Use of LANDSAT data for automatic classification and area estimation of sugarcane plantation in Sao Paulo state, Brazil

Ten segments of the size 20 x 10 km were aerially photographed and used as training areas for automatic classifications. The study areas was covered by four LANDSAT paths: 235, 236, 237, and 238. The percentages of overall correct classification for these paths range from 79.56 percent for path 238 to 95.59 percent for path 237

Higher Harmonics in Non-Linear Vacuum from QED Effects Without Low Mass Intermediate Particles

We show that in the presence of a slowly rotating strong transverse magnetic field there is an infinite spectrum of harmonic wave functions $A_n$ due to the first order QED correction (in $\alpha^2$) given by the Euler-Heisenberg Lagrangian. The frequency shifts are integer multiples $\pm \omega_0 n$ of the magnetic field angular frequency rotation $\omega_0=2\pi\nu_m$ and the several modes $n$ are coupled to the nearest harmonics $n\pm 1$. This is a new effect due to QED vacuum fluctuations, not exploit before, that can explain, both qualitatively and quantatively, the recent experimental results of the PVLAS collaboration without the need of a low mass intermediate particle, hence dismiss the recent claim of the discovery of the axion. [Erratum: The PVLAS signal cannot be explained by this mechanism.]Comment: 4 pages, 1 figure; includes Erratum: The PVLAS signal cannot be explained by this mechanis

Rise in the frequency of cloud cover in LANDSAT data for the period 1973 to 1981

Percentages of cloud cover in LANDSAT imagery were used to calculate the cloud cover monthly average statistic for each LANDSAT scene in Brazil, during the period of 1973 to 1981. The average monthly cloud cover and the monthly minimum cloud cover were also calculated for the regions of north, northeast, central west, southeast and south, separately

Heuristic for estimation of multiqubit genuine multipartite entanglement

For every N-qubit density matrix written in the computational basis, an associated "X-density matrix" can be obtained by vanishing all entries out of the main- and anti-diagonals. It is very simple to compute the genuine multipartite (GM) concurrence of this associated N-qubit X-state, which, moreover, lower bounds the GM-concurrence of the original (non-X) state. In this paper, we rely on these facts to introduce and benchmark a heuristic for estimating the GM-concurrence of an arbitrary multiqubit mixed state. By explicitly considering two classes of mixed states, we illustrate that our estimates are usually very close to the standard lower bound on the GM-concurrence, being significantly easier to compute. In addition, while evaluating the performance of our proposed heuristic, we provide the first characterization of GM-entanglement in the steady states of the driven Dicke model at zero temperature.Comment: 19 pages, 5 figure