868 research outputs found
Datana drexelii (Lepidoptera: Notododontidae) occurrence and larval survival on highbush blueberry cultivars
Plant genotype influences plant suitability to herbivores; domesticated plants selected for properties such as high fruit yield may be particularly vulnerable to herbivory. Cultivated strains of highbush blueberry, Vaccinium corymbosum L. can be high-quality hosts for larvae of the gregariously-feeding notodontid Datana drexelii (Hy. Edwards). We conducted an experiment assessing D. drexelii larval survival and pupal weight when fed foliage from five blueberry cultivars: âBluecropâ, âBluettaâ, âBluerayâ, âLateblueâ, and âJerseyâ. We complemented this experimental work with repeated bush-level surveys of a managed blueberry patch for naturally occurring D. drexelii larval clusters. Larval survival and pupal weight were significantly higher on âLateblueâ foliage than from the âBluecropâ, âBluettaâ, and âJerseyâ cultivars. The blueberry patch surveys found more D. drexelii larval clusters on âBluehavenâ, âCollinsâ, and âDarrowâ bushes than on the cultivars âEarliblueâ and âJerseyâ. The low D. drexelii occurrence and performance on the âJerseyâ cultivar suggests that this variety may be appropriate for areas where this pest is common; conversely, their high occurrence on âBluehavenâ âCollinsâ, and âDarrowâ suggests that these cultivars may be particularly vulnerable. Cultivar-level variation in herbivore vulnerability highlights how understanding plant-pest interactions can help manage agricultural species
A Field-Test of Rhodamine B as a Biomarker in Raccoons
Rhodamine B is a dye that when ingested results in fluorescent bands in growing hair and whiskers of many mammals. Previous research at Wildlife Servicesâ (WS) National Wildlife Research Center (NWRC) found that rhodamine B is a successful biomarker in raccoon whiskers and that raccoons do not have a taste aversion to the dye when it comprises †3% of a bait. Our study assessed the ease of bait distribution, whisker collection, and evaluation of the biomarker for potential use in the Oral Rabies Vaccination (ORV) program administered by the WS National Rabies Management Program (NRMP). In collaboration with WS operations personnel from Ohio and Michigan, 750 fishmeal polymer baits each containing 150 mg of rhodamine B were hand distributed at NASA\u27s Plum Brook Station, Sandusky, Ohio in the summer of 2008. Four weeks after baits were distributed whiskers from 162 raccoons were collected. Wildlife Services biologists and technicians evaluated the whiskers for fluorescence using a handheld UV magnifying lamp. Biologists then sent the whiskers to the NWRC, Ft. Collins, Colorado for confirmation of fluorescence under a UV microscope. Results suggest a high level of agreement between the two methods of evaluation. Surveys completed by biologists confirmed that the ease of use, less invasive sampling techniques and promptness of results obtained through the use of rhodamine B are advantageous to the tetracycline biomarker presently used by the ORV program. All participants recommended further evaluation of rhodamine B for its inclusion in future efforts requiring biomarker evaluation
Quasi-classical cyclotron resonance of Dirac fermions in highly doped graphene
Cyclotron resonance in highly doped graphene has been explored using infrared
magnetotransmission. Contrary to previous work, which only focused on the
magneto-optical properties of graphene in the quantum regime, here we study the
quasi-classical response of this system. We show that it has a character of
classical cyclotron resonance, with an energy which is linear in the applied
magnetic field and with an effective cyclotron mass defined by the position of
the Fermi level m = E_F/v_F^2.Comment: 6 pages, 4 figure
A new beamline for laser spin-polarization at ISOLDE
A beamline dedicated to the production of laser-polarized radioactive beams
has been constructed at ISOLDE, CERN. We present here different simulations
leading to the design and construction of the setup, as well as technical
details of the full setup and examples of the achieved polarizations for
several radioisotopes. Beamline simulations show a good transmission through
the entire line, in agreement with observations. Simulations of the induced
nuclear spin-polarization as a function of atom-laser interaction length are
presented for Na, [1] and for Ar, which is studied in this
work. Adiabatic spin rotation of the spin-polarized ensemble of atoms, and how
this influences the observed nuclear ensemble polarization, are also performed
for the same nuclei. For Ar, we show that multiple-frequency pumping
enhances the ensemble polarization by a factor 1.85, in agreement with
predictions from a rate equations model.
