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48,794 result(s) for "Huber, T."
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Lifeblood
If our oil addiction is so bad for us, why don't we kick the habit? Looking beyond the usual culprits-Big Oil, petro-states, and the strategists of empire-Lifeblood finds a deeper and more complex explanation in everyday practices of oil consumption in American culture. Those practices, Matthew T. Huber suggests, have in fact been instrumental in shaping the broader cultural politics of American capitalism. How did gasoline and countless other petroleum products become so central to our notions of the American way of life? Huber traces the answer from the 1930s through the oil shocks of the 1970s to our present predicament, revealing that oil's role in defining popular culture extends far beyond material connections between oil, suburbia, and automobility. He shows how oil powered a cultural politics of entrepreneurial life-the very American idea that life itself is a product of individual entrepreneurial capacities. In so doing he uses oil to retell American political history from the triumph of New Deal liberalism to the rise of the New Right, from oil's celebration as the lifeblood of postwar capitalism to increasing anxieties over oil addiction. Lifeblood rethinks debates surrounding energy and capitalism, neoliberalism and nature, and the importance of suburbanization in the rightward shift in American politics. Today, Huber tells us, as crises attributable to oil intensify, a populist clamoring for cheap energy has less to do with American excess than with the eroding conditions of life under neoliberalism.
Calculation of the quark and gluon form factors to three loops in QCD
We describe the calculation of the three-loop QCD corrections to quark and gluon form factors. The relevant three-loop Feynman diagrams are evaluated and the resulting three-loop Feynman integrals are reduced to a small set of known master integrals by using integration-by-parts relations. Our calculation confirms the recent results by Baikov et al. for the three-loop form factors. In addition, we derive the subleading terms for the fermion-loop type contributions to the three-loop form factors which are required for the extraction of the fermionic contributions to the four-loop quark and gluon collinear anomalous dimensions. The finite parts of the form factors are used to determine the hard matching coefficients for the Drell-Yan process and inclusive Higgs-production in soft-collinear effective theory.
Rapid ocean acidification and protracted Earth system recovery followed the end-Cretaceous Chicxulub impact
Mass extinction at the Cretaceous–Paleogene (K-Pg) boundary coincides with the Chicxulub bolide impact and also falls within the broader time frame of Deccan trap emplacement. Critically, though, empirical evidence as to how either of these factors could have driven observed extinction patterns and carbon cycle perturbations is still lacking. Here, using boron isotopes in foraminifera, we document a geologically rapid surface-ocean pH drop following the Chicxulub impact, supporting impact-induced ocean acidification as amechanism for ecological collapse in the marine realm. Subsequently, surface water pH rebounded sharply with the extinction of marine calcifiers and the associated imbalance in the global carbon cycle. Our reconstructed water-column pH gradients, combined with Earth system modeling, indicate that a partial ∼50% reduction in global marine primary productivity is sufficient to explain observed marine carbon isotope patterns at the K-Pg, due to the underlying action of the solubility pump. While primary productivity recovered within a few tens of thousands of years, inefficiency in carbon export to the deep sea lasted much longer. This phased recovery scenario reconciles competing hypotheses previously put forward to explain the K-Pg carbon isotope records, and explains both spatially variable patterns of change in marine productivity across the event and a lack of extinction at the deep sea floor. In sum, we provide insights into the drivers of the last mass extinction, the recovery of marine carbon cycling in a postextinction world, and the way in which marine life imprints its isotopic signal onto the geological record.
