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- Hemmers, O, et al.
(författare)
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Beyond the dipole approximation: angular-distribution effects in valence photoemission
- 1997
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - 0953-4075. ; 30:21, s. L727-L733
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Tidskriftsartikel (refereegranskat)abstract
- Angular distributions of valence photoelectrons showing effects due to highermultipole photon interactions have been measured for the first time. Neon 2s and 2p photoemission exhibits effects beyond the dipole approximation throughout the 250 to 1200 eV photon-energy range studied. The results suggest that any photoemission experiment, on any sample, can be affected at relatively low photon energies, pointing to a general need for caution in interpreting angle-resolved-photoemission measurements.
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- Prakobphol, A, et al.
(författare)
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Human low-molecular-weight salivary mucin expresses the sialyl lewisx determinant and has L-selectin ligand activity.
- 1998
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Ingår i: Biochemistry. - : American Chemical Society (ACS). - 0006-2960 .- 1520-4995. ; 37:14, s. 4916-27
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Tidskriftsartikel (refereegranskat)abstract
- Previously we showed that the low-molecular-weight mucin (MG2, encoded by MUC7), a major component of human submandibular/sublingual saliva, is a bacterial receptor that coats the tooth surface. Here we tested the hypothesis that the structure of its carbohydrate residues contains important information about its function. Purified MG2 (Mr 120 000) was digested with trypsin, and the resulting Mr 90 000 fragment, which carried primarily O-linked oligosaccharides, was subjected to reductive beta-elimination. The released oligosaccharides were characterized by using nuclear magnetic resonance spectroscopy and mass spectrometry. Of the 41 different structures we detected, the most prominent included NeuAcalpha2-->3Galbeta1-->3GalNAc-ol (sialyl-T antigen), Galbeta1-->4(Fucalpha1-->3)GlcNAcbeta1-->6(Galbeta1 -->3)GalNAc-ol [type 2 core with Lewisx (Lex) determinant], and NeuAcalpha2-->3Galbeta1-->4(Fucalpha1-->3)GlcNAcbet a1-->6(Galbeta1--> 3) GalNAc-ol [type 2 core with sialyl Lex (sLex) determinant]. We also detected di-, tri-, and pentasaccharides with one sulfate group. Lex, sLex, and related sulfated structures are ligands for selectins, adhesion molecules that mediate leukocyte trafficking. Therefore, we investigated whether MG2 was a selectin ligand. In an enzyme-linked immunosorbent assay, L-selectin chimeras interacted with immobilized MG2 in a Ca2+-dependent manner. L-Selectin chimeras also bound to MG2 immobilized on nitrocellulose. Together, these results suggest that the saccharides that MG2 carries could specify some of its important functions, which may include mediating leukocyte interactions in the oral cavity.
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- Ohlsson, R, et al.
(författare)
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Random monoallelic expression of the imprinted IGF2 and H19 genes in the absence of discriminative parental marks
- 1999
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Ingår i: Dev Genes and Evolution. ; 209, s. 113-
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Tidskriftsartikel (refereegranskat)abstract
- PDGFB is a growth factor which is vital for the completion of normal prenatal development. In this study, we report the phenotypic analysis of placentas from mouse conceptuses that lack a functional PDGFB or PDGFRbeta gene. Placentas of both types of mutant exhibit changes in the labyrinthine layer, including dilated embryonic blood vessels and reduced numbers of both pericytes and trophoblasts. These changes are seen from embryonic day (E) 13.5, which coincides with the upregulation of PDGFB mRNA levels in normal placentas. By E17, modifications in shape, size, and number of the fetal blood vessels in the mutant placentas cause an abnormal ratio of the surface areas between the fetal and the maternal blood vessels in the labyrinthine layer. Our data suggest that PDGFB acts locally to contribute to the development of the labyrinthine layer of the fetal placenta and the formation of a proper nutrient-waste exchange system during fetal development. We point out that the roles of PDGFB/Rbeta signaling in the placenta may be analogous to those in the developing kidney, by controlling pericytes in the labyrinthine layer and mesangial cells in the kidney.
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- Niu, Steve S., et al.
(författare)
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A Tutorial On Multiple Model Least-Squares and Augmented UD Identification
- 1995
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The augmented UD identification (AUDI) is a family of new identification algorithms that are based on some well-known matrix decomposition and updating techniques. Compared with conventional least-squares methods, the AUDI methods are conceptually more concise, computationally more efficient, numerically more robust and application-wise more complete. As a result, AUDI is recommended as a complete replacements for conventional recursive least-squares in all parameter estimation and system identification applications. This tutorial paper presents an overview of the AUDI concept, implementation and applications. The multiple model least-squares (MMLS) method, which is a fundamental reformulation and an efficient implementation of the basic least-squares method, is discussed first. Some application examples of the MMLS/AUDI are presented to demonstrate the versatility and reliability of this type of algorithms.
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