| 1. |
- Monier-Garbet, P, et al.
(författare)
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Impurity-seeded ELMy H-modes in JET, with high density and reduced heat load
- 2005
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 45:11, s. 1404-1410
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Tidskriftsartikel (refereegranskat)abstract
- Experiments performed at JET during the past two years show that, in high triangularity H-mode plasmas with I-p = 2.5 MA, n(e)/n(Gr) approximate to 1.0, it is possible to radiate separately up to approximate to 40% of the total injected power on closed flux surfaces in the pedestal region (argon seeding) and up to approximate to 50% of the injected power in the divertor region (nitrogen seeding), while maintaining the confinement improvement factor at the value required for ITER, H98(y, 2) 1.0. The total radiated power fraction achieved in both cases (65-70%) is close to that required for ITER. However, Type I ELMS observed with impurity seeding have the same characteristics as that observed in reference pulses without seeding: decreasing plasma energy loss per ELM with increasing pedestal collisionality. One has to reach the Type III ELM regime to decrease the transient heat load to the divertor to acceptable values for ITER, although at the expense of confinement. The feasibility of an integrated scenario with Type-III ELMS, and q(95) = 2.6 to compensate for the low H factor, has been demonstrated on JET. This scenario would meet ITER requirements at 17 MA provided that the IPB98 scaling for energy content is accurate enough, and provided that a lower dilution is obtained when operating at higher absolute electron density.
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| 2. |
- Nene, Vishvanath, et al.
(författare)
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Genome sequence of Aedes aegypti, a major arbovirus vector.
- 2007
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Ingår i: Science (New York, N.Y.). - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 316:5832, s. 1718-23
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Tidskriftsartikel (refereegranskat)abstract
- We present a draft sequence of the genome of Aedes aegypti, the primary vector for yellow fever and dengue fever, which at approximately 1376 million base pairs is about 5 times the size of the genome of the malaria vector Anopheles gambiae. Nearly 50% of the Ae. aegypti genome consists of transposable elements. These contribute to a factor of approximately 4 to 6 increase in average gene length and in sizes of intergenic regions relative to An. gambiae and Drosophila melanogaster. Nonetheless, chromosomal synteny is generally maintained among all three insects, although conservation of orthologous gene order is higher (by a factor of approximately 2) between the mosquito species than between either of them and the fruit fly. An increase in genes encoding odorant binding, cytochrome P450, and cuticle domains relative to An. gambiae suggests that members of these protein families underpin some of the biological differences between the two mosquito species.
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| 3. |
- Kowalczyk, P., et al.
(författare)
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Two-parameter discontinuity-induced bifurcations of limit cycles : Classification and open problems
- 2006
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Ingår i: International Journal of Bifurcation and Chaos in Applied Sciences and Engineering. - 0218-1274. ; 16:3, s. 601-629
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a strategy for the classification of codimension-two discontinuity-induced bifurcations of limit cycles in piecewise smooth systems of ordinary differential equations. Such nonsmooth transitions (also known as C-bifurcations) occur when the cycle interacts with a discontinuity boundary of phase space in a nongeneric way, such as grazing contact. Several such codimension-one events have recently been identified, causing for example, period-adding or sudden onset of chaos. Here, the focus is on codimension-two grazings that are local in the sense that the dynamics can be fully described by an appropriate Poincare map from a neighborhood of the grazing point (or points) of the critical cycle to itself. It is proposed that codimension-two grazing bifurcations can be divided into three distinct types: either the grazing point is degenerate, or the grazing cycle is itself degenerate (e.g. nonhyperbolic) or we have the simultaneous occurrence of two grazing events. A careful distinction is drawn between their occurrence in systems with discontinuous states, discontinuous vector fields, or that with discontinuity in some derivative of the vector field. Examples of each kind of bifurcation are presented, mostly derived from mechanical applications. For each example, where possible, principal bifurcation curves characteristic to the codimension-two scenario are presented and general features of the dynamics discussed. Many avenues for future research are opened.
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| 4. |
- Loarer, T., et al.
(författare)
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Gas balance and fuel retention in fusion devices
- 2007
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 47:9, s. 1112-1120
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Tidskriftsartikel (refereegranskat)abstract
- The evaluation of hydrogenic retention in present tokamaks is of crucial importance to estimate the expected tritium (T) vessel inventory in ITER, limited from safety considerations to 350 g. In the framework of the European Task Force on Plasma Wall Interaction (EU TF on PWI) efforts are underway to investigate gas balance and fuel retention during discharges, and to compare the data obtained with those from post-mortem analysis of in-vessel components exposed over whole experimental campaigns. This paper summarizes the principal findings from coordinated studies on gas balance and fuel retention from a number of European tokamaks, namely, ASDEX-Upgrade (AUG), JET, TEXTOR and Tore Supra (TS). For most devices, the long-term retention fraction deduced from integrated particle balance is similar to 10-20%. This is larger than the similar to 3-4% deduced from post-mortem analysis of plasma facing components (PFCs). However, from the database available for tokamaks with their main PFCs made of carbon, the important conclusion is that the T inventory limit (set by the working guideline for operations) could be reached in ITER within fewer than 100 discharges. This, therefore, would seriously impact on operation of the device unless efficient T removal processes are developed.
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| 5. |
- Melin, M, et al.
(författare)
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Changes in the ST-interval segment of the fetal electrocardiogram in relation to acid-base status at birth.
- 2008
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Ingår i: BJOG: An International Journal of Obstetrics & Gynaecology. - : Wiley. - 1471-0528 .- 1470-0328. ; 115:13, s. 1669-1675
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Tidskriftsartikel (refereegranskat)abstract
- Objective To assess the occurrence of ST-interval segment changes of the fetal electrocardiogram (ECG) and cardiotocographic (CTG) abnormalities preceding acidaemia at birth. Design Case-control study. Setting University hospital labour ward. Sample Newborns with severe cord artery metabolic acidaemia (pH < 7.00 and lactate >/= 10 mmol/l; n= 24), moderate metabolic acidaemia (pH 7.00-7.09 and lactate >/= 10; n= 48), acidaemia (pH 7.00-7.09; n= 52), pre-acidaemia (pH 7.10-7.19; n= 265), and controls (pH >/= 7.20; n= 117). Methods Monitoring traces were assessed blinded to outcome. Main outcome measures CTG and ST changes. Results Any ST event occurred significantly more often among cases with severe (79%) and moderate (75%) metabolic acidaemia than among controls (50%). The difference was restricted to baseline T/QRS rises and to the second stage of labour, during which any event only occurred significantly more often among cases with severe metabolic acidaemia (62%) than among controls (38%). ST events coincided with abnormal CTG patterns in 67, 44, 40, and 28% of cases with severe and moderate metabolic acidaemia, acidaemia, and pre-acidaemia, respectively, and in 12% of controls. ST events with intermediary CTG were similarly frequent in the case groups (0-6%) as in the controls (4%). The ST guidelines stated intervention in 96, 62, 73, and 49% of case groups and 23% of controls. Conclusions Only two of three cases with severe and less than half of cases with moderate metabolic acidaemia were preceded by ST events coinciding with CTG abnormalities. It is therefore important to intervene for long-lasting, rapidly deteriorating or marked (preterminal) CTG abnormalities, also in the absence of ST events.
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| 6. |
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