LSA silicon material task closed-cycle process development

The initial effort on feasibility of the closed cycle process was begun with the design of the two major items of untested equipment, the silicon tetrachloride by product converter and the rotary drum reactor for deposition of silicon from trichlorosilane. The design criteria of the initial laboratory equipment included consideration of the reaction chemistry, thermodynamics, and other technical factors. Design and construction of the laboratory equipment was completed. Preliminary silicon tetrachloride conversion experiments confirmed the expected high yield of trichlorosilane, up to 98 percent of theoretical conversion. A preliminary solar-grade polysilicon cost estimate, including capital costs considered extremely conservative, of $6.91/kg supports the potential of this approach to achieve the cost goal. The closed cycle process appears to have a very likely potential to achieve LSA goals

Murdoch and the End of Ideology

Iris Murdoch had a lifelong interest in politics and she reflected upon the nature of ideology throughout her career. What she had to say on the subject developed during her career and relates to general academic discussions on the nature of ideology. At the outset of her career she was a committed socialist. She recognised that political ideology was in retreat after the Second World War but sought to contribute to socialist ideology. Later in her career she became sceptical of radical utopian ideologies, including socialism and developed a theory of politics that prioritised safeguarding individual liberty and security. However, she imagined that political thought would continue to develop and offer new possibilities and so she did not call for the end of ideology but continued to value political ideas

Two-fluid and magnetohydrodynamic modelling of magnetic reconnection in the MAST spherical tokamak and the solar corona

Twisted magnetic flux ropes are ubiquitous in space and laboratory plasmas, and the merging of such flux ropes through magnetic reconnection is an important mechanism for restructuring magnetic fields and releasing free magnetic energy. The merging-compression scenario is one possible start up scheme for spherical tokamaks, which has been used on the Mega Amp Spherical Tokamak MAST. Two current-carrying plasma rings, or flux ropes, approach each other through the mutual attraction of their like currents, and merge, through magnetic reconnection, into a single plasma torus, with substantial plasma heating. 2D resistive MHD and Hall MHD simulations of this process are reported, and new results for the temperature distribution of ions and electrons are presented. A model of the based on relaxation theory is also described, which is now extended to tight aspect ratio geometry. This model allows prediction of the final merged state and the heating. The implications of the relaxation model for heating of the solar corona are also discussed, and a model of the merger of two or more twisted coronal flux ropes is presented, allowing for different senses of twist

Severe Scene Learning Impairment, but Intact Recognition Memory, after Cholinergic Depletion of Inferotemporal Cortex Followed by Fornix Transection

To examine the generality of cholinergic involvement in visual memory in primates, we trained macaque monkeys either on an object-in-place scene learning task or in delayed nonmatching-to-sample (DNMS). Each monkey received either selective cholinergic depletion of inferotemporal cortex (including the entorhinal cortex and perirhinal cortex) with injections of the immunotoxin ME20.4-saporin or saline injections as a control and was postoperatively retested. Cholinergic depletion of inferotemporal cortex was without effect on either task. Each monkey then received fornix transection because previous studies have shown that multiple disconnections of temporal cortex can produce synergistic impairments in memory. Fornix transection mildly impaired scene learning in monkeys that had received saline injections but severely impaired scene learning in monkeys that had received cholinergic lesions of inferotemporal cortex. This synergistic effect was not seen in monkeys performing DNMS. These findings confirm a synergistic interaction in a macaque monkey model of episodic memory between connections carried by the fornix and cholinergic input to the inferotemporal cortex. They support the notion that the mnemonic functions tapped by scene learning and DNMS have dissociable neural substrates. Finally, cholinergic depletion of inferotemporal cortex, in this study, appears insufficient to impair memory functions dependent on an intact inferotemporal cortex

Deciphering solar turbulence from sunspots records

It is generally believed that sunspots are the emergent part of magnetic flux tubes in the solar interior. These tubes are created at the base of the convection zone and rise to the surface due to their magnetic buoyancy. The motion of plasma in the convection zone being highly turbulent, the surface manifestation of sunspots may retain the signature of this turbulence, including its intermittency. From direct observations of sunspots, and indirect observations of the concentration of cosmogenic isotopes $^{14}$C in tree rings or $^{10}$Be in polar ice, power spectral densities in frequency are plotted. Two different frequency scalings emerge, depending on whether the Sun is quiescent or active. %magnetic activity is maximum or minimum. From direct observations we can also calculate scaling exponents. These testify to a strong intermittency, comparable with that observed in the solar wind.Comment: 5 pages, 6 figures, accepted for publication in MNRAS Letter

Seismic evolution of low/intermediate mass PMS stars

This article presents a study of the evolution of the internal structure and seismic properties expected for low/intermediate mass Pre-Main Sequence (PMS) stars. Seismic and non-seismic properties of PMS stars were analysed. This was done using 0.8 to 4.4M$_\odot$ stellar models at stages ranging from the end of the Hayashi track up to the Zero-Age Main-Sequence (ZAMS). This research concludes that, for intermediate-mass stars (M$>$1.3M$_\odot$), diagrams comparing the effective temperature ($T_{eff}$) against the small separation can provide an alternative to Christensen-Dalsgaard (C-D) diagrams. The impact of the metal abundance of intermediate mass stars (2.5-4.4M$_\odot$) has over their seismic properties is also evaluated.Comment: 4 pages, 5 figures, accepted for publication on A&