| 1. |
- Birney, Ewan, et al.
(författare)
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Identification and analysis of functional elements in 1% of the human genome by the ENCODE pilot project
- 2007
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Ingår i: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 447:7146, s. 799-816
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Tidskriftsartikel (refereegranskat)abstract
- We report the generation and analysis of functional data from multiple, diverse experiments performed on a targeted 1% of the human genome as part of the pilot phase of the ENCODE Project. These data have been further integrated and augmented by a number of evolutionary and computational analyses. Together, our results advance the collective knowledge about human genome function in several major areas. First, our studies provide convincing evidence that the genome is pervasively transcribed, such that the majority of its bases can be found in primary transcripts, including non-protein-coding transcripts, and those that extensively overlap one another. Second, systematic examination of transcriptional regulation has yielded new understanding about transcription start sites, including their relationship to specific regulatory sequences and features of chromatin accessibility and histone modification. Third, a more sophisticated view of chromatin structure has emerged, including its inter-relationship with DNA replication and transcriptional regulation. Finally, integration of these new sources of information, in particular with respect to mammalian evolution based on inter- and intra-species sequence comparisons, has yielded new mechanistic and evolutionary insights concerning the functional landscape of the human genome. Together, these studies are defining a path for pursuit of a more comprehensive characterization of human genome function.
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| 2. |
- Renugopalakrishnan, V, et al.
(författare)
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Nanomaterials for energy conversion applications
- 2009
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Ingår i: Nanomaterials for Energy Conversion Applications. - : American Scientific Publishers. ; , s. 155-178
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 3. |
- Lourdudoss, Sebastian, et al.
(författare)
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Heteroepitaxy and selective epitaxy for discrete and integrated devices
- 2006
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Ingår i: 2006 CONFERENCE ON OPTOELECTRONIC AND MICROELECTRONIC MATERIALS & DEVICES. - NEW YORK : IEEE. - 9781424405770 ; , s. 309-311
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Konferensbidrag (refereegranskat)abstract
- We present first results on heteroepitaxy of InP on silicon on insulator (SOI). We also demonstrate InP nanopillar fabrication by means of selective epitaxy. Selective epitaxy is also exploited to fabricate advanced photonic integrated devices for Optical Code Division Multiplex Access (OCDMA) networking applications.
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| 4. |
- Qiu, Min, et al.
(författare)
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Negative refraction in semiconductor photonic crystals
- 2005
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Ingår i: SEMICONDUCTOR AND ORGANIC OPTOELECTRONIC MATERIALS AND DEVICES. - : SPIE. ; , s. 345-352
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Konferensbidrag (refereegranskat)abstract
- The coupling efficiency between external plane waves and the Bloch waves in photonic crystals are investigated. It is found that the coupling coefficient is highly angular dependent even for an interface between air n=l and a photonic crystal with effective index -1. It is also shown that, for point imaging by a photonic crystal slab owing to the negative refraction, the influence of the surface termination to the transmission and the imaging quality is significant. Finally, we present results demonstrating experimentally negative refraction in a two-dimensional photonic crystal.
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| 5. |
- de Rossi, S., et al.
(författare)
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Longitudinal mode selection in constricted photonic crystal guides and electrically injected lasers
- 2005
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 23:3, s. 1363-1368
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Tidskriftsartikel (refereegranskat)abstract
- Locally reducing the width of a wide photonic crystal (PhC) waveguide generates a constriction which acts as an internal reflector. We have simulated and measured the spectral behavior of a wide PhC waveguide locally constricted to a narrower PhC waveguide and ended by two cleaved facets, thus generating two coupled cavities. Passive structures as well as electrically injected active structures have been investigated. The multimode behavior of wide PhC waveguides is evidenced to play a deciding role. Modal reflection and transmission at the constriction are simulated and measured on passive PhC waveguides, when varying the constrictions' hole size and length. The spectral behavior of full-PhC electrically pumped lasers including such a constriction is measured and analyzed according to the constriction geometry. Design rules are finally proposed to take advantage of this coupled-cavities behavior for high rejection and high external efficiency monomode laser operation.
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| 6. |
- Douheret, O., et al.
(författare)
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Determination of spatial resolution in atomic-force-microscopy-based electrical characterization techniques using quantum well structures
- 2005
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 23:1, s. 61-65
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Tidskriftsartikel (refereegranskat)abstract
- In this work, a procedure to determine the spatial resolution in scan ning capacitance (SCM) and scanning spreading resistance microscopy (SSRM) is proposed and demonstrated. It is based on profiling of confined carriers (in cross section) in quantum well (QW) structures consisting of QWs with different well widths and interwell spacing. Spatial resolution of sub-5 nm was observed for SSRM with commercially available diamond-coated silicon probes and sub-30 nm for SCM with IrPt5-coated probes. The influence of experimental parameters such as tip-sample bias and tip averaging on lateral resolution is discussed and appropriate measurement conditions for performing high-resolution measurements are highlighted. Finally, it is proposed that such structures can be used not only to select probes appropriate for high resolution measurements, but also in the development of new probes.
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| 7. |
- Fischer, A.M., et al.
(författare)
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Time-resolved cathodoluminescence of Mg-doped GaN
- 2008
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 93:15
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Tidskriftsartikel (refereegranskat)abstract
- The optical properties of GaN films doped with magnesium concentrations of the order of 1018 and 1019 cm-3 have been analyzed by picosecond time-resolved cathodoluminescence spectroscopy. Two luminescence bands in the vicinity of ~3.45 and ~3.27 eV are observed to increase in intensity with Mg concentration. They have been identified as related to acceptor-bound exciton and donor-acceptor pair (DAP) transitions, respectively. Time-resolved cathodoluminescence spectra, taken at low temperatures (~4 K), show that the lifetime of the DAP peak (3.27 eV) and of what appears to be its first longitudinal-optical phonon replica at ~3.19 eV decrease with increasing Mg concentration. These peaks differ in their recombination kinetics, strongly suggesting the existence of an underlying broad emission band which may be related to Mg. © 2008 American Institute of Physics.
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| 8. |
- Kamp, M., et al.
(författare)
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Photonic crystal based active optoelectronic devices
- 2006
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Ingår i: Photonic Crystals: Advances in Design, Fabrication, and Characterization. - Weinheim, FRG : Wiley-Blackwell. - 9783527602599 ; , s. 329-346
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- We have described a number of ways to integrate photonic crystals with active optoelectronic devices. PhCs can be used as mirrors in semiconductor lasers where their high reflectivity allow the fabrication of lasers with small cavity length. Lasers with a length down to 100 μm and two PhC mirrors have been demonstrated.
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| 9. |
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| 10. |
- Qiu, Min, et al.
(författare)
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Negative refraction in two-dimensional photonic crystals
- 2005
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 80:6, s. 1231-1236
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Tidskriftsartikel (refereegranskat)abstract
- We present some of our recent results for negative refraction in photonic crystals. The concept of negative refraction in photonic crystals is firstly introduced. Then, the propagation of electromagnetic waves in photonic crystals is systematically studied. By the layer Korringa-Kohn-Rostoker method, the coupling efficiency between external plane waves and the Bloch waves in photonic crystals is investigated. It is found that the coupling coefficient is highly angular dependent even for an interface between air with n=1 and a photonic crystal with effective index n(eff)=-1. It is also shown that, for point imaging by a photonic crystal slab, owing to the negative refraction, the influence of the surface termination on the transmission and the imaging quality is significant. Finally, we present results experimentally demonstrating negative refraction in a two-dimensional photonic crystal at optical communication wavelengths.
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