Recombination luminescence from defects in boron-ion implantation-doped diamond using low fluences

 Two identical, high purity, natural type IIa diamonds, which displayed the ubiquitous blue cathodoluminescence (CL) band at ≈ 2.9 eV, as well as an indication of the corresponding green band at ≈ 2.4 eV, have been equivalently doped by using extremely low dose B⁺- and C⁺-ion CIRA-implantations respectively. Comparative CL measurements showed changes in the intensities of the 2.9 and 2.4 eV bands and the generation of bands at ≈ 4 eV, as well as at ≈ 3.5 and ≈ 4.6 eV (the latter two in the B⁺-CIRA diamond). The results are commensurate with the model (proposed previously) in which the 2.9 and 4 eV bands are generated respectively by electron-hole recombinations at negatively charged acceptor- and positively charged donor-like, intrinsic defects. The present results indicate that Coulomb interactions between the latter defects and (at least partially) compensated, negatively charged, boron acceptors, generate the 3.5 and 4.6 eV bands, which may be considered as higher energy (≈ 0.6 eV) replicas of the 2.9 and 4 eV bands. In both cases, two electrons and a hole interact just before the hole combines with an electron. Such a configuration of charges seems related to, and could possibly be described as, a type of ”ionised exciton molecule”, where the ”bonding” of two negative ”nuclei” is facilitated by the presence of the hole. The CL measurements further indicate that the 2.4 eV band forms when a high enough density of, in this case, neutral acceptors are present. These neutral acceptors compete with the valence band to supply holes for recombination at the negatively charged, acceptor-type, intrinsic defects which are, in the absence of the boron, responsible for the generation of the blue, 2.9 eV band. Received: 5 December 1997 / Accepted: 13 December 1997     

Load forecasting using a multivariate meta-learning system

Although over a thousand scientific papers address the topic of load forecasting every year, only a few are dedicated to finding a general framework for load forecasting that improves the performance, without depending on the unique characteristics of a certain task such as geographical location. Meta-learning, a powerful approach for algorithm selection has so far been demonstrated only on univariate time-series forecasting. Multivariate time-series forecasting is known to have better performance in load forecasting. In this paper we propose a meta-learning system for multivariate time-series forecasting as a general framework for load forecasting model selection. We show that a meta-learning system built on 65 load forecasting tasks returns lower forecasting error than 10 well-known forecasting algorithms on 4 load forecasting tasks for a recurrent real-life simulation. We introduce new metafeatures of fickleness, traversity, granularity and highest ACF. The meta-learning framework is parallelized, component-based and easily extendable.     

Intramyocardial Inflammation after COVID-19 Vaccination: An Endomyocardial Biopsy-Proven Case Series

Myocarditis in response to COVID-19 vaccination has been reported since early 2021. In particular, young male individuals have been identified to exhibit an increased risk of myocardial inflammation following the administration of mRNA-based vaccines. Even though the first epidemiological analyses and numerous case reports investigated potential relationships, endomyocardial biopsy (EMB)-proven cases are limited. Here, we present a comprehensive histopathological analysis of EMBs from 15 patients with reduced ejection fraction (LVEF = 30 (14–39)%) and the clinical suspicion of myocarditis following vaccination with Comirnaty^® (Pfizer-BioNTech) (n = 11), Vaxzevria^® (AstraZenica) (n = 2) and Janssen^® (Johnson & Johnson) (n = 2). Immunohistochemical EMB analyses reveal myocardial inflammation in 14 of 15 patients, with the histopathological diagnosis of active myocarditis according the Dallas criteria (n = 2), severe giant cell myocarditis (n = 2) and inflammatory cardiomyopathy (n = 10). Importantly, infectious causes have been excluded in all patients. The SARS-CoV-2 spike protein has been detected sparsely on cardiomyocytes of nine patients, and differential analysis of inflammatory markers such as CD4⁺ and CD8⁺ T cells suggests that the inflammatory response triggered by the vaccine may be of autoimmunological origin. Although a definitive causal relationship between COVID-19 vaccination and the occurrence of myocardial inflammation cannot be demonstrated in this study, data suggest a temporal connection. The expression of SARS-CoV-2 spike protein within the heart and the dominance of CD4⁺ lymphocytic infiltrates indicate an autoimmunological response to the vaccination.     

Development of a Modelica Compiler Using JastAdd

This paper describes experiences from implementing key parts of a compiler for Modelica, an object-oriented language supporting declarative modeling and simulation of complex physical systems. Our implementation uses the attribute-grammar based tool JastAdd. In particular, we discuss the implementation of Modelica name analysis which is highly context-dependent, type analysis which is based on structural subtyping, and flattening which is a fundamental part of the Modelica compilation process.of so called modifications, Modelica.     

