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| 2. |
- Böhm, S, et al.
(författare)
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Enhancement of dielectronic recombination by external electromagnetic fields
- 2003
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Ingår i: Hyperfine Interactions. - 0304-3843. ; 146-147:1-4, s. 23-27
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Tidskriftsartikel (refereegranskat)abstract
- The enhancement of the dielectronic recombination rate of lithiumlike Ne7+ and O5+ ions by external electromagnetic fields has been measured at the storage ring CRYRING. The energy range covered all 1s(2)2pnl dielectronic recombination resonances attached to the 2s --> 2p core excitation. Electric fields up to 1436 V/cm were applied in the Ne7+ experiment and the saturation of the enhancement with increasing electric field could clearly be seen. In the O5+ experiment the enhancement was studied as a function of the Rydberg quantum number n.
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| 3. |
- Böhm, S, et al.
(författare)
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Influence of electromagnetic fields on the dielectronic recombination of Ne7+ and O5+ ions
- 2001
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Ingår i: Physica Scripta. Topical Issues. - 0281-1847. ; T92, s. 395-397
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Tidskriftsartikel (refereegranskat)abstract
- Within a series of measurements of the dielectronic recombination (DR) of lithium-like ions we have determined the enhancement of the recombination rate in the presence of crossed electric and magnetic fields for Ne7+ and O5+ ions. In both cases the electron energy range covers a DR resonances attached to 2s --> 2p(1/2) and 2s --> 2p(3/2) Delta_n = 0 core excitations. For increasing field the enhancement factor first increases linearly with the electric field and then saturates. In order to investigate the field effect on high-n Rydberg states the ion energy in the O5+ experiment was changed from 9.4 MeV/u to 5 MeV/u and 3.26 MeV/u. With the variation of the ion energy the field ionization of Rydberg states in the analyzing magnet is influenced. This enabled us to study the field enhancement for a narrow bandwidth of n-states.
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| 4. |
- Böhm, S, et al.
(författare)
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Influence of electromagnetic fields on the dielectronic recombination of Ne7+ ions
- 2001
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - 1050-2947. ; 64:3, s. 032707/1-032707/7
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Tidskriftsartikel (refereegranskat)abstract
- The influence of crossed electric and magnetic fields on dielectronic recombination of Ne7+ ions has been measured at the Stockholm heavy-ion storage ring CRYRING. The electron energy range covered all dielectronic recombination resonances attached to 2s-2p1/2 and 2s-2p3/2 core excitations. Two sets of measurements at magnetic fields of 180 mT and 30 mT have been performed. For the measurement at 180 mT we applied 25 different electric fields between 0 and 1400 V/cm. The resonance strength for dielectronic recombination via high Rydberg states initially increases linearly with electric field and later levels out. At a magnetic field of 30 mT we applied 15 different electric fields ranging from 0 to 140 V/cm. Compared to the measurement at 180 mT the initial slope of the rate enhancement was larger by almost a factor of 2. The fraction of resonant strength not measured due to field ionization is estimated by a model calculation of dielectronic recombination cross sections.
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| 5. |
- Gadjeva, M, et al.
(författare)
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Mannan-binding lectin modulates the response to HSV-2 infection.
- 2004
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Ingår i: Clinical and experimental immunology. - : Oxford University Press (OUP). - 0009-9104 .- 1365-2249. ; 138:2, s. 304-11
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Tidskriftsartikel (refereegranskat)abstract
- Viruses have developed numerous strategies to escape recognition by the immune system. However, some viruses such as herpes simplex virus-2 (HSV-2) are recognized by initiators of the complement system, e.g. mannan-binding lectin (MBL). To study the effects of MBL deficiency during viral infection we have chosen a model of generalized HSV-2 infection. We infected MBL-A and MBL-C double knock-out mice (DKO) with HSV-2 via the intraperitoneal (i.p.) route. DKO mice cleared HSV-2 from the liver less efficiently than the comparable wild-type animals. The impairment to effectively neutralize HSV-2 correlated with compromised liver function as measured by increased plasma levels of alanine-amino transferase. No differences in the viral burden were found in other organs such as spleen or brain. Thus, MBL-mediated protection was limited to the effects of preservation of liver homeostasis. Reconstitution with recombinant human MBL before and during the HSV-2 infection dramatically lowered the viral titres in the liver. Taken together, the data show that MBL modulates the response to HSV-2 in mice by affecting neutralization of the virus. To analyse if MBL plays a role in establishment and progression of human HSV-2 infection we analysed MBL levels in the serum samples from asymptomatic (virus-exposed people who have never displayed symptoms of HSV-2 infection) and symptomatic HSV-2 patients (people with recurrent HSV-2 infections). We found that the frequency of the MBL deficiency (<100 ng/ml) was higher in the symptomatic group and significantly different from that in the asymptomatic group (P = 0.0369). This suggests that lack of MBL-mediated complement activation increases susceptibility to viral infection.
