| 1. |
- Frithz-Lindsten, Elisabet, et al.
(författare)
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Functional conservation of the effector protein translocators PopB/YopB and PopD/YopD of Pseudomonas aeruginosa and Yersinia pseudotuberculosis.
- 1998
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Ingår i: Molecular Microbiology. - : John Wiley & Sons. - 0950-382X .- 1365-2958. ; 29:5, s. 1155-1165
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Tidskriftsartikel (refereegranskat)abstract
- Virulent Yersinia species cause systemic infections in rodents, and Y. pestis is highly pathogenic for humans. Pseudomonas aeruginosa, on the other hand, is an opportunistic pathogen, which normally infects only compromised individuals. Surprisingly, these pathogens both encode highly related contact-dependent secretion systems for the targeting of toxins into eukaryotic cells. In Yersinia, YopB and YopD direct the translocation of the secreted Yop effectors across the target cell membrane. In this study, we have analysed the function of the YopB and YopD homologues, PopB and PopD, encoded by P. aeruginosa. Expression of the pcrGVHpopBD operon in defined translocation-deficient mutants (yopB/yopD) of Yersinia resulted in complete complementation of the cell contact-dependent, YopE-induced cytotoxicity of Y. pseudotuberculosis on HeLa cells. We demonstrated that the complementation fully restored the ability of Y. pseudotuberculosis to translocate the effector molecules YopE and YopH into the HeLa cells. Similar to YopB, PopB induced a lytic effect on infected erythrocytes. The lytic activity induced by PopB could be prevented if the erythrocytes were infected in the presence of sugars larger than 3 nm in diameter, indicating that PopB induced a pore of similar size compared with that induced by YopB. Our findings show that the contact-dependent toxin-targeting mechanisms of Y. pseudotuberculosis and P. aeruginosa are conserved at the molecular level and that the translocator proteins are functionally interchangeable. Based on these similarities, we suggest that the translocation of toxins such as ExoS, ExoT and ExoU by P. aeruginosa across the eukaryotic cell membrane occurs via a pore induced by PopB.
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| 2. |
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| 3. |
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| 4. |
- Nyström, Kaj, 1969-
(författare)
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An estimate of a polynomial capacity
- 1998
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Ingår i: Potential Analysis. - 0926-2601 .- 1572-929X. ; 9:3, s. 217-227
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Wikström, Conny, et al.
(författare)
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Multivariate process and quality monitoring applied to an electrolysis process. : Part I - Process supervision with multivariate control charts
- 1998
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Ingår i: Chemometrics and Intelligent Laboratory Systems. - 0169-7439. ; 42, s. 221-231
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Tidskriftsartikel (refereegranskat)abstract
- Multivariate statistical process control MSPC.is applied to an electrolysis process. The process produces extremely pure copper, and to monitor its quality the levels of eight metal impurities were recorded twice a day. These quality data are analysed adopting an 1. ‘intuitive’ univariate approach, and 2. with multivariate techniques. It is demonstrated that the univariate analysis gives confusing results with regards to outlier detection, while the multivariate approach identifies two types of outliers. Moreover, it is shown how the results from the multivariate principal component analysis PCA.method can be displayed graphically in multivariate control charts. Multivariate Shewhart, cumulative sum CUSUM.and exponentially weighted moving average EWMA.control charts are used and compared. Also, an informationally powerful control chart, the simultaneous scores monitoring and residual tracking SMART.chart, is introduced and used.
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| 6. |
- Wiberg, Karin, et al.
(författare)
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Enantioselective analysis of organochlorine pesticides in herring and seal from the Swedish marine environment
- 1998
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Ingår i: Marine Pollution Bulletin. - Oxford : Pergamon Press. - 0025-326X .- 1879-3363. ; 36:5, s. 345-353
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Tidskriftsartikel (refereegranskat)abstract
- Factors influencing the changes of enantiomeric ratios (ERs) in herring (Clupea harengus), grey seal (Halichoerus grypus), harbour seal (Phoca vitulina) and ringed seal (Phoca hispida) collected along the Swedish coastline were studied by enantioselective high-resolution gas chromatography (HRGC). Three-year-old male and female herring individuals from different sampling sites were selected, whereas seal blubber and liver samples represented different species, sexes and geographical locations. Enantioselective analysis of α-hexachlorocyclohexane (α-HCH), chlordanes and chlordane metabolites were performed. In general, herring showed similar ERs within the Baltic Sea. Results indicate that species specific differences are important factors controlling the ERs of Baltic seals. Inverse ERs in seal blubber and liver, and a low deviation from the racemic ratio of some components in the liver, indicate that not only enantioselective degradation but also stereoselectivity of other processes are responsible for the changes of ERs in biota.
