| 1. |
- Abel, I, et al.
(author)
-
Overview of the JET results with the ITER-like wall
- 2013
-
In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
-
Journal article (peer-reviewed)abstract
- Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Z(eff) (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H-98,H-y2 close to 1 and beta(N) similar to 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.
|
|
| 2. |
- Romanelli, F, et al.
(author)
-
Overview of the JET results
- 2011
-
In: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 51:9
-
Journal article (peer-reviewed)abstract
- Since the last IAEA Conference JET has been in operation for one year with a programmatic focus on the qualification of ITER operating scenarios, the consolidation of ITER design choices and preparation for plasma operation with the ITER-like wall presently being installed in JET. Good progress has been achieved, including stationary ELMy H-mode operation at 4.5 MA. The high confinement hybrid scenario has been extended to high triangularity, lower ρ*and to pulse lengths comparable to the resistive time. The steady-state scenario has also been extended to lower ρ*and ν*and optimized to simultaneously achieve, under stationary conditions, ITER-like values of all other relevant normalized parameters. A dedicated helium campaign has allowed key aspects of plasma control and H-mode operation for the ITER non-activated phase to be evaluated. Effective sawtooth control by fast ions has been demonstrated with3He minority ICRH, a scenario with negligible minority current drive. Edge localized mode (ELM) control studies using external n = 1 and n = 2 perturbation fields have found a resonance effect in ELM frequency for specific q95values. Complete ELM suppression has, however, not been observed, even with an edge Chirikov parameter larger than 1. Pellet ELM pacing has been demonstrated and the minimum pellet size needed to trigger an ELM has been estimated. For both natural and mitigated ELMs a broadening of the divertor ELM-wetted area with increasing ELM size has been found. In disruption studies with massive gas injection up to 50% of the thermal energy could be radiated before, and 20% during, the thermal quench. Halo currents could be reduced by 60% and, using argon/deuterium and neon/deuterium gas mixtures, runaway electron generation could be avoided. Most objectives of the ITER-like ICRH antenna have been demonstrated; matching with closely packed straps, ELM resilience, scattering matrix arc detection and operation at high power density (6.2 MW m-2) and antenna strap voltages (42 kV). Coupling measurements are in very good agreement with TOPICA modelling. © 2011 IAEA, Vienna.
|
|
| 3. |
- Gould, A., et al.
(author)
-
MOA-2010-BLG-523:" Failed Planet"= RS CVn Star
- 2013
-
In: Astrophysical Journal. - 0004-637X. ; 763:2
-
Journal article (peer-reviewed)abstract
- The Galactic bulge source MOA-2010-BLG-523S exhibited short-term deviations from a standard microlensing light curve near the peak of an A(max) similar to 265 high-magnification microlensing event. The deviations originally seemed consistent with expectations for a planetary companion to the principal lens. We combine long-term photometric monitoring with a previously published high-resolution spectrum taken near peak to demonstrate that this is an RS CVn variable, so that planetary microlensing is not required to explain the light-curve deviations. This is the first spectroscopically confirmed RS CVn star discovered in the Galactic bulge.
|
|
| 4. |
- Puckett, A. J. R., et al.
(author)
-
Final analysis of proton form factor ratio data at Q(2)=4.0, 4.8, and 5.6 GeV2
- 2012
-
In: Physical Review C (Nuclear Physics). - 0556-2813. ; 85:4
-
Journal article (peer-reviewed)abstract
- Precise measurements of the proton electromagnetic form factor ratio R = mu(p)G(E)(p)/G(M)(p) using the polarization transfer method at Jefferson Lab have revolutionized the understanding of nucleon structure by revealing the strong decrease of R with momentum transfer Q(2) for Q(2) greater than or similar to 1 GeV2, in strong disagreement with previous extractions of R from cross-section measurements. In particular, the polarization transfer results have exposed the limits of applicability of the one-photon-exchange approximation and highlighted the role of quark orbital angular momentum in the nucleon structure. The GEp-II experiment in Jefferson Lab's Hall A measured R at four Q(2) values in the range 3.5 GeV2 <= Q(2) <= 5.6 GeV2. A possible discrepancy between the originally published GEp-II results and more recent measurements at higher Q(2) motivated a new analysis of the GEp-II data. This article presents the final results of the GEp-II experiment, including details of the new analysis, an expanded description of the apparatus, and an overview of theoretical progress since the original publication. The key result of the final analysis is a systematic increase in the results for R, improving the consistency of the polarization transfer data in the high-Q(2) region. This increase is the result of an improved selection of elastic events which largely removes the systematic effect of the inelastic contamination, underestimated by the original analysis.
