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| 2. |
- Andersson-Engels, Stefan, et al.
(författare)
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Time-resolved and Wavelength-resolved Spectroscopy In 2-photon-excited Fluorescence Microscopy
- 1994
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Ingår i: Journal of Microscopy. - 0022-2720. ; 176, s. 195-203
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Tidskriftsartikel (refereegranskat)abstract
- Two-photon excited fluorescence spectroscopy has been performed at a microscopic scale in combination with normal, white-light microscopy. This gave simultaneously a spectral resolution of 20 nm and a temporal resolution of 20 ps, from a volume element less than 5 mu m in all three dimensions. The sample was excited with the light from a continuously mode-locked Ti:sapphire laser that was focused on the sample in a fluorescence microscope. A polychromator and a streak-camera were used for detection. The method has been used on tissue, plant and paper samples. It has also been demonstrated how substances naturally occurring in the samples can be identified from their spectroscopic properties and the spatial distribution of these substances can be observed.
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| 3. |
- Da Via, C, et al.
(författare)
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Lightwave Analogue Links For LHC Detector Front-ends
- 1994
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 344:1, s. 199-211
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Tidskriftsartikel (refereegranskat)abstract
- The requirements on optical links for transferring analog and digital signals from the detector front-ends to the readout electronics at future high-luminosity colliders are reviewed. The advantages of external modulation techniques are discussed. An outline is given of the the R&D programme recently started at CERN by a collaboration involving high-energy physics institutes, optoelectronics research laboratories and industry, in order to develop electro-optic intensity modulator arrays, particularly for analogue applications, and to investigate the feasibility of volume production. The design of multichannel demonstrators in lithium niobate and III-V semiconductor technology is described. Preliminary results of the performance measurements are presented.
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| 4. |
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| 5. |
- Jansson, Stefan, 1959-, et al.
(författare)
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LIGHT-INDUCED-CHANGES OF PHOTOSYSTEM-II ACTIVITY IN DARK-GROWN SCOTS PINE-SEEDLINGS
- 1992
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Ingår i: Physiologia Plantarum. - : Wiley. - 0031-9317 .- 1399-3054. ; 84:1, s. 6-12
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Tidskriftsartikel (refereegranskat)abstract
- Both chlorophyll a and b and polypeptides of the photosynthetic apparatus are found in gymnosperm seedlings germinated and grown in absolute darkness. The photosystem II (PSII) activity is, however, limited, probably due to an inactive oxygen evolving system. In the present study dark-grown seedlings of Scots pine (Pinus sylvestris I..) were transferred to light and changes in antenna size and the activation process of PSII were investigated using fluorescence measurements and quantitative western blotting. It was found that the activation process is rapid, requires very little light and that strong light inhibits the process. It takes place without any changes in the primary reactions of PSII. Furthermore, all polypeptides except the major light-harvesting chlorophyll alb-binding protein complex of PSII (LHCII) were present in dark-grown seedlings in amounts comparable to the light treated control. The dark-grown seedlings had the same LHCII polypeptide composition as light treated seedlings, and the LHCII present seemed to be fully connected to the reaction centre. The results indicate that activation of PSII in dark-grown conifer seedlings resembles the photoactivation process of angiosperms. This implies that the fundamental processes in the assembly of the photosystem II complex is the same in all plants, but that the regulation differs between different taxa.
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| 7. |
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| 8. |
- Svanberg, Katarina, et al.