A time-dependent order parameter for ultrafast photoinduced phase transitions
The temporal dynamics of phase transitions in strongly correlated states of matter are often dictated by the interplay between structural and electronic degrees of freedom. These are now probed in a perovskite manganite using an X-ray free-electron laser, and found to be well described by a single order parameter. Strongly correlated electron systems often exhibit very strong interactions between structural and electronic degrees of freedom that lead to complex and interesting phase diagrams 1 , 2 . For technological applications of these materials it is important to learn how to drive transitions from one phase to another. A key question here is the ultimate speed of such phase transitions, and to understand how a phase transition evolves in the time domain 3 , 4 , 5 , 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 . Here we apply time-resolved X-ray diffraction to directly measure the changes in long-range order during ultrafast melting of the charge and orbitally ordered phase in a perovskite manganite. We find that although the actual change in crystal symmetry associated with this transition occurs over different timescales characteristic of the many electronic and vibrational coordinates of the system, the dynamics of the phase transformation can be well described using a single time-dependent ‘order parameter’ that depends exclusively on the electronic excitation.
Tree-Based Unrooted Phylogenetic Networks
Phylogenetic networks are a generalization of phylogenetic trees that are used to represent non-tree-like evolutionary histories that arise in organisms such as plants and bacteria, or uncertainty in evolutionary histories. An unrooted phylogenetic network on a non-empty, finite set X of taxa, or network, is a connected, simple graph in which every vertex has degree 1 or 3 and whose leaf set is X. It is called a phylogenetic tree if the underlying graph is a tree. In this paper we consider properties of tree-based networks, that is, networks that can be constructed by adding edges into a phylogenetic tree. We show that although they have some properties in common with their rooted analogues which have recently drawn much attention in the literature, they have some striking differences in terms of both their structural and computational properties. We expect that our results could eventually have applications to, for example, detecting horizontal gene transfer or hybridization which are important factors in the evolution of many organisms.
Structural basis of p62/SQSTM1 helical filaments and their role in cellular cargo uptake
p62/SQSTM1 is an autophagy receptor and signaling adaptor with an N-terminal PB1 domain that forms the scaffold of phase-separated p62 bodies in the cell. The molecular determinants that govern PB1 domain filament formation in vitro remain to be determined and the role of p62 filaments inside the cell is currently unclear. We here determine four high-resolution cryo-EM structures of different human and Arabidopsis PB1 domain assemblies and observed a filamentous ultrastructure of p62/SQSTM1 bodies using correlative cellular EM. We show that oligomerization or polymerization, driven by a double arginine finger in the PB1 domain, is a general requirement for lysosomal targeting of p62. Furthermore, the filamentous assembly state of p62 is required for autophagosomal processing of the p62-specific cargo KEAP1. Our results show that using such mechanisms, p62 filaments can be critical for cargo uptake in autophagy and are an integral part of phase-separated p62 bodies. PB1-mediated oligomerization of p62/SQSTM1 is essential for its function as a selective autophagy receptor. Here the authors present the cryo-EM structures of human and Arabidopsis PB1 domain helical assemblies and find that a conserved double arginine finger in the PB1 domain is important for p62 polymerisation and lysosomal targeting of p62.
Optical trapping of an ion
Isolating ions and atoms from the environment is essential in experiments on a quantum level 1 , 2 , 3 , 4 . For decades, this has been achieved by trapping ions with radiofrequency 5 fields and neutral particles with optical fields 6 . Here we demonstrate the trapping of an ion by interaction with light. The lifetime in the optical trap is several milliseconds, allowing hundreds of oscillations in the optical potential, and could be enhanced by established methods 6 . These results could form the starting point for combining the advantages of optical trapping and ions. Extending the approach to optical lattices could support developments in experimental quantum simulations 7 . As well as simulating complex spin systems with trapped ions, a new class of quantum simulations could be enabled that combines atoms and ions in a common lattice (Cirac, J.I., personal communication; Zoller, P., personal communication). Furthermore, ions could be embedded into quantum degenerate gases, thereby avoiding the inevitable excess kinetic energy of ions in radiofrequency traps, which currently limits cold-chemistry experiments 8 , 9 . It is well-known that neutral atoms can be trapped using visible light, but the trapping of ions is typically achieved using radiofrequency electromagnetic fields. Researchers have now developed an optical ion trapping technique that may be useful for applications ranging from quantum physics to ultracold chemistry.
