The propagation of large, storm-generated waves through sea ice has so far not been measured, limiting our understanding of how ocean waves break sea ice. Without improved knowledge of ice breakup, ...we are unable to understand recent changes, or predict future changes, in Arctic and Antarctic sea ice. Here we show that storm-generated ocean waves propagating through Antarctic sea ice are able to transport enough energy to break sea ice hundreds of kilometres from the ice edge. Our results, which are based on concurrent observations at multiple locations, establish that large waves break sea ice much farther from the ice edge than would be predicted by the commonly assumed exponential decay. We observed the wave height decay to be almost linear for large waves--those with a significant wave height greater than three metres--and to be exponential only for small waves. This implies a more prominent role for large ocean waves in sea-ice breakup and retreat than previously thought. We examine the wider relevance of this by comparing observed Antarctic sea-ice edge positions with changes in modelled significant wave heights for the Southern Ocean between 1997 and 2009, and find that the retreat and expansion of the sea-ice edge correlate with mean significant wave height increases and decreases, respectively. This includes capturing the spatial variability in sea-ice trends found in the Ross and Amundsen-Bellingshausen seas. Climate models fail to capture recent changes in sea ice in both polar regions. Our results suggest that the incorporation of explicit or parameterized interactions between ocean waves and sea ice may resolve this problem.
Although there have been tremendous advances in the understanding of human dysfunctions in the brain circuitry for self-reflection, emotion, and cognitive control, a brain-based taxonomy for mental ...disease is still lacking. As a result, these advances have not been translated into actionable clinical tools, and the language of brain circuits has not been incorporated into training programmes. To address this gap, I present this synthesis of published work, with a focus on functional imaging of circuit dysfunctions across the spectrum of mood and anxiety disorders. This synthesis provides the foundation for a taxonomy of putative types of dysfunction, which cuts across traditional diagnostic boundaries for depression and anxiety and includes instead distinct types of neural circuit dysfunction that together reflect the heterogeneity of depression and anxiety. This taxonomy is suited to specifying symptoms in terms of underlying neural dysfunction at the individual level and is intended as the foundation for building mechanistic research and ultimately guiding clinical practice.
The field of quantum computing has grown from concept to demonstration devices over the past 20 years. Universal quantum computing offers efficiency in approaching problems of scientific and ...commercial interest, such as factoring large numbers, searching databases, simulating intractable models from quantum physics, and optimizing complex cost functions. Here, we present an 11-qubit fully-connected, programmable quantum computer in a trapped ion system composed of 13
Yb
ions. We demonstrate average single-qubit gate fidelities of 99.5Formula: see text, average two-qubit-gate fidelities of 97.5Formula: see text, and SPAM errors of 0.7Formula: see text. To illustrate the capabilities of this universal platform and provide a basis for comparison with similarly-sized devices, we compile the Bernstein-Vazirani and Hidden Shift algorithms into our native gates and execute them on the hardware with average success rates of 78Formula: see text and 35Formula: see text, respectively. These algorithms serve as excellent benchmarks for any type of quantum hardware, and show that our system outperforms all other currently available hardware.
Large public projects represent major complex investment and whilst there has been much written about how to develop, manage and deliver such projects, practice still does not match up with ...expectations. In this book, researchers from the Norwegian Concept Research Programme explore the paradoxes between theory and practice in collaboration with experts in the field of project governance. This book delves into the reality of large public projects, to show how they can be managed effectively and efficiently, recognising the realities of their context. It offers a range of practical conclusions as to the paradoxes of the governance and management of public projects. The international spectrum of authors draw their examples from the UK, Norway, Canada, France, Australia and the Netherlands. Bridging the gap between research, theory and practice, this book will benefit academics and researchers in the field of project management and corporate governance as well as those in the practice of public project governance, civil servants and industry practitioners.
ABSTRACT
Photometry at 3.4 and 4.6 ${\mu m}$ of 128 Population I WC type Wolf–Rayet stars in the Galaxy and 12 in the Large Magellanic Cloud (LMC) observed in the WISE NEOWISE-R survey was searched ...for evidence of circumstellar dust emission and its variation. Infrared spectral energy distributions (SEDs) were assembled, making use of archival r, i, Z, and Y photometry to determine reddening and stellar wind levels for the WC stars found in recent IR surveys and lacking optical photometry. From their SEDs, 10 apparently non-variable stars were newly identified as dust makers, including three, WR 102-22, WR 110-10, and WR 124-10, having subtype earlier than WC8–9, the first such stars to show this phenomenon. The 11 stars found to show variable dust emission include six new episodic dust makers, WR 47c, WR 75-11, WR 91-1, WR 122-14, and WR 125-1 in the Galaxy and HD 38030 in the LMC. Of previously known dust makers, NEOWISE-R photometry of WR 19 captured its rise to maximum in 2018 confirming the 10.1-yr period, that of WR 125 the beginning of a new episode of dust formation suggesting a period near 28.3 yr. while that of HD 36402 covered almost a whole period and forced revision of it to 5.1 yr.
ABSTRACT
Gravitational waves provide a unique tool for observational astronomy. While the first LIGO–Virgo catalogue of gravitational-wave transients (GWTC-1) contains 11 signals from black hole and ...neutron star binaries, the number of observations is increasing rapidly as detector sensitivity improves. To extract information from the observed signals, it is imperative to have fast, flexible, and scalable inference techniques. In a previous paper, we introduced bilby: a modular and user-friendly Bayesian inference library adapted to address the needs of gravitational-wave inference. In this work, we demonstrate that bilby produces reliable results for simulated gravitational-wave signals from compact binary mergers, and verify that it accurately reproduces results reported for the 11 GWTC-1 signals. Additionally, we provide configuration and output files for all analyses to allow for easy reproduction, modification, and future use. This work establishes that bilby is primed and ready to analyse the rapidly growing population of compact binary coalescence gravitational-wave signals.
In past years, a diagnosis of bronchiolitis obliterans syndrome (BOS) after allogeneic hematopoietic cell transplant (HCT) conferred nearly universal mortality secondary to lack of consensus for ...diagnostic criteria, poorly understood disease pathogenesis, and very few studies of therapeutic or supportive care interventions. Recently, however, progress has been made in these areas: revised consensus diagnostic guidelines are now available, supportive care has improved, there is greater understanding of potential mechanisms of disease, and prospective trials are being conducted. This article describes these advances and provides suggestions to optimize therapy for patients with BOS after HCT.
Amongst the many ways of constructing the amide bond, there has been a growing interest in the use of metal-catalysed methods for preparing this important functional group. In this tutorial review, ...highlights of the recent literature have been presented covering the key areas where metal catalysts have been used in amide bond formation. Acids and esters have been used in coupling reactions with amines, but aldehydes and alcohols have also been used in oxidative couplings. The use of nitriles and oximes as starting materials for amide formation are also emerging areas of interest. The use of carbon monoxide in the transition metal catalysed coupling of amines has led to a powerful methodology for amide bond formation and this is complemented by the addition of an aryl or alkenyl group to an amide typically using palladium or copper catalysts.