13,968 research outputs found

    Studies of ''soft tooling'' for a semi- toroidal test tank Final report

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    Unfeasibility of soft tooling for semi-toroidal test tan

    Entropy of Contracting Universe in Cyclic Cosmology

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    Following up a recent proposal \cite{BF} for a cyclic model based on phantom dark energy, we examine the content of the contracting universe (cu) and its entropy ScuS_{cu}. We find that beyond dark energy the universe contains on average zero or at most a single photon which if present immediately after turnaround has infinitesimally energy which subsequently blue shifts to produce e+ee^+e^- pairs. These statements are independent of the equation of state ω=p/ρ\omega = p/\rho of dark energy provided ω<1\omega < -1. Thus Scu=0S_{cu} = 0 and if observations confirm ω<1\omega < -1 the entropy problem is solved. We discuss the absence of a theoretical lower bound on ϕ=ω+1\phi = |\omega + 1|, then describe an anthropic fine tuning argument that renders unlikely extremely small ϕ\phi. The present bound ϕ0.1\phi \lesssim 0.1 already implies a time until turnaround of (tTt0)100(t_T - t_0) \gtrsim 100 Gy.Comment: 5 pages late

    Communication to the World Food Conference: Plant Nutrients

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    27 September 1974 letter from CGIAR Chairman Warren C. Baum to World Food Conference Secretary General Sayed Marei on the work being done on plant nutrients at CGIAR centers and proposals being considered by the CGIAR and its TAC. Agenda document presented at CGIAR meeting, October 1974

    CGIAR: How it all Began

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    This report is a brief summary of events leading to the formation of the CGIAR in 1971, as extracted from the the first two chapters of "Partners Against Hunger" by Warren Baum. This summary is also included in the CGIAR's 1985 annual report

    Extended emission around GPS radio sources

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    Extended radio emission detected around a sample of GHz Peaked Spectrum (GPS) radio sources is discussed. Evidence for extended emission which is related to the GPS source is found in 6 objects out of 33. Three objects are associated with quasars with core-jet pc-scale morphology, and three are identified with galaxies with symmetric (CSO) radio morphology. We conclude that the core-jet GPS quasars are likely to be beamed objects with a continuous supply of energy from the core to the kpc scale. It is also possible that low surface brightness extended radio emission is present in other GPS quasars but the emission is below our detection limit due to the high redshifts of the objects. On the other hand, the CSO/galaxies with extended large scale emission may be rejuvenated sources where the extended emission is the relic of previous activity. In general, the presence of large scale emission associated with GPS galaxies is uncommon, suggesting that in the context of the recurrent activity model, the time scale between subsequent bursts is in general longer than the radiative lifetime of the radio emission from the earlier activity.Comment: 18 paged, 18 figures, accepted for publication on A&

    Cryptocurrency Fraud: A Look Into The Frontier of Fraud

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    This research project was conducted to look into what sort of frauds can be committed to steal unsuspecting investors’ cryptocurrencies. The inspiration for this research came in the form of the fact that millions of dollars are lost to cryptocurrency fraud each day, and many of these frauds are successful due to the public’s naivete towards the dangers of investing in cryptocurrencies. After researching many different cryptocurrency fraud cases, the frauds could be categorized into four major categories. These categories include Ponzi schemes, fake initial coin offering schemes, pump and dump schemes as well as cryptocurrency theft

    The Properties and Gaseous Environments of Powerful Classical Double Radio Galaxies

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    The properties of a sample of 31 very powerful classical double radio galaxies with redshifts between zero and 1.8 are studied. The source velocities, beam powers, ambient gas densities, total lifetimes, and total outflow energies are presented and discussed. The rate of growth of each side of each source were obtained using a spectral aging analysis. The beam power and ambient gas density were obtained by applying the strong shock jump conditions to the ends of each side of the source. The total outflow lifetime was obtained by applying the power-law relationship between the beam power and the total source lifetime derived elsewhere for sources of this type, and the total outflow energy was obtained by combining the beam power and the total source lifetime. Composite profiles were constructed by combining results obtained from each side of each source. The composite profiles indicate that the ambient gas density falls with distance from the central engine. The source velocities, beam powers, total lifetimes, and total energies seem to be independent of radio source size. This is consistent with the standard model in which each source grows at a roughly constant rate during which time the central engine puts out a roughly constant beam power. The fact that the total source lifetimes and energies are independent of radio source size indicates that the sources are being sampled at random times during their lifetimes.Comment: 7 pages, 5 figures, to appear in "Extragalactic Jets: Theory and Observation from Radio to Gamma Ray", eds. T. A. Rector and D. S. De Young, ASP conference series, Replaced version has minor textual correction
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