WueData (Univ Würzburg)
Not a member yet
185 research outputs found
Sort by
Finite temperature fermion Monte Carlo simulations of frustrated spin-Peierls systems
No full textThe Abrikosov fermion representation of the spin-1/2 degree of freedom allows for auxiliary-field quantum Monte Carlo simulations of frustrated spin systems. This approach provides a manifold of equivalent actions over which the negative sign problem can be optimised. As a result, we can reach temperature scales well below the magnetic scale. Here, we show how to generalise this algorithm to spin-Peierls systems. In contrast to exact diagonalisation approaches, Monte Carlo methods are not Hilbert space bound such that the computational effort per sweep remains invariant when adding phonons. However, the computational effort required to generate Independent configurations increases in the presence of phonons. We also show that, for the specific case of the Kitaev-Heisenberg model, the inclusion of phonons does not render the negative sign problem more severe. This new algorithm hence allows us to investigate the interplay between phonon degrees of freedom and magnetic frustration. We present results for frustrated and non-frustrated spin systems.We thank M. Weber for providing the benchmark data of Fig. 1. We would like to thank W. Brenig, J. Knolle, R. Valenti and J. Willsher for useful discussions. We equally thank E. Huffman and J. Hofmann for discussion on how to generalise the ALF-code to include the spin-Peierls coupling. We gratefully acknowledge the Gauss Centre for Supercomputing e.V. for funding this project by providing computing time on the GCS Supercomputer SUPERMUC-NG at Leibniz Supercomputing, (project number pn73xu) as well as the scientific support and HPC resources provided by the Erlangen National High Performance Computing Center (NHR@FAU) of the Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU) under the NHR project b133ae. NHR Funding is provided by federal and Bavarian state authorities. NHR@FAU hardware is partially funded by the German Research Foundation (DFG) – 440719683. J.I thanks the DFG for financial support under the AS 120/19-1 grant (Project number, 530989922). T.S thanks the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter ct.qmat (EXC 2147, project-id 390858490). F.F.A. acknowledge financial support from the DFG under the grant AS 120/16-1 (Project number 493886309) that is part of the collaborative research project SFB Q-M&S funded by the Austrian Science Fund (FWF) F 86.Data set for the paper "Finite temperature fermion Monte Carlo simulations of frustrated spin-Peierls systems" available on https://arxiv.org/abs/2502.06565. The dataset contains results from auxiliary field quantum Monte Carlo for the systems studied in the mentioned paper
The influence of land distribution, areal extent and albedo on Mesoarchaean climate - global tas temperatures
No full textClimate change in the Mesoarchaean potentially played a pivotal role in facilitating gold mobilisation and deposition, ultimately contributing to the formation of the Witwatersrand gold province in the Kaapvaal Craton (South Africa) – the world’s largest known gold province. Almost all of the gold there occurs in the 2.90 – 2.79 Ga Central Rand Group, whereas the underlying 2.95 - 2.91 Ga West Rand Group, despite similar sedimentology, is essentially barren. This has been explained by differing degrees of chemical weathering, with intense weathering in Central Rand Group times having facilitated gold leaching from the Archaean hinterland. However, the drivers of this climatic change remain unsolved. To investigate this, we performed 140 simulations using the Planet Simulator, an Earth system model of intermediate complexity. We systematically assessed the effects of varying land distributions (diagonal, central, polar), land surface fractions (8–28 %), atmospheric CO₂-equivalent concentrations (3–30 %), and surface albedo (0.15–0.30). In addition to the expected strong dependence of global mean temperature on atmospheric greenhouse gas concentration, our results show reduced seasonality at higher atm. CO₂-equivalents. Increasing land area generally leads to cooling, except at low CO2-equivalent concentrations (3-5 %) and low albedo (<0.2). When land exceeds ~13 % of total Earth’s surface, it starts to have a pronounced effect on global climate. Among the spatial configurations, diagonal land distribution shows the highest climate sensitivity. The climatic shift around 2.9 Ga may be linked to emergence of extensive low-albedo (<0.2) surfaces (e.g., mafic/ultramafic rocks) and/or to the latitudinal drift of the Kaapvaal Craton into a more radiatively sensitive zone.
This dataset contains global 2-meter above the ground temperature (tas) at a horizontal resolution of T21 (64 x 32 grid points). The data are separated into two experimental configurations: (1) the effects of global land distribution and (2) the global effects of surface albedo.
