7,646 research outputs found

    Species Delimitation among Southeastern US Oxyloma (Gastropoda: Succineidae)

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    The Succineid genus Oxyloma found throughout Canada and United States contains approximately 15 described species whose criterion for differentiation is considered unreliable. As a first step towards understanding the evolutionary history and revising the taxonomy of North American Oxyloma, we have sampled four species found in eastern North America (O. salleana, O. subeffusa, O. effusa, and O. retusa) from their type localities. We used mitochondrial COI, and nuclear LSU sequences with samples found across their range and members of the family to produce a phylogenetic hypothesis of evolutionary relationships and test species boundaries. Molecular phylogeny and species delimitation analyses using mitochondrial and nuclear data finds three monophyletic groups among the four nominal Oxyloma species, confirming doubts concerning the validity of these species

    Two complete mitochondrial genomes from Praticolella mexicana Perez, 2011 (Polygyridae) and gene order evolution in Helicoidea (Mollusca, Gastropoda)

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    Helicoidea is a diverse group of land snails with a global distribution. While much is known regarding the relationships of helicoid taxa, comparatively little is known about the evolution of the mitochondrial genome in the superfamily. We sequenced two complete mitochondrial genomes from Praticolella mexicana Perez, 2011 representing the first such data from the helicoid family Polygyridae, and used them in an evolutionary analysis of mitogenomic gene order. We found the mitochondrial genome of P. mexicana to be 14,008 bp in size, possessing the typical 37 metazoan genes. Multiple alternate stop codons are used, as are incomplete stop codons. Mitogenome size and nucleotide content is consistent with other helicoid species. Our analysis of gene order suggested that Helicoidea has undergone four mitochondrial rearrangements in the past. Two rearrangements were limited to tRNA genes only, and two involved protein coding gene

    Two Complete Mitochondrial Genomes from \u3cem\u3ePraticolella mexicana\u3c/em\u3e Perez, 2011 (Polygyridae) and Gene Order Evolution in Helicoidea (Mollusca, Gastropoda)

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    Helicoidea is a diverse group of land snails with a global distribution. While much is known regarding the relationships of helicoid taxa, comparatively little is known about the evolution of the mitochondrial genome in the superfamily. We sequenced two complete mitochondrial genomes from Praticolella mexicana Perez, 2011 representing the first such data from the helicoid family Polygyridae, and used them in an evolutionary analysis of mitogenomic gene order. We found the mitochondrial genome of P. mexicana to be 14,008 bp in size, possessing the typical 37 metazoan genes. Multiple alternate stop codons are used, as are incomplete stop codons. Mitogenome size and nucleotide content is consistent with other helicoid species. Our analysis of gene order suggested that Helicoidea has undergone four mitochondrial rearrangements in the past. Two rearrangements were limited to tRNA genes only, and two involved protein coding genes

    Two complete mitochondrial genomes from Praticolella mexicana Perez, 2011 (Polygyridae) and gene order evolution in Helicoidea (Mollusca, Gastropoda)

    Get PDF
    Helicoidea is a diverse group of land snails with a global distribution. While much is known regarding the relationships of helicoid taxa, comparatively little is known about the evolution of the mitochondrial genome in the superfamily. We sequenced two complete mitochondrial genomes from Praticolella mexicana Perez, 2011 representing the first such data from the helicoid family Polygyridae, and used them in an evolutionary analysis of mitogenomic gene order. We found the mitochondrial genome of P. mexicana to be 14,008 bp in size, possessing the typical 37 metazoan genes. Multiple alternate stop codons are used, as are incomplete stop codons. Mitogenome size and nucleotide content is consistent with other helicoid species. Our analysis of gene order suggested that Helicoidea has undergone four mitochondrial rearrangements in the past. Two rearrangements were limited to tRNA genes only, and two involved protein coding gene

    Stated benefits from urban afforestation in an arid city: a contingent valuation in Mexicali, Baja California, Mexico

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    The pervasiveness of particulate matter in arid cities has yet to be discussed and tackled. Given that urban trees have been documented to provide air-filtering and dry deposition services, this study documents the stated benefits from an urban afforestation scenario in Mexicali –an arid city located northwest Mexico at the US-Mexico border. Our doublebounded dichotomous contingent valuation protocol yields an estimated average annual willingness to pay (WTP) of USD 88 per household. Variations in the WTP are associated with perception of air quality and presence of respiratory symptoms in the respondent’s household. The smallest WTP (USD 75) is reported by respondents perceiving poor air quality in their neighborhood and with no household members affected by respiratory symptoms. In contrast, respondents perceiving good air quality and with at least one household member facing respiratory symptoms reported a WTP of USD 99. The average stated benefits represent around 0.8% of the annual household income

    Stated benefits from air quality improvement through urban afforestation in an arid city – A contingent valuation in Mexicali, Baja California, Mexico

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    Cities in drylands are expected to experience increasing challenges when it comes to air pollution. Currently, concentrations of particulate matter in these cities frequently reach dangerous levels. Urban afforestation represents an alternative to increase human health in arid cities via air-filtering and dry deposition. By simulating a non-existing market through a contingent valuation protocol, this study estimates the willingness to contribute monetarily to an urban afforestation scenario in Mexicali -an arid city located at the US-Mexico border. We estimate an average annual willingness to pay (WTP) of (2019) USD 88 per household. Variations in WTP are associated with the respondent's perception of air quality and the presence of respiratory symptoms in the respondent's household. The smallest WTP (USD 75) is reported by those perceiving poor air quality in their neighborhood and with no household members affected by respiratory symptoms. Respondents perceiving good air quality and with at least one household member facing respiratory symptoms report a WTP of USD 99. The highest WTP represents around 0.8 % of the annual household income. This WTP, when extrapolated to and aggregated over the total number of households in Mexicali, justifies the implementation of an urban afforestation program supplying 30 thousand tree seedlings annually

