Demonstration of angular anisotropy in the output of Thematic Mapper

There is a dependence of TM output (proportional to scene radiance in a manner which will be discussed) upon season, upon cover type and upon view angle. The existence of a significant systematic variation across uniform scenes in p-type (radiometrically and geometrically pre-processed) data is demonstrated. Present pre-processing does remove the effects and the problem must be addressed because the effects are large. While this is in no way attributable to any shortcomings in the thematic mapper, it is an effect which is sufficiently important to warrant more study, with a view to developing suitable pre-processing correction algorithms

Correlation effects in the density of states of annealed GaMnAs

We report on an experimental study of low temperature tunnelling in hybrid NbTiN/GaMnAs structures. The conductance measurements display a root mean square V dependence, consistent with the opening of a correlation gap in the density of states of GaMnAs. Our experiment shows that low temperature annealing is a direct empirical tool that modifies the correlation gap and thus the electron-electron interaction. Consistent with previous results on boron-doped silicon we find, as a function of voltage, a transition across the phase boundary delimiting the direct and exchange correlation regime.Comment: Replaced with revised version. To appear in Phys. Rev.

Field-induced domain wall propagation: beyond the one-dimensional model

We have investigated numerically the field-driven propagation of perpendicularly magnetized ferromagnetic layers. It was then compared to the historical one-dimensional domain wall (DW) propagation model widely used in spintronics studies of magnetic nanostructures. In the particular regime of layer thickness (h) of the order of the exchange length, anomalous velocity peaks appear in the precessional regime, their shape and position shifting with h. This has also been observed experimentally. Analyses of the simulations show a distinct correlation between the curvature of the DW and the twist of the magnetization vector within it, and the velocity peak. Associating a phenomenological description of this twist with a four-coordinate DW propagation model, we reproduce very well these kinks and show that they result from the torque exerted by the stray field created by the domains on the twisted magnetization. The position of the peaks is well predicted from the DW's first flexural mode frequency, and depends strongly on the layer thickness. Comparison of the proposed model to DW propagation data obtained on dilute semiconductor ferromagnets GaMnAs and GaMnAsP sheds light on the origin of the measured peaks

Multigene phylogeny and mating tests reveal three cryptic species related to Calonectria pauciramosa

Calonectria pauciramosa is a pathogen of numerous plant hosts worldwide. Recent studies have indicated that it included cryptic species, some of which are identified in this study. Isolates from various geographical origins were collected and compared based on morphology, DNA sequence data of the ß-tubulin, histone H3 and translation elongation factor-1 regions and mating compatibility. Comparisons of the DNA sequence data and mating compatibility revealed three new species. These included Ca. colombiana sp. nov. from Colombia, Ca. polizzii sp. nov. from Italy and Ca. zuluensis sp. nov. from South Africa, all of which had distinguishing morphological features. Based on DNA sequence data, Ca. brasiliensis is also elevated to species leve

Resolving conformational changes in FG nucleoporins due to multivalent Karyopherin binding

The nuclear pore complex (NPC) is a huge macromolecular assembly that selectively regulates the exchange of cargo between the nuclear and the cytoplasmic compartment in a cell. The transport of cargo is mediated by nuclear transport receptors (NTR’s), such as Karyopherin, via interacting with NPC proteins (Nucleoporins or Nups) containing highly disordered phenylalanine-glycine (FG) domains. This thesis is an investigation into the structure – function relationship of FG domains, which are located within the nuclear pore complex (NPC) and thus are fundamental to the NPC gating mechanism. Surface plasmon resonance (SPR) is used to measure Karyopherin – FG domain binding affinity and kinetics in vitro near physiological NTR concentrations. To contribute structural information in situ a novel SPR based method is applied that uses non-interacting molecules as innate structural probes. A major part of the thesis is thus dedicated to the proof of concept of using non-interacting molecules to determine the height of surface tethered molecular brushes. The conformation of close-packed surface tethered FG domains reveals molecular brush like extension and is directly impacted by Karyopherin binding. The findings predict that unlike FG centric models NTR’s form a key component of the NPC and NTR-occupancy controls selectivity and speed of nucleo-cytoplasmic transport. This has the important implication that NTR – FG domain binding avidity due to multivalent interactions does not hinder fast transport per se

Secure Vehicular Communication Systems: Implementation, Performance, and Research Challenges

Vehicular Communication (VC) systems are on the verge of practical deployment. Nonetheless, their security and privacy protection is one of the problems that have been addressed only recently. In order to show the feasibility of secure VC, certain implementations are required. In [1] we discuss the design of a VC security system that has emerged as a result of the European SeVeCom project. In this second paper, we discuss various issues related to the implementation and deployment aspects of secure VC systems. Moreover, we provide an outlook on open security research issues that will arise as VC systems develop from today's simple prototypes to full-fledged systems