Results 1 - 10 of 3164
Results 1 - 10 of 3164. Search took: 0.028 seconds
|Sort by: date | relevance|
[en] This thesis describes the Princeton-NRAO Phase II pulsar survey, carried out at 390 MHz using the 92-m telescope in Green Bank, West Virginia. This search is the first to have sensitivity to pulsars with periods as short as 0.004 s over a large portion of the galatic plane. Twenty new pulsars were discovered and 67 previously known ones were detected. Though 6 pulsars were detected with periods below 0.200 s, none were found with periods shorter than 0.100 s. This result places strong upper limits on the population of short-period pulsars, and effectively rules out the existence of a large, previously unobserved pulsar population with periods between 0.005 and 0.100 s. The observed period distribution is in good agreement with that predicted by the model of Lyne, Manchester, and Taylor (1985), and can be accounted for without invoking either late turn-on or spin-up of pulsars
[en] Very recently Farhat et al (2011, Phys. Rev. B 84 235105) suggested that arrays of invisibility cloaks may find important applications in low-interference communication, noninvasive probing, sensing and communication networks and so on. We report on the first experimental realization of such an array of broadband invisibility cloaks that operates in the visible frequency range. The wavelength and angular dependences of the cloak array performance have been studied. (paper)
[en] An elementary derivation is given for the shape of the wake pattern of a boat traveling at constant velocity in deep water. We find essentially the same results as those found in standard treatments, but our mathematics is easier. All results follow from the fact that the group velocity is half the phase velocity
[en] The complex conductivity of a MgB2 film has been investigated in the frequency range 4<ν<30 cm-1 and for temperatures 2.7< T<300 K . The overall temperature dependence of both components of the complex conductivity is reminiscent of BCS-type behavior, although a detailed analysis reveals a number of discrepancies. A peak in the temperature dependence of the real part of the conductivity is detected for frequencies below 9 cm-1 . The superconducting penetration depth follows a T2 behavior at low temperatures
[en] Observation data on gravimagnetic disturbances of the ultra-low frequency range during large earthquakes are given. An experimental result, which reflects the increase in evolving gravimagnetic process of the Earth’s geospheres during preparation of a seismic event, is analyzed. The conditions of origination and evolution of gravimagnetic disturbances are specified.
[en] We have used optical spectroscopy to probe the normal state electrodynamic response of Fe1.06Te0.88S0.14, a member of the 11 family of iron-based superconductors with Tc = 8 K. Measurements have been conducted over a wide frequency range (50-50,000 cm-1) at selected temperatures between 10 and 300 K. At low temperatures the material behaves as an 'incoherent metal: a Drude-type peak is absent from the optical conductivity and all optical functions reveal that quasiparticles are not well defined down to the lowest measured temperature. We introduce 'generalized spectral weight' analysis and use it to track temperature induced redistribution of spectral weight. Our results, combined with previous reports, indicate that the 11 family of iron-based superconductors might be different from other families.
[en] Recent analyses of pulses from pulsars carried out by a number of workers are reviewed. Integrated pulses (the addition of pulses giving single, double or more complex shapes), subpulses, and the very fine time-scale structure known as microstructure, are discussed. Models, especially the so-called light cylinder models, which have been advanced to explain the emission mechanism of pulsars are examined. (U.K.)