Experiment 1: Effects of Global Land Distribution
This experiment investigated the influence of Mesoarchaean land distribution and pattern on global climate, focusing on the global mean near-surface air temperature (tas). Three idealised continental configurations were implemented, representing diagonal, central and polar land distribution. For each configuration the total land fraction relative to the planetary surface area was systematically varied in four steps: 8%, 13%, 20% and 28%.
Experiment 2: Global Effects of Albedo
In this experiment, only the diagonal land distribution with different fractions was used, while the surface albedo was systematically varied to assess its climatic impact. The prescribed albedo values were 0.15, 0.20, 0.25 and 0.30.
All simulations were performed using the Planet Simulator (PlaSim; Freadrich et al. 2005), an intermediate-complexity general circulation model. Postprocessing was conducted using PlaSim’s integrated postprocessor. The resulting data are provided in NetCDF format, representing 50-year simulations with the variable tas defined on the dimensions [long(64), lat(32), time (18263)]
Freezing the Moment: Monitoring Freezing Processes under MAS Conditions
No full textNMR spectroscopy under magic angle spinning (MAS) conditions can be employed to study the freezing of aqueous solutions and gel-like systems without the need for specialized equipment. This is attractive as one sample can be studied in its liquid and its solid form without changing the experimental setup. There are multiple areas which benefit from such an analysis. Here, we will thoroughly study the freezing process of various aqueous systems containing multiple NMR active nuclei (1H, 11B, 13C, 23Na, 79Br) to gain detailed insights into what are prerequisites, what problems one must be aware of and what limitations arise, how reproducible the measurements are and what additional information can be gained from them for different sample types. As a further aspect it will be shown how the described setup can be used for the study of aqueous systems in solution at sub-freezing conditions
Bodenkohlenstoffdaten Universitätswald Sailershausen
No full textDas Dataset enthält Bodenkohlenstoffdaten des Universitätswalds Sailershausen. Die Daten wurden 2024 in einem 400 m mal 400 m Raster erhoben. Das Beprobungsraster wurde über die bestehenden Forstinventurpunkte des Forstbetriebs gelegt, um eine Folgebeprobung zu vereinfachen. Die Bodenkohlenstoffbeprobung erfolgte in drei Tiefenstufen (0-5 cm, 5-10 cm und 10-30 cm), analog zur Bodenzustandserhebung Wald BZE III. Die Profilansprache erfolgte nach der Bodenkundlichen Kartieranleitung KA 5. Die Laboranalysen wurden mit einem Elementar SoliTOC Cube durchgeführt. Folgende Parameter wurden erhoben: CN-Analyse (TIC, TOC, CN-Verhältnis, TC, ROC), Skelettanteil, Bodengefüge, Bodentyp.
Der Universitätswald Sailershausen ist der Forstbetrieb der Julius-Maximilians-Universität Würzburg. Der Forstbetrieb umfasst eine Fläche von 2346,4 ha, wobei sich der größere Teil nordwestlich von Haßfurt um das Dorf Sailershausen und ein kleinerer Teil südlich des Mains um das Gut Mariaburghausen befindet. Das Untersuchungsgebiet befindet sich in den Naturräumen „Hesselbacher Waldland“ und „Steigerwaldvorland“. Morphologisch ist es durch das Tal der Wässernach geprägt. Der Universitätswald Sailershausen befindet sich geologisch im Übergangsbereich von Oberem Muschelkalk (mo) zu Unterem Keuper (ku) und ist durch zahlreiche kleinräumige geologische Wechsel geprägt. Die dominierenden Bodentypen sind auf Oberem Muschelkalk Braunerde-Terra fusca, Pararendzinen und Braunerde-Pararendzinen. Bei Lössauflagen finden sich Braunerden und Parabraunerden. Über Unterem Keuper finden sich vorwiegend Braunerden, untergeordnet auch Parabraunerden. Pseudovergleyte Subtypen treten flächig auf.
Das Dataset wurde im Rahmen des BMBF-Projekts „REKLINEU“ generiert.The dataset contains soil carbon data from the Sailershausen University Forest. The data was collected in 2024 using a 400 m by 400 m grid. The sampling grid was superimposed on the existing forest inventory points of the forestry operation in order to simplify follow-up sampling. Soil carbon sampling was carried out at three depth levels (0-5 cm, 5-10 cm, and 10-30 cm), analogous to the BZE III forest soil condition survey. The profile was assessed in accordance with soil mapping guideline KA 5. Laboratory analyses were performed using an Elementar SoliTOC Cube. The following parameters were recorded: CN analysis (TIC, TOC, CN ratio, TC, ROC), skeleton content, soil structure, soil type.
