1,042 research outputs found
Nuclear Force from Lattice QCD
The first lattice QCD result on the nuclear force (the NN potential) is
presented in the quenched level. The standard Wilson gauge action and the
standard Wilson quark action are employed on the lattice of the size 16^3\times
24 with the gauge coupling beta=5.7 and the hopping parameter kappa=0.1665. To
obtain the NN potential, we adopt a method recently proposed by CP-PACS
collaboration to study the pi pi scattering phase shift. It turns out that this
method provides the NN potentials which are faithful to those obtained in the
analysis of NN scattering data. By identifying the equal-time Bethe-Salpeter
wave function with the Schroedinger wave function for the two nucleon system,
the NN potential is reconstructed so that the wave function satisfies the
time-independent Schroedinger equation. In this report, we restrict ourselves
to the J^P=0^+ and I=1 channel, which enables us to pick up unambiguously the
``central'' NN potential V_{central}(r). The resulting potential is seen to
posses a clear repulsive core of about 500 MeV at short distance (r < 0.5 fm).
Although the attraction in the intermediate and long distance regions is still
missing in the present lattice set-up, our method is appeared to be quite
promising in reconstructing the NN potential with lattice QCD.Comment: A talk given at the XXIV International Symposium on Lattice Field
Theory (Lattice2006), Tucson, Arizona, USA, July 23-28, 2006, 3 figures,
7page
Recent advances in the theory of nuclear forces
After a brief historical review, we present recent progress in our
understanding of nuclear forces in terms of chiral effective field theory.Comment: 6 pages, 2 figures; talk at International Symposium on Correlations
Dynamics in Nuclei, University of Tokyo, Japan, 31 January-4 February, 200
Effects from inhomogeneities in the chiral transition
We consider an approximation procedure to evaluate the finite-temperature
one-loop fermionic density in the presence of a chiral background field which
systematically incorporates effects from inhomogeneities in the chiral field
through a derivative expansion. We apply the method to the case of a simple
low-energy effective chiral model which is commonly used in the study of the
chiral phase transition, the linear sigma-model coupled to quarks. The
modifications in the effective potential and their consequences for the bubble
nucleation process are discussed.Comment: 11 pages, 5 figures. v2: appendix and references added, published
versio
Rhizosphere microbial community manipulation under salted soil by the inoculation of Pseudomonas sp CMAA 1215 in Zea mays.
Soil salinity reduces the soil organic carbon stock, the microbial biomass and activity and modifies the biogeochemical cycle and the microbial diversity. Osmotic stress caused by ethylene on plants can be reduced using 1-aminocyclopropane-1-carboxylate (ACC) deaminase plant growth promoting bacteria (PGPR) producers. Studies of PGPR and commercially strains are based only on the growth of the plant without concern about modification of the microbial community. This scenario has shown an increasing need to study the ecological functions of bacterial community on salted soil and to develop new technologies to reduce environmental impacts and waste of natural resources. Our aim was to study the influence of the Pseudomonas sp. CMAA1215, a known ACC deaminase on rhizosphere bacteria community of Zea mays under saline soil by sequencing the rhizosphere metagenome. The NMDS of the OTU table (ANOSIM p<0.01) discriminate all the treatments (with and without inoculation under salted and non-salted soils) indicating a modification of the bacteria community by inoculation or by soil salinization. The main groups of the rhizosphere that had the abundance increased by Pseudomonas inoculation were Acidobacteriales, Solibacteriales, Bacillales and Rhizobiales. The relative abundance of Rhodospirillales (Alphaproteobacteria) and Chthoniobacterales (Spartobacteria) was stimulated by the inoculation only under higher salinization. The inoculation can be important to stimulate other PGPR under saline soil or microbes that are not benefic to plants
Scalar Glueball Decay Into Pions In Effective Theory
We discuss the mixing between the sigma meson sigma and the "pure" glueball
field H and study the decays of the scalar glueball candidates f_0(1370),
f_0(1500) and f_0(1710) (a linear combination of sigma and H) into two pions in
an effective linear sigma model.Comment: 10 pages and 3 figures (an extended version of hep-ph/9805412), to
appear in Phys. Rev.
Survivin Selectively Modulates Genes Deregulated in Human Leukemia Stem Cells
ITD-Flt3 mutations are detected in leukemia stem cells (LSCs) in acute myeloid leukemia (AML) patients. While antagonizing Survivin normalizes ITD-Flt3-induced acute leukemia, it also impairs hematopoietic stem cell (HSC) function, indicating that identification of differences in signaling pathways downstream of Survivin between LSC and HSC are crucial to develop selective Survivin-based therapeutic strategies for AML. Using a Survivin-deletion model, we identified 1,096 genes regulated by Survivin in ITD-Flt3-transformed c-kit+, Sca-1+, and lineageneg (KSL) cells, of which 137 are deregulated in human LSC. Of the 137, 124 genes were regulated by Survivin exclusively in ITD-Flt3+ KSL cells but not in normal CD34neg KSL cells. Survivin-regulated genes in LSC connect through a network associated with the epidermal growth factor receptor signaling pathway and falls into various functional categories independent of effects on apoptosis. Pathways downstream of Survivin in LSC that are distinct from HSC can be potentially targeted for selective anti-LSC therapy
Accurate Charge-Dependent Nucleon-Nucleon Potential at Fourth Order of Chiral Perturbation Theory
We present the first nucleon-nucleon potential at
next-to-next-to-next-to-leading order (fourth order) of chiral perturbation
theory. Charge-dependence is included up to next-to-leading order of the
isospin-violation scheme. The accuracy for the reproduction of the NN data
below 290 MeV lab. energy is comparable to the one of phenomenological
high-precision potentials. Since NN potentials of order three and less are
known to be deficient in quantitative terms, the present work shows that the
fourth order is necessary and sufficient for a reliable NN potential derived
from chiral effective Lagrangians. The new potential provides a promising
starting point for exact few-body calculations and microscopic nuclear
structure theory (including chiral many-body forces derived on the same
footing).Comment: 4 pages Revtex including one figur
Measurement of neutron diffraction with compact neutron source RANS
Diffraction is used as a measurement technique for crystal structure. X-rays or electron beam with wavelength that is close to the lattice constant of the crystal is often used for the measurement. They have sensitivity in surface
(0.01mm) of heavy metals due to the mean free path for heavy ions. Neutron diffraction has the probe of the internal structure of the heavy metals because it has a
longer mean free path than that of the X-rays or the electrons. However, the neutron diffraction measurement is not widely used because large facilities are required in the many neutron sources. RANS (Riken Accelerator-driven Compact Neutron Source) is developed as a neutron source which is usable easily in laboratories and factories. In RANS, fast neutrons are generated by 7MeV protons colliding on a Be target. Some fast neutrons are moderated with polyethylene to thermal neutrons. The thermal neutrons of 10meV which have wavelength of 10nm can be used for the
diffraction measurement. In this study, the texture evolution in steels was measured with RANS and the validity of the compact neutron source was proved. The texture of IF steel sheets with the thickness of 1.0mm was measured with 10minutes run. The resolution is 2% and is enough to analyze a evolution in texture due to compression/tensile deformation or a volume fraction of two phases in the steel sample. These results have proven the possibility to use compact neutron source for the analysis of mesoscopic structure of metallic materials
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