| 1. |
- Abreu, P., et al.
(författare)
-
Study of dimuon production in photon-photon collisions and measurement of QED photon structure functions at LEP
- 2001
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 19:1, s. 15-28
-
Tidskriftsartikel (refereegranskat)abstract
- Muon pair production in the process e+e- → e+e- μ+μ- is studied using the data taken at LEP1 (√s ≃ mz) with the DELPHI detector during the years 1992-1995. The corresponding integrated luminosity is 138.5 pb-1. The QED predictions have been tested over the whole Q2 range accessible at LEP1 (from several GeV2/c4 to several hundred GeV2/c4) by comparing experimental distributions with distributions resulting from Monte Carlo simulations using various generators. Selected events are used to extract the leptonic photon structure function Fγ 2. Azimuthal correlations are used to obtain information on additional structure functions, Fγ A and Fγ B, which originate from interference terms of the scattering amplitudes. The measured ratios Fγ A/Fγ 2 and FγB/Fγ 2 are significantly different from zero and consistent with QED predictions.
|
|
| 2. |
- Abreu, P., et al.
(författare)
-
Search for sleptons in e+e- collisions at √s = 183 to 189 GeV
- 2001
-
Ingår i: European Physical Journal C. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 19:1, s. 29-42
-
Tidskriftsartikel (refereegranskat)abstract
- Data taken by the DELPHI experiment at centre-of-mass energies of 183 GeV and 189 GeV with a total integrated luminosity of 212 pb-1 have been used to search for the supersymmetric partners of the electrons, muons, and taus in the context of the Minimal Supersymmetric Standard Model (MSSM). The decay topologies searched for were the direct decay (ℓ̃ → ℓx̃), producing acoplanar lepton pairs plus missing energy, and the cascade decay (ℓ → ℓx̃0 2 → ℓγx̃0 1), producing acoplanar lepton and photon pairs plus missing energy. The observed number of events is in agreement with Standard Model predictions. The 95% CL excluded mass limits for selectrons, smuons and staus are mẽ ≤ 87 GeV/c2, mμ̃ ≤ 80 GeV/c2 and mτ̃ 75 GeV/c2, respectively, for values of μ=-200 GeV/c2 and tanβ=1.5.
|
|
| 3. |
- Eriksson, M., et al.
(författare)
-
Degradation of polycyclic aromatic hydrocarbons at low temperature under aerobic and nitrate-reducing conditions in enrichment cultures from northern soils
- 2003
-
Ingår i: Applied and Environmental Microbiology. - : American Society for Microbiology. - 0099-2240 .- 1098-5336. ; 69:1, s. 275-284
-
Tidskriftsartikel (refereegranskat)abstract
- The potential for biodegradation of polycyclic aromatic hydrocarbons (PAHs) at low temperature and under anaerobic conditions is not well understood, but such biodegradation would be very useful for remediation of polluted sites. Biodegradation of a mixture of 11 different PAHs with two to five aromatic rings, each at a concentration of 10 mug/ml, was studied in enrichment cultures inoculated with samples of four northern soils. Under aerobic conditions, low temperature severely limited PAH biodegradation. After 90 days, aerobic cultures at 20degreesC removed 52 to 88% of the PAHs. The most extensive PAH degradation under aerobic conditions at 7degreesC, 53% removal, occurred in a culture from creosote-contaminated soil. Low temperature did not substantially limit PAH biodegradation under nitrate-reducing conditions. Under nitrate-reducing conditions, naphthalene, 2-methyl naphthalene, fluorene, and phenanthrene were degraded. The most extensive PAH degradation under nitrate-reducing conditions at 7degreesC, 39% removal, occurred in a culture from fuel-contaminated Arctic soil. In separate transfer cultures from the above Arctic soil, incubated anaerobically at 7degreesC, removal of 2-methylnaphthalene and fluorene was stoichiometrically coupled to nitrate removal. Ribosomal intergenic spacer analysis suggested that enrichment resulted in a few predominant bacterial populations, including members of the genera Acidovorax, Bordetella, Pseudomonas, Sphingomonas, and Variovorax. Predominant populations from different soils often included phylotypes with nearly identical partial 16S rRNA gene sequences (i.e., same genus) but never included phylotypes with identical ribosomal intergenic spacers (i.e., different species or subspecies). The composition of the enriched communities appeared to be more affected by presence of oxygen, than by temperature or source of the inoculum.
|
|
| 4. |
|
|
| 5. |
- Svensson, M, et al.
(författare)
-
A small reduction in glomerular filtration is accompanied by insulin resistance in type I diabetes patients with diabetic nephrophathy.
