Simulating the Role of Axial Flow in Stay Cable Vibrations via a Perforated Wake Splitter Plate”, ASCE Special Edition: Wind Engineering in Natural Hazards

Cable-stayed bridges have become progressively popular since 1955, mainly because of their modest requirement on ground anchorage condition, efficient use of structural material, higher stiffness, and economy compared to suspension bridges. The inclined and/or yawed orientation of bridge stay cables results in the formation of secondary axial flow on the leeward side of cable surface, which is believed to be one of the contributing factors exciting some unique wind-induced cable vibration phenomena. To clarify the role of axial flow in triggering aerodynamic instability of stay cables, a numerical study has been conducted to indirectly examine the axial flow effect via a perforated splitter plate placed along the central line of a circular cylinder wake. Results show that the presence of a perforated wake splitter plate would play a similar role as the axial flow in affecting the strength of von Kármán vortex shedding. Reductions on the fluctuating amplitude of the instantaneous lift and drag, as well as the mean drag, are also observed, which would ultimately affect the aerodynamic response of the studied cylinder

Infection control in dental health care during and after the SARS-CoV-2 outbreak

COVID-19 is an emerging infectious disease caused by the widespread transmission of the coronavirus SARS-CoV-2. Some of those infected become seriously ill. Others do not show any symptoms, but can still contribute to transmission of the virus. SARS-CoV-2 is excreted in the oral cavity and can be spread via aerosols. Aerosol generating procedures in dental health care can increase the risk of transmission of the virus. Due to the risk of infection of both dental healthcare workers and patients, additional infection control measures for all patients are strongly recommended when providing dental health care. Consideration should be given to which infection control measures are necessary when providing care in both the current situation and in the future

Multi-Species Test of Ion Cyclotron Resonance Heating at High Altitudes

Observations of ion distributions and plasma waves obtained by the Dynamics Explorer 1 satellite in the high-altitude, nightside auroral zone are used to study ion energization for three ion species. A number of theoretical models have been proposed to account for the transverse heating of these ion populations. One of these, the ion cyclotron resonance heating (ICRH) mechanism, explains ion conic formation through ion cyclotron resonance with broadband electromagnetic wave turbulence in the vicinity of the characteristic ion cyclotron frequency. The cyclotron resonant heating of the ions by low-frequency electromagnetic waves is an important energy source for the transport of ions from the ionosphere to the magnetosphere. In this paper we test the applicability of the ICRH mechanism to three simultaneously heated and accelerated ion species by modelling the ion conic formation in terms of a resonant wave-particle interaction in which the ions extract energy from the portion of the broadband electromagnetic wave spectrum which includes the ion cyclotron frequency. Using a Monte Carlo technique we evaluate the ion heating produced by the electromagnetic turbulence at low frequencies and find that the wave amplitudes near the ion cyclotron frequencies are sufficient to explain the observed ion energies

Multi-Species Test of Ion Cyclotron Resonance Heating at High Altitudes

Observations of ion distributions and plasma waves obtained by the Dynamics Explorer 1 satellite in the high-altitude, nightside auroral zone are used to study ion energization for three ion species. A number of theoretical models have been proposed to account for the transverse heating of these ion populations. One of these, the ion cyclotron resonance heating (ICRH) mechanism, explains ion conic formation through ion cyclotron resonance with broadband electromagnetic wave turbulence in the vicinity of the characteristic ion cyclotron frequency. The cyclotron resonant heating of the ions by low- frequency electromagnetic waves is an important energy source for the transport of ions from the ionosphere to the magnetosphere. In this paper we test the applicability of the ICRH mechanism to three simultaneously heated and accelerated ion species by modelling the ion conic formation in terms of a resonant wave-particle interaction in which the ions extract energy from the portion of the broadband electromagnetic wave spectrum which includes the ion cyclotron frequency. Using a Monte Carlo technique we evaluate the ion heating produced by the electromagnetic turbulence at low frequencies and find that the wave amplitudes near the ion cyclotron frequencies are sufficient to explain the observed ion energies

Forty years of Leiden environmental science: the history of the Leiden Institute of Environmental Sciences (CML) 1978-2018

Forty years of Leiden environmental sciences relates the story of CML, today one of the Faculty of Science’s eight institutes but with its roots in a more or less in dependent group of ex-activists within the university. Back in the day, many of those at the top of the university would probably have had trouble accepting that ‘those upstarts’ would still be around forty years on – not locked away in some cubbyhole with their stencil duplicator, but as a professor, assistant professor or even a dean. Today they are professors emeritus or have retired: Helias Udo de Haes, Wouter de Groot, Gerard Barendse, Gjalt Huppes, Gerard Persoon, Hans de Iongh and Jan Boersema – which doesn’t stop most of them just carrying on working. And a new generation of environmental scientists is now leading CML’s research and teaching: Geert de Snoo, Arnold Tukker, Martina Vijver, Peter van Bodegom, Jeroen Guinée, Ester van der Voet and René Kleijn.Industrial EcologyConservation Biolog

