Fate of internal waves on a shallow shelf

Author Posting. © American Geophysical Union, 2020. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research: Oceans 125(5), (2020): e2019JC015377, doi:10.1029/2019JC015377.Internal waves strongly influence the physical and chemical environment of coastal ecosystems worldwide. We report novel observations from a distributed temperature sensing (DTS) system that tracked the transformation of internal waves from the shelf break to the surf zone over a narrow shelf slope region in the South China Sea. The spatially continuous view of temperature fields provides a perspective of physical processes commonly available only in laboratory settings or numerical models, including internal wave reflection off a natural slope, shoreward transport of dense fluid within trapped cores, and observations of internal rundown (near‐bed, offshore‐directed jets of water preceding a breaking internal wave). Analysis shows that the fate of internal waves on this shelf—whether transmitted into shallow waters or reflected back offshore—is mediated by local water column density structure and background currents set by the previous shoaling internal waves, highlighting the importance of wave‐wave interactions in nearshore internal wave dynamics.We are grateful for the support of the Dongsha Atoll Research Station (DARS) and the Dongsha Atoll Marine National Park, whose efforts made this research possible. The authors would also like to thank A. Hall, S. Tyler, and J. Selker from the Center for Transformative Environmental Monitoring Programs (CTEMPs) funded by the National Science Foundation (EAR awards 1440596 and 1440506), G. Lohmann from WHOI, A. Safaie from UC Irvine, G. Wong, L. Hou, F. Shiah, and K. Lee from Academia Sinica for providing logistical and field support, as well as E. Pawlak, S. Lentz, B. Sanders, and S. Grant for equipment, and B. Raubenheimer, S. Elgar, R. Walter and D. Lucas for informative discussions that improved this work. We acknowledge the US Army Research Laboratory DoD Supercomputing Resource Center for computer time on Excalibur, which was used for the numerical simulations in this work. Funding for this work supported by Academia Sinica and for K.D. and E.R. from NSF‐OCE 1753317 and for O.F., J.R., and R.A. from ONR Grant 1182789‐1‐TDZZM. A portion of this work (R.A.) was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE‐AC52‐07NA27344.2020-10-2

High frequency temperature variability reduces the risk of coral bleaching

Coral bleaching is the detrimental expulsion of algal symbionts from their cnidarian hosts, and predominantly occurs when corals are exposed to thermal stress. The incidence and severity of bleaching is often spatially heterogeneous within reef-scales (<1 km), and is therefore not predictable using conventional remote sensing products. Here, we systematically assess the relationship between in situ measurements of 20 environmental variables, along with seven remotely sensed SST thermal stress metrics, and 81 observed bleaching events at coral reef locations spanning five major reef regions globally. We find that high-frequency temperature variability (i.e., daily temperature range) was the most influential factor in predicting bleaching prevalence and had a mitigating effect, such that a 1 °C increase in daily temperature range would reduce the odds of more severe bleaching by a factor of 33. Our findings suggest that reefs with greater high-frequency temperature variability may represent particularly important opportunities to conserve coral ecosystems against the major threat posed by warming ocean temperatures

The Murchison Widefield Array: Design Overview

The Murchison Widefield Array (MWA) is a dipole-based aperture array synthesis telescope designed to operate in the 80-300 MHz frequency range. It is capable of a wide range of science investigations, but is initially focused on three key science projects. These are detection and characterization of 3-dimensional brightness temperature fluctuations in the 21cm line of neutral hydrogen during the Epoch of Reionization (EoR) at redshifts from 6 to 10, solar imaging and remote sensing of the inner heliosphere via propagation effects on signals from distant background sources,and high-sensitivity exploration of the variable radio sky. The array design features 8192 dual-polarization broad-band active dipoles, arranged into 512 tiles comprising 16 dipoles each. The tiles are quasi-randomly distributed over an aperture 1.5km in diameter, with a small number of outliers extending to 3km. All tile-tile baselines are correlated in custom FPGA-based hardware, yielding a Nyquist-sampled instantaneous monochromatic uv coverage and unprecedented point spread function (PSF) quality. The correlated data are calibrated in real time using novel position-dependent self-calibration algorithms. The array is located in the Murchison region of outback Western Australia. This region is characterized by extremely low population density and a superbly radio-quiet environment,allowing full exploitation of the instrumental capabilities.Comment: 9 pages, 5 figures, 1 table. Accepted for publication in Proceedings of the IEE

