The timing and duration of the Delamerian orogeny: Correlation with the Ross Orogen and implications for Gondwana assembly

Copyright © 2006 by the University of Chicago PressThe Antarctic Ross and the Australian Delamerian orogenies are the consequence of stress transfer to the outboard trailing edge of the newly assembled Gondwana supercontinent. This tectonic reorganization occurred in the Early to Middle Cambrian on completion of Pan-African deformation and subduction along the sutures between eastern and western Gondwanan continental fragments. Before this, Neoproterozoic to Early Cambrian rocks in eastern Australia were formed in a passive margin and record dispersion of Rodinia with consequent opening of the proto-Pacific. Our new U-Pb and Rb-Sr geochronology shows that in the South Australian (Adelaide Fold Belt) domain of the Delamerian Orogen, contractional orogenesis commenced at 514 ± 3 Ma and persisted for ∼24 m.yr. until 490 ± 3 Ma, terminated by rapid uplift, cooling, and extension in association with posttectonic magmatism. Integration of new and published U-Pb and 40Ar-39Ar geochronology from the entire Ross-Delamerian belt shows that although both the Delamerian and Ross have a synchronous late magmatic and terminal cooling history, the Ross commenced its convergent orogenic history at ∼540 Ma. This was 25 m.yr. before Delamerian deformation began. During the Early Cambrian, eastern Australia was still in a state of extension (or transtension), with opening of the Kanmantoo Basin and associated anorogenic, largely mafic magmatism. This basin received sediment from the already exposed Ross Orogen to the south. The simultaneous first occurrence of strain fabrics and subduction-related magmatism (including boninite, granite, and andesite lavas) at ∼514 Ma in New Zealand, Victoria, South Australia, New South Wales, and Tasmania implies that the Delamerian Orogeny was driven by ridge-push forces transmitted on the initiation of westward-dipping subduction. Subsequent eastward slab rollback at 490 Ma may have occurred when the new slab had reached the transition zone at 650-km depth, resulting in upper plate extension and anorogenic Basin and Range–style magmatism in South Australia and Tasmania (Mount Read belt). The delayed onset of subduction in the Australian sector of the margin implies that westward motion of the Australian portion of eastern Gondwana continued to be accommodated during the late Early Cambrian by subduction or deformation along either the Mozambique Suture or at the northern end of the South Prince Charles Mountains–Prydz Bay suture.John Foden, Marlina A. Elburg, Jon Dougherty-Page, and Andrew Burt

Prebiotic synthesis of cysteine peptides that catalyze peptide ligation in neutral water

Peptide biosynthesis is performed by ribosomes and several other classes of enzymes, but a simple chemical synthesis may have created the first peptides at the origins of life. a-Aminonitriles—prebiotic a–amino acid precursors—are generally produced by Strecker reactions. However, cysteine’s aminothiol is incompatible with nitriles. Consequently, cysteine nitrile is not stable, and cysteine has been proposed to be a product of evolution, not prebiotic chemistry. We now report a high-yielding, prebiotic synthesis of cysteine peptides. Our biomimetic pathway converts serine to cysteine by nitrile-activated dehydroalanine synthesis. We also demonstrate that N-acylcysteines catalyze peptide ligation, directly coupling kinetically stable—but energy-rich—a-amidonitriles to proteinogenic amines. This rare example of selective and efficient organocatalysis in water implicates cysteine as both catalyst and precursor in prebiotic peptide synthesis

Snake orbits and related magnetic edge states

We study the electron motion near magnetic field steps at which the strength and/or sign of the magnetic field changes. The energy spectrum for such systems is found and the electron states (bound and scattered) are compared with their corresponding classical paths. Several classical properties as the velocity parallel to the edge, the oscillation frequency perpendicular to the edge and the extent of the states are compared with their quantum mechanical counterpart. A class of magnetic edge states is found which do not have a classical counterpart.Comment: 8 pages, 10 figure

Mattrygghet i Europa: en kartlegging av kritiske matpraksiser og kulturelle forskjeller i Frankrike, Norge, Portugal, Romania og Storbritannia

How is food handled in safe and unsafe ways from retail to fork in European households? This is the overall research question raised in this report. The aim of this report is to contribute to an in-depth, detailed, empirical and nuanced analysis of how food is handled in everyday life in five European countries: France, Norway, Portugal, Romania and the UK. The first chapters (Part 1) describe the food cultural difference and food safety variation between the five countries, theories of practices that underpin the study and the transdisciplinary methods employed for studying shopping, transportation, storage and cooking a meal with chicken and raw vegetables in 75 European households. The first empirical chapters (Part 2) introduce the households in this study (chapter 2.1), discuss the everyday food life the households (chapter 2.2) and describe food anxieties and experiences with foodborne illnesses (chapter 2.3). Part 3 concentrates on food procuring and organising practices in the households and includes three empirical discussions of shopping (chapter 3.1), transportation (chapter 3.2) and storage (chapter 3.3). Part 4 discusses food preparation and comprises five chapters discussing the order of cooking (chapter 4.1), chicken preparation (chapter 4.2), vegetable preparation (chapter 4.3), determining doneness (chapter 4.4) and washing hands (chapter 4.5). Finally, Part 5 discusses the main findings in the report and suggests further research steps.info:eu-repo/semantics/publishedVersio