    Geometrodynamical Formulation of Two-Dimensional Dilaton Gravity

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    Two-dimensional matterless dilaton gravity with arbitrary dilatonic potential can be discussed in a unitary way, both in the Lagrangian and canonical frameworks, by introducing suitable field redefinitions. The new fields are directly related to the original spacetime geometry and in the canonical picture they generalize the well-known geometrodynamical variables used in the discussion of the Schwarzschild black hole. So the model can be quantized using the techniques developed for the latter case. The resulting quantum theory exhibits the Birkhoff theorem at the quantum level.Comment: 15 pages, LATE

    Search for the rare decays B0→J/ÏˆÎłB^{0}\to J/\psi \gamma and Bs0→J/ÏˆÎłB^{0}_{s} \to J/\psi \gamma

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    A search for the rare decay of a B0B^{0} or Bs0B^{0}_{s} meson into the final state J/ÏˆÎłJ/\psi\gamma is performed, using data collected by the LHCb experiment in pppp collisions at s=7\sqrt{s}=7 and 88 TeV, corresponding to an integrated luminosity of 3 fb−1^{-1}. The observed number of signal candidates is consistent with a background-only hypothesis. Branching fraction values larger than 1.7×10−61.7\times 10^{-6} for the B0→J/ÏˆÎłB^{0}\to J/\psi\gamma decay mode are excluded at 90% confidence level. For the Bs0→J/ÏˆÎłB^{0}_{s}\to J/\psi\gamma decay mode, branching fraction values larger than 7.4×10−67.4\times 10^{-6} are excluded at 90% confidence level, this is the first branching fraction limit for this decay.Comment: All figures and tables, along with any supplementary material and additional information, are available at https://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2015-044.htm

    Multi-particle azimuthal correlations in p-Pb and Pb-Pb collisions at the CERN Large Hadron Collider

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    Measurements of multi-particle azimuthal correlations (cumulants) for charged particles in p-Pb and Pb-Pb collisions are presented. They help address the question of whether there is evidence for global, flow-like, azimuthal correlations in the p-Pb system. Comparisons are made to measurements from the larger Pb-Pb system, where such evidence is established. In particular, the second harmonic two-particle cumulants are found to decrease with multiplicity, characteristic of a dominance of few-particle correlations in p-Pb collisions. However, when a âˆŁÎ”Î·âˆŁ|\Delta \eta| gap is placed to suppress such correlations, the two-particle cumulants begin to rise at high-multiplicity, indicating the presence of global azimuthal correlations. The Pb-Pb values are higher than the p-Pb values at similar multiplicities. In both systems, the second harmonic four-particle cumulants exhibit a transition from positive to negative values when the multiplicity increases. The negative values allow for a measurement of v2{4}v_{2}\{4\} to be made, which is found to be higher in Pb-Pb collisions at similar multiplicities. The second harmonic six-particle cumulants are also found to be higher in Pb-Pb collisions. In Pb-Pb collisions, we generally find v2{4}≃v2{6}≠0v_{2}\{4\} \simeq v_{2}\{6\}\neq 0 which is indicative of a Bessel-Gaussian function for the v2v_{2} distribution. For very high-multiplicity Pb-Pb collisions, we observe that the four- and six-particle cumulants become consistent with 0. Finally, third harmonic two-particle cumulants in p-Pb and Pb-Pb are measured. These are found to be similar for overlapping multiplicities, when a âˆŁÎ”Î·âˆŁ>1.4|\Delta\eta| > 1.4 gap is placed.Comment: 25 pages, 11 captioned figures, 3 tables, authors from page 20, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/87

    Multiplicity dependence of jet-like two-particle correlations in p-Pb collisions at sNN\sqrt{s_{NN}} = 5.02 TeV

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    Two-particle angular correlations between unidentified charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV. The transverse-momentum range 0.7 <pT,assoc<pT,trig< < p_{\rm{T}, assoc} < p_{\rm{T}, trig} < 5.0 GeV/cc is examined, to include correlations induced by jets originating from low momen\-tum-transfer scatterings (minijets). The correlations expressed as associated yield per trigger particle are obtained in the pseudorapidity range ∣η∣<0.9|\eta|<0.9. The near-side long-range pseudorapidity correlations observed in high-multiplicity p-Pb collisions are subtracted from both near-side short-range and away-side correlations in order to remove the non-jet-like components. The yields in the jet-like peaks are found to be invariant with event multiplicity with the exception of events with low multiplicity. This invariance is consistent with the particles being produced via the incoherent fragmentation of multiple parton--parton scatterings, while the yield related to the previously observed ridge structures is not jet-related. The number of uncorrelated sources of particle production is found to increase linearly with multiplicity, suggesting no saturation of the number of multi-parton interactions even in the highest multiplicity p-Pb collisions. Further, the number scales in the intermediate multiplicity region with the number of binary nucleon-nucleon collisions estimated with a Glauber Monte-Carlo simulation.Comment: 23 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/161
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