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2013


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Hybrid nanocolloids with programmed three-dimensional shape and material composition

Mark, A. G., Gibbs, J. G., Lee, T., Fischer, P.

NATURE MATERIALS, 12(9):802-807, 2013, Max Planck Press Release. (article)

Abstract
Tuning the optical(1,2), electromagnetic(3,4) and mechanical properties of a material requires simultaneous control over its composition and shape(5). This is particularly challenging for complex structures at the nanoscale because surface-energy minimization generally causes small structures to be highly symmetric(5). Here we combine low-temperature shadow deposition with nanoscale patterning to realize nanocolloids with anisotropic three-dimensional shapes, feature sizes down to 20 nm and a wide choice of materials. We demonstrate the versatility of the fabrication scheme by growing three-dimensional hybrid nanostructures that contain several functional materials with the lowest possible symmetry, and by fabricating hundreds of billions of plasmonic nanohelices, which we use as chiral metafluids with record circular dichroism and tunable chiroptical properties.

Max Planck Press Release.

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Video - Fabrication of Designer Nanostructures DOI [BibTex]


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Optimal control of reaching includes kinematic constraints

Mistry, M., Theodorou, E., Schaal, S., Kawato, M.

Journal of Neurophysiology, 2013, clmc (article)

Abstract
We investigate adaptation under a reaching task with an acceleration-based force field perturbation designed to alter the nominal straight hand trajectory in a potentially benign manner:pushing the hand of course in one direction before subsequently restoring towards the target. In this particular task, an explicit strategy to reduce motor effort requires a distinct deviation from the nominal rectilinear hand trajectory. Rather, our results display a clear directional preference during learning, as subjects adapted perturbed curved trajectories towards their initial baselines. We model this behavior using the framework of stochastic optimal control theory and an objective function that trades-of the discordant requirements of 1) target accuracy, 2) motor effort, and 3) desired trajectory. Our work addresses the underlying objective of a reaching movement, and we suggest that robustness, particularly against internal model uncertainly, is as essential to the reaching task as terminal accuracy and energy effciency.

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PDF [BibTex]

PDF [BibTex]


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im3shape: a maximum likelihood galaxy shear measurement code for cosmic gravitational lensing

Zuntz, J., Kacprzak, T., Voigt, L., Hirsch, M., Rowe, B., Bridle, S.

Monthly Notices of the Royal Astronomical Society, 434(2):1604-1618, Oxford University Press, 2013 (article)

ei

DOI [BibTex]

DOI [BibTex]


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Linear mixed models for genome-wide association studies

Lippert, C.

University of Tübingen, Germany, 2013 (phdthesis)

ei

[BibTex]

[BibTex]


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Perceiving Systems – Computers that see

Gehler, P. V.

2013 (mpi_year_book)

Abstract
Our research goal is to define in a mathematical precise way how visual perception works. We want to describe how intelligent systems understand images. To this end we study probabilistic models and statistical learning. Encoding prior knowledge about the world is complemented with automatic learning from training data. One aspect is being able to identify physical factors in images, such as lighting, geometry, and materials. Furthermore we want to automatically recognize and give names to objects and persons in images and understand the scene as a whole.

link (url) [BibTex]


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Estimating Human Pose with Flowing Puppets

Zuffi, S., Romero, J., Schmid, C., Black, M. J.

In IEEE International Conference on Computer Vision (ICCV), pages: 3312-3319, 2013 (inproceedings)

Abstract
We address the problem of upper-body human pose estimation in uncontrolled monocular video sequences, without manual initialization. Most current methods focus on isolated video frames and often fail to correctly localize arms and hands. Inferring pose over a video sequence is advantageous because poses of people in adjacent frames exhibit properties of smooth variation due to the nature of human and camera motion. To exploit this, previous methods have used prior knowledge about distinctive actions or generic temporal priors combined with static image likelihoods to track people in motion. Here we take a different approach based on a simple observation: Information about how a person moves from frame to frame is present in the optical flow field. We develop an approach for tracking articulated motions that "links" articulated shape models of people in adjacent frames trough the dense optical flow. Key to this approach is a 2D shape model of the body that we use to compute how the body moves over time. The resulting "flowing puppets" provide a way of integrating image evidence across frames to improve pose inference. We apply our method on a challenging dataset of TV video sequences and show state-of-the-art performance.

