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2011


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Magnetic vortex core reversal by excitation of spin waves

Kammerer, M., Weigand, M., Curcic, M., Noske, M., Sproll, M., Vansteenkiste, A., Van Waeyenberge, B., Stoll, H., Woltersdorf, G., Back, C. H., Schütz, G.

{Nature Communications}, 2, pages: 279-284, 2011 (article)

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DOI [BibTex]

2011


DOI [BibTex]


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Understanding haptics by evolving mechatronic systems

Loeb, G. E., Tsianos, G.A., Fishel, J.A., Wettels, N., Schaal, S.

Progress in Brain Research, 192, pages: 129, 2011 (article)

am

[BibTex]

[BibTex]


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Assembly and disassembly of magnetic mobile micro-robots towards deterministic 2-D reconfigurable micro-systems

Diller, E., Pawashe, C., Floyd, S., Sitti, M.

The International Journal of Robotics Research, 30(14):1667-1680, SAGE Publications Sage UK: London, England, 2011 (article)

pi

[BibTex]

[BibTex]


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Toward simple control for complex, autonomous robotic applications: combining discrete and rhythmic motor primitives

Degallier, S., Righetti, L., Gay, S., Ijspeert, A.

Autonomous Robots, 31(2-3):155-181, October 2011 (article)

Abstract
Vertebrates are able to quickly adapt to new environments in a very robust, seemingly effortless way. To explain both this adaptivity and robustness, a very promising perspective in neurosciences is the modular approach to movement generation: Movements results from combinations of a finite set of stable motor primitives organized at the spinal level. In this article we apply this concept of modular generation of movements to the control of robots with a high number of degrees of freedom, an issue that is challenging notably because planning complex, multidimensional trajectories in time-varying environments is a laborious and costly process. We thus propose to decrease the complexity of the planning phase through the use of a combination of discrete and rhythmic motor primitives, leading to the decoupling of the planning phase (i.e. the choice of behavior) and the actual trajectory generation. Such implementation eases the control of, and the switch between, different behaviors by reducing the dimensionality of the high-level commands. Moreover, since the motor primitives are generated by dynamical systems, the trajectories can be smoothly modulated, either by high-level commands to change the current behavior or by sensory feedback information to adapt to environmental constraints. In order to show the generality of our approach, we apply the framework to interactive drumming and infant crawling in a humanoid robot. These experiments illustrate the simplicity of the control architecture in terms of planning, the integration of different types of feedback (vision and contact) and the capacity of autonomously switching between different behaviors (crawling and simple reaching).

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Magnetism studied with circularly polarized X-rays

Schütz, G., Goering, E., Stoll, H.

{International Journal of Materials Research}, 102(7):773-783, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Coupled vortex oscillations in spatially separated permalloy squares

Vogel, A., Kamionka, T., Martens, M., Drews, A., Chou, K., Tyliszczak, T., Stoll, H., Van Waeyenberge, B., Meier, G.

{Physical Review Letters}, 106, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Contruction of basis functions with crystal symmetry for the spin-cluster expansion of the magnetic energy on the atomic scale

Dietermann, F., Singer, R., Fähnle, M.

{Journal of Mathematical Physics}, 52, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic patterning perpendicular anisotropy FePd alloy films by masked ion irradiation

Merkel, D. G., Bottyán, L., Tanczikó, F., Zolnai, Z., Nagy, N., Vértesy, G., Waizinger, J., Bommer, L.

{Journal of Applied Physics}, 109(12), 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Characterization of hydrogen/deuterium adsorption sites in nanoporous Cu-BTC by low-temperature thermal-desorption mass spectroscopy

Krkljus, I., Hirscher, M.

{Microporous and Mesoporous Materials}, 142, pages: 725-729, 2011 (article)

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DOI [BibTex]


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Stability of the current-carrying state in nonhomogeneous MgB2 films

Treiber, S., Stahl, C., Schütz, G., Albrecht, J.