The Sailershausen University Forest is the forestry operation of Julius Maximilian University of Würzburg. The forestry operation covers an area of 2,346.4 hectares, with the larger part located northwest of Haßfurt around the village of Sailershausen and a smaller part south of the Main River around the Mariaburghausen estate. The study area is located in the “Hesselbacher Waldland” and “Steigerwaldvorland” natural areas. Morphologically, it is characterized by the Wässernach valley. Geologically, the Sailershausen University Forest is located in the transition zone between the Upper Muschelkalk (mo) and Lower Keuper (ku) and is characterized by numerous small-scale geological changes. The dominant soil types above Upper Muschelkalk are Calcic Luvisols, and Calcaric Regosols. Cambisols and Calcic Luvisols are found on loess deposits. Lower Keuper is predominantly covered by Cambisols, with Calcic Luvisols also occurring to a lesser extent. Gleyic subtypes occur over large areas.
The dataset was generated in the frame of the FMER project “REKLINEU”
Assessment of the Viability and Mechanoresponsiveness of hMSC-TERT Printed with Bioinert, Thermoresponsive Hydrogels
No full textDuring three-dimensional (3D) bioprinting, the integration of living cells into hydrogel matrices results in complex biophysicochemical interactions between viscosity, shear stress, and temperature, critically influencing the structural and functional integrity of the resulting constructs. This study delves into the short-term biological ramifications of 3D extrusion printing of telomerase-immortalized human mesenchymal stromal cells (hMSC-TERT) embedded in bioinert hydrogels. Pluronic F127 and custom-synthesized poly(2-methyl-2-oxazoline)-block-poly(2-n-propyl-2-oxazine) (POx/POzi) are synthetic, block copolymers that create shear-thinning, physically crosslinked hydrogels that were used for this study. The rheological properties of the cell-free hydrogels and cell-laden bioinks were examined, revealing that they exhibited comparable behavior. Contrary to the original hypotheses, a key finding of this research is the reduction in cell viability (up to 50 %) within 24 h post-printing, a trend consistently observed across varying initial conditions. The relative expression levels of the mechanoresponsive genes FOS and PTGS2 were increased, partly due to the suspension and incubation of the cells in both hydrogels. Only FOS was significantly upregulated in some cases because of the printing process after 2 and 4 h of incubation. These insights highlight the potential of using POx/POzi hydrogel as a matrix in 3D bioprinting, particularly for depositing hMSC-TERT into structures with vasculature-mimicking scaffolds or scaffolds designed for bone regeneration
Structural, electronic, and magnetic properties of europium films
No full textRaw data used for the manuscript: "Structural, electronic, and magnetic properties of Europium films epitaxially grown on W(110)" published in Physical Review B.
This study presents a detailed spin-polarized scanning tunneling microscopy (SP-STM) analysis on the structural, electronic and magnetic properties on Europium (Eu) films epitaxially grown on a W(110) substrate.
Utilizing optimized growth parameters, we conduct a thickness-dependent series ranging from the sub-monolayer regime to films as thick as 650 AL.
Atomically resolved STM images of a 130 AL Eu film unveil lateral periodic sequences of bcc(110)-ordered dislocation lines sandwiched between adjacent hcp(0001) segments, effectively relieving stress within the films.
These dislocation lines exhibit a periodicity of p_topo = (3.36 ± 0.11) nm.
Tunneling spectroscopy reveals that the surface of Eu films hosts a pronounced double-peak structure at about U_bias ≈ +0.30 V and ≈ +0.48 V, corresponding to unoccupied sample states.
It is interpreted as an exchange-split dz^2-like surface state which remains robust even within the bcc(110) structure of the dislocation lines.
Magnetically sensitive data reveal a spin spiral with a surface periodicity of p_mag = (2.76 ± 0.19) nm.
The results are discussed in terms of bulk-terminated spin spirals in hcp Eu which propagate along ⟨-1-123⟩ directions in the surface-near region.We acknowledge financial support by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) through Project No. 510676484 (GZ: BO 1468/29-1) and under Germany’s Excellence Strategy through the Würzburg– Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter, ct.qmat (EXC 2147, Project No. 390858490).Please read the "README.txt" file for further information
The Automatic Multimodal Robotic Storyteller
No full textThis repository contains the full implementation of the Automatic Multimodal Robotic Storyteller for the Pepper robot. The system enables Pepper to perform any written story using multimodal storytelling elements such as emotional body language, emotion-inducing music, and dynamic colored lighting. It consists of two main modules: an annotator module that enriches story texts with emotional metadata, and a player module that translates these annotations into expressive robotic behavior.
