64,347 Works

Detecting and characterising an englacial conduit network within a temperate Swiss glacier using active seismic, ground penetrating radar and borehole analysis

Gregory Church, Andreas Bauder, Melchior Grab, Lasse Rabenstein, Satyan Singh & Hansruedi Maurer
Englacial hydrology plays an important role in routing surface water to the glacier's bed and it consequently affects the glacier's dynamics. However, it is often difficult to observe englacial conduit conditions on temperate glaciers because of their short-lived nature. We acquired repeated active surface seismic data over the Rhone Glacier, Switzerland to monitor and characterise englacial conduit conditions. Amplitude-versus-angle analysis suggested that the englacial conduit is water filled and between 0.5 and 4 m thick....

Synchronous transmissions on Bluetooth 5 and IEEE 802.15.4 – A replication study

Romain Jacob, Anna-Brit Schaper, Andreas Biri, Reto Da Forno & Lothar Thiele
Synchronous transmissions (ST) is a wireless communication technique that has been shown to be particularly efficient in low-power multi-hop networks. Since 2011, research on ST mainly focused on the physical layer defined by the IEEE 802.15.4 standard. Nowadays, Bluetooth is another pervasive technology embedded by default in almost all connected objects; researchers recently started to investigate whether the benefits of ST also apply to Bluetooth. This paper presents the results of a replication study of...

Microbial mutualism at a distance: The role of geometry in diffusive exchanges

François J. Peaudecerf, Freddy Bunbury, Vaibhav Bhardwaj, Martin A. Bees, Alison G. Smith, Raymond E. Goldstein & Ottavio A. Croze
The exchange of diffusive metabolites is known to control the spatial patterns formed by microbial populations, as revealed by recent studies in the laboratory. However, the matrices used, such as agarose pads, lack the structured geometry of many natural microbial habitats, including in the soil or on the surfaces of plants or animals. Here we address the important question of how such geometry may control diffusive exchanges and microbial interaction. We model mathematically mutualistic interactions...

A measure of majorization emerging from single-shot statistical mechanics

Dario Egloff, Oscar C.O. Dahlsten, Renato Renner & Vlatko Vedral
The use of the von Neumann entropy in formulating the laws of thermodynamics has recently been challenged. It is associated with the average work whereas the work guaranteed to be extracted in any single run of an experiment is the more interesting quantity in general. We show that an expression that quantifies majorization determines the optimal guaranteed work. We argue it should therefore be the central quantity of statistical mechanics, rather than the von Neumann...

The dynamics of overlayer formation on catalyst nanoparticles and strong metal-support interaction

Arik Beck, Xing Huang, Luca Artiglia, Maxim Zabilskiy, Xing Wang, Przemyslaw Rzepka, Dennis Palagin, Marc Willinger & Jeroen A. Van Bokhoven
Nature Communications, 11 (1)

Model independent analysis of supernova data, dark energy, trans-Planckian censorship and the swampland

Lavinia Heisenberg, Matthias Bartelmann, Robert Brandenberger & Alexandre Refregier
In this Letter, we consider the model-independent reconstruction of the expansion and growth functions from the Pantheon supernova data. The method relies on developing the expansion function in terms of shifted Chebyshev polynomials and determining the coefficients of the polynomials by a maximum-likelihood fit to the data. Having obtained the expansion function in a model-independent way, we can then also determine the growth function without assuming a particular model. We then compare the results with...

Kin discrimination in social yeast is mediated by cell surface receptors of the Flo11 adhesin family

Stefan Brückner, Rajib Schubert, Timo Kraushaar, Raimo Hartmann, Daniel Hoffmann, Eric Jelli, Knut Drescher, Daniel J Müller, Lars-Oliver Essen & Hans-Ulrich Mösch
Microorganisms have evolved specific cell surface molecules that enable discrimination between cells from the same and from a different kind. Here, we investigate the role of Flo11-type cell surface adhesins from social yeasts in kin discrimination. We measure the adhesion forces mediated by Flo11A-type domains using single-cell force spectroscopy, quantify Flo11A-based cell aggregation in populations and determine the Flo11A-dependent segregation of competing yeast strains in biofilms. We find that Flo11A domains from diverse yeast species...

Biases in the albedo sensitivity to deforestation in CMIP5 models and their impacts on the associated historical radiative forcing

Quentin Lejeune, Edouard Léopold Davin, Grégory Duveiller, Bas Crezee, Ronny Meier, Alessandro Cescatti & Sonia I. Seneviratne
Climate model biases in the representation of albedo variations between land cover classes contribute to uncertainties on the climate impact of land cover changes since pre-industrial times, especially on the associated radiative forcing. Recent publications of new observation-based datasets offer opportunities to investigate these biases and their impact on historical surface albedo changes in simulations from the fifth phase of the Coupled Model Intercomparison Project (CMIP5). Conducting such an assessment is, however, complicated by the...

