Implosion in the Challenger Deep: echo sounding with the shock wave

© The Author(s), 2021. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Loranger, S., Barclay, D., & Buckingham, M. Implosion in the Challenger Deep: echo sounding with the shock wave. Oceanography, 34(2), (2021), https://doi.org/10.5670/oceanog.2021.201.Since HMS Challenger made the first sounding in the Mariana Trench in 1875, scientists and explorers have been seeking to establish the exact location and depth of the deepest part of the ocean. The scientific consensus is that the deepest depth is situated in the Challenger Deep, an abyss in the Mariana Trench with depths greater than 10,000 m. Since1952, when HMS Challenger II, following its namesake, returned to the Mariana Trench, 20 estimates (including the one from this study) of the depth of the Challenger Deep have been made. The location and depth estimates are as diverse as the methods used to obtain them; they range from early measurements with explosives and stopwatches, to single- and multibeam sonars, to submersibles, both crewed and remotely operated. In December 2014, we participated in an expedition to the Challenger Deep onboard Schmidt Ocean Institute’s R/V Falkor and deployed two free-falling, passive-acoustic instrument platforms, each with a glass-sphere pressure housing containing system electronics. At a nominal depth of 9,000 m, one of these housings imploded, creating a highly energetic shock wave that, as recorded by the other instrument, reflected multiple times from the sea surface and seafloor. From the arrival times of these multi-path pulses at the surviving instrument, in conjunction with a concurrent measurement of the sound speed profile in the water column, we obtained a highly constrained acoustic estimate of the Challenger Deep: 10,983 ± 6 m.This work was funded by the Schmidt Ocean Institute, the Ocean Frontiers Institute, and the Office of Naval Research, Ocean Acoustics, Code 322OA, grant number N00014-18-1-2126

Optimising patient care in medical radiation services through health economics: an introduction

The role of health economics in optimising patient care in medical radiation clinical settings is of increasing importance in ensuring efficient and effective service delivery. This commentary introduces health economics to medical radiation professionals by outlining the main analysis types utilised, highlighted by examples in the literature. The purpose is to provide an over-arching framework and starting point for incorporating health economics into medical radiation research study protocols

Signal regulatory protein alpha (SIRPα) regulates the homeostasis of CD103⁺CD11b⁺ DCs in the intestinal lamina propria

Signal regulatory protein alpha (SIRP alpha/CD172a) is a conserved transmembrane protein thought to play an inhibitory role in immune function by binding the ubiquitous ligand CD47. SIRP alpha expression has been used to identify dendritic cell subsets across species and here we examined its expression and function on intestinal DCs in mice. Normal mucosa contains four subsets of DCs based on their expression of CD103 and CD11b and three of these express SIRP alpha. However, loss of SIRP alpha signaling in mice leads to a selective reduction in the CD103(+)CD11b(+) subset of DCs in the small intestine, colon, and amongmigratory DCs in the mesenteric lymph node. In parallel, these mice have reduced numbers of T(H)17 cells in steady-state intestinal mucosa, and a defective T(H)17 response to Citrobacter infection. Identical results were obtained in CD47KO mice. DC precursors from SIRP alpha mutant mice had an enhanced ability to generate CD103(+)CD11b(+) DCs in vivo, but CD103(+)CD11b(+) DCs from mutant mice were more prone to die by apoptosis. These data show a previously unappreciated and crucial role for SIRP alpha in the homeostasis of CD103(+)CD11b(+) DCs in the intestine, as well as providing further evidence that this subset of DCs is critical for the development of mucosal T(H)17 responses

Charge pair dissociation and recombination dynamics in a P3HT–PC60BM bulk heterojunction

The authors thank the EPSRC, SUPA, the Condensed Matter Doctoral Training Centre and the European Union Seventh Framework programme (grant agreement 321305) for financial support.The mechanism by which Coulombically bound charge pairs dissociate into free carriers in photovoltaic donor–acceptor blends is of great interest. Here, we use polarization-sensitive transient absorption (TA) to study the diffusion of photogenerated holes in a polythiophene (P3HT)–fullerene (PC60BM) blend. We observe an initial anisotropy value of 0.4 for the absorption of photogenerated holes, indicating that holes generated on a 100 fs time scale are localized on the same polymer chain as their precursor excitons. Depolarization dynamics indicate fast initial hole motion on a 0.3 ps time scale and slower migration up to 100 ps. Charge pair recombination is found to occur on a much longer time scale of 10–1000 ns via a purely bimolecular process independent of excess energy. Our results show that nearly all charge pairs get separated by at least 7 nm in the absence of an external field and indicate that high charge mobility is crucial for charge separation.PostprintPeer reviewe

