Preliminary note on the paleomagnetic reversal record obtained from two Mallorcan caves

[spa] Muestras de sedimentos obtenidas en dos cuevas mallorquinas con la ayuda del Speleo Club Mallorca, ponen de manifiesto una inversión del campo magnético terrestre en puntos sincrónicos de ambos depósitos (alrededor de un metro de profundidad). Esta inversión es la primera que ha sido observada en sedimentos de cueva, pareciendo corresponder al período "Mungo" que finalizó hace unos 32.000 años. Previamente, el "Mungo" solamente había sido identificado en sedimentos lacustres de Australia y en sedimentos marinos profundos del Golfo de Méjico.[eng] Sediments samples obtained from two Mallorcan caves with the help of the Speleo Club Mallorca show a reversal of the earth's magnetic field at synchronous points in the two deposits, circa 1m (Fig. 1). This reversal is the first ever observed in cave sediments and it is thought to be the Mungo event which ended about 32.000 B.P. Previously, the Mungo event had only identified in lake sediments from Australia and deepsea sediments from the Gulf of México (Freed and Healy 1974)

Resolving Target Ambiguity in 3D Gaze Interaction through VOR Depth Estimation

Target disambiguation is a common problem in gaze interfaces, as eye tracking has accuracy and precision limitations. In 3D environments this is compounded by objects overlapping in the field of view, as a result of their positioning at different depth with partial occlusion. We introduce \textit{VOR depth estimation}, a method based on the vestibulo-ocular reflex of the eyes in compensation of head movement, and explore its application to resolve target ambiguity. The method estimates gaze depth by comparing the rotations of the eye and the head when the users look at a target and deliberately rotate their head. We show that VOR eye movement presents an alternative to vergence for gaze depth estimation, that is feasible also with monocular tracking. In an evaluation of its use for target disambiguation, our method outperforms vergence for targets presented at greater depth

One-loop Beta Functions for the Orientable Non-commutative Gross-Neveu Model

We compute at the one-loop order the beta-functions for a renormalisable non-commutative analog of the Gross Neveu model defined on the Moyal plane. The calculation is performed within the so called x-space formalism. We find that this non-commutative field theory exhibits asymptotic freedom for any number of colors. The beta-function for the non-commutative counterpart of the Thirring model is found to be non vanishing.Comment: 16 pages, 9 figure

Noncommutative Induced Gauge Theory

We consider an external gauge potential minimally coupled to a renormalisable scalar theory on 4-dimensional Moyal space and compute in position space the one-loop Yang-Mills-type effective theory generated from the integration over the scalar field. We find that the gauge invariant effective action involves, beyond the expected noncommutative version of the pure Yang-Mills action, additional terms that may be interpreted as the gauge theory counterpart of the harmonic oscillator term, which for the noncommutative $\phi^4$-theory on Moyal space ensures renormalisability. The expression of a possible candidate for a renormalisable action for a gauge theory defined on Moyal space is conjectured and discussed.Comment: 20 pages, 6 figure

Lateral Distribution of Muons in IceCube Cosmic Ray Events

In cosmic ray air showers, the muon lateral separation from the center of the shower is a measure of the transverse momentum that the muon parent acquired in the cosmic ray interaction. IceCube has observed cosmic ray interactions that produce muons laterally separated by up to 400 m from the shower core, a factor of 6 larger distance than previous measurements. These muons originate in high pT (> 2 GeV/c) interactions from the incident cosmic ray, or high-energy secondary interactions. The separation distribution shows a transition to a power law at large values, indicating the presence of a hard pT component that can be described by perturbative quantum chromodynamics. However, the rates and the zenith angle distributions of these events are not well reproduced with the cosmic ray models tested here, even those that include charm interactions. This discrepancy may be explained by a larger fraction of kaons and charmed particles than is currently incorporated in the simulations