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2004


On the variability of manual spike sorting
On the variability of manual spike sorting

Wood, F., Black, M. J., Vargas-Irwin, C., Fellows, M., Donoghue, J. P.

IEEE Trans. Biomedical Engineering, 51(6):912-918, June 2004 (article)

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pdf pdf from publisher [BibTex]

2004


pdf pdf from publisher [BibTex]


Modeling and decoding motor cortical activity using a switching {Kalman} filter
Modeling and decoding motor cortical activity using a switching Kalman filter

Wu, W., Black, M. J., Mumford, D., Gao, Y., Bienenstock, E., Donoghue, J. P.

IEEE Trans. Biomedical Engineering, 51(6):933-942, June 2004 (article)

Abstract
We present a switching Kalman filter model for the real-time inference of hand kinematics from a population of motor cortical neurons. Firing rates are modeled as a Gaussian mixture where the mean of each Gaussian component is a linear function of hand kinematics. A “hidden state” models the probability of each mixture component and evolves over time in a Markov chain. The model generalizes previous encoding and decoding methods, addresses the non-Gaussian nature of firing rates, and can cope with crudely sorted neural data common in on-line prosthetic applications.

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pdf pdf from publisher [BibTex]

pdf pdf from publisher [BibTex]


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Model for spreading of liquid monolayers

Popescu, M. N., Dietrich, S.

Physical Review E, 69, 2004 (article)

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[BibTex]


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Calatytic reactions with bulk-mediated excursions: Mixing fails to restore chemical equilibrium

Coppey, M., Benichou, O., Klafter, J., Moreau, M., Oshanin, G.

Physical Review E, 69, 2004 (article)

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[BibTex]

[BibTex]


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Decay of correlation functions in hard-sphere mixtures: Structural crossover

Grodon, C., Dijkstra, M., Evans, R., Roth, R.

Journal of Chemical Physics, 121(16):7869-7882, 2004 (article)

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[BibTex]

[BibTex]


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Comment on "Dynamic behavior of anisotropic nonequilibrium driving lattice gases"

Caracciolo, S., Gambassi, A., Gubinelli, M., Pelissetto, A.

Physical Review Letters, 92, 2004 (article)

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[BibTex]

[BibTex]


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Continuum mesoscale theory inspired by plasticity

Sethna, J. P., Rauscher, M., Bouchaud, J.-P.

Europhysics Letters, 65(5):665-670, 2004 (article)

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[BibTex]

[BibTex]


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Colloidal hard-rod fluids near geometrically structured substrates

Harnau, L., Penna, F., Dietrich, S.

Physical Review E, 70, 2004 (article)

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[BibTex]

[BibTex]


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E. Coli Inspired Propulsion for Swimming Microrobots

Behkam, Bahareh, Sitti, Metin

pages: 1037–1041, 2004 (article)

Abstract
Medical applications are among the most fascinating areas of microrobotics. For long, scientists have dreamed of miniature smart devices that can travel inside the human body and carry out a host of complex operations such as minimally invasive surgery (MIS), highly localized drug delivery, and screening for diseases that are in their very early stages. Still a distant dream, significant progress in micro and nanotechnology brings us closer to materializing it. For such a miniature device to be injected into the body, it has to be 800 μm or smaller in diameter. Miniature, safe and energy efficient propulsion systems hold the key to maturing this technology but they pose significant challenges. Scaling the macroscale natation mechanisms to micro/nano length scales is unfeasible. It has been estimated that a vibrating-fin driven swimming robot shorter than 6 mm can not overcome the viscous drag forces in water. In this paper, the authors propose a new type of propulsion inspired by the motility mechanism of bacteria with peritrichous flagellation, such as Escherichia coli, Salmonella typhimurium and Serratia marcescens. The perfomance of the propulsive mechanism is estimated by modeling the dynamics of the motion. The motion of the moving organelle is simulated and key parameters such as velocity, distribution of force and power requirments for different configurations of the tail are determined theoretically. In order to validate the theoretical result, a scaled up model of the swimming robot is fabricated and characterized in silicone oil using the Buckingham PI theorem for scaling. The results are compared with the theoretically computed values. These robots are intended to swim in stagnation/low velocity biofluid and reach currently inaccessible areas of the human body for disease inspection and possibly treatment. Potential target regions to use these robots include eyeball cavity, cerebrospinal fluid and the urinary system.

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link (url) DOI [BibTex]

link (url) DOI [BibTex]


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Grand canonical simulations of hard-disk systems by simulated tempering

Döge, G, Mecke, K., Moller, J, Stoyan, D, Waagepetersen, R

International Journal of Modern Physics C, 15, pages: 129-147, 2004 (article)

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[BibTex]

[BibTex]


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Characterisation of irregular spatial structures by parallel sets and integral geometric measures

Arns, C. H., Knackstedt, M. A., Mecke, K.

Colloids and Surfaces A, 24, pages: 351-372, 2004 (article)

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[BibTex]

[BibTex]


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Symplectic integration methods in molecular and spin dynamics simulations

Tsai, S. H., Krech, M., Landau, D. P.

