| 1. |
- Weber, Toni M., et al.
(författare)
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Smear zone identification and soil properties around stone columns constructed in-flight in centrifuge model tests
- 2010
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Ingår i: Geotechnique. - 0016-8505 .- 1751-7656. ; 60:3, s. 197-206
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Tidskriftsartikel (refereegranskat)abstract
- Stone columns are primarily used for the purpose of ground improvement in fine grained soils in order to reduce settlements and the risk of bearing failure. They are also designed to improve the drainage conditions in the ground and to accelerate the consolidation processes within the clay. However, smear and disturbing effects caused during the construction of stone columns result in degradation of consolidation performance in comparison with the theoretically ideal conditions. Model stone columns are constructed in-flight under 50 times gravity in centrifuge tests and the soil micro-structure in the vicinity of these columns is investigated by applying different methods, including environmental scanning electron microscopy and mercury intrusion porosimetry. The results these tests confirm that smear and disturbance occur owing to stone column installation and the region influenced can be divided into three sections: a penetration zone (1) where the sand particles are squeezed through the clay; a smear zone (2) where the soil particles have experienced a significant reorientation; and a densification zone (3) where the structure of the clay does not appear to change, but compaction of the clay is measurable. The extremes of the disturbed zone around model stone columns are determined to extend to about 2.5 times the column radius.
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| 2. |
- Hu, Bin, et al.
(författare)
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Molecular characterization and immunohistochemical localization of palmdelphin, a cytosolic isoform of the paralemmin protein family implicated in membrane dynamics
- 2005
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Ingår i: European Journal of Cell Biology. - : Elsevier BV. - 0171-9335 .- 1618-1298. ; 84:11, s. 853-866
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Tidskriftsartikel (refereegranskat)abstract
- Palmdelphin is a newly identified cytosolic isoform of paratemmin-1, a lipid raft-associated protein implicated in cell shape control. Like paralemmin- 1,palmdelphin is phosphorylated, giving rise to electrophoretic band heterogeneity that is most pronounced in the brain. In ultracentrifugation and get filtration palmdelphin behaves as a non-globular monomer. Its C-terminal region binds glutamine synthetase. Immunohistochemical analysis of the rat brain shows a prominent localization of palmdelphin in the cerebral cortex, hippocampus, amygdala, septum, indusium griseum, piriform cortex, nucleus supraopticus, and nucleus of the lateral olfactory tract. Many of the circumscript palmdelphin-positive areas are related to the olfactory system. Immunoperoxidase electron microscopy reveals a discontinuous distribution of palmdelphin immunoreactivity, in the form of spots scattered throughout the cytoplasm of selected neuronal perikarya and dendrites, including dendritic spines, often in association with endomembranes, and in a pattern which is similar to that of the cytoplasmic fraction of paralemmin-1. In subcellular fractionation experiments palmdelphin behaves as a cytosolic protein which, however, can be partially recruited from cytosol to the detergent-resistant fraction of a membrane/cytoskeletal cell ghost preparation. These observations suggest that palmdelphin may peripherally associate with endomembranes or cytoskeleton-linked structures.
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| 3. |
- Kapogianni, Elena, et al.
(författare)
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Investigation of the Mechanical Behaviour of the Interface between Soil and Reinforcement, via Experimental and Numerical Modelling
- 2016
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Ingår i: Procedia Engineering. - : Elsevier BV. - 1877-7058. ; 143, s. 419-426
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this study is to investigate the interface properties between soil and reinforcement, via experimental and numerical modelling of reinforced slopes. In particular, several scale models were built and tested under enhanced gravity in the geotechnical drum centrifuge at ETH Zurich and corresponding prototype numerical models were analyzed via a finite element stress analysis code. Optical fibre sensors were attached on the reinforcement layers of the experimental scaled models in order to measure linear strain during the increase of the g-level, and the results were compared to linear strain that was derived by the numerical analysis of the correspondent prototype reinforced slopes. The interface between soil and reinforcement was expressed in terms of normal and shear stiffness on the soil-reinforcement boundary and different values were tested in order to achieve validation of the experimental and numerical results.
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| 4. |
- Kapogianni, Elena, et al.
(författare)
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The use of optical fibre sensors in a geotechnical centrifuge for reinforced slopes
- 2010
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Ingår i: Physical Modelling in Geotechnics. - 9780415592895 ; , s. 343-348
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Konferensbidrag (refereegranskat)abstract
- The purpose of this paper is to investigate making strain measurements via optical fibre sensors in a geotechnical centrifuge. This study is part of a test series, which has been carried out in the ETH Zurich geotechnical centrifuge, with the main goal being to investigate the behaviour of reinforced slopes that are subjected, initially, to self weight loading and, subsequently, to impact from a rockfall event. Several reinforced slope models were built with a height of 18 cm and a slope inclination of 2V:1H. The maximum g-level applied was 100 g and the optical fibre sensors were placed on the reinforcement layers at various positions in the model in order to measure the deformations of the reinforcement during the different loading events. © 2010 Taylor & Francis Group, London.
