Pulsar Timing

Millisecond pulsars are excellent clocks, comparable in accuracy to the best atomic clocks on earth. When a gravitational wave is present, either at the pulsar or at the earth. 

TABLE II Physical Data for Modern Cryogenic Resonant Bar Detectors 

Detector ALLEGRO AURIGA EXPLORER NAUTILUS NIOBE 

Material Aluminum Aluminum Aluminum Aluminum Niobium 

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The PULSAR units are high efficiency static aerators that have been developed for municipal wastewater treatment plants and have successfully been used over extended periods of time without any operational problems such as unstable operation or plugging up during intermittent operation of the air pumps (Chourda-kis, 1999). Data have been collected from a pilot plant unit at the Wastewater Treatment plant of the Industrial Park (Herakleion, Crete). A series of experiments were conducted for the determination of the mass transfer coefficient (kLa) and are shown in Figure 17.4. The data are also available in tabular form as part of the parameter estimation input files provided with the enclosed CD. 

This represents an upper limit for the dimensions of the nucleus. Compared with the estimates for the size of the atom, obtained from kinetic theory calculations on gases, which are typically 4x10 9 m. we can see that the nucleus is very small indeed compared to the atom as a whole - a radius ratio of 10-5, or a volume ratio of 10 15, which supports Rutherford s observation that most of an atom consists of empty space. We can also conclude that the density of the nucleus must be extremely high - 1015 times that encountered in ordinary matter, consistent with density estimates in astronomical objects called pulsars or neutron stars. 

Table 1. The relaxation parameters a, and A for the first eight glitches of the Vela pulsar, AQC is the jump value, tg is an interglitch time [16].

Kramer, M. et al. (2003), The Parkes multibeam pulsar survey - III. Young pulsars and the discovery and timing of 200 pulsars , MNRAS 342, 1299. 

Nice, D.J., Splaver, E.M. (2003), Heavy neutron stars A status report on Arecibo timing of four pulsar - white dwarf systems , astro-ph/0311296. 

The fact that our eyes are so exclusively tuned to the Sun has thus blinded us to almost all forms of radiation. This includes radiation from media at very different temperatures, such as the relic cosmological background that filters down to us from the beginning of time, and the great majority of non-thermal emissions, such as the signals from pulsars and supernova remnants. 

Figure 1.14. MRM chromatograms of SCH 29851 (383.0. 337.0) and SCH 34117 (311.1 259.1) obtained using Sciex API 3000 (triple-stage quadrupole) and Sciex QSTAR pulsar (Q-TOF). Comparison of MRM chromatograms of SCH 29851 and SCH 34117 obtained at the LOQ (1 ng/mL) using the API 3000 mass spectrometer with those from the Q-TOF mass spectrometer indicated that the S/N ratio is at least 10-20 times better on the API 3000 mass spectrometer. However, the MRM chromatograms from the API 3000 mass spectrometer do not provide the option to further examine the MS/MS spectra whereas the full-scan MS/MS spectra from a Q-TOF based quantitative bioanalysis assay allows one to easily eliminate any questions about false-positive data. (Rephnted with permission from Yang et a ., 2001b.)...

This is precisely what we see in the Crab Nebula. The rate of the flashes indicates the neutron star is spinning 30 times per second. (Compare that with the Sun s rotation period of about one month.) If a pulsar s beam never sweeps past our line of sight, however, we will never see it. 

Neutron stars have also provided the first direct evidence of planets outside the solar system. The pulsar PSR 1257+12 rotates 161 times per second-but its pulses are not evenly spaced, as are the ones from the Crab. Observations made with the giant Arecibo radio telescope showed that some pulses arrive slightly too soon, others just a bit too late. This means something is tugging the pulsar back and forth slightly. Careful measurements showed that a pair of planets is responsible. 

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