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The American Association of Physicists in Medicine (AAPM) is a nonprofit professional society whose primary purposes are to advance the science, education, and professional practice of medical physics. The AAPM has more than 8000 members and is the principal organization of medical physicists in the United States. The AAPM will periodically define new practice guidelines for medical physics practice to help advance the science of medical physics and to improve the quality of service to patients throughout the United States. Existing medical physics practice guidelines will be reviewed for the purpose of revision or renewal, as appropriate, on their fifth anniversary or sooner. Each medical physics practice guideline represents a policy statement by the AAPM, has undergone a thorough consensus process in which it has been subjected to extensive review, and requires the approval of the Professional Council. The medical physics practice guidelines recognize that the safe and effective use of diagnostic and therapeutic radiology requires specific training, skills, and techniques, as described in each document. Reproduction or modification of the published practice guidelines and technical standards by those entities not providing these services is not authorized. The following terms are used in the AAPM practice guidelines: Must and Must Not: Used to indicate that adherence to the recommendation is considered necessary to conform to this practice guideline. While must is the term to be used in the guidelines, if an entity that adopts the guideline has shall as the preferred term, the AAPM considers that must and shall have the same meaning. Should and Should Not: Used to indicate a prudent practice to which exceptions may occasionally be made in appropriate circumstances.

A geologically rapid Neoproterozoic oxygenation event is commonly linked to the appearance of marine animal groups in the fossil record. However, there is still debate about what evidence from the sedimentary geochemical record—if any—provides strong support for a persistent shift in surface oxygen immediately preceding the rise of animals. We present statistical learning analyses of a large dataset of geochemical data and associated geological context from the Neoproterozoic and Palaeozoic sedimentary record and then use Earth system modelling to link trends in redox-sensitive trace metal and organic carbon concentrations to the oxygenation of Earth’s oceans and atmosphere. We do not find evidence for the wholesale oxygenation of Earth’s oceans in the late Neoproterozoic era. We do, however, reconstruct a moderate long-term increase in atmospheric oxygen and marine productivity. These changes to the Earth system would have increased dissolved oxygen and food supply in shallow-water habitats during the broad interval of geologic time in which the major animal groups first radiated. This approach provides some of the most direct evidence for potential physiological drivers of the Cambrian radiation, while highlighting the importance of later Palaeozoic oxygenation in the evolution of the modern Earth system. Oxygen in shallow shelf waters rose linearly with atmospheric oxygen in the Neoproterozoic era, potentially driving the first radiation of marine animals, but widespread ocean oxygenation came later, according to reconstructions of oxygen levels and marine productivity.

Layered Cr-chalcogenides compounds offer a rich range of crystal phases with different magnetic properties some of which have been predicted only but not experimentally verified. Here we demonstrate a previously unreported crystal phase of CrS2, namely the distorted octahedral (1T\\('\\)) structure, synthesized via metal-organic chemical vapour deposition (MOCVD). We achieved the tuneable synthesis of either 1T\\('\\) or 1T phase CrS2. The structure were identified using polarized Raman spectroscopy, density functional perturbation theory (DFPT), as well as scanning electron diffraction (4D-STEM). 4D-STEM reveals that 1T\\('\\) crystals grow from an originally nucleated kinetically favoured 1T phase which then transform into the thermodynamically stable 1T\\('\\) phase. Magneto-optic Kerr imaging reveals that the 1T\\('\\) CrS2 crystals have soft ferromagnetic nature at low temperature. Our MOCVD growth of complex phases of 2D CrS2 with long-range magnetic order paves the way for the scalable synthesis of 2D magnets for ultrathin magnetic memories for logic-in-memory applications and spintronics.

Intro -- Contents -- Preface -- Introduction: Betting on Biotech -- 1. From Mitigating Risk to Managing Uncertainty -- 2. Reorganizing the State -- 3. Organizing Bio-industry -- 4. Manufacturing \"Progress\" -- 5. Regulatory Uncertainty -- Conclusion: Beyond the Developmental State -- Index.

