ELECTRON-DENSITY FLUCTUATIONS IN THE LOCAL INTERSTELLAR BUBBLE
NATURE
Authors: PHILLIPS, JA; CLEGG, AW
Abstract
THE interstellar medium in our vicinity forms an elongated cavity of X-ray-emitting gas, extending up to 200 pc from the Sun1,2. The gas inside this local bubble is very hot (approximately 10(6) K) and tenuous (electron density n(e) almost-equal-to 0.005 cm-3), and is typical of material in the coronal phase of the interstellar medium, thought to occur when hot stars or supernovae blow out holes in cooler and denser interstellar gas. Little is known about turbulent density fluctuations in the coronal gas, but its physical state is important in understanding cosmic ray confinement and the energy balance of interstellar material, as well as the scattering of radio emission from compact sources3,4. To probe turbulence in the local interstellar medium, we have made scintillation measurements at 50 MHz (6 m wavelength) of emission from the nearby pulsar 0950+08, which happens to lie near the edge of the local bubble. From the scintillation bandwidth we deduce the amplitude of the electron-density fluctuation spectrum in the coronal gas alone, and find it to be an order of magnitude lower than for any previously measured interstellar line of sight. We conclude that the interior of the bubble is relatively quiescent and that high levels of plasma turbulence-if they exist-must be localized to the cavity boundary.
Nesprins LINC the nucleus and cytoskeleton
CURRENT OPINION IN CELL BIOLOGY
Authors: Mellad, Jason A.; Warren, Derek T.; Shanahan, Catherine M.
Abstract
Like other spectrin repeat proteins, nesprins co-ordinate and maintain cellular architecture by linking membranous organelles to the cytoskeleton. However nuclear envelope (NE) nesprins, uniquely hardwire the nuclear lamina to the cytoskeleton and molecular motors. Emerging evidence suggests that nesprins also form a continuous network linking the plasma membrane to the NE that potentially translates mechanical stimuli into nuclear reorganisation. Surprisingly, this network is also essential for cytoskeletal organisation and its disruption has dramatic effects on nuclear migration, centrosomal positioning, focal adhesion maturation and cell motility. Herein we review recent advances in our understanding of how nesprins couple to various filamentous systems within the cell and emphasise the importance of both KASH and KASH-less nesprin isoforms in these interactions.