Ferritins: furnishing proteins with iron

Ferritins are a superfamily of iron oxidation, storage and mineralization proteins found throughout the animal, plant, and microbial kingdoms. The majority of ferritins consist of 24 subunits that individually fold into 4-α-helix bundles and assemble in a highly symmetric manner to form an approximately spherical protein coat around a central cavity into which an iron-containing mineral can be formed. Channels through the coat at inter-subunit contact points facilitate passage of iron ions to and from the central cavity, and intrasubunit catalytic sites, called ferroxidase centers, drive Fe2+ oxidation and O2 reduction. Though the different members of the superfamily share a common structure, there is often little amino acid sequence identity between them. Even where there is a high degree of sequence identity between two ferritins there can be major differences in how the proteins handle iron. In this review we describe some of the important structural features of ferritins and their mineralized iron cores and examine in detail how three selected ferritins oxidise Fe2+ in order to explore the mechanistic variations that exist amongst ferritins. We suggest that the mechanistic differences reflect differing evolutionary pressures on amino acid sequences, and that these differing pressures are a consequence of different primary functions for different ferritins

Masses, radii, and orbits of small Kepler planets : The transition from gaseous to rocky planets

We report on the masses, sizes, and orbits of the planets orbiting 22 Kepler stars. There are 49 planet candidates around these stars, including 42 detected through transits and 7 revealed by precise Doppler measurements of the host stars. Based on an analysis of the Kepler brightness measurements, along with high-resolution imaging and spectroscopy, Doppler spectroscopy, and (for 11 stars) asteroseismology, we establish low false-positive probabilities (FPPs) for all of the transiting planets (41 of 42 have an FPP under 1%), and we constrain their sizes and masses. Most of the transiting planets are smaller than three times the size of Earth. For 16 planets, the Doppler signal was securely detected, providing a direct measurement of the planet's mass. For the other 26 planets we provide either marginal mass measurements or upper limits to their masses and densities; in many cases we can rule out a rocky composition. We identify six planets with densities above 5 g cm-3, suggesting a mostly rocky interior for them. Indeed, the only planets that are compatible with a purely rocky composition are smaller than 2 R ⊕. Larger planets evidently contain a larger fraction of low-density material (H, He, and H2O).Peer reviewedFinal Accepted Versio

Updated protocol and guest participant results from the ACCeRT clinical study

Introduction Cancer cachexia is a condition often seen at diagnosis, throughout chemotherapeutic treatments and in end stage Non-Small Cell Lung Cancer patients. These patients often experience a shorter life-expectancy and deterioration in performance status and reduced quality of life. New multi˗targeted regimens are required to be tested in this population to address these issues. Materials and methods The ACCeRT study is an open label, prospective, randomised controlled feasibility study investigating the use of eicosapentaenoic acid and COX-2 inhibitor (celecoxib) versus eicosapentaenoic acid, COX-2 inhibitor (celecoxib), progressive resistance training followed by ingestion of essential amino acids high in leucine in Non-Small Cell Lung Cancer cachectic patients. The study protocol was published in November 2011. Due to study participants and study team preferences a number of changes were made. Firstly, a change from a bolus drink containing 20 g of essential amino acids to an encapsulated form in divided doses over three days. Secondly, a change in leg strength analysis from utilising a leg/back dynamometry to a customised chair with a load cell testing extension isometric force. Thirdly, study drug dose reductions were now permitted. Fourthly, addition of two study sites which allowed participants to attend progressive resistance training sessions in their local area. Finally, a change in inclusion criteria to include participants that had received any first-line anti-cancer treatment. A guest participant was invited onto the study in April 2012, followed by the first study participant in June 2012. Results The guest participant showed trends in efficacy in a number of outcomes; stable fat free mass in the context of decreasing total body weight, with stable FAACT˗PWB, MFSI-SF physical, and WHOQOL-BREF QOL scores at week 20, all during documented disease progression now termed refractory cachexia. There were no treatment or exercise-related adverse events. Conclusion Publishing feasibility study protocols allows transparency in study interventions and assessments. The above ACCeRT regimen stabilised fat free mass and a number of physical/performance indicators and QOL in the guest participant