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| 5. |
- Laue, J., et al.
(författare)
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15 years of experience using a physical model exercise in a Masters' course
- 2014
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Ingår i: Physical modelling in geotechnics. - Leiden : CRC Press/Balkema. - 9781138022218 ; , s. 445-450
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Konferensbidrag (refereegranskat)abstract
- Modelling in Geotechnics' has been taught for two hours over 14 weeks in the 2nd, and later 3rd, semester of the Masters' studies at ETH Zurich. In addition to a series of frontal lectures on modelling techniques, as well as for their application to various boundary value problems, this course contains an exercise that compares 3 ways of modelling a practical case. Students are invited to investigate a common boundary value problem through complementary analytical, physical and numerical (finite element) modelling. A suitable boundary value problem, such as for shallow foundations or slopes, is selected to ensure that the exercise can be conducted in the limited time available for the students, and that the physical model takes only a finite amount of time so that all students can witness a test from start to finish. A comparison allows the assumptions made for the various models or calculations to be discussed and trains the students to put the different results into perspective. Practical aspects such as feasibility and timing, as well as applicability to reaching the learning goal of the class, will be reviewed. © 2010 Taylor & Francis Group, London.
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| 6. |
- Limbach, Christoph, et al.
(författare)
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Molecular in situ topology of Aczonin/Piccolo and associated proteins at the mammalian neurotransmitter release site
- 2011
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 108:31, s. E392-E401
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Tidskriftsartikel (refereegranskat)abstract
- The protein machinery of neurotransmitter exocytosis requires efficient orchestration in space and time, for speed and precision of neurotransmission and also for synaptic ontogeny and plasticity. However, its spatial organization in situ is virtually unknown. Aczonin/Piccolo is a putative organizer protein of mammalian active zones. We determined by immunogold electron microscopy (EM) (i) the spatial arrangement (i. e., topology) of 11 segments of the Aczonin polypeptide in situ, and correlated it to (ii) the positioning of Aczonin-interacting domains of Bassoon, CAST/ELKS, Munc13, and RIM and (iii) the ultrastructurally defined presynaptic macromolecular aggregates known as dense projections and synaptic ribbons. At conventional synapses, Aczonin assumes a compact molecular topology within a layer 35 to 80 nm parallel to the plasma membrane (PM), with a "trunk" sitting on the dense projection top and a C-terminal "arm" extending down toward the PM and sideward to the dense projection periphery. At ribbon synapses, Aczonin occupies the whole ribbon area. Bassoon colocalizes with Aczonin at conventional synapses but not at ribbon synapses. At both conventional and ribbon synapses, CAST, Munc13, and RIM are segregated from Aczonin, closer to the PM, and Aczonin is positioned such that it may control the access of neurotransmitter vesicles to the fusion site.
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| 7. |
- Opel, Michael, et al.
(författare)
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Genome-Wide Studies of Histone Demethylation Catalysed by the Fission Yeast Homologues of Mammalian LSD1
- 2007
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 2:4
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Tidskriftsartikel (refereegranskat)abstract
- In order to gain a more global view of the activity of histone demethylases, we report here genome-wide studies of the fission yeast SWIRM and polyamine oxidase (PAO) domain homologues of mammalian LSD1. Consistent with previous work we find that the two S. pombe proteins, which we name Swm1 and Swm2 (after SWIRM1 and SWIRM2), associate together in a complex. However, we find that this complex specifically demethylates lysine 9 in histone H3 (H3K9) and both up-and down-regulates expression of different groups of genes. Using chromatin-immunoprecipitation, to isolate fragments of chromatin containing either H3K4me2 or H3K9me2, and DNA microarray analysis (ChIP-chip), we have studied genome-wide changes in patterns of histone methylation, and their correlation with gene expression, upon deletion of the swm1(+) gene. Using hyper-geometric probability comparisons we uncover genetic links between lysine-specific demethylases, the histone deacetylase Clr6, and the chromatin remodeller Hrp1. The data presented here demonstrate that in fission yeast the SWIRM/PAO domain proteins Swm1 and Swm2 are associated in complexes that can remove methyl groups from lysine 9 methylated histone H3. In vitro, we show that bacterially expressed Swm1 also possesses lysine 9 demethylase activity. In vivo, loss of Swm1 increases the global levels of both H3K9me2 and H3K4me2. A significant accumulation of H3K4me2 is observed at genes that are up-regulated in a swm1 deletion strain. In addition, H3K9me2 accumulates at some genes known to be direct Swm1/2 targets that are down-regulated in the swm1 Delta strain. The in vivo data indicate that Swm1 acts in concert with the HDAC Clr6 and the chromatin remodeller Hrp1 to repress gene expression. In addition, our in vitro analyses suggest that the H3K9 demethylase activity requires an unidentified post-translational modification to allow it to act. Thus, our results highlight complex interactions between histone demethylase, deacetylase and chromatin remodelling activities in the regulation of gene expression.
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