2,363 research outputs found

    Scientific publications and presentations relating to planetary quarantine. Volume 5: The 1971 supplement

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    A bibliographic compilation, with approximately 200 listings, on planetary quarantine is presented. Also given are scientific publications, and presentations along with an author index

    Can You Quantumfy That?

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    Current educational practices are based upon the science of Newtonian or classical physics. This approach is flawed in that it is an inappropriate method to look at human, social, and dynamic systems

    Momentum-Resolved Ultrafast Electron Dynamics in Superconducting Bi2Sr2CaCu2O8+delta

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    The non-equilibrium state of the high-Tc superconductor Bi2Sr2CaCu2O8+delta and its ultrafast dynamics have been investigated by femtosecond time- and angle-resolved photoemission spectroscopy well below the critical temperature. We probe optically excited quasiparticles at different electron momenta along the Fermi surface and detect metastable quasiparticles near the antinode. Their decay through e-e scattering is blocked by a phase space restricted to the nodal region. The lack of momentum dependence in the decay rates is in agreement with relaxation dominated by Cooper pair recombination in a boson bottleneck limit

    EFFECT OF RECREATIONAL TRAIL TRAFFIC LEVEL ON EASTERN RED-BACKED SALAMANDER (PLETHODON CINEREUS) RELATIVE ABUNDANCE

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    The effects of roads and trails on terrestrial salamanders, primarily plethodontids, can be important. The abundance of terrestrial salamanders often increases with distance from roads. Less is known about the effects of recreational or hiking trails on terrestrial salamanders than is known about the effects of roads. We explored how low and high traffic trails in a suburban biological reserve affect the relative abundance of Eastern Red-backed Salamanders (Plethodon cinereus). We found more salamanders under cover objects next to low traffic trails compared to either high traffic trails or wooded areas without trails. At wooded sites, we found only striped morphs whereas at high traffic sites we found only unstriped morphs. Low traffic sites included a range of color morph frequencies. The proportion of females found in each site did not differ, nor did the mean size of the salamanders. Our results suggest that the impact of recreational walking trails needs to be examined more closely to see how and why the distributions of P. cinereus, and potentially other woodland salamanders, are affected and what trail characteristics are important in driving the apparent effects. Such information will contribute to the design and maintenance of walking trails in natural areas that minimize effects on terrestrial salamanders, and likely other organisms

    Electron-phonon coupling in 122 Fe pnictides analyzed by femtosecond time-resolved photoemission

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    Based on results from femtosecond time-resolved photoemission, we compare three different methods for determination of the electron-phonon coupling constant {\lambda} in Eu and Ba-based 122 FeAs compounds. We find good agreement between all three methods, which reveal a small {\lambda} < 0.2. This makes simple electron-phonon mediated superconductivity unlikely in these compounds.Comment: 11 pages, 3 figure

    Momentum dependent ultrafast electron dynamics in antiferromagnetic EuFe2As2

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    Employing the momentum-sensitivity of time- and angle-resolved photoemission spectroscopy we demonstrate the analysis of ultrafast single- and many-particle dynamics in antiferromagnetic EuFe2As2. Their separation is based on a temperature-dependent difference of photo-excited hole and electron relaxation times probing the single particle band and the spin density wave gap, respectively. Reformation of the magnetic order occurs at 800 fs, which is four times slower compared to electron-phonon equilibration due to a smaller spin-dependent relaxation phase space

    Effects of Age and Group Size on Habitat Selection and Activity Level in \u3ci\u3eXenopus Laevis\u3c/i\u3e Tadpoles

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    We experimentally examined the effects of age and group size on habitat selection and activity level in Xenopus laevis tadpoles. Tadpoles were introduced into an experimental arena at two ages (early and late) and at three group sizes (one, two, and six tadpoles). Group size did not affect habitat selection or activity level. Late tadpoles were more active and used the bottom of the arena more than early tadpoles. Our results suggest that an intrinsic cue (age) is important in determining the behavior of these tadpoles
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