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2020


Interface-mediated spontaneous symmetry breaking and mutual communication between drops containing chemically active particles
Interface-mediated spontaneous symmetry breaking and mutual communication between drops containing chemically active particles

Singh, D., Domínguez, A., Choudhury, U., Kottapalli, S., Popescu, M., Dietrich, S., Fischer, P.

Nature Communications, 11(2210), May 2020 (article)

Abstract
Symmetry breaking and the emergence of self-organized patterns is the hallmark of com- plexity. Here, we demonstrate that a sessile drop, containing titania powder particles with negligible self-propulsion, exhibits a transition to collective motion leading to self-organized flow patterns. This phenomenology emerges through a novel mechanism involving the interplay between the chemical activity of the photocatalytic particles, which induces Mar- angoni stresses at the liquid–liquid interface, and the geometrical confinement provided by the drop. The response of the interface to the chemical activity of the particles is the source of a significantly amplified hydrodynamic flow within the drop, which moves the particles. Furthermore, in ensembles of such active drops long-ranged ordering of the flow patterns within the drops is observed. We show that the ordering is dictated by a chemical com- munication between drops, i.e., an alignment of the flow patterns is induced by the gradients of the chemicals emanating from the active particles, rather than by hydrodynamic interactions.

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link (url) DOI [BibTex]


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Automatic Discovery of Interpretable Planning Strategies

Skirzyński, J., Becker, F., Lieder, F.

May 2020 (article) Submitted

Abstract
When making decisions, people often overlook critical information or are overly swayed by irrelevant information. A common approach to mitigate these biases is to provide decisionmakers, especially professionals such as medical doctors, with decision aids, such as decision trees and flowcharts. Designing effective decision aids is a difficult problem. We propose that recently developed reinforcement learning methods for discovering clever heuristics for good decision-making can be partially leveraged to assist human experts in this design process. One of the biggest remaining obstacles to leveraging the aforementioned methods for improving human decision-making is that the policies they learn are opaque to people. To solve this problem, we introduce AI-Interpret: a general method for transforming idiosyncratic policies into simple and interpretable descriptions. Our algorithm combines recent advances in imitation learning and program induction with a new clustering method for identifying a large subset of demonstrations that can be accurately described by a simple, high-performing decision rule. We evaluate our new AI-Interpret algorithm and employ it to translate information-acquisition policies discovered through metalevel reinforcement learning. The results of three large behavioral experiments showed that the provision of decision rules as flowcharts significantly improved people’s planning strategies and decisions across three different classes of sequential decision problems. Furthermore, a series of ablation studies confirmed that our AI-Interpret algorithm was critical to the discovery of interpretable decision rules and that it is ready to be applied to other reinforcement learning problems. We conclude that the methods and findings presented in this article are an important step towards leveraging automatic strategy discovery to improve human decision-making.

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Automatic Discovery of Interpretable Planning Strategies The code for our algorithm and the experiments is available [BibTex]


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Advancing Rational Analysis to the Algorithmic Level

Lieder, F., Griffiths, T. L.

Behavioral and Brain Sciences, 43, E27, March 2020 (article)

Abstract
The commentaries raised questions about normativity, human rationality, cognitive architectures, cognitive constraints, and the scope or resource rational analysis (RRA). We respond to these questions and clarify that RRA is a methodological advance that extends the scope of rational modeling to understanding cognitive processes, why they differ between people, why they change over time, and how they could be improved.

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Advancing rational analysis to the algorithmic level DOI [BibTex]

Advancing rational analysis to the algorithmic level DOI [BibTex]


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Learning to Overexert Cognitive Control in a Stroop Task

Bustamante, L., Lieder, F., Musslick, S., Shenhav, A., Cohen, J.

Febuary 2020, Laura Bustamante and Falk Lieder contributed equally to this publication. (article) In revision

Abstract
How do people learn when to allocate how much cognitive control to which task? According to the Learned Value of Control (LVOC) model, people learn to predict the value of alternative control allocations from features of a given situation. This suggests that people may generalize the value of control learned in one situation to other situations with shared features, even when the demands for cognitive control are different. This makes the intriguing prediction that what a person learned in one setting could, under some circumstances, cause them to misestimate the need for, and potentially over-exert control in another setting, even if this harms their performance. To test this prediction, we had participants perform a novel variant of the Stroop task in which, on each trial, they could choose to either name the color (more control-demanding) or read the word (more automatic). However only one of these tasks was rewarded, it changed from trial to trial, and could be predicted by one or more of the stimulus features (the color and/or the word). Participants first learned colors that predicted the rewarded task. Then they learned words that predicted the rewarded task. In the third part of the experiment, we tested how these learned feature associations transferred to novel stimuli with some overlapping features. The stimulus-task-reward associations were designed so that for certain combinations of stimuli the transfer of learned feature associations would incorrectly predict that more highly rewarded task would be color naming, which would require the exertion of control, even though the actually rewarded task was word reading and therefore did not require the engagement of control. Our results demonstrated that participants over-exerted control for these stimuli, providing support for the feature-based learning mechanism described by the LVOC model.