Fano resonances in a three-terminal nanodevice

The electron transport through a quantum sphere with three one-dimensional wires attached to it is investigated. An explicit form for the transmission coefficient as a function of the electron energy is found from the first principles. The asymmetric Fano resonances are detected in transmission of the system. The collapse of the resonances is shown to appear under certain conditions. A two-terminal nanodevice with an additional gate lead is studied using the developed approach. Additional resonances and minima of transmission are indicated in the device.Comment: 11 pages, 5 figures, 2 equations are added, misprints in 5 equations are removed, published in Journal of Physics: Condensed Matte

Suitability versus fidelity for rating single-photon guns

The creation of specified quantum states is important for most, if not all, applications in quantum computation and communication. The quality of the state preparation is therefore an essential ingredient in any assessment of a quantum-state gun. We show that the fidelity, under the standard definitions is not sufficient to assess quantum sources, and we propose a new measure of suitability that necessarily depends on the application for the source. We consider the performance of single-photon guns in the context of quantum key distribution (QKD) and linear optical quantum computation. Single-photon sources for QKD need radically different properties than sources for quantum computing. Furthermore, the suitability for single-photon guns is discussed explicitly in terms of experimentally accessible criteria.Comment: 4 pages, 2 figures Revised per referee suggestion

Environment or Economy? Food Concerns and Sustainable Food Transitions in the UK

Recent years have seen the emergence of calls for the transformation of food systems to make these more responsive to environmental, access and health challenges. Addressing how the UK food system may best meet these challenges, this article develops understanding of the multiple food concerns that guide practices of food provisioning at the intersection between markets and domestic life. Combining insights from a survey questionnaire and qualitative fieldwork from research that was part of the EU Horizon2020 SafeConsume project, we depict how practices of food provisioning are guided by concerns driven by economic and environmental logics. The findings suggest economy is prevalent while environmental food ethics are marginalised. The conclusion discusses how the adopted practice theoretical approach, which combines an analysis of the socio-material arrangements of provisioning and the relationship between food concerns and higher order considerations, advances understanding of the nature of food concerns and the challenges of sustainable food transitioning. </jats:p

Two-dimensional electron gas in a linearly varying magnetic field: Quantization of the electron and current density

Published versio

Relationships between speed, change of direction and jump performance with cricket specific speed tests in male academy cricketers

Objectives: The aim of this study was to investigate the relationships between general speed and change of direction speed and‘cricket specific’ speed tests and the relationships between jump performance and speed and change of direction ability in male academy cricketers. Design and Methods: Sixteen academy male cricketers (age: 17 ± 0.7 years; height: 176.9 ± 6.2 cm; mass: 72.2 ± 13.2 kg) performed tests of 20 m sprint, 505 change of direction (COD) on both left and right legs, “quick single” with bat (WB) (17.68m), running-a-two WB, running-a-three WB, countermovement jump (CMJ), and drop jump (DJ). Results: Intra-class correlation coefficients (ICC’s) revealed high within-session reliability for all tests (ICC ≥ 0.92; p ≤ 0.001),except 0-5 m (ICC = 0.642; p ≤ 0.001) and 0-10 m (ICC = 0.708; p ≤ 0.001) tests. General speed tests showed strong relationships to ‘cricket specific’ speed tests (20 m sprint - running-a-two; r = 0.951; p ≤ 0.01; 20 m sprint - running-a-three; r = 0.937; p ≤ 0.01; ‘quick single’; r = 0.951; p ≤ 0.01). Strong relationships were also observed between the 505 right foot COD times and all cricket specific tests (r = 0.909- 0.934; p ≤ 0.01). CMJ height showed the strongest correlations with: 20 m (r = -0.668;p ≤ 0.01); 505 left (r = -0.789; p ≤ 0.01); 505 right (r = -0.807; p ≤ 0.01); “quick single” WB (r = -0.739; p ≤ 0.01); running-a two WB (r = -0.742; p ≤ 0.01); running-a-three (WB) (r = -0.733; p ≤ 0.01). Conclusions: The findings suggest that general speed and COD tests are highly appropriate to assess cricket specific qualities in youth cricketers