895 research outputs found

    Deriving the existence of BBˉB\bar{B}^* bound states from the X(3872) and Heavy Quark Symmetry

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    We discuss the possibility and the description of bound states between BB and Bˉ\bar{B}^* mesons. We argue that the existence of such a bound state can be deduced from (i) the weakly bound X(3872) state, (ii) certain assumptions about the short range dynamics of the DDˉD\bar{D}^* system and (iii) heavy quark symmetry. From these assumptions the binding energy of the possible BBˉB\bar{B}^* bound states is determined, first in a theory containing only contact interactions which serves as a straightforward illustration of the method, and then the effects of including the one pion exchange potential are discussed. In this latter case three isoscalar states are predicted: a positive and negative C-parity 3S13D1^3S_1-{}^3D_1 state with a binding energy of 20MeV20\,{\rm MeV} and 6MeV6\,{\rm MeV} below threshold respectively, and a positive C-parity 3P0^3P_0 shallow state located almost at the BBˉB\bar{B}^* threshold. However, large uncertainties are generated as a consequence of the 1/mQ1/m_Q corrections from heavy quark symmetry. Finally, the newly discovered isovector Zb(10610)Z_b(10610) state can be easily accommodated within the present framework by a minor modification of the short range dynamics.Comment: 21 pages, 3 figures; a sign error in the potential has been corrected and new predictions have been compute

    Recursive Detection and Analysis of Nanoparticles in Scanning Electron Microscopy Images

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    In this study, we present a computational framework tailored for the precise detection and comprehensive analysis of nanoparticles within scanning electron microscopy (SEM) images. The primary objective of this framework revolves around the accurate localization of nanoparticle coordinates, accompanied by secondary objectives encompassing the extraction of pertinent morphological attributes including area, orientation, brightness, and length. Constructed leveraging the robust image processing capabilities of Python, particularly harnessing libraries such as OpenCV, SciPy, and Scikit-Image, the framework employs an amalgamation of techniques, including thresholding, dilating, and eroding, to enhance the fidelity of image processing outcomes. The ensuing nanoparticle data is seamlessly integrated into the RStudio environment to facilitate meticulous post-processing analysis. This encompasses a comprehensive evaluation of model accuracy, discernment of feature distribution patterns, and the identification of intricate particle arrangements. The finalized framework exhibits high nanoparticle identification within the primary sample image and boasts 97\% accuracy in detecting particles across five distinct test images drawn from a SEM nanoparticle dataset. Furthermore, the framework demonstrates the capability to discern nanoparticles of faint intensity, eluding manual labeling within the control group.Comment: 9 pages, 10 figure

    Nuclear forces from chiral EFT: The unfinished business

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    In spite of the great progress we have seen in recent years in the derivation of nuclear forces from chiral effective field theory (EFT), some important issues are still unresolved. In this contribution, we discuss the open problems which have particular relevance for microscopic nuclear structure, namely, the proper renormalization of chiral nuclear potentials and sub-leading many-body forces.Comment: 16 pages, 3 figures; contribution to J. Phys. G, Special Issue, Focus Section: Open Problems in Nuclear Structur

    Biological control of Rhizoctonia solani in tomatoes with Trichoderma harzianum mutants

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    Biocontrol of Rhizoctonia solani in tomatoes cultivated under greenhouse and field conditions was analyzed using the Trichoderma harzianum mutants Th650-NG7, Th11A80.1, Th12A40.1, Th12C40.1 and Th12A10.1 and ThF2-1, respectively. Their innocuousness on tomato cultivars 92.95 and Gondola (greenhouse assays), and on cultivar Fortaleza (field assays) was established. Alginate pellets (1.7 g pellets/L soil) containing c.a1 x 105 colony forming units (cfu)/g pellet were applied to a soil previously inoculated with R. solani at transplant (greenhouse) or to a naturally infected soil (field). Controls considered parental wild strains, a chemical fungicide and no additions. Th11A 80.1, Th12A10.1 and Th650-NG7 prevented the 100% mortality of tomato plants cv. 92.95 caused by R. solani, and the 40% mortality in tomato plants cv. Gondola (greenhouse assays). Mortality reduction was reflected in canker level lessening and in plant parameters increases (development, fresh and dry weights). A different degree of susceptibility of tomato plants was observed, being Gondola cv. more resistant than 92.95 cv. to infection in a soil previously inoculated with R. solani. Tomato plants of cv. Fortaleza did not show mortality in naturally infected soils (field assays), where the mutant ThF2-1 reduced significantly the canker level caused by R. solani

