct action. We investigate whether and why air travel passengers—an increasingly important source of greenhouse gas emissions—are supportive of measures that increase the cost of their travel based on the polluter pays principle and compensate the damage caused by their flight. Compared to the results of the few previous studies that have elicited WTP estimates for climate policy more generally, our results appear to be at the lower end of the scale, while a comparison to estimates of the social cost of carbon shows that the average WTP estimate in this study is close to the estimated marginal damage cost. Although significant differences are found between travellers from Europe, North America, Asia and the rest of the world, we show that there exists a substantial demand for climate change mitigation action. The positive risk premium over and above the expected property damage cost assessments should be accounted for more explicitly in economic reviews as it will add to the burden of proof of direct action. Measurements of passenger WTP will help policy makers to design effective financial instruments aimed at discouraging climate-unfriendly travel activities as well as to generate funds for the measures directed at climate change mitigation and adaptation. Based on stated WTP by travellers to offset their greenhouse gas emissions, funds in the order of magnitude of €23 billion could be generated annually to finance climate change mitigation activities

Precise U-Pb mineral ages, Rb-Sr and Sm-Nd systematics for the Great Dyke, Zimbabwe - constraints on late Archean events in the Zimbabwe craton and Limpopo belt

U–Pb dating of zircon and rutile from bronzitites of the P1 pyroxenite layer of the Great Dyke precisely constrains the crystallization age of this part of the intrusion to 2575.4±0.7 Ma. Whole rock Rb–Sr and Sm–Nd data of various rock types sampled along the entire length of the Great Dyke record inhomogeneous initial isotope ratios, and also later (<1.5 Ga) disturbances of the Rb–Sr and Sm–Nd isotope systems. The 2575.4±0.7 Ma emplacement age of the Great Dyke is ≈120 Ma older than assumed until recently, and calls for new interpretations of the crustal development of the Zimbabwe craton. Close temporal links between the intrusion of the Great Dyke and the emplacement of late Archean granitoids (Chilimanzi and Razi suites) of the Zimbabwe craton are indicated by the new precise age data. The Chilimanzi and Razi suites of granitoids form at least two sub-suites, which can be described as pre- and post-Great Dyke in age. The Great Dyke age now falls within the range of ages for tectonic events in the Limpopo belt including granitoid magmatism, metamorphism, and thrusting of the Northern Marginal Zone over the Zimbabwe craton. A west-to-east diachroneity in both thrusting and crustal stabilization is suggested by the observations that the Great Dyke cuts across the thrust in the west, but syn-tectonic granitoids that are younger than the Great Dyke are deformed by the thrusting in the east. Intrusion of the Great Dyke cannot be linked to collision of the Zimbabwe and Kaapvaal cratons. The overlap in ages of intrusion of the Great Dyke and late Archean events in the Zimbabwe craton shows that Archean crust was cratonized shortly after large-scale melting and granite intrusion

Metallogenesis of the Redwing gold mine, Mutare greenstone belt, Zimbabwe

Orientadora: Profa. Dra. Katya Regina Isaguirre-TorresDissertação (mestrado) - Universidade Federal do Paraná, Pró-Reitoria de Pesquisa e Pós-Graduação, Programa de Pós-Graduação em Meio Ambiente e Desenvolvimento. Defesa : Curitiba, 26/03/2020Inclui referências: p. 104-115Resumo: A natureza é comumente vista pelo poder hegemônico como recurso, meio, conjunto de elementos naturais, a ser protegida de acordo com os interesses humanos. O ser humano, por sua vez, encontra-se distante dessa natureza, seu relacionamento com ela pauta-se no domínio, no extrativismo, na transformação da natureza em bem. Seguindo o caminho da modernidade ocidental, para o direito o ser humano é sujeito, e vai além, é sujeito de direito. A natureza ocupava as margens do direito até 2008, quando o Equador inovou ao trazer em seu texto constitucional os direitos da natureza e a ampliação da categoria sujeito de direito à natureza. Tal inovação se afasta da episteme moderna ocidental e se aproxima das ontologias e cosmologias dos povos tradicionais latino-americanos, segundo as quais a natureza e o ser humano existem em condição de complementariedade, relacionalidade e harmonia. Neste trabalho o movimento pelos direitos da natureza é entendido como movimento decolonial pela sua aproximação com os saberes localizados e por constituir-se como proposta pós-extrativista. Feito com base em revisão bibliográfica e estudo jurisprudência, esta dissertação é construída com base nos conceitos de natureza, sujeito de direito e decolonialidade. O estudo recupera os momentos que levam a humanidade a separar-se da natureza, bem como o momento de aproximação e retorno com o giro decolonial, demonstrando como está sendo aplicada a abstração jurídica do sujeito de direito nesse contexto. Com a análise do movimento jurídico e filosófico que torna a natureza um sujeito de direito, verifica-se que essa perspectiva sociojurídica auxilia na denúncia da colonialidade que afeta a natureza e subjuga os povos na América Latina. A natureza que antes não possuía espaço no campo jurídico, passa a ser sujeito de direito. As decisões proferidas a respeito ainda mantêm um caráter protetivo, no sentido de proteger a natureza para o usufruto da humanidade e futuras gerações, ao invés de emancipador. Apesar disso, a ressignificação do sujeito de direito dá fundamento às lutas sociais e impulsiona os povos a romper com as amarras da modernidade/colonialidade. Palavras-chave: Natureza. Direito. Sujeito de direito. Giro decolonial. Direitos da natureza.Abstract: Nature is commonly seen by hegemonic power as a resource, environmental, set of natural elements, to be protected according to human interests. The human being, in turn, is distant from this nature, his relationship with it is based on dominance, extraction, the transformation of nature into goods. Following the path of western modernity, the human being is subject to law, and goes further, subject of law. In law, nature occupied the margins until 2008, when Ecuador innovated by bringing in its constitutional text the rights of nature and the expansion of the category subject of law to the nature. Such innovation moves away from the modern western episteme and comes close to the ontologies and cosmologies of the traditional Latin American peoples, according to which nature and the human being exist in conditions of complementarity, relationality and harmony. In this work, the movement for the rights of nature is understood as a decolonial movement for its approximation with the localized knowledge and for constituting itself as a postextractive proposal. Based on a bibliographic review and case law study, this dissertation is based on the concepts of nature, subject of law and decoloniality. The study recovers the moments that lead humanity to separate itself from nature, as well as the moment of approach and return with the decolonial turn, demonstrating how the legal abstraction of the subject of law is being applied in this context. With the analysis of the legal and philosophical movement that makes nature a subject of law, it appears that this socio-legal perspective helps in denouncing the coloniality that affects nature and subjugates people in Latin America. Nature that previously had no space in the legal field is now subject to law. Decisions made in this regard still retain a protective line, in the sense of protecting for the enjoyment of humanity and future generations, instead of an emancipatory character. In spite of this, the resignification of the subject of law gives basis to social struggles and impels people to break with the bonds of modernity / coloniality. Keywords: Nature. Rights. Subject of law. Decolonial Turn. Rights of nature