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2003


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Experiment with a crystal-assisted positron source using 6 and 10 GeV electrons

Artru, X., Baier, V., Beloborodov, K., Bochek, G., Bogdanov, A., Bozhenok, A., Bukin, A., Burdin, S., Chehab, R., Chevallier, M., Cizeron, R., Dauvergne, D., Dimova, T., Drozdetsky, A., Druzhinin, V., Dubrovin, M., Gatignon, L., Golubev, V., Jejcic, A., Keppler, P., Kirsch, R., Kulibaba, V., Lautesse, P., Major, J., Maslov, N., Poizat, J. C., Potylitsin, A., Remillieux, J., Serednyakov, S., Shary, V., Strakhovenko, V., Sylvia, C., Vnukov, I.

{Nuclear Instruments and Methods in Physics Research B}, 201, pages: 243-252, 2003 (article)

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[BibTex]

2003


[BibTex]


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Surface patterning of SrTiO3 by 30 keV ion irradiation

Albrecht, J., Leonhardt, S., Spolenak, R., Täffner, U., Habermeier, H. U., Schütz, G.

{Surface Science Letters}, 547, pages: L847-L852, 2003 (article)

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[BibTex]

[BibTex]


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Computational approaches to motor learning by imitation

Schaal, S., Ijspeert, A., Billard, A.

Philosophical Transaction of the Royal Society of London: Series B, Biological Sciences, 358(1431):537-547, 2003, clmc (article)

Abstract
Movement imitation requires a complex set of mechanisms that map an observed movement of a teacher onto one's own movement apparatus. Relevant problems include movement recognition, pose estimation, pose tracking, body correspondence, coordinate transformation from external to egocentric space, matching of observed against previously learned movement, resolution of redundant degrees-of-freedom that are unconstrained by the observation, suitable movement representations for imitation, modularization of motor control, etc. All of these topics by themselves are active research problems in computational and neurobiological sciences, such that their combination into a complete imitation system remains a daunting undertaking - indeed, one could argue that we need to understand the complete perception-action loop. As a strategy to untangle the complexity of imitation, this paper will examine imitation purely from a computational point of view, i.e. we will review statistical and mathematical approaches that have been suggested for tackling parts of the imitation problem, and discuss their merits, disadvantages and underlying principles. Given the focus on action recognition of other contributions in this special issue, this paper will primarily emphasize the motor side of imitation, assuming that a perceptual system has already identified important features of a demonstrated movement and created their corresponding spatial information. Based on the formalization of motor control in terms of control policies and their associated performance criteria, useful taxonomies of imitation learning can be generated that clarify different approaches and future research directions.

am

link (url) [BibTex]

link (url) [BibTex]


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Efficient charge recovery method for driving piezoelectric actuators with quasi-square waves

Campolo, D., Sitti, M., Fearing, R. S.

IEEE transactions on ultrasonics, ferroelectrics, and frequency control, 50(3):237-244, IEEE, 2003 (article)

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[BibTex]

[BibTex]


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Magnetization reversal study of CoCrPt alloy thin films on a nanogranular-length scale using magnetic transmission soft x-ray microscopy

Im, M. Y., Fischer, P., Eimüller, T., Denbeaux, G., Shin, S. C.

{Applied Physics Letters}, 83(22):4589-4591, 2003 (article)

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[BibTex]

[BibTex]


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Temperature-dependent pinning of vortices in low-angle grain boundaries in YBa2Cu3O7-δ

Albrecht, J.

{Physical Review B}, 68, 2003 (article)

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[BibTex]


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Magnetic soft X-ray transmission microscopy

Fischer, P.

{Current Opinion in Solid State \& Materials Science}, 7(2):173-179, 2003 (article)

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[BibTex]

[BibTex]


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The magnetic transmission X-ray microscopy project at BESSY II

Eimüller, T., Niemann, B., Guttmann, P., Fischer, P., Englisch, U., Vatter, R., Wolter, C., Seiffert, S., Schmahl, G., Schütz, G.

