Electronic Structure, Local Moments and Transport in Fe_2VAl

Local spin density approximation calculations are used to elucidate electronic and magnetic properties of Heusler structure Fe_2VAl. The compound is found to be a low carrier density semimetal. The Fermi surface has small hole pockets derived from a triply degenerate Fe derived state at Gamma compensated by an V derived electron pocket at the X point. The ideal compound is found to be stable against ferromagnetism. Fe impurities on V sites, however, behave as local moments. Because of the separation of the hole and electron pockets the RKKY interaction between such local moments should be rapidly oscillating on the scale of its decay, leading to the likelihood of spin-glass behavior for moderate concentrations of Fe on V sites. These features are discussed in relation to experimental observations of an unusual insulating state in this compound.Comment: 16 pages, RevTeX, 5 figure

Lack of observational evidence for quantum structure of space-time at Plank scales

It has been noted (Lieu & Hillmann, 2002) that the cumulative affect of Planck-scale phenomenology, or the structure of space-time at extremely small scales, can be lead to the loss of phase of radiation emitted at large distances from the observer. We elaborate on such an approach and demonstrate that such an effect would lead to an apparent blurring of distant point-sources. Evidence of the diffraction pattern from the HST observations of SN 1994D and the unresolved appearance of a Hubble Deep Field galaxy at z=5.34 lead us to put stringent limits on the effects of Planck-scale phenomenology.Comment: 12 pages, 3 figures, accepter for ApJ

The disruption of proteostasis in neurodegenerative diseases

Cells count on surveillance systems to monitor and protect the cellular proteome which, besides being highly heterogeneous, is constantly being challenged by intrinsic and environmental factors. In this context, the proteostasis network (PN) is essential to achieve a stable and functional proteome. Disruption of the PN is associated with aging and can lead to and/or potentiate the occurrence of many neurodegenerative diseases (ND). This not only emphasizes the importance of the PN in health span and aging but also how its modulation can be a potential target for intervention and treatment of human diseases.info:eu-repo/semantics/publishedVersio