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Learning to Overexert Cognitive Control in a Stroop Task DOI [BibTex]

Learning to Overexert Cognitive Control in a Stroop Task DOI [BibTex]


Toward a Formal Theory of Proactivity
Toward a Formal Theory of Proactivity

Lieder, F., Iwama, G.

January 2020 (article) Submitted

Abstract
Beyond merely reacting to their environment and impulses, people have the remarkable capacity to proactively set and pursue their own goals. But the extent to which they leverage this capacity varies widely across people and situations. The goal of this article is to make the mechanisms and variability of proactivity more amenable to rigorous experiments and computational modeling. We proceed in three steps. First, we develop and validate a mathematically precise behavioral measure of proactivity and reactivity that can be applied across a wide range of experimental paradigms. Second, we propose a formal definition of proactivity and reactivity, and develop a computational model of proactivity in the AX Continuous Performance Task (AX-CPT). Third, we develop and test a computational-level theory of meta-control over proactivity in the AX-CPT that identifies three distinct meta-decision-making problems: intention setting, resolving response conflict between intentions and automaticity, and deciding whether to recall context and intentions into working memory. People's response frequencies in the AX-CPT were remarkably well captured by a mixture between the predictions of our models of proactive and reactive control. Empirical data from an experiment varying the incentives and contextual load of an AX-CPT confirmed the predictions of our meta-control model of individual differences in proactivity. Our results suggest that proactivity can be understood in terms of computational models of meta-control. Our model makes additional empirically testable predictions. Future work will extend our models from proactive control in the AX-CPT to proactive goal creation and goal pursuit in the real world.

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Toward a formal theory of proactivity DOI Project Page [BibTex]


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Axisymmetric spheroidal squirmers and self-diffusiophoretic particles

Pöhnl, R., Popescu, M. N., Uspal, W. E.

Journal of Physics: Condensed Matter, 32(16), IOP Publishing, Bristol, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Tracer diffusion on a crowded random Manhattan lattice

Mej\’\ia-Monasterio, C., Nechaev, S., Oshanin, G., Vasilyev, O.

New Journal of Physics, 22(3), IOP Publishing, Bristol, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Analytical classical density functionals from an equation learning network

Lin, S., Martius, G., Oettel, M.

The Journal of Chemical Physics, 152(2):021102, 2020, arXiv preprint \url{https://arxiv.org/abs/1910.12752} (article)

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Preprint_PDF DOI [BibTex]

Preprint_PDF DOI [BibTex]


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Wetting transitions on soft substrates

Napiorkowski, M., Schimmele, L., Dietrich, S.

{EPL}, 129(1), EDP Science, Les-Ulis, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Blessing and Curse: How a Supercapacitor Large Capacitance Causes its Slow Charging

Lian, C., Janssen, M., Liu, H., van Roij, R.

Physical Review Letters, 124(7), American Physical Society, Woodbury, N.Y., 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Interplay of quenching temperature and drift in Brownian dynamics

Khalilian, H., Nejad, M. R., Moghaddam, A. G., Rohwer, C. M.

EPL, 128(6), EDP Science, Les-Ulis, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Fractal-seaweeds type functionalization of graphene

Amsharov, K., Sharapa, D. I., Vasilyev, O. A., Martin, O., Hauke, F., Görling, A., Soni, H., Hirsch, A.

Carbon, 158, pages: 435-448, Elsevier, Amsterdam, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Effective pair interaction of patchy particles in critical fluids

Farahmand Bafi, N., Nowakowski, P., Dietrich, S.

The Journal of Chemical Physics, 152(11), American Institute of Physics, Woodbury, N.Y., 2020 (article)

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DOI [BibTex]


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Cassie-Wenzel transition of a binary liquid mixture on a nanosculptured surface

Singh, S. L., Schimmele, L., Dietrich, S.

Physical Review E, 101(5), American Physical Society, Melville, NY, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Energy storage in steady states under cyclic local energy input

Zhang, Y., Holyst, R., Maciolek, A.