{Journal de Physique IV}, 104, pages: 91-94, 2003 (article)

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[BibTex]

[BibTex]


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Ab-initio statistical mechanics for ordered compounds: single-defect theory vs. cluster-expansion techniques

Drautz, R., Schultz, I., Lechermann, F., Fähnle, M.

{Physica Status Solidi B}, 240(1):37-44, 2003 (article)

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[BibTex]

[BibTex]


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Magnetic imaging with soft x-ray microscopies

Fischer, P., Denbeaux, G., Stoll, H., Puzic, A., Raabe, J., Nolting, F., Eimüller, T., Schütz, G.

{Journal de Physique IV}, 104, pages: 471-476, 2003 (article)

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[BibTex]

[BibTex]


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Hydrogen storage in carbon nanotubes

Hirscher, M., Becher, M.

{Journal of Nanoscience and Nanotechnology}, 3(1/2):3-17, 2003 (article)

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[BibTex]

[BibTex]


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Strong influence on the electronic structure of Pt adatoms and clusters on graphite

Fauth, K., He\ssler, M., Batchelor, D., Schütz, G.

{Surface Science}, 529(3):397-402, 2003 (article)

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[BibTex]

[BibTex]


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NMR studies of hydrogen diffusion in the dihydrides of hafnium

Gottwald, J., Majer, G., Peterson, D. T., Barnes, R. G.

{Journal of Alloys and Compounds}, 356-357, pages: 274-278, 2003 (article)

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[BibTex]

[BibTex]


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The +/-45 degrees correlation interferometer as a means to measure phase noise of parametric origin

Rubiola, E., Giordano, V., Stoll, H.

{IEEE Transactions on Instrumentation and Measurement}, 52, pages: 182-188, 2003 (article)

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[BibTex]

[BibTex]


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Piezoelectrically actuated four-bar mechanism with two flexible links for micromechanical flying insect thorax

Sitti, M.

IEEE/ASME transactions on mechatronics, 8(1):26-36, IEEE, 2003 (article)

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[BibTex]


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Slow removal of vacancies in B2-Ni52Al48 upon long-term low-temperature annealing

Zhang, X. Y., Sprengel, W., Reichle, K. J., Blaurock, K., Henes, R., Schaefer, H. E.

{Physical Review B}, 68(22), 2003 (article)

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[BibTex]

[BibTex]


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Magnetic domain structure in SmCo 2 : 17 permanent magnets

Zhang, Y., Tang, W., Hadjipanayis, G. C., Chen, C. H., Goll, D., Kronmüller, H.

{IEEE Transactions on Magnetics}, 39(5):2905-2907, 2003 (article)

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[BibTex]

[BibTex]


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Energy loss and charge state dependency of swift Nq+ ions scattered off a Pt(110)(1 x 2) surface

Robin, A., Hatke, N., Jensen, J., Plachke, D., Carstanjen, H. D., Heiland, W.

{Nuclear Instruments \& Methods in Physics Research B-Beam Interactions with Materials and Atoms}, 209, pages: 259-264, 2003 (article)

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[BibTex]

[BibTex]


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Preparation and properties of [NdFeBx/Nbz]n multi-layer films

Tsai, J. L., Chin, T. S., Yao, Y. D., Melsheimer, A., Fischer, S. F., Dragon, T., Kelsch, M., Kronmüller, H.

{Physica B-Condensed Matter}, 327(2-4):283-286, 2003 (article)

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[BibTex]

[BibTex]


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Multilayered magnetic nanostrips studied by transmission X-ray microscopy

Eimüller, T., Fischer, P., Guttmann, P., Denbeaux, G., Scholz, M., Köhler, M., Schmahl, G., Bayreuther, G., Schütz, G.

