Chromatin and epigenetics: current biophysical views

Recent advances in high-throughput sequencing experiments and their theoretical descriptions have determined fast dynamics of the "chromatin and epigenetics" field, with new concepts appearing at high rate. This field includes but is not limited to the study of DNA-protein-RNA interactions, chromatin packing properties at different scales, regulation of gene expression and protein trafficking in the cell nucleus, binding site search in the crowded chromatin environment and modulation of physical interactions by covalent chemical modifications of the binding partners. The current special issue does not pretend for the full coverage of the field, but it rather aims to capture its development and provide a snapshot of the most recent concepts and approaches. Eighteen open-access articles comprising this issue provide a delicate balance between current theoretical and experimental biophysical approaches to uncover chromatin structure and understand epigenetic regulation, allowing free flow of new ideas and preliminary results

Self-consistent gyrokinetic modeling of neoclassical and turbulent impurity transport

International audienceTrace impurity transport is studied with the flux-driven gyrokinetic GYSELA code [V. Grandgirard et al., Comp. Phys. Commun. 207, 35 (2016)]. A reduced and linearized multi-species collision operator has been recently implemented, so that both neoclassical and turbulent transport channels can be treated self-consistently on an equal footing. In the Pfirsch-Schlüter regime likely relevant for tungsten, the standard expression of the neoclassical impurity flux is shown to be recovered from gyrokinetics with the employed collision operator. Purely neoclassical simulations of deuterium plasma with trace impurities of helium, carbon and tungsten lead to impurity diffusion coefficients, inward pinch velocities due to density peaking, and thermo-diffusion terms which quantitatively agree with neoclassical predictions and NEO simulations [E. Belli et al., Plasma Phys. Control. Fusion 54, 015015 (2012)]. The thermal screening factor appears to be less than predicted analytically in the Pfirsch-Schlüter regime, which can be detrimental to fusion performance. Finally, self-consistent nonlinear simulations have revealed that the tungsten impurity flux is not the sum of turbulent and neoclassical fluxes computed separately, as usually assumed. The synergy partly results from the turbulence-driven in-out poloidal asymmetry of tungsten density. This result puts forward the need for self-consistent simulations of impurity transport, i.e. including both turbulence and neoclassical physics, in view of quantitative predictions for ITER

Intraoperative complications of laparoscopic adrenalectomy

A laparoscopic or retroperitoneoscopic access to the adrenal gland is the standard of care for adrenalectomy in most cases. Although in laparoscopic adrenalectomy the approach is minimally invasive, the procedure is challenging. This is reflected in the scope of possible complications. The surgeon must consider complications related to the anatomical topography of the adrenal gland, which typically encompasses the complications known from open surgery and complications related to the minimal invasive access. In this topic paper we will address the most frequently encountered complications of adrenalectomy: vascular injuries, injuries of the bowel, pleural tears, and injuries to the liver, spleen and pancreas. Fortunately, these complications occur rarely. However, many of these complications can have devastating consequences. Therefore, it's the surgeon's obligation to be aware of the possible complications he might encounter during laparoscopic adrenalectomy. This awareness is essential for their prevention and it helps the laparoscopic surgeon to identify complications intraoperatively