{Physical Review B}, 84, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Orbital reflectometry of oxide heterostructures

Benckiser, E., Haverkort, M. W., Brück, S., Goering, E., Macke, S., Fraño, A., Yang, X., Andersen, O. K., Cristiani, G., Habermeier, H., Boris, A. V., Zegkinoglou, I., Wochner, P., Kim, H., Hinkov, V., Keimer, B.

{Nature Materials}, 10(3):189-193, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Potential explanation of charge response of magnetization in nanoporous systems

Subkow, S., Fähnle, M.

{Physical Review B}, 84, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Modeling of stochastic motion of bacteria propelled spherical microbeads

Arabagi, V., Behkam, B., Cheung, E., Sitti, M.

Journal of Applied Physics, 109(11):114702, AIP, 2011 (article)

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Project Page [BibTex]

Project Page [BibTex]


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The effect of aspect ratio on adhesion and stiffness for soft elastic fibres

Aksak, B., Hui, C., Sitti, M.

Journal of The Royal Society Interface, 8(61):1166-1175, The Royal Society, 2011 (article)

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Project Page [BibTex]

Project Page [BibTex]


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Large hidden orbital moments in magnetite

Goering, E.

{Physica Status Solidi B}, 248(10):2345-2351, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Cr magnetization reversal at the CrO2/RuO2 interface: Origin of the reduced GMR effect

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

{Physical Review B}, 84, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetocaloric effect, magnetic domain structure and spin-reorientation transitios in HoCo5 single crystals

Skokov, K. P., Pastushenkov, Y. G., Koshkid\textquotesingleko, Y. S., Schütz, G., Goll, D., Ivanova, T. I., Nikitin, S. A., Semenova, E. M., Petrenko, A. V.

{Journal of Magnetism and Magnetic Materials}, 323(5):447-450, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Elucidating gating effects for hydrogen sorption in MFU-4-type triazolate-based metal-organic frameworks featuring different pore sizes

Denysenko, D., Grzywa, M., Tonigold, M., Streppel, B., Krkljus, I., Hirscher, M., Mugnaioli, E., Kolb, U., Hanss, J., Volkmer, D.

{Chemistry - A European Journal}, 17(6):1837-1848, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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BET specific surface area and pore structure of MOFs determined by hydrogen adsorption at 20 K

Streppel, B., Hirscher, M.

{Physical Chemistry Chemical Physics}, 13(8):3220-3222, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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High contrast magnetic and nonmagnetic sample current microscopy for bulk and transparent samples using soft X-rays

Nolle, D., Weigand, M., Schütz, G., Goering, E.

{Microscopy and Microanalysis}, 17, pages: 834-842, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic vortex core reversal by rotating magnetic fields generated on micrometer length scales

Curcic, M., Stoll, H., Weigand, M., Sackmann, V., Jüllig, P., Kammerer, M., Noske, M., Sproll, M., Van Waeyenberge, B., Vansteenkiste, A., Woltersdorf, G., Tyliszczak, T., Schütz, G.

{Physica Status Solidi B}, 248(10):2317-2322, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Enhancing adhesion of biologically inspired polymer microfibers with a viscous oil coating

Cheung, E., Sitti, M.

The Journal of Adhesion, 87(6):547-557, Taylor & Francis Group, 2011 (article)

pi

Project Page [BibTex]

Project Page [BibTex]


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Formation of two amorphous phases in the Ni60Nb18Y22 alloy after high pressure torsion

Straumal, B. B., Mazilkin, A. A., Protasova, S. G., Goll, D., Baretzky, B., Bakai, A. S., Dobatkin, S. V.

{Kovove Materialy-Metallic Materials}, 49(1):17-22, 2011 (article)

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link (url) [BibTex]

link (url) [BibTex]


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Structure and properties of nanograined Fe-C alloys after severe plastic deformation

Straumal, B. B., Dobatkin, S. V., Rodin, A. O., Protasova, S. G., Mazilkin, A. A., Goll, D., Baretzky, B.

