| 1. |
- Altucci, C, et al.
(författare)
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Frequency-resolved time-gated high-order harmonics
- 1998
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 58:5, s. 3934-3941
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Tidskriftsartikel (refereegranskat)abstract
- We report measurements of high-order harmonic spectra obtained with a 800-nm 150-fs loser pulse with a time-varying degree of ellipticity. The modulation of the polarization in time is achieved by using birefringent optics and self-phase modulation in a glass plate. We can create one or two temporal gates of a few femtoseconds width, during which the polarization is linear and harmonic emission is efficient. The harmonic spectra observed experimentally demonstrate that harmonics generated with linear polarization are frequency chirped. The values measured experimentally are consistent with theoretical predictions based on the strong field approximation. [S1050-2947(98)05511-5].
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| 2. |
- Gratz, M, et al.
(författare)
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X-ray generation for medical applications from a laser-produced plasma
- 1996
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Ingår i: Applied Surface Science. - : Elsevier BV. - 1873-5584 .- 0169-4332. ; 96-8, s. 443-447
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Tidskriftsartikel (refereegranskat)abstract
- We present investigations on the generation of X-ray radiation suitable for different types of medical imaging. Pulses from a 10 Hz terawatt laser system with a duration of 150 fs are focused onto a solid high-Z material target, with focal spot intensities reaching 10(18) W/cm(2). The produced plasma emits broadband X-ray radiation with photon energies up to the MeV region. The application of this X-ray radiation offers new features for medical radiography. Our source allows magnification imaging as well as ultrashort single-shot exposures. New contrast imaging techniques making use of an enhanced characteristic line emission are investigated. The experimental set-up also allows the study of ablation phenomena from sub-picosecond laser pulses by means of particle deposition on thin glass plates. Deposition patterns were studied dependent on different plasma-generation parameters.
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| 3. |
- Kohlweyer, S, et al.
(författare)
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Harmonic generation from solid-vacuum interface irradiated at high laser intensities
- 1995
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Ingår i: Optics Communications. - 0030-4018. ; 117:5-6, s. 431-438
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Tidskriftsartikel (refereegranskat)abstract
- Observations of harmonic generation from solid Al targets irradiated at intensities of 1017 W/cm2 using a tabletop Ti:sapphire terawatt laser system are reported. For irradiances with laser light at a wavelength of [lambda] = 794nm (the fundamental frequency), harmonics up to the 7th, while for irradiances with frequency doubled laser light ([lambda] = 397) nm harmonics up to the 4th of the respective incident radiation were detected.
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| 4. |
- Tillman, C, et al.
(författare)
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Elemental biological imaging by differential absorption with a laser-produced x-ray source
- 1996
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Ingår i: Journal of the Optical Society of America B: Optical Physics. - 0740-3224. ; 13:1, s. 209-215
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the novel application of hard x rays emitted by a laser-produced plasma for differential imaging of elements. An x-ray-emitting laser-produced plasma, obtained by the focusing of radiation from a 10-Hz terawatt laser, is used for biological imaging. The x-ray source can be arranged to yield characteristic x-ray emission lines with photon energies that bridge the K absorption edge of a chosen atomic species. One can obtain element-specific radiographs by recording transillumination images for different target materials on digital image plates and by subsequently subtracting or dividing the images. Successful phantom and experimental animal imaging are performed utilizing tantalum and gadolinium as target materials for the terawatt laser and gadolinium as the imaged contrast agent.
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| 5. |
- Wise, L M, et al.
(författare)
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Vascular endothelial growth factor (VEGF)-like protein from orf virus NZ2 binds to VEGFR2 and neuropilin-1.
- 1999
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - 0027-8424 .- 1091-6490. ; 96:6
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Tidskriftsartikel (refereegranskat)abstract
- Orf virus, a member of the poxvirus family, produces a pustular dermatitis in sheep, goats, and humans. The lesions induced after infection with orf virus show extensive proliferation of vascular endothelial cells, dilation of blood vessels and dermal swelling. An explanation for the nature of these lesions may lie in the discovery that orf virus encodes an apparent homolog of the mammalian vascular endothelial growth factor (VEGF) family of molecules. These molecules mediate endothelial cell proliferation, vascular permeability, angiogenesis, and lymphangiogenesis via the endothelial cell receptors VEGFR-1 (Flt1), VEGFR-2 (KDR/Flk1), and VEGFR-3 (Flt4). The VEGF-like protein of orf virus strain NZ2 (ORFV2-VEGF) is most closely related in primary structure to VEGF. In this study we examined the biological activities and receptor specificity of the ORFV2-VEGF protein. ORFV2-VEGF was found to be a disulfide-linked homodimer with a subunit of approximately 25 kDa. ORFV2-VEGF showed mitogenic activity on bovine aortic and human microvascular endothelial cells and induced vascular permeability. ORFV2-VEGF was found to bind and induce autophosphorylation of VEGFR-2 and was unable to bind or activate VEGFR-1 and VEGFR-3, but bound the newly identified VEGF165 receptor neuropilin-1. These results indicate that, from a functional viewpoint, ORFV2-VEGF is indeed a member of the VEGF family of molecules, but is unique, however, in that it utilizes only VEGFR-2 and neuropilin-1.
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