Rotating binary Bose-Einstein condensates and vortex clusters in quantum droplets

Quantum droplets may form out of a gaseous Bose-Einstein condensate, stabilized by quantum fluctuations beyond mean field. We show that multiple singly-quantized vortices may form in these droplets at moderate angular momenta in two dimensions. Droplets carrying these precursors of an Abrikosov lattice remain self-bound for certain timescales after switching off an initial harmonic confinement. Furthermore, we examine how these vortex-carrying droplets can be formed in a more pertubation-resistant setting, by starting from a rotating binary Bose-Einstein condensate and inducing a metastable persistent current via a non-monotonic trapping potential.Comment: 5 page, 4 figure

Perspectives on Digital Sustainability

This habilitation thesis presents perspectives on digital sustainability, a novel concept connecting digitalization with sustainability. It explains why digital artifacts such as software or data have to meet technical characteristics of quality, transparency, semantics and multiple locations in order to serve society in the long term. However, these requirements are just necessary but not sufficient preconditions to consider digital artifacts sustainable. Their associated ecosystem of businesses, governments, and individuals must also meet the legal and organizational characteristics of open license, shared tacit knowledge, participation, good governance, and diversified funding. And, finally, sustainable digital artifacts must lead to ecological, societal and economical benefits. This thesis statement is discussed in the introductory chapter of the habilitation. It connects and summarizes 13 refereed publications clustered in five perspectives on digital sustainability: In the first perspective, the path of defining the concept of digital sustainability is summarized. This part starts with a publication that introduced an initial set of characteristics for digital sustainability (Stuermer, 2014). The following article connects digital sustainability with digital preservation (Stuermer and Abu-Tayeh, 2016). These studies have eventually led to an extended publication in a sustainability journal elaborating the basic conditions of digital sustainability in detail (Stuermer et al., 2017a). The second perspective includes recent publications on open source software (OSS) research scrutinizing how patterns of digital sustainability are applied within the software development industry. One publication analyzes feature requests within the Eclipse OSS community (Heppler et al., 2016). The following article develops a maturity model of Inner Source, a special form of OSS development practices in an organization (Eckert et al., 2017). And one study in a computer science journal addresses different types of OSS governance by comparing independent and joint communities (Eckert et al., 2019). The next perspective focuses on the procurement of information technology (IT) which involves critical topics of knowledge management and governance related to digital sustainability. Analyzing data crawled from the Swiss public procurement platform Simap.ch exposes lock-in effects, outsourcing decisions as well as multisourcing within the software industry. One article in this perspective introduces the methodology and the dataset pointing out the high level of direct awards within the IT sector (Stuermer et al., 2017b). Another publication tests hypotheses on contract choice in regard to knowledge specificity and task scope (Krancher and Stuermer, 2018a). And one study explains multisourcing decisions using a large dataset on public procurement of IT in Switzerland (Krancher and Stuermer, 2018b). The subsequent perspective highlights open data and linked data as another form of sustainable digital artifacts. One publication proposes a framework permitting the measurement of the impact of open data (Stuermer and Dapp, 2016). Another article introduces linked open government data (LOGD), a kind of graph-structured open data stored in different kinds of platforms (Hitz-Gamper et al., 2019). The final perspective extends the phenomenon of open data into the area of governmental services. By linking the concepts of public governance and open government one article shows how transparency and participation are achieved with digital tools (Stuermer and Ritz, 2014). Another publication includes an empirical analysis of the FixMyStreet open government platform in Zurich called “Züri wie neu” using open data and a user survey to identify the motivation of citizens using this digital tool (Abu-Tayeh et al., 2018)

EXTINCTION OF THE OBLIGATION TO CONTRIBUTE TO TRADE UNIONS

ABSTRACTThe article deals with the issue of union contribution from its creation and compulsory until the advent of Law 13467/2017, when it is no longer mandatory. The matter (extinction of the obligation) was taken to the Federal Supreme Court, which ruled on the constitutionality of the amendment.KEYWORDS: Extinction of the Obligation of the Union Contribution; Freedom of Association; Labor Reform.RESUMO O artigo aborda o tema da contribuição sindical a partir da sua criação e compulsoriedade até o advento da Lei nº 13.467/2017, quando deixou de ser obrigatória. A matéria (extinção da obrigatoriedade) foi levada ao Supremo Tribunal Federal, que decidiu pela constitucionalidade da alteração.PALAVRAS-CHAVE: Extinção da Obrigatoriedade da Contribuição Sindical; Liberdade Sindical; Reforma Trabalhista

What Drives Mineral Commodity Markets in the Long Run?

This thesis analyzes the long-run development of mineral commodity markets both from a theoretical and an empirical perspective. The first chapter presents a model that replicates long-term trends in non-renewable resource markets, namely stable prices and exponentially increasing extraction, for which we present data from 1792 to 2010. We add an extractive sector to an endogenous growth model of expanding varieties and directed technological change. Extractive firms can draw down resource stocks through extraction, but also renew stocks through investment in new extraction technology. Our results suggest that technological change in extraction technologies offsets the increasing demand for non-renewable resources in industrializing countries like China in the long run. In the second chapter I provide long-term evidence on the dynamic effects of supply and demand shocks on mineral commodity prices. I explore a new annual data-set on prices and production of copper, lead, tin, zinc, and crude oil from 1840 to 2010. Long-term price fluctuations are mainly driven by persistent ''world output-driven demand shocks'' and ''other demand shocks''. Historical accounts of market events suggest that ''other demand shocks'' mainly capture changes in inventories. Due to oligopolistic industry structures, ''supply shocks'' exhibit some effects on the prices of tin and copper, but not on the prices of lead and zinc. Subsample results for crude oil indicate that during earlier periods ''supply shocks'' have been important drivers. My results suggest that prices will return to their stable or even declining trends in the long run. The third chapter deals with the long-term determinants of demand for mineral commodities. It is the first to provide empirical evidence covering the main periods of industrialization as far back as 1840. I extend the standard partial adjustment model to account for country-specific economic structures, technological change, and endogeneity. I find that the demand for aluminum and copper increases disproportionately high over the course of industrialization, while it decreases for lead, tin, and zinc. This suggests that the industrialization in China, for example, will cause aluminum and copper demand to rise to far higher levels than the demand for lead, tin, and zinc. The demand for all examined mineral commodities is highly inelastic with respect to price in the long run. According to theory, this causes incentives for conflict over these commodities and makes markets prone to speculation. All variables adjust slowly to equilibrium, which helps to explain the extended fluctuation in these markets