455 research outputs found

    Wireless monitoring of internal wound roll pressures

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    Winding is a dynamic process. The final roll is the product of all that happens during the winding process from roll start to final cutoff. Nearly all roll measurement methods try to characterize a roll's structure after winding is completed, like understanding why a plane crashes from diagnosis of the debris. What winding needs is the equivalent of a 'black box,' a monitoring device to record the dynamic nature of the winding process. Using thin resistance-based pressure sensors and wireless data collection, we will show the changes inside a winding roll as a function of key winding variable, including product properties, winding torque and nip loads, winding speed, and rotation position

    In Situ Digestibility of Residue Parts of Corn Planted in Different Populations and Row Widths

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    Plant density can be changed by altering row width and/or number of plants within a row. The use of narrower rows at seeding may increase yield and reduce plant-toplant competition. Corn seeds were planted at 2 row widths (15 and 30- inch rows) and 3 plant populations (25,200, 35,000 and 54,000 seeds / acre). Samples of corn residue were collected 4 dates (October 8, October 24, November 5 and November 19) postharvest and separated into cob, stem, leaf and husk to determine changes in quality over time. Th e greatest plant population increased the NDF content and NDF digestibility of husk, NDF and true digestibilities of cob, NDF content of stem, and decreased the true digestibility of the stem. The NDF content of the leaves and stem increased over time while the NDF and true digestibilities of cob decreased over time. Row width did not affect the corn residue. Planting densities and management strategies can affect the digestibility of leaf and husk and may impact residue quality

    The bright optical/NIR afterglow of the faint GRB 080710 - Evidence for a jet viewed off axis

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    We investigate the optical/near-infrared light curve of the afterglow of GRB 080710 in the context of rising afterglows. Optical and near-infrared photometry was performed using the seven channel imager GROND and the Tautenburg Schmidt telescope. X-ray data were provided by the X-ray Telescope onboard the Swift satellite. The optical/NIR light curve of the afterglow of GRB 080710 is dominated by an initial increase in brightness, which smoothly turns over into a shallow power law decay. The initially rising achromatic light curve of the afterglow of GRB 080710 can be accounted for with a model of a burst viewed off-axis or a single jet in its pre deceleration phase and in an on-axis geometry. An unified picture of the afterglow light curve and prompt emission properties can be obtained with an off-axis geometry, suggesting that late and shallow rising optical light curves of GRB afterglows might be produced by geometric effects.Comment: 9 pages, 4 figures, accepted by A and

    GRB 091127: The cooling break race on magnetic fuel

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    Using high-quality, broad-band afterglow data for GRB 091127, we investigate the validity of the synchrotron fireball model for gamma-ray bursts, and infer physical parameters of the ultra-relativistic outflow. We used multi-wavelength follow-up observations obtained with GROND and the XRT onboard the Swift satellite. The resulting afterglow light curve is of excellent accuracy, and the spectral energy distribution is well-sampled over 5 decades in energy. These data present one of the most comprehensive observing campaigns for a single GRB afterglow and allow us to test several proposed emission models and outflow characteristics in unprecedented detail. Both the multi-color light curve and the broad-band SED of the afterglow of GRB 091127 show evidence of a cooling break moving from high to lower energies. The early light curve is well described by a broken power-law, where the initial decay in the optical/NIR wavelength range is considerably flatter than at X-rays. Detailed fitting of the time-resolved SED shows that the break is very smooth with a sharpness index of 2.2 +- 0.2, and evolves towards lower frequencies as a power-law with index -1.23 +- 0.06. These are the first accurate and contemporaneous measurements of both the sharpness of the spectral break and its time evolution. The measured evolution of the cooling break (nu_c propto t^-1.2) is not consistent with the predictions of the standard model, wherein nu_c propto t^-0.5 is expected. A possible explanation for the observed behavior is a time dependence of the microphysical parameters, in particular the fraction of the total energy in the magnetic field epsilon_B. This conclusion provides further evidence that the standard fireball model is too simplistic, and time-dependent micro-physical parameters may be required to model the growing number of well-sampled afterglow light curves.Comment: accepted to A&A, 13 pages, 5 figure