[1] J. Phys. G: Nucl. Part. Phys./174408400
Versatile transporter apparatus for experiments with optically trapped Bose-Einstein condensates
We describe a versatile and simple scheme for producing magnetically and
optically-trapped Rb-87 Bose-Einstein condensates, based on a moving-coil
transporter apparatus. The apparatus features a TOP trap that incorporates the
movable quadrupole coils used for magneto-optical trapping and long-distance
magnetic transport of atomic clouds. As a stand-alone device, this trap allows
for the stable production of condensates containing up to one million atoms. In
combination with an optical dipole trap, the TOP trap acts as a funnel for
efficient loading, after which the quadrupole coils can be retracted, thereby
maximizing optical access. The robustness of this scheme is illustrated by
realizing the superfluid-to-Mott insulator transition in a three-dimensional
optical lattice
Wannier-function description of the electronic polarization and infrared absorption of high-pressure hydrogen
We have constructed maximally-localized Wannier functions for prototype
structures of solid molecular hydrogen under pressure, starting from LDA and
tight-binding Bloch wave functions. Each occupied Wannier function can be
associated with two paired protons, defining a ``Wannier molecule''. The sum of
the dipole moments of these ``molecules'' always gives the correct macroscopic
polarization, even under strong compression, when the overlap between nearby
Wannier functions becomes significant. We find that at megabar pressures the
contributions to the dipoles arising from the overlapping tails of the Wannier
functions is very large. The strong vibron infrared absorption experimentally
observed in phase III, above ~ 150 GPa, is analyzed in terms of the
vibron-induced fluctuations of the Wannier dipoles. We decompose these
fluctuations into ``static'' and ``dynamical'' contributions, and find that at
such high densities the latter term, which increases much more steeply with
pressure, is dominant.Comment: 17 pages, two-column style with 14 postscript figures embedded. Uses
REVTEX and epsf macro
Depth concentrations of deuterium ions implanted into some pure metals and alloys
Pure metals (Cu, Ti, Zr, V, Pd) and diluted Pd-alloys (Pd-Ag, Pd-Pt, Pd-Ru,
Pd-Rh) were implanted by 25 keV deuterium ions at fluences in the range
(1.2{\div}2.3)x1022 D+/m2. The post-treatment depth distributions of deuterium
ions were measured 10 days and three months after the implantation using
Elastic Recoil Detection Analysis (ERDA) and Rutherford Backscattering (RBS).
Comparison of the obtained results allowed to make conclusions about relative
stability of deuterium and hydrogen gases in pure metals and diluted Pd alloys.
Very high diffusion rates of implanted deuterium ions from V and Pd pure metals
and Pd alloys were observed. Small-angle X-ray scattering revealed formation of
nanosized defects in implanted corundum and titanium.Comment: 12 pages, 9 figure
Facilitation between invasive herbivores: hemlock woolly adelgid increases gypsy moth preference for and performance on eastern hemlock
Interactions between invertebrate herbivores with different feeding modes are common on longâlived woody plants. In cases where one herbivore facilitates the success of another, the consequences for their shared host plant may be severe. Eastern hemlock (Tsuga canadensis), a canopyâdominant conifer native to the eastern U.S., is currently threatened with extirpation by the invasive styletâfeeding hemlock woolly adelgid (Adelges tsugae). The effect of adelgid on invasive hemlockâfeeding folivores remains unknown. This study evaluated the impact of feeding by hemlock woolly adelgid on gypsy moth (Lymantria dispar) larval preference for, and performance on, eastern hemlock. To assess preference, 245 fieldâgrown hemlocks were surveyed for gypsy moth herbivory damage and laboratory pairedâchoice bioassays were conducted. To assess performance, gypsy moth larvae were reared to pupation on adelgidâinfested or uninfested hemlock foliage, and pupal weight, proportional weight gain, and larval period were analysed. Adelgidâinfested hemlocks experienced more gypsy moth herbivory than did uninfested control trees, and laboratory tests confirmed that gypsy moth larvae preferentially feed on adelgidâinfested hemlock foliage. Gypsy moth larvae reared to pupation on adelgidâinfested foliage gained more weight than larvae reared on uninfested control foliage. These results suggest that the synergistic effect of adelgid and gypsy moth poses an additional threat to eastern hemlock that may increase extirpation risk and ecological impact throughout most of its range
Bi12Rh3Cu2I5: A 3D Weak Topological Insulator with Monolayer Spacers and Independent Transport Channels
Topological insulators (TIs) are semiconductors with protected electronic surface states that allow dissipation-free transport. TIs are envisioned as ideal materials for spintronics and quantum computing. In Bi14Rh3I9, the first weak 3D TI, topology presumably arises from stacking of the intermetallic [(Bi4Rh)3I]2+ layers, which are predicted to be 2D TIs and to possess protected edge-states, separated by topologically trivial [Bi2I8]2â octahedra chains. In the new layered salt Bi12Rh3Cu2I5, the same intermetallic layers are separated by planar, i.e., only one atom thick, [Cu2I4]2â anions. Density functional theory (DFT)-based calculations show that the compound is a weak 3D TI, characterized by (Formula presented.), and that the topological gap is generated by strong spinâorbit coupling (E g,calc. ⌠10 meV). According to a bonding analysis, the copper cations prevent strong coupling between the TI layers. The calculated surface spectral function for a finite-slab geometry shows distinct characteristics for the two terminations of the main crystal faces âš001â©, viz., [(Bi4Rh)3I]2+ and [Cu2I4]2â. Photoelectron spectroscopy data confirm the calculated band structure. In situ four-point probe measurements indicate a highly anisotropic bulk semiconductor (E g,exp. = 28 meV) with path-independent metallic conductivity restricted to the surface as well as temperature-independent conductivity below 60 K
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