157 research outputs found

    Cable-Stay Bridge Construction and Progress

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    This presentation will focus on the I-65 cable-stay bridge construction on the Ohio River Bridges Louisville Downtown Crossing project. The presentation will include the overall bridge progress to date, as well as some project issues, including design, construction, and material procurement challenges addressed by the project team

    A study of the hormone effects on tomatoes grown in nitrogen rich soil

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    Call number: LD2668 .T4 1953 P35Master of Scienc

    Altimetric system: Earth observing system. Volume 2h: Panel report

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    A rationale and recommendations for planning, implementing, and operating an altimetric system aboard the Earth observing system (Eos) spacecraft is provided. In keeping with the recommendations of the Eos Science and Mission Requirements Working Group, a complete altimetric system is defined that is capable of perpetuating the data set to be derived from TOPEX/Poseidon, enabling key scientific questions to be addressed. Since the scientific utility and technical maturity of spaceborne radar altimeters is well documented, the discussion is limited to highlighting those Eos-specific considerations that materially impact upon radar altimetric measurements

    Pennsylvania Folklife Vol. 37, No. 1

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    • Franklin in Fact and Fiction: The Double Perspective of Leland Baldwin • Jost Hite: From the Neckar to the Shenandoah • The Migration and Settlement of Pennsylvania Germans in Maryland, Virginia and North Carolina and Their Effects on the Landscape • Bethesda Evangelical Church in Farmers Mills: Fact and Folklore • The Tourist Bureau Shuns Me!https://digitalcommons.ursinus.edu/pafolklifemag/1117/thumbnail.jp

    Swift panchromatic observations of the bright gamma-ray burst GRB050525a

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    The bright gamma-ray burst GRB050525a has been detected with the Swift observatory, providing unique multiwavelength coverage from the very earliest phases of the burst. The X-ray and optical/UV afterglow decay light curves both exhibit a steeper slope ~0.15 days after the burst, indicative of a jet break. This jet break time combined with the total gamma-ray energy of the burst constrains the opening angle of the jet to be 3.2 degrees. We derive an empirical `time-lag' redshift from the BAT data of z_hat = 0.69 +/- 0.02, in good agreement with the spectroscopic redshift of 0.61. Prior to the jet break, the X-ray data can be modelled by a simple power law with index alpha = -1.2. However after 300 s the X-ray flux brightens by about 30% compared to the power-law fit. The optical/UV data have a more complex decay, with evidence of a rapidly falling reverse shock component that dominates in the first minute or so, giving way to a flatter forward shock component at later times. The multiwavelength X-ray/UV/Optical spectrum of the afterglow shows evidence for migration of the electron cooling frequency through the optical range within 25000 s. The measured temporal decay and spectral indices in the X-ray and optical/UV regimes compare favourably with the standard fireball model for Gamma-ray bursts assuming expansion into a constant density interstellar medium.Comment: 31 pages, 7 figures, referee comments implemented, typo corrected in author list, accepted by Ap

    The effect of slip variability on earthquake slip-length scaling

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    There has been debate on whether average slip D in long ruptures should scale with rupture length L, or with rupture width W. This scaling discussion is equivalent to asking whether average stress drop Δσ, which is sometimes considered an intrinsic frictional property of a fault, is approximately constant over a wide range of earthquake sizes. In this paper, we examine slip-length scaling relations using a simplified 1-D model of spatially heterogeneous slip. The spatially heterogeneous slip is characterized by a stochastic function with a Fourier spectrum that decays as k^(−α), where k is the wavenumber and α is a parameter that describes the spatial smoothness of slip. We adopt the simple rule that an individual earthquake rupture consists of only one spatially continuous segment of slip (i.e. earthquakes are not generally separable into multiple disconnected segments of slip). In this model, the slip-length scaling relation is intimately related to the spatial heterogeneity of the slip; linear scaling of average slip with rupture length only occurs when α is about 1.5, which is a relatively smooth spatial distribution of slip. We investigate suites of simulated ruptures with different smoothness, and we show that faults with large slip heterogeneity tend to have higher D/L ratios than those with spatially smooth slip. The model also predicts that rougher faults tend to generate larger numbers of small earthquakes, whereas smooth faults may have a uniform size distribution of earthquakes. This simple 1-D fault model suggests that some aspects of stress drop scaling are a consequence of whatever is responsible for the spatial heterogeneity of slip in earthquakes