The pipeline has been empirically developed based on extensive research into emotional storytelling and robotic expressivity. It is designed to be easily adaptable to a wide variety of stories, allowing users to convert plain text into compelling robotic performances with minimal effort.
This tool aims to support the growing interest in social robots as engaging storytelling agents and provides a practical foundation for future applications and research in the field, as internet connection is only needed for the annotator but not the player
Artificial Gauge Fields and Dimensions in a Polariton Hofstadter Ladder
No full textSpectrometer files taken with an Andor Shamrock 750 spectrograph and an Andor iKon M CCD. The package contains all raw experimental data used in our paper "Artificial Gauge Fields and Dimensions in a Polariton Hofstadter Ladder" (https://arxiv.org/abs/2506.13521). The files can be read using the python repository "sifreader".The Würzburg group acknowledges financial support by the German Research Foundation (DFG) under Germany's Excellence Strategy-EXC2147 "ct.qmat" (project id 390858490) and within the project KL3124/3.1. T.C.H.L. was supported by the Singapore Ministry of Education (MOE) grant (MOE-MOET32023-0003) "Quantum Geometric Advantage"
Social Robots Against Bullying - Supplemental Material
No full textBullying in early childhood remains an underexplored challenge despite its early manifestation and lasting impact. Social stories are a proven tool to teach appropriate behavior in young children. Social robots as storytellers offer an engaging medium, i.a. for children, for such interventions due to their embodied, interactive capabilities. This paper investigates the potential of a robot telling a social story as an anti-bullying intervention. Across two studies, we compared storytelling with an embodied robotic storyteller to a loudspeaker (Study I) and linear versus interactive robotic storytelling (Study II). Results from Study I showed that while story recognition and transportation did not differ significantly, robotic storytelling elicited significantly more empathy. Study II revealed that interactivity notably improved bullying awareness, though it did not affect empathy or transportation. These findings suggest that robotic storytelling - especially when interactive - can be an effective, engaging tool for early bullying interventions.
In this repository, the supplemental material to the studies, namely the story's text and the utilized questionnaires alongside the respective answer options, are provided
The influence of albedo on Mesoarchaean climate - global tas temperature
No full textClimate change in the Mesoarchaean potentially played a pivotal role in facilitating gold mobilisation and deposition, ultimately contributing to the formation of the Witwatersrand gold province in the Kaapvaal Craton (South Africa) – the world’s largest known gold province. Almost all of the gold there occurs in the 2.90 – 2.79 Ga Central Rand Group, whereas the underlying 2.95 - 2.91 Ga West Rand Group, despite similar sedimentology, is essentially barren. This has been explained by differing degrees of chemical weathering, with intense weathering in Central Rand Group times having facilitated gold leaching from the Archaean hinterland. However, the drivers of this climatic change remain unsolved. To investigate this, we performed 140 simulations using the Planet Simulator, an Earth system model of intermediate complexity. We systematically assessed the effects of varying land distributions (diagonal, central, polar), land surface fractions (8–28 %), atmospheric CO₂-equivalent concentrations (3–30 %), and surface albedo (0.15–0.30). In addition to the expected strong dependence of global mean temperature on atmospheric greenhouse gas concentration, our results show reduced seasonality at higher atm. CO₂-equivalents. Increasing land area generally leads to cooling, except at low CO2-equivalent concentrations (3-5 %) and low albedo (<0.2). When land exceeds ~13 % of total Earth’s surface, it starts to have a pronounced effect on global climate. Among the spatial configurations, diagonal land distribution shows the highest climate sensitivity. The climatic shift around 2.9 Ga may be linked to emergence of extensive low-albedo (<0.2) surfaces (e.g., mafic/ultramafic rocks) and/or to the latitudinal drift of the Kaapvaal Craton into a more radiatively sensitive zone.
This dataset contains global 2-meter above the ground temperature (tas) at a horizontal resolution of T21 (64 x 32 grid points). The data show the global effects of surface albedo.
In this experiment, only the diagonal land distribution with different fractions was used, while the surface albedo was systematically varied to assess its climatic impact. The prescribed albedo values were 0.15, 0.20, 0.25 and 0.30.
All simulations were performed using the Planet Simulator (PlaSim; Freadrich et al. 2005), an intermediate-complexity general circulation model. Postprocessing was conducted using PlaSim’s integrated postprocessor. The resulting data are provided in NetCDF format, representing 50-year simulations with the variable tas defined on the dimensions [long(64), lat(32), time (18263)]