Investing in adaptations to rare events. A reproductive strategy

The occurrence of apparently unused organs and mechanisms related to reproduction has been described in various plants. A hypothesis is presented, suggesting that such structures will be retained if involved, even very rarely, in reproductive events with important evolutionary consequences. Two such cases are demonstrated: In the heterocarpous Caléndula arvensis, cross-pollination, which is very rare, can occur only in the most peripheral among the ray florets. These florets, whether self-or cross-pollinated, always form the largest achenes with the most elaborate adaptations for dispersal and the largest embryos. Flowers of Medicago polymorpha were shown to be self-pollinated previous to anthesis and their unused «explosive» tripping mechanism seems superfluous. However, at least in one region where this species is naturalized, a high percentage of outbreeding was observed. Selection for increased outbreeding during colonization and habitat dependent regulation of the breeding system are proposed as possible explanations. It is suggested that investing in adaptations to rare reproductive events with far reaching cónsequences may be a rather widespread reproductive strategy.Se ha descrito en varias plantas la existencia de órganos y mecanismos aparentemente inútiles relacionados con la reproducción. Se presenta una hipótesis por la que se sugiere que cuando se presentan, aunque sea muy rara vez, estas estructuras se mantienen en situación en que la reproducción tiene consecuencias evolutivas importantes. Se muestran dos de estos casos. En Calendula arvensis, que presenta heterocarpia, la polinización cruzada, que es muy rara, puede tener lugar sólo en las flores liguladas más externas. Estas flores, sea por autógamia o por alogamia, forman siempre los aquenios más largos que son los que presentan una mejor adaptación para la dispersion y los embriones más grandes. En Medicago polymorpha, las flores se autopolinizan antes de la antesis, por lo que parece superfluo su excepcional mecanismo de apertura explosivo. Sin embargo, al menos en una región en que esta especie se encuentra naturalizada, se ha observado un alto porcentaje de alogamia. Se propone para explicarlo la influencia de la selección para aumentar la alogamia durante la colonización y la regulación del sistema de reproducción por factores ambientales. Se sugiere que la utilización de sistemas reproductores especiales con consecuencias de largo alcance puede ser una estrategia reproductora bastante extendida

Overview of physics studies on ASDEX Upgrade

Abstract The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heating power, flexible heating mix and comprehensive diagnostic set allows studies ranging from mimicking the scrape-off-layer and divertor conditions of ITER and DEMO at high density to fully non-inductive operation (q 95  =  5.5, ) at low density. Higher installed electron cyclotron resonance heating power   6 MW, new diagnostics and improved analysis techniques have further enhanced the capabilities of AUG. Stable high-density H-modes with MW m−1 with fully detached strike-points have been demonstrated. The ballooning instability close to the separatrix has been identified as a potential cause leading to the H-mode density limit and is also found to play an important role for the access to small edge-localized modes (ELMs). Density limit disruptions have been successfully avoided using a path-oriented approach to disruption handling and progress has been made in understanding the dissipation and avoidance of runaway electron beams. ELM suppression with resonant magnetic perturbations is now routinely achieved reaching transiently . This gives new insight into the field penetration physics, in particular with respect to plasma flows. Modelling agrees well with plasma response measurements and a helically localised ballooning structure observed prior to the ELM is evidence for the changed edge stability due to the magnetic perturbations. The impact of 3D perturbations on heat load patterns and fast-ion losses have been further elaborated. Progress has also been made in understanding the ELM cycle itself. Here, new fast measurements of and E r allow for inter ELM transport analysis confirming that E r is dominated by the diamagnetic term even for fast timescales. New analysis techniques allow detailed comparison of the ELM crash and are in good agreement with nonlinear MHD modelling. The observation of accelerated ions during the ELM crash can be seen as evidence for the reconnection during the ELM. As type-I ELMs (even mitigated) are likely not a viable operational regime in DEMO studies of ‘natural’ no ELM regimes have been extended. Stable I-modes up to have been characterised using -feedback. Core physics has been advanced by more detailed characterisation of the turbulence with new measurements such as the eddy tilt angle—measured for the first time—or the cross-phase angle of and fluctuations. These new data put strong constraints on gyro-kinetic turbulence modelling. In addition, carefully executed studies in different main species (H, D and He) and with different heating mixes highlight the importance of the collisional energy exchange for interpreting energy confinement. A new regime with a hollow profile now gives access to regimes mimicking aspects of burning plasma conditions and lead to nonlinear interactions of energetic particle modes despite the sub-Alfvénic beam energy. This will help to validate the fast-ion codes for predicting ITER and DEMO.</jats:p

Real-time-capable prediction of temperature and density profiles in a tokamak using RAPTOR and a first-principle-based transport model

The RAPTOR code is a control-oriented core plasma profile simulator with various applications in control design and verification, discharge optimization and real-time plasma simulation. To date, RAPTOR was capable of simulating the evolution of poloidal flux and electron temperature using empirical transport models, and required the user to input assumptions on the other profiles and plasma parameters. We present an extension of the code to simulate the temperature evolution of both ions and electrons, as well as the particle density transport. A proof-of-principle neural-network emulation of the quasilinear gyrokinetic QuaLiKiz transport model is coupled to RAPTOR for the calculation of first-principle-based heat and particle turbulent transport. These extended capabilities are demonstrated in a simulation of a JET discharge. The multi-channel simulation requires ∼0.2 s to simulate 1 second of a JET plasma, corresponding to ∼20 energy confinement times, while predicting experimental profiles within the limits of the transport model. The transport model requires no external inputs except for the boundary condition at the top of the H-mode pedestal. This marks the first time that simultaneous, accurate predictions of Te, Tiand nehave been obtained using a first-principle-based transport code that can run in faster-than-real-time for present-day tokamaks