19,301 research outputs found

    Contemporary Seismicity in and Around the Yakima Fold-and-Thrust Belt in Eastern Washington

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    We examined characteristics of routinely cataloged seismicity from 1970 to the present in and around the Yakima fold-and-thrust belt (YFTB) in eastern Washington to determine if the characteristics of contemporary seismicity provide clues about regional-scale active tectonics or about more localized, near-surface processes. We employed new structural and hydrologic models of the Columbia River basalts (CRB) and found that one-third to one-half of the cataloged earthquakes occur within the CRB and that these CRB earthquakes exhibit significantly more clustered, and swarmlike, behavior than those outside. These results and inferences from published studies led us to hypothesize that clustered seismicity is likely associated with hydrologic changes in the CRB, which hosts the regional aquifer system. While some general features of the regional groundwater system support this hypothesis, seismicity patterns and mapped long-term changes in groundwater levels and present-day irrigation neither support nor refute it. Regional tectonic processes and crustal-scale structures likely influence the distribution of earthquakes both outside and within the CRB as well. We based this inference on qualitatively assessed alignments between the dominant northwest trends in the geologic structure and the seismicity generally and between specific faults and characteristics of the 2009 Wooded Island swarm and aseismic slip, which is the only cluster studied in detail and the most vigorous since regional monitoring began.USGS-NAGTGeological Science

    Cluster Winds Blow along Supercluster Axes

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    Within Abell galaxy clusters containing wide-angle tailed radio sources, there is evidence of a ``prevailing wind'' which directs the WAT jets. We study the alignment of WAT jets and nearby clusters to test the idea that this wind may be a fossil of drainage along large-scale supercluster axes. We also test this idea with a study of the alignment of WAT jets and supercluster axes. Statistical test neighbours indicate no alignment of WAT jets towards nearest clusters, but do indicate approximately 98% confidence in alignment with the long axis of the supercluster in which the cluster lies. We find a preferred scale for such superclusters of order 25 Mpc h1h^{-1}.Comment: Latex, 5 pages, with 5 postscript figures. To be published in MNRAS. Slight revisions to coincide with journal text. Linked to color image at http://kusmos.phsx.ukans.edu/~melott/images/A2634SUW.jp

    The low frequency cutoff of ELF emissions

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    Extremely low and very low frequency radio noises observed by satellites in ionospher

    The low frequency cutoff of ELF emissions Progress report, May 1968

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    Low frequency cutoff of extremely low radio frequency emission

    Pencil-Beam Surveys for Faint Trans-Neptunian Objects

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    We have conducted pencil-beam searches for outer solar system objects to a limiting magnitude of R ~ 26. Five new trans-neptunian objects were detected in these searches. Our combined data set provides an estimate of ~90 trans-neptunian objects per square degree brighter than ~ 25.9. This estimate is a factor of 3 above the expected number of objects based on an extrapolation of previous surveys with brighter limits, and appears consistent with the hypothesis of a single power-law luminosity function for the entire trans-neptunian region. Maximum likelihood fits to all self-consistent published surveys with published efficiency functions predicts a cumulative sky density Sigma(<R) obeying log10(Sigma) = 0.76(R-23.4) objects per square degree brighter than a given magnitude R.Comment: Accepted by AJ, 18 pages, including 6 figure

    On equivariant characteristic ideals of real classes

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    Let pp be an odd prime, F/QF/{\Bbb Q} an abelian totally real number field, F/FF_\infty/F its cyclotomic Zp{\Bbb Z}_p-extension, G=Gal(F/Q),G_\infty = Gal (F_\infty / {\Bbb Q}), A=Zp[[G]].{\Bbb A} = {\Bbb Z}_p [[G_\infty]]. We give an explicit description of the equivariant characteristic ideal of HIw2(F,Zp(m))H^2_{Iw} (F_\infty, {\Bbb Z}_p(m)) over A{\Bbb A} for all odd mZm \in {\Bbb Z} by applying M. Witte's formulation of an equivariant main conjecture (or "limit theorem") due to Burns and Greither. This could shed some light on Greenberg's conjecture on the vanishing of the λ\lambda-invariant of $F_\infty/F.

    Physical and Strength Characteristics of College Lacrosse Players in Relation to Player Role

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    Please refer to the pdf version of the abstract located adjacent to the title

    Freezing properties of alkenyl succinic anhydrides derived from linear isomerised olefins

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    Alkenyl succinic anhydrides are important specialty chemicals that are used in the paper, oilfield and fuel additives industries. In this paper we investigate the link between the physical properties of alkenyl succinic anhydrides and the identities of their linear alkyl olefin precursors. We describe a straightforward GC analysis of olefin isomer distributions and show that these correlate well with the freezing temperatures of the subsequent alkenyl succinic anhydride products. This allows the identification of olefin isomer profiles that are required to give the desired physical properties in the alkenyl succinic anhydrides; it also provides a method to predict the freezing temperatures of alkenyl succinic anhydrides synthesised from a particular supply of olefin
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