    Effect of Corn Residue Harvest Method on In Vivo and In Vitro Digestibility

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    A digestion study was conducted using 18 crossbred wether lambs to evaluate the effects of corn residue harvesting method and ensiling on the digestibility of corn residue. Husks had the greatest digestibility compared to any of the harvesting methods. No differences were observed for the digestibility of husklage, ensiled husklage, or stalklage. None of the harvest methods resulted in residue digestibilities similar to husks

    The late-time afterglow of the extremely energetic short burst GRB 090510 revisited

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    The discovery of the short GRB 090510 has raised considerable attention mainly because it had a bright optical afterglow and it is among the most energetic events detected so far within the entire GRB population. The afterglow was observed with swift/UVOT and swift/XRT and evidence of a jet break around 1.5 ks after the burst has been reported in the literature, implying that after this break the optical and X-ray light curve should fade with the same decay slope. As noted by several authors, the post-break decay slope seen in the UVOT data is much shallower than the steep decay in the X-ray band, pointing to an excess of optical flux at late times. We reduced and analyzed new afterglow light-curve data obtained with the multichannel imager GROND. Based on the densely sampled data set obtained with GROND, we find that the optical afterglow of GRB 090510 did indeed enter a steep decay phase starting around 22 ks after the burst. During this time the GROND optical light curve is achromatic, and its slope is identical to the slope of the X-ray data. In combination with the UVOT data this implies that a second break must have occurred in the optical light curve around 22 ks post burst, which, however, has no obvious counterpart in the X-ray band, contradicting the interpretation that this could be another jet break. The GROND data provide the missing piece of evidence that the optical afterglow of GRB 090510 did follow a post-jet break evolution at late times.Comment: submitted to Astronomy & Astrophysics, accepted for publication on Dec 24, 201

    BL Lacertae objects beyond redshift 1.3 - UV-to-NIR photometry and photometric redshift for Fermi/LAT blazars

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    Observations of the gamma-ray sky with Fermi led to significant advances towards understanding blazars, the most extreme class of Active Galactic Nuclei. A large fraction of the population detected by Fermi is formed by BL Lacertae (BL Lac) objects, whose sample has always suffered from a severe redshift incompleteness due to the quasi-featureless optical spectra. Our goal is to provide a significant increase of the number of confirmed high-redshift BL Lac objects contained in the 2 LAC Fermi/LAT catalog. For 103 Fermi/LAT blazars, photometric redshifts using spectral energy distribution fitting have been obtained. The photometry includes 13 broad-band filters from the far ultraviolet to the near-IR observed with Swift/UVOT and the multi-channel imager GROND at the MPG/ESO 2.2m telescope. Data have been taken quasi-simultaneously and the remaining source-intrinsic variability has been corrected for. We release the UV-to-near-IR 13-band photometry for all 103 sources and provide redshift constraints for 75 sources without previously known redshift. Out of those, eight have reliable photometric redshifts at z>1.3, while for the other 67 sources we provide upper limits. Six of the former eight are BL Lac objects, which quadruples the sample of confirmed high-redshift BL Lac. This includes three sources with redshifts higher than the previous record for BL Lac, including CRATES J0402-2615 with the best-fit solution at z~1.9.Comment: Uploaded correct Fig 4. Changed counterpart name for 2FGLJ0537.7-5716 from PKS 0541-834 (different source) to SUMSS J053748-57182

    Super-solar Metal Abundances in Two Galaxies at z ~ 3.57 revealed by the GRB 090323 Afterglow Spectrum