{Journal de Physique IV}, 104, pages: 483-486, 2003 (article)

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[BibTex]

[BibTex]


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Imaging magnetic domain structures with soft X-ray microscopy

Fischer, P., Eimüller, T., Schütz, G., Denbeaux, G.

{Structural Chemistry}, 14(1):39-47, 2003 (article)

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[BibTex]

[BibTex]


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Hydrogen solubility and diffusivity in amorphous La14Ni86 films

Cuevas, F., Hirscher, M.

{Acta Materialia}, 51, pages: 701-712, 2003 (article)

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[BibTex]

[BibTex]


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Hydrogen interaction with carbon nanostructures - current situation and future prospects

Orimo, S., Züttel, A., Schlapbach, L., Majer, G., Fukunaga, T., Fujii, H.

{Journal of Alloys and Compounds}, 356-357, pages: 716-719, 2003 (article)

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[BibTex]

[BibTex]


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Desorption of hydrogen from blowing agents used for foaming metals

von Zeppelin, F., Hirscher, M., Stanzick, H., Banhart, J.

{Composites Science and Technology}, 63, pages: 2293-2300, 2003 (article)

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[BibTex]

[BibTex]


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Entropic wetting of a colloidal rod-sphere mixture

Roth, R., Brader, J. M., Schmidt, M.

{Europhysics Letters}, 63(4):549-555, 2003 (article)

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[BibTex]

[BibTex]

2001


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Regularized principal manifolds

Smola, A., Mika, S., Schölkopf, B., Williamson, R.

Journal of Machine Learning Research, 1, pages: 179-209, June 2001 (article)

Abstract
Many settings of unsupervised learning can be viewed as quantization problems - the minimization of the expected quantization error subject to some restrictions. This allows the use of tools such as regularization from the theory of (supervised) risk minimization for unsupervised learning. This setting turns out to be closely related to principal curves, the generative topographic map, and robust coding. We explore this connection in two ways: (1) we propose an algorithm for finding principal manifolds that can be regularized in a variety of ways; and (2) we derive uniform convergence bounds and hence bounds on the learning rates of the algorithm. In particular, we give bounds on the covering numbers which allows us to obtain nearly optimal learning rates for certain types of regularization operators. Experimental results demonstrate the feasibility of the approach.

ei

PDF [BibTex]

2001


PDF [BibTex]


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The psychometric function: II. Bootstrap-based confidence intervals and sampling

Wichmann, F., Hill, N.

Perception and Psychophysics, 63 (8), pages: 1314-1329, 2001 (article)

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PDF [BibTex]

PDF [BibTex]


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The psychometric function: I. Fitting, sampling and goodness-of-fit

Wichmann, F., Hill, N.

Perception and Psychophysics, 63 (8), pages: 1293-1313, 2001 (article)

Abstract
The psychometric function relates an observer'sperformance to an independent variable, usually some physical quantity of a stimulus in a psychophysical task. This paper, together with its companion paper (Wichmann & Hill, 2001), describes an integrated approach to (1) fitting psychometric functions, (2) assessing the goodness of fit, and (3) providing confidence intervals for the function'sparameters and other estimates derived from them, for the purposes of hypothesis testing. The present paper deals with the first two topics, describing a constrained maximum-likelihood method of parameter estimation and developing several goodness-of-fit tests. Using Monte Carlo simulations, we deal with two specific difficulties that arise when fitting functions to psychophysical data. First, we note that human observers are prone to stimulus-independent errors (or lapses ). We show that failure to account for this can lead to serious biases in estimates of the psychometric function'sparameters and illustrate how the problem may be overcome. Second, we note that psychophysical data sets are usually rather small by the standards required by most of the commonly applied statistical tests. We demonstrate the potential errors of applying traditional X^2 methods to psychophysical data and advocate use of Monte Carlo resampling techniques that do not rely on asymptotic theory. We have made available the software to implement our methods

ei

PDF [BibTex]

PDF [BibTex]


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Markovian domain fingerprinting: statistical segmentation of protein sequences

Bejerano, G., Seldin, Y., Margalit, H., Tishby, N.