Brazilian Journal of Physics, 34, pages: 384-391, 2004 (article)

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[BibTex]

[BibTex]


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Numerical study of the cosmological velocity field as a function of density

Dominguez, A., Melott, A. L.

Astronomy \& Astrophysics, 419(2):425-437, 2004 (article)

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[BibTex]

[BibTex]


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Morphological thermodynamics of fluids: Shape dependence of free energies

König, P.-M., Roth, R., Mecke, K. R.

Physical Review Letters, 93(16), 2004 (article)

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[BibTex]

[BibTex]


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Bulk and interfacial properties of binary hard-platelet fluids

Bier, M., Harnau, L., Dietrich, S.

Physical Review E, 69, 2004 (article)

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[BibTex]

[BibTex]


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Depletion potential in colloidal mixtures of hard spheres and platelets

Harnau, L., Dietrich, S.

Physical Review E, 69, 2004 (article)

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[BibTex]


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On the definition of a unique effective temperature for non-equilibrium critical systems.

Calabrese, P., Gambassi, A.

Journal of Statistical Mechanics: Theory and Experiment, 2004 (article)

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[BibTex]

[BibTex]


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Size selectivity in channels: Exploring the role of the protein

Gillespie, D., Roth, R.

Biophysical Journal, 86(1):131A-132A, 2004 (article)

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[BibTex]

[BibTex]


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Mikroskopische Oberflächenwellen - direkt sichtbar gemacht.

Mecke, K.

Physik Journal, 3, pages: 19-20, 2004 (article)

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[BibTex]

[BibTex]


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Dynamical density functional theory for interacting Brownian particles: stochastic or deterministic?

Archer, A. J., Rauscher, M.

Journal of Physics A: Mathematical and General, 37(40):9325-9333, 2004 (article)

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[BibTex]

[BibTex]


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Nonanalytic curvature contributions to solvation free energies: influence of drying

Evans, R., Henderson, J. R., Roth, R.

Journal of Chemical Physics, 121(23):12074-12084, 2004 (article)

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[BibTex]

[BibTex]


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Diffusion Limited Aggregation with Power-Law Pinning

Hentschel, H. G. E., Popescu, M. N., Family, F.

Physical Review E, 69, 2004 (article)

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[BibTex]

[BibTex]


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Liquid-crystalline Casimir effect in the presence of a patterned substrate

Karimi Pour Haddadan, F., Schlesener, F., Dietrich, S.

Physical Review E, 70, 2004 (article)

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[BibTex]

[BibTex]


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Self-diffusion of silicon in molybdenum disilicide

Salamon, M., Strohm, A., Voss, T., Laitinen, P., Riihimäki, I., Divinski, S., Frank, W., Räisänen, J., Mehrer, H.

Philosophical Magazine, 84, pages: 737-756, 2004 (article)

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[BibTex]

[BibTex]


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Oxygen-related muon species in crystalline silicon

Schefzik, M., Schimmele, L., Seeger, A., Herlach, D., Kormann, O., Major, J., Röck, A.

Physica B, 289-290, pages: 521-524, 2004 (article)

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[BibTex]

[BibTex]


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Critical Casimir forces for O(n) systems with long-range interaction in the spherical limit

Chamati, H., Dantchev, D. M.

Physical Review E, 70(6), 2004 (article)

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[BibTex]

[BibTex]


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Random walk generated by random permutations of \textbraceleft1, 2, 3, ..., n+1)

Oshanin, G., Voituriez, R.

Journal of Physics A, 37(24):6221-6241, 2004 (article)

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[BibTex]

[BibTex]


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Molecular motor with a built-in escapement device

Oshanin, G., Klafter, J., Urbakh, M.

Europhysics Letters, 68(1):26-32, 2004 (article)

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[BibTex]

[BibTex]


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Diffusion-limited deposition of dipolar particles

De los Santos, F., Tavares, J. M., Tasinkevych, M., Da Gama, M. M. T.

Physical Review E, 69, 2004 (article)

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[BibTex]

[BibTex]


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Anisotropic diffusion-limited aggregation

Popescu, M. N., Hentschel, H. G. E., Family, F.

Physical Review E, 69, 2004 (article)

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[BibTex]

[BibTex]


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Critical adsorption and Casimir torque in wedges and at ridges

Palágyi, G., Dietrich, S.

Physical Review E, 70, 2004 (article)

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[BibTex]

[BibTex]


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Solvation force for long-ranged wall-fluid potentials

Maciolek, A., Drzewinski, A., Bryk, P.

Journal of Chemical Physics, 120, pages: 1921-1934, 2004 (article)

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[BibTex]

[BibTex]


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Reply to the \textquotesingleComment on "Transverse fluctuations in the driven lattice gas"’

Caracciolo, S., Gambassi, A., Gubinelli, M., Pelissetto, A.

Journal of Physics A, 37, pages: 8193-8195, 2004 (article)

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[BibTex]

[BibTex]


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Finite-size scaling in the driven lattice gas

Caracciolo, S., Gambassi, A., Gubinelli, M., Pelissetto, A.

