Photoelectric emission from the alkali metal doped vacuum-ice interface

The photoelectron photoemission spectra and thresholds for low coverages of Li and K adsorbed on water-ice have been measured, compared with photoionization spectra of the gas-phase atoms, and modeled by quantum chemical calculations. For both alkali metals the threshold for photoemission is dramatically decreased and the cross section increased on adsorption to the water-ice surface. Quantum chemical calculations suggest that the initial state is formed by the metal atoms adsorbed into the water-ice surface, forming a state with a delocalized electron distribution. This state is metastable and decays on the hundreds of seconds time scale at 92 K. The decay is markedly faster for Li than for K, probably due to diffusion into the ice film

Impact of COVID-19 on cardiovascular testing in the United States versus the rest of the world

Objectives: This study sought to quantify and compare the decline in volumes of cardiovascular procedures between the United States and non-US institutions during the early phase of the coronavirus disease-2019 (COVID-19) pandemic. Background: The COVID-19 pandemic has disrupted the care of many non-COVID-19 illnesses. Reductions in diagnostic cardiovascular testing around the world have led to concerns over the implications of reduced testing for cardiovascular disease (CVD) morbidity and mortality. Methods: Data were submitted to the INCAPS-COVID (International Atomic Energy Agency Non-Invasive Cardiology Protocols Study of COVID-19), a multinational registry comprising 909 institutions in 108 countries (including 155 facilities in 40 U.S. states), assessing the impact of the COVID-19 pandemic on volumes of diagnostic cardiovascular procedures. Data were obtained for April 2020 and compared with volumes of baseline procedures from March 2019. We compared laboratory characteristics, practices, and procedure volumes between U.S. and non-U.S. facilities and between U.S. geographic regions and identified factors associated with volume reduction in the United States. Results: Reductions in the volumes of procedures in the United States were similar to those in non-U.S. facilities (68% vs. 63%, respectively; p = 0.237), although U.S. facilities reported greater reductions in invasive coronary angiography (69% vs. 53%, respectively; p < 0.001). Significantly more U.S. facilities reported increased use of telehealth and patient screening measures than non-U.S. facilities, such as temperature checks, symptom screenings, and COVID-19 testing. Reductions in volumes of procedures differed between U.S. regions, with larger declines observed in the Northeast (76%) and Midwest (74%) than in the South (62%) and West (44%). Prevalence of COVID-19, staff redeployments, outpatient centers, and urban centers were associated with greater reductions in volume in U.S. facilities in a multivariable analysis. Conclusions: We observed marked reductions in U.S. cardiovascular testing in the early phase of the pandemic and significant variability between U.S. regions. The association between reductions of volumes and COVID-19 prevalence in the United States highlighted the need for proactive efforts to maintain access to cardiovascular testing in areas most affected by outbreaks of COVID-19 infection

Seasonal variations of the Na and Fe layers at the South Pole and their implications for the chemistry and general circulation of the polar mesosphere

Lidar observations, conducted at the South Pole by University of Illinois researchers, are used to characterize the seasonal variations of mesospheric Na and Fe above the site. The annual mean layer abundances are virtually identical to midlatitude values, and the mean centroid height is just 100 m higher for Na and 450 m higher for Fe compared with 40 N. The most striking feature of the metal profiles is the almost complete absence of Na and Fe below 90 km during midsummer. This leads to summertime layers with significantly higher peaks, narrower widths, and smaller abundances than are observed at lower latitudes. The measurements are compared with detailed chemical models of these species that were developed at the University of East Anglia. The models accurately reproduce most features of these observations and demonstrate the importance of rapid uptake of the metallic species on the surfaces of polar mesospheric clouds and meteoric smoke particles. The models show that vertical downwelling in winter, associated with the meridional circulation system, must be less than about 1 cm s 1 in the upper mesosphere in order to avoid displacing the minor constituents O, H, and the metal layers too far below 85 km. They also show that an additional source of gas-phase metallic species, that is comparable to the meteoric input, is required during winter to correctly model the Na and Fe abundances. This source appears to arise from the wintertime convergence of the meridional flow over the South Pole.Ope

Photodesorption and photochemical dynamics on roughened silver: Sulphur dioxide and carbonyl sulphide

The photodesorption of SO2, both monolayer and multilayer, from roughened silver has been investigated. The photodesorption cross-section is enhanced by a factor of 2.6 +/- 0.4 compared to the Ag(111) surface. The peak in the enhancement occurs at 340 nm. Time-of-flight mass spectrometry shows that the same mechanism operates on both the rough and Ag(111) surfaces. Coverage dependent experiments show that the enhancement is a first layer phenomenon, and coverage of greater than one monolayer effectively suppresses photodesorption. These data point to a surface plasmon resonance enhanced substrate mediated (hot electron attachment) photodesorption mechanism. (c) 2005 Elsevier B.V. All rights reserved

Photoemission from sodium on ice: A mechanism for positive and negative charge coexistence in the mesosphere

Photoemission from sodium deposited on ice films is described. Deposition of 0.02 ML of sodium is found to dramatically reduce the threshold for photoemission from the ice film to (2.3 ( 0.2) eV. Thus, the cross-section for photoemission reaches&gt;10-18 cm2 in the visible region of the spectrum. It is proposed that the initial state is a solvated electron on the ice surface, which is supported by optical transmission spectroscopy. The potential significance of these results in understanding unexplained charging phenomena in the mesosphere is discussed

Exploring the Performance gap in EU Framework Programmes between EU13 and EU15 Member States. In-Depth Analysis

The research and innovation framework programmes of the European Union (EU) are the largest programmes in the world for international research collaboration. Repeated reports point to the issue of under-performance in the framework programmes by the EU13 Member States – the countries that joined the EU in and after 2004 – in comparison with the EU15 Member States – which had entered the EU before 2004. This paper explores the background of various challenges in research and development faced by the EU13 in comparison to the EU15, in order to investigate the gap between the two groups. A set of hypotheses, divided into five domains, are tested empirically. This includes research and innovation system structure; scientific level of research institutions and quality of proposals; quantity of submitted proposals; level of international collaboration and other factors related to the framework programmes. The weak positions of most EU13 Member States on several of the indicators analysed show that the field of research in EU13 Member States requires further structural changes. This report concludes with various policy options that would help to mitigate the innovation gap in Europe