RESUMO
This Letter presents a study of the local density of states (LDOS) in photonic quasicrystals. We show that the LDOS of a Penrose-type quasicrystal exhibits small additional band gaps. Among the band gaps, some exhibit a behavior similar to that typical of photonic crystals, while others do not. The development of certain band gaps requires large-size quasicrystals. It is explained by the long-range interactions involved in their formation. Moreover, the frequencies where the band gaps occur are not necessarily explained using single scattering and should therefore involve multiple scattering.
RESUMO
In [Phys. Rev. E 57, 6470 (1998)]] a thorough characterization in terms of receiver operating characteristics of stochastic-resonance detectors of weak harmonic signals of known frequency in additive Gaussian noise was given. It was shown that strobed sign-counting based strategies can be used to achieve a nice trade-off between performance and cost, by comparison with noncoherent correlators. Here we discuss the more realistic case where besides the sought signal (whose frequency is assumed known) further unwanted spectrally nearby signals with comparable amplitude are present. Rejection properties are discussed in terms of suitably defined false-alarm and false-dismissal probabilities for various values of interfering signal(s) strength and spectral separation.
RESUMO
The histologic types of lung cancer in 855 patients (747 men and 107 women) from three hospitals and one international study of insulation workers were evaluated. Of these, 196 cases had asbestos exposure. About one half of the cases were diagnosed from surgical slides and one half from autopsy slides. Squamous cell carcinoma constituted the largest percentage of tumor types and was found with the same frequency in exposed and nonexposed groups. Small cell carcinoma was found in 25% of the exposed and in 15% of the nonexposed patients. Upper lung sites were involved in about two thirds of the cases with asbestos exposure and lower lobes in the other one third. There was little difference in histologic type in cases regardless of whether upper or lower lobes were involved. Cigarette smokers who smoked until their cancer diagnosis showed no difference in histologic type by amount smoked, and slight but not statistically significant differences from ex-cigarette smokers.