47,127 research outputs found

    Instanton-Induced Interactions in Finite Density QCD

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    We consider the finite density, zero-temperature behaviour of quark matter in the instanton picture. Since the instanton-induced interactions are attractive in both qˉq\bar{q}q and qqqq channels, a competition ensues between phases of matter with condensation in either or both. It results in chiral symmetry restoration due to the onset of diquark condensation, a `colour superconductor', at finite density.Comment: 4 pages, 5 figures, uses espcrc1.sty. To appear in Proceedings of Quark Matter 99 (10-14 May 1999, Torino, Italy) and PANIC 99 (10-16 June 1999, Uppsala, Sweden

    Signal processing at the Poker Flat MST radar

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    Signal processing for Mesosphere-Stratosphere-Troposphere (MST) radar is carried out by a combination of hardware in high-speed, special-purpose devices and software in a general-purpose, minicomputer/array processor. A block diagram of the signal processing system is presented, and the steps in the processing pathway are described. The current processing capabilities are given, and a system offering greater coherent integration speed is advanced which hinges upon a high speed preprocessor

    The effects of pulse rate, power, width and coding on signal detectability

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    The effects on the signal detectability of varying the pulse repetition rate (PRF), peak pulse power (p(pk)) and pulse width (tau(p)) (tp) are examined. Both coded and uncoded pulses are considered. The following quantities are assumed to be constant; (1) antenna area, (z)echo reflectivity, (3) Doppler shift, (4) spectral width, (5) spectral resolution, (6) effective sampling rate, and (7) total incoherent spectral averagaing time. The detectability is computed for two types of targets

    Discrimination against interfering signals at the Poker Flat MST radar

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    Several on line and off line data processing techniques are used to remove interfering signals due to ground clutter, aircraft, instrumental effects, and external transmissions from the desired atmospheric echoes of Mesosphere Stratosphere, Troposphere (MST) radar. The on line, real time techniques are necessarily simple in order to minimize processing delays. This algorithm examines the individual Doppler spectra which are computed every two to four seconds (for oblique antenna beams). The total spectral power in each individual spectrum is computed by summing all the spectral points. If this integrated power increases from one spectrum to the next by a factor greater than a preselected threshold, then that spectrum is not added to the spectral sum. Succeeding spectra are compared to the last acceptable spectrum. Only a certain maximum number of spectra are allowed to be rejected in succession

    Social medicine and international expert networks in Latin America, 1930–1945

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    This paper examines the international networks that influenced ideas and policy in social medicine in the 1930s and 1940s in Latin America, focusing on institutional networks organised by the League of Nations Health Organization, the International Labour Organization, and the Pan-American Sanitary Bureau. After examining the architecture of these networks, this paper traces their influence on social and health policy in two policy domains: social security and nutrition. Closer scrutiny of a series of international conferences and local media accounts of them reveals that international networks were not just ‘conveyor belts’ for policy ideas from the industrialised countries of the US and Europe into Latin America; rather, there was often contentious debate over the relevance and appropriateness of health and social policy models in the Latin American context. Recognition of difference between Latin America and the global economic core regions was a key impetus for seeking ‘national solutions to national problems’ in countries like Argentina and Chile, even as integration into these networks provided progressive doctors, scientists, and other intellectuals important international support for local political reforms

    Coherent manipulation of cold Rydberg atoms near the surface of an atom chip

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    Coherent superpositions of the 49s and 48s Rydberg states of cold Rb atoms were studied near the surface of an atom chip. The superpositions were created and manipulated using microwaves resonant with the two-photon 49s-48s transition. Coherent behavior was observed using Rabi flopping, Ramsey sequences, spin-echo and spin-locking. These results are discussed in the context of Rydberg atoms as electric field noise sensors. We consider the coherence of systems quadratically coupled to noise fields with 1/f^k power spectral densities (k \approx 1).Comment: 11 pages, 7 figure

    Summary of significant results of remote sensing studies in 1965

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    Technology survey on remote sensors mounted in earth orbiting spacecraf

    Evaluation of ERTS-1 data applications to geologic mapping, structural analysis and mineral resource inventory of South America with special emphasis on the Andes Mountain region

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    The author has identified the following significant results. The La Paz Mosaic and its attendant overlays serve as a model for geologic studies elsewhere in the world. The P.I. and two geologists are mapping the conterminous states at scales of 1:5000,000 and 1:1,000,000. The 1:5 million band 5 mosaic was completed in two days of analysis. The 1:1 million band sheets are being completed at the rate of one per day. Comparison of the preliminary results of the three investigators shows a high correlation of linear and curvilinear features. Comparison with magnetic and gravity data indicates that many features being mapped are deep seated structures that have been active through long periods of geologic time, perhaps dating back to the Precambrian period. A detailed analysis of the El Salvador mining district has been completed. The interpretation is extremely detailed showing a complex pattern of linear features and bedrock outcrop patterns. This is the first product from ERTS-1 to be provided by Chile and shows a high degree of expertise in image interpretation. The Chileans are enthusiastic about their results and are anxious to map the entire country using ERTS
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