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pdf code data DOI Project Page Project Page Project Page [BibTex]

pdf code data DOI Project Page Project Page Project Page [BibTex]


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Magnetoelastic coupling in epitaxial cobalt ferrite/barium titanate heterostructures

Gräfe, J., Welke, M., Bern, F., Ziese, M., Denecke, R.

Journal of Magnetism and Magnetic Materials, 339, pages: 84-88, 2013 (article)

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DOI [BibTex]

DOI [BibTex]


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Chiral Colloidal Molecules And Observation of The Propeller Effect

Schamel, D., Pfeifer, M., Gibbs, J. G., Miksch, B., Mark, A. G., Fischer, P.

JOURNAL OF THE AMERICAN CHEMICAL SOCIETY, 135(33):12353-12359, 2013 (article)

Abstract
Chiral molecules play an important role in biological and chemical processes, but physical effects due to their symmetry-breaking are generally weak. Several physical chiral separation schemes which could potentially be useful, including the propeller effect, have therefore not yet been demonstrated at the molecular scale. However, it has been proposed that complex nonspherical colloidal particles could act as ``colloidal molecules{''} in mesoscopic model systems to permit the visualization of molecular phenomena that are otherwise difficult to observe. Unfortunately, it is difficult to synthesize such colloids because surface minimization generally favors the growth of symmetric particles. Here we demonstrate the production of large numbers of complex colloids with glancing angle physical vapor deposition. We use chiral colloids to demonstrate the Baranova and Zel'dovich (Baranova, N. B.; Zel'dovich, B. Y. Chem. Phys. Lett. 1978, 57, 435) propeller effect: the separation of a racemic mixture by application of a rotating field that couples to the dipole moment of the enantiomers and screw propels them in opposite directions. The handedness of the colloidal suspensions is monitored with circular differential light scattering. An exact solution for the colloid's propulsion is derived, and comparisons between the colloidal system and the corresponding effect at the molecular scale are made.

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Video - Nanospropellers DOI [BibTex]

Video - Nanospropellers DOI [BibTex]


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Maximizing Kepler science return per telemetered pixel: Detailed models of the focal plane in the two-wheel era

Hogg, D. W., Angus, R., Barclay, T., Dawson, R., Fergus, R., Foreman-Mackey, D., Harmeling, S., Hirsch, M., Lang, D., Montet, B. T., Schiminovich, D., Schölkopf, B.

arXiv:1309.0653, 2013 (techreport)

ei

link (url) [BibTex]

link (url) [BibTex]


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Accurate detection of differential RNA processing

Drewe, P., Stegle, O., Hartmann, L., Kahles, A., Bohnert, R., Wachter, A., Borgwardt, K. M., Rätsch, G.

Nucleic Acids Research, 41(10):5189-5198, 2013 (article)

ei

DOI [BibTex]

DOI [BibTex]


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Being small, being smart

Liu, Na

2013 (mpi_year_book)

Abstract
Metallic nanostructures feature plasmonic resonances which spatially confine light on the nanometer scale. In the ultimate limit of a single nanostructure, the electromagnetic field can be strongly concentrated in a volume of only a few hundred nm3 or less. We utilize such plasmonic focusing for hydrogen detection at the single particle level, which avoids any inhomogeneous broadening and statistical effects that would occur in sensors based on nanoparticle ensembles. This concept paves the road towards the observation of single catalytic processes in nanoreactors.

link (url) [BibTex]

link (url) [BibTex]


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Fusing visual and tactile sensing for 3-D object reconstruction while grasping

Ilonen, J., Bohg, J., Kyrki, V.

