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2017


Probabilistic Line Searches for Stochastic Optimization
Probabilistic Line Searches for Stochastic Optimization

Mahsereci, M., Hennig, P.

Journal of Machine Learning Research, 18(119):1-59, November 2017 (article)

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link (url) Project Page [BibTex]

2017


link (url) Project Page [BibTex]


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Convergence Analysis of Deterministic Kernel-Based Quadrature Rules in Misspecified Settings

Kanagawa, M., Sriperumbudur, B. K., Fukumizu, K.

Arxiv e-prints, arXiv:1709.00147v1 [math.NA], 2017 (article)

Abstract
This paper presents convergence analysis of kernel-based quadrature rules in misspecified settings, focusing on deterministic quadrature in Sobolev spaces. In particular, we deal with misspecified settings where a test integrand is less smooth than a Sobolev RKHS based on which a quadrature rule is constructed. We provide convergence guarantees based on two different assumptions on a quadrature rule: one on quadrature weights, and the other on design points. More precisely, we show that convergence rates can be derived (i) if the sum of absolute weights remains constant (or does not increase quickly), or (ii) if the minimum distance between distance design points does not decrease very quickly. As a consequence of the latter result, we derive a rate of convergence for Bayesian quadrature in misspecified settings. We reveal a condition on design points to make Bayesian quadrature robust to misspecification, and show that, under this condition, it may adaptively achieve the optimal rate of convergence in the Sobolev space of a lesser order (i.e., of the unknown smoothness of a test integrand), under a slightly stronger regularity condition on the integrand.

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arXiv [BibTex]

arXiv [BibTex]


Early Stopping Without a Validation Set
Early Stopping Without a Validation Set

Mahsereci, M., Balles, L., Lassner, C., Hennig, P.

arXiv preprint arXiv:1703.09580, 2017 (article)

Abstract
Early stopping is a widely used technique to prevent poor generalization performance when training an over-expressive model by means of gradient-based optimization. To find a good point to halt the optimizer, a common practice is to split the dataset into a training and a smaller validation set to obtain an ongoing estimate of the generalization performance. In this paper we propose a novel early stopping criterion which is based on fast-to-compute, local statistics of the computed gradients and entirely removes the need for a held-out validation set. Our experiments show that this is a viable approach in the setting of least-squares and logistic regression as well as neural networks.

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link (url) Project Page Project Page [BibTex]


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Krylov Subspace Recycling for Fast Iterative Least-Squares in Machine Learning

Roos, F. D., Hennig, P.

arXiv preprint arXiv:1706.00241, 2017 (article)

Abstract
Solving symmetric positive definite linear problems is a fundamental computational task in machine learning. The exact solution, famously, is cubicly expensive in the size of the matrix. To alleviate this problem, several linear-time approximations, such as spectral and inducing-point methods, have been suggested and are now in wide use. These are low-rank approximations that choose the low-rank space a priori and do not refine it over time. While this allows linear cost in the data-set size, it also causes a finite, uncorrected approximation error. Authors from numerical linear algebra have explored ways to iteratively refine such low-rank approximations, at a cost of a small number of matrix-vector multiplications. This idea is particularly interesting in the many situations in machine learning where one has to solve a sequence of related symmetric positive definite linear problems. From the machine learning perspective, such deflation methods can be interpreted as transfer learning of a low-rank approximation across a time-series of numerical tasks. We study the use of such methods for our field. Our empirical results show that, on regression and classification problems of intermediate size, this approach can interpolate between low computational cost and numerical precision.

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link (url) Project Page [BibTex]


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Chemically active colloids near osmotic-responsive walls with surface-chemistry gradients

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

Journal of Physics: Condensed Matter, 29, IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Active colloids in the context of chemical kinetics

Oshanin, G., Popescu, M. N., Dietrich, S.

Journal of Physics A, 50, IOP Pub., Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Microbots Decorated with Silver Nanoparticles Kill Bacteria in Aqueous Media

Vilela, D., Stanton, M. M., Parmar, J., Sánchez, S.

ACS Applied Materials and Interfaces, 9(27):22093-22100, American Chemical Society, Washington, DC, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Measurement of second-order response without perturbation

Helden, L., Basu, U., Krüger, M., Bechinger, C.

EPL, 116(6), IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Swimming with a cage: low-Reynolds-number locomotion inside a droplet

Reigh, S., Zhu, L. L., Gallaire, F., Lauga, E.

Soft Matter, 13(17):3161-3173, Royal Society of Chemistry, Cambridge, UK, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Active Particle Accumulation at Boundaries: A Strategy to Measure Contact Angles

Simmchen, J., Malgaretti, P.

ChemNanoMat, 3(11):790-793, Wiley, Weinheim, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Two-fluid model for locomotion under self-confinement

Reigh, S., Lauga, E.

Physical Review Fluids, 2(9), American Physical Society, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Bubble gating in biological ion channels: A density functional theory study

Gu\ssmann, Florian, Roth, R.

Physical Review E, 95(6), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Nematic films at chemically structured surfaces

Silvestre, N. M., Telo da Gama, M. M., Tasinkevych, M.

