78 research outputs found

    Source Dimensions in Ultrarelativistic Heavy Ion Collisions

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    Recent experiments on pion correlations, interpreted as interferometric measurements of the collision zone, are compared with models that distinguish a prehadronic phase and a hadronic phase. The models include prehadronic longitudinal expansion, conversion to hadrons in local kinetic equilibrium, and rescattering of the produced hadrons. We find that the longitudinal and outward radii are surprisingly sensitive to the algorithm used for two-body collisions. The longitudinal radius measured in collisions of 200 GeV/u sulfur nuclei on a heavy target requires the existence of a prehadronic phase which converts to the hadronic phase at densities around 0.8-1.0 GeV/fm3^3. The transverse radii cannot be reproduced without introducing more complex dynamics into the transverse expansion.Comment: RevTeX 3.0, 28 pages, 6 figures, not included, revised version, major change is an additional discussion of the classical two-body collision algorithm, a (compressed) postscript file of the complete paper including figures can be obtained from Authors or via anonymous ftp at ftp://ftp_int.phys.washington.edu/pub/herrmann/pisource.ps.

    Bodily tides near spin-orbit resonances

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    Spin-orbit coupling can be described in two approaches. The method known as "the MacDonald torque" is often combined with an assumption that the quality factor Q is frequency-independent. This makes the method inconsistent, because the MacDonald theory tacitly fixes the rheology by making Q scale as the inverse tidal frequency. Spin-orbit coupling can be treated also in an approach called "the Darwin torque". While this theory is general enough to accommodate an arbitrary frequency-dependence of Q, this advantage has not yet been exploited in the literature, where Q is assumed constant or is set to scale as inverse tidal frequency, the latter assertion making the Darwin torque equivalent to a corrected version of the MacDonald torque. However neither a constant nor an inverse-frequency Q reflect the properties of realistic mantles and crusts, because the actual frequency-dependence is more complex. Hence the necessity to enrich the theory of spin-orbit interaction with the right frequency-dependence. We accomplish this programme for the Darwin-torque-based model near resonances. We derive the frequency-dependence of the tidal torque from the first principles, i.e., from the expression for the mantle's compliance in the time domain. We also explain that the tidal torque includes not only the secular part, but also an oscillating part. We demonstrate that the lmpq term of the Darwin-Kaula expansion for the tidal torque smoothly goes through zero, when the secondary traverses the lmpq resonance (e.g., the principal tidal torque smoothly goes through nil as the secondary crosses the synchronous orbit). We also offer a possible explanation for the unexpected frequency-dependence of the tidal dissipation rate in the Moon, discovered by LLR

    Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

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    Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

    Structural and dynamic tailoring of hingeless/bearingless rotors

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    SIGLECopy held by FIZ Karlsruhe; available from UB/TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

    Cell biology of Paget's disease

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    Paget's disease is characterized by markedly increased osteoclast formation and bone resorption followed by excessive new bone formation. Osteoclasts in Paget's disease are increased both in number and size, contain paramyxoviral-like nuclear inclusions, and can have up to 100 nuclei per cell. Marrow culture studies have identified several abnormalities in osteoclast formation in Paget's disease. Osteoclast-like multinucleated cells formed more rapidly in marrow cultures from patients with Paget's disease, produced increased levels of interleukin-6 (IL-6), and expressed high levels of IL-6 receptors compared to normals. IL-6 levels were also increased in bone marrow and peripheral blood of patients with Paget's disease. In addition, osteoclast precursors from patients with Paget's disease are hyperresponsive to 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and calcitonin. The increased sensitivity of osteoclast precursors to 1,25(OH)2D3 is mediated through the vitamin D receptor (VDR), since 24-hydroxylase activity is also up-regulated at concentrations of 1,25(OH)2D3 that are one log less than that needed to induce 24-hydroxylase activity in osteoclast precursors from normals. However, VDR numbers and affinity for 1,25(OH)2D3 do not differ in osteoclast precursors from Paget's patients compared to those from normals. Synergistic interactions between cytokines such as IL-6 and 1,25(OH)2D3 also cannot explain the enhanced sensitivity of osteoclast precursors from patients with Paget's disease to 1,25(OH)2D3. Interestingly, coculture studies of osteoclast precursors and cells from the marrow microenvironment of patients with Paget's disease and normals have demonstrated that the marrow microenvironment is more osteoclastogenic than normal. Thus, studies of the cell biology of osteoclasts in Paget's disease have demonstrated an increased rate of osteoclast formation and abnormalities in both osteoclast precursors and the marrow microenvironment. Enhanced IL-6 production by osteoclasts in Paget's disease may further amplify the increased osteoclast formation already ongoing in the pagetic lesion, and may explain the increased bone turnover at uninvolved sites distant from the pagetic lesion.SCOPUS: cp.jFLWINinfo:eu-repo/semantics/publishe
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