1,636 research outputs found
Advancing the time of ripeness of grapes by the application of methyl 2-(ureidooxy) propionate (a growth retardant)
Methyl 2-(ureidooxy) propionate (MUP), a plant growth retardant, hastened the ripening of grape berries of Vitis vinifera L. cultivars Mataro and Sultana by about 2 weeks and 1 week, respectively. The vines were sprayed with 0.1 % solution of MUP about halfway :through the first rapid growth phase of the fruit and again 2 weeks later. Terminal and lateral shoot growth was inhibited. Ripening of berries was advanced as measured by development of colour, and changes in titratable acid and reducing sugar content. The earlier ripening of the berries may have been due to hormonal changes but the advancement was much greater than that found previously with abscisic acid or ethylene applied during the slow growth stage of berry development.Die Beschleunigung des Reifezeitpunktes von Trauben durch die Anwendung vonMethyl-2-(ureidooxy)-Propionat, einen WachstumsdämpferMethyl-2-(ureidooxy)-Propionat (MUP), welches das Pflanzenwachstum verlangsamt, beschleunigte bei den Vitis-vinifera-Sorten Mataro und Sultana die Beerenreife um etwa 2 Wochen bzw. 1 Woche. Die Reben wurden etwa in der Mitte der ersten raschen Wachstumsphase der Beeren und ein weiteres Mal 2 Wochen später mit einer 0,1%igen MUP-Lösung besprüht. Das terminale und laterale Triebwachstum war gehemmt. Die Beerenreife war beschleunigt, wie die Entwicklung der Beerenfarbe und die Veränderungen im Gehalt an titrierbarer Säure und reduzierenden Zuckern zeigten. Die frühzeitigere Beerenreife könnte auf hormonale Veränderungen zurückgehen; allerdings war die Reife viel stärker beschleunigt als im Fall früherer Versuche, in denen während der langen Wachstumsphase der Beerenentwicklung Abscisinsäure oder Äthylen angewandt worden waren
Gluon distributions in nucleons and pions at a low resolution scale
In this paper we study the gluon distribution functions in nucleons and pions
at a low resolution scale. This is an important issue since parton
densities at low have always been taken as an external input which is
adjusted through DGLAP evolution to fit the experimental data at higher scales.
Here, in the framework of a model recently developed, it is shown that the
hypothetical cloud of {\it neutral} pions surrounding nucleons and pions
appears to be responsible for the characteristic valence-like gluon
distributions needed at the inital low scale. As an additional result, we get
the remarkable prediction that neutral and charged pions have different
intrinsic sea flavor contents.Comment: final version to appear in Phys. Rev. D. Discussion on several points
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Targeting building energy efficiency using thermal infrared earth observation telescopes
Abstract
Upgrading the energy performance of the UK’s entire building stock is the central pillar of any credible and cost-effective strategy to meeting net zero. This research aims to open up the revenue of using thermal infrared data from satellites to assist in processes on building energy performance improvement. High-resolution thermal infrared data output from space offers the potential for fast and effective monitoring provision that can cover large areas and targeted buildings or sites. We have interviewed a set of stakeholders from government, industry and community groups to build the specific use cases and find out detailed user requirements.</jats:p
Next-to-Leading Order Constituent Quark Structure and Hadronic Structure Functions
We calculate the partonic structure of a constituent quark in the
Next-to-Leading Order framework. The structure of any hadron can be obtained
thereafter using a convolution method. Such a procedure is used to generate the
structure function of proton and pion in NLO, neglecting certain corrections to
. It is shown that while the constituent quark structure is
generated purely perturbatively and accounts for the most part of the hadronic
structure, there is a few percent contributions coming from the nonperturbative
sector in the hadronic structure. This contribution plays the key role in
explaining the SU(2) symmetry breaking of the nucleon sea and the observed
violation of Gottfried sum rule. These effects are calculated. We obtained an
Excellent agreement with the experimental data in a wide range of and for the proton structure function. We
have also calculated Pion structure and compared it with the existing data.
Again, the model calculations agree rather well with the data from experiment.Comment: 32 pages,10 figures, Accepted to publish in Phys. Rev.
Testing the Meson Cloud Model in Inclusive Meson Production
We have applied the Meson Cloud Model to calculate inclusive momentum spectra
of pions and kaons produced in high energy proton-proton and proton-nucleus
collisions. For the first time these data are used to constrain the cloud
cut-off parameters. We show that it is possible to obtain a reasonable
description of data, especially the large () part of the
spectrum and at the same time describe (partially) the E866 data on and . We also discuss the relative strength of the
and vertices. We find out that the corresponding cut-off
parameters should be both soft and should not differ by more than 200 MeV from
each other. An additional source (other than the meson cloud) of sea antiquark
asymmetry, seems to be necessary to completely explain the data. A first
extension of the MCM to proton nucleus collisions is discussed.Comment: 14 pages, Latex, 6 ps figures. Submitted to Phys. Rev.
Flavor and Charge Symmetry in the Parton Distributions of the Nucleon
Recent calculations of charge symmetry violation(CSV) in the valence quark
distributions of the nucleon have revealed that the dominant symmetry breaking
contribution comes from the mass associated with the spectator quark
system.Assuming that the change in the spectator mass can be treated
perturbatively, we derive a model independent expression for the shift in the
parton distributions of the nucleon. This result is used to derive a relation
between the charge and flavor asymmetric contributions to the valence quark
distributions in the proton, and to calculate CSV contributions to the nucleon
sea. The CSV contribution to the Gottfried sum rule is also estimated, and
found to be small
Parton model versus color dipole formulation of the Drell-Yan process
In the kinematical region where the center of mass energy is much larger than
all other scales, the Drell-Yan process can be formulated in the target rest
frame in terms of the same color dipole cross section as low Bjorken-x deep
inelastic scattering. Since the mechanisms for heavy dilepton production appear
very different in the dipole approach and in the conventional parton model, one
may wonder whether these two formulations really represent the same physics. We
perform a comparison of numerical calculations in the color dipole approach
with calculations in the next-to-leading order parton model. For proton-proton
scattering, the results are very similar at low x_2 from fixed target to RHIC
energies, confirming the close connection between these two very different
approaches. We also compare the transverse momentum distributions of Drell-Yan
dileptons predicted in both formulations. The range of applicability of the
dipole formulation and the impact of future Drell-Yan data from RHIC for
determining the color dipole cross section are discussed. A detailed derivation
of the dipole formulation of the Drell-Yan process is also included.Comment: 20 pages, 5 figure
Parton energy loss limits and shadowing in Drell-Yan dimuon production
A precise measurement of the ratios of the Drell-Yan cross section per
nucleon for an 800 GeV/c proton beam incident on Be, Fe and W targets is
reported. The behavior of the Drell-Yan ratios at small target parton momentum
fraction is well described by an existing fit to the shadowing observed in
deep-inelastic scattering. The cross section ratios as a function of the
incident parton momentum fraction set tight limits on the energy loss of quarks
passing through a cold nucleus
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