2,207 research outputs found

    Simulating Reionization: Character and Observability

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    In recent years there has been considerable progress in our understanding of the nature and properties of the reionization process. In particular, the numerical simulations of this epoch have made a qualitative leap forward, reaching sufficiently large scales to derive the characteristic scales of the reionization process and thus allowing for realistic observational predictions. Our group has recently performed the first such large-scale radiative transfer simulations of reionization, run on top of state-of-the-art simulations of early structure formation. This allowed us to make the first realistic observational predictions about the Epoch of Reionization based on detailed radiative transfer and structure formation simulations. We discuss the basic features of reionization derived from our simulations and some recent results on the observational implications for the high-redshift Ly-alpha sources.Comment: 3 pages, to appear in the Proceedings of First Stars III, Santa Fe, July 2007, AIP Conference Serie

    The Thermal Design, Characterization, and Performance of the SPIDER Long-Duration Balloon Cryostat

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    We describe the SPIDER flight cryostat, which is designed to cool six millimeter-wavelength telescopes during an Antarctic long-duration balloon flight. The cryostat, one of the largest to have flown on a stratospheric payload, uses liquid helium-4 to deliver cooling power to stages at 4.2 and 1.6 K. Stainless steel capillaries facilitate a high flow impedance connection between the main liquid helium tank and a smaller superfluid tank, allowing the latter to operate at 1.6 K as long as there is liquid in the 4.2 K main tank. Each telescope houses a closed cycle helium-3 adsorption refrigerator that further cools the focal planes down to 300 mK. Liquid helium vapor from the main tank is routed through heat exchangers that cool radiation shields, providing negative thermal feedback. The system performed successfully during a 17 day flight in the 2014-2015 Antarctic summer. The cryostat had a total hold time of 16.8 days, with 15.9 days occurring during flight.Comment: 15 pgs, 17 fig

    Developing an international concept-based curriculum for pharmacology education: The promise of core concepts and concept inventories

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    \ua9 2023 The Authors. British Journal of Clinical Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.Over recent years, studies have shown that science and health profession graduates demonstrate gaps in their fundamental pharmacology knowledge and ability to apply pharmacology concepts in practice. This article reviews the current challenges faced by pharmacology educators, including the exponential growth in discipline knowledge and competition for curricular time. We then argue that pharmacology education should focus on essential concepts that enable students to develop beyond ‘know’ towards ‘know how to’. A concept-based approach will help educators prioritize and benchmark their pharmacology curriculum, facilitate integration of pharmacology with other disciplines in the curriculum, create alignment between universities and improve application of pharmacology knowledge to professional contexts such as safe prescribing practices. To achieve this, core concepts first need to be identified and unpacked, and methods for teaching and assessment using concept inventories developed. The International Society for Basic and Clinical Pharmacology Education Section (IUPHAR-Ed) Core Concepts of Pharmacology (CCP) initiative involves over 300 educators from the global pharmacology community. CCP has identified and defined the core concepts of pharmacology, together with key underpinning sub-concepts. To realize these benefits, pharmacology educators must develop methods to teach and assess core concepts. Work to develop concept inventories is ongoing, including identifying student misconceptions of the core concepts and creating a bank of multiple-choice questions to assess student understanding. Future work aims to develop and validate materials and methods to help educators embed core concepts within curricula. Potential strategies that educators can use to overcome factors that inhibit adoption of core concepts are presented

    The Human Fungal Pathogen Cryptococcus neoformans Escapes Macrophages by a Phagosome Emptying Mechanism That Is Inhibited by Arp2/3 Complex-Mediated Actin Polymerisation