Bioinformatics, 17(10):927-934, 2001 (article)

ei

PDF Web [BibTex]

PDF Web [BibTex]


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Isotropic second-order nonlinear optical susceptibilities

Fischer, P., Buckingham, A., Albrecht, A.

PHYSICAL REVIEW A, 64(5), 2001 (article)

Abstract
The second-order nonlinear optical susceptibility, in the electric dipole approximation, is only nonvanishing for materials that are noncentrosymmetric. Should the medium be isotropic, then only a chiral system. such as an optically active liquid, satisfies this symmetry requirement. We derive the quantum-mechanical form of the isotropic component of the sum- and difference-frequency susceptibility and discuss its unusual spectral properties. We show that any coherent second-order nonlinear optical process in a system of randomly oriented molecules requires the medium to be chiral. and the incident frequencies to be different and nonzero. Furthermore, a minimum of two nondegenerate excited molecular states are needed for the isotropic part of the susceptibility to be nonvanishing. The rotationally invariant susceptibility is zero in the static field limit and shows exceptionally sensitive resonance and dephasing effects that are particular to chiral centers.

pf

DOI [BibTex]

DOI [BibTex]


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Reply to “Comment on ‘Phenomenological damping in optical response tensors’”

Buckingham, A., Fischer, P.

PHYSICAL REVIEW A, 63(4), 2001 (article)

Abstract
We show that damping factors must not be incorporated in the perturbation of the ground state by a static electric field. If they are included, as in the theory of Stedman et al. {[}preceding Comment. Phys. Rev. A 63, 047801 (2001)], then there would be an electric dipole in the y direction induced in a hydrogen atom in the M-s = + 1/2 state by a static electric field in the x direction. Such a dipole is excluded by symmetry.

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DOI [BibTex]


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The coercivity of the melt-spun Sm-Fe-Ga-C permanent magnets and the effect of additives (Nb, Cu and Zr)

Zhang, J. X., Kleinschroth, I., Goll, D., Cuevas, F., Kronmüller, H.

{Journal of Physics-Condensed Matter}, 13(46):10487-10496, 2001 (article)

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[BibTex]


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Hardness-depth profile of a carbon-implanted Ti-6Al-4V alloy and its relation to composition and microstructure

Kunert, M., Kienzle, O., Baretzky, B., Baker, S. P., Mittemeijer, E. J.

{Journal of Materials Research}, 16(8):2321-2335, 2001 (article)

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[BibTex]


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New Sm(Co, Fe, Cu, Zr)(z) magnets with better temperature stability

Tang, W., Zhang, Y., Goll, D., Hadjipanayis, G. C., Kronmüller, H.

{Journal of Magnetism and Magnetic Materials}, 226(Sp. Iss. SI):1365-1366, 2001 (article)

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[BibTex]


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Hydrogen in nanostructured vanadium-hydrogen systems

Orimo, S., Kimmerle, F., Majer, G.

{Physical Review B}, 63(9), 2001 (article)

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[BibTex]

[BibTex]


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Diffusion of hydrogen in heterogeneous systems

Herrmann, A., Schimmele, L., Mössinger, J., Hirscher, M., Kronmüller, H.

{Applied Physics A-Materials Science \& Processing}, 72(2):197-208, 2001 (article)

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[BibTex]


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Structural vacancies in B2-CoAl and NiAl

Meyer, B., Bester, G., Fähnle, M.

{Scripta Materialia}, 44, pages: 2485-2488, 2001 (article)

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[BibTex]

[BibTex]


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Grain boundary phase transition in the Cu-Bi system

Straumal, B. B., Prokofyev, S. I., Chang, L.-S., Sluchanko, N. E., Baretzky, B., Gust, W., Mittemeijer, E. J.

