1,313 research outputs found

    The Influence of Intensity of Tree Thinning on the Redistribution of Soil Water in Southern African Mopani Veld

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    The investigation was conducted on a densely wooded area in the Mopani veld of South Africa. Six plots were subjected to different intensities of tree thinning, ranging from a totally cleared plot (0 %) to plots thinned to the equivalent of 10%, 20%, 35%, 50% and 75% of the leaf biomass of a control plot (100%). Soil water measurements were taken at six different depths to a depth of 825 mm. The infiltration of rain water and redistribution within the soil profile exhibited marked differences between experimental plots. The soil water was predominantly held at a very shallow depth (\u3c450 mm). Increased infiltration in plots with a low tree density occurred and was associated with the establishment of grasses. No stratification of soil water between the topsoil and subsoil could be established which means that the C. mopane trees and grasses are in direct competition for soil water in the upper soil layers

    SU(3) Decomposition of Two-Body B Decay Amplitudes

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    We present the complete flavor SU(3) decomposition of decay amplitudes for decays of the triplet (B^+_u, B^0_d, B^0_s) of B mesons nonleptonically into two pseudoscalar mesons. This analysis holds for arbitrarily broken SU(3) and can be used to generate amplitude relations when physical arguments permit one to neglect or relate any of the reduced amplitudes.Comment: 31 pages, revtex, no figure

    Monitoring of the medication distribution and the refrigeration temperature in a pharmacy based on internet of things (IoT) technology

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    Abstract: For the past 15 years since its appearance, Internet of Things (IoT) technology has been leading the planet towards a smart world where all devices and physical objects, referred to as “things”, will be connected via electronic sensors through the Internet. The distribution of medication to patients at a pharmacy in certain regions is still very traditional and outdated. Patients wait for a long time in queues to receive their medications, this is mostly due to the absence of an efficient distribution system. Also, the refrigeration temperature within several pharmacies is a huge problem, as medications must be kept at a constant temperature for an optimal results..

    Chiral effective theory predictions for deuteron form factor ratios at low Q^2

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    We use chiral effective theory to predict the deuteron form factor ratio G_C/G_Q as well as ratios of deuteron to nucleon form factors. These ratios are calculated to next-to-next-to-leading order. At this order the chiral expansion for the NN isoscalar charge operator (including consistently calculated 1/M corrections) is a parameter-free prediction of the effective theory. Use of this operator in conjunction with NLO and NNLO chiral effective theory wave functions produces results that are consistent with extant experimental data for Q^2 < 0.35 GeV^2. These wave functions predict a deuteron quadrupole moment G_Q(Q^2=0)=0.278-0.282 fm^2-with the variation arising from short-distance contributions to this quantity. The variation is of the same size as the discrepancy between the theoretical result and the experimental value. This motivates the renormalization of G_Q via a two-nucleon operator that couples to quadrupole photons. After that renormalization we obtain a robust prediction for the shape of G_C/G_Q at Q^2 < 0.3 GeV^2. This allows us to make precise, model-independent predictions for the values of this ratio that will be measured at the lower end of the kinematic range explored at BLAST. We also present results for the ratio G_C/G_M.Comment: 31 pages, 7 figure

    The Lambda-Lambda Interaction and ^{6}_{Lambda Lambda}He

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    An OBE potential model for the ^{1}S_0 S = -2 interaction is analyzed with emphasis on the role of coupling between the Lambda Lambda, N Xi, and Sigma Sigma channels. Singlet scalar exchange, an approximation to two-pion exchange, is significant in all channels; surprisingly, the one-pion exchange component is almost negligible. The size of the channel coupling as a function of the overall strength of the OBE model potential is examined. Implications of the analysis for the binding energy of ^{6}_{Lambda Lambda}He are considered; the new experimental datum may suggest a consistency between the extracted Lambda Lambda matrix element and the relation implied by SU(3) among OBE baryon-baryon interactions. \\Comment: 4 pages brief report to Physical Review

    Bounds on the Complexity of Halfspace Intersections when the Bounded Faces have Small Dimension