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    The lysis of infected cells by disease-causing microorganisms is an efficient but risky strategy for disseminated infection, as it exposes the pathogen to the full repertoire of the host's immune system. Cryptococcus neoformans is a widespread fungal pathogen that causes a fatal meningitis in HIV and other immunocompromised patients. Following intracellular growth, cryptococci are able to escape their host cells by a non-lytic expulsive mechanism that may contribute to the invasion of the central nervous system. Non-lytic escape is also exhibited by some bacterial pathogens and is likely to facilitate long-term avoidance of the host immune system during latency. Here we show that phagosomes containing intracellular cryptococci undergo repeated cycles of actin polymerisation. These actin ‘flashes’ occur in both murine and human macrophages and are dependent on classical WASP-Arp2/3 complex mediated actin filament nucleation. Three dimensional confocal imaging time lapse revealed that such flashes are highly dynamic actin cages that form around the phagosome. Using fluorescent dextran as a phagosome membrane integrity probe, we find that the non-lytic expulsion of Cryptococcus occurs through fusion of the phagosome and plasma membranes and that, prior to expulsion, 95% of phagosomes become permeabilised, an event that is immediately followed by an actin flash. By using pharmacological agents to modulate both actin dynamics and upstream signalling events, we show that flash occurrence is inversely related to cryptococcal expulsion, suggesting that flashes may act to temporarily inhibit expulsion from infected phagocytes. In conclusion, our data reveal the existence of a novel actin-dependent process on phagosomes containing cryptococci that acts as a potential block to expulsion of Cryptococcus and may have significant implications for the dissemination of, and CNS invasion by, this organism.\ud \u

    Do differences in profiling criteria bias performance measurements? Economic profiling of medical clinics under the Korea National Health Insurance program: An observational study using claims data

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    <p>Abstract</p> <p>Background</p> <p>With a greater emphasis on cost containment in many health care systems, it has become common to evaluate each physician's relative resource use. This study explored the major factors that influence the economic performance rankings of medical clinics in the Korea National Health Insurance (NHI) program by assessing the consistency between cost-efficiency indices constructed using different profiling criteria.</p> <p>Methods</p> <p>Data on medical care benefit costs for outpatient care at medical clinics nationwide were collected from the NHI claims database. We calculated eight types of cost-efficiency index with different profiling criteria for each medical clinic and investigated the agreement between the decile rankings of each index pair using the weighted kappa statistic.</p> <p>Results</p> <p>The exclusion of pharmacy cost lowered agreement between rankings to the lowest level, and differences in case-mix classification also lowered agreement considerably.</p> <p>Conclusions</p> <p>A medical clinic may be identified as either cost-efficient or cost-inefficient, even when using the same index, depending on the profiling criteria applied. Whether a country has a single insurance or a multiple-insurer system, it is very important to have standardized profiling criteria for the consolidated management of health care costs.</p

    Regulation of Pacing Strategy during Athletic Competition

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    Background: Athletic competition has been a source of interest to the scientific community for many years, as a surrogate of the limits of human ambulatory ability. One of the remarkable things about athletic competition is the observation that some athletes suddenly reduce their pace in the mid-portion of the race and drop back from their competitors. Alternatively, other athletes will perform great accelerations in mid-race (surges) or during the closing stages of the race (the endspurt). This observation fits well with recent evidence that muscular power output is regulated in an anticipatory way, designed to prevent unreasonably large homeostatic disturbances. Principal Findings: Here we demonstrate that a simple index, the product of the momentary Rating of Perceived Exertion (RPE) and the fraction of race distance remaining, the Hazard Score, defines the likelihood that athletes will change their velocity during simulated competitions; and may effectively represent the language used to allow anticipatory regulation of muscle power output. Conclusions: These data support the concept that the muscular power output during high intensity exercise performance is actively regulated in an anticipatory manner that accounts for both the momentary sensations the athlete is experiencing as well as the relative amount of a competition to be completed

    A review of information flow diagrammatic models for product-service systems

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    A product-service system (PSS) is a combination of products and services to create value for both customers and manufacturers. Modelling a PSS based on function orientation offers a useful way to distinguish system inputs and outputs with regards to how data are consumed and information is used, i.e. information flow. This article presents a review of diagrammatic information flow tools, which are designed to describe a system through its functions. The origin, concept and applications of these tools are investigated, followed by an analysis of information flow modelling with regards to key PSS properties. A case study of selection laser melting technology implemented as PSS will then be used to show the application of information flow modelling for PSS design. A discussion based on the usefulness of the tools in modelling the key elements of PSS and possible future research directions are also presented
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