- 2002
-
Ingår i: European Journal of Clinical Investigation. - 0014-2972 .- 1365-2362. ; 32:2, s. 100-9
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Insulin sensitivity and insulin clearance are compromised in end-stage renal disease but it has not been fully established whether they are altered in earlier stages of diabetic nephropathy.DESIGN: We studied three groups of patients with type 1 diabetes; 10 with no sign of nephropathy, 11 with albuminuria (> 20 microg min-1) but normal glomerular filtration rate (GFR) and eight with a small reduction in GFR, (43-73 mL min-1 1.73 m-2). The groups were matched for age (range 36-61 years), body mass index (BMI), diabetes duration and glycaemic control. The euglycaemic hyperinsulinaemic clamp technique was utilized to study insulin sensitivity (M-value) and metabolic clearance rate for insulin. Needle biopsies from abdominal subcutaneous fat tissue were obtained to study insulin binding, insulin degradation, insulin-stimulated glucose uptake and anti-lipolysis in adipocytes in vitro.RESULTS: Patients with reduced GFR were more insulin-resistant (M-value 5.7 +/- 0.7 mg kg LBM-1 min-1) than those without nephropathy (9.6 +/- 0.7, P = 0.001) and those with only albuminuria (8.9 +/- 1.2, P = 0.044). In all subjects taken together there was a strong association between insulin sensitivity and GFR (r = 0.46, P = 0.012). Patients with reduced GFR displayed no significant difference in insulin clearance (12.2 +/- 1.6 mL kg-1 min-1) compared to controls (13.8 +/- 1.3) but a slightly lower insulin clearance than patients with only albuminuria (16.6 +/- 1.0, P = 0.027). There were no significant differences between patient groups in the adipocyte studies in vitro, i.e. with respect to insulin binding, insulin degradation and the effects of insulin on glucose uptake and lipolysis. This is compatible with humoral factors causing whole-body insulin resistance and in the group with reduced GFR, we found that serum parathyroid hormone, interleukin-6 and tumour necrosis factor-alpha levels were elevated whereas the morning cortisol was decreased.CONCLUSIONS: In type 1 diabetes, the appearance of albuminuria does not seem to alter insulin sensitivity and clearance. A marked insulin resistance but no consistent impairment in insulin clearance seems to accompany progression to a stage with a slight reduction in GFR. These alterations are not accompanied by general defects in insulin target cells. Instead, alterations in the regulation of insulin-antagonistic hormones and cytokines could potentially contribute to the development of insulin resistance in diabetic nephropathy.
|
|
| 6. |
- Yu, Z W, et al.
(författare)
-
Insulin can enhance GLUT4 gene expression in 3T3-F442A cells and this effect is mimicked by vanadate but counteracted by cAMP and high glucose--potential implications for insulin resistance.
- 2001
-
Ingår i: Biochimica et Biophysica Acta. - 0006-3002 .- 1878-2434. ; 1535:2, s. 174-85
-
Tidskriftsartikel (refereegranskat)abstract
- It is well-established that high levels of cAMP or glucose can produce insulin resistance. The aim of this study was to characterize the interaction between these agents and insulin with respect to adipose tissue/muscle glucose transporter isoform (glucose transporter 4, GLUT4) gene regulation in cultured 3T3-F442A adipocytes and to further elucidate the GLUT4-related mechanisms in insulin resistance. Insulin (10(4) microU/ml) treatment for 16 h clearly increased GLUT4 mRNA level in cells cultured in medium containing 5.6 mM glucose but not in cells cultured in medium with high glucose (25 mM). 8-Bromo-cAMP (1 or 4 mM) or N(6)-monobutyryl cAMP, a hydrolyzable and a non-hydrolyzable cAMP analog, respectively, markedly decreased the GLUT4 mRNA level irrespective of glucose concentrations. In addition, these cAMP analogs also inhibited the upregulating effect of insulin on GLUT4 mRNA level. Interestingly, the tyrosine phosphatase inhibitor vanadate (1-50 microM) clearly increased GLUT4 mRNA level in a time- and concentration-dependent manner. Furthermore, cAMP-induced inhibition of the insulin effect was also prevented by vanadate. In parallel to the effects on GLUT4 gene expression, both insulin, vanadate and cAMP produced similar changes in cellular GLUT4 protein content and cAMP impaired the effect of insulin to stimulate (14)C-deoxyglucose uptake. In contrast, insulin, vanadate or cAMP did not alter insulin receptor (IR) mRNA or the cellular content of IR protein. In conclusion: (1) Both insulin and vanadate elicit a stimulating effect on GLUT4 gene expression in 3T3-F442A cells, but a prerequisite is that the surrounding glucose concentration is low. (2) Cyclic AMP impairs the insulin effect on GLUT4 gene expression, but this is prevented by vanadate, probably by enhancing the tyrosine phosphorylation of signalling peptides and/or transcription factors. (3) IR gene and protein expression is not altered by insulin, vanadate or cAMP in this cell type. (4) The changes in GLUT4 gene expression produced by cAMP or vanadate are accompanied by similar alterations in GLUT4 protein expression and glucose uptake, suggesting a role of GLUT4 gene expression for the long-term regulation of cellular insulin action on glucose transport.
|
|
| 7. |
- Yu, Z W, et al.