In IEEE International Conference on Robotics and Automation (ICRA), pages: 3547-3554, 2013 (inproceedings)

Abstract
In this work, we propose to reconstruct a complete 3-D model of an unknown object by fusion of visual and tactile information while the object is grasped. Assuming the object is symmetric, a first hypothesis of its complete 3-D shape is generated from a single view. This initial model is used to plan a grasp on the object which is then executed with a robotic manipulator equipped with tactile sensors. Given the detected contacts between the fingers and the object, the full object model including the symmetry parameters can be refined. This refined model will then allow the planning of more complex manipulation tasks. The main contribution of this work is an optimal estimation approach for the fusion of visual and tactile data applying the constraint of object symmetry. The fusion is formulated as a state estimation problem and solved with an iterative extended Kalman filter. The approach is validated experimentally using both artificial and real data from two different robotic platforms.

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DOI Project Page [BibTex]

DOI Project Page [BibTex]


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Maximizing Kepler science return per telemetered pixel: Searching the habitable zones of the brightest stars

Montet, B. T., Angus, R., Barclay, T., Dawson, R., Fergus, R., Foreman-Mackey, D., Harmeling, S., Hirsch, M., Hogg, D. W., Lang, D., Schiminovich, D., Schölkopf, B.

arXiv:1309.0654, 2013 (techreport)

ei

link (url) [BibTex]

link (url) [BibTex]


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Detecting regulatory gene–environment interactions with unmeasured environmental factors

Fusi, N., Lippert, C., Borgwardt, K. M., Lawrence, N. D., Stegle, O.

Bioinformatics, 29(11):1382-1389, 2013 (article)

ei

DOI [BibTex]

DOI [BibTex]


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Indirect absorption spectroscopy using quantum cascade lasers: mid-infrared refractometry and photothermal spectroscopy

Pfeifer, M., Ruf, A., Fischer, P.

OPTICS EXPRESS, 21(22):25643-25654, 2013 (article)

Abstract
We record vibrational spectra with two indirect schemes that depend on the real part of the index of refraction: mid-infrared refractometry and photothermal spectroscopy. In the former, a quantum cascade laser (QCL) spot is imaged to determine the angles of total internal reflection, which yields the absorption line via a beam profile analysis. In the photothermal measurements, a tunable QCL excites vibrational resonances of a molecular monolayer, which heats the surrounding medium and changes its refractive index. This is observed with a probe laser in the visible. Sub-monolayer sensitivities are demonstrated. (C) 2013 Optical Society of America

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DOI [BibTex]


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A Comparison of Directional Distances for Hand Pose Estimation

Tzionas, D., Gall, J.

In German Conference on Pattern Recognition (GCPR), 8142, pages: 131-141, Lecture Notes in Computer Science, (Editors: Weickert, Joachim and Hein, Matthias and Schiele, Bernt), Springer, 2013 (inproceedings)

Abstract
Benchmarking methods for 3d hand tracking is still an open problem due to the difficulty of acquiring ground truth data. We introduce a new dataset and benchmarking protocol that is insensitive to the accumulative error of other protocols. To this end, we create testing frame pairs of increasing difficulty and measure the pose estimation error separately for each of them. This approach gives new insights and allows to accurately study the performance of each feature or method without employing a full tracking pipeline. Following this protocol, we evaluate various directional distances in the context of silhouette-based 3d hand tracking, expressed as special cases of a generalized Chamfer distance form. An appropriate parameter setup is proposed for each of them, and a comparative study reveals the best performing method in this context.

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pdf Supplementary Project Page link (url) DOI Project Page [BibTex]

pdf Supplementary Project Page link (url) DOI Project Page [BibTex]


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Dynamical Movement Primitives: Learning Attractor Models for Motor Behaviors

Ijspeert, A., Nakanishi, J., Pastor, P., Hoffmann, H., Schaal, S.