{Advanced Engineering Materials}, 13(6):463-469, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Increased flux pinning in YBa2Cu3O7-δthin-film devices through embedding of Au nano crystals

Katzer, C., Schmidt, M., Michalowski, P., Kuhwald, D., Schmidl, F., Grosse, V., Treiber, S., Stahl, C., Albrecht, J., Hübner, U., Undisz, A., Rettenmayr, M., Schütz, G., Seidel, P.

{Europhysics Letters}, 95(6), 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Signal transfer in a chain of stray-field coupled ferromagnetic squares

Vogel, A., Martens, M., Weigand, M., Meier, G.

{Applied Physics Letters}, 99, 2011 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Electron theory of magnetoelectric effects in metallic ferromagnetic nanostructures

Subkow, S., Fähnle, M.

{Physical Review B}, 84, 2011 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Magnetic antivortex-core reversal by rotating magnetic fields

Kamionka, T., Martens, M., Chou, K., Drews, A., Tyliszczak, T., Stoll, H., Van Waeyenberge, B., Meier, G.

{Physical Review B}, 83, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic properties of exchange-spring composite films

Kronmüller, H., Goll, D.

{Physica Status Solidi B}, 248(10):2361-2367, 2011 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Wetting transition of grain boundaries in the Sn-rich part of the Sn-Bi phase diagram

Yeh, C.-H., Chang, L.-S., Straumal, B. B.

{Journal of Materials Science}, 46(5):1557-1562, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Piezoelectric polymer fiber arrays for tactile sensing applications

Sümer, B., Aksak, B., Şsahin, K., Chuengsatiansup, K., Sitti, M.

Sensor Letters, 9(2):457-463, American Scientific Publishers, 2011 (article)

pi

Project Page [BibTex]

Project Page [BibTex]


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Control methodologies for a heterogeneous group of untethered magnetic micro-robots

Floyd, S., Diller, E., Pawashe, C., Sitti, M.

The International Journal of Robotics Research, 30(13):1553-1565, SAGE Publications, 2011 (article)

pi

[BibTex]

[BibTex]


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Influence of dot size and annealing on the magnetic properties of large-area L10-FePt nanopatterns

Bublat, T., Goll, D.

{Journal of Applied Physics}, 110(7), 2011 (article)

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DOI [BibTex]


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The temperature-dependent magnetization profile across an epitaxial bilayer of ferromagnetic La2/3Ca1/3MnO3 and superconducting YBa2Cu3O7-δ

Brück, S., Treiber, S., Macke, S., Audehm, P., Christiani, G., Soltan, S., Habermeier, H., Goering, E., Albrecht, J.

{New Journal of Physics}, 13(3), 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Spin interactions in bcc and fcc Fe beyond the Heisenberg model

Singer, R., Dietermann, F., Fähnle, M.

{Physical Review Letters}, 107, 2011 (article)

mms

DOI [BibTex]

DOI [BibTex]


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Route to a family of robust, non-interpenetrated metal-organic frameworks with pto-like topology

Klein, N., Senkovska, I., Baburin, I. A., Grünker, R., Stoeck, U., Schlichtenmayer, M., Streppel, B., Mueller, U., Leoni, S., Hirscher, M., Kaskel, S.

{Chemistry - A European Journal}, 17(46):13007-13016, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Initial stages of growth of iron on silicon for spin injection through Schottky barrier

Dash, S. P., Carstanjen, H. D.

{Physica Status Solidi B}, 248(10):2300-2304, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Fe3O4/ZnO: A high-quality magnetic oxide-semiconductor heterostructure by reactive deposition

Paul, M., Kufer, D., Müller, A., Brück, S., Goering, E., Kamp, M., Verbeeck, J., Tian, H., Van Tendeloo, G., Ingle, N. J. C., Sing, M., Claessen, R.

{Applied Physics Letters}, 98, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Influence of texture on the ferromagnetic properties of nanograined ZnO films

Straumal, B., Mazilkin, A., Protasova, S., Myatiev, A., Straumal, P., Goering, E., Baretzky, B.

