| 1. |
- Aurora, P., et al.
(författare)
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Multiple breath inert gas washout as a measure of ventilation distribution in children with cystic fibrosis
- 2004
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Ingår i: Thorax. - : BMJ. - 0040-6376. ; 59:12, s. 1068-73
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Multiple breath inert gas washout (MBW) has been suggested as a tool for detecting early cystic fibrosis (CF) lung disease. A study was undertaken to compare the relative sensitivity of MBW and spirometry for detecting abnormal lung function in school age children with CF and to compare MBW results obtained from healthy children in the UK with those recently reported from Sweden. METHODS: Forced expiratory volume in 1 second (FEV1) and maximal expiratory flow when 25% of forced vital capacity remains to be expired (MEF25) were compared with the lung clearance index (LCI) derived from sulphur hexafluoride MBW in 22 children with CF aged 6-16 years and in 33 healthy controls. RESULTS: LCI was higher in children with CF than in healthy controls (mean difference 5.1 (95% CI of difference 4.1 to 6.1) and FEV1 and MEF25 z-scores were lower (mean difference -2.3 (95% CI -2.9 to -1.7) and -1.8 (95% CI -2.4 to -1.3), respectively; p<0.001 for all). There was a significant negative correlation between LCI and FEV1 (r2 = 0.62) and MEF25 (r2 = 0.46). However, while normal (> or =-1.96 z-scores) FEV1 and MEF25 results were seen in 11 (50%) and 12 (53%) children with CF, respectively, all but one of these children had an abnormally increased LCI. LCI was repeatable in both groups (within subject CV for three measurements 6% for CF and 5% for healthy children). In healthy subjects LCI was independent of age and virtually identical in the British and Swedish children (mean difference 0.1 (95% CI -0.1 to 0.4), p = 0.38) CONCLUSIONS: MBW is reproducible between laboratories, generates normal ranges which are constant over childhood, and is more frequently abnormal than spirometry in children with CF.
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| 2. |
- Alavi, Y., et al.
(författare)
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The dynamics of interactions between Plasmodium and the mosquito : a study of the infectivity of Plasmodium berghei and Plasmodium gallinaceum, and their transmission by Anopheles stephensi, Anopheles gambiae and Aedes aegypti
- 2003
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Ingår i: International Journal of Parasitology. - : Elsevier. - 0020-7519 .- 1879-0135. ; 33:9, s. 933-943
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Tidskriftsartikel (refereegranskat)abstract
- Knowledge of parasite–mosquito interactions is essential to develop strategies that will reduce malaria transmission through the mosquito vector. In this study we investigated the development of two model malaria parasites, Plasmodium berghei and Plasmodium gallinaceum, in three mosquito species Anopheles stephensi, Anopheles gambiae and Aedes aegypti. New methods to study gamete production in vivo in combination with GFP-expressing ookinetes were employed to measure the large losses incurred by the parasites during infection of mosquitoes. All three mosquito species transmitted P. gallinaceum; P. berghei was only transmitted by Anopheles spp. Plasmodium gallinaceum initiates gamete production with high efficiency equally in the three mosquito species. By contrast P. berghei is less efficiently activated to produce gametes, and in Ae. aegypti microgamete formation is almost totally suppressed. In all parasite/vector combinations ookinete development is inefficient, 500–100,000-fold losses were encountered. Losses during ookinete-to-oocyst transformation range from fivefold in compatible vector parasite combinations (P. berghei/An. stephensi), through >100-fold in poor vector/parasite combinations (P. gallinaceum/An. stephensi), to complete blockade (>1,500 fold) in others (P. berghei/Ae. aegypti). Plasmodium berghei ookinetes survive poorly in the bloodmeal of Ae. aegypti and are unable to invade the midgut epithelium. Cultured mature ookinetes of P. berghei injected directly into the mosquito haemocoele produced salivary gland sporozoites in An. stephensi, but not in Ae. aegypti, suggesting that further species-specific incompatibilities occur downstream of the midgut epithelium in Ae. aegypti. These results show that in these parasite–mosquito combinations the susceptibility to malarial infection is regulated at multiple steps during the development of the parasites. Understanding these at the molecular level may contribute to the development of rational strategies to reduce the vector competence of malarial vectors.
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| 3. |
- Bryant, C.H., et al.
