Vibrio cholerae Pathogenic Clones

We resolved the relationships between 2 pandemic clones of Vibrio cholerae. Using 26 housekeeping genes, we showed that the US Gulf clone, the Australian clone, and 3 El Tor strains isolated before the seventh pandemic were related to the seventh pandemic clone. The sixth pandemic clone was well separated from them

Global sausage oscillation of solar flare loops detected by the Interface Region Imaging Spectrograph

An observation from the Interface Region Imaging Spectrograph reveals coherent oscillations in the loops of an M1.6 flare on 2015 March 12. Both the intensity and Doppler shift of Fe xxi 1354.08 Å show clear oscillations with a period of ˜25 s. Remarkably similar oscillations were also detected in the soft X-ray flux recorded by the Geostationary Operational Environmental Satellites (GOES). With an estimated phase speed of ˜2420 km s-1 and a derived electron density of at least 5.4 × 1010cm-3, the observed short-period oscillation is most likely the global fast sausage mode of a hot flare loop. We find a phase shift of ˜π/2 (1/4 period) between the Doppler shift oscillation and the intensity/GOES oscillations, which is consistent with a recent forward modeling study of the sausage mode. The observed oscillation requires a density contrast between the flare loop and coronal background of a factor ≥42. The estimated phase speed of the global mode provides a lower limit of the Alfvén speed outside the flare loop. We also find an increase of the oscillation period,which might be caused by the separation of the loop footpoints with time.PostprintPeer reviewe

Long-Term Exposure of Sitka Spruce Seedlings to Trichloroacetic Acid

Trichloroacetic acid (TCA) has been implicated as an airborne pollutant responsible for adverse effects on forest health. There is considerable debate as to whether TCA observed in trees and forest soils is derived from atmospheric deposition or from in situ production. This experiment reports the results from treating 4-year-old Sitka spruce ( Picea sitchensis(Bong.) Carr) plants in a greenhouse over a growing season with TCA supplied either to the soil or to the foliage at concentrations of 10 and 100 ng mL-1. Similar uptake of TCA by needles was observed for both modes of treatment, with significant accumulation of TCA (300 ng g-1 dry wt) at the higher concentration. Larger concentrations in stem tissue were seen for the foliar-applied TCA (280 ng g-1) than for the soil-applied TCA (70 ng g-1), suggesting that direct stem uptake may be important. Six months after treatments stopped, TCA concentrations in the needles of plants exposed to 100 ng mL-1 TCA were still enhanced, showing that biological degradation of TCA in needles was slow over the winter. By contrast, no significant enhancement of TCA in soil could be detected in the directly treated soils even during the experiment. The protein content of needles treated with the higher concentration of TCA by either route was significantly smaller than for the controls, but there was no effect of TCA on the conjugation of 1-chloro-2,4-dinitrobenzene in roots nor on the conjugation of 1,2-dichloro-4-nitrobenzene in needles

Evaluating lithium diffusion mechanisms in the complex spinel Li2NiGe3O8

Lithium-ion diffusion mechanisms in the complex spinel Li2NiGe3O8 have been investigated using solid-state NMR, impedance, and muon spectroscopies. Partial occupancy of migratory interstitial 12d sites is shown to occur at lower temperatures than previously reported. Bulk activation energies for Li+ ion hopping range from 0.43 ± 0.03 eV for powdered samples to 0.53 ± 0.01 eV for samples sintered at 950 °C for 24 h, due to the loss of Li during sintering at elevated temperatures. A lithium diffusion coefficient of 3.89 × 10−12 cm2 s−1 was calculated from muon spectroscopy data for Li2NiGe3O8 at 300 K

North Atlantic right whales (Eubalaena glacialis) ignore ships but respond to alerting stimuli

Author Posting. © Royal Society, 2004. This article is posted here by permission of Royal Society for personal use, not for redistribution. The definitive version was published in Proceedings of the Royal Society of London B 271 (2004): 227-231, doi:10.1098/rspb.2003.2570.North Atlantic right whales were extensively hunted during the whaling era and have not recovered. One of the primary factors inhibiting their recovery is anthropogenic mortality caused by ship strikes. To assess risk factors involved in ship strikes, we used a multi-sensor acoustic recording tag to measure the responses of whales to passing ships and experimentally tested their responses to controlled sound exposures, which included recordings of ship noise, the social sounds of conspecifics and a signal designed to alert the whales. The whales reacted strongly to the alert signal, they reacted mildly to the social sounds of conspecifics, but they showed no such responses to the sounds of approaching vessels as well as actual vessels. Whales responded to the alert by swimming strongly to the surface, a response likely to increase rather than decrease the risk of collision.Funding for this work was provided by the Fisheries Service of the US National Oceanic and Atmospheric Administration (contract no. NA87RJ0445), and was conducted under NOAA Fisheries permit to conduct scientific research no. 1014 issued to Dr Scott Kraus and Canadian Department of Fisheries and Oceans permits 2001-559 and 2002-568

The X-ray Afterglows of GRB 020813 and GRB 021004 with Chandra HETGS: Possible Evidence for a Supernova Prior to GRB 020813

We report on the detection of an emission line near 1.3 keV, which we associate with blue-shifted hydrogen-like sulfur (S XVI), in a 76.8 ksec Chandra HETGS spectrum of the afterglow of GRB 020813. The line is detected at 3.3 sigma significance. We also find marginal evidence for a line possibly due to hydrogen-like silicon (Si XIV) with the same blue-shift. A line from Fe is not detected, though a very low significance Ni feature may be present. A thermal model fits the data adequately, but a reflection model may provide a better fit. There is marginal evidence that the equivalent width of the S XVI line decrease as the burst fades. We infer from these results that a supernova likely occurred >~ 2 months prior to the GRB. We find no discrete or variable spectral features in the Chandra HETGS spectrum of the GRB 021004 afterglow.Comment: 26 pages, 11 figures, submitted to Ap