{Physica Status Solidi B}, 248(7):1581-1586, 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Control of spin configuration in half-metallic La0.7Sr0.3MnO3 nano-structures

Rhensius, J., Vaz, C. A. F., Bisig, A., Schweitzer, S., Heidler, J., Körner, H. S., Locatelli, A., Niño, M. A., Weigand, M., Méchin, L., Gaucher, F., Goering, E., Heyderman, L. J., Kläui, M.

{Applied Physics Letters}, 99(6), 2011 (article)

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DOI [BibTex]

DOI [BibTex]


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Comparison of various sol-gel derived metal oxide layers for inverted organic solar cells

Oh, H., Krantz, J., Litzov, I., Stubhan, T., Pinna, L., Brabec, C. J.

{Solar Energy Materials \& Solar Cells}, 95(8):2194-2199, 2011 (article)

mms

DOI [BibTex]

DOI [BibTex]

2007


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Reaction graph kernels for discovering missing enzymes in the plant secondary metabolism

Saigo, H., Hattori, M., Tsuda, K.

NIPS Workshop on Machine Learning in Computational Biology, December 2007 (talk)

Abstract
Secondary metabolic pathway in plant is important for finding druggable candidate enzymes. However, there are many enzymes whose functions are still undiscovered especially in organism-specific metabolic pathways. We propose reaction graph kernels for automatically assigning the EC numbers to unknown enzymatic reactions in a metabolic network. Experiments are carried out on KEGG/REACTION database and our method successfully predicted the first three digits of the EC number with 83% accuracy.We also exhaustively predicted missing enzymatic functions in the plant secondary metabolism pathways, and evaluated our results in biochemical validity.

ei

Web [BibTex]

2007


Web [BibTex]


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Positional Oligomer Importance Matrices

Sonnenburg, S., Zien, A., Philips, P., Rätsch, G.

NIPS Workshop on Machine Learning in Computational Biology, December 2007 (talk)

Abstract
At the heart of many important bioinformatics problems, such as gene finding and function prediction, is the classification of biological sequences, above all of DNA and proteins. In many cases, the most accurate classifiers are obtained by training SVMs with complex sequence kernels, for instance for transcription starts or splice sites. However, an often criticized downside of SVMs with complex kernels is that it is very hard for humans to understand the learned decision rules and to derive biological insights from them. To close this gap, we introduce the concept of positional oligomer importance matrices (POIMs) and develop an efficient algorithm for their computation. We demonstrate how they overcome the limitations of sequence logos, and how they can be used to find relevant motifs for different biological phenomena in a straight-forward way. Note that the concept of POIMs is not limited to interpreting SVMs, but is applicable to general k−mer based scoring systems.

ei

Web [BibTex]

Web [BibTex]


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Machine Learning Algorithms for Polymorphism Detection

Schweikert, G., Zeller, G., Weigel, D., Schölkopf, B., Rätsch, G.

NIPS Workshop on Machine Learning in Computational Biology, December 2007 (talk)

ei

Web [BibTex]

Web [BibTex]


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A Tutorial on Spectral Clustering

von Luxburg, U.

Statistics and Computing, 17(4):395-416, December 2007 (article)

Abstract
In recent years, spectral clustering has become one of the most popular modern clustering algorithms. It is simple to implement, can be solved efficiently by standard linear algebra software, and very often outperforms traditional clustering algorithms such as the k-means algorithm. On the first glance spectral clustering appears slightly mysterious, and it is not obvious to see why it works at all and what it really does. The goal of this tutorial is to give some intuition on those questions. We describe different graph Laplacians and their basic properties, present the most common spectral clustering algorithms, and derive those algorithms from scratch by several different approaches. Advantages and disadvantages of the different spectral clustering algorithms are discussed.

ei

PDF PDF DOI [BibTex]

PDF PDF DOI [BibTex]


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An Automated Combination of Kernels for Predicting Protein Subcellular Localization

Zien, A., Ong, C.

