Dynamical error bounds for continuum discretisation via Gauss quadrature rules, -- a Lieb-Robinson bound approach

Instances of discrete quantum systems coupled to a continuum of oscillators are ubiquitous in physics. Often the continua are approximated by a discrete set of modes. We derive analytical error bounds on expectation values of system observables that have been time evolved under such discretised Hamiltonians. These bounds take on the form of a function of time and the number of discrete modes, where the discrete modes are chosen according to Gauss quadrature rules. The derivation makes use of tools from the field of Lieb-Robinson bounds and the theory of orthonormal polynominals.Comment: 12 pages + 14 pages of proofs and appendices, Journal of Mathematical Physics, Vol.57, Issue 2 (2016) http://scitation.aip.org/content/aip/journal/jmp/57/2/10.1063/1.494043

Tracing the Distribution of Heavy Metals in Sediments of the Pearl River Estuary

The Pearl River Delta is the socio-economic hub of southern China. The region has experienced rapid industrialisation, particularly since the start of the Chinese Reform Programme in 1979. This rapid industrial development has been coupled with increased pressures on the natural environment environment from pollution and waste associated with this development. These pollutants are transported from within the Pearl River catchment and deposited in sediments of the Pearl River Estuary (PRE). Geospatial and principal component analysis of the heavy metals Al, Cd, Co, Cr, Cu, Fe, Ni, Pb, Ti and Zn in surface sediments identifies four patterns of spatial distribution that are attributed to three separate heavy metal sources. After normalisation for the effects of the fine particle size affinity, the same spatial distribution patterns remain, but with much less localised variability. Anticlockwise estuarine circulation and the interaction of marine and river water, where distributaries of the North and West Rivers enter the PRE, account for higher concentrations of all metals except Al in the west of the estuary. Pb and Zn are identified as the heavy metals displaying significant enrichment from non-natural sources. Their concentrations which peak at 168 and 699.9mg/Kg respectively along the North River, are found to be associated with higher baseline concentrations resulting from the erosion of metal sulphide bearing carbonates within the catchment. These higher baseline concentrations have then been further enriched by Galena (PbS) and Sphalerite (ZnS) mining operations, atmospheric deposition from fossil fuel burning and some point sources associated with urban and industrial waste. Temporal analysis of heavy metals and stable Pb isotope variability again highlights Pb and Zn as being significantly enriched from anthropogenic sources, with maximum enrichment factors of 2.6 and 1.8 respectively. The enrichment of these two metals is shown to begin in the 1950s and acceleration of their enrichment in the early 1990s. This second phase of enrichment in the 1990s is also associated with slight enrichment of Cr, Cu and Ni that is also attributed to anthropogenic sources

Performance of 2 1/4 Cr-1 Mo steel in a coal liquefaction dissolver vessel environment

Smooth-bar and notched-bar tensile specimens of bainitic 2 1/4 Cr-1 Mo steel were exposed with and without an applied stress to argon gas or to a coal slurry-H(,2) environment for various conditions of time, temperature and pressure. Room temperature mechanical properties determined after each coal slurry-H(,2) exposure were compared to those of like samples exposed to the same conditions in argon. The coal slurry exposures produced very little change in the room temperature mechanical properties even after 1000 hours at temperatures as high as 426(DEGREES)C and total pressures of 27.6 MPa;Corrosion samples were exposed in both the liquid phase and the gaseous phase above the coal slurry-H(,2) environment. Scale growth rates, electron microprobe analyses and X-ray analyses of the scale region were obtained;Smooth-bar and notched-bar tensile specimens of normalized and tempered (bainitic) 2 1/4 Cr-1 Mo steel were exposed to hydrogen gas at 5.2 to 27.6 MPa in the temperature range from 482(DEGREES) to 593(DEGREES)C. Exposed samples were in three conditions: unloaded, with an applied load, or lightly prestrained. Applied stress, plastic deformation and increasing exposure times all lowered the temperature, at any given pressure, for the formation of hydrogen attack bubbles. The results have been plotted on Nelson Curve coordinates;Fatigue crack growth tests were conducted on normalized and tempered (bainitic) 2 1/4 Cr-1 Mo steel. Crack growth rates were determined for near threshold to intermediate growth rate regions at room temperature and 427(DEGREES)C. Testing was done in a partial vacuum, moist air, hydrogen and coal slurry gases. Crack growth rates for various hydrogen pressures were examined. The results suggest that corrosion products of the coal slurry gases may mitigate the tendency of hydrogen to enhance fatigue crack growth. Possible mechanisms are suggested;J integral tests were performed to determine JIC on normalizedand tempered (bainitic) 2 1/4 Cr-1 Mo steel. J values were obtainedfrom deep cracked compact tension specimens using single andmultiple specimen techniques. Testing was carried out in vacuum,argon, hydrogen and coal slurry gases at 427(DEGREES)C. Single specimentests were made using an electropotential crack growthmeasurement system described in detail. Values of J(,IC) for the singlespecimen tests are compared to those obtained from the multiple;specimen tests;(\u271)DOE Report IS-T-1024. This work was performed under ContractW-7405-Eng-82 with the Department of Oil, Gas, and Energy

