1Mpc). It is generally assumed that magnetic fields in spiral galaxies arise from the combined action of differential rotation and helical turbulence, a process known as the αω-dynamo. However fundamental questions concerning the nature of the dynamo as well as the origin of the seed fields necessary to prime it remain unclear. Moreover, the standard αω-dynamo does not explain the existence of ...

Magnetic fields in spiral galaxies have strengths of order few 10−6G, and are coherent on scales of several kpc [1]. In several disk galaxies, like M51 and NGC 6946, they are also highly correlated (or anti-correlated) with the optical spiral arms. How do such ordered, large-scale fields arise? One possibility is dynamo amplification of a weak but nonzero seed field ∼ 10−19 − 10−23G, provided t...

Genomic imprinting is an epigenetic phenomenon causing parent-of-origin specific differential expression of maternally and paternally inherited alleles. While many imprinted genes have been identified in plants, the functional roles of most of them are unknown. In this study, we systematically examine the functional requirement of paternally expressed imprinted genes (PEGs) during seed developm...

The genus Messor consists of 113 species of seed harvesting ants that are found in grasslands, semi-arid areas and savannahs in both the Old and New World. A full spectrum of foraging strategies occurs in Messor, ranging from individual to group foraging, with the latter having evolved several times. This paper reviews foraging strategies and the underlying behavioral mechanisms found in specie...

Cancer cells that leave the primary tumor can seed metastases in distant organs, and it is thought that this is a unidirectional process. Here we show that circulating tumor cells (CTCs) can also colonize their tumors of origin, in a process that we call "tumor self-seeding." Self-seeding of breast cancer, colon cancer, and melanoma tumors in mice is preferentially mediated by aggressive CTCs, ...

The all-sky survey of Faraday rotation, a Key Science Project of the planned Square Kilometre Array, will accumulate tens of millions of rotation measure measurements toward background radio sources and will provide a unique database for characterizing the overall magnetic geometry of magnetic fields in galaxies and in the intergalactic medium. Deep imaging of the polarized synchrotron emission...

The ubiquitous and conserved cytosolic heat-shock proteins 90 (HSP90A) perform essential functions in the cell. To understand the evolutionary origin of HSP90A functional diversification, we analyzed the distribution of HSP90A family from 54 species representing the main eukaryotic lineages. Three independent HSP90A duplications led to the paralog subfamilies HSP90AA (heat-stress inducible) and...

We study a model of seed dispersal that considers the inclusion of an animal disperser moving diffusively, feeding on fruits and transporting the seeds, which are later deposited and capable of germination. The dynamics depends on several population parameters of growth, decay, harvesting, transport, digestion and germination. In particular, the deposition of transported seeds at places away fr...

Knowledge about the crop biology of economic crops in Africa is needed for regulators to accurately review dossiers and conduct comprehensive environmental risk assessments (ERAs). This information allows regulators to decide whether biotech crops present a risk to biodiversity, since crossing between domesticated crops and their wild relatives could affect the adaptations of the wild species. ...

We present a new model for the formation of black holes in cosmological simulations, motivated by the first star formation. Black holes form from high density peaks of primordial gas, and grow via both gas accretion and mergers. Massive black holes heat the surrounding material, suppressing star formation at the centres of galaxies, and driving galactic winds. We perform an investigation into t...