Co-design in the Exascale Computing Project

We provide an overview of the six co-design centers within the U.S. Department of Energy’s Exascale Computing Project, each of which is described in more detail in a separate paper in this special issue. We also give a perspective on the evolution of computational co-design.

On the rim tori refinement of relative Gromov–Witten invariants

We construct Ionel–Parker’s proposed refinement of the standard relative Gromov–Witten invariants in terms of abelian covers of the symplectic divisor and discuss in what sense it gives rise to invariants. We use it to obtain some vanishing results for the standard relative Gromov–Witten invariants. In a separate paper, we describe to what extent this refinement sharpens the usual symplectic sum formula and give further qualitative applications.

Preliminary report on Trichoptera from the headwaters of the Cuanavale, Cuito, Cuembo and Cuando Rivers in Angola

Trichoptera larvae and adults were collected as part of an overall assessment of aquatic macroinvertebrate diversity in the major headwater tributaries of the Okavango and Zambezi River basins in Angola. This report documents one of the National-Geographic-funded, Okavango-Wilderness-Project expeditions undertaken between October and November 2016. A total of 21 sites on the Cuanavale, Cuito, Cuando, and Cuembo Rivers and some of their tributaries were sampled. Biotopes sampled in source lakes, headwater streams, pools, and large rivers included mostly sandy substrates, aquatic emergent and submerged vegetation, marginal vegetation and (rarely) bedrock, stones, or gravel. Light trap collecting was possible at only seven sites. With both adults and larvae collected, at least 55 species in seven families (Philopotamidae, Dipseudopsidae, Ecnomidae, Hydropsychidae, Hydroptilidae, Leptoceridae, and Sericostomatidae) were recorded. The Leptoceridae were the most abundant family, represented by ten genera and 22 species. There are a number of unnamed species which will be described in a separate paper.

Takagi–Taupin dynamical X-ray diffraction simulations of asymmetric X-ray diffraction from crystals: the effects of surface undulations

Dynamical X-ray diffraction simulations from crystals with surface undulations are reported. The Takagi–Taupin equations are applied and used to derive results in good agreement with experimental data reported in a separate paper [Macrander, Pereira, Huang, Kasman, Qian, Wojcik & Assoufid (2020). J. Appl. Cryst. 53, 789–792]. The development of Uragami [J. Phys. Soc. Jpn, (1969), 27, 147–154] is followed. Although previous work by Olekhnovich & Olekhnovich [Acta. Cryst. (1980), A36, 22–27] treated a crystal in the shape of a round cylinder, there do not seem to be any reports of previous dynamical X-ray diffraction treatments specifically for surface undulations. The significance of the present work is that it bridges the diffraction treatment of more classical dynamical diffraction theory, which assumes a flat surface, and the simple kinematic diffraction theory. The kinematic theory has, to date, been the primary means of simulating X-ray diffraction from surfaces.

Numerical Analysis of the Combustion of Gases Generated during Biomass Carbonization

The paper deals with the analysis of the combustion of volatiles evolved during thermolysis (thermal treatment) of biomass feedstock. The process is tailored to produce charcoal (biochar), heat and electricity and the whole system consists of a carbonizer, afterburning chamber and steam recovery boiler. In order to maintain safe operation of the carbonizer the process temperature has to be maintained at an acceptable level and thus the majority of gases evolved during biomass processing have to be combusted outside in the afterburning chamber. In this paper the combustion of those gases in a specially-designed combustion chamber was investigated numerically. The calculation results indicated that the production of the biochar has to be carried out with tight integration and management of the heat produced from the combustion of the volatiles and the emission of CO and methane may be maintained at a low level by optimization of the combustion process. The most promising effects were achieved in cases C4 and C5 where the gas was fed tangentially into the afterburning chamber. The calculation results were then used for the design and manufacture of a pilot reactor—from which the parameters and operational data will be presented and discussed in a separate paper.