A multi-targeted treatment approch to cancer cachexia: Auckland's Cancer Cachexia evaluating Resistance Training (ACCeRT) trial

Abstract Background Cancer cachexia is a condition often seen at diagnosis, throughout anti-cancer treatments and in end-stage nonsmall- cell lung cancer patients. Methods and results Participants with late-stage non-small-cell lung cancer and cachexia (defined as ≥5% weight loss within 12 months) were randomly assigned 1:2 to 2.09 g of eicosapentaenoic acid (EPA) and 300 mg of cyclo-oxygenase-2 inhibitor celecoxib orally once daily vs. same dosing of EPA, celecoxib, plus two sessions per week of progressive resistance training and 20 g of oral essential amino acids high in leucine in a split dose over 3 days, after each session. Primary endpoint was the acceptability of the earlier multi-targeted approach. Main secondary endpoints included change in body weight and fat-free mass, by bioelectric impedance analysis and total quadriceps muscle volume by magnetic resonance imaging over 20 weeks. Sixty-nine patients were screened resulting in 20 patients being enrolled. Acceptability scored high, with 4.5/5 (Arm A) and 5/5 (Arm B) for EPA and 5/5 for celecoxib within both arms and 4.8/5 for progressive resistance training sessions and 4.5/5 for essential amino acids within Arm B, all at Week 20. Results showed a net gain in bioelectric impedance analysis fat-free mass of +1.3 kg, n = 2 (Arm A), compared with +0.7 kg, n = 7 (Arm B) at Week 12, and —1.5 kg, n = 2 (Arm A), compared with —1.7 kg, n = 4 (Arm B) at Week 20. Trends in efficacy in terms of improvement and/or stability in cachexia markers were seen within magnetic resonance imaging muscle volume, albumin, and C-reactive protein levels within both arms. There were no exercise-related adverse events, with one possible related adverse event of asymptomatic atrial fibrillation in one participant within Arm A. Conclusions Non-small-cell lung cancer cachectic patients are willing to be enrolled onto a multi-targeted treatment regimen and may benefit from cachexia symptom management even during the late/refractory stage

Detection of intrinsic source structure at ~3 Schwarzschild radii with Millimeter-VLBI observations of SAGITTARIUS A*

We report results from very long baseline interferometric (VLBI) observations of the supermassive black hole in the Galactic center, Sgr A*, at 1.3 mm (230 GHz). The observations were performed in 2013 March using six VLBI stations in Hawaii, California, Arizona, and Chile. Compared to earlier observations, the addition of the APEX telescope in Chile almost doubles the longest baseline length in the array, provides additional {\it uv} coverage in the N-S direction, and leads to a spatial resolution of $\sim$30 $\mu$as ($\sim$3 Schwarzschild radii) for Sgr A*. The source is detected even at the longest baselines with visibility amplitudes of $\sim$4-13% of the total flux density. We argue that such flux densities cannot result from interstellar refractive scattering alone, but indicate the presence of compact intrinsic source structure on scales of $\sim$3 Schwarzschild radii. The measured nonzero closure phases rule out point-symmetric emission. We discuss our results in the context of simple geometric models that capture the basic characteristics and brightness distributions of disk- and jet-dominated models and show that both can reproduce the observed data. Common to these models are the brightness asymmetry, the orientation, and characteristic sizes, which are comparable to the expected size of the black hole shadow. Future 1.3 mm VLBI observations with an expanded array and better sensitivity will allow a more detailed imaging of the horizon-scale structure and bear the potential for a deep insight into the physical processes at the black hole boundary.Comment: 11 pages, 5 figures, accepted to Ap