|
|
| 5. |
- Giroud, C., et al.
(author)
-
Impact of nitrogen seeding on confinement and power load control of a high-triangularity JET ELMy H-mode plasma with a metal wall
- 2013
-
In: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 53:11, s. 113025-
-
Journal article (peer-reviewed)abstract
- This paper reports the impact on confinement and power load of the high-shape 2.5MA ELMy H-mode scenario at JET of a change from all carbon plasma-facing components to an all metal wall. In preparation to this change, systematic studies of power load reduction and impact on confinement as a result of fuelling in combination with nitrogen seeding were carried out in JET-C and are compared with their counterpart in JET with a metallic wall. An unexpected and significant change is reported on the decrease in the pedestal confinement but is partially recovered with the injection of nitrogen.
|
|
| 6. |
- Giroud, C., et al.
(author)
-
Integration of a radiative divertor for heat load control into JET high triangularity ELMy H-mode plasmas
- 2012
-
In: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 52:6, s. 063022-
-
Journal article (peer-reviewed)abstract
- Experiments on JET with a carbon-fibre composite wall have explored the reduction of steady-state power load in an ELMy H-mode scenario at high Greenwald fraction similar to 0.8, constant power and close to the L to H transition. This paper reports a systematic study of power load reduction due to the effect of fuelling in combination with seeding over a wide range of pedestal density ((4-8) x 10(19) m(-3)) with detailed documentation of divertor, pedestal and main plasma conditions, as well as a comparative study of two extrinsic impurity nitrogen and neon. It also reports the impact of steady-state power load reduction on the overall plasma behaviour, as well as possible control parameters to increase fuel purity. Conditions from attached to fully detached divertor were obtained during this study. These experiments provide reference plasmas for comparison with a future JET Be first wall and an all W divertor where the power load reduction is mandatory for operation.
|
|
| 7. |
- Maddison, G. P., et al.
(author)
-
Contrasting H-mode behaviour with deuterium fuelling and nitrogen seeding in the all-carbon and metallic versions of JET
- 2014
-
In: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 54:7, s. 073016-
-
Journal article (peer-reviewed)abstract
- The former all-carbon wall on JET has been replaced with beryllium in the main torus and tungsten in the divertor to mimic the surface materials envisaged for ITER. Comparisons are presented between type I H-mode characteristics in each design by examining respective scans over deuterium fuelling and impurity seeding, required to ameliorate exhaust loads both in JET at full capability and in ITER. Attention is focused upon a common high-triangularity, single-null divertor configuration at 2.5 MA, q(95) approximate to 3.5 yielding the most robust all-C performance. Contrasting results between the alternative linings are found firstly in unseeded plasmas, for which purity is improved and intrinsic radiation reduced in the ITER-like wall (ILW) but normalized energy confinement is approximate to 30% lower than in all-C counterparts, owing to a commensurately lower (electron) pedestal temperature. Divertor recycling is also radically altered, with slower, inboard-outboard asymmetric transients at ELMs and spontaneous oscillations in between them. Secondly, nitrogen seeding elicits opposite responses in the ILW to all-C experience, tending to raise plasma density, reduce ELM frequency, and above all to recover (electron) pedestal pressure, hence global confinement, almost back to previous levels. A hitherto unrecognized role of light impurities in pedestal stability and dynamics is consequently suggested. Thirdly, while heat loads on the divertor outboard target between ELMs are successfully reduced in proportion to the radiative cooling and ELM frequency effects of N in both wall environments, more surprisingly, average power ejected by ELMs also declines in the same proportion for the ILW. Detachment between transients is simultaneously promoted. Finally, inter-ELM W sources in the ILW divertor tend to fall with N input, although core accumulation possibly due to increased particle confinement still leads to significantly less steady conditions than in all-C plasmas. This limitation of ILW H-modes so far will be readdressed in future campaigns to continue progress towards a fully integrated scenario suitable for D-T experiments on JET and for 'baseline' operation on ITER. The diverse changes in behaviour between all-C and ILW contexts demonstrate essentially the strong impact which boundary conditions and intrinsic impurities can have on tokamak-plasma states.