New species and records of Ptiliidae (Coleoptera) from Africa in the Collection of the Natural History Museum, London

Ptiliidae collected in Africa (Ivory Coast, Mozambique, São Tomé, Sierra Leone) 2015–2017 under the auspices of the African Natural History Research Trust and the Natural History Museum, London, are determined to 24 species, 9 of which are new to science: Actidium loma sp. n., Actidium milesi sp. n., Actidium takanoi sp. n., Actidium acutum sp. n., Erro goffi sp. n., Ptilium maputense sp. n., Cissidium aristophanousi Darby (in a separate paper in press), Ptinella clio sp. n., and Ptinella euterpe sp. n.. New records are provided for Ptenidium nitidum Heer, Bambara frosti Dybas, Bambara magnifica Darby, Bambara joannis Vuillet, Ptiliola semitaria Darby, Nephanes marchali (Vuillet), Nephanes plurijugosus Darby, Nephanes titan (Newman), Acrotrichis africana Johnson, Acrotrichis africanoides Johnson, Acrotrichis capensis Johnson, Acrotrichis cephalotes Allibert, Acrotrichis discoloroides Johnson, Acrotrichis setigera Johnson and Acrotrichis tersa Johnson. A table is included listing all known species of Acrotrichis from Africa and the countries where they were found.

Mathematical problems associated with errors in estimating distances to galaxies

I generate many mock samples for applying the Monte Carlo method in order to estimate the bias of the Hubble constant because of the use of estimates of distances to galaxies determined from statistical dependences. I add errors to the original sample generated according to the Hubble law. In doing so, I use two possible options for generating errors in distance, having a constant relative error. Both are practical, but there are some math problems with them. I discuss their effect on the properties of the mock sample. The application of the standard least squares method is discussed and shown that it leads to an underestimation of the slope in the Hubble law. A formula is derived for calculating this slope using the maximum likelihood method and it is shown that it is applicable only for one of the variants of the sample noising. All estimates were obtained theoretically, without using the results of mock samples processing, which are described in a separate paper.

A központosított felhasználó azonosítás jelene és jövője: biztonságos infrastruktúra vagy időzített bomba?

Kutatási projektünk célkitűzése a globálisan központosított felhasználó azonosítás bevezetés lehetőségének vizsgálata, támogatási modellek kidolgozása. Hipotézisünk, hogy a globálisan központosított felhasználó azonosítás eredményesen növelheti a biztonságot és hozzájárulhat az adatvédelmi előírások hatékony, gyakorlati implementálásához. Az olvasót, jelen publikációnk keretében, egy úton szeretnénk végigvezetni, melynek célállomása hipotézisünk igazolása, miközben átfogóan megismerheti a közelmúlt adatvédelmi incidenseinek hatásait, iránymutatást kaphat mind felhasználóként, mind szolgáltatóként a biztonság növelésére a személyes adatok megosztásával kapcsolatosan és nem elhanyagolandó, kutatásunk célkitűzéseit. --- The present and future of centralized user authentication: secure infrastructure or a time-bomb? The goal of our research project is to exam the possibility of using globally centra¬lized user authentication and developing support models. Our hypothesis is that glob¬ally centralized user identification can effectively increase security and contribute to the effective implementation of data protection regulations in practice. In the con¬text of our present publication, the reader would like to be guided along a path, the purpose of which is to prove our hypothesis while gaining a comprehensive under¬standing of the effects of recent data protection incidents, providing guidance both as a user and as a service provider to enhance security in sharing personal information and not neglecting the goals of our research. We will publish more detailed theoretical and implementation descriptions of our models in a separate paper.

Development of the polish harbours information and control system

The paper presents reasons for establishing of the Polish Harbours Information and Control System (PHICS) and the analysis of its four constituent components: IMO - FAL, HAZMAT, PAS - REG and PSC. The fifth component – databases of the seafarers, training centres and Polish Central Maritime Examination Commission are analysed in a separate paper presented on the same conference.

International schools: leadership reviewed

This article provides a systematic review of research on leadership in international schools, though not focusing on International Baccalaureate schools which are the focus of a separate paper. International schools are autonomous, private bodies that cater to the globally advantaged. Accordingly, this literature review views them and their leadership through the Bourdieusian concept of distinction. Educational leaders in this context face considerable complexities. International schools thrive on the distinction they confer, it being intrinsic to these schools’ identity. International schools can be understood as existing on a matrix, or spectrum, between conceptions of international and global; equitable and market-place. The review finds that international schools experience considerable unhelpful change and transition, where consistency is highly prized yet difficult to achieve. Along with tensions between their equitable and market orientation, transition emerges as the most significant challenge facing educational leaders in this context.