Journal of Statistical Physics, 115, pages: 281-322, 2004 (article)

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[BibTex]

[BibTex]


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A Imagem da Fisica na Literatura

Mecke, K.

Gazeta de Fisica, 27(4):4-13, 2004 (article)

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[BibTex]

[BibTex]


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Discovering optimal imitation strategies

Billard, A., Epars, Y., Calinon, S., Cheng, G., Schaal, S.

Robotics and Autonomous Systems, 47(2-3):68-77, 2004, clmc (article)

Abstract
This paper develops a general policy for learning relevant features of an imitation task. We restrict our study to imitation of manipulative tasks or of gestures. The imitation process is modeled as a hierarchical optimization system, which minimizes the discrepancy between two multi-dimensional datasets. To classify across manipulation strategies, we apply a probabilistic analysis to data in Cartesian and joint spaces. We determine a general metric that optimizes the policy of task reproduction, following strategy determination. The model successfully discovers strategies in six different imitative tasks and controls task reproduction by a full body humanoid robot.

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[BibTex]

[BibTex]


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Rhythmic movement is not discrete

Schaal, S., Sternad, D., Osu, R., Kawato, M.

Nature Neuroscience, 7(10):1137-1144, 2004, clmc (article)

Abstract
Rhythmic movements, like walking, chewing, or scratching, are phylogenetically old mo-tor behaviors found in many organisms, ranging from insects to primates. In contrast, discrete movements, like reaching, grasping, or kicking, are behaviors that have reached sophistication primarily in younger species, particularly in primates. Neurophysiological and computational research on arm motor control has focused almost exclusively on dis-crete movements, essentially assuming similar neural circuitry for rhythmic tasks. In con-trast, many behavioral studies focused on rhythmic models, subsuming discrete move-ment as a special case. Here, using a human functional neuroimaging experiment, we show that in addition to areas activated in rhythmic movement, discrete movement in-volves several higher cortical planning areas, despite both movement conditions were confined to the same single wrist joint. These results provide the first neuroscientific evi-dence that rhythmic arm movement cannot be part of a more general discrete movement system, and may require separate neurophysiological and theoretical treatment.

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link (url) [BibTex]

link (url) [BibTex]


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Learning from demonstration and adaptation of biped locomotion

Nakanishi, J., Morimoto, J., Endo, G., Cheng, G., Schaal, S., Kawato, M.

Robotics and Autonomous Systems, 47(2-3):79-91, 2004, clmc (article)

Abstract
In this paper, we introduce a framework for learning biped locomotion using dynamical movement primitives based on non-linear oscillators. Our ultimate goal is to establish a design principle of a controller in order to achieve natural human-like locomotion. We suggest dynamical movement primitives as a central pattern generator (CPG) of a biped robot, an approach we have previously proposed for learning and encoding complex human movements. Demonstrated trajectories are learned through movement primitives by locally weighted regression, and the frequency of the learned trajectories is adjusted automatically by a novel frequency adaptation algorithmbased on phase resetting and entrainment of coupled oscillators. Numerical simulations and experimental implementation on a physical robot demonstrate the effectiveness of the proposed locomotioncontroller.

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link (url) [BibTex]

link (url) [BibTex]


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Atomic force microscope probe based controlled pushing for nanotribological characterization

Sitti, M.

IEEE/ASME Transactions on mechatronics, 9(2):343-349, IEEE, 2004 (article)

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[BibTex]

[BibTex]


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Feedback error learning and nonlinear adaptive control

Nakanishi, J., Schaal, S.

Neural Networks, 17(10):1453-1465, 2004, clmc (article)

Abstract
In this paper, we present our theoretical investigations of the technique of feedback error learning (FEL) from the viewpoint of adaptive control. We first discuss the relationship between FEL and nonlinear adaptive control with adaptive feedback linearization, and show that FEL can be interpreted as a form of nonlinear adaptive control. Second, we present a Lyapunov analysis suggesting that the condition of strictly positive realness (SPR) associated with the tracking error dynamics is a sufficient condition for asymptotic stability of the closed-loop dynamics. Specifically, for a class of second order SISO systems, we show that this condition reduces to KD^2 > KP; where KP and KD are positive position and velocity feedback gains, respectively. Moreover, we provide a ÔpassivityÕ-based stability analysis which suggests that SPR of the tracking error dynamics is a necessary and sufficient condition for asymptotic hyperstability. Thus, the condition KD^2>KP mentioned above is not only a sufficient but also necessary condition to guarantee asymptotic hyperstability of FEL, i.e. the tracking error is bounded and asymptotically converges to zero. As a further point, we explore the adaptive control and FEL framework for feedforward control formulations, and derive an additional sufficient condition for asymptotic stability in the sense of Lyapunov. Finally, we present numerical simulations to illustrate the stability properties of FEL obtained from our mathematical analysis.

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link (url) [BibTex]

link (url) [BibTex]