| 1. |
- Ongena, J., et al.
(författare)
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Recent progress on JET towards the ITER reference mode of operation at high density
- 2001
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Ingår i: Plasma Physics and Controlled Fusion. - 0741-3335 .- 1361-6587. ; 43, s. A11-A30
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Tidskriftsartikel (refereegranskat)abstract
- Recent progress towards obtaining high density and high confinement in JET as required for the ITER reference scenario at Q = 10 is summarized. Plasmas with simultaneous confinement H-98(y.2) = 1 and densities up to n/n(Gw) similar to 1 are now routinely obtained. This has been possible (i) by using plasmas at high (delta similar to 0.5) and medium (delta similar to 0.3-0.4) triangularity with sufficient heating power to maintain Type I ELMs, (ii) with impurity seeded plasmas at high (delta similar to 0.5) and low (delta less than or equal to 0.2) triangularity, (iii) with an optimized pellet injection sequence, maintaining the energy confinement and raising the density, and (iv) by carefully tuning the gas puff rate leading to plasmas with peaked density profiles and good confinement at long time scales. These high performance discharges exhibit Type I ELMs, with a new and more favourable behaviour observed at high densities, requiring further studies. Techniques for a possible mitigation of these ELMs are discussed, and first promising results are obtained with impurity seeding in discharges at high triangularity. Scaling studies using the new data of this year show a strong dependence of confinement on upper triangularity, density and proximity to the Greenwald limit. Observed MHD instabilities and methods to avoid these in high density and high confinement plasmas are discussed.
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| 2. |
- Coad, J. P., et al.
(författare)
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Erosion/deposition in JET during the period 1999-2001
- 2003
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Ingår i: Journal of Nuclear Materials. - 0022-3115 .- 1873-4820. ; 313, s. 419-423
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Tidskriftsartikel (refereegranskat)abstract
- Coated divertor and wall tiles exposed in JET for the 1999-2001 operations have been used to assess erosion/deposition. Deposited films of up to 90 mum thickness at the inner wall of the divertor tiles are, for the most part, enriched in beryllium and other metals, whilst carbon is probably chemically sputtered from these tiles and transported to shadowed regions of the inner divertor. However, from the composition at the surface of the tiles, it appears that the chemical erosion was 'switched off' by reducing the JET vessel wall temperature for the last part of the operations to 200 degreesC. Thick powdery deposits localised at the ion transport limit at each corner of the divertor may be due to physical sputtering. Erosion of the coatings is seen at the outer divertor wall, and on all the inner wall and outer limiter tiles.
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| 3. |
- Hillier, Ladeana W, et al.
(författare)
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Sequence and comparative analysis of the chicken genome provide unique perspectives on vertebrate evolution
- 2004
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 432:7018, s. 695-716
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Tidskriftsartikel (refereegranskat)abstract
- We present here a draft genome sequence of the red jungle fowl, Gallus gallus. Because the chicken is a modern descendant of the dinosaurs and the first non-mammalian amniote to have its genome sequenced, the draft sequence of its genome--composed of approximately one billion base pairs of sequence and an estimated 20,000-23,000 genes--provides a new perspective on vertebrate genome evolution, while also improving the annotation of mammalian genomes. For example, the evolutionary distance between chicken and human provides high specificity in detecting functional elements, both non-coding and coding. Notably, many conserved non-coding sequences are far from genes and cannot be assigned to defined functional classes. In coding regions the evolutionary dynamics of protein domains and orthologous groups illustrate processes that distinguish the lineages leading to birds and mammals. The distinctive properties of avian microchromosomes, together with the inferred patterns of conserved synteny, provide additional insights into vertebrate chromosome architecture.
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| 4. |
- Nordlander, Johan, et al.