|
|
| 8. |
- Wilson, S. K., et al.
(author)
-
Crucial knowledge gaps in current understanding of climate change impacts on coral reef fishes
- 2010
-
In: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 213:6, s. 894-900
-
Journal article (peer-reviewed)abstract
- Expert opinion was canvassed to identify crucial knowledge gaps in current understanding of climate change impacts on coral reef fishes. Scientists that had published three or more papers on the effects of climate and environmental factors on reef fishes were invited to submit five questions that, if addressed, would improve our understanding of climate change effects on coral reef fishes. Thirty-three scientists provided 155 questions, and 32 scientists scored these questions in terms of: (i) identifying a knowledge gap, (ii) achievability, (iii) applicability to a broad spectrum of species and reef habitats, and (iv) priority. Forty-two per cent of the questions related to habitat associations and community dynamics of fish, reflecting the established effects and immediate concern relating to climate-induced coral loss and habitat degradation. However, there were also questions on fish demographics, physiology, behaviour and management, all of which could be potentially affected by climate change. Irrespective of their individual expertise and background, scientists scored questions from different topics similarly, suggesting limited bias and recognition of a need for greater interdisciplinary and collaborative research. Presented here are the 53 highest-scoring unique questions. These questions should act as a guide for future research, providing a basis for better assessment and management of climate change impacts on coral reefs and associated fish communities.
|
|
| 9. |
|
|
| 10. |
- Brezinsek, S., et al.
(author)
-
Overview of experimental preparation for the ITER-Like Wall at JET
- 2011
-
In: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115 .- 1873-4820. ; 415:1, s. S936-S942
-
Journal article (peer-reviewed)abstract
- Experiments in JET with carbon-based plasma-facing components have been carried out in preparation of the ITER-Like Wall with beryllium main chamber and full tungsten divertor. The preparatory work was twofold: (i) development of techniques, which ensure safe operation with the new wall and (ii) provision of reference plasmas, which allow a comparison of operation with carbon and metallic wall. (i) Compatibility with the W divertor with respect to energy loads could be achieved in N-2 seeded plasmas at high densities and low temperatures, finally approaching partial detachment, with only moderate confinement reduction of 10%. Strike-point sweeping increases the operational space further by re-distributing the load over several components. (ii) Be and C migration to the divertor has been documented with spectroscopy and QMBs under different plasma conditions providing a database which will allow a comparison of the material transport to remote areas with metallic walls. Fuel retention rates of 1.0-2.0 x 10(21) D s(-1) were obtained as references in accompanied gas balance studies.
|
|
| 11. |
|
|
| 12. |
|
|
| 13. |
- Stefansson, S. O., et al.
