MOBSTER – III. HD 62658: a magnetic Bp star in an eclipsing binary with a non-magnetic ‘identical twin’

HD 62658 (B9p V) is a little-studied chemically peculiar star. Light curves obtained by the Kilodegree Extremely Little Telescope (KELT) and Transiting Exoplanet Survey Satellite (TESS) show clear eclipses with a period of about 4.75 d, as well as out-of-eclipse brightness modulation with the same 4.75 d period, consistent with synchronized rotational modulation of surface chemical spots. High-resolution ESPaDOnS circular spectropolarimetry shows a clear Zeeman signature in the line profile of the primary; there is no indication of a magnetic field in the secondary. PHOEBE modelling of the light curve and radial velocities indicates that the two components have almost identical masses of about 3 M_⊙. The primary’s longitudinal magnetic field〈B_z〉 varies between about +100 and −250 G, suggesting a surface magnetic dipole strength B_d = 850 G. Bayesian analysis of the Stokes V profiles indicates B_d = 650 G for the primary and B_d < 110 G for the secondary. The primary’s line profiles are highly variable, consistent with the hypothesis that the out-of-eclipse brightness modulation is a consequence of rotational modulation of that star’s chemical spots. We also detect a residual signal in the light curve after removal of the orbital and rotational modulations, which might be pulsational in origin; this could be consistent with the weak line profile variability of the secondary. This system represents an excellent opportunity to examine the consequences of magnetic fields for stellar structure via comparison of two stars that are essentially identical with the exception that one is magnetic. The existence of such a system furthermore suggests that purely environmental explanations for the origin of fossil magnetic fields are incomplete

On stability of the neutron rich Oxygen isotopes

Stability with respect to neutron emission is studied for highly neutron-excessive Oxygen isotopes in the framework of Hartree-Fock-Bogoliubov approach with Skyrme forces Sly4 and Ska. Our calculations show increase of stability around 40O.Comment: 5 pages, 3 figure

An Efficient Algorithm for Optimizing Adaptive Quantum Metrology Processes

Quantum-enhanced metrology infers an unknown quantity with accuracy beyond the standard quantum limit (SQL). Feedback-based metrological techniques are promising for beating the SQL but devising the feedback procedures is difficult and inefficient. Here we introduce an efficient self-learning swarm-intelligence algorithm for devising feedback-based quantum metrological procedures. Our algorithm can be trained with simulated or real-world trials and accommodates experimental imperfections, losses, and decoherence

Particle Swarm Optimizers for Pareto Optimization with Enhanced Archiving Techniques

During the last decades, numerous heuristic search methods for solving multi-objective optimization problems have been developed. Population oriented approaches such as evolutionary algorithms and particle swarm optimization can be distinguished into the class of archive-based algorithms and algorithms without archive. While the latter may lose the best solutions found so far, archive based algorithms keep track of these solutions. In this article a new particle swarm optimization technique, called DOPS, for multiobjective optimization problems is proposed. DOPS integrates well-known archiving techniques from evolutionary algorithms into particle swarm optimization. Modifications and extensions of the archiving techniques are empirically analyzed and several test functions are used to illustrate the usability of the proposed approach. A statistical analysis of the obtained results is presented. The article concludes with a discussion of the obtained results as well as ideas for further research

Complex taxonomy and global phylogeography of the well-known tropical earthworm Pontoscolex corethrurus

Few earthworm species are peregrine and among them, Pontoscolex corethrurus is the most well-known. Probably native from the Guyana shield, this earthworm is nowadays distributed worldwide, in the tropical and sub-tropical zones. It is found in a wide range of habitats, from apparently pristine to any kind of human-disturbed environments. P. corethrurus presents several characteristics of a successful invader: r-strategy, parthenogenesis reproduction and ecological and reproductive plasticity. Although its ecological interactions with the environment were well documented, the taxonomic status of this earthworm was unclear. We investigated the phylogenetic relationships within the genus Pontoscolex at a global scale (25 countries), focusing on morphologically indistinguishable lineages using the mitochondrial COI and 16S markers, the nuclear ITS 2 and 28S markers and a large-scale multilocus sequence data matrix obtained using the Anchored Hybrid Enrichment (AHE) phylogenomic method. Four cryptic species were discovered within the P. corethrurus species complex and one of them, P. corethrurus L1 was particularly widespread. Although sympatry between L1, L3 and L4 was observed, no case of hybridization was detected between L1 and the two other cryptic species, confirming the status of species of P. corethrurus L1. A population genetics study of this species using COI sequences and AFLP data revealed a low mitochondrial genetic diversity and a high proportion of clones in some populations, in accordance with the principal mode of reproduction of the species (i.e., parthenogenesis). However, variable levels of genetic diversity among populations and results of gametic disequilibrium analysis suggesting recombination in several populations, confirmed a mixed-mating strategy (sexual reproduction and parthenogenesis)

Closedness type regularity conditions for surjectivity results involving the sum of two maximal monotone operators

In this note we provide regularity conditions of closedness type which guarantee some surjectivity results concerning the sum of two maximal monotone operators by using representative functions. The first regularity condition we give guarantees the surjectivity of the monotone operator $S(\cdot + p)+T(\cdot)$, where $p\in X$ and $S$ and $T$ are maximal monotone operators on the reflexive Banach space $X$. Then, this is used to obtain sufficient conditions for the surjectivity of $S+T$ and for the situation when $0$ belongs to the range of $S+T$. Several special cases are discussed, some of them delivering interesting byproducts.Comment: 11 pages, no figure