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On Greenbergs’ classification of African languages
No full textGreenberg's classification of the languages of Africa --- typically understood as his 1963 division into 4 families --- has been enormously influential. Although earlier work has pointed out various shortcomings, in the present paper we systematically examine the completeness, accuracy (against the current state-of-the-art) and evidential basis of the Greenberg 1963 classification. This comparison shows that the quality of this classification has much in common with the commonly rejected classifications by Greenberg of languages in the rest of the world. Moreover, it could not possibly have been produced by a strict application of the alleged method of 'mass comparison'. A better explanation for the classification outcome is rather a procedure wherein a researcher is lead to interpret chance resemblances as evidence of genealogical relationship. It is difficult to pinpoint why Greenberg's classification of African languages became so influential, but we nevertheless provide a few key pointers
Understanding ecohydrology and biodiversity in aquatic nature-based solutions in urban streams and ponds through an integrative multi-tracer approach
No full textRapid urbanization and climate change affect ecohydrology, biodiversity, and water quality in urban freshwaters. Aquatic nature-based solutions (aquaNBSs) are being widely implemented to address some of the ecological and hydrological challenges that threaten urban biodiversity and water security. However, there is still a lack of process-based evidence of ecohydrological interactions in urban aquaNBSs and their relationship to water quality and quantity issues at the ecosystem level. Through a novel, integrative multi-tracer approach using stable water isotopes, hydrochemistry, and environmental DNA we sought to disentangle the effects of urbanization and hydroclimate on ecohydrological dynamics in urban aquaNBSs and understand ecohydrological functioning and the future resilience of urban freshwaters. Stable isotopes and microbial data reflected a strong influence of urban water sources (i.e., treated effluent, urban surface runoff) across stream NBSs. The results show potential limitations of aquaNBS impacts on water quality and biodiversity in effluent-impacted streams, as microbial signatures are biased towards potentially pathogenic bacteria. Urban ponds appear to be more sensitive to hydroclimate perturbations, resulting in increased microbial turnover and lower microbial diversity than expected. Furthermore, assessment of macrophytes revealed low diversity and richness of aquatic plants in both urban streams and ponds, further challenging the effectiveness of NBSs in contributing to aquatic diversity. This also demonstrates the need to adequately consider aquatic organisms in planned restoration projects, particularly those implemented in urban ecosystems, in terms of habitat requirements. Our findings emphasize the utility of integrated tracer approaches to explore the interface between ecology and hydrology and provide insights into the ecohydrologic functioning of aquaNBSs and their potential limitations. We illustrate the benefit of coupling ecological and hydrological perspectives to support future NBS design and applications that consider the interactions between water and the ecosystem more effectively.Bundesministerium für Bildung und ForschungEinstein Stiftung BerlinDeutsche ForschungsgemeinschaftNarodowe Centrum NaukiPeer Reviewe
Social Order in Science through the Prism of Large Research Collaborations
No full textLarge research collaborations are a strategically relevant object of study for understanding the social order of science. We argue that studying large research collaborations allows to address three interrelated questions that are crucial for the sociology of science; namely, how the social order of science is shaped, how science is embedded in society, and how science relates to politics. Against this background, we empirically investigate how power-knowledge relations are set up in the self-government of large research collaborations and how these self-governing forms of organization are justified or legitimized. Based on a literature review, we present and analyse two empirical cases, the European Southern Observatory (ESO) and the next generation Event Horizon Telescope (ngEHT) and identify common issues that are continuously controversial: membership, distribution of power/participation, legitimization, and recognition/scientific rewards. Arguing that these characteristics mirror and constitute crucial elements of social order in science, we elaborate on their normative implications and find constitutive elements of social order in self-governing political collectives, among them a preference for decentralized and dynamic forms of governance