"New" and distributed leadership in quality and safety in healthcare, or "old" and hierarchical? : An interview study with strategic stakeholders

Peer reviewedPostprin

The friends and family test : a qualitative study of concerns that influence the willingness of English National Health Service staff to recommend their organisation

Peer reviewedPublisher PD

Episode 112: The Entangled Organism (with Sonia Sultan)

Does biological plasticity have a cost? Are there evolutionary consequences of plasticity and of organisms acting on their environments? In this episode, we talk with Sonia Sultan, the Alan M. Dachs Professor of Science in the Department of Biology at Wesleyan University. Sonia has spent her career studying the interplay between organisms and their environment. Specifically, she studies how environmental conditions influence the development of organisms, and when and how these developmental trajectories can include niche construction. Sonia refers to this complexity as “entanglement,” genes and environments working together to alter phenotypic expression, but then variation in phenotypic expression feeds back on environments and genes to alter evolution. She put this perspective to the test in a recent paper coauthored with Mike Wade in the Journal Evolution & Development. In it, Sonia and Mike took a new perspective on the Price equation, finding that niche construction and other forms of organismal agency can change evolutionary outcomes. Cover photo: Keating Shahmehrihttps://scholarworks.umt.edu/bigbiology_podcasts/1114/thumbnail.jp

Episode 095: Why are we like this? (with Tina Lasisi)

Why do humans look so different from one another? Why do we have different types of hair and different skin colors? And what do these traits have to do with the concept of race? On this episode, we talk with Tina Lasisi, incoming professor at the University of Michigan, about variation in human hair structure and skin color. We talk about why such variation may have evolved, and how biologists are studying it. We also discuss the implications of her work for the concept of race. Tina encourages scientists and the public to be curious about (rather than afraid of) human diversity, as it’s an obvious part of our world that should be understood from multiple perspectives, including biological. Cover photo: Keating Shahmehrihttps://scholarworks.umt.edu/bigbiology_podcasts/1096/thumbnail.jp

Episode 92: A journey into the brilliant abyss (with Helen Scales)

What hidden life lies at the bottom of the deep ocean? How do so many species survive and even thrive with so little light and food and at such pressure? In this episode, we talk to Helen Scales, a marine biologist, writer, and broadcaster who has written the essential guidebook to the deep ocean titled “The Brilliant Abyss,”. On our way to the bottom of the sea, Helen recounted her journey from academia to writing and shared some of the lessons for others looking to dive into science communication. She also introduced us to some of her favorite species and their unique adaptations for surviving at extreme depths as well as several threats that the deep ocean faces. Technology has not only opened up this ecosystem to exploration but also to exploitation. Helen lays out the current state of ocean conservation and offers some hope and advice to those looking to protect the planet\u27s largest habitat. Cover photo: Keating Shahmehrihttps://scholarworks.umt.edu/bigbiology_podcasts/1093/thumbnail.jp

Episode 088: How I learned to stop worrying and follow the data (with Timothy Caulfield)

How much coffee should we drink? Is there a scientific way to have a healthy, happy life? And how do we distinguish scientific sense from nonsense? In this episode, we talk with author and University of Alberta professor Timothy Caulfield about decision making and misinformation in the modern world. A surprising number of “common sense” decisions that people make in their daily lives are not actually backed by strong scientific evidence, and Tim strives to debunk these in his recent book, “Relax, Dammit!: A User\u27s Guide to the Age of Anxiety”. Among other things, we discuss with Tim how often we should check email and how risky it really is for kids to walk to school. We also talk about how science communication can be used to curb misinformation, and Tim shares his dos and don’ts for effective scicomm.https://scholarworks.umt.edu/bigbiology_podcasts/1089/thumbnail.jp

Episode 110: Tempest in a barcode: how rapidly can we (and should we) identify new species? (with Michael Sharkey)

How do biologists categorize species? What’s the best and quickest way to describe millions of unknown species? On this episode, we talk with Michael Sharkey, an entomologist and taxonomist who spent much of his career at the University of Kentucky, and is now the director of the Hymenoptera Institute. Since its inception, taxonomy has relied on careful morphological analysis of specimens to delineate species. In the past few decades, the COI “barcode” region of the mitochondrial genome has become a key additional piece of genetic evidence used to characterize species. In a much-discussed 2021 paper, Michael and colleagues used barcoding to identify over 400 new species of braconid wasps. The backlash from scientists who adhere to traditional taxonomic methods was swift, and at times harsh, with critics claiming that relying primarily on COI to define species is simply unacceptable. Sharkey, however, remains convinced that taxonomy should embrace molecular tools, especially because millions of species are yet to be discovered and rates of extinction are ramping up. We talk with Michael about how many insect species there are, how barcoding can make taxonomy accessible to more scientists, and what the future of taxonomy might look like. Cover photo: Keating Shahmehrihttps://scholarworks.umt.edu/bigbiology_podcasts/1112/thumbnail.jp