Repaired tetralogy of Fallot: the roles of cardiovascular magnetic resonance in evaluating pathophysiology and for pulmonary valve replacement decision support

Surgical management of tetralogy of Fallot (TOF) results in anatomic and functional abnormalities in the majority of patients. Although right ventricular volume load due to severe pulmonary regurgitation can be tolerated for many years, there is now evidence that the compensatory mechanisms of the right ventricular myocardium ultimately fail and that if the volume load is not eliminated or reduced by pulmonary valve replacement the dysfunction might be irreversible. Cardiovascular magnetic resonance (CMR) has evolved during the last 2 decades as the reference standard imaging modality to assess the anatomic and functional sequelae in patients with repaired TOF. This article reviews the pathophysiology of chronic right ventricular volume load after TOF repair and the risks and benefits of pulmonary valve replacement. The CMR techniques used to comprehensively evaluate the patient with repaired TOF are reviewed and the role of CMR in supporting clinical decisions regarding pulmonary valve replacement is discussed

The PLATO 2.0 mission

PLATO 2.0 has recently been selected for ESA's M3 launch opportunity (2022/24). Providing accurate key planet parameters (radius, mass, density and age) in statistical numbers, it addresses fundamental questions such as: How do planetary systems form and evolve? Are there other systems with planets like ours, including potentially habitable planets? The PLATO 2.0 instrument consists of 34 small aperture telescopes (32 with 25 s readout cadence and 2 with 2.5 s candence) providing a wide field-of-view (2232 deg 2) and a large photometric magnitude range (4-16 mag). It focusses on bright (4-11 mag) stars in wide fields to detect and characterize planets down to Earth-size by photometric transits, whose masses can then be determined by ground-based radial-velocity follow-up measurements. Asteroseismology will be performed for these bright stars to obtain highly accurate stellar parameters, including masses and ages. The combination of bright targets and asteroseismology results in high accuracy for the bulk planet parameters: 2 %, 4-10 % and 10 % for planet radii, masses and ages, respectively. The planned baseline observing strategy includes two long pointings (2-3 years) to detect and bulk characterize planets reaching into the habitable zone (HZ) of solar-like stars and an additional step-and-stare phase to cover in total about 50 % of the sky. PLATO 2.0 will observe up to 1,000,000 stars and detect and characterize hundreds of small planets, and thousands of planets in the Neptune to gas giant regime out to the HZ. It will therefore provide the first large-scale catalogue of bulk characterized planets with accurate radii, masses, mean densities and ages. This catalogue will include terrestrial planets at intermediate orbital distances, where surface temperatures are moderate. Coverage of this parameter range with statistical numbers of bulk characterized planets is unique to PLATO 2.0. The PLATO 2.0 catalogue allows us to e.g.: - complete our knowledge of planet diversity for low-mass objects, - correlate the planet mean density-orbital distance distribution with predictions from planet formation theories,- constrain the influence of planet migration and scattering on the architecture of multiple systems, and - specify how planet and system parameters change with host star characteristics, such as type, metallicity and age. The catalogue will allow us to study planets and planetary systems at different evolutionary phases. It will further provide a census for small, low-mass planets. This will serve to identify objects which retained their primordial hydrogen atmosphere and in general the typical characteristics of planets in such low-mass, low-density range. Planets detected by PLATO 2.0 will orbit bright stars and many of them will be targets for future atmosphere spectroscopy exploring their atmosphere. Furthermore, the mission has the potential to detect exomoons, planetary rings, binary and Trojan planets. The planetary science possible with PLATO 2.0 is complemented by its impact on stellar and galactic science via asteroseismology as well as light curves of all kinds of variable stars, together with observations of stellar clusters of different ages. This will allow us to improve stellar models and study stellar activity. A large number of well-known ages from red giant stars will probe the structure and evolution of our Galaxy. Asteroseismic ages of bright stars for different phases of stellar evolution allow calibrating stellar age-rotation relationships. Together with the results of ESA's Gaia mission, the results of PLATO 2.0 will provide a huge legacy to planetary, stellar and galactic science

Meltspun permanent magnet materials containing Fe\u3csub\u3e3\u3c/sub\u3eB as the main phase

\u3cp\u3eA novel type of permanent magnet material was obtained by annealing amorphous melt spun flakes of the approximate composition Nd\u3csub\u3e4\u3c/sub\u3eFe\u3csub\u3e78\u3c/sub\u3eB\u3csub\u3e18\u3c/sub\u3e. The annealing process consists of two steps. At first, at a temperature T\u3csub\u3e1\u3c/sub\u3e, the metastable compound Fe\u3csub\u3e3\u3c/sub\u3eB crystallizes while, at a higher temperature T\u3csub\u3e2\u3c/sub\u3e, the hard magnetic phase Nd\u3csub\u3e2\u3c/sub\u3eFe\u3csub\u3e14\u3c/sub\u3eB is formed. This phase comprises only 15% of the alloy. Nevertheless, materials in which the latter reaction has taken place show remarkable isotropic hard magnetic properties. The remanence μ\u3csub\u3e0\u3c/sub\u3eM\u3csub\u3er\u3c/sub\u3e is 1.2 T, while intrinsic coercive fields μ\u3csub\u3e0\u3c/sub\u3eH\u3csub\u3ec\u3c/sub\u3e of almost 0.4 T have been attained, with (BH)\u3csub\u3emax\u3c/sub\u3e=95 kJ/m\u3csup\u3e3\u3c/sup\u3e. In this paper the preparation of these materials, the compositional dependence of the magnetic properties and a possible explanation for the high isotropic remanence are presented.\u3c/p\u3

Structure and magnetic properties of R2Fe17Nx compounds

\u3cp\u3eWe have shown that ternary rare earth nitrides of the approximate composition R\u3csub\u3e2\u3c/sub\u3eFe\u3csub\u3e17\u3c/sub\u3eN\u3csub\u3e2.5\u3c/sub\u3e can be prepared by the reaction of R\u3csub\u3e2\u3c/sub\u3eFe\u3csub\u3e17\u3c/sub\u3e with nitrogen gas at 500°C for all members of this series. The crystal structure and lattice constants of these compounds have been determined and are discussed in terms of volume increase and nitrogen site occupation. The N\u3csub\u3e2\u3c/sub\u3e uptake was found to be accompanied by strong increases of the Curie temperature and room temperature magnetization. From the results it was derived that the N\u3csub\u3e2\u3c/sub\u3e uptake may lead to substantial changes in the RFe coupling strength.\u3c/p\u3