(author)
-
Growth, osmoregulation and endocrine changes in wild Atlantic salmon smolts and post-smolts during marine migration
- 2012
-
In: Aquaculture. - : Elsevier BV. - 0044-8486. ; 362, s. 127-136
-
Journal article (peer-reviewed)abstract
- We have examined physiological parameters associated with seawater adaptability, growth and energetics, as well as major endocrine regulators of these processes in wild migrating Atlantic salmon smolts and post-smolts from the river through the fjord, coastal areas and the open ocean. Muscle RNA/DNA ratio suggests that growth rate increases soon after entry into seawater and continues to increase after the post-smolts reach the offshore banks and the feeding grounds in the Norwegian Sea. Post-smolts prioritize rapid growth and protein deposition in spring and summer, and their energy intake during this period is so high that deposition of energy is possible in addition to muscle growth. An increase in thyroxine (T-4) and triiodothyronine (T-3) levels was observed, suggesting a major activation of hepatic conversion of T-4 to T-3 in post-smolts in seawater, probably related to the high metabolic activity and rapid growth and development of the post-smolts. Decreased plasma growth hormone (GH) levels were observed from the river through the fjord, with levels around 2 ng ml(-1) in rapidly growing post-smolts, concurrent with an increase in circulating insulin-like growth factor I (IGF-I). An increase in pituitary GH expression levels and hepatic GH receptor (GH-R) and local IGF-I mRNA levels suggest a physiological basis for the changes in circulating GH and IGF-I levels. Receptor expression in brain and pituitary suggests that both hormones are actively involved in the growth and differentiation of these tissues during the critical early marine phase. Gill Na+, K+-ATPase (NKA) activity increased to post-smolt levels above 20 mu mol ADP mg prot.(divided by 1) h(divided by 1), probably representing long-term NKA activity levels of Atlantic salmon in seawater. Concurrent with the changes in NKA activity the expression of the NKA alpha 1b isoform remained high in post-smolts, while the expression of the NKA alpha 1a decreased from smolts to post-smolts. Both cystic fibrosis transmembrane conductance regulator (CFTR) I and II showed a reduction in mRNA levels from smolts to post-smolts, and remained stable at low expression levels in seawater. (c) 2011 Elsevier B.V. All rights reserved.
|
|
| 14. |
- Sundh, Henrik, 1976, et al.
(author)
-
Development of intestinal ion-transporting mechanisms during smoltification and seawater acclimation in Atlantic salmon Salmo salar
- 2014
-
In: Journal of Fish Biology. - : Wiley. - 0022-1112. ; 85:4, s. 1227-1252
-
Journal article (peer-reviewed)abstract
- This study investigated the expression of ion transporters involved in intestinal fluid absorption and presents evidence for developmental changes in abundance and tissue distribution of these transporters during smoltification and seawater (SW) acclimation of Atlantic salmon Salmo salar. Emphasis was placed on Na+, K+-ATPase (NKA) and Na+, K+, Cl- co-transporter (NKCC) isoforms, at both transcriptional and protein levels, together with transcription of chloride channel genes. The nka alpha 1c was the dominant isoform at the transcript level in both proximal and distal intestines; also, it was the most abundant isoform expressed in the basolateral membrane of enterocytes in the proximal intestine. This isoform was also abundantly expressed in the distal intestine in the lower part of the mucosal folds. The protein expression of intestinal Nka alpha 1c increased during smoltification. Immunostaining was localized to the basal membrane of the enterocytes in freshwater (FW) fish, and re-distributed to a lateral position after SW entry. Two other Nka isoforms, alpha 1a and alpha 1b, were expressed in the intestine but were not regulated to the same extent during smoltification and subsequent SW transfer. Their localization in the intestinal wall indicates a house-keeping function in excitatory tissues. The absorptive form of the NKCC-like isoform (sub-apically located NKCC2 and/or Na+, Cl(-)co-transporter) increased during smoltification and further after SW transfer. The cellular distribution changed from a diffuse expression in the sub-apical regions during smoltification to clustering of the transporters closer to the apical membrane after entry to SW. Furthermore, transcript abundance indicates that the mechanisms necessary for exit of chloride ions across the basolateral membrane and into the lateral intercellular space are present in the form of one or more of three different chloride channels: cystic fibrosis transmembrane conductance regulator I and II and chloride channel 3.
|
|
| 15. |
|
|
| 16. |
- McCormick, S. D., et al.