{Diffusion and Defect Forum}, 194-199, pages: 1343-1348, 2001 (article)

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[BibTex]

[BibTex]


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Carbon nanostructures: an efficient hydrogen storage medium for fuel cells

Atkinson, K., Roth, S., Hirscher, M., Grünwald, W.

{Fuel Cells Bulletin}, 4(38):9-12, 2001 (article)

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[BibTex]

[BibTex]


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Magnetic domains in nanostructured media studied with M-TXM

Fischer, P., Eimüller, T., Schütz, G., Bayreuther, G., Tsunashima, S., Tagaki, N., Denbeaux, G., Attwood, D.

{Journal of Synchrotron Radiation}, 8, pages: 325-327, 2001 (article)

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[BibTex]


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Compound formation and abrasion resistance of ion-implanted Ti6Al4V

Schmidt, H., Schminke, A., Schmiedgen, M., Baretzky, B.

{Acta Materialia}, 49, pages: 487-495, 2001 (article)

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[BibTex]

[BibTex]


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Interpretation of ab initio total energy results in a chemical language: I. Formalism and implementation into a mixed-basis pseudopotential code

Bester, G., Fähnle, M.

{Journal of Physics-Condensed Matter}, 13(50):11541-11550, 2001 (article)

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[BibTex]

[BibTex]


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Faceting of \sum3 and \sum9 grain boundaries in copper

Straumal, B. B., Polyakov, S. A., Bischoff, E., Gust, W., Mittemeijer, E. J.

{Interface Science}, 9(3-4):287-292, 2001 (article)

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[BibTex]

[BibTex]


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Generation and application of ultra-high-intensity magnetic field gradient pulses for NMR spectroscopy

Galvosas, P., Stallmach, F., Seiffert, G., Karger, J., Kaess, U., Majer, G.

{Journal of Magnetic Resonance}, 151(2):260-268, 2001 (article)

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[BibTex]

[BibTex]


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Formation and structure of highly over-stoichiometric LaNi5+x (x\textasciitilde1) alloys obtained by manifold non-equilibrium methods

Cuevas, F., Latroche, M., Hirscher, M., Percheron-Guegan, A.

{Journal of Alloys and Compounds}, 323, pages: 4-7, 2001 (article)

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[BibTex]

[BibTex]


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Hydrogen permeability measurement through Pd, Ni and Fe membranes

Yamakawa, K., Ege, M., Ludescher, B., Hirscher, M., Kronmüller, H.

{Journal of Alloys and Compounds}, 321(1):17-23, 2001 (article)

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[BibTex]

[BibTex]


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Ab-initio statistical mechanics for the phase diagram of NiAl including the effect of vacancies

Lechermann, F., Fähnle, M.

{Physica Status Solidi B-Basic Research}, 224(2):R4-R6, 2001 (article)

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[BibTex]


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Uniaxial orientational order-disorder transitions in diammine magnesium halides, Mg(ND3)2Cl2 and Mg(ND3)2Br2, investigated by neutron diffraction

Leineweber, A., Jacobs, H., Fischer, P., Böttger, G.

{Journal of Solid State Chemistry}, 156(2):487-499, 2001 (article)

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[BibTex]


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XMCD study of the Ruddlesden-Popper Phase La1.2Nd0.2Sr1.6Mn2O7

Weigand, F., Goering, E., Geissler, J., Justen, M., Dörr, K., Ruck, K., Schütz, G.

{Journal of Synchrotron Radiation}, 8, pages: 431-433, 2001 (article)

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DOI [BibTex]

DOI [BibTex]


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Nonlinear magnetoelastic effect in ultrathin epitaxial fcc Co (001) films: an ab-initio study

Komelj, M., Fähnle, M.

{Journal of Magnetism and Magnetic Materials}, 224, pages: L1-L4, 2001 (article)

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[BibTex]

[BibTex]