Structure Factor Retrieval from Large-Angle Rocking-Beam Electron Diffraction
No full textEine wohlbekannte Herausforderung in der Kristallographie ist das sogenannte Phasenproblem. Jüngste Fortschritte in der Large-Angle Rocking-Beam Electron Diffraction (LARBED) ermöglichen es, bislang ignorierte Informationen aus der dynamischen Streuung, zur Lösung des Phasenproblems zu nutzen. Die Bestimmung komplexer Strukturfaktoren aus dynamischer Streuung stellt bislang jedoch eine weiteres ungelöstes Problem dar. Derzeitige Ansätze sind zumeist auf dünne Proben mit einfachen atomaren Strukturen beschränkt. In dieser Arbeit werden robuste Anpassungsansätze zur Strukturfaktorermittelung für LARBED-Experimente entwickelt, welche diese Beschränkungen überwinden. Zudem wird ein elektronenoptischer Strahlengang zur vollautomatisierten Realisierung solcher Experimente in einem hochmodernen Elektronenmikroskop implementiert. Die resultierenden simulierten und experimentellen Ergebnisse zeigen, dass die Strukturfaktoren und damit das projizierte elektrostatische 2D-Potenzial verschiedener Kristallstrukturen mit einer Auflösung im Sub-Angström-Bereich rekonstruiert werden können. Vorläufige Ergebnisse zur Rekonstruktion des dreidimensionalen elektrostatischen Potenzials demonstrieren zudem die Praktikabilität des vorgestellten Ansatzes.The phase problem has long vexed crystallographers. Recent advances in large-angle rocking-beam electron diffraction (LARBED) allow crystallographers to harness heretofore ignored dynamical scattering data toward solving it. However, retrieving complex structure factors from dynamical scattering is an open problem: previous approaches using LARBED were limited to thin samples with simple atomic structures. This work presents robust fitting approaches to structure factor retrieval for LARBED experiments which overcome these limitations. In addition, an electron-optical beam path for the fully automated realization of such experiments is implemented in a state-of-the-art electron microscope. Simulated and experimental results are shown to recover the structure factors and thus the 2D projected electrostatic potential of several crystals with sub-angstrom resolution, and preliminary results are shown for reconstructing the 3D electrostatic potential, demonstrating the feasibility of the presented approach
On the degree of irrationality of low genus K3 surfaces
No full textGiven a general polarized K3 surface S⊂Pg of genus g≤14, we study projections of minimal degree and their variational structure. In particular, we prove that the degree of irrationality of all such surfaces is at most 4, and that for g=7,8,9,11 there are no rational maps of degree 3 induced by the primitive linear system. Our methods combine vector bundle techniques à la Lazarsfeld with derived category tools and also make use of the rich theory of singular curves on K3 surfaces.Peer Reviewe
Fachspezifische Studien- und Prüfungsordnung für den weiterbildenden Masterstudiengang Humboldt Master of Laws
No full textStrategies for Embedding Research Data Management Through Effective Communication
No full textThe article processing charge was funded by the Open Access Publication Fund of Humboldt-Universität zu Berlin.Effective research data management (RDM) is essential for ensuring research integrity, reproducibility, and compliance with FAIR principles. Despite the development of comprehensive RDM frameworks, many institutions still struggle to ensure widespread engagement and compliance among researchers and staff. Adoption of RDM practices remains slow due to limited awareness, unclear benefits, and perceived administrative burdens. Using Mendelow’s Matrix, this study draws on survey data to map key stakeholders, such as researchers, RDM professionals, institutional leadership, funding bodies, and infrastructure providers, based on their power and interest to ensure developing tailored communication strategies. This paper presents a communication strategy to enhance RDM adoption by improving visibility, fostering engagement, and encouraging the integration of RDM into research workflows and curricula. It outlines key approaches, including awareness campaigns, targeted publishing, strategic partnerships, and knowledge-driven promotion to embed RDM into research workflows.The article processing charge was funded by the Open Access Publication Fund of Humboldt-Universität zu Berlin.Open Access Publication Fund of Humboldt-Universität zu BerlinPeer Reviewe
An Oxoiron(IV) Complex Supported by an N‐Alkylated Cyclam Ligand System Containing a Pendant Alcohol Moiety