(author)
-
Differential regulation of sodium-potassium pump isoforms during smolt development and seawater exposure of Atlantic salmon
- 2013
-
In: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 216:7, s. 1142-1151
-
Journal article (peer-reviewed)abstract
- Freshwater and seawater isoforms of the alpha subunit of Na+/K+-ATPase (NKA) have previously been identified in gill ionocytes of Atlantic salmon (Salmo salar). In the present study we examine the abundance and cellular localization of these isoforms during the parr–smolt transformation, a developmental process that is preparatory for seawater entry. The abundance of NKAα1a was lower in smolts than in parr, remained relatively constant during spring and decreased in summer. NKAα1b increased tenfold in smolts during spring, peaking in late April, coincident with downstream migration and increased salinity tolerance. NKAα1b increased a further twofold after seawater exposure of smolts, whereas NKAα1a decreased by 98%. The abundance of NKAα1b-positive, and NKAα1b and NKAα1a co-labeled ionocytes increased during smolt development, whereas the number of NKAα1a cells decreased. After seawater exposure of smolts, NKAα1b-positive ionocytes increased, NKAα1a-positive cells decreased, and co-labeled cells disappeared. Plasma growth hormone and cortisol increased during spring in smolts, but not in parr, peaking just prior to the highest levels of NKAα1b. The results indicate that the increase in the abundance of NKAα1b during smolt development is directly linked to the increase in salinity tolerance that occurs at this stage, but that significant changes also occur after seawater exposure. Spring increases in circulating levels of growth hormone and cortisol indicate that these hormones may be instrumental in upregulating NKAα1b during smolt development.
|
|
| 17. |
- McCormick, S. D., et al.
(author)
-
Physiological and endocrine changes in Atlantic salmon smolts during hatchery rearing, downstream migration, and ocean entry
- 2013
-
In: Canadian Journal of Fisheries and Aquatic Sciences. - : Canadian Science Publishing. - 0706-652X .- 1205-7533. ; 70:1, s. 105-118
-
Journal article (peer-reviewed)abstract
- Billions of hatchery salmon smolts are released annually in an attempt to mitigate anthropogenic impacts on freshwater habitats, often with limited success. Mortality of wild and hatchery fish is high during downstream and early ocean migration. To understand changes that occur during migration, we examined physiological and endocrine changes in Atlantic salmon (Salmo salar) smolts during hatchery rearing, downstream migration, and early ocean entry in two successive years. Gill Na+/K+-ATPase activity increased in the hatchery during spring, increased further after river release, and was slightly lower after recapture in the ocean. Plasma growth hormone levels increased in the hatchery, were higher in the river, and increased further in the ocean. Plasma IGF-I remained relatively constant in the hatchery, increased in the river, then decreased in the ocean. Plasma thyroid hormones were variable in the hatchery, but increased in both river- and ocean-captured smolts. Naturally reared fish had lower condition factor, gill NKA activity, and plasma thyroxine than hatchery fish in the river but were similar in the ocean. This novel data set provides a vital first step in understanding the role and norms of endocrine function in smolts and the metrics of successful marine entry.
|
|
| 18. |
- Trencher, G., et al.
(author)
-
Beyond the Third Mission: Exploring the Emerging University Function of Co-creation for Sustainability
- 2014
-
In: Science and Public Policy. - : Oxford University Press (OUP). - 1471-5430 .- 0302-3427. ; 41:2, s. 151-179
-
Journal article (peer-reviewed)abstract
- This paper explores a global trend where universities are collaborating with local government, industry and civic organisations to advance the sustainable transformation of a specific town, city or region. With empirical evidence, we argue that this function of ‘cocreation for sustainability’ could be interpreted as the seeds of an emerging, new mission for the university. We demonstrate that this still evolving mission differs significantly to the economic focus of the third mission and conventional technology transfer practices, which we argue, should be critically examined. After defining five channels through which a university can fulfil the emerging mission, we analyse two frontrunner ‘transformative institutions’ engaged in co-creating social transformations in pursuit of materialising sustainable development in specific locations and regions. This study seeks to add to the debate on the third mission and triple-helix partnerships. It does so by incorporating sustainable development and place-based co-creation with government, industry and civil society.
|
|
