41,168 research outputs found

    Scanning nozzle plating system

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    A plating system is described in which a substrate to be plated is supported on a stationary platform. A nozzle assembly with a small nozzle is supplied with a plating solution under high pressure, so that a constant-flow stream of solution is directed to the substrate. The nozzle assembly is moved relative to the substrate at a selected rate and movement pattern. A potential difference (voltage) is provided between the substrate and the solution in the assembly. The voltage amplitude is modulated so that only when the amplitude is above a minimum known value plating takes place

    Wavelet analysis of the seismograms of the 2004 Sumatra-Andaman earthquake and its application to tsunami early warning

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    We applied the wavelet transform in an attempt to detect long-period components early in a seismogram. We analyzed the displacement seismograms of the 26 December 2004 Sumatra-Andaman earthquake (Mw = 9.2) and the 28 March 2005 Nias earthquake (Mw = 8.7). Wavelet analysis is able to clearly distinguish the amplitudes of the long-period W phase between the seismograms of the two earthquakes before the S wave reaches the station. It shows that the 2004 earthquake generates a W phase of significantly greater amplitude. This facility has potential application to the rapid identification of truly great earthquakes with high tsunami potential

    Forecasts for Low Spin Black Hole Spectroscopy in Horndeski Gravity

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    We investigate the prospect of using black hole spectroscopy to constrain the parameters of Horndeski gravity through observations of gravitational waves from perturbed black holes. We study the gravitational waves emitted during ringdown from black holes without hair in Horndeski gravity, demonstrating the qualitative differences between such emission in General Relativity and Horndeski theory. In particular, Quasi-Normal Mode frequencies associated with the scalar field spectrum can appear in the emitted gravitational radiation. Analytic expressions for error estimates for both the black hole and Horndeski parameters are calculated using a Fisher Matrix approach, with constraints on the `effective mass' of the Horndeski scalar field of order ∌10−17\sim 10^{-17}eVc−2c^{-2} or tighter being shown to be achievable in some scenarios. Estimates for the minimum signal-noise-ratio required to observe such a signal are also presented.Comment: Updated to match published versio

    Spitzer IRS observations of k plus a galaxies: a link between polycyclic aromatic hydrocarbon emission properties and active galactic nucleus feedback?

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    We have performed Spitzer InfraRed Spectrograph (IRS) low-resolution 5-12 mu m spectroscopy on a sample of galaxies selected to be at three distinct poststarburst evolutionary stages based on their optical spectral indices. The resulting IRS spectra show distinctive polycyclic aromatic hydrocarbon (PAH) emission line structures at 6.2, 7.7, 8.6, and 11.3 mu m and little silicate absorption, indicative of ongoing star formation. However, the PAH interline ratios, in particular the 11.3/6.2 mu m and 7.7/6.2 mu m ratio, show large variations. These variations are found to correlate with both time since the most recent starburst and active galactic nucleus (AGN) activity. We speculate that the evolution observed in these PAH ratios is related to an increase in AGN activity with time since starburst

    Improved bounds on the set A(A+1)

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    For a subset A of a field F, write A(A + 1) for the set {a(b + 1):a,b\in A}. We establish new estimates on the size of A(A+1) in the case where F is either a finite field of prime order, or the real line. In the finite field case we show that A(A+1) is of cardinality at least C|A|^{57/56-o(1)} for some absolute constant C, so long as |A| < p^{1/2}. In the real case we show that the cardinality is at least C|A|^{24/19-o(1)}. These improve on the previously best-known exponents of 106/105-o(1) and 5/4 respectively
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