Evaluation of Indigenous justice programs Project D. Safe Aboriginal Youth Patrol programs in New South Wales and Northbridge policy and Juvenile Aid Group in Western Australia

In this evaluation, we examined two different approaches to delivery of Community and Night patrol services for young people: the Safe Aboriginal Youth Patrol programs (SAYP) of NSW, and the Northbridge Policy project (NPP) sometimes also called the Young people in Northbridge project, in Perth, Western Australia. The overarching focus of this evaluation was to determine whether the programs should be considered as examples of ‘good practice’ to be replicated elsewhere, and to find evidence of outcomes achieved by each program..

Mental Optometry: The Mind’s Eye, You Go Where You’re Looking

The term, Mental Optometry, is newly developed concept that can be used to describe the interplay between mind, brain, and sensory interpretations. Taken from the premise of behavioral optometry and research explaining body orientation to physical field of vision, what we see or perceive with our mind’s eye, emotions and behaviors will also follow in the same manner. While not explicitly referred to in such a manner, cognitive, cognitive behavioral, and cognitive bias formation theories imply such a concept as being foundational to their systems. Mental Optometry arms the theorist and practitioner with a neurobiological empowered understanding of mood, emotion, thought, and interpretations of visual stimuli such that therapeutic interventions can be developed to assist patients in recognizing and altering skewed interpretations of what they think they see (the mind’s eye) – imagery that may deleteriously support negative cognitions leading to negative mood states

A Pilot Study on the Effects of Exercise on Depression Symptoms Using Levels of Neurotransmitters and EEG as Markers

Context: The prescribing of exercise by physicians has become a popular practice, yet the effectiveness of exercise on symptoms of depression is difficult to determine due to a lack of randomized controlled trials with clinical populations. Reports also indicate that only a small percentage of physicians advise their patients regarding exercise and confusion still exists as to how much and what types are best. Aims: To understand the mechanisms that make exercise a viable treatment in depression. Settings and Design: This study employed a six‑week, two group, single‑level trial, pre‑ and posttest design using self‑report of symptoms, blood levels of serotonin, dopamine, epinephrine, and norepinephrine, and frontal slow wave EEG activity as markers. This study was registered with clinicaltrials.gov. ID# NCT02023281. Subjects and Methods: Eleven participants with a diagnosis of depression between the ages of 18 and 65 were enrolled from March 2013 through May 2013. Baseline and post‑intervention measures consisted of the Beck Depression Inventory‑II, blood serum levels of serotonin, catecholamines (epinephrine, norepinephrine, and dopamine), and mean alpha frequency. Statistical Analysis Used: A series of independent t‑tests for each dependent variable was conducted. Results: Independent t‑tests reveal significant between‑group differences in depression scores (P = 0.005, d = 2.23); F7 activity (P = 0.012, d = 1.92); and F8 activity (P = 0.04, d = 1.52). Conclusions: The results of this pilot study show that even mild to very moderate levels of exercise 2‑3 times per week consisting of alternating days of aerobic and strength resistance training can be effective in reducing symptoms of depression giving physicians concrete information for their patients on the prescription of exercise

Mechanical and hydrologic basis for the rapid motion of a large tidewater glacier: 1. Observations

Measurements of glacier flow velocity and basal water pressure at two sites on Columbia Glacier, Alaska, are combined with meteorological and hydrologic data to provide an observational basis for assessing the role of water storage and basal water pressure in the rapid movement of this large glacier. During the period from July 5 to August 31, 1987, coordinated observations were made of glacier surface motion and of water level in five boreholes drilled to (or in one case near to) the glacier bed at two sites, 5 and 12 km from the terminus. Glacier velocities increased downglacier in this reach from about 4 m d^−1 to about 7 m d^−1. Three types of time variation in velocity and other variables were revealed: (1) Diurnal fluctuation in water input/output, borehole water level, and ice velocity (fluctuation amplitude 5 to 8%); (2) Speed-up events in glacier motion (15–30% speed up), lasting about 3 days, and occurring at times of enhanced input of water, in some cases from rain and in others from ice ablation enhanced by strong, warm winds; (3) “Extra-slowdown” events, in which, after a speed-up event, the ice velocity decreased in about 3 days to a level consistently lower than that prior to the speed-up event. All of the time variations in velocity were due, directly or indirectly, to variations in water input to the glacier. The role of basal water in causing the observed glacier motions is interpreted by Kamb et al. (this issue)