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    We report on the surprisingly high metallicity measured in two absorption systems at high redshift, detected in the Very Large Telescope spectrum of the afterglow of the gamma-ray burst GRB090323. The two systems, at redshift z =3.5673 and z =3.5774 (separation ∆v ≈ 660 km s−1), are dominated by the neutral gas in the interstellar medium of the parent galaxies. From the singly ionized zinc and sulfur, we estimate oversolar metallicities of [Zn/H] = +0.29± 0.10 and [S/H] = +0.67± 0.34, in the blue and red absorber, respectively. These are the highest metallicities ever measured in galaxies at z\u3e 3. We propose that the two systems trace two galaxies in the process of merging, whose star formation and metallicity are heightened by the interaction. This enhanced star formation might also have triggered the birth of the GRB progenitor. As typically seen in star-forming galaxies, the fine-structure absorption Siii∗ is detected, both in G0 and G1. From the rest-frame UV emission in the GRB location, we derive arelatively high, not corrected for dust extinction, star-formation rate SFR ≈ 6M yr−1. These properties suggest a possible connection between some high-redshift GRB host galaxies and high-z massive sub-millimeter galaxies, which are characterized by disturbed morphologies and high metallicities. Our result provides additional evidence that the dispersion in the chemical enrichment of the Universe at high redshift is substantial, with the existence of very metal rich galaxies less than two billion years after the Big Bang

    Evidence for Supernova-Synthesised Dust from the Rising Afterglow of GRB 071025 at z~5

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    We present observations and analysis of the broadband afterglow of Swift GRB 071025. Using optical and infrared (RIYJHK) photometry, we derive a photometric redshift of 4.4 < z < 5.2; at this redshift our simultaneous multicolour observations begin at ~30 s after the GRB trigger in the host frame and during the initial rising phase of the afterglow. We associate the light curve peak at 580 s in the observer frame with the formation of the forward shock, giving an estimate of the initial Lorentz factor Gamma_0 ~ 200. The red spectral energy distribution (even in regions not affected by the Lyman-alpha break) provides secure evidence of a large dust column. However, the inferred extinction curve shows a prominent flat component between 2000-3000 Angstroms in the rest-frame, inconsistent with any locally observed template but well-fit by models of dust formed by supernovae. Time-dependent fits to the extinction profile reveal no evidence of dust destruction and limit the decrease in the extinction column to Delta A_3000 < 0.54 mag after t = 50 s in the rest frame. Our observations provide evidence of a transition in dust properties at z~5, in agreement with studies of high-z quasars, and suggest that SN-formed dust continues to dominate the opacity of typical galaxies at this redshift.Comment: Resubmitted to MNRAS following referee report. Contains additional figure and some extra analysis/discussio

    The Rapidly Flaring Afterglow of the Very Bright and Energetic GRB 070125

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    We report on multiwavelength observations, ranging from X-ray to radio wave bands, of the IPN-localized gamma-ray burst GRB 070125. Spectroscopic observations reveal the presence of absorption lines due to O i,Si ii,and C iv, implying a likely redshift of z ¼1:547. The well-sampled light curves, in particular from 0.5 to 4 days after the burst, suggest a jet break at 3.7 days, corresponding to a jet opening angle of 7.0,andimplyinganintrinsicGRBenergyinthe1Y10,000keVbandofaroundE¼(6:3Y6:9);1051ergs(basedontheuencesmeasuredbythegammaraydetectorsoftheIPN).GRB070125isamongthebrightestafterglowsobservedtodate.TheSEDimpliesahostextinctionofAV3˘c0:9mag.Tworebrighteningepisodesareobserved,onewithexcellenttimecoverage,showinganincreaseinuxof567.0, and implying an intrinsic GRB energy in the 1Y10,000 keV band of around E ¼(6:3Y6:9) ; 1051 ergs (based on the fluences measured by the gamma-ray de-tectorsof the IPN).GRB070125 is among the brightest afterglows observed to date.The SEDimplies ahostextinction of AV \u3c 0:9 mag. Two rebrightening episodes are observed, one with excellent time coverage, showing an increase in fluxof 56% in 8000 s.The evolution of the afterglow light curve is achromatic at all times.Late-time observationsof the afterglow do not show evidence for emission from an underlying host galaxy or supernova. Any host galaxy would be subluminous, consistent with current GRB host galaxy samples. Evidence for strong Mg ii absorption features is not found, which is perhaps surprising in view of the relatively high redshift of this burst and the high likelihood for such features along GRB-selected lines of sight
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