895 research outputs found
Deriving the existence of bound states from the X(3872) and Heavy Quark Symmetry
We discuss the possibility and the description of bound states between
and 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 system and (iii) heavy quark
symmetry. From these assumptions the binding energy of the possible
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 state with a binding energy of and below threshold respectively, and a positive C-parity
shallow state located almost at the threshold. However,
large uncertainties are generated as a consequence of the corrections
from heavy quark symmetry. Finally, the newly discovered isovector
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
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
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
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
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 Scattering in Chiral Perturbation Theory to Two Loops
The inverse amplitude method is used to unitarize the two loop
scattering amplitudes of SU(2) Chiral Perturbation Theory in the ,
and channels. An error analysis in terms of the low energy
one-loop parameters and existing experimental data is
undertaken. A comparison to standard resonance saturation values for the two
loop coefficients 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
Metodología para la Determinación de la Capacidad de Carga de Visitantes, en las Áreas Marinas Protegidas de Cuba
TRY plant trait database - enhanced coverage and open access
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
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
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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