Journal of Physics: Condensed Matter, 29(7), IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Nonadditive interactions and phase transitions in strongly confined colloidal systems

Vasilyev, O., Dietrich, S., Kondrat, S.

Soft Matter, 14(4):586-596, Royal Society of Chemistry, Cambridge, UK, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Platinum-free cobalt ferrite based micromotors for antibiotic removal

Parmar, J., Villa, K., Vilela, D., Sánchez, S.

Applied Materials Today, 9, pages: 605-611, Elsevier, Amsterdam, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Perils of ad hoc approximations for the activity function of chemically powered colloids

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

The European Physical Journal E, 40, EDP Sciences; Società Italiana di Fisica; Springer, Les Ulis; Bologna; Heidelberg, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Transient Casimir Forces from Quenches in Thermal and Active Matter

Rohwer, C. M., Kardar, M., Krüger, M.

Physical Review Letters, 118(1), American Physical Society, Woodbury, N.Y., 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Rotational motion of dimers of Janus particles

Majee, A.

European Physical Journal E, 40(3), Springer, Berlin, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Designing Micro- and Nanoswimmers for Specific Applications

Katuri, J., Ma, X., Stanton, M. M., Sanchez, S.

Accounts of Chemical Research, 50(1):2-11, American Chemical Society, Easton, Pa., 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Wedge wetting by electrolyte solutions

Mußotter, M., Bier, M.

Physical Review E, 96(3), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Effect of boundaries on vacuum field fluctuations and radiation-mediated interactions between atoms

Armata, F., Butera, S., Fiscelli, G., Incardone, R., Notararigo, V., Palacino, R., Passante, R., Rizzuto, L., Spagnolo, S.

Journal of Physics: Conference Series, 880, IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Smectic phases in ionic liquid crystals

Bartsch, H., Bier, M., Dietrich, S.

Journal of Physics: Condensed Matter, 29(46), IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Pushing Bacterial Biohybrids to In Vivo Applications

Stanton, M. M., Sánchez, S.

Trends in Biotechnology, 35(10):910-913, Elsevier Current Trends, Amsterdam, Netherlands, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Particles with nonlinear electric response: Suppressing van der Waals forces by an external field

Soo, H., Dean, D. S., Krüger, M.

Physical Review E, 95(1), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Electrolyte solutions at curved electrodes. I. Mesoscopic approach

Reindl, A., Bier, M., Dietrich, S.

The Journal of Chemical Physics, 146(15), American Institute of Physics, Woodbury, N.Y., 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Self-propelling micro-nanorobots: challenges and fututre perspectives in nanomedicine

Ma, X., Sánchez, S.

Nanomedicine, 12(12):1363-1367, Future Medicine Ltd, London, UK, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Salt-induced microheterogeneities in binary liquid mixtures

Bier, M., Mars, J., Li, H., Mezger, M.

Physical Review E, 96(2), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Forward-backward multiplicity correlations in proton-proton collisions from several GeV to LHC energies

Bravina, L., Bleibel, J., Emaus, R., Zabrodin, E.

EPJ Web of Conferences, 164, EDP Sciences, Les Ulis, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Key-lock colloids in a nematic liquid crystal

Silvestre, N. M., Tasinkevych, M.

Physical Review E, 95(1), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Fluctuation induced forces in critical films with disorder at their surfaces

Maciolek, A., Vasilyev, O., Dotsenko, V., Dietrich, S.

Journal of Statistical Mechanics: Theory and Experiment, Institute of Physics Publishing, Bristol, England, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Action at a distance in classical uniaxial ferromagnetic arrays

Abraham, D. B., Maciolek, A., Squarcini, A., Vasilyev, O.

Physical Review E, 96(4), American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Cooperative behavior of biased probes in crowded interacting systems

Vasilyev, O., Bénichou, O., Mej\’\ia-Monasterio, C., Weeks, E. R., Oshanin, G.

Soft Matter, 13(41):7617-7624, Royal Society of Chemistry, Cambridge, UK, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Nonequilibrium Fluctuational Quantum Electrodynamics: Heat Radiation, Heat Transfer, and Force

Bimonte, G., Emig, T., Kardar, M., Krüger, M.

Annual Review of Condensed Matter Physics, 8, pages: 119-143, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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A Gaussian theory for fluctuations in simple liquids

Krüger, M., Dean, D. S.

The Journal of Chemical Physics, 146(13), American Institute of Physics, Woodbury, N.Y., 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Critical Casimir interactions between colloids around the critical point of binary solvents

Stuij, S. G., Labbe-Laurent, M., Kodger, T. E., Maciolek, A., Schall, P.

Soft Matter, 13(31):5233-5249, Royal Society of Chemistry, Cambridge, UK, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Bio-catalytic mesoporous Janus nano-motors powered by catalase enzyme

Ma, X., Sánchez, S.

Tetrahedron, 73(33):4883-4886, Elsevier Science, Kidlington, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Basic features of proton-proton interactions at ultra-relativistic energies and RFT-based quark-gluon string model

Zabrodin, E., Bravina, L., Bleibel, J.

