A geochronological review of magmatism along the external margin of Columbia and in the Grenville-age orogens forming the core of Rodinia

A total of 4344 magmatic U-Pb ages in the range 2300 to 800 Ma have been compiled from the Great Proterozoic Accretionary Orogen along the margin of the Columbia / Nuna supercontinent and from the subsequent Grenvillian collisional orogens forming the core of Rodinia. The age data are derived from Laurentia (North America and Greenland, n = 1212), Baltica (NE Europe, n = 1922), Amazonia (central South America, n = 625), Kalahari (southern Africa and Dronning Maud Land in East Antarctica, n = 386), and western Australia (n = 199). Laurentia, Baltica, and Amazonia (and possibly other cratons) most likely formed a ca. 10 000-km-long external active continental margin of Columbia from its assembly at ca. 1800 Ma until its dispersal at ca. 1260 Ma, after which all cratons studied were involved in the Rodinia-forming Grenvillian orogeny. However, the magmatic record is not smooth and even but highly irregular, with marked peaks and troughs, both for individual cratons and the combined data set. Magmatic peaks typically range in duration from a few tens of million years up to around hundred million years, with intervening troughs of comparable length. Some magmatic peaks are observed on multiple cratons, either by coincidence or because of paleogeographic proximity and common tectonic setting, while others are not. The best overall correlation, 0.617, is observed between Baltica and Amazonia, consistent with (but not definitive proof of) their being close neighbours in a SAMBA-like configuration at least in Columbia, and perhaps having shared the same peri-Columbian subduction system for a considerable time. Correlation factors between Laurentia and Baltica, or Laurentia and Amazonia, are below 0.14. Comparison between the Grenville Province in northeastern Laurentia and the Sveconorwegian Province in southwestern Fennoscandia (Baltica) shows some striking similarities, especially in the Mesoproterozoic, but also exhibits differences in the timing of events, especially during the final Grenville-Sveconorwegian collision, when the Sveconorwegian evolution seems to lag behind by some tens of million years. Between the other cratons, the evolution before and during the final Grenvillian collision is also largely diachronous. After 900 Ma, magmatic activity had ceased in all areas investigated, attesting to the position of most of them within the stable interior of Rodinia.publishedVersio

Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run

Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society

Upstream-downstream benefit analysis of policy on water use by upstream tree plantations

This study focuses on the problem of water use by new upstream commercial tree plantations where fully-committed water entitlements are already held and traded among downstream sectors (urban water, wetlands and agricultural industries). High tree product prices strongly incentivise expansion of upstream plantation areas, particularly if there is no accounting for the predictable extra interception and use of water by trees. Planters could benefit greatly at the expense of downstream water users. Plotting this in a public-private benefit framework (PPBF) suggests a policy of “flexible negative incentives” to limit expansion of new trees, rather than ‘across the board’ banning of new plantations. We explore the ‘flexible’ option and the current ‘no control’ option for a case-study area, the Macquarie River catchment in central- west NSW, Australia, using three scenario sets: (1) Policy setting — without or with the requirement for distributions of water use entitlements to be handled by extending the existing downstream market to new upstream plantations (the flexible negative incentive). (2) Expected tree-product values — four exogenous levels ($40,$50, $60 or$70/m3), provide positive incentives for establishing trees. (3) Water quality — FRESH or a hypothetical SALTY scenario where one of six up- stream watersheds seeps so much salt into the river that water for urban use is compromised when new plantations reduce fresh water yields from the other five. We estimate quantitative consequences of all 16 combinations of the above scenarios, and show how an extended water market can deliver “flexible incentives” for efficient water distributions in which all new upstream and old downstream users either benefit by trading or remain unaffected

The performance of a 5 metre normal incidence monochromator at the Daresbury Laboratory Synchrotron Radiation Source

Available from British Library Document Supply Centre- DSC:6609.025(DL/SCI/P--638E) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Supply Chain Management Sales Using XCSR

The Trading Agent Competition in its category Supply Chain Management (TAC SCM) is an international forum where teams construct agents that control a computer assembly company in a simulated environment. TAC SCM involves the following problems: to determine when to send offers, to determine final sales prices of offered goods and to plan factory and delivery schedules. The main goal of this work was to develop an agent called TicTACtoe, using Wilson’s XCSR classifier system to decide the final sales prices. We develop an adaptation to the classifier system, that we called blocking classifiers technique, which allows the use of XCSR in an environment with parallel learning. Our results show that XCSR learning allows generating a set of rules that solves the TAC SCM sales problem in a satisfactory way. Moreover, we found that the blocking mechanism improves the performance of the XCSR learning in an environment with parallel learning