| 1. |
- Broman, Göran, et al.
(författare)
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Introductory Optimisation Study of a Rammer Soil Compactor Machine
- 2001
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Konferensbidrag (refereegranskat)abstract
- Rammer compactor machines perform dynamic soil compaction. The complexity of this machine type makes design optimisation through traditional prototype testing impractical. This has pointed to the need for a theoretical model and simulation procedure for prediction of the dynamic behaviour of the machine and a procedure for optimisation as design parameters are changed during product development. In this paper a theoretical model of the rammer machine in combination with a soil model is described. This multi-body dynamics system is solved numerically. The system is non-linear and chaotic behaviour is possible. This parameter sensitivity emphasises the need for this kind of simulations in the product development process. A fairly regular behaviour is necessary for a predictable and safe operation. Parameter combinations giving too irregular behaviour are non-feasible. The energy transfer rate from the rammer machine into the soil is used as the objective function for optimisation. Multi-start Sequential Quadratic Programming for optimum search is used. To cover the design space well a Uniform Experimental Design is used for selection of starting points. This procedure proves to work well for the problem of this introductory study. The study shows a significant potential for improved compaction capacity although considering only the three design parameters that are most easily changed in practice. Approximately the same optimum is obtained both for operation on soft soil and hard soil, so a good all-round design seems possible. Including this theoretical support in the product development process should make it much more effective in finding optimum designs, also for other machines of similar type.
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| 2. |
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| 3. |
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| 4. |
- Englund, Anders
(författare)
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Trafiksäkerhet i fokus
- 2000
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Ingår i: VTI:s och KFB:s forskardagar. - Linköping : Statens väg- och transportforskningsinstitut. ; , s. 127-134
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 5. |
- Englund Johansson, Ulrica, et al.
(författare)
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In Vivo Properties of In Vitro-Propagated Neural Stem Cells After Transplantation to the Neonatal and Adult Rat Brain
- 2004
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Ingår i: Stem Cells in the Nervous System: Functional and Clinical Implications. Research and Perspectives in Neurosciences. - Berlin, Heidelberg : Springer. - 9783642623394 - 9783642188831
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Konferensbidrag (refereegranskat)abstract
- The ability to isolate neural stem and precursor cells and expand them in culture has provided researchers a new tool, not only assisting studies of neural development but also providing a new source of defined and expandable cells for in vivo studies using transplantation. The purposes of this chapter are, first, to review available protocols for in vitro expansion of neural precursor cells, either epigenetically using growth factors or genetically by inserting immortalizing genes; and, second, to discuss the in vivo properties of in vitro-propagated neural stem and progenitor cells, as assessed by grafting to the developing or adult rodent brain. This discussion will focus on our own recent studies using growth factor-expanded neurosphere cells of mouse and human origin and a particularly interesting, conditionally immortalized neural cell line, RN33B.
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| 6. |
- Englund Johansson, Ulrica, et al.
(författare)
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Migration patterns and phenotypic differentiation of long-term expanded human neural progenitor cells after transplantation into the adult rat brain.
- 2002
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Ingår i: Developmental Brain Research. - 0165-3806. ; 134:1-2, s. 123-141
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Tidskriftsartikel (refereegranskat)abstract
- We have examined long-term growth-factor expanded human neural progenitors following transplantation into the adult rat brain. Cells, obtained from the forebrain of a 9-week old fetus, propagated in the presence of epidermal growth factor, basic fibroblast growth factor, and leukemia inhibitory factor were transplanted into the striatum, subventricular zone (SVZ), and hippocampus. At 14 weeks, implanted cells were identified using antisera recognizing human nuclei and the reporter gene green fluorescent protein. Different migration patterns of the grafted cells were observed: (i) target-directed migration of doublecortin (DCX, a marker for migrating neuroblasts)-positive cells along the rostral migratory stream to the olfactory bulb and into the granular cell layer following transplantation into the SVZ and hippocampus, respectively; (ii) non-directed migration of DCX-positive cells in the grey matter in striatum and hippocampus, and (iii) extensive migration of above all nestin-positive/DCX-negative cells within white matter tracts. At the striatal implantation site, neuronal differentiation was most pronounced at the graft core with axonal projections extending along the internal capsule bundles. In the hippocampus, cells differentiated primarily into interneurons both in the dentate gyrus and in the CA1-3 regions as well as into granule-like neurons. In the striatum and hippocampus, a significant proportion of the grafted cells differentiated into glial cells, some with long processes extending along white matter tracts. Although the survival time was over 3 months in the present study a large fraction of the grafted cells remained undifferentiated in a stem or progenitor cell stage as revealed by the expression of nestin and/or GFAP.
