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- Ahuja, Rajeev, et al.
(author)
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Optical properties of 4H-SiC
- 2002
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In: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 91:4, s. 2099-2103
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Journal article (peer-reviewed)abstract
- The optical band gap energy and the dielectric functions of n-type 4H-SiC have been investigated experimentally by transmission spectroscopy and spectroscopic ellipsometry and theoretically by an ab initio full-potential linear muffin-tin-orbital method. We present the real and imaginary parts of the dielectric functions, resolved into the transverse and longitudinal photon moment a, and we show that the anisotropy is small in 4H-SiC. The measurements and the calculations fall closely together in a wide range of energies.
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- Apfalter, Petra, et al.
(author)
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Multicenter comparison trial of DNA extraction methods and PCR assays for detection of Chlamydia pneumoniae in endarterectomy specimens
- 2001
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In: Journal of Clinical Microbiology. - 1098-660X. ; 39:2, s. 519-524
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Journal article (peer-reviewed)abstract
- The reported rate of detection of Chlamydia pneumoniae DNA within atherosclerotic lesions by PCR varies between 0 and 100%. In this study, identical sets of coded experimental atheroma samples (n = 15) and spiked controls (n = 5) were analyzed by 16 test methods in nine centers by means of PCR. The positive controls were correctly identified to levels of 1, 0.1, and 0.01 inclusion bodies of C. pneumoniae/ml of tissue homogenate by 16 (100%), 11 (69%), and 3 (19%) of the test methods, respectively. Three out of 16 negative controls (19%) were rated positive. Positivity rates for atheroma samples varied between 0 and 60% for the different test methods, with the maximum concordant result for positivity being only 25% for one carotid artery sample. There was no consistent pattern of positive results among the various laboratories, and there was no correlation between the detection rates and the sensitivity of the assay used.
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- Drasbek, M, et al.
(author)
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Immune response to Mycoplasma pneumoniae P1 and P116 in patients with atypical pneumonia analyzed by ELISA
- 2004
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In: BMC Microbiology. - : Springer Science and Business Media LLC. - 1471-2180. ; 4
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Journal article (peer-reviewed)abstract
- Background: Serology is often used for the diagnosis of Mycoplasma pneumoniae. It is important to identify specific antigens that can distinguish between the presence or absence of antibodies against M. pneumoniae. The two proteins, P116 and P1, are found to be immunogenic. By using these in ELISA it is possible to identify an immune response against M. pneumoniae in serum samples. Results: A recombinant protein derived from the P116 protein and one from the P1 protein were used in two ELISA tests, rP116-ELISA and rP1-ELISA. Human serum samples from patients with atypical pneumonia were tested and compared to the results of the complement fixation test. There was a good agreement between the two tests but the rP1-ELISA showed the best discrimination between positive and negative samples. Conclusion: Two ELISA tests based on recombinant proteins have been analysed and compared to the complement fixation test results. The two ELISA tests were found suitable for use in serodiagnostics of M. pneumoniae infections. The use of specific antigens eliminates the risk of cross reaction to an immune response against other bacteria.
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- Norin, Johan, et al.
(author)
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Time-frequency characterization of femtosecond extreme ultraviolet pulses.
- 2002
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In: Physical Review Letters. - 1079-7114. ; 88:19, s. 193901-193901
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Journal article (peer-reviewed)abstract
- We present energy-resolved cross-correlation measurements of an extreme ultraviolet (XUV) pulse, generated as the fifth harmonic (15.5 eV) of an intense 80 fs laser pulse centered at 400 nm. Spectrally resolving the cross-correlation signal allows us to characterize the time-dependent frequency of the XUV pulse. We find that the fifth harmonic has a small negative chirp in excess of that predicted by perturbation theory. In addition, by manipulating the chirp of the driving laser we can induce and measure a positive or a negative chirp on the XUV pulse.
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- van Praagh, Martijn, et al.
(author)
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Reconsidering landfill monitoring with the aid of multivariate data analysis
- 2004
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In: Waste Management and the Environment II. - 1853127388 ; , s. 449-458
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Conference paper (peer-reviewed)abstract
- Leachate constitutes the main potential long-term environmental risk of landfill emissions. The EU landfill directive 1999/3 I/EC requires minimum monitoring during the active landfill life and the after-care phase. Due to time and resource limitations, monitoring of leachate quality is a compromise between information density and applicability. Samples from passively collected leachate are suspect to mixing with groundwater and surface water. This is especially true for the widely used parameter conductivity. The objective of this work is to identify the extent of major external influences on conductivity monitoring data and its implications for future monitoring programs. A complete eight year conductivity monitoring data set from a municipal solid waste landfill in Southern Sweden is analysed with the help of multivariate data analysis. With the aid of a principle component analysis (PCA) the influences of surface water, groundwater and recycled leachate on the complete measurements' variability is investigated. The impact of final capping on the variability is clearly reflected. A primary model is developed for the dependence of conductivity variability on water levels' variability with the help of a canonical correlation analysis (CCA). On the one hand, the results allow identification of surplus sampling points. On the other hand, crucial sampling points are highlighted, which are intensively subject to processes other than mixing with surface water. Consequently, these results make way for tailor-made monitoring for comparable landfill situations.
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