Salmonella enterica serotype Typhimurium ( S . Typhimurium) causes acute gut inflammation by using its virulence factors to invade the intestinal epithelium and survive in mucosal macrophages. The inflammatory response enhances the transmission success of S . Typhimurium by promoting its outgrowth in the gut lumen through unknown mechanisms. Here we show that reactive oxygen species generated during inflammation react with endogenous, luminal sulphur compounds (thiosulphate) to form a new respiratory electron acceptor, tetrathionate. The genes conferring the ability to use tetrathionate as an electron acceptor produce a growth advantage for S . Typhimurium over the competing microbiota in the lumen of the inflamed gut. We conclude that S . Typhimurium virulence factors induce host-driven production of a new electron acceptor that allows the pathogen to use respiration to compete with fermenting gut microbes. Thus the ability to trigger intestinal inflammation is crucial for the biology of this diarrhoeal pathogen. A gut pathogen gains an edge The ability of the enteric pathogen Salmonella enterica serotype Typhimurium to use tetrathionate as a terminal electron acceptor has been used in the laboratory as a convenient means of enriching growth media containing this bacterium for many years. Tetrathionate respiration was thought to have little importance during infection, but to come into its own in free-living bacteria in environments containing tetrathionate, such as soil or decomposing carcasses. Now a possible role has been identified for this metabolism during intestinal infection. Acute intestinal inflammation induced by S. enterica Typhimurium virulence factors is shown to be accompanied by production of oxygen radicals in the gut lumen as part of the immune response. These oxygen radicals oxidize thiosulphate, the end product of hydrogen-sulphide detoxification by enterocytes, to tetrathionate. The pathogen can then use tetrathionate respiration during growth in the inflamed intestine, allowing it to out-compete other microbes that rely on anaerobic fermentation. Salmonella enterica serotype Typhimurium causes acute gut inflammation, which promotes the growth of the pathogen through unknown mechanisms. It is now shown that the reactive oxygen species generated during inflammation react with host-derived sulphur compounds to produce tetrathionate, which the pathogen uses as a terminal electron acceptor to support its growth. The ability to use tetrathionate provides the pathogen with a competitive advantage over bacteria that lack this property.

Notch-Delta signaling is a fundamental cell-cell communication mechanism that governs the differentiation of many cell types. Most existing mathematical models of Notch-Delta signaling are based on a feedback loop between Notch and Delta leading to lateral inhibition of neighboring cells. These models result in a checkerboard spatial pattern whereby adjacent cells express opposing levels of Notch and Delta, leading to alternate cell fates. However, a growing body of biological evidence suggests that Notch-Delta signaling produces other patterns that are not checkerboard, and therefore a new model is needed. Here, we present an expanded Notch-Delta model that builds upon previous models, adding a local Notch activity gradient, which affects long-range patterning, and the activity of a regulatory microRNA. This model is motivated by our experiments in the ascidian Ciona intestinalis showing that the peripheral sensory neurons, whose specification is in part regulated by the coordinate activity of Notch-Delta signaling and the microRNA miR-124, exhibit a sparse spatial pattern whereby consecutive neurons may be spaced over a dozen cells apart. We perform rigorous stability and bifurcation analyses, and demonstrate that our model is able to accurately explain and reproduce the neuronal pattern in Ciona. Using Monte Carlo simulations of our model along with miR-124 transgene over-expression assays, we demonstrate that the activity of miR-124 can be incorporated into the Notch decay rate parameter of our model. Finally, we motivate the general applicability of our model to Notch-Delta signaling in other animals by providing evidence that microRNAs regulate Notch-Delta signaling in analogous cell types in other organisms, and by discussing evidence in other organisms of sparse spatial patterns in tissues where Notch-Delta signaling is active.

After World War II, several late-developing countries registered astonishingly high growth rates under strong state direction, making use of smart investment strategies, turnkey factories, and reverse-engineering, and taking advantage of the postwar global economic boom. Among these economic miracles were postwar Japan and, in the 1960s and 1970s, the so-called Asian Tigers-Singapore, South Korea, and Taiwan-whose experiences epitomized the analytic category of the \"developmental state.\"In Betting on Biotech, Joseph Wong examines the emerging biotechnology sector in each of these three industrial dynamos. They have invested billions of dollars in biotech industries since the 1990s, but commercial blockbusters and commensurate profits have not followed. Industrial upgrading at the cutting edge of technological innovation is vastly different from the dynamics of earlier practices in established industries.The profound uncertainties of life-science-based industries such as biotech have forced these nations to confront a new logic of industry development, one in which past strategies of picking and making winners have given way to a new strategy of throwing resources at what remain very long shots. Betting on Biotech illuminates a new political economy of industrial technology innovation in places where one would reasonably expect tremendous potential-yet where billion-dollar bets in biotech continue to teeter on the brink of spectacular failure.