(författare)
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Reactive objects
- 2002
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Ingår i: Fifth IEEE International Symposium on Object-Oriented Real-Time Distributed Computing. - Piscataway, NJ : IEEE Communications Society. ; , s. 155-158
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Konferensbidrag (refereegranskat)abstract
- Object-oriented, concurrent, and event-based programming models provide a natural framework in which to express the behavior of distributed and embedded software systems. However, contemporary programming languages still base their I/O primitives on a model in which the environment is assumed to be centrally controlled and synchronous, and interactions with the environment carried out through blocking subroutine calls. The gap between this view and the natural asynchrony of the real world has made event-based programming a complex and error-prone activity, despite recent focus on event-based frameworks and middleware. In this paper we present a consistent model of event-based concurrency, centered around the notion of reactive objects. This model relieves the object-oriented paradigm from the idea of transparent blocking, and naturally enforces reactivity and state consistency. We illustrate our point by a program example that offers substantial improvements in size and simplicity over a corresponding Java-based solution.
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| 5. |
- Rice, Ritva, et al.
(författare)
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Disruption of Fgf10/Fgfr2b-coordinated epithelial-mesenchymal interactions causes cleft palate.
- 2004
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Ingår i: Journal of Clinical Investigation. - 0021-9738. ; 113:12, s. 1692-1700
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Tidskriftsartikel (refereegranskat)abstract
- Classical research has suggested that early palate formation develops via epithelial-mesenchymal interactions, and in this study we reveal which signals control this process. Using Fgf10-/-, FGF receptor 2b-/- (Fgfr2b-/-), and Sonic hedgehog (Shh) mutant mice, which all exhibit cleft palate, we show that Shh is a downstream target of Fgf10/Fgfr2b signaling. Our results demonstrate that mesenchymal Fgf10 regulates the epithelial expression of Shh, which in turn signals back to the mesenchyme. This was confirmed by demonstrating that cell proliferation is decreased not only in the palatal epithelium but also in the mesenchyme of Fgfr2b-/- mice. These results reveal a new role for Fgf signaling in mammalian palate development. We show that coordinated epithelial-mesenchymal interactions are essential during the initial stages of palate development and require an Fgf-Shh signaling network.
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| 6. |
- Walpole, Andrew R., et al.
(författare)
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Nano-porous Alumina Coatings for Improved Bone Implant Interfaces
- 2003
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Ingår i: Materialwissenschaft und Werkstofftechnik. - : Wiley. - 0933-5137 .- 1521-4052. ; 34:12, s. 1064-1068
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Tidskriftsartikel (refereegranskat)abstract
- A new method is proposed for coating implants that produces a metal implant covered in a layer of nano-porous alumina ceramic. These layers are produced by first depositing a layer of aluminium on the implant surface and then anodising it in phosphoric acid to produce the nano-porous structure. This process results in the conversion of the aluminium to alumina containing 6-8wt% phosphate ions. The surface alumina layer is bonded to the substrate via an interfacial layer of fully dense anodised titanium oxide. Mechanical measurements have shown that the shear and tensile strength of this coating are in excess of 20MPa and 10MPa, respectively.The biological performance of nano-porous alumina material has been assessed and shown to be highly favourable, supporting normal osteoblastic activity and maintaining the osteoblastic phenotype. The filling of the nano-porous coating with bioactive material to achieve enhanced biological performance has been investigated using colloidal silica as an analogue for a Bioglass sol. The coating has been loaded with silica by dipping in colloidal silica with a pH of 5.6. Pore filling equivalent to 1.3 wt% SiO2 in the coating as a whole has been achieved in this way.
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| 7. |
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| 8. |
- Briggs, Ewan P, et al.