Neural Computation, (25):328-373, 2013, clmc (article)

Abstract
Nonlinear dynamical systems have been used in many disciplines to model complex behaviors, including biological motor control, robotics, perception, economics, traffic prediction, and neuroscience. While often the unexpected emergent behavior of nonlinear systems is the focus of investigations, it is of equal importance to create goal-directed behavior (e.g., stable locomotion from a system of coupled oscillators under perceptual guidance). Modeling goal-directed behavior with nonlinear systems is, however, rather difficult due to the parameter sensitivity of these systems, their complex phase transitions in response to subtle parameter changes, and the difficulty of analyzing and predicting their long-term behavior; intuition and time-consuming parameter tuning play a major role. This letter presents and reviews dynamical movement primitives, a line of research for modeling attractor behaviors of autonomous nonlinear dynamical systems with the help of statistical learning techniques. The essence of our approach is to start with a simple dynamical system, such as a set of linear differential equations, and transform those into a weakly nonlinear system with prescribed attractor dynamics by meansof a learnable autonomous forcing term. Both point attractors and limit cycle attractors of almost arbitrary complexity can be generated. We explain the design principle of our approach and evaluate its properties in several example applications in motor control and robotics.

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link (url) [BibTex]

link (url) [BibTex]


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On the Relations and Differences between Popper Dimension, Exclusion Dimension and VC-Dimension

Seldin, Y., Schölkopf, B.

In Empirical Inference - Festschrift in Honor of Vladimir N. Vapnik, pages: 53-57, 6, (Editors: Schölkopf, B., Luo, Z. and Vovk, V.), Springer, 2013 (inbook)

ei

[BibTex]

[BibTex]


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Modeling and Learning Complex Motor Tasks: A case study on Robot Table Tennis

Mülling, K.

Technical University Darmstadt, Germany, 2013 (phdthesis)

ei

[BibTex]

[BibTex]


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Fragmentation of Slow Wave Sleep after Onset of Complete Locked-In State

Soekadar, S. R., Born, J., Birbaumer, N., Bensch, M., Halder, S., Murguialday, A. R., Gharabaghi, A., Nijboer, F., Schölkopf, B., Martens, S.

Journal of Clinical Sleep Medicine, 9(9):951-953, 2013 (article)

ei

DOI [BibTex]

DOI [BibTex]


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Plasmonic nanohelix metamaterials with tailorable giant circular dichroism

Gibbs, J. G., Mark, A. G., Eslami, S., Fischer, P.

APPLIED PHYSICS LETTERS, 103(21), 2013, Featured cover article. (article)

Abstract
Plasmonic nanohelix arrays are shown to interact with electromagnetic fields in ways not typically seen with ordinary matter. Chiral metamaterials (CMMs) with feature sizes small with respect to the wavelength of visible light are a promising route to experimentally achieve such phenomena as negative refraction without the need for simultaneously negative e and mu. Here we not only show that giant circular dichroism in the visible is achievable with hexagonally arranged plasmonic nanohelix arrays, but that we can precisely tune the optical activity via morphology and lattice spacing. The discrete dipole approximation is implemented to support experimental data. (C) 2013 AIP Publishing LLC.

Featured cover article.

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DOI [BibTex]

DOI [BibTex]


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Automatic Malaria Diagnosis system

Mehrjou, A., Abbasian, T., Izadi, M.

In First RSI/ISM International Conference on Robotics and Mechatronics (ICRoM), pages: 205-211, 2013 (inproceedings)

ei

DOI [BibTex]

DOI [BibTex]


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AGILITY – Dynamic Full Body Locomotion and Manipulation with Autonomous Legged Robots

Hutter, M., Bloesch, M., Buchli, J., Semini, C., Bazeille, S., Righetti, L., Bohg, J.

In 2013 IEEE International Symposium on Safety, Security, and Rescue Robotics (SSRR), pages: 1-4, IEEE, Linköping, Sweden, 2013 (inproceedings)

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Quantum cryo-sieving for hydrogen isotope separation in microporous frameworks: an experimental study on the correlation between effective quantum sieving and pore size

Oh, H., Park, K. S., Kalidindi, S. B., Fischer, R. A., Hirscher, M.

{Journal of Materials Chemistry A}, 1, pages: 3244-3248, Royal Society of Chemistry, Cambridge, UK, 2013 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Intention Inference and Decision Making with Hierarchical Gaussian Process Dynamics Models

Wang, Z.