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| 7. |
- Englund Johansson, Ulrica, et al.
(författare)
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Migration patterns and phenotypic differentiation of long-term expanded human neural progenitor cells after transplantation into the adult rat brain
- 2002
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Ingår i: Developmental Brain Research. - : Elsevier. - 0165-3806 .- 1872-6755. ; 134:1-2, s. 123-141
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Tidskriftsartikel (refereegranskat)abstract
- We have examined long-term growth-factor expanded human neural progenitors following transplantation into the adult rat brain. Cells, obtained from the forebrain of a 9-week old fetus, propagated in the presence of epidermal growth factor, basic fibroblast growth factor, and leukemia inhibitory factor were transplanted into the striatum, subventricular zone (SVZ), and hippocampus. At 14 weeks, implanted cells were identified using antisera recognizing human nuclei and the reporter gene green fluorescent protein. Different migration patterns of the grafted cells were observed: (i) target-directed migration of doublecortin (DCX, a marker for migrating neuroblasts)-positive cells along the rostral migratory stream to the olfactory bulb and into the granular cell layer following transplantation into the SVZ and hippocampus, respectively; (ii) non-directed migration of DCX-positive cells in the grey matter in striatum and hippocampus, and (iii) extensive migration of above all nestin-positive/DCX-negative cells within white matter tracts. At the striatal implantation site, neuronal differentiation was most pronounced at the graft core with axonal projections extending along the internal capsule bundles. In the hippocampus, cells differentiated primarily into interneurons both in the dentate gyrus and in the CA1-3 regions as well as into granule-like neurons. In the striatum and hippocampus, a significant proportion of the grafted cells differentiated into glial cells, some with long processes extending along white matter tracts. Although the survival time was over 3 months in the present study a large fraction of the grafted cells remained undifferentiated in a stem or progenitor cell stage as revealed by the expression of nestin and/or GFAP.
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| 8. |
- Englund Johansson, Ulrica, et al.
(författare)
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Transplantation of human neural progenitor cells into the neonatal rat brain: extensive migration and differentiation with long-distance axonal projections.
- 2002
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886 .- 1090-2430. ; 173:1, s. 1-21
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Tidskriftsartikel (refereegranskat)abstract
- Here we examined the ability of human neural progenitors from the embryonic forebrain, expanded for up to a year in culture in the presence of growth factors, to respond to environmental signals provided by the developing rat brain. After survival times of up to more than a year after transplantation into the striatum, the hippocampus, and the subventricular zone, the cells were analyzed using human-specific antisera and the reporter gene green fluorescent protein (GFP). From grafts implanted in the striatum, the cells migrated extensively, especially within white matter structures. Neuronal differentiation was most pronounced at the striatal graft core, with axonal projections extending caudally along the internal capsule into mesencephalon. In the hippocampus, cells migrated throughout the entire hippocampal formation and into adjacent white matter tracts, with differentiation into neurons both in the dentate gyrus and in the CA1-3 regions. Directed migration along the rostral migratory stream to the olfactory bulb and differentiation into granule cells were observed after implantation into the subventricular zone. Glial differentiation occurred at all three graft sites, predominantly at the injection sites, but also among the migrating cells. A lentiviral vector was used to transduce the cells with the GFP gene prior to grafting. The reporter gene was expressed for at least 15 weeks and the distribution of the gene product throughout the entire cytoplasmic compartment of the expressing cells allowed for a detailed morphological analysis of a portion of the grafted cells. The extensive integration and differentiation of in vitro-expanded human neural progenitor cells indicate that multipotent progenitors are capable of responding in a regionally specific manner to cues present in the developing rat brain.
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| 9. |
- Englund, Ulrica, et al.
(författare)
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Grafted neural stem cells develop into functional pyramidal neurons and integrate into host cortical circuitry.
- 2002
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 99:26, s. 17089-17094
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Tidskriftsartikel (refereegranskat)abstract
- In vitro expanded neural stem/progenitor cells can undergo region-specific differentiation after transplantation to the developing or adult brain, and display morphologies and markers characteristic of mature neurons. Here we have used patch-clamp techniques to explore whether grafted stem cells also can develop physiological properties of mature neurons and become functionally integrated within host neural circuitry. The immortalized neural progenitor cell line, RN33B, prelabeled with GFP by using a lentiviral vector, was transplanted into the cortex or hippocampus of neonatal rats. We found that the grafted GFP-positive cells differentiated into cells with morphological features of cortical or hippocampal pyramidal neurons, and that many of them had established appropriate cortico-thalamic and contralateral hippocampal connections, respectively, as revealed by retrograde tracing. Whole-cell patch-clamp recordings from grafted cells with morphological characteristics of pyramidal neurons showed that they were able to generate action potentials, and received functional excitatory and inhibitory synaptic inputs from neighboring cells. These data provide evidence that grafted neural progenitors can differentiate into morphologically mature pyramidal projection neurons, establish appropriate long-distance axonal projections, exhibit normal electrophysiological properties, and become functionally integrated into host cortical circuitry.
