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| 2. |
- Fritioff, Karin, et al.
(författare)
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Observation of an excited C2-4 ion
- 2004
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 37:11, s. 2241-2246
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports an experimental investigation of the electron impact detachment of C−4. We observe structure in the electron impact cross section for detaching a single electron from a C−4 cluster anion, which we attribute to the formation and decay of the C2−4 dianion. The system is energetically unstable and very rapidly decays via double autodetachment. The energy and width of the resonance were determined to be 8.8(5) eV and 1.4(5) eV, respectively, and the resonance lies 1.5(5) eV above the ground state of the neutral system. The experiment was conducted by merging monoenergetic electron and ion beams in the heavy ion storage ring CRYRING. The detachment channel was monitored by detecting neutral C4 fragments.
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| 3. |
- Fritioff, K, et al.
(författare)
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Single and double detachment from H-
- 2004
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947 .- 1094-1622 .- 2469-9926 .- 2469-9934. ; 69:4, s. 042707-
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Tidskriftsartikel (refereegranskat)abstract
- Absolute cross sections for single and double detachment from H- following electron impact have been measured over a range of collision energies from the thresholds to 170 eV. The measurements were made using a magnetic storage ring. The ions in the ring were merged with a monoenergetic electron beam and neutral and positively charged fragments were detected. We cover larger energy ranges than in many of the previous experiments, and this is the first time both single and double detachment have been measured simultaneously. This allows us to present accurate ratios between the single and double detachment cross sections. On the basis of these ratio measurements we discuss possible mechanisms leading to double detachment.
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| 4. |
- Gibson, R. N., et al.
(författare)
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Ontogenetic changes in depth distribution of juvenile flatfishes in relation to predation risk and temperature on a shallow-water nursery ground
- 2002
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Ingår i: Marine Ecology-Progress Series. - 0171-8630. ; 229, s. 233-244
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Tidskriftsartikel (refereegranskat)abstract
- Stratified depth sampling was used to investigate the distributional changes of newly settled plaice Pleuronectes platessa and dabs Limanda limanda, and resident populations of shrimp Crangon crangon on a sandy beach. During the settlement period, the smallest newly settled plaice are found in deeper water than the larger fish that settled earlier. After settlement, plaice concentrate in water <1 m deep and there is a positive relationship between length and depth. Later in the year the fish gradually migrate into deeper water as they grow. Dabs settle later and in deeper water than plaice. Shrimp are concentrated in deeper water early in the year but migrate onshore in the summer, The movements of plaice are considered to be related to the predation risk caused by the shrimp and other predators in deeper water and to the higher temperatures in shallow water that promote faster growth. Once a size refuge from predators has been reached, the plaice move into deeper water. Intertidal pools probably serve as refuges for the smallest sizes of plaice because predators are less numerous in pools than in the sea. The use of shallow water by plaice represents the occupation of a niche which not only reduces predation and maximises growth, but may also greatly reduce competition for food in the earliest stages when densities are highest and competition with dabs is likely to be greatest.
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| 5. |
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| 6. |
- Greetham, Hazel L., et al.
(författare)
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Sutterella sterconcanis sp nov., isolated from canine faeces
- 2004
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Ingår i: INTERNATIONAL JOURNAL OF SYSTEMATIC AND EVOLUTIONARY MICROBIOLOGY. - : Microbiology Society. - 1466-5026 .- 1466-5034. ; 54, s. 1581-1584
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Tidskriftsartikel (refereegranskat)abstract
- Morphological, biochemical and molecular genetic studies were carried out on an unknown non-spore-forming, Gram-negative, rod-shaped bacterium which was isolated from dog faeces. The bacterium grew under anaerobic conditions, was asaccharolytic, resistant to 20 % (v/v) bile and was oxidase- and urease-negative. Phylogenetic analysis based on comparative 16S rRNA gene sequencing showed that the unidentified bacterium clustered withSutterella wadsworthensis, although a sequence divergence of >5 % indicated that the bacterium from dog faeces represented a previously unrecognized subline within the genus. On the basis of the presented findings, a novel species,Sutterella stercoricanissp. nov., is described. The type strain ofSutterella stercoricanisis 5BAC4T(=CCUG 47620T=CIP 108024T).
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| 7. |
- Roberts, Sigrid C, et al.
(författare)
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Arginase plays a pivotal role in polyamine precursor metabolism in Leishmania. Characterization of gene deletion mutants.
- 2004
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Ingår i: J Biol Chem. - 0021-9258. ; 279:22, s. 23668-78
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Tidskriftsartikel (refereegranskat)abstract
- The polyamine pathway of protozoan parasites has been successfully targeted in anti-parasitic therapies and is significantly different from that of the mammalian host. To gain knowledge into the metabolic routes by which parasites synthesize polyamines and their precursors, the arginase gene was cloned from Leishmania mexicana, and Deltaarg null mutants were created by double targeted gene replacement and characterized. The ARG sequence exhibited significant homology to ARG proteins from other organisms and predicted a peroxisomal targeting signal (PTS-1) that steers proteins to the glycosome, an organelle unique to Leishmania and related parasites. ARG was subsequently demonstrated to be present in the glycosome, whereas the polyamine biosynthetic enzymes, in contrast, were shown to be cytosolic. The Deltaarg knockouts expressed no ARG activity, lacked an intracellular ornithine pool, and were auxotrophic for ornithine or polyamines. The ability of the Deltaarg null mutants to proliferate could be restored by pharmacological supplementation, either with low putrescine or high ornithine or spermidine concentrations, or by complementation with an arginase episome. Transfection of an arg construct lacking the PTS-1 directed the synthesis of an arg that mislocalized to the cytosol and notably also complemented the genetic lesion and restored polyamine prototrophy to the Deltaarg parasites. This molecular, biochemical, and genetic dissection of ARG function in L. mexicana promastigotes establishes: (i) that the enzyme is essential for parasite viability; (ii) that Leishmania, unlike mammalian cells, expresses only one ARG activity; (iii) that the sole vital function of ARG is to provide polyamine precursors for the parasite; and (iv) that ARG is present in the glycosome, but this subcellular milieu is not essential for its role in polyamine biosynthesis.
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| 8. |
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| 9. |
- Sprengers, JP, et al.
(författare)
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Lifetime and predissociation yield of N-14(2) b (1)Pi(u)(v=1)
- 2004
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 120:19, s. 8973-8978
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Tidskriftsartikel (refereegranskat)abstract
- The lifetime of the b (1)Pi(u)(v=1) state in N-14(2) has been determined experimentally using a laser-based pump-probe scheme and an exceptionally long lifetime of 2.61 ns was found. Semiempirical close-coupling calculations of the radiative lifetime, which include Rydberg-valence interactions in the singlet manifold, are consistent with this large value, giving a value of 3.61 ns and suggesting a predissociation yield of similar to28% for this level of the b state. (C) 2004 American Institute of Physics.
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