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2006


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The initial oxidation of magnesium: an in situ study with XPS, HERDA and ellipsometry.

Kurth, M., Graat, P. C. J., Carstanjen, H. D., Mittemeijer, E. J.

{Surface and Interface Analysis}, 38, pages: 931-940, 2006 (article)

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2006


[BibTex]


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Temperature influence of the faceting of \sum3 and \sum9 grain boundaries in Cu

Straumal, B. B., Polyakov, S. A., Mittemeijer, E. J.

{Acta Materialia}, 54, pages: 167-172, 2006 (article)

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[BibTex]

[BibTex]


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Coercivity of 2 : 17 based permanent magnets

Kronmüller, H., Goll, D.

{Journal of the Iron and Steel Research International}, 13(Suppl. 1):39-47, 2006 (article)

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[BibTex]

[BibTex]


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Hydrogen adsorption in a nickel based coordination polymer with open metal sites in the cylindrical cavities of the desolvated framework

Dietzel, P. D. C., Panella, B., Hirscher, M., Blom, R., Fjellvag, H.

{Chemical Communications}, [2006], pages: 959-961, 2006 (article)

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DOI [BibTex]

DOI [BibTex]


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Magnetic ground states and the role of vortices in ferromagnetic hollow nanospheres

Goll, D., Macke, S., Berkowitz, A., Bertram, H. N.

{Physica B: Condensed Matter}, 372(1-2):282-285, 2006 (article)

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[BibTex]

[BibTex]


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Two-dimensional vision-based autonomous microparticle manipulation using a nanoprobe

Pawashe, C., Sitti, M.

Journal of Micromechatronics, 3(3):285-306, Brill, 2006 (article)

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[BibTex]

[BibTex]


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Engineering Entrainment and Adaptation in Limit Cycle Systems – From biological inspiration to applications in robotics

Buchli, J., Righetti, L., Ijspeert, A.

Biological Cybernetics, 95(6):645-664, December 2006 (article)

Abstract
Periodic behavior is key to life and is observed in multiple instances and at multiple time scales in our metabolism, our natural environment, and our engineered environment. A natural way of modeling or generating periodic behavior is done by using oscillators, i.e., dynamical systems that exhibit limit cycle behavior. While there is extensive literature on methods to analyze such dynamical systems, much less work has been done on methods to synthesize an oscillator to exhibit some specific desired characteristics. The goal of this article is twofold: (1) to provide a framework for characterizing and designing oscillators and (2) to review how classes of well-known oscillators can be understood and related to this framework. The basis of the framework is to characterize oscillators in terms of their fundamental temporal and spatial behavior and in terms of properties that these two behaviors can be designed to exhibit. This focus on fundamental properties is important because it allows us to systematically compare a large variety of oscillators that might at first sight appear very different from each other. We identify several specifications that are useful for design, such as frequency-locking behavior, phase-locking behavior, and specific output signal shape. We also identify two classes of design methods by which these specifications can be met, namely offline methods and online methods. By relating these specifications to our framework and by presenting several examples of how oscillators have been designed in the literature, this article provides a useful methodology and toolbox for designing oscillators for a wide range of purposes. In particular, the focus on synthesis of limit cycle dynamical systems should be useful both for engineering and for computational modeling of physical or biological phenomena.

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link (url) DOI [BibTex]


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Pulsed-field-gradient NMR study of hydrogen diffusivity in random b.c.c. alloys VyTa1-y

Grinberg, F., Majer, G., Skripov, A. N.

{Journal of Alloys and Compounds}, 425(1-2):24-27, 2006 (article)

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[BibTex]

[BibTex]


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Hydrogen storage by physisorption on porous materials

Panella, B.

Universität Stuttgart, Stuttgart, 2006 (phdthesis)

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link (url) [BibTex]

link (url) [BibTex]


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Breathing Fermi surface model for noncollinear magnetization: a generalization of the Gilbert equation

Fähnle, M., Steiauf, D.

{Physical Review B}, 73, 2006 (article)

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[BibTex]


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Reconstruction of brass for tongues and shallots from baroque organs

Baretzky, B., Friesel, M., Petelin, A., Shotanov, A., Straumal, B.

