Robust 3D target localization using UAVs with state uncertainty

[no abstract available

Triangle Diagram with Off-Shell Coulomb T-Matrix for (In-)Elastic Atomic and Nuclear Three-Body Processes

The driving terms in three-body theories of elastic and inelastic scattering of a charged particle off a bound state of two other charged particles contain the fully off-shell two-body Coulomb T-matrix describing the intermediate-state Coulomb scattering of the projectile with each of the charged target particles. Up to now the latter is usually replaced by the Coulomb potential, either when using the multiple-scattering approach or when solving three-body integral equations. General properties of the exact and the approximate on-shell driving terms are discussed, and the accuracy of this approximation is investigated numerically, both for atomic and nuclear processes including bound-state excitation, for energies below and above the corresponding three-body dissociation threshold, over the whole range of scattering angles.Comment: 22 pages, 11 figures, figures can be obtained upon request from the Authors, revte

The Ten Martini Problem

We prove the conjecture (known as the ``Ten Martini Problem'' after Kac and Simon) that the spectrum of the almost Mathieu operator is a Cantor set for all non-zero values of the coupling and all irrational frequencies.Comment: 31 pages, no figure

Effect of doping-- and field--induced charge carrier density on the electron transport in nanocrystalline ZnO

Charge transport properties of thin films of sol--gel processed undoped and Al-doped zinc oxide nanoparticles with variable doping level between 0.8 at% and 10 at% were investigated. The X-ray diffraction studies revealed a decrease of the average crystallite sizes in highly doped samples. We provide estimates of the conductivity and the resulting charge carrier densities with respect to the doping level. The increase of charge carrier density due to extrinsic doping were compared to the accumulation of charge carriers in field effect transistor structures. This allowed to assess the scattering effects due to extrinsic doping on the electron mobility. The latter decreases from 4.6*10^-3 cm^2/Vs to 4.5*10^-4 cm^2/Vs with increasing doping density. In contrast, the accumulation leads to an increasing mobility up to 1.5*10^-2 cm^2/Vs. The potential barrier heights related to grain boundaries between the crystallites were derived from temperature dependent mobility measurements. The extrinsic doping initially leads to a grain boundary barrier height lowering, followed by an increase due to doping-induced structural defects. We conclude that the conductivity of sol--gel processed nanocrystalline ZnO:Al is governed by an interplay of the enhanced charge carrier density and the doping-induced charge carrier scattering effects, achieving a maximum at 0.8 at% in our case.Comment: 8 pages, 7 figure

Bloch Electrons in a Magnetic Field - Why Does Chaos Send Electrons the Hard Way?

We find that a 2D periodic potential with different modulation amplitudes in x- and y-direction and a perpendicular magnetic field may lead to a transition to electron transport along the direction of stronger modulation and to localization in the direction of weaker modulation. In the experimentally accessible regime we relate this new quantum transport phenomenon to avoided band crossing due to classical chaos.Comment: 4 pages, 3 figures, minor modifications, PRL to appea

SoundCloud and Bandcamp as alternative music platforms

We examine two ‘producer-oriented’ audio distribution platforms, SoundCloud and Bandcamp, that have been important repositories for the hopes of musicians, commentators and audiences that digital technologies and cultural platforms might promote democratisation of the cultural industries, and we compare their achievements and limitations in this respect. We show that the emancipatory elements enshrined in SoundCloud’s ‘bottom-up’ abundance are compromised by two elements that underpin the platform: the problematic ‘culture of connectivity’ of the social media systems to which it must remain integrally linked, and the systems of intellectual property that the firm has been increasingly compelled to enforce. By contrast, it seems that Bandcamp has been relatively stable in financial terms while being at odds with some key aspects of ‘platformization’, and we explore the possibility that some of the platform’s apparent success may derive from how its key features makes it attractive to indie musicians and fans drawn to an independent ethos. Nevertheless, we argue, even while in some respects Bandcamp acts more effectively as an ‘alternative’ than does SoundCloud, the former is also congruent economically and discursively with how platforms capitalise on the activity of self-managing, self-auditing, specialist, worker-users