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- von Hofsten, Claes, et al.
(författare)
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Object representation and predictive action in infancy
- 2000
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Ingår i: Developmental Science. - Oxford, UK and Malden, USA : Blackwell Publishers Ltd.. - 1363-755X .- 1467-7687. ; 3:2, s. 193-205
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has shown that 6-month-old infants extrapolate object motion on linear paths when they act predictively on fully visible moving objects but not when they observe partly occluded moving objects. The present research probed whether differences in the tasks presented to infants or in the visibility of the objects account for these findings, by investigating infants’ predictive head tracking of a visible object that moves behind a small occluder. Six-month-old infants were presented with an object that moved repeatedly on linear or nonlinear paths, with an occluder covering the place where all the paths intersected. The first time infants viewed an object’s motion, their head movements did not anticipate either linear or nonlinear motion, but they quickly learned to anticipate linear motion on successive trials. Infants also learned to anticipate nonlinear motion, but this learning was slower and less consistent. Learning in all cases concerned the trajectory of the object, not the specific locations at which the object appeared. These findings suggest that infants form object representations that are weakly biased toward inertial motion and that are influenced by learning. The findings accord with the thesis that a single system of representation underlies both predictive action and perception of object motion, and that occlusion reduces the precision of object representations.
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- Zhang, L, et al.
(författare)
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Additive effects of leflunomide and tacrolimus in prevention of islet xenograft rejection
- 2004
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Ingår i: Scandinavian Journal of Immunology. - : Wiley. - 1365-3083 .- 0300-9475. ; 59:3, s. 255-260
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Tidskriftsartikel (refereegranskat)abstract
- Leflunomide is a low molecular weight immunosuppressive drug which inhibits the enzymes dehydroorotate dehydrogenase and protein tyrosine kinase, both of which are important components in the immune response. As the mechanisms of action of leflunomide and tacrolimus are different, we postulated an additive or synergistic effect of the two drugs and investigated the effects of leflunomide alone, or in combination with a suboptimal dose of tacrolimus, on xenogeneic islet transplantation in a rat-to-mouse model. A total of 1200-1500 rat islets were transplanted under the left kidney capsule of streptozotocin-induced diabetic BALB/c mice. The median survival time (MST) of the untreated group was 6 days. Leflunomide at 5, 10 and 20 mg/kg/d administrated for 10 days significantly prolonged MST to 10, 16 and 20 days. A dose of tacrolimus (2 mg/kg/d) was associated with a graft survival of 9 (range 6-12) days; most grafts rejected during ongoing therapy. When tacrolimus (2 mg/kg/d) was combined with leflunomide (10 mg/kg/d), the survival time of the islet xenografts was increased further to 22 days, significantly longer than with leflunomide or tacrolimus alone. In summary, our findings demonstrate that leflunomide prolonged xenogeneic islet graft survival, and that its immunosuppressive effect was improved when combined with tacrolimus.
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- Zhang, S, et al.
(författare)
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Gene variation of 5'-NCR and core region in serum samples collected from patients with HCV infection
- 2000
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Ingår i: Zhonghua gan zang bing za zhi. Chinese journal of hepatology. - 1007-3418. ; 8:3, s. 144-146
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: To study the variation of HCV 5'-NCR and core gene in serial sera collected from patients with HCV infection. METHODS: Serial sera were collected from 4 plasma-donors with HCV infection. 5'-NCR and core gene were amplified, sequenced and analyzed using software. RESULTS: All the sequences obtained from the serial sera of patients with HCV infection were 1b and 2a subtypes. The variation of 5'-NCR only related to the genotype, and not associated with patients and time of serum collection. However, the sequences of core gene were not identical in HCV strains isolated from different patients. The sequences of those two regions of the same genotype isolated from the same patient did not change with time. CONCLUSION: 5'-NCR is more conserved than the core region and the genotype is the major cause of gene variation. No change in sequences of those two regions is found at the different points of time.
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- Zhou, Qi, et al.
(författare)
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Miscibility, free volume behavior and properties of blends from cellulose acetate and castor oil-based polyurethane
- 2003
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Ingår i: Polymer. - 0032-3861 .- 1873-2291. ; 44:5, s. 1733-1739
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Tidskriftsartikel (refereegranskat)abstract
- A series of blend films from cellulose acetate (CA) and castor oil-based polyurethane (PU) were prepared. Morphology, miscibility, free volume behavior and properties of such blend films were investigated by wide-angle X-ray diffraction (WXRD), infrared, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), positron annihilation lifetime spectroscopy (PALS), thermogravimetric analysis and tensile test. The results indicated that lager free volume cavities did not form at the interface of two polymers although a certain degree of phase separation was found by the studies of SEM and DSC. Strong intermolecular hydrogen bonding interactions at the interface, which was proved by Fourier transform infrared spectroscopy, favors even better molecular packing, that is, PU dispersed in CA continuous phase to form fine microphase separation domain in the CA-rich blends. Due to such special interactions in the fine microphase separation domain structure, optimized properties of tensile strength, breaking elongation and cold-resistivity were obtained in the blend film with 75 wt% CA. The toughness of all the blend films was significantly higher than that of the film CA, owing to the plasticizing of PU elastomer in the blends.
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