Resolving the Ripples (and a Mine): High-Resolution Multibeam Survey of Martha\u27s Vineyard ONR Mine Burial Program Field Area

In an effort to better understand the coastal processes responsible for the burial and exposure of small objects on the seafloor, the Office of Naval Research is sponsoring the Mine Burial Program. Among the field areas chosen for this program is the site of the Martha\u27s Vineyard Coastal Observatory (MVCO), a permanent instrumented node in 12 m of water about 500 m off the southern shore of Martha?s Vineyard. In support of the ONR program, several site surveys of the MVCO area have been conducted (see Goff et al); here we report the result of the most recent of these surveys, a very high-resolution multibeam survey aimed at establishing a detailed base map for the region and providing a baseline from which subsequent surveys can measure seafloor change In late July we conducted a five day survey of an approximately 3 x 5 km area surrounding the MVCO node using a Reson 8125 focused multibeam sonar aboard the SAIC survey vessel Ocean Explorer. The 8125 is a newly developed multibeam sonar that operates at 455 kHz and uses dynamic focusing to compensate for the curvature of the wavefront in the near-field. By using a relatively long array, the system can achieve very high spatial resolution (0.5 degree beam width) and with the dynamic focusing, can operate in the near field. The real constraint on resolution using this system is the ability to position the soundings and thus three kinematic DGPS base stations were established on Martha?s Vineyard and three kinematic receivers were used on the survey vessel. The kinematic GPS positioning is also critical to the ability to do repeat surveys with an accuracy high enough to resolve small (less than 10 cm) seafloor changes. Also to aid in our ability to accurately position repeat surveys, divers jetted sonar reflectors into the seafloor to act as fiducials. A super high-resolution (4 m overlap) survey was conducted in a small area surrounding the MVCO node and mine burial sites, a slightly lower resolution survey (12 to 25 m overlap) in a box approximately 1 x 1 km surrounding the ?target box? and a lower resolution survey (25 to 40 m line overlap) in a 3 x 5 km region surrounding the 1 x 1 km box. The Reson 8125 produced approximately 1 gigabyte of data per hour. The bathymetric resolution we were able to achieve was beyond our expectations. The node site and all diver-emplaced reflectors were clearly identified Most amazingly, we are able to resolve fields of individual ripples that are less than 2 cm height. Of particular relevance to the mine burial program was our ability to resolve an instrumented mine that had been deployed earlier by NRL. This mine is buried in a scour depression and is only a few centimeters proud above the base of the depression

Atomistic simulations of adiabatic coherent electron transport in triple donor systems

A solid-state analogue of Stimulated Raman Adiabatic Passage can be implemented in a triple well solid-state system to coherently transport an electron across the wells with exponentially suppressed occupation in the central well at any point of time. Termed coherent tunneling adiabatic passage (CTAP), this method provides a robust way to transfer quantum information encoded in the electronic spin across a chain of quantum dots or donors. Using large scale atomistic tight-binding simulations involving over 3.5 million atoms, we verify the existence of a CTAP pathway in a realistic solid-state system: gated triple donors in silicon. Realistic gate profiles from commercial tools were combined with tight-binding methods to simulate gate control of the donor to donor tunnel barriers in the presence of cross-talk. As CTAP is an adiabatic protocol, it can be analyzed by solving the time independent problem at various stages of the pulse - justifying the use of time-independent tight-binding methods to this problem. Our results show that a three donor CTAP transfer, with inter-donor spacing of 15 nm can occur on timescales greater than 23 ps, well within experimentally accessible regimes. The method not only provides a tool to guide future CTAP experiments, but also illuminates the possibility of system engineering to enhance control and transfer times.Comment: 8 pages, 5 figure

Forensic Toxicology in Embalmed Human Remains

© Cranfield University 2021. All rights reserved. No part of this publication may be reproduced without the written permission of the copyright ownerWithin the human body, vitreous humour, cerebrospinal fluid and synovial fluid are all contained within anatomical compartments that, by virtue of their relative avascularity, provide considerable protection from contamination during the embalming process. Analysing samples taken from embalmed medical school cadavers, and using an entirely novel headspace GC/MS method, the concentration of formaldehyde in all three fluids is shown to be significantly less than has previously been assumed in the literature. Using a newly-developed LC/Q-ToF method, the stability of fifteen drugs of forensic interest in representative concentrations of formaldehyde is then reported. The study is prompted by the fact that United Kingdom nationals are dying abroad with increasing frequency. Following repatriation of their bodies, an autopsy may be undertaken before permission for a funeral is granted. Although toxicological screening may form an important part of the investigative processes, there exists a large degree of uncertainty surrounding the reactive nature of formaldehyde, the main constituent of embalming fluids, with substances commonly implicated in drug-related deaths. It is the case, therefore, that in repatriated bodies, all of which are routinely embalmed before leaving the country in which death occurred, the presence of formaldehyde can cause significant problems for the forensic toxicologist. Although a number of papers in the past twenty years have investigated the challenges of drug detection in embalmed tissues, they have largely examined the problem from the perspective of histological samples preserved in formalin. While some of this work has, by implication, considered the analysis of samples taken from embalmed bodies, no studies have addressed directly the specific problems arising in the toxicological analysis of embalmed and repatriated bodies. The studies reported within the thesis demonstrate that there is considerable merit in undertaking further work on the usefulness of these fluids in the toxicological analysis of embalmed and repatriated nationalsPh