{Defect and Diffusion Forum}, 258-260, pages: 397-402, 2006 (article)

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DOI [BibTex]

DOI [BibTex]


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Softening of nanostructured Al-Zn and Al-Mg alloys after severe plastic deformation

Mazilkin, A.A., Straumal, B.B., Rabkin, E., Baretzky, B., Enders, S., Protasova, S.G., Kogtenkova, O.A., Valiev, R.Z.

{Acta Materialia}, 54, pages: 3933-3939, 2006 (article)

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[BibTex]

[BibTex]


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Theory of magnetic x-ray reflectometry on the Co2Pt7 multilayer system

Martosiswoyo, L.

Universität Stuttgart, Stuttgart, 2006 (mastersthesis)

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[BibTex]

[BibTex]


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Comment on "Spin and orbital magnetic moments of Fe3O4

Goering, E., Lafkioti, M., Gold, S.

{Physical Review Letters}, 96(3), 2006 (article)

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[BibTex]

[BibTex]


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Effect of magnetic interaction on thermally activated reversal in a magnet with a distribution of energy barriers

Zhang, H. W., Zhang, S., Sun, J. R., Shen, B. G., Goll, D., Kronmüller, H.

{Journal of the Iron and Steel Research International}, 13(Suppl. 1):60-66, 2006 (article)

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[BibTex]

[BibTex]


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A biomimetic climbing robot based on the gecko

Menon, C., Sitti, M.

Journal of Bionic Engineering, 3(3):115-125, 2006 (article)

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[BibTex]

[BibTex]


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Proximal probes based nanorobotic drawing of polymer micro/nanofibers

Nain, A. S., Amon, C., Sitti, M.

IEEE transactions on nanotechnology, 5(5):499-510, IEEE, 2006 (article)

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[BibTex]

[BibTex]


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Rocking Stamper and Jumping Snake from a Dynamical System Approach to Artificial Life

Der, R., Hesse, F., Martius, G.

Adaptive Behavior, 14(2):105-115, 2006 (article)

Abstract
Dynamical systems offer intriguing possibilities as a substrate for the generation of behavior because of their rich behavioral complexity. However this complexity together with the largely covert relation between the parameters and the behavior of the agent is also the main hindrance in the goal-oriented design of a behavior system. This paper presents a general approach to the self-regulation of dynamical systems so that the design problem is circumvented. We consider the controller (a neural net work) as the mediator for changes in the sensor values over time and define a dynamics for the parameters of the controller by maximizing the dynamical complexity of the sensorimotor loop under the condition that the consequences of the actions taken are still predictable. This very general principle is given a concrete mathematical formulation and is implemented in an extremely robust and versatile algorithm for the parameter dynamics of the controller. We consider two different applications, a mechanical device called the rocking stamper and the ODE simulations of a "snake" with five degrees of freedom. In these and many other examples studied we observed various behavior modes of high dynamical complexity.

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DOI [BibTex]

DOI [BibTex]


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Magnetic vortex core reversal by excitation with short bursts of an alternating field

Van Waeyenberge, B., Puzic, A., Stoll, H., Chou, K. W., Tyliszczak, T., Hertel, R., Fähnle, M., Bruckl, H., Rott, K., Reiss, G., Neudecker, I., Weiss, D., Back, C. H., Schütz, G.

{Nature}, 444(7118):461-464, 2006 (article)

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[BibTex]

[BibTex]


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Structure and magnetism in bcc-based iron-cobalt alloys

Diaz-Ortiz, A., Drautz, R., Fähnle, M., Dosch, H., Sanchez, J. M.

{Physical Review B}, 73, 2006 (article)

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[BibTex]

[BibTex]


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Role of nonequilibrium conduction electrons on the magnetization dynamics of ferromagnets in the s-d model

Fähnle, M., Singer, R., Steiauf, D., Antropov, V. P.

{Physical Review B}, 73, 2006 (article)

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[BibTex]

[BibTex]


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Hydrogen adsorption in metal-organic frameworks: Cu-MOFs and Zn-MOFs compared

Panella, B., Hirscher, M., Pütter, H., Müller, U.