(författare)
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Photodynamic Therapy of Nonmelanoma Malignant-tumors of the Skin Using Topical Delta-amino Levulinic Acid Sensitization and Laser Irradiation
- 1994
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Ingår i: British Journal of Dermatology. - : Oxford University Press (OUP). - 1365-2133 .- 0007-0963. ; 130:6, s. 743-751
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Tidskriftsartikel (refereegranskat)abstract
- Eighty basal cell carcinomas (BCCs) in 21 patients, 10 lesions of Bowen's disease in three patients, and four lesions of cutaneous T-cell lymphoma in two patients, were treated with photodynamic laser therapy (PDT), using topical application of the haem precursor delta-amino levulinic acid (ALA). The diagnoses were confirmed histologically prior to treatment. Fifty-five of the BCCs were superficial lesions, and 25 were nodular. Of the 80 BCCs, 39 (49%) were located on the trunk, 36 (45%) on the head and neck region, four (15%) on the leg and one on the arm. The two principal locations of the 10 Bowen's disease lesions were the leg (50%) and the trunk (40%). The T-cell lymphoma lesions were located on the shoulder and on the arm. A water-in-oil based cream containing 20% ALA was applied to the lesions, with a margin of about 10-20 mm beyond the visible tumour border, 4-6 h before the laser procedure. During this period of time the highly fluorescent and photodynamically active substance protoporphyrin IX (Pp IX) is synthesized via the haem cycle. Laser-induced fluorescence (LIF) was used for real-time monitoring of the Pp IX distribution in the tumour and in the normal surrounding skin, before and after treatment in all patients. Before laser treatment the Pp-IX distribution demonstrated by LIF showed a demarcation between tumour and normal skin of about 15:1 for BCC and Bowen's disease, and 5:1 for T-cell lymphomas. Laser light from a pulsed frequency-doubled Nd:YAG laser pumping a dye laser with light emission at 630 nn was used for the therapy. The power density in the irradiation was kept below 110 mW/cm(2), in order to avoid hyperthermal effects. A total energy of 60 J/cm(2) was delivered for 10-20 min, depending on the tumour size. A complete response rate of 100% in superficial BCCs and 64% in nodular BCCs occurred after a single laser treatment, and a response rate of 100% was achieved after one additional. treatment in the nodular BCCs. in the Bowen's disease lesions a complete response of 90% was obtained with a single treatment. Two of the four T-cell lymphomas resolved completely. The follow-up time was between 6 and 14 months.
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| 9. |
- Trepte, O, et al.
(författare)
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Studies of Porphyrin-containing Specimens Using An Optical Spectrometer Connected To A Confocal Scanning Laser Microscope
- 1994
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Ingår i: Journal of Microscopy. - 0022-2720. ; 176, s. 238-244
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Tidskriftsartikel (refereegranskat)abstract
- A spectrometer has been developed for use with a confocal scanning laser microscope. With this unit, spectral information from a single point or a user-defined region within the microscope specimen can be recorded. A glass prism is used to disperse the spectral components of the recorded light over a linear CCD photodiode array with 256 elements. A regulated cooling unit keeps the detector at 277 K, thereby allowing integration times of up to 60 s. The spectral resolving power, lambda/Delta lambda, ranges from 350 at lambda = 400 nm to 100 at gamma = 700 nm. Since the entrance aperture of the spectrometer has the same size as the detector pinhole used during normal confocal scanning, the three-dimensional spatial resolution is equivalent to that of normal confocal scanning. Light from the specimen is deflected to the spectrometer by a solenoid controlled mirror, allowing fast and easy switching between normal confocal scanning and spectrometer readings. With this equipment, studies of rodent liver specimens containing porphyrins have been made. The subcellular localization is of interest for the mechanisms of photodynamic therapy (PDT) of malignant tumours. Spectroscopic detection is necessary to distinguish the porphyrin signal from other fluorescent components in the specimen. Two different substances were administered to the tissue, Photofrin, a haematoporphyrin derivative (HPD) and delta-amino levulinic acid (ALA), a precursor to protoporphyrin IX and haem in the haem cycle. Both are substances under clinical trials for PDT of malignant tumours. Following administration of these compounds to the tissue, the potent photosensitizer and fluorescent compound Photofrin, or protoporphyrin IX, respectively, is accumulated. For our study Wistar/Furth rats were injected either with Photofrin or with ALA 3-5 h before they were killed. The organs were removed directly after, and snap-frozen in carbon dioxide ice with isopentane. No further staining or fixation procedures were adopted.
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