4,148 research outputs found

    Notes on a new mealybug (Hemiptera: Coccoidea: Pseudococcidae) pest in Florida and the Caribbean : the papaya mealybug, Paracoccus marginatus Williams and Granara de Willink

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    Paracoccus marginatus Williams and Granara de Willink, here called the papaya mealybug, was first detected in the United States in Hollywood, Florida in 1998. By the end of 1998 it was found in four localities in the state and has since spread to nine localities in five counties. This mealybug appears to have moved through the Caribbean area since its 1994 detection in the Dominican Republic. The pest is reported to cause serious damage to tropical fruit, especially papaya, and has been detected most frequently, in Florida, on hibiscus. It is now known from Antigua, Belize, the British Virgin Islands, Costa Rica, Guatemala, Mexico, Nevis, Puerto Rico, St. Barthelemy, St. Kitts, St. Martin, and the US Virgin Islands. Hosts include: Acacia sp.(Luguminosae), Acalypha sp.(Euphorbiaceae), Ambrosia cumanensis (Compositae), Annona squamosa (Annonaceae), Carica papaya (Caricaceae), Guazuma ulmifolia (Sterculiaccea), Hibiscus rosa-sinensis (Euphorbiaceae), Hibiscus sp. (Euphorbiaceae), Ipomoea sp. (Convolvulaceae), Manihot chloristica (Euphorbiaceae), Manihot esculenta (Euphorbiaceae), Mimosa pigra (Lugiminosae), Parthenium hysterophorus (Compositae), Persea americana (Lauraceae), Plumeria sp. (Apocynaceae), Sida sp. (Malvaceae), Solanum melongena (Solanaceae). The species is believed to be native to Mexico andlor Central America

    Root exudates of the hyperaccumulator Thlaspi caerulescens do not enhance metal mobilization

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    To examine whether root exudates of the Zn/Cd hyperaccumulator Thlaspi caerulescens play a role in metal hyperaccumulation, we compared the metal mobilization capacity of root exudates collected from two ecotypes of T. caerulescens, and from the nonaccumulators wheat (Triticum aestivum) and canola (Brassica napus). Plants were grown hydroponically and three treatments (control, -Fe and -Zn) were later imposed for 2 wk before collection of root exudates. On a basis of root d. wt, the total soluble organic C in the root exudates of T. caerulescens was similar to that of wheat, and significantly higher than that of canola. In all treatment, the root exudates of T. caerulescens and canola mobilized little Cu and Zn from Cu- or Zn-loaded resins, and little Zn, Cd, Cu or Fe from a contaminated calcareous soil. By contrast, the root exudates of wheat generally mobilized more metals from both resin and soil. In particular, the -Fe treatment, and to a lesser extent the -Zn treatment, elicited large increases in the metal mobilization capacity of the root exudates from wheat. We conclude that root exudates from T. caerulescens do not significantly enhance mobilization of Zn and Cd, and therefore are not involved in Zn and Cd hyperaccumulation. (C) New Phytologist (2001)

    Spatial and temporal distribution patterns of Anopheles arabiensis breeding sites in La Reunion Island - multi-year trend analysis of historical records from 1996-2009

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    <p>Abstract</p> <p>Background</p> <p>An often confounding facet of the dynamics of malaria vectors is the aquatic larval habitat availability and suitable conditions under which they can thrive. Here, we investigated the impact of environmental factors on the temporal and spatial distribution of larval habitats of <it>Anopheles </it><it>arabiensis </it>in different locations on La Reunion Island.</p> <p>Methods</p> <p>A retrospective examination was made from archival data which provided the complete enumeration of <it>An. arabiensis </it>breeding habitats in three distinct geographic zones - extending North-east, West and South of the island over 14 years, from January 1996 to December 2009. Data on the occurrence and the number of active larval habitats at each of a total of 4376 adjacent ellipsoid grid cells (216,506 square meters each) were used (1) to provide the geographic extent of breeding site availability from year to year and (2) to analyze associations with prevailing environmental factors, habitat types, and locations.</p> <p>Results</p> <p><it>Anopheles arabiensis </it>utilized a spectrum of man-made and natural aquatic habitats, most of which were concentrated primarily in the rock pools located in ravines and river fringes, and also in the large littoral marshes and within the irrigated agricultural zones. The numbers of breeding site per sampling grid differed significantly in different parts of the island. In contrast to an originally more widespread distribution across the island in the 1950s, detailed geographic analyses of the data obtained in the period extending from 1996-2009 showed an intriguing clustered distribution of active breeding sites in three discontinuous geographic zones, in which aquatic habitats availability fluctuates with the season and year. Seasonality in the prevalence of anopheles breeding sites suggests significant responsiveness to climatic factors.</p> <p>Conclusions</p> <p>The observed retreat of <it>An. arabiensis </it>distribution range to lower altitudinal zones (< 400 m) and the upward shift in the most remote littoral areas in the northeast and southwest regions suggest the possible influence of biogeographic factors, changes in land use and control operations. The results of this study would allow for a more rational implementation of control strategies across the island.</p