{Advanced Functional Materials}, 16, pages: 520-524, 2006 (article)

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[BibTex]

[BibTex]


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Hardness of nanostructured Al-Zn, Al-Mg and Al-Zn-Mg alloys obtained by high-pressure torsion

Mazilkin, A.A., Baretzky, B., Enders, S., Kogtenkova, O.A., Straumal, B.B., Rabkin, E., Valiev, R.Z.

{Defect and Diffusion Forum}, 249, pages: 155-160, 2006 (article)

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[BibTex]

[BibTex]


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Magnetischer zirkularer Röntgendichroismus an Übergangsmetalloxiden

Lafkioti, M.

Universität Stuttgart, Stuttgart, 2006 (mastersthesis)

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[BibTex]

[BibTex]


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Contributions to the theory of x-ray magnetic dichroism

Dörfler, F.

Universität Stuttgart, Stuttgart, 2006 (mastersthesis)

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[BibTex]

[BibTex]

2000


Phenomenological damping in optical response tensors
Phenomenological damping in optical response tensors

Buckingham, A., Fischer, P.

PHYSICAL REVIEW A, 61(3), 2000 (article)

Abstract
Although perturbation theory applied to the optical response of a molecule or material system is only strictly valid far from resonances, it is often applied to ``near-resonance{''} conditions by means of complex energies incorporating damping. Inconsistent signs of the damping in optical response tensors have appeared in the recent literature, as have errors in the treatment of the perturbation by a static held. The ``equal-sign{''} convention used in a recent publication yields an unphysical material response, and Koroteev's intimation that linear electro-optical circular dichroism may exist in an optically active liquid under resonance conditions is also flawed. We show that the isotropic part of the Pockels tensor vanishes.

pf

DOI [BibTex]

2000


DOI [BibTex]


Ab initio investigation of the sum-frequency hyperpolarizability of small chiral molecules
Ab initio investigation of the sum-frequency hyperpolarizability of small chiral molecules

Champagne, B., Fischer, P., Buckingham, A.

CHEMICAL PHYSICS LETTERS, 331(1):83-88, 2000 (article)

Abstract
Using a sum-over-states procedure based on configuration interaction singles /6-311++G{*}{*}, we have computed the sum-frequency hyperpolarizability beta (ijk)(-3 omega; 2 omega, omega) Of two small chiral molecules, R-monofluoro-oxirane and R-(+)-propylene oxide. Excitation energies were scaled to fit experimental UV-absorption data and checked with ab initio values from time-dependent density functional theory. The isotropic part of the computed hyperpolarizabilities, beta(-3 omega; 2 omega, omega), is much smaller than that reported previously from sum-frequency generation experiments on aqueous solutions of arabinose. Comparison is made with a single-centre chiral model. (C) 2000 Elsevier Science B.V. All rights reserved.

pf

DOI [BibTex]

DOI [BibTex]


Three-wave mixing in chiral liquids
Three-wave mixing in chiral liquids

Fischer, P., Wiersma, D., Righini, R., Champagne, B., Buckingham, A.

PHYSICAL REVIEW LETTERS, 85(20):4253-4256, 2000 (article)

Abstract
Second-order nonlinear optical frequency conversion in isotropic systems is only dipole allowed for sum- and difference-frequency generation in chiral media. We develop a single-center chiral model of the three-wave mixing (sum:frequency generation) nonlinearity and estimate its magnitude. We also report results from ab initio calculations and from three- and four-wave mixing experiments in support of the theoretical estimates. We show that the second-order susceptibility in chiral liquids is much smaller than previously thought.

pf

DOI [BibTex]

DOI [BibTex]


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Two-dimensional fine particle positioning under an optical microscope using a piezoresistive cantilever as a manipulator

Sitti, M., Hashimoto, H.

journal of Micromechatronics, 1(1):25-48, Brill, 2000 (article)

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[BibTex]


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A brachiating robot controller

Nakanishi, J., Fukuda, T., Koditschek, D. E.