Experimental Demonstration of Greenberger-Horne-Zeilinger Correlations Using Nuclear Magnetic Resonance

The Greenberger-Horne-Zeilinger (GHZ) effect provides an example of quantum correlations that cannot be explained by classical local hidden variables. This paper reports on the experimental realization of GHZ correlations using nuclear magnetic resonance (NMR). The NMR experiment differs from the originally proposed GHZ experiment in several ways: it is performed on mixed states rather than pure states; and instead of being widely separated, the spins on which it is performed are all located in the same molecule. As a result, the NMR version of the GHZ experiment cannot entirely rule out classical local hidden variables. It nonetheless provides an unambiguous demonstration of the "paradoxical" GHZ correlations, and shows that any classical hidden variables must communicate by non-standard and previously undetected forces. The NMR demonstration of GHZ correlations shows the power of NMR quantum information processing techniques for demonstrating fundamental effects in quantum mechanics.Comment: Latex2.09, 8 pages, 1 eps figur

Schumacher's quantum data compression as a quantum computation

An explicit algorithm for performing Schumacher's noiseless compression of quantum bits is given. This algorithm is based on a combinatorial expression for a particular bijection among binary strings. The algorithm, which adheres to the rules of reversible programming, is expressed in a high-level pseudocode language. It is implemented using $O(n^3)$ two- and three-bit primitive reversible operations, where $n$ is the length of the qubit strings to be compressed. Also, the algorithm makes use of $O(n)$ auxiliary qubits; however, space-saving techniques based on those proposed by Bennett are developed which reduce this workspace to $O(\sqrt{n})$ while increasing the running time by less than a factor of two.Comment: 37 pages, no figure

Learning to Swim: What Influences Success?

Swimming and water safety skills are important life skills, particularly in Australia, where aquatic activities are regularly enjoyed. Little research has been undertaken exploring children’s swimming and water safety skills, what level they can achieve, and what factors impact their ability to learn these skills. This study explores children aged 5-12 years who participated in the Australian Capital Territory Primary Schools Swim and Survive Program, 2009-2011. Children who were more likely to achieve higher levels were older, were female, attended private school, swam at least once a fortnight, had a swimming pool at home, or visited a public swimming pool. Those who were less likely were Aboriginal or Torres Strait Islander, had a negative experience, and swam less than once a fortnight

Understanding the attitudes and experiences of people living with potentially stigmatised long-term health conditions with respect to collecting and sharing health and lifestyle data

Background: The emerging landscape of patient-generated data (PGData) provides an opportunity to collect large quantities of information that can be used to develop our understanding of different health conditions and potentially improve the quality of life for those living with long-term health condition (LTHCs). If the potential benefits of PGData are to be realised, we need a better understanding of the psychological barriers and facilitators to the collection and beneficial sharing of health and lifestyle data. Due to the understudied role that stigma plays in sharing PGData, we explore the attitudes and experiences of those living with potentially stigmatised LTHCs with respect to collecting and sharing health and lifestyle data. Methods: This study used semi-structured interviews and a card sorting task to explore the attitudes and experiences of people living with potentially stigmatised LTHCs. Fourteen adult participants who reported having a range of conditions were recruited in England. Template analysis was used to analyse interview transcripts and descriptive statistics were used for the card sorting task. Results: The findings present four overarching themes: Preferences for collecting health and lifestyle data, Importance of anonymity, Expected use of data, and Sources of emotional support. Participants illustrated a general willingness to share health and lifestyle data; however, there were some notable differences in sharing experiences, varying both by information type and recipient group. Overall, participants did not identify health-related stigma as a barrier to collecting or sharing their personal health and lifestyle data. Conclusions: We outline a number of preferences that participants feel would encourage them to collect and share data more readily, which may be considered when developing data sharing tools for the future