Gibbs-preserving maps outperform thermal operations in the quantum regime

Philippe Faist, Jonathan Oppenheim & Renato Renner
In this brief paper, we compare two frameworks for characterizing possible operations in quantum thermodynamics. One framework considers thermal operations—unitaries which conserve energy. The other framework considers all maps which preserve the Gibbs state at a given temperature. Thermal operations preserve the Gibbs state; hence a natural question which arises is whether the two frameworks are equivalent. Classically, this is true—Gibbs-preserving maps are no more powerful than thermal operations. Here, we show that this no...

Operational approach to time and clocks in quantum theory

Sandra Stupar
Throughout the existence of humankind, people have organised their lives based on the sunrise and sunset, the Moon phases and star movements. Nature has guided our daily routines, as it still does, and it would be hard to imagine what life would look like without the already known cycles imposed by nature. As the humanity progressed, we have realised that a day is not always of the same length, but our sleep cycle most often...

Examining pelagic carbonate-rich sediments as an archive for authigenic uranium and molybdenum isotopes using reductive cleaning and leaching experiments

Matthew O. Clarkson, Kim Müsing, Morten B. Andersen & Derek Vance
Novel metal isotope systematics are increasingly used to understand environmental change in geological history. On a global scale, the isotopic budgets of these metals respond to a range of environmental processes, allowing them to trace complex changes in the global climate system and carbon cycle. In particular, uranium (U) and molybdenum (Mo) isotopes are useful tools for quantifying the global extent of oceanic anoxia and euxinia respectively. The oceanic signature of these metals is recorded...

{110} Slip with {112} slip traces in bcc Tungsten

Cecile Marichal, Helena Van Swygenhoven, Steven Van Petegem & Camelia Borca
While propagation of dislocations in body centered cubic metals at low temperature is understood in terms of elementary steps on {110} planes, slip traces correspond often with other crystallographic or non-crystallographic planes. In the past, characterization of slip was limited to post-mortem electron microscopy and slip trace analysis on the sample surface. Here with in-situ Laue diffraction experiments during micro-compression we demonstrate that when two {110} planes containing the same slip direction experience the same...

Tangible Phenomenological Thermodynamics

Philipp Kammerlander
In this thesis, the foundations of classical phenomenological thermodynamics are being thoroughly revisited. A new rigorous basis for thermodynamics is laid out in the main text and presented in full detail in the appendix. All relevant concepts, such as work, heat, internal energy, heat reservoirs, reversibility, absolute temperature and entropy, are introduced on an abstract level in a way that their intuitive meaning is reflected in the mathematical structure and connected through traditional results, such...

S. Ehrmanntraut: Wie Computer heimisch wurden: Rezension

Markus Schmid

Glacier thickness estimations of alpine glaciers using data and modeling constraints

Lisbeth Langhammer, Melchior Grab, Andreas Bauder & Hansruedi Maurer
Advanced knowledge of the ice thickness distribution within glaciers is of fundamental importance for several purposes, such as water resource management and the study of the impact of climate change. Ice thicknesses can be modeled using ice surface features, but the resulting models can be prone to considerable uncertainties. Alternatively, it is possible to measure ice thicknesses, for example, with ground-penetrating radar (GPR). Such measurements are typically restricted to a few profiles, with which it...

A Non-Probabilistic Framework for Scientific Theories

Daniela Frauchiger

Evolution from magmatic to hydrothermal activity beneath the Cerro Escorial volcano (NW Argentina) as sampled by erupted quartz and brines

Alina M. Fiedrich, Christoph A. Heinrich & Olivier Bachmann
Large quartz pebbles erupted with the Escorial ignimbrite provide insight into the late-magmatic evolution of the shallow, cooling magmatic-hydrothermal system below the Cerro Escorial volcano of the Southern Central Volcanic Zone in the Argentine Andes. The ignimbrite is of relatively small volume, crystal-rich, dacitic in composition, and not particularly water-rich, as amphibole is absent. Eruption temperature was estimated to be close to 850 °C. The quartz pebbles provide insight into the magmatic-hydrothermal transition beneath the...

Natural Selection on Female Life-History Traits in Relation to Socio-Economic Class in Pre-Industrial Human Populations

Jenni E. Pettay, Samuli Helle, Jukka Jokela & Virpi Lummaa
Life-history theory predicts that resource scarcity constrains individual optimal reproductive strategies and shapes the evolution of life-history traits. In species where the inherited structure of social class may lead to consistent resource differences among family lines, between-class variation in resource availability should select for divergence in optimal reproductive strategies. Evaluating this prediction requires information on the phenotypic selection and quantitative genetics of life-history trait variation in relation to individual lifetime access to resources. Here, we...

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