Model-independent approach to eta -> pi+ pi- gamma and eta' -> pi+ pi- gamma

We present a new, model-independent method to analyze radiative decays of mesons to a vector, isovector pair of pions of invariant mass square below the first significant pion-pion threshold in the vector channel. It is based on a combination of chiral perturbation theory and dispersion theory. This allows for a controlled inclusion of resonance physics without the necessity to involve vector meson dominance explicitly. As an example, the method is applied to an analysis of the reactions eta -> pi+ pi- gamma and eta'->pi+ pi- gamma.Comment: 16 pages, 4 figure

Ballistic electron microscopy and spectroscopy of metal and semiconductor nanostructures

Ballistic electron emission microscopy (BEEM) and its spectroscopy utilize ballistic transport of hot carriers as a versatile tool to characterize nanometer-scale structural and electronic properties of metallic and semiconducting materials and their interfaces. In this review, recent progress in experimental and theoretical aspects of the BEEM technique are covered. Emphasis is drawn to the development of BEEM in several emerging fields, including spin-sensitive hot-carrier transport through ferromagnetic thin films and multilayers, hot-electron spectroscopy and imaging of organic thin films and molecules, and hot-electron induced electroluminescence in semiconductor heterostructures. A brief discussion on BEEM of cross-sectional semiconductor heterostructures and advanced insulator films is also included

Theorizing resilience-building in the EU's neighbourhood: introduction to the special issue

The EU is surrounded by areas of limited statehood (ALS) and contested orders (CO) in its southern and eastern neighbourhood. Resilience has become a focus of attention in the academic debate on how to successfully deal with ALS and CO. Moreover, resilience-building is a new cornerstone in the EU's foreign and security policy. However, to what extent is resilience a mechanism to cope with ALS and CO? What are the sources of resilience? To what extent does the EU act as a resilience builder or spoiler in its neighbourhood? By presenting a new conceptual framework for analysing the interplay between risks, resilience, and governance breakdown/violent conflict as well as through in-depth empirical evidence, this special issue puts forward three key arguments. First, resilience is a key mechanism to prevent governance breakdown and violent conflict in the EU's neighbourhood. Second, three sources are key in building resilience: Social trust within societies and communities, legitimacy of (state and non-state) governance actors and institutions, as well as effective, fair, and inclusive governance institutions. Third, if external actors, such as the EU, seek to build resilience, they need to factor in long-time horizons, in-depth local knowledge, and a clearly designed strategy

Deterministic and Stochastic Dynamics of COVID-19: The Case Study of Italy and Spain

In December 2019, a severe respiratory syndrome (COVID-19) caused by a new coronavirus (SARS-CoV-2) was identified in China and spread rapidly around the globe. COVID-19 was declared a pandemic by the World Health Organization (WHO) in March 2020. With eventually substantial global underestimation, more than 225 million cases were confirmed by the end of August 2021, counting more than 4.5 million deaths. COVID-19 symptoms range from mild (or no symptoms) to severe illness, with disease severity and death occurring according to a hierarchy of risks, with age and preexisting health conditions enhancing the risks of disease severity manifestation. In this paper, a mathematical model for COVID-19 transmission is proposed and analyzed. The model stratifies the studied population into two groups, older and younger. Applied to the COVID-19 outbreaks in Spain and in Italy, we find the disease-free equilibrium and the basic reproduction number for each case study. A sensitivity analysis to identify the key parameters which influence the basic reproduction number, and hence regulate the transmission dynamics of COVID-19, is also performed. Finally, the model is extended to its stochastic counterpart to encapsulate the variation or uncertainty found in the transmissibility of the disease. We observe the variability of the infectious population finding its distribution at a given time, demonstrating that for small populations, stochasticity will play an important role.Marie Skłodowska-Curie grant agreement No. 79249

Dispersive analysis for η→γγ∗\eta\to \gamma\gamma^*

A dispersion integral is derived that connects data on $\eta\to \pi^+\pi^-\gamma$ to the $\eta\to \gamma\gamma^*$ transition form factor. A detailed analysis of the uncertainties is provided. We find for the slope of the $\eta$ transition form factor at the origin $b_\eta = (2.05 {}^{+0.22}_{-0.10})\, {\rm GeV}^{-2}$. Using an additional, plausible assumption, one finds for the corresponding slope of the $\eta'$ transition form factor, $b_{\eta'} = (1.58 {}^{+0.15}_{-0.08})\, {\rm GeV}^{-2}$. Both values are consistent with all recent data, but differ from some previous theoretical analyses.Comment: 11 pages, 3 figures, 2 tables (with extended discussion of the isoscalar contribution to the transition form factor

Stability of Whole Blood Lactate Specimens at Room Temperature Versus Slushed Ice Conditions

BackgroundThere are limited data on lactate stability in whole blood. The purpose of this study was to determine whole blood lactate stability at room temperature and in slushed ice conditions.MethodsAn equal number of arterial and venous samples were obtained from 202 subjects hospitalized for various pathophysiological conditions. Whole blood lactate concentration was measured over 5 different times spanning 80-90 min in a blood gas lab at a major hospital center. Samples were stored at room temperature (22-24°C) or in slushed ice conditions (0.1-0.2°C) before analysis.ResultsThe mean increase in lactate concentration was 0.001 mmol/L/min in samples on slushed ice over 90 min. However, at room temperature conditions, the mean increase in lactate concentration was 0.008 mmol/L/min regardless of whether the sample was arterial or venous. An increase in whole blood lactate concentration of ≥ 0.4 mmol/L occured after 45 min at room temperature, with 5% of all whole blood specimens demonstrating a meaningful change at ≤ 20 min. The ≥ 0.4 mmol/L change in whole blood lactate is considered significant based on the College of American Pathologists instrument peer-group standards.ConclusionsConsidering that a change in whole blood lactate concentration of ≥ 0.4 mmol/L is unacceptable instrument peer-group variation as defined by the College of American Pathologists, ice is no longer needed to stabilize whole blood lactate specimens when the draw time to analyze time is < 45 min. Samples remain stable even at 90 min when left on ice

Manipulation of subsurface carbon nanoparticles in Bi2Sr2CaCu2O8+δ using a scanning tunneling microscope

We present evidence that subsurface carbon nanoparticles in Bi2Sr2CaCu2O8+δ can be manipulated with nanometer precision using a scanning tunneling microscope. High-resolution images indicate that most of the carbon particles remain subsurface after transport observable as a local increase in height as the particle pushes up on the surface. Tunneling spectra in the vicinity of these protrusions exhibit semiconducting characteristics with a band gap of approximately 1.8 eV, indicating that the incorporation of carbon locally alters the electronic properties near the surface