(författare)
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Formation of highly adherent nano-porous alumina on Ti-based substrates : a novel bone implant coating
- 2004
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Ingår i: Journal of materials science. Materials in medicine. - 0957-4530 .- 1573-4838. ; 15:9, s. 1021-1029
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Tidskriftsartikel (refereegranskat)abstract
- Thin, nano-porous, highly adherent layers of anodised aluminium formed on the surface of titanium alloys are being developed as coatings for metallic surgical implants. The layers are formed by anodisation of a 1–5 m thick layer of aluminium which has been deposited on substrate material by electron beam evaporation. The surface ceramic layer so produced is alumina with 6–8 wt % phosphate ions and contains 5×108 cm–2 pores with a 160 nm average diameter, running perpendicular to the surface. Mechanical testing showed the coatings'' shear and tensile strength to be at least 20 and 10 MPa, respectively. Initial cell/material studies show promising cellular response to the nano-porous alumina. A normal osteoblastic growth pattern with cell number increasing from day 1 to 21 was shown, with slightly higher proliferative activity on the nano-porous alumina compared to the Thermanox control. Scanning electron microscopy (SEM) examination of the cells on the porous alumina membrane showed normal osteoblast morphology. Flattened cells with filopodia attaching to the pores and good coverage were also observed. In addition, the pore structure produced in these ceramic coatings is expected to be suitable for loading with bioactive material to enhance further their biological properties.
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| 9. |
- Coutinho, Ana P, et al.
(författare)
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Induction of a parafacial rhythm generator by rhombomere 3 in the chick embryo.
- 2004
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Ingår i: Journal of Neuroscience. - 0270-6474 .- 1529-2401. ; 24:42, s. 9383-9390
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Tidskriftsartikel (refereegranskat)abstract
- Observations of knock-out mice suggest that breathing at birth requires correct development of a specific hindbrain territory corresponding to rhombomeres (r) 3 and 4. Focusing on this territory, we examined the development of a neuronal rhythm generator in the chick embryo. We show that rhythmic activity in r4 is inducible after developmental stage 10 through interaction with r3. Although the nature of this interaction remains obscure, we find that the expression of Krox20, a segmentation gene responsible for specifying r3 and r5, is sufficient to endow other rhombomeres with the capacity to induce rhythmic activity in r4. Induction is robust, because it can be reproduced with r2 and r6 instead of r4 and with any hindbrain territory that normally expresses Krox20 (r3, r5) or can be forced to do so (r1, r4). Interestingly, the interaction between r4 and r3/r5 that results in rhythm production can only take place through the anterior border of r4, revealing a heretofore unsuspected polarity in individual rhombomeres. The r4 rhythm generator appears to be homologous to a murine respiratory parafacial neuronal system developing in r4 under the control of Krox20 and Hoxa1. These results identify a late role for Krox20 at the onset of neurogenesis.
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| 10. |
- Dopson, Mark, et al.
(författare)
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Characterization of Ferroplasma isolates and Ferroplasma acidarmanus sp. nov., extreme acidophiles from acid mine drainage and industrial bioleaching environments.
- 2004
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Ingår i: Appl Environ Microbiol. - 0099-2240 .- 1098-5336. ; 70:4, s. 2079-88
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Tidskriftsartikel (refereegranskat)abstract
- Three recently isolated extremely acidophilic archaeal strains have been shown to be phylogenetically similar to Ferroplasma acidiphilum Y(T) by 16S rRNA gene sequencing. All four Ferroplasma isolates were capable of growing chemoorganotrophically on yeast extract or a range of sugars and chemomixotrophically on ferrous iron and yeast extract or sugars, and isolate "Ferroplasma acidarmanus" Fer1(T) required much higher levels of organic carbon. All four isolates were facultative anaerobes, coupling chemoorganotrophic growth on yeast extract to the reduction of ferric iron. The temperature optima for the four isolates were between 35 and 42 degrees C and the pH optima were 1.0 to 1.7, and "F. acidarmanus" Fer1(T) was capable of growing at pH 0. The optimum yeast extract concentration for "F. acidarmanus" Fer1(T) was higher than that for the other three isolates. Phenotypic results suggested that isolate "F. acidarmanus" Fer1(T) is of a different species than the other three strains, and 16S rRNA sequence data, DNA-DNA similarity values, and two-dimensional polyacrylamide gel electrophoresis protein profiles clearly showed that strains DR1, MT17, and Y(T) group as a single species. "F. acidarmanus" Fer1(T) groups separately, and we propose the new species "F. acidarmanus" Fer1(T) sp. nov.
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