6,801 research outputs found

    The spectral energy distribution of NGC 1275

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    An analysis of absolute spectral energy distributions of interstellar gas for a galaxy (NGC 1275) is presented. Infrared spectra data shows heavy reddening. It is proposed that the interstellar gas may be ionized by shock waves or by nonthermal or stellar radiation. It is suggested, that high velocity, emission-line knots are H2 regions in a Perseus cluster galaxy or intergalactic gas cloud seen in projection against NGC 1275

    A Radio Transmitter for Quail

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    This paper describes a small radio-transmitter that has been developed specifically for use on quail. The transmitter weighs 5g, is disk-shaped (25mm diameter X 7mm thick) and is worn on the chest. It is kept in place by a harness made from nylon covered, stainless-steel wire that also functions as the antenna. Because of the transmitter\u27s light weight, shape, and position, quail seem to tolerate it very well. Also, it cannot be seen by aerial predators. The nominal signal consists of 30 msec pulses with a frequency of 1 ha. Movement produces one extra 40 rnsec pulse per cycle, 500 msec after the 30 msec pulse. These characteristics allow for relatively simple automatic detection and recording of activity. The transmission range, using a commercially available 3-element Yagi and receiver, exceeds one-half mile. Life expectancy is about 60 days. Components for the transmitter cost about $25.00 (1981)

    The Black Hole Mass - Galaxy Bulge Relationship for QSOs in the SDSS DR3

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    We investigate the relationship between black hole mass and host galaxy velocity dispersion for QSOs in Data Release 3 of the Sloan Digital Sky Survey. We derive black hole mass from the broad Hbeta line width and continuum luminosity, and the bulge stellar velocity dispersion from the [OIII] narrow line width. At higher redshifts, we use MgII and [OII] in place of Hbeta and [OIII]. For redshifts z < 0.5, our results agree with the black hole mass - bulge velocity dispersion relationship for nearby galaxies. For 0.5 < z < 1.2, this relationship appears to show evolution with redshift in the sense that the bulges are too small for their black holes. However, we find that part of this apparent trend can be attributed to observational biases, including a Malmquist bias involving the QSO luminosity. Accounting for these biases, we find ~0.2 dex evolution in the black hole mass-bulge velocity dispersion relationship between now and redshift z ~ 1.Comment: Accepted by ApJ, 15 pages, 9 figure

    Practical security bounds against the Trojan-horse attack in quantum key distribution

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    In the quantum version of a Trojan-horse attack, photons are injected into the optical modules of a quantum key distribution system in an attempt to read information direct from the encoding devices. To stop the Trojan photons, the use of passive optical components has been suggested. However, to date, there is no quantitative bound that specifies such components in relation to the security of the system. Here, we turn the Trojan-horse attack into an information leakage problem. This allows us quantify the system security and relate it to the specification of the optical elements. The analysis is supported by the experimental characterization, within the operation regime, of reflectivity and transmission of the optical components most relevant to security.Comment: 18 pages, 11 figures. Some typos correcte
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