Control of Jupiter's radio emission and aurorae by the solar wind

Radio emissions from Jupiter provided the first evidence that this giant planet has a strong magnetic field(1,2) and a large magnetosphere(3). Jupiter also has polar aurorae(4), which are similar in many respects to Earth's aurorae(5). The radio emissions are believed to be generated along the high-latitude magnetic field lines by the same electrons that produce the aurorae, and both the radio emission in the hectometric frequency range and the aurorae vary considerably(6,7). The origin of the variability, however, has been poorly understood. Here we report simultaneous observations using the Cassini and Galileo spacecraft of hectometric radio emissions and extreme ultraviolet auroral emissions from Jupiter. Our results show that both of these emissions are triggered by interplanetary shocks propagating outward from the Sun. When such a shock arrives at Jupiter, it seems to cause a major compression and reconfiguration of the magnetosphere, which produces strong electric fields and therefore electron acceleration along the auroral field lines, similar to the processes that occur during geomagnetic storms at the Earth.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/62740/1/415985a.pd

Coordinate and redox interactions of epinephrine with ferric and ferrous iron at physiological pH

Coordinate and redox interactions of epinephrine (Epi) with iron at physiological pH are essential for understanding two very different phenomena - the detrimental effects of chronic stress on the cardiovascular system and the cross-linking of catecholamine-rich biopolymers and frameworks. Here we show that Epi and Fe3+ form stable high-spin complexes in the 1:1 or 3:1 stoichiometry, depending on the Epi/Fe3+ concentration ratio (low or high). Oxygen atoms on the catechol ring represent the sites of coordinate bond formation within physiologically relevant bidentate 1:1 complex. Redox properties of Epi are slightly impacted by Fe3+. On the other hand, Epi and Fe2+ form a complex that acts as a strong reducing agent, which leads to the production of hydrogen peroxide via O-2 reduction, and to a facilitated formation of the Epi-Fe3+ complexes. Epi is not oxidized in this process, i.e. Fe2+ is not an electron shuttle, but the electron donor. Epi-catalyzed oxidation of Fe2+ represents a plausible chemical basis of stress-related damage to heart cells. In addition, our results support the previous findings on the interactions of catecholamine moieties in polymers with iron and provide a novel strategy for improving the efficiency of cross-linking.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3040

A critical review of the research literature on Six Sigma, Lean and StuderGroup's Hardwiring Excellence in the United States: the need to demonstrate and communicate the effectiveness of transformation strategies in healthcare

<p>Abstract</p> <p>Background</p> <p>U.S. healthcare organizations are confronted with numerous and varied transformational strategies promising improvements along all dimensions of quality and performance. This article examines the peer-reviewed literature from the U.S. for evidence of effectiveness among three current popular transformational strategies: Six Sigma, Lean/Toyota Production System, and Studer's Hardwiring Excellence.</p> <p>Methods</p> <p>The English language health, healthcare management, and organizational science literature (up to December 2007) indexed in Medline, Web of Science, ABI/Inform, Cochrane Library, CINAHL, and ERIC was reviewed for studies on the aforementioned transformation strategies in healthcare settings. Articles were included if they: appeared in a peer-reviewed journal; described a specific intervention; were not classified as a pilot study; provided quantitative data; and were not review articles. Nine references on Six Sigma, nine on Lean/Toyota Production System, and one on StuderGroup meet the study's eligibility criteria.</p> <p>Results</p> <p>The reviewed studies universally concluded the implementations of these transformation strategies were successful in improving a variety of healthcare related processes and outcomes. Additionally, the existing literature reflects a wide application of these transformation strategies in terms of both settings and problems. However, despite these positive features, the vast majority had methodological limitations that might undermine the validity of the results. Common features included: weak study designs, inappropriate analyses, and failures to rule out alternative hypotheses. Furthermore, frequently absent was any attention to changes in organizational culture or substantial evidence of lasting effects from these efforts.</p> <p>Conclusion</p> <p>Despite the current popularity of these strategies, few studies meet the inclusion criteria for this review. Furthermore, each could have been improved substantially in order to ensure the validity of the conclusions, demonstrate sustainability, investigate changes in organizational culture, or even how one strategy interfaced with other concurrent and subsequent transformation efforts. While informative results can be gleaned from less rigorous studies, improved design and analysis can more effectively guide healthcare leaders who are motivated to transform their organizations and convince others of the need to employ such strategies. Demanding more exacting evaluation of projects consultants, or partnerships with health management researchers in academic settings, can support such efforts.</p