(författare)
-
The upregulating effect of insulin and vanadate on cell surface insulin receptors in rat adipocytes is modulated by glucose and energy availability.
- 2000
-
Ingår i: Hormone and Metabolic Research. - : Georg Thieme Verlag KG. - 0018-5043 .- 1439-4286. ; 32:8, s. 310-5
-
Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to further characterize the rapid effects of insulin and the tyrosine phosphatase inhibitor vanadate to amplify cell surface insulin binding capacity in isolated rat adipocytes. The effect of 20 min insulin treatment (1000 microU/ml) was 2- to 3-fold (p < 0.01) when cells were treated in medium containing 5.6 mM D-glucose, but it was totally absent in glucose-free medium. Other carbon energy sources, such as fructose and pyruvate, could only partly substitute for D-glucose, with an approximately 1.5-fold insulin effect. Moreover, inhibiting transmembrane glucose transport with cytochalasin B completely blocked the effect of insulin to enhance cell surface binding. The effect of vanadate was only partly glucose-dependent, since a submaximal effect (1.5- to 2-fold, p<0.05) was seen also in the absence of glucose. The tyrosine kinase inhibitor genistein markedly blunted the effect of vanadate (from 3- to 4-fold to approximately 2-fold, p < 0.05) also indicating the importance of tyrosine phosphorylation-related mechanisms in the upregulation of cell surface insulin binding. Glycosylation of insulin receptors as a mechanism for this effect appears unlikely since neither the effect of insulin nor that of vanadate was altered by the glycosylation inhibitor tunicamycin. The time course for the insulin effect displayed a long duration (at least 6 h), suggesting a maintenance role of insulin keeping its receptors accessible for ligand binding at the cell surface. In conclusion, the effect of insulin and vanadate to upregulate cell-surface insulin receptors is energy-dependent and to some extent specifically glucose-dependent.
|
|
| 8. |
- Zheng, W.T., et al.
(författare)
-
Chemical bonding, structure, and hardness of carbon nitride thin films
- 2000
-
Ingår i: Diamond and related materials. - 0925-9635 .- 1879-0062. ; 9:9-10, s. 1790-1794
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Carbon nitride films are deposited on Si(001) substrates by reactive d.c. magnetron sputtering graphite in a pure N2 discharge. The chemical bonding and structure of carbon nitride films were probed using Fourier transformation infrared (FTIR) and near edge X-ray absorption fine structure (NEXAFS), and the hardness was evaluated using nanoindentation experiments. The structure and hardness for the films are dependent on the substrate temperature (T(s)). FTIR and NEXAFS spectra show that N atoms are bound to sp1, sp2 and sp3 hybridized C atoms, and the intensity of p(*) resonance for C1s NEXAFS spectra is the lowest for the film grown at T(s) = 350°C, having a turbostratic-like structure, high hardness and stress. The correlation between the structure and hardness of carbon nitride films is discussed. (C) 2000 Elsevier Science S.A. All rights reserved.Carbon nitride films are deposited on Si(001) substrates by reactive d.c. magnetron sputtering graphite in a pure N2 discharge. The chemical bonding and structure of carbon nitride films were probed using Fourier transformation infrared (FTIR) and near edge X-ray absorption fine structure (NEXAFS), and the hardness was evaluated using nanoindentation experiments. The structure and hardness for the films are dependent on the substrate temperature (Ts). FTIR and NEXAFS spectra show that N atoms are bound to sp1, sp2 and sp3 hybridized C atoms, and the intensity of p* resonance for C1s NEXAFS spectra is the lowest for the film grown at Ts = 350°C, having a turbostratic-like structure, high hardness and stress. The correlation between the structure and hardness of carbon nitride films is discussed.
|
|
| 9. |
- Boukhvalov D. W., Kurmaev E. Z. , Moewes A. , Zatsepin D. A., Cherkashenko V. M., Nemnonov S. N., Finkelstein L. D. , Yarmoshenko Yu. M., Neumann M., Dobrovitski V. V. , Katsnelson M. I. , Lichtenstein A. I. , Harmon B. N. , Kögerler P.
(författare)
-
Electronic structure of magnetic molecules V15: LSDA+U calculations, X-ray emission and photoelectron spectra
- 2003
-
Ingår i: Physical Review B. ; 67, s. 134408-
-
Tidskriftsartikel (refereegranskat)
|
|
| 10. |
|
|