IEEE Transactions on Robotics and Automation, 16(2):109-123, 2000, clmc (article)

Abstract
We report on our empirical studies of a new controller for a two-link brachiating robot. Motivated by the pendulum-like motion of an apeâ??s brachiation, we encode this task as the output of a â??target dynamical system.â? Numerical simulations indicate that the resulting controller solves a number of brachiation problems that we term the â??ladder,â? â??swing-up,â? and â??ropeâ? problems. Preliminary analysis provides some explanation for this success. The proposed controller is implemented on a physical system in our laboratory. The robot achieves behaviors including â??swing locomotionâ? and â??swing upâ? and is capable of continuous locomotion over several rungs of a ladder. We discuss a number of formal questions whose answers will be required to gain a full understanding of the strengths and weaknesses of this approach.

am

link (url) [BibTex]

link (url) [BibTex]


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Diffusion von Wasserstoff in Lavesphasen / Diffusion von Wasserstoff in heterogenen Systemen.

Herrmann, A.

Universität Stuttgart, Stuttgart, 2000 (phdthesis)

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[BibTex]

[BibTex]


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Anisotropic flux pinning in thin YBCO-films by substrate modifications

Leonhardt, S., Warthmann, R., Albrecht, J., Jooss, C., Kronmüller, H., Haage, T., Zegenhagen, J., Habermeier, H.-U.

{Physica C}, 332, pages: 214-218, 2000 (article)

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[BibTex]

[BibTex]


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A review of the magnetic relaxation and its application to the study of atomic defects in α-iron and its diuluted alloys

Blythe, H. J., Kronmüller, H., Seeger, A., Walz, F.

{Physica Status Solidi (A)}, 181, pages: 233-345, 2000 (article)

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[BibTex]

[BibTex]


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Magnetic properties of Sm2Co17-xGax (x \textequals 0-7) compounds

Liang, B., Kleinschroth, I., Shen, B. G., Kronmüller, H.

{Journal of Applied Physics}, 87, pages: 5314-5316, 2000 (article)

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[BibTex]

[BibTex]


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Computational micromagnetism of magnetic structures and magnetization processes in small particles

Kronmüller, H., Hertel, R.

{Journal of Magnetism and Magnetic Materials}, 215-216, pages: 11-17, 2000 (article)

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[BibTex]

[BibTex]


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Interface-structure studies by atomic-resolution electron microscopy, order-disorder phenomena, and atomic diffusion in gas-phase-synthesized nanocrystalline solids

Schaefer, H.-E., Reimann, K., Straub, W., Phillipp, F., Tanimoto, H., Brossmann, U., Würschum, R.

{Materials Science and Engineering A}, 286, pages: 24-33, 2000 (article)

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[BibTex]

[BibTex]


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High-performance permanent magnets

Goll, D., Kronmüller, H.

{Naturwissenschaften}, 87, pages: 423-438, 2000 (article)

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[BibTex]

[BibTex]


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Nonlinear magnetoelastic coupling coefficients from simultaneous measurements of magnetostrictive stress and anisotropy in epitaxial magnetic films

Fähnle, M., Komelj, M.

{Journal of Applied Physics}, 88, pages: 2781-2786, 2000 (article)

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[BibTex]


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Reconstruction of the Mo(100) surface: a tight-binding study

Haas, H., Wang, C. Z., Ho, K. M., Fähnle, M., Elsässer, C.

{Surface Science}, 457, pages: L397-L403, 2000 (article)

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[BibTex]

[BibTex]


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The strain-softening phenomenon of icosahedral Al-Pd-Mn single quasicrystals

Brunner, D., Plachke, D., Carstanjen, H. D.

{Materials Science and Engineering A}, 294-296, pages: 773-776, 2000 (article)

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[BibTex]

[BibTex]


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Corrosion behaviour of the protective and decorative TiN coatings on large area steel strips

Vershinin, N., Filonov, K., Straumal, B., Gust, W., Wiener, I., Rabkin, E., Kazakevich, A.

{Surface and Coatings Technology}, 125, pages: 229-232, 2000 (article)

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[BibTex]

[BibTex]


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Investigation of Virtual Reality Interface for AFM-based Nano Manipulation

Horiguchi, S., Sitti, M., Hashimoto, H.

