The theory of stellar winds

We present a brief overview of the theory of stellar winds with a strong emphasis on the radiation-driven outflows from massive stars. The resulting implications for the evolution and fate of massive stars are also discussed. Furthermore, we relate the effects of mass loss to the angular momentum evolution, which is particularly relevant for the production of long and soft gamma-ray bursts. Mass-loss rates are not only a function of the metallicity, but are also found to depend on temperature, particularly in the region of the bi-stability jump at 21 000 Kelvin. We highlight the role of the bi-stability jump for Luminous Blue Variable (LBV) stars, and discuss suggestions that LBVs might be direct progenitors of supernovae. We emphasize that radiation-driven wind studies rely heavily on the input opacity data and linelists, and that these are thus of fundamental importance to both the mass-loss predictions themselves, as well as to our overall understanding of the lives and deaths of massive stars.Comment: 6 pages, invited review Astrophysics and Space Science, Vol 336, Issue 1, pp. 163-167 (special HEDLA 2010 Issue

The bioengineering of targeted serpins

For the computer floppy diskette accompanying this thesis; please apply to the issuing universitySIGLEAvailable from British Library Document Supply Centre- DSC:D062820 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The feedback of massive stars on interstellar astrochemical processes

Astrochemistry is a discipline that studies physico-chemical processes in astrophysical environments. Such environments are characterized by conditions that are substantially different from those existing in usual chemical laboratories. Models which aim to explain the formation of molecular species in interstellar environments must take into account various factors, including many that are directly, or indirectly related to the populations of massive stars in galaxies. The aim of this paper is to review the influence of massive stars, whatever their evolution stage, on the physico-chemical processes at work in interstellar environments. These influences include the ultraviolet radiation field, the production of high energy particles, the synthesis of radionuclides and the formation of shocks that permeate the interstellar medium

The opportunities and challenges associated with wireless interconnects in aircraft

Utilizing wireless data buses in aircraft has the potential to increase reliability, reduce weight, and improve flexibility and adaptability. In this article, the implementation of wirelessly connected interconnects in aircraft is introduced from a broad perspective, considering the issues of radio systems, propagation, antennas, and applications.Existing avionics systems are discussed briefly in order to understand the requirements placed on a wireless system and the specification it must meet. A review of existing wireless protocols and commercial off the shelf systems is provided, explaining where systems including ZigBee and IEEE 802.11 are suitable and unsuitable for a wireless aircraft application, and it is found that no existing system can be used exclusively. It is shown quantitatively that the propagation environment is expected to have high delay spreads and the negative impact of this on system reliability is shown through simulation and measurements.The application and benefits of a direct write, in-situ, metallic deposition procedure are discussed for the placement of antennas, sensors, and their associated electronics. By writing electronics onto a surface, fitting and retrofitting are made much easier without the need to affect the aircraft structure, and this enables a more flexible wireless system. The opportunities, advantages and challenges for such a technology within the wireless aircraft are discussed

Co-aggregation with apolipoprotein E modulates the function of amyloid-β in Alzheimer's disease

Which isoforms of apolipoprotein E (apoE) we inherit determine our risk of developing late-onset Alzheimer’s Disease (AD), but the mechanism underlying this link is poorly understood. In particular, the relevance of direct interactions between apoE and amyloid-β (Aβ) remains controversial. Here, single-molecule imaging shows that all isoforms of apoE associate with Aβ in the early stages of aggregation and then fall away as fibrillation happens. ApoE-Aβ co-aggregates account for ~50% of the mass of diffusible Aβ aggregates detected in the frontal cortices of homozygotes with the higher-risk APOE4 gene. We show how dynamic interactions between apoE and Aβ tune disease-related functions of Aβ aggregates throughout the course of aggregation. Our results connect inherited APOE genotype with the risk of developing AD by demonstrating how, in an isoform- and lipidation-specific way, apoE modulates the aggregation, clearance and toxicity of Aβ. Selectively removing non-lipidated apoE4-Aβ co-aggregates enhances clearance of toxic Aβ by glial cells, and reduces secretion of inflammatory markers and membrane damage, demonstrating a clear path to AD therapeutics