Physical Review E, 101(1), American Physical Society, Melville, NY, 2020 (article)

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DOI [BibTex]

DOI [BibTex]


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Numerical simulations of self-diffusiophoretic colloids at fluid interfaces

Peter, T., Malgaretti, P., Rivas, N., Scagliarini, A., Harting, J., Dietrich, S.

Soft Matter, 16(14):3536-3547, Royal Society of Chemistry, Cambridge, UK, 2020 (article)

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DOI [BibTex]

DOI [BibTex]

2016


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Self-diffusiophoresis of chemically active colloids

Popescu, M. N., Uspal, W. E., Dietrich, S.

The European Physical Journal Special Topics, 225(11-12):2189-2206, 2016 (article)

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2016


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Perpetual superhydrophobicity

Giacomello, A., Schimmele, L., Dietrich, S., Tasinkevych, M.

Soft Matter, 12, pages: 8927-8934, Royal Society of Chemistry, Cambridge, UK, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Molecular dynamics simulation of a binary mixture near the lower critical point

Pousaneh, F., Edholm, O., Maciolek, A.

The Journal of Chemical Physics, 145(1), American Institute of Physics, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]


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Effective Interaction between Active Colloids and Fluid Interfaces Induced by Marangoni Flows

Dom\’\inguez, A., Malgaretti, P., Popescu, M. N., Dietrich, S.

Physical Review Letters, 116, American Physical Society, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]


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Dynamics of Novel Photoactive AgCl Microstars and Their Environmental Applications

Simmchen, J., Baeza, A., Miguel-Lopez, A., Stanton, M. M., Vallet-Regi, M., Ruiz-Molina, D., Sánchez, S.

ChemNanoMat, 3(1):65-71, Wiley, Weinheim, 2016 (article)

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DOI [BibTex]


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Wetting hysteresis induced by nanodefects

Giacomello, A., Schimmele, L., Dietrich, S.

Proceedings of the National Academy of Sciences of the United States of America, 113(3):E262-E271, National Academy of Sciences, Washington, D.C., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Three-phase contact line and line tension of electrolyte solutions in contact with charged substrates

Ibagon, I., Bier, M., Dietrich, S.

Journal of Physics: Condensed Matter, 28(24), IOP Publishing, Bristol, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Smart biosensors for multiplexed and fully integrated point-of-care diagnostics

Romeo, A., Leung, T. S., Sanchez, S.

Lab on a Chip, 16(11):1957-1961, Royal Society of Chemistry, Cambridge, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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The sequential activation of the mitotic microtubule assembly pathways favors bipolar spindle formation

Cavazza, T., Malgaretti, P., Vernos, I.

Molecular Biology of the Cell, 27(19):2935-2945, American Society for Cell Biology, 2016 (article)

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DOI [BibTex]


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Entropically induced asymmetric passage times of charged tracers across corrugated channels

Malgaretti, P., Pagonabarraga, I., Rubi, J. M.

The Journal of Chemical Physics, 144(3), American Institute of Physics, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Diffusion im Zentrifugalpotential

Totikos, Vangelis

Universität Stuttgart, Stuttgart, 2016 (mastersthesis)

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[BibTex]

[BibTex]


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Topographical pathways guide chemical microswimmers

Simmchen, J., Katuri, J., Uspal, W., Popescu, M. N., Tasinkevych, M., Sanchez, S.

Nature Communications, 7, Nature Publishing Group, London, 2016 (article)

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Fluctuational electrodynamics for nonlinear media

Soo, H., Krüger, M.

EPL, 115(4), EDP Science, Les-Ulis, 2016 (article)

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DOI [BibTex]


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Poisson-Boltzmann study of the effective electrostatic interaction between colloids at an electrolyte interface

Majee, A., Bier, M., Dietrich, S.

The Journal of Chemical Physics, 145(6), American Institute of Physics, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]


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Bubble-Free Propulsion of Ultrasmall Tubular Nanojets Powered by Biocatalytic Reactions

Ma, X., Hortelao, A. C., Miquel-Lopez, A., Sanchez, S.

Journal of the American Chemical Society, 138(42):13782-13785, American Chemical Society, Washington, DC, 2016 (article)

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DOI [BibTex]


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Wetting and orientation of catalytic Janus colloids at the surface of water

Wang, X., In, M., Blanc, C., Malgaretti, P., Nobilia, M., Stocco, A.

Faraday Discussions, 191, pages: 305-324, Royal Society of Chemistry, London, 2016 (article)

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DOI [BibTex]


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Collective dynamics of chemically active particles trapped at a fluid interface

Dom\’\inguez, A., Malgaretti, P., Popescu, M. N., Dietrich, S.