IEEJ Transactions on Electronics, Information and Systems, 120(12):1948-1956, The Institute of Electrical Engineers of Japan, 2000 (article)

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[BibTex]

[BibTex]


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Interaction of rhythmic and discrete pattern generators in single joint movements

Sternad, D., Dean, W. J., Schaal, S.

Human Movement Science, 19(4):627-665, 2000, clmc (article)

Abstract
The study investigates a single-joint movement task that combines a translatory and cyclic component with the objective to investigate the interaction of discrete and rhythmic movement elements. Participants performed an elbow movement in the horizontal plane, oscillating at a prescribed frequency around one target and shifting to a second target upon a trigger signal, without stopping the oscillation. Analyses focused on extracting the mutual influences of the rhythmic and the discrete component of the task. Major findings are: (1) The onset of the discrete movement was confined to a limited phase window in the rhythmic cycle. (2) Its duration was influenced by the period of oscillation. (3) The rhythmic oscillation was "perturbed" by the discrete movement as indicated by phase resetting. On the basis of these results we propose a model for the coordination of discrete and rhythmic actions (K. Matsuoka, Sustained oscillations generated by mutually inhibiting neurons with adaptations, Biological Cybernetics 52 (1985) 367-376; Mechanisms of frequency and pattern control in the neural rhythm generators, Biological Cybernetics 56 (1987) 345-353). For rhythmic movements an oscillatory pattern generator is developed following models of half-center oscillations (D. Bullock, S. Grossberg, The VITE model: a neural command circuit for generating arm and articulated trajectories, in: J.A.S. Kelso, A.J. Mandel, M. F. Shlesinger (Eds.), Dynamic Patterns in Complex Systems. World Scientific. Singapore. 1988. pp. 305-326). For discrete movements a point attractor dynamics is developed close to the VITE model For each joint degree of freedom both pattern generators co-exist but exert mutual inhibition onto each other. The suggested modeling framework provides a unified account for both discrete and rhythmic movements on the basis of neuronal circuitry. Simulation results demonstrated that the effects observed in human performance can be replicated using the two pattern generators with a mutually inhibiting coupling.

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link (url) [BibTex]

link (url) [BibTex]


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Influence of substrate irradiation on critical density and microstructure in YBCO thin films

Leonhardt, S., Albrecht, J., Warthmann, R., Habermeier, H.-U., Kronmüller, H.

{Physica C}, 341-348, pages: 1979-1980, 2000 (article)

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[BibTex]

[BibTex]


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Channeling of high-energy particles in bent crystals - experiments at the CERN SPS

Baurichter, A., Biino, C., Clement, M., Doble, N., Elsener, K., Fidecaro, G., Freund, A., Gatignon, L., Grafström, P., Gyr, M., Hage-Ali, M., Herr, W., Keppler, P., Kirsebom, K., Klem, J., Major, J., Medenwaldt, R., Mikkelsen, U., Moller, S. P., Siffert, P., Uggerhoj, E., Vilakazi, Z. Z., Weisse, E.

{Nuclear Instruments and Methods in Physics Research B}, 164-165, pages: 27-43, 2000 (article)

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[BibTex]

[BibTex]


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Magnetoelastic effects in ultrathin epitaxial Ni films: An ab-initio study

Komelj, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 222, pages: L 245-L 250, 2000 (article)

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[BibTex]

[BibTex]


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Evidence for near-grain boundary lattice rotations in an Fe(Si) alloy.

Rabkin, E., Semenov, V., Bischoff, E.

{Zeitschrift f\"ur Metallkunde}, 91, pages: 165-170, 2000 (article)

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[BibTex]

[BibTex]


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Electron focusing in metals and semimetals

Heil, J., Böhm, A., Gröger, A., Primke, M., Wyder, P., Keppler, P., Major, J., Bender, H., Schönherr, E., Wendel, H., Wolf, B., Würz, U., Grill, W., Herrenberger, S., Knauth, S., Lenzner, J.

{Physics Reports}, 323, pages: 387-455, 2000 (article)

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[BibTex]

[BibTex]