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| 6. |
- Persson-Sjögren, S, et al.
(författare)
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Mouse islets cultured with vasoactive intestinal polypeptide : effects on insulin release and immunoreactivity for tyrosine hydroxylase.
- 2001
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Ingår i: Pancreas. - 0885-3177 .- 1536-4828. ; 22:1, s. 84-90
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Tidskriftsartikel (refereegranskat)abstract
- Mouse islets cultured for 1 or 4 days with or without 10 nM vasoactive intestinal polypeptide (VIP) were stained for tyrosine hydroxylase (TH) and examined for insulin secretion during culture and in a postculture perifusion system. Exposure to exogenous VIP for 4 days increased the frequency of islet cells expressing TH-like immunoreactivity. Regardless of the culturing conditions, the islets exhibited significant insulin secretory responses to 16.7 mM glucose, the effect being potentiated by 10 nM VIP in the perifusion medium. The insulin-releasing action of glucose and the potentiating effect of VIP were less pronounced in islets cultured for 1 day with VIP than in islets cultured without this neuropeptide. The following conclusions are suggested: (a) VIP stimulates the expression of TH in mouse islet cells; (b) the latency of the VIP-induced TH is a postreceptor phenomenon; (c) islet cultures exposed to VIP represent a new instance of the association between increased functional demands on beta cells and enhanced expression of TH and a new instance of VIP having trophic effects.
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| 7. |
- Zhang, Shi-Li, et al.
(författare)
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Abnormal anti-Stokes Raman scattering of carbon nanotubes
- 2002
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 66:3
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Tidskriftsartikel (refereegranskat)abstract
- Abnormal anti-Stokes Raman scattering (AASR) was unambiguously observed in carbon nanotubes (CNT's). In contrast to traditional Raman scattering theory, the absolute value of the Raman frequency of the anti-Stokes peak is not the same as that of the corresponding Stokes peak. It was demonstrated that AASR scattering originates from the unique nanoscale cylindrical structure of CNT's that can be considered naturally as a graphite structure with an intrinsic defect from its rolling. The double-resonance Raman scattering theory was applied to interpret the scattering mechanism of the AASR phenomenon successfully and quantitatively.
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| 8. |
- Aberg, J, et al.
(författare)
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Electrical properties of the TiSi2-Si transition region in contacts : The influence of an interposed layer of Nb
- 2001
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 90:5, s. 2380-2388
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Tidskriftsartikel (refereegranskat)abstract
- The influence of an interposed ultrathin Nb layer between Ti and Si on the silicide formation and the electrical contact between the silicide formed and the Si substrate is investigated. The presence of the Nb interlayer results in the formation of ternary alloy (Nb,Ti)Si-2 in the C40 crystallographic structure adjacent to the Si substrate. Depending on the nature of the Si substrates and/or the amount of the initial Nb, the interfacial C40 (Nb,Ti)Si-2 leads, in turn, to either epitaxial growth of a highly faulted metastable C40 TiSi2 or formation of the desired C54 TiSi2 at a lower temperature than needed for it to form in reference samples with Ti deposited directly on Si. On p-type substrates doped to various concentrations, the Nb also leads to a considerably lower specific contact resistivity than that obtained in the reference samples: a twofold to fourfold reduction in the contact resistivity is found using cross-bridge Kelvin structures in combination with two-dimensional numerical simulation. As C40 (Nb,Ti)Si-2 forms at the interface when an interfacial Nb is present, the interface characterized is likely to represent the one between (Nb,Ti)Si-2 and Si. For the reference samples, the interface studied is between TiSi2 and Si.
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| 10. |
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