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| 10. |
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| 11. |
- Heins, Nico, et al.
(författare)
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Derivation, characterization, and differentiation of human embryonic stem cells.
- 2004
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Ingår i: Stem cells (Dayton, Ohio). - 1066-5099. ; 22:3, s. 367-76
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Tidskriftsartikel (refereegranskat)abstract
- The derivation of human embryonic stem (hES) cells establishes a new avenue to approach many issues in human biology and medicine for the first time. To meet the increased demand for characterized hES cell lines, we present the derivation and characterization of six hES cell lines. In addition to the previously described immunosurgery procedure, we were able to propagate the inner cell mass and establish hES cell lines from pronase-treated and hatched blastocysts. The cell lines were extensively characterized by expression analysis of markers characteristic for undifferentiated and differentiated hES cells, karyotyping, telomerase activity measurement, and pluripotency assays in vitro and in vivo. Whereas three of the cell lines expressed all the characteristics of undifferentiated pluripotent hES cells, one cell line carried a chromosome 13 trisomy while maintaining an undifferentiated pluripotent state, and two cell lines, one of which carried a triploid karyotype, exhibited limited pluripotency in vivo. Furthermore, we clonally derived one cell line, which could be propagated in an undifferentiated pluripotent state.
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| 12. |
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| 13. |
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| 14. |
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| 15. |
- Lundberg, Cecilia, et al.
(författare)
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Differentiation of the RN33B Cell Line into Forebrain Projection Neurons after Transplantation into the Neonatal Rat Brain.
- 2002
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Ingår i: Experimental Neurology. - : Elsevier BV. - 0014-4886 .- 1090-2430. ; 175:2, s. 370-387
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Tidskriftsartikel (refereegranskat)abstract
- The rat neural cell line RN33B has a remarkable ability to undergo region-specific neuronal differentiation after transplantation into the CNS. To further study its neurogenic properties in vivo, we used a recombinant lentiviral vector to genetically label the cells with the Green Fluorescent Protein (GFP) gene before implantation into the striatum/cortex, hippocampus, or mesencephalon of newborn rats. Three weeks after implantation, about 1-2% of the GFP-expressing cells had developed morphologies typical of neurons, astrocytes, or oligodendrocytes, the rest remained as either immature or undifferentiated nestin-positive cells. At 15-17 weeks postgrafting, the immature cells had disappeared in most graft recipients and only cells with neuronal or glial morphologies remained in similar numbers as at 3 weeks. The GFP distributed throughout the expressing cells, revealing fine morphological details, including dendrites with spines and extensive axonal projections. In all forebrain regions, the grafted cells differentiated into neurons with morphologies characteristic for each site, including large numbers of pyramidal-like cells in the cortex and the hippocampus, giving rise to dense projections to normal cortical target regions and to the contralateral hippocampus, respectively. In lower numbers, it was also possible to identify GFP-positive granulelike cells in the hippocampus, as well as densely spiny neurons in the striatum. In the mesencephalon by contrast, cells with astrocytic features predominated. The ability of the grafted RN33B cells to undergo region-specific differentiation into highly specialized types of forebrain projection neurons and establish connections with appropriate targets suggests that cues present in the microenvironment of the neonatal rat brain can effectively guide the development of immature progenitors, also in the absence of ongoing neurogenesis. (c) 2002 Elsevier Science (USA).
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| 16. |
- Svensson, Per Anders, 1959, et al.
(författare)
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Identification of genes predominantly expressed in human macrophages
- 2004
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Ingår i: Atherosclerosis. - : Elsevier BV. ; 177, s. 287-290
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Tidskriftsartikel (refereegranskat)abstract
- Identification of cell and tissue specific genes may provide novel insights to signaling systems and functions. Macrophages play a key role in many diseases including atherosclerosis. Using DNA microarrays we compared the expression of approximately 10,000 genes in 56 human tissues and identified 23 genes with predominant expression in macrophages. The identified genes include both genes known to be macrophage specific and genes previously not well described in this cell type. Tissue distribution of two genes, liver X receptor (LXR) alpha and interleukin-1 receptor antagonist (IL1RN), was verified by real-time RT-PCR. We conclude that comparison of expression profiles from a large number of tissues can be used to identify genes that are predominantly expressed in certain tissues. Identification of novel macrophage specific genes may increase our understanding of the role of this cell in different diseases.
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