| 1. |
- Brisbois, J., et al.
(author)
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Flux penetration in a superconducting film partially capped with a conducting layer
- 2017
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In: Physical Review B. - 2469-9969 .- 2469-9950. ; 95:9
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Journal article (peer-reviewed)abstract
- The influence of a conducting layer on the magnetic flux penetration in a superconducting Nb film is studied by magneto-optical imaging. The metallic layer partially covering the superconductor provides an additional velocity-dependent damping mechanism for the flux motion that helps to protect the superconducting state when thermomagnetic instabilities develop. If the flux advances with a velocity slower than omega = 2/mu(0)sigma t, where sigma is the cap layer conductivity and t is its thickness, the flux penetration remains unaffected, whereas for incoming flux moving faster than w, the metallic layer becomes an active screening shield. When the metallic layer is replaced by a perfect conductor, it is expected that the flux braking effect will occur for all flux velocities. We investigate this effect by studying Nb samples with a thickness step. Some of the observed features, namely the deflection of the flux trajectories at the border of the thick center, as well as the favored flux penetration at the indentation, are reproduced by time-dependent Ginzburg-Landau simulations.
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| 2. |
- Cerbu, D., et al.
(author)
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Vortex ratchet induced by controlled edge roughness
- 2013
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In: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 15
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Journal article (peer-reviewed)abstract
- We demonstrate theoretically and experimentally the generation of rectified mean vortex displacement resulting from a controlled difference between the surface barriers at the opposite borders of a superconducting strip. Our investigation focuses on Al superconducting strips where, in one of the two sample borders, a saw tooth-like array of micro-indentations has been imprinted. The origin of the vortex ratchet effect is based on the fact that (i) the onset of vortex motion is mainly governed by the entrance/nucleation of vortices and (ii) the current lines bunching produced by the indentations facilitates the entrance/nucleation of vortices. Only for one current direction the indentations are positioned at the side of vortex entry and the onset of the resistive regime is lowered compared to the opposite current direction. This investigation points to the relevance of ubiquitous border effects typically neglected when interpreting vortex ratchet measurements on samples with arrays of local asymmetric pinning sites.
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| 3. |
- Kemerink, Martijn, et al.
(author)
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Optical properties of a tip-induced quantum dot
- 2001
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In: Applied Physics A. - : Springer Verlag (Germany). - 0947-8396 .- 1432-0630. ; 72, s. S239-S242
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Journal article (peer-reviewed)abstract
- We have performed optical spectroscopy measurements on a STM-tip-induced quantum dot in a GaAs layer. The dominant confinement in the (hole) quantum dot is found to be in the direction parallel to the tip axis. Electron confinement is achieved by a sub-surface AlGaAs barrier. Current-dependent measurements indicate that many-body interactions can cause spectral blueshifts up to 75 meV for a tunneling current of 10 nA. Consequently, a full treatment of the many-body problem is required for an accurate description of this type of system.
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| 4. |
- Werren, John H, et al.
(author)
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Functional and evolutionary insights from the genomes of three parasitoid Nasonia species.
- 2010
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 327:5963, s. 343-8
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Journal article (peer-reviewed)abstract
- We report here genome sequences and comparative analyses of three closely related parasitoid wasps: Nasonia vitripennis, N. giraulti, and N. longicornis. Parasitoids are important regulators of arthropod populations, including major agricultural pests and disease vectors, and Nasonia is an emerging genetic model, particularly for evolutionary and developmental genetics. Key findings include the identification of a functional DNA methylation tool kit; hymenopteran-specific genes including diverse venoms; lateral gene transfers among Pox viruses, Wolbachia, and Nasonia; and the rapid evolution of genes involved in nuclear-mitochondrial interactions that are implicated in speciation. Newly developed genome resources advance Nasonia for genetic research, accelerate mapping and cloning of quantitative trait loci, and will ultimately provide tools and knowledge for further increasing the utility of parasitoids as pest insect-control agents.
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| 5. |
- Berna, P., Mrabet, N., T., Van Beeumen, J., Devreese, B., Porath, J., Vijayalakshmi, M., A.
(author)
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Residue accessibility, hydrogen bonding, and molecular recognition: Metal-chelate probing of active site histidines in chymotrypsins
- 1997
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In: Biochemistry. ; 36:23, s. 6896-6905
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Journal article (peer-reviewed)
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