Enforcing structural regularities in software using IntensiVE

The design and implementation of a software system is often governed by a variety of coding conventions, design patterns, architectural guidelines, design rules, and other so-called structural regularities. To prevent a deterioration of the system’s source code, it is important that these regularities are verified and enforced upon evolution of the system. The Intensional Views Environment (IntensiVE), presented in this article, is a tool suite for specifying relevant structural regularities in an (object-oriented) software system and verifying them against the current and later versions of the system. At the heart of the IntensiVE tool suite are (logic) program queries and the model of intensional views and relations, through which regularities are expressed. Upon verification of these regularities in the source code of the system, IntensiVE reports the code entities (i.e. classes, methods, variables, statements, etc.) that violate these constraints. We present IntensiVE and illustrate its application to the verification of an Abstract Factory design pattern in the implementation of a software system.     

Long‐Range Domain Structure and Symmetry Engineering by Interfacial Oxygen Octahedral Coupling at Heterostructure Interface

In epitaxial thin film systems, the crystal structure and its symmetry deviate from the bulk counterpart due to various mechanisms such as epitaxial strain and interfacial structural coupling, which is accompanyed by a change in their properties. In perovskite materials, the crystal symmetry can be described by rotations of sixfold coordinated transition metal oxygen octahedra, which are found to be altered at interfaces. Here, it is unraveled how the local oxygen octahedral coupling at perovskite heterostructural interfaces strongly influences the domain structure and symmetry of the epitaxial films resulting in design rules to induce various structures in thin films using carefully selected combinations of substrate/buffer/film. Very interestingly it is discovered that these combinations lead to structure changes throughout the full thickness of the film. The results provide a deep insight into understanding the origin of induced structures in a perovskite heterostructure and an intelligent route to achieve unique functional properties.     

The effect of random grain distributions on fatigue crack initiation in a notched coarse grained superalloy specimen

Coarse grained superalloys are of large interest in high temperature applications, and can be found in e.g. gas turbine components, where great care must be given with respect to high temperature fatigue. Due to the large grain size, the material behaviour at e.g. sharp notches cannot be considered homogeneous. As a consequence, the fatigue behaviour is likely to expose a large variation. In order to numerically investigate this variation, a Monte Carlo analysis has been carried out by 100 FE-simulations of notched specimens, where placements and orientations of the grains were randomised. Furthermore, each grain was modelled as a unique single-crystal, displaying both anisotropic elastic and plastic behaviour and tension/compression asymmetry. The effect of randomness was investigated by the obtained dispersion in fatigue crack initiation life. It was concluded that the fatigue life behaviour of coarse grained nickel-base superalloys may show a considerable variation, which cannot be captured by one single deterministic analysis based on data for a homogenised material. Furthermore, the dispersion is of such a magnitude that it needs to be taken into account in industrial applications where highly stressed coarse grained materials are used.     

Natural Language and Logic of Agency

This light piece reflects on analogies between two often disjoint streams of research: the logical semantics and pragmatics of natural language and dynamic logics of general information-driven agency. The two areas show significant overlap in themes and tools, and yet, the focus seems subtly different in each, defying a simple comparison. We discuss some unusual questions that emerge when the two are put side by side, without any pretense at covering the whole literature or at reaching definitive conclusions.     

Escape trajectories are deflected when fish larvae intercept their own C-start wake

Fish larvae may intercept their own wake during sharp turns, which might affect their escape performance. We analysed C-starts of larval zebrafish (Danio rerio, Hamilton, 1822) using a computational fluid dynamics approach that simulates free swimming (swimming trajectory is determined by fluid forces) by coupling hydrodynamics and body dynamics. The simulations show that fish may intercept their own wake when they turn by 100–180°. During stage 1 of a C-start, the fish generates a strong jet at the tail that is shed into the wake. During stage 2, the fish intercepts this wake. Counterfactual simulations showed that wake interception increased the lateral force on the fish and reduced the fish''s turning angle by more than 5°. Wake interception caused no significant acceleration tangential to the trajectory of the fish and did not affect total power output. While experimental and simulation evidence suggests that fish larvae can either undershoot or intercept but not overshoot their wake, our simulations show that larger fish might be able to avoid intercepting their wake by either under- or overshooting. As intercepting its own wake modifies the fish''s escape trajectory, fish should account for this effect when planning their escape route.