Technical University Darmstadt, Germany, 2013 (phdthesis)

ei

[BibTex]


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Angular Motion Control Using a Closed-Loop CPG for a Water-Running Robot

Thatte, N., Khoramshahi, M., Ijspeert, A., Sitti, M.

In Dynamic Walking 2013, (EPFL-CONF-199763), 2013 (inproceedings)

pi

[BibTex]

[BibTex]


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Two-dimensional magnetic micro-module reconfigurations based on inter-modular interactions

Miyashita, S., Diller, E., Sitti, M.

The International Journal of Robotics Research, 32(5):591-613, SAGE Publications Sage UK: London, England, 2013 (article)

pi

[BibTex]

[BibTex]


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Contact compliance effects in the frictional response of bioinspired fibrillar adhesives

Piccardo, M., Chateauminois, A., Fretigny, C., Pugno, N. M., Sitti, M.

Journal of The Royal Society Interface, 10(83):20130182, The Royal Society, 2013 (article)

pi

Project Page [BibTex]

Project Page [BibTex]


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Co-chairs

VINCENT, Julian, ZHU, Di, DAI, Zhendong, CHEN, Da, JIANG, Lei, KANG, Le, REN, Luquan, XUE, Qunji, Zhao, Chunsheng, BARNES, Jon, others

2013 (article)

pi

[BibTex]

[BibTex]


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Gold nanocrystals in high-temperature superconducting films: creation of pinning patterns of choice

Katzer, C., Stahl, C., Michalowski, P., Treiber, S., Schmidl, F., Seidel, P., Albrecht, J., Schütz, G.

{New Journal of Physics}, 15(11), Institute of Physics Pub., Bristol, UK, 2013 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Theory of scattering of crystal electrons at magnons

Haag, Michael, Illg, C., Fähnle, M.

{Physical Review B}, Published by the American Physical Society through the American Institute of Physics, Woodbury, NYAmerican Institute of Physics, Woodbury, NY, 2013 (article)

mms

DOI [BibTex]

DOI [BibTex]


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The effect of magnetocrystalline anisotropy on the domain structure of patterned Fe2CrSi Heusler alloy thin films

Miyawaki, T., Foerster, M., Finizio, S., Vaz, C. A. F., Mawass, M.-A., Inagaki, K., Fukatani, N., Le Guyader, L., Nolting, F., Ueda, K., Asano, H., Kläui, M.

{Journal of Applied Physcis}, 114(7), American Institute of Physics, New York, NY, 2013 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Ion beam lithography for Fresnel zone plates in X-ray microscopy

Keskinbora, K., Grévent, C., Bechtel, M., Weigand, M., Goering, E., Nadzeyka, A., Lloyd, P., Rehbein, S., Schneider, G., Follath, R., Vila-Comamala, J., Yan, H., Schütz, G.

{Optics Express}, 21(10):11747-11756, Optical Society of America, Washington, DC, 2013 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Is the angular momentum of a ferromagnetic sample after exposure to a fs laser pulse conserved?

Fähnle, M., Haag, M., Illg, C.

{Journal of Magnetism and Magnetic Materials}, 347, pages: 45-46, North-Holland, Amsterdam, 2013 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Grain boundaries as the controlling factor for the ferromagnetic behaviour of Co-doped ZnO

Straumal, B. B., Mazilkin, A. A., Protasova, S. G., Straumal, P. B., Myatiev, A. A., Schütz, G., Goering, E. J., Tietze, T., Baretzky, B.

{Philosophical Magazine}, 93(10-12):1371-1383, 2013 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Magnetic properties of electrochemically prepared crystalline films of Prussian blue-based molecular magnets Kj CrIIk [CrIII(CN)6] l \mbox⋅ mH2O

Bhatt, P., Yusuf, S. M., Bhatt, R., Schütz, G.

{Journal of Solid State Electrochemistry}, 17, pages: 1285-1293, Springer-Verlag Germany, 2013 (article)

mms

DOI [BibTex]

DOI [BibTex]


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H2/D2 adsorption and desorption studies on carbon molecular sieves with different pore structures

Krkljus, I., Steriotis, T., Charalambopoulou, G., Gotzias, A., Hirscher, M.