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    We study the combinatorial complexity of D-dimensional polyhedra defined as the intersection of n halfspaces, with the property that the highest dimension of any bounded face is much smaller than D. We show that, if d is the maximum dimension of a bounded face, then the number of vertices of the polyhedron is O(n^d) and the total number of bounded faces of the polyhedron is O(n^d^2). For inputs in general position the number of bounded faces is O(n^d). For any fixed d, we show how to compute the set of all vertices, how to determine the maximum dimension of a bounded face of the polyhedron, and how to compute the set of bounded faces in polynomial time, by solving a polynomial number of linear programs

    Nucleon-nucleon interaction in the JJ-matrix inverse scattering approach and few-nucleon systems

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    The nucleon-nucleon interaction is constructed by means of the JJ-matrix version of inverse scattering theory. Ambiguities of the interaction are eliminated by postulating tridiagonal and quasi-tridiagonal forms of the potential matrix in the oscillator basis in uncoupled and coupled waves, respectively. The obtained interaction is very accurate in reproducing the NNNN scattering data and deuteron properties. The interaction is used in the no-core shell model calculations of 3^3H and 4^4He nuclei. The resulting binding energies of 3^3H and 4^4He are very close to experimental values.Comment: Text is revised, new figures and references adde

    Soft-core hyperon-nucleon potentials

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    A new Nijmegen soft-core OBE potential model is presented for the low-energy YN interactions. Besides the results for the fit to the scattering data, which largely defines the model, we also present some applications to hypernuclear systems using the G-matrix method. An important innovation with respect to the original soft-core potential is the assignment of the cut-off masses for the baryon-baryon-meson (BBM) vertices in accordance with broken SU(3)F_F, which serves to connect the NN and the YN channels. As a novel feature, we allow for medium strong breaking of the coupling constants, using the 3P0^3P_0 model with a Gell-Mann--Okubo hypercharge breaking for the BBM coupling. We present six hyperon-nucleon potentials which describe the available YN cross section data equally well, but which exhibit some differences on a more detailed level. The differences are constructed such that the models encompass a range of scattering lengths in the ΣN\Sigma N and ΛN\Lambda N channels. For the scalar-meson mixing angle we obtained values θS=37\theta_S=37 to 40 degrees, which points to almost ideal mixing angles for the scalar qqˉq\bar{q} states. The G-matrix results indicate that the remarkably different spin-spin terms of the six potentials appear specifically in the energy spectra of Λ\Lambda hypernuclei.Comment: 37 pages, 4 figure

    Heavy Quark Solitons: Strangeness and Symmetry Breaking

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    We discuss the generalization of the Callan-Klebanov model to the case of heavy quark baryons. The light flavor group is considered to be SU(3)SU(3) and the limit of heavy spin symmetry is taken. The presence of the Wess-Zumino-Witten term permits the neat development of a picture , at the collective level, of a light diquark bound to a ``heavy" quark with decoupled spin degree of freedom. The consequences of SU(3)SU(3) symmetry breaking are discussed in detail. We point out that the SU(3)SU(3) mass splittings of the heavy baryons essentially measure the ``low energy" physics once more and that the comparison with experiment is satisfactory.Comment: 17 pages, RevTEX. Minor typos corrected and new references adde

    Semiclassical quantization of SU(3) skyrmions

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    Semiclassical quantization of the SU(3)-skyrmions is performed by means of the collective coordinate method. The quantization condition known for the SU(2)-solitons quantized with SU(3) collective coordinates is generalized for the SU(3) skyrmions with strangeness content different from zero. Quantization of the dipole-type configuration with large strangeness content found recently is considered as an example, the spectrum and the mass splitting of the quantized states are estimated. The energy and baryon number density of SU(3) skyrmions are presented in the form emphasizing their symmetry in different SU(2) subgroups of SU(3), and the lower boundary for the static energy of SU(3) skyrmions is derived.Comment: 16 pages, 2 figures (available upon request). Submitted to JETP on May 6, 1997; in print. A preliminary short version of this paper is hep-th/960916
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