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| 7. |
- Gustafsson, Jörgen, et al.
(författare)
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The influence of hyperfine structure and isotope shift on the detection of Rb by 2f-wavelength modulation diode laser absorption spectrometry : experimental verification of simulations
- 1998
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Ingår i: Spectrochimica Acta Part B - Atomic Spectroscopy. - : Elsevier. - 0584-8547 .- 1873-3565. ; 53:14, s. 1895-1905
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Tidskriftsartikel (refereegranskat)abstract
- This work presents an experimental verification of a previously developed methodology for simulation of the 2f-wavelength modulation diode laser absorption spectrometry technique (2f-WM-DLAS) when the influence of hyperfine structure, isotope shift and collisional broadening and shift of an atomic transition is taken into account [J. Gustafsson, D. Rojas and O. Axner, Spectrochim. Acta, 52B, 1937-1953 (1997)]. The pilot element in the simulations was Rb, detected at the 780 nm 5s2 S1/2 - 5p2 P3/2 transition, in low-pressure cells and atmospheric-pressure reservoirs (e.g. graphite furnaces). This experimental investigation verifies that the simulations are able to predict, with good accuracy, experimental 2f-WM signals from Rb atoms under both low-pressure, room-temperature conditions and atmospheric-pressure, high-temperature conditions. This implies that the previously published simulation methodology can be used for predicting and optimizing 2f-WM signal strengths and shapes from Rb atoms (and thereby presumably also from other atoms) under a variety of pressure and temperature conditions.
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| 8. |
- Bidleman, TF, et al.
(författare)
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Chiral pesticides as tracers of air-surface exchange
- 1998
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Ingår i: Environmental Pollution. - 0269-7491 .- 1873-6424. ; 102:1, s. 43-49
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Tidskriftsartikel (refereegranskat)abstract
- The enantiomers of chiral pesticides are selectively broken down in soil and water to yield residues and metabolites, which are non-racemic. The distinctive enantiomer signatures of residues are preserved upon volatilization, providing site-specific tracers for air-soil and air-water exchange. Applications of enantiomeric tracers include distinguishing the atmospheric transport of freshly applied pesticides from those which are 'recycled' from lakes, oceans and soil, and investigating biotic vs abiotic degradation pathways. Examples are given of using pesticide enantiomers to follow volatilization from the Great Lakes and arctic waters and as indicators of pesticide emissions from agricultural soils.
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| 9. |
- Bidleman, TF, et al.
(författare)
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Soil as a source of atmospheric heptachlor epoxide
- 1998
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 32:10, s. 1546-1548
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Tidskriftsartikel (refereegranskat)abstract
- The chiral pesticide heptachlor can undergo photolysis to yield the racemic products heptachlor-exo-epoxide (HEPX) and photoheptachlor. Heptachlor is also metabolized to nonracemic HEPX in biological systems and soils. HEPX in ambient air samples from the southern United States and Lakes Ontario and Superior was nonracemic and enriched in the (+) enantiomer. Average enantiomer ratios (ER = areas of (+)/(-) HEPX) in these locations ranged from 1.51 to 2.02, and were similar to ER values of HEPX reported for agricultural soils. Airborne heptachlor was racemic, with ERs of 0.98-1.02. These results suggest that the main source of HEPX in ambient air is not photolysis of heptachlor, hut rather metabolism of heptachlor in soils followed by volatilization of HEPX. The study exemplifies the use of chiral analysis for investigating the environmental fate of pesticides.
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| 10. |
- Olofsson, Thomas, 1968-, et al.
(författare)
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A method for predicting the annual building heating demand based on limited performance data
- 1998
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Ingår i: Energy and Buildings. - : Elsevier. - 0378-7788 .- 1872-6178. ; 28:1, s. 101-108
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present an investigation of the possibility to use a neural network combined with a quasi-physical description in order to predict the annual supplied space heating demand (P) for a number of small single family buildings located in the North of Sweden. As a quasi-physical description for P, we used measured diurnal performance data from a similar building or simulated data from a steady state energy simulation software. We show that the required supplied space heating demand may be predicted with an average accuracy of 5%. The predictions were based on access to measured diurnal data of indoor and outdoor temperatures and the supplied heating demand from a limited time period, ranging from 10 to 35 days. The prediction accuracy was found to be almost independent of what time of the year the measurements were obtained from, except for periods when the supplied heating demand was very small. For models based on measurements from May and fo some buildings from April and September, the prediction was less accurate.
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