{Carbon}, 57, pages: 239-247, Elsevier Science, Amsterdam [u.a.], 2013 (article)

mms

DOI [BibTex]

DOI [BibTex]


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X-ray magnetic circular dichroism strongly influenced by non-magnetic cover layers

Zafar, K., Audehm, P., Schütz, G., Goering, E., Pathak, M., Chetry, K. B., LeClair, P. R., Gupta, A.

{Journal of Electron Spectroscopy and Related Phenomena}, 191, pages: 1-6, Elsevier, Amsterdam, 2013 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Learning Objective Functions for Manipulation

Kalakrishnan, M., Pastor, P., Righetti, L., Schaal, S.

In 2013 IEEE International Conference on Robotics and Automation, IEEE, Karlsruhe, Germany, 2013 (inproceedings)

Abstract
We present an approach to learning objective functions for robotic manipulation based on inverse reinforcement learning. Our path integral inverse reinforcement learning algorithm can deal with high-dimensional continuous state-action spaces, and only requires local optimality of demonstrated trajectories. We use L 1 regularization in order to achieve feature selection, and propose an efficient algorithm to minimize the resulting convex objective function. We demonstrate our approach by applying it to two core problems in robotic manipulation. First, we learn a cost function for redundancy resolution in inverse kinematics. Second, we use our method to learn a cost function over trajectories, which is then used in optimization-based motion planning for grasping and manipulation tasks. Experimental results show that our method outperforms previous algorithms in high-dimensional settings.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Structural learning

Braun, D

Scholarpedia, 8(10):12312, October 2013 (article)

Abstract
Structural learning in motor control refers to a metalearning process whereby an agent extracts (abstract) invariants from its sensorimotor stream when experiencing a range of environments that share similar structure. Such invariants can then be exploited for faster generalization and learning-to-learn when experiencing novel, but related task environments.

ei

DOI [BibTex]

DOI [BibTex]


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Topological Control of Cell Sheet Migration by the 3D Microenvironment

Song, J., Kim, Y. T., Hazar, M., LeDuc, P. R., Davidson, L. A., Sitti, M.

Biophysical Journal, 104(2):147a, Elsevier, 2013 (article)

pi

[BibTex]

[BibTex]


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Independent control of multiple magnetic microrobots in three dimensions

Diller, E., Giltinan, J., Sitti, M.

The International Journal of Robotics Research, 32(5):614-631, SAGE Publications Sage UK: London, England, 2013 (article)

pi

[BibTex]

[BibTex]


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A hybrid topological and structural optimization method to design a 3-DOF planar motion compliant mechanism

Lum, G. Z., Teo, T. J., Yang, G., Yeo, S. H., Sitti, M.

In Advanced Intelligent Mechatronics (AIM), 2013 IEEE/ASME International Conference on, pages: 247-254, 2013 (inproceedings)

pi

[BibTex]

[BibTex]


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Modular micro-robotic assembly through magnetic actuation and thermal bonding

Diller, E., Zhang, N., Sitti, M.

Journal of Micro-Bio Robotics, 8(3-4):121-131, Springer Berlin Heidelberg, 2013 (article)

pi

[BibTex]

[BibTex]


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Behavior as broken symmetry in embodied self-organizing robots

Der, R., Martius, G.

In Advances in Artificial Life, ECAL 2013, pages: 601-608, MIT Press, 2013 (incollection)

al

[BibTex]

[BibTex]


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Information Driven Self-Organization of Complex Robotic Behaviors

Martius, G., Der, R., Ay, N.

PLoS ONE, 8(5):e63400, Public Library of Science, 2013 (article)

al

link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Light-induced microbubble poration of localized cells

Fan, Qihui, Hu, Wenqi, Ohta, Aaron T

In Engineering in Medicine and Biology Society (EMBC), 2013 35th Annual International Conference of the IEEE, pages: 4482-4485, 2013 (inproceedings)

pi

[BibTex]

[BibTex]