    Observation of time-reversal violation in the B0 meson system

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    The individually named authors work collectively as The BABAR Collaboration. Copyright @ 2012 American Physical Society.Although CP violation in the B meson system has been well established by the B factories, there has been no direct observation of time-reversal violation. The decays of entangled neutral B mesons into definite flavor states (B0 or B¯¯¯0), and J/ψK0L or cc¯K0S final states (referred to as B+ or B−), allow comparisons between the probabilities of four pairs of T-conjugated transitions, for example, B¯¯¯0→B− and B−→B¯¯¯0, as a function of the time difference between the two B decays. Using 468×106 BB¯¯¯ pairs produced in Υ(4S) decays collected by the BABAR detector at SLAC, we measure T-violating parameters in the time evolution of neutral B mesons, yielding ΔS+T=−1.37±0.14(stat)±0.06(syst) and ΔS−T=1.17±0.18(stat)±0.11(syst). These nonzero results represent the first direct observation of T violation through the exchange of initial and final states in transitions that can only be connected by a T-symmetry transformation.DOE and NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3 (France), BMBF and DFG(Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MES (Russia), MINECO (Spain), STFC (United Kingdom). Individuals have received support from the Marie Curie EIF (European Union), the A. P. Sloan Foundation (USA) and the Binational Science Foundation (USA-Israel)

    Branching fraction and form-factor shape measurements of exclusive charmless semileptonic B decays, and determination of |V_{ub}|

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    We report the results of a study of the exclusive charmless semileptonic decays, B^0 --> pi^- l^+ nu, B^+ --> pi^0 l^+ nu, B^+ --> omega l^+ nu, B^+ --> eta l^+ nu and B^+ --> eta^' l^+ nu, (l = e or mu) undertaken with approximately 462x10^6 B\bar{B} pairs collected at the Upsilon(4S) resonance with the BABAR detector. The analysis uses events in which the signal B decays are reconstructed with a loose neutrino reconstruction technique. We obtain partial branching fractions in several bins of q^2, the square of the momentum transferred to the lepton-neutrino pair, for B^0 --> pi^- l^+ nu, B^+ --> pi^0 l^+ nu, B^+ --> omega l^+ nu and B^+ --> eta l^+ nu. From these distributions, we extract the form-factor shapes f_+(q^2) and the total branching fractions BF(B^0 --> pi^- l^+ nu) = (1.45 +/- 0.04_{stat} +/- 0.06_{syst})x10^-4 (combined pi^- and pi^0 decay channels assuming isospin symmetry), BF(B^+ --> omega l^+ nu) = (1.19 +/- 0.16_{stat} +/- 0.09_{syst})x10^-4 and BF(B^+ --> eta l^+ nu) = (0.38 +/- 0.05_{stat} +/- 0.05_{syst})x10^-4. We also measure BF(B^+ --> eta^' l^+ nu) = (0.24 +/- 0.08_{stat} +/- 0.03_{syst})x10^-4. We obtain values for the magnitude of the CKM matrix element V_{ub} by direct comparison with three different QCD calculations in restricted q^2 ranges of B --> pi l^+ nu decays. From a simultaneous fit to the experimental data over the full q^2 range and the FNAL/MILC lattice QCD predictions, we obtain |V_{ub}| = (3.25 +/- 0.31)x10^-3, where the error is the combined experimental and theoretical uncertainty.Comment: 35 pages, 14 figures, submitted to PR

    Search for lepton-number violating processes in B+ -> h- l+ l+ decays

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    We have searched for the lepton-number violating processes B+ -> h- l+ l+ with h- = K-/pi- and l+ = e+/mu+, using a sample of 471+/-3 million BBbar events collected with the BaBar detector at the PEP-II e+e- collider at the SLAC National Accelerator Laboratory. We find no evidence for these decays and place 90% confidence level upper limits on their branching fractions Br(B+ -> pi- e+ e+) K- e+ e+) pi- mu+ mu+) K- mu+ mu+) < 6.7 x 10^{-8}.Comment: 8 pages, 4 postscript figures, submitted to Phys. Rev. D. R
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