NIPS Workshop on Machine Learning in Computational Biology, December 2007 (talk)

Abstract
Protein subcellular localization is a crucial ingredient to many important inferences about cellular processes, including prediction of protein function and protein interactions.We propose a new class of protein sequence kernels which considers all motifs including motifs with gaps. This class of kernels allows the inclusion of pairwise amino acid distances into their computation. We utilize an extension of the multiclass support vector machine (SVM)method which directly solves protein subcellular localization without resorting to the common approach of splitting the problem into several binary classification problems. To automatically search over families of possible amino acid motifs, we optimize over multiple kernels at the same time. We compare our automated approach to four other predictors on three different datasets, and show that we perform better than the current state of the art. Furthermore, our method provides some insights as to which features are most useful for determining subcellular localization, which are in agreement with biological reasoning.

ei

Web [BibTex]

Web [BibTex]


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A Tutorial on Kernel Methods for Categorization

Jäkel, F., Schölkopf, B., Wichmann, F.

Journal of Mathematical Psychology, 51(6):343-358, December 2007 (article)

Abstract
The abilities to learn and to categorize are fundamental for cognitive systems, be it animals or machines, and therefore have attracted attention from engineers and psychologists alike. Modern machine learning methods and psychological models of categorization are remarkably similar, partly because these two fields share a common history in artificial neural networks and reinforcement learning. However, machine learning is now an independent and mature field that has moved beyond psychologically or neurally inspired algorithms towards providing foundations for a theory of learning that is rooted in statistics and functional analysis. Much of this research is potentially interesting for psychological theories of learning and categorization but also hardly accessible for psychologists. Here, we provide a tutorial introduction to a popular class of machine learning tools, called kernel methods. These methods are closely related to perceptrons, radial-basis-function neural networks and exemplar theories of catego rization. Recent theoretical advances in machine learning are closely tied to the idea that the similarity of patterns can be encapsulated in a positive definite kernel. Such a positive definite kernel can define a reproducing kernel Hilbert space which allows one to use powerful tools from functional analysis for the analysis of learning algorithms. We give basic explanations of some key concepts—the so-called kernel trick, the representer theorem and regularization—which may open up the possibility that insights from machine learning can feed back into psychology.

ei

PDF Web DOI [BibTex]

PDF Web DOI [BibTex]


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Accurate Splice site Prediction Using Support Vector Machines

Sonnenburg, S., Schweikert, G., Philips, P., Behr, J., Rätsch, G.

BMC Bioinformatics, 8(Supplement 10):1-16, December 2007 (article)

Abstract
Background: For splice site recognition, one has to solve two classification problems: discriminating true from decoy splice sites for both acceptor and donor sites. Gene finding systems typically rely on Markov Chains to solve these tasks. Results: In this work we consider Support Vector Machines for splice site recognition. We employ the so-called weighted degree kernel which turns out well suited for this task, as we will illustrate in several experiments where we compare its prediction accuracy with that of recently proposed systems. We apply our method to the genome-wide recognition of splice sites in Caenorhabditis elegans, Drosophila melanogaster, Arabidopsis thaliana, Danio rerio, and Homo sapiens. Our performance estimates indicate that splice sites can be recognized very accurately in these genomes and that our method outperforms many other methods including Markov Chains, GeneSplicer and SpliceMachine. We provide genome-wide predictions of splice sites and a stand-alone prediction tool ready to be used for incorporation in a gene finder. Availability: Data, splits, additional information on the model selection, the whole genome predictions, as well as the stand-alone prediction tool are available for download at http:// www.fml.mpg.de/raetsch/projects/splice.

ei

PDF DOI [BibTex]

PDF DOI [BibTex]


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Challenges in Brain-Computer Interface Development: Induction, Measurement, Decoding, Integration

Hill, NJ.

Invited keynote talk at the launch of BrainGain, the Dutch BCI research consortium, November 2007 (talk)

Abstract
I‘ll present a perspective on Brain-Computer Interface development from T{\"u}bingen. Some of the benefits promised by BCI technology lie in the near foreseeable future, and some further away. Our motivation is to make BCI technology feasible for the people who could benefit from what it has to offer soon: namely, people in the "completely locked-in" state. I‘ll mention some of the challenges of working with this user group, and explain the specific directions they have motivated us to take in developing experimental methods, algorithms, and software.

ei

[BibTex]

[BibTex]