Soft Matter, 12(40):8398-8406, Royal Society of Chemistry, Cambridge, UK, 2016 (article)

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DOI [BibTex]


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Guiding Catalytically Active Particles with Chemically Patterned Surfaces

Uspal, W. E., Popescu, M. N., Dietrich, S., Tasinkevych, M.

Physical Review Letters, 117(4), American Physical Society, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]


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Structure and dynamics of binary liquid mixtures near their continuous demixing transitions

Roy, S., Höfling, F., Dietrich, S.

The Journal of Chemical Physics, 145(4), American Institute of Physics, Woodbury, N.Y., 2016 (article)

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DOI [BibTex]


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A dynamic DFT approach to generalized diffusion equations in a system with long-ranged and hydrodynamic interactions

Bleibel, J., Dominguez, A., Oettel, M.

Journal of Physics: Condensed Matter, 28(24), IOP Publishing, Bristol, 2016 (article)

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DOI [BibTex]


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Rectification and Non-Gaussian Diffusion in Heterogeneous Media

Malgaretti, P., Pagonabarraga, I., Rubi, J. M.

Entropy, 18(11), Molecular Diversity Preservation International, Basel, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Lateral critical Casimir force in two\textendashdimensional inhomogeneous Ising strip. Exact results

Nowakowski, P., Napiorkowski, M.

The Journal of Chemical Physics, 144(21), 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Tailoring three-dimensional architectures by rolled-up nanotechnology for mimicking microvasculatures

Arayanarakool, R., Meyer, A. K., Helbig, L., Sanchez, S., Schmidt, O. G.

Lab on a Chip, 15(14):2981-2989, Royal Society of Chemistry, Cambridge, 2016 (article)

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DOI [BibTex]


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Flexible sensors for biomedical technology

Vilela, D., Romeo, A., Sanchez, S.

Lab on a Chip, 16(3):402-408, 2016 (article)

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DOI [BibTex]


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Mechanical stability of bipolar spindle assembly

Malgaretti, P., Muhuri, S.

EPL, 115(2), EDP Science, Les-Ulis, 2016 (article)

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DOI [BibTex]

DOI [BibTex]


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Reversed Janus micro/nanomotors with internal chemical engine

Ma, X., Jang, S., Popescu, M. N., Uspal, W. E., Miguel-López, A., Hahn, K., Kim, D., Sanchez, S.

ACS Nano, 10(9):8751-8759, American Chemical Society, Washington, DC, 2016 (article)

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DOI [BibTex]


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Driven colloidal fluids: construction of dynamical density functional theories from exactly solvable limits

Scacchi, A., Krüger, M., Brader, J. M.

Journal of Physics: Condensed Matter, 28(24), IOP Publishing, Bristol, 2016 (article)

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DOI [BibTex]


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Flight of a heavy particle nonlinearly coupled to a quantum bath

Maghrebi, M. F., Krüger, M., Kardar, M.

Physical Review B, 93(1), American Physical Society, Woodbury, NY, 2016 (article)

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DOI [BibTex]


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Critical Casimir forces between defects in the 2D Ising model

Nowakowski, P., Maciolek, A., Dietrich, S.

Journal of Physics A: Mathematical and Theoretical, 49(48), IOP Pub., Bristol, 2016 (article)

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Miniaturized soft bio-hybrid robotics: a step forward into healthcare applications

Patino, T., Mestre, R., Sanchez, S.

Lab on a Chip, 16(19):3626-3630, Royal Society of Chemistry, Cambridge, 2016 (article)

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Characterizing anomalous diffusion in crowded polymer solutions and gels over five decades in time with variable-lengthscale fluorescence correlation spectroscopy

Banks, Daniel S, Tressler, Charmaine, Peters, Robert D, Höfling, Felix, Fradin, Cécile

Soft Matter, 12(18):4190-4203, Royal Society of Chemistry, Cambridge, UK, 2016 (article)

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DOI [BibTex]


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Slip Length Enhancement in Nanofluidic Flow using Nanotextured Superhydrophobic Surfaces

Heverhagen, Jonas, Tasinkevych, M., Rahman, A., Black, C.T., Checco, A.

Advanced Materials Interfaces, 3(17), Wiley-VCH, Weinheim, 2016 (article)

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Electromagnetic radiation in complex environments: Many body systems and background medium

Müller, Boris

Universität Stuttgart, Stuttgart, 2016 (mastersthesis)

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[BibTex]

[BibTex]


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Active colloids at fluid interfaces

Malgaretti, P., Popescu, M. N., Dietrich, S.

Soft Matter, 12(17):4007-4023, Royal Society of Chemistry, Cambridge, UK, 2016 (article)

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DOI [BibTex]

DOI [BibTex]