    Gamma-Ray Observations of a Giant Flare from The Magnetar SGR 1806-20

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    Magnetars comprise two classes of rotating neutron stars (Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars), whose X-ray emission is powered by an ultrastrong magnetic field, B ~ 10^15 G. Occasionally SGRs enter into active episodes producing many short X-ray bursts; extremely rarely (about once per 50 years per source), SGRs emit a giant flare, an event with total energy at least 1000 times higher than their typical bursts. Here we report that, on 2004 December 27, SGR 1806-20 emitted the brightest extra-solar transient event ever recorded, even surpassing the full moon brightness for 0.2 seconds. The total (isotropic) flare energy is 2x10^46 erg, 100 times higher than the only two previous events, making this flare a once in a century event. This colossal energy release likely occurred during a catastrophic reconfiguration of the magnetar's magnetic field. Such an event would have resembled a short, hard Gamma Ray Burst (GRB) if it had occurred within 40 Mpc, suggesting that extragalactic SGR flares may indeed form a subclass of GRBs.Comment: Submitted to Nature 2005-02-02, revised 2005-03-01. 21 pp, incl. 6 figure

    Riparian and microhabitat factors determine the structure of the EPT community in Andean headwater rivers of Ecuador

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    "This is the peer reviewed version of the following article: Vimos-Lojano, D.J., F. Martínez-Capel, and H. Hampel. 2017. Riparian and Microhabitat Factors Determine the Structure of the EPT Community in Andean Headwater Rivers of Ecuador. Ecohydrology 10 (8). Wiley: e1894. doi:10.1002/eco.1894, which has been published in final form at https://doi.org/10.1002/eco.1894. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving."[EN] This research was conducted in the high-Andean basin of the Zhurucay River in southern Ecuador. In 4 river reaches, 19 sampling campaigns were conducted per reach spread over a period of 35months. The biotic samples were selected in the periods with greatest flow stability. Parallel to each sampling, 37 environmental variables grouped into 3 factors (riparian corridor, hydromorphology, and water quality) were recorded. The study aimed to analyse during periods of stable flow the influence of these environmental factors on the structure and density of the EPT community (Ephemeroptera, Plecoptera, Trichoptera) in a quasi-pristine aquatic ecosystem. Multivariate statistical analysis revealed that the Froude number, gravel type, and width/depth ratio are the most relevant hydromorphological variables explaining variations in EPT density. Xiphocentronidae, Contulma, and Helicopsyche were observed to have a relationship with the order of the river, while Ochrotrichia, Nectopsyche, and Phylloicus varied with the type of riparian vegetation. Phylloicus, Ochrotrichia, and Nectopsyche were common in lentic sites, while the proportion of gravel and the width/depth ratio restricted the genus Helicopsyche. The only relevant water quality factor was the total phosphorus, which was related with 2 taxa. In conclusion, although macroinvertebrates are currently employed in water quality studies, riparian vegetation and hydromorphological factors are determinant for their communities in pristine Andean rivers. Such factors are therefore crucial in the study of environmental flows and the assessment of the ecological integrity.This research was funded by the SENESCYTPIC 11-726 Project (Interpretation of hydro-ecological processes as a basis for assessing the ecological flow in the Paute and Jubones watershed), the hydroelectric company CELECEP, and DIUC (Investigation Department of the University of Cuenca). Thanks are due to the SENESCYT project PIC 11-715 (Impact of land use change in the hydrogeochemistry of Andean basins) for providing the hydrological data used in this study. Further, financial support was provided by SENESCYT through a fellowship granted to the first author for carrying out his doctoral programme and through the PROMETEO fellowship awarded to the third author. 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    A short gamma-ray burst apparently asssociated with an elliptical galaxy at redshift z=0.225

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    Gamma Ray Bursts (GRBs) are bright, brief flashes of high energy photons that have fascinated scientists for 30 years. They come in two classes: long (>2 s), softspectrum bursts and short, hard events. The major progress to date on understanding GRBs has been for long bursts which are typically at high redshift (z ~ 1) and are in sub-luminous star-forming host galaxies. They are likely produced in core-collapse explosions of massive stars. Until the present observation, no short GRB had been accurately (<10") and rapidly (minutes) located. Here we report the detection of X-ray afterglow from and the localization of short burst GRB050509b. Its position on the sky is near a luminous, non-starforming elliptical galaxy at a redshift of 0.225, exactly the type of location one would expect if the origin of this GRB is the long-proposed fiery merger of neutron star (NS) or black hole (BH) binaries. The X-ray afterglow is found to be weak and fading below detection within a few hours and no optical afterglow is detected to stringent limits, explaining the past difficulty in localizing short GRBs.Comment: 16 pages, 3 figures updated figure
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