No full textThe effect of a pendant neutral alcohol moiety in the N‐alkylated cyclam (1,4,8,11‐tetraazacyclotetradecane) ligand backbone is examined for the non‐heme mononuclear oxoiron(IV) unit in [FeIV(Osyn)(TMC‐HOR)(NCCH3)]2+ (1‐syn) (TMC‐HOR=2‐(4,8,11‐trimethyl‐1,4,8,11‐tetraazacyclotetradecan1‐yl)ethan‐1‐ol). Unlike in the related [FeIV(Oanti)(TMC‐SR)]+ (3‐anti) (TMC‐SR=1‐mercaptoethyl‐4,8,11‐trimethyl‐1,4,8,11‐tetraazacyclotetradecane) complex, bearing an axial mono‐anionic thiolate ligand trans to the oxo unit, the alcohol moiety in 1‐syn stays protonated and does not axially coordinate to iron. The protonation of the alcohol moiety is a prerequisite for the stabilization of the oxoiron(IV) core; it presumably serves as a hydrogen bonding donor to the oxoiron(IV) unit, which is positioned syn to the three methyl groups. Comparative reactivity studies reveal 1‐syn to be a stronger hydrogen atom abstraction but weaker oxygen atom transfer agent relative to the [FeIV(Osyn)(TMC)(NCCH3)]2+ (2‐syn) complex, bearing the N‐tetramethylated cyclam (TMC) ligand.Peer Reviewe
Optimization of cold atom experiments: Development of a machine learning-enhanced cold atom platform for quantum sensor applications
No full textUltra-kalte Atome bieten vielseitige Möglichkeiten in verschiedenen Anwendungsbereichen. Es gibt Anwendungen im Bereich der Grundlagenphysik, wie Tests des schwachen Äquivalenzprinzips. Darüber hinaus sind Anwendungen außerhalb des Labors in Bereichen der Geodäsie, Sensorik und Quantenkommunikation möglich. Die Einführung von miniaturisierten und robusten Aufbauten ermöglicht es, Experimente auf Plattformen außerhalb eines Labors zu betreiben. Das Ziel dieser Arbeit ist die Konstruktion eines Bodentestsystems für Subsysteme, die für mobile Rubidium basierte Experimente entwickelt werden. Diese Arbeit stellt das Design des Systems vor, einschließlich eines kommerziellen Vakuumsystems, des optischen Aufbaus zur Erzeugung und Präparation des Lichts, der Steuerelektronik und das entwickelte Software-Ökosystem. Ein kompakter, robuster und miniaturisierter gekreuzter Dipolfallenaufbau wird implementiert. Dieser Aufbau wird charakterisiert, mit dem Ziel, optisch Bose-Einstein-Kondensate auf Mikrogravitationsplattformen zu erzeugen. Zum automatisierten des Betriebs von Quantensensoren werden 9 verschiedene Optimierer unter Nutzung des Experimentes verglichen. Es werden die Ergebnisse der Optimierung der Atomzahl an einem 10- und 18-dimensionalen mit unterschiedlichen Rauschpegeln vorgestellt. Die Tests zeigen die Vorteile der computergestützten Optimierung im Vergleich zu manuellen Herangehensweisen auf. Für das Projekt INTENTAS wird ein Lasersystem für den Einstein Fahrstuhl, eine neue μg-Anlage, entwickelt, gebaut und charakterisiert. Das Lasersystem wird das Fangen und Kühlen von 87Rb-Atomen ermöglichen. Es verwendet mikrointegrierte Diodenlaser und ein Schalt- und Verteilersystem, das eine Kombination aus Faser- und Freistrahloptiken verwendet. Das Lasersystem im im Einstein-Aufzug getestet und zeigt eine hohe Stabilität der optischen Leistungen in allen Pfaden.Ultra-cold atoms are a versatile tool for different applications. On the one hand, there are experiments in the field of fundamental physics such as testing the weak equivalence principle. Beyond the laboratory, applications include geodesy, sensing and quantum communication. The advent of miniaturized and robust setups led to experiments on microgravity platforms. The goal of this thesis is to construct a ground test bed for subsystems built for mobile experiments using rubidium. This thesis presents the design of this test bed, including a commercial vacuum system, the optical setup for the generation and preparation of the light, electronics and the developed software ecosystem. A robust and compact miniaturized crossed-beam optical dipole trap setup is implemented. It is characterized with the goal of producing all-optical Bose-Einstein condensates on microgravity platforms. The generation of cold atom clouds is a complex process which involves the optimization of noisy data in high dimensional parameter spaces. Therefore, 9 different optimizers were benchmarked using the experiment. This thesis presents the results of optimizing the atom number at a 10 and 18-dimensional problem and at different noise levels. The tests showed successfully the advantages of computer-aided optimization compared to manual processes. Within the project INTENTAS a laser system for the Einstein-Elevator, a new μg-facility, is built. As part of this thesis, the laser system for this experiment is developed, characterized and tested. The laser system will enable the trapping and cooling of 87Rb atoms. It uses micro-integrated diode lasers and a switching and distribution system utilizing a combination of fiber and free-space optics. The laser system was successfully tested in the Einstein-Elevator, demonstrating high stability of the optical powers in all paths