(författare)
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Combining Inductive Logic Programming, Active Learning and Robotics to Discover the Function of Genes
- 2001
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- We aim to partially automate some aspects of scientific work, namely the processes of forming hypotheses, devising trials to discriminate between these competing hypotheses, physically performing these trials and then using the results of these trials to converge upon an accurate hypothesis. We have developed ASE-Progol, an Active Learning system which uses Inductive Logic Programming to construct hypothesised first-order theories and uses a CART-like algorithm to select trials for eliminating ILP derived hypotheses. We have developed a novel form of learning curve, which in contrast to the form of learning curve normally used in Active Learning, allows one to compare the costs incurred by different leaning strategies.We plan to combine ASE-Progol with a standard laboratory robot to create a general automated approach to Functional Genomics. As a first step towards this goal, we are using ASE-Progol to rediscover how genes participate in the aromatic amino acid pathway of Saccharomyces cerevisiae. Our approach involves auxotrophic mutant trials. To date, ASE-Progol has conducted such trials in silico. However we describe how they will be performed automatically in vitro by a standard laboratory robot designed for these sorts of liquid handling tasks, namely the Beckman/Coulter Biomek 2000.Although our work to date has been limited to trials conducted in silico, the results have been encouraging. Parts of the model were removed and the ability of ASE-Progol to efficiently recover the performance of the model was measured. The cost of the chemicals consumed in converging upon a hypothesis with an accuracy in the range 46-88% was reduced if trials were selected by ASE-Progol rather than if they were sampled at random (without replacement). To reach an accuracy in the range 46-80%, ASE-Progol incurs five orders of magnitude less experimental costs than random sampling. ASE-Progol requires less time to converge upon a hypothesis with an accuracy in the range 74-87% than if trials are sampled at random (without replacement) or selected using the naive strategy of always choosing the cheapest trial from the set of candidate trials. For example to reach an accuracy of 80%, ASE-Progol requires 4 days while random sampling requires 6 days and the naive strategy requires 10 days.
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| 4. |
- Gårdfeldt, Katarina, 1959, et al.
(författare)
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Evasion of Mercury from coastal and open waters of the Atlantic ocean and the Mediterranean sea
- 2003
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Ingår i: Atmospheric Environment. - 1352-2310 .- 1873-2844. ; 37:Suppl 1
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Tidskriftsartikel (refereegranskat)abstract
- Dissolved gaseous mercury (DGM) was measured in coastal Atlantic seawater and in the Mediterranean Sea. The Atlantic measurements were performed during September 1999 at the Mace Head Atmospheric Research Station, situated on the Irish west coast. The measurements in the Mediterranean Sea were made along a 6000 km cruise path from 14 July to 9 August 2000 in the framework of the Med-Oceanor project. Total gaseous mercury (TGM) concentrations in air were continuously measured with a 5 min time resolution using an automated mercury analyser (Tekran 2537A) during both expeditions. Paired TGM and DGM samples from all campaigns showed that the surface water was supersaturated with elemental mercury. The mercury evasion was estimated using a gas exchange model (J. Geophys. Res. 97 (1992) 7373), which uses salinity, wind speed and water temperature as independent parameters. The predicted average mercury evasion from the coastal Atlantic water was 2.7 ng m−2 h−1 implying that the concentration of TGM in the Atlantic air is enhanced by mercury evasion from the sea. Measurements in different regions of the Mediterranean Sea showed spatial variations in DGM concentrations. The highest DGM concentration (90 pg l−1) was observed at a location in the Strait of Sicily (37°16N 11°52E). The mercury evasion in the eastern sector of the Mediterranean Sea (area: 32–36°N, 17–28°E) was generally higher (7.9 ng m−2 h−1) than that observed in the Tyrrhenian Sea (4.2 ng m−2 h−1) or in the western sector (2.5 ng m−2 h−1) (areas: 38–42°N, 8–13°E and 38–41°N, 7–8°E, respectively). Estimations of mercury evasion were also made at Mediterranean coastal sites using a dynamic chamber technique. In addition, a newly developed method making continuous in situ DGM measurements possible was tested.
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| 5. |
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| 6. |
- Tran, K. Q., et al.