MEDLINE search retrieval issues: A longitudinal query analysis of five vendor platforms
This study compared the results of data collected from a longitudinal query analysis of the MEDLINE database hosted on multiple platforms that include PubMed, EBSCOHost, Ovid, ProQuest, and Web of Science. The goal was to identify variations among the search results on the platforms after controlling for search query syntax. We devised twenty-nine cases of search queries comprised of five semantically equivalent queries per case to search against the five MEDLINE database platforms. We ran our queries monthly for a year and collected search result count data to observe changes. We found that search results varied considerably depending on MEDLINE platform. Reasons for variations were due to trends in scholarly publication such as publishing individual papers online first versus complete issues. Some other reasons were metadata differences in bibliographic records; differences in the levels of specificity of search fields provided by the platforms and large fluctuations in monthly search results based on the same query. Database integrity and currency issues were observed as each platform updated its MEDLINE data throughout the year. Specific biomedical bibliographic databases are used to inform clinical decision-making, create systematic reviews, and construct knowledge bases for clinical decision support systems. They serve as essential information retrieval and discovery tools to help identify and collect research data and are used in a broad range of fields and as the basis of multiple research designs. This study should help clinicians, researchers, librarians, informationists, and others understand how these platforms differ and inform future work in their standardization.
Abrupt episode of mid-Cretaceous ocean acidification triggered by massive volcanism
Large-igneous-province volcanic activity during the mid-Cretaceous triggered a global-scale episode of reduced marine oxygen levels known as Oceanic Anoxic Event 2 approximately 94.5 million years ago. It has been hypothesized that this geologically rapid degassing of volcanic carbon dioxide altered seawater carbonate chemistry, affecting marine ecosystems, geochemical cycles and sedimentation. Here we report on two sites drilled by the International Ocean Discovery Program offshore of southwest Australia that exhibit clear evidence for suppressed pelagic carbonate sedimentation in the form of a stratigraphic interval barren of carbonate minerals, recording ocean acidification during the event. We then use the osmium isotopic composition of bulk sediments to directly link this protracted ~600 kyr shoaling of the marine calcite compensation depth to the onset of volcanic activity. This decrease in marine pH was prolonged by biogeochemical feedbacks in highly productive regions where elevated heterotrophic respiration added carbon dioxide to the water column. A compilation of mid-Cretaceous marine stratigraphic records reveals a contemporaneous decrease of sedimentary carbonate content at continental slope sites globally. Thus, we contend that changes in marine carbonate chemistry are a primary ecological stress and important consequence of rapid emission of carbon dioxide during many large-igneous-province eruptions in the geologic past.Volcanic activity led to ocean acidification at the onset of Oceanic Anoxic Event 2, which then persisted for 600,000 years due to biogeochemical feedbacks, according to marine osmium isotope and carbonate sedimentation records offshore from southwest Australia.
A conceptual model for unbiased calculations of invertebrate abundances from freeze core samples
Freeze coring is a commonly used method for the investigation of the bed sediment fauna of rivers. It is considered to produce quantitative numbers of invertebrate abundance in different depth layers. Calculations of abundance use total volume of the freeze core sample as spatial reference. This definition of sample volume is incorrect. In the present, study freeze core samples are shown to consist of two parts: (1) a cylindrical inner core in which the pore water has turned into ice and (2) all parts of sediment, which protrude from this inner core. Invertebrates are fixed only within the inner core since the protruding parts contain no pores and therefore no invertebrate habitat. In samples from gravel rivers, the protruding parts form a considerable bias, which depends on the size of the core and the coarseness of the sediment. In the present study, total volume of individual core segments varied between 97 and 248% of actual sample volume. The inner core can be measured directly to avoid the bias. The procedure is proposed for future studies to produce unbiased, comparable values of invertebrate abundance and consequently reliable data on vertical distribution.