EPJ Web of Conferences, 164, EDP Sciences, Les Ulis, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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The modified Langevin description for probes in a nonlinear medium

Krüger, M., Maes, C.

Journal of Physics: Condensed Matter, 29(6), IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Smoluchowski rate for diffusion-controlled reactions of molecules with antenna

Vasilyev, O., Lizana, L., Oshanin, G.

Journal of Physics A, 50(26), IOP Pub., Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Model microswimmers in channels with varying cross section

Malgaretti, P., Stark, H.

The Journal of Chemical Physics, 146(17), American Institute of Physics, Woodbury, N.Y., 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Heat radiation and transfer for point particles in arbitrary geometries

Asheichyk, K., Müller, B., Krüger, M.

Physical Review B, 96(15), American Physical Society, Woodbury, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Surface induced smectic order in ionic liquids - an X-ray reflectivity study of [C(22)C(1)im](+)[NTf2](-)

Mars, J., Hou, B., Weiss, H., Li, H., Konovalov, O., Festersen, S., Murphy, B. M., Rütt, U., Bier, M., Mezger, M.

Physical Chemistry Chemical Physics, 19(39):26651-26661, Royal Society of Chemistry, Cambridge, England, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Efficiency of analytical and sampling-based uncertainty propagation in intensity-modulated proton therapy

Wahl, N., Hennig, P., Wieser, H. P., Bangert, M.

Physics in Medicine & Biology, 62(14):5790-5807, 2017 (article)

Abstract
The sensitivity of intensity-modulated proton therapy (IMPT) treatment plans to uncertainties can be quantified and mitigated with robust/min-max and stochastic/probabilistic treatment analysis and optimization techniques. Those methods usually rely on sparse random, importance, or worst-case sampling. Inevitably, this imposes a trade-off between computational speed and accuracy of the uncertainty propagation. Here, we investigate analytical probabilistic modeling (APM) as an alternative for uncertainty propagation and minimization in IMPT that does not rely on scenario sampling. APM propagates probability distributions over range and setup uncertainties via a Gaussian pencil-beam approximation into moments of the probability distributions over the resulting dose in closed form. It supports arbitrary correlation models and allows for efficient incorporation of fractionation effects regarding random and systematic errors. We evaluate the trade-off between run-time and accuracy of APM uncertainty computations on three patient datasets. Results are compared against reference computations facilitating importance and random sampling. Two approximation techniques to accelerate uncertainty propagation and minimization based on probabilistic treatment plan optimization are presented. Runtimes are measured on CPU and GPU platforms, dosimetric accuracy is quantified in comparison to a sampling-based benchmark (5000 random samples). APM accurately propagates range and setup uncertainties into dose uncertainties at competitive run-times (GPU ##IMG## [http://ej.iop.org/images/0031-9155/62/14/5790/pmbaa6ec5ieqn001.gif] {$\leqslant {5}$} min). The resulting standard deviation (expectation value) of dose show average global ##IMG## [http://ej.iop.org/images/0031-9155/62/14/5790/pmbaa6ec5ieqn002.gif] {$\gamma_{{3}\% / {3}~{\rm mm}}$} pass rates between 94.2% and 99.9% (98.4% and 100.0%). All investigated importance sampling strategies provided less accuracy at higher run-times considering only a single fraction. Considering fractionation, APM uncertainty propagation and treatment plan optimization was proven to be possible at constant time complexity, while run-times of sampling-based computations are linear in the number of fractions. Using sum sampling within APM, uncertainty propagation can only be accelerated at the cost of reduced accuracy in variance calculations. For probabilistic plan optimization, we were able to approximate the necessary pre-computations within seconds, yielding treatment plans of similar quality as gained from exact uncertainty propagation. APM is suited to enhance the trade-off between speed and accuracy in uncertainty propagation and probabilistic treatment plan optimization, especially in the context of fractionation. This brings fully-fledged APM computations within reach of clinical application.

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link (url) [BibTex]

link (url) [BibTex]


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Analytical probabilistic modeling of RBE-weighted dose for ion therapy

Wieser, H., Hennig, P., Wahl, N., Bangert, M.

Physics in Medicine and Biology (PMB), 62(23):8959-8982, 2017 (article)

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link (url) [BibTex]

link (url) [BibTex]


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Onset of anomalous diffusion in colloids confined to quasimonolayers

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

Physical Review E, 95, American Physical Society, Melville, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Viscosity of a sheared correlated (near-critical) model fluid in confinement

Rohwer, C. M., Gambassi, A., Krüger, M.

Journal of Physics: Condensed Matter, 29(33), IOP Publishing, Bristol, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Many-body heat radiation and heat transfer in the presence of a nonabsorbing background medium

Müller, B., Incardone, R., Antezza, M., Emig, T., Krüger, M.

Physical Review B, 95(8), American Physical Society, Woodbury, NY, 2017 (article)

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DOI [BibTex]

DOI [BibTex]


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Electrolyte solutions at curved electrodes. II. Microscopic approach

Reindl, A., Bier, M., Dietrich, S.

The Journal of Chemical Physics, 146(15), American Institute of Physics, Woodbury, N.Y., 2017 (article)

icm

DOI [BibTex]

DOI [BibTex]