(författare)
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A novel particle trap impactor for use with the gas-quenching probe sampling system
- 2004
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Ingår i: Aerosol Science and Technology. - : Informa UK Limited. - 0278-6826 .- 1521-7388. ; 38:10, s. 955-962
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Tidskriftsartikel (refereegranskat)abstract
- A novel particle trap impactor has been developed for use with the gas-quenching probe in order to exclude solid particles from entering into the probe during sampling of gaseous metallic species in fluidized bed combustion conditions. The impactor must be small in size (empty set(impactor)less than or equal toempty set(probe) = 45 mm) but capable of collecting a relatively large amount of particles at elevated temperatures. As the first step, the impactor was designed, constructed, and tested at room temperature for KCl aerosol particles. The impactor with a nozzle of 0.95 mm in diameter, in combination with the orifice-to-jet diameter ratio of 1.5 and the ratio of the jet-to-plate spacing to jet diameter at 1.4 yielded a sharp cutoff curve with a maximum collection efficiency of about 0.9 and a rootStk(50) value of about 0.22. In addition, the collection efficiency of the impactor was compared with the particle removal efficiency of a filter of the same type as the filter previously used with the gas-quenching probe. The difference from the comparison is very small, indicating that the impactor can be used to replace the filter to prevent fly ash particles from entering the gas-quenching probe in fluidized bed combustion conditions.
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| 7. |
- Tran, K. Q., et al.
(författare)
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On the application of surface ionization detector for the study of alkali capture by kaolin in a fixed bed reactor
- 2004
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Ingår i: Fuel. ; 83:7-8, s. 807-812
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Tidskriftsartikel (refereegranskat)abstract
- Alkali metals, mainly potassium, together with other ash forming inorganic components in biomass are believed to be responsible for bed agglomeration in fluidized bed boilers burning biomass. A solution to the problem is to capture alkali vapor released from the fuel during combustion by inorganic solid additives such as kaolin. In this study, the capture of vaporous potassium chloride was investigated in a fixed bed reactor equipped with an on-line alkali detector. The detector, which is based on surface ionization, is capable of operating at alkali metal concentrations as low as those encountered after reaction with kaolin during biomass combustion (of the order of 1 ppb). Various experiments of KCl capture by kaolin powder were made at a reactor temperature of 850 degreesC. Kaolin removed up to 99% of alkali species in gas phase. The efficiency slightly decreased when KCl concentration decreased. The effect of kaolin addition on the release of alkali metals during wood combustion was studied at 650 degreesC in air. During pyrolysis, the alkali metal release increased slightly when kaolin was mixed with the wood due to the release of alkali metal impurities in the kaolin additive. The alkali metal release during char combustion was reduced to approximately 50% of the original value. The reduction increased as the amount of kaolin addition increased. Overall, the addition of kaolin suppressed the alkali metal release from the wood by approximately 20%. (C) 2004 Elsevier Ltd. All rights reserved.
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| 8. |
- Wessley, O, et al.
(författare)
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Final state effects in the X-ray absorption spectra of La0.7Sr0.3MnO3
- 2004
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853. ; 272-276:3, s. 1780-1781
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Tidskriftsartikel (refereegranskat)abstract
- We present a comparison of theoretical calculations of the electronic structure of La0.7Sr0.3MnO3 with measurements of the unoccupied local density of states for Mn obtained from X-ray absorption spectroscopy (XAS). We compare two different theoretical calculations of the Mn XAS spectra, one based on the local spin density approximation (LSDA) and the other one based on an atomic Hartree–Fock calculation for the Mn ions. In the atomic calculation the solid state effects are introduced through a cubic crystal field where the crystal field strength is obtained from the LSDA calculation. It is found that the atomic calculations agree better with experimental data.
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| 9. |
- Wirsel, SGR, et al.
(författare)
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Four or more species of Cladosporium sympatrically colonize Phragmites australis
- 2002
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Ingår i: Fungal Genetics and Biology. - : Elsevier BV. - 1087-1845. ; 35:2, s. 99-113
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Tidskriftsartikel (refereegranskat)abstract
- A collection of Cladosporium has been recovered from common reed growing at Lake Constance (Germany). High-resolution cryo-scanning electron microscopy revealed that Cladosporium isolates from reed are diverse. Morphologically, we distinguished three species, viz. C. herbarum, C. oxysporum, and Cladosporium sp. Internal transcribed spacer (ITS) sequence analysis supported these results and, moreover, separated the most common species, C. oxysporum, into two subclades. Two additional phylogenies were generated to gain support for this finding. The first, differentiating fungi by their capacities to metabolize different carbon sources, showed correlation with morphology. The second, based on actin gene sequences, showed the same overall topology as that of the ITS tree, but resulted in a higher resolution indicating the existence of four or more species of Cladosporium on reed. A nested PCR assay targeting variable sequences within actin introns indicated that these four species sympatrically colonize reed. There was no evidence for mutual exclusion on or within the host or specialization for host habitats or organs.
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