    Chiral potentials, perturbation theory, and the 1S0 channel of NN scattering

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    We use nucleon-nucleon phase shifts obtained from experimental data, together with the chiral expansion for the long-distance part of the NN interaction, to obtain information about the short-distance piece of the NN potential that is at work in the 1S0 channel. We find that if the scale R that defines the separation between "long-" and "short-" distance is chosen to be \lsim 1.8 fm then the energy dependence produced by short-distance dynamics is well approximated by a two-term polynomial for Tlab < 200 MeV. We also find that a quantitative description of NN dynamics is possible, at least in this channel, if one treats the long-distance parts of the chiral NN potential in perturbation theory. However, in order to achieve this we have to choose a separation scale R that is larger than 1.0 fm.Comment: 19 pages, 4 figure

    The Inverse Amplitude Method in ππ\pi\pi Scattering in Chiral Perturbation Theory to Two Loops

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    The inverse amplitude method is used to unitarize the two loop ππ\pi\pi scattering amplitudes of SU(2) Chiral Perturbation Theory in the I=0,J=0I=0,J=0, I=1,J=1I=1,J=1 and I=2,J=0I=2,J=0 channels. An error analysis in terms of the low energy one-loop parameters lˉ1,2,3,4,\bar l_{1,2,3,4,} and existing experimental data is undertaken. A comparison to standard resonance saturation values for the two loop coefficients bˉ1,2,3,4,5,6\bar b_{1,2,3,4,5,6} is also carried out. Crossing violations are quantified and the convergence of the expansion is discussed.Comment: (Latex, epsfig) 30 pages, 13 figures, 8 table

    TRY plant trait database - enhanced coverage and open access

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    Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives

    Potential process 'hurdles' in the use of macroalgae as feedstock for biofuel production in the British Isles

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    This review examines the potential technical and energy balance hurdles in the production of seaweed biofuel, and particular for the MacroBioCrude processing pipeline for the sustainable manufacture of liquid hydrocarbon fuels from seaweed in the UK. The production of biofuel from seaweed is economically, energetically and technically challenging at scale. Any successful process appears to require both a method of preserving the seaweed for continuous feedstock availability and a method exploiting the entire biomass. Ensiling and gasification offer a potential solution to these two requirements. However there is need for more data particularly at a commercial scal

    Coarse graining ππ scattering

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    We carry out an analysis of ππ scattering in the I J = 00, 11 and 20 channels in configuration space up to a maximal center-of-mass energy √ s = 1.4 GeV. We separate the interaction into two regions marked by an elementarity radius of the system; namely, a long distance region above which pions can be assumed to interact as elementary particles and a short distance region where many physical effects cannot be disentangled. The long distance interaction is described by chiral dynamics, where a two-pionexchange potential is identified, computed and compared to lattice calculations. The short distance piece corresponds to a coarse grained description exemplified by a superposition of delta-shell potentials sampling the interaction with the minimal wavelength. We show how the so constructed nonperturbative scattering amplitude complies with the proper analytic structure, allowing for an explicit N/D type decomposition in terms of the corresponding Jost functions and fulfilling dispersion relations without subtractions. We also address renormalization issues in coordinate space and investigate the role of crossing when fitting the scattering amplitudes above and below threshold to Roy-equation results. At higher energies, we show how inelasticities can be described by one single complex and energy dependent parameter. A successful description of the data can be achieved with a minimal number of fitting parameters, suggesting that coarse graining is a viable approach to analyze hadronic processes.Work partially supported by Spanish MINEICO and European FEDER funds (grants FIS2014-59386-P, FIS2017-85053-C2-1-P and FPA2015- 64041-C2-1-P), Junta de Andalucía (grant FQM-225) and the Swiss National Science Foundation
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