831 research outputs found
Nucleon magnetic moments in an extended chiral constituent quark model
We present results for the nucleon magnetic moments in the context of an
extended chiral constituent quark model based on the mechanism of the Goldstone
boson exchange, as suggested by the spontaneous breaking of chiral symmetry in
QCD. The electromagnetic charge-current operator is consistently deduced from
the model Hamiltonian, which includes all force components for the
pseudoscalar, vector and scalar meson exchanges. Thus, the continuity equation
is satisfied for each piece of the interaction, avoiding the introduction of
any further parameter. A good agreement with experimental values is found. The
role of isoscalar two-body operators, not constrained by the continuity
equation, is also investigated.Comment: 7 pages, 1 table, submitted for publication to Phys. Lett. B,
elsart.sty/elsart12.sty include
Charge-Exchange and multi-scattering effects in (e,e'n) knockout
Final-state interactions in (e,e'n) knockout reactions in the quasi-free
region are studied by considering the multistep direct scattering of the
ejectile nucleon. Primary and multiple particle emission are included within
the same model and are found to become important with increasing excitation
energy. Charge-exchange effects taken into account through the two-step
(e,e'p)(p,n) and three-step (e,e'p)(p,N)(N,n) processes are also found to
increase with energy. A comparison with the results obtained with an
isospin-dependent optical potential at small excitation energies is presented.Comment: 12 pages, 4 Postscript figures. A new section on multiple particle
emission added together with 2 new figures including primary and multiple
emission cross section
Stochastic Metallic-Glass Cellular Structures Exhibiting Benchmark Strength
By identifying the key characteristic “structural scales” that dictate the resistance of a porous metallic glass against buckling and fracture, stochastic highly porous metallic-glass structures are designed capable of yielding plastically and inheriting the high plastic yield strength of the amorphous metal. The strengths attainable by the present foams appear to equal or exceed those by highly engineered metal foams such as Ti-6Al-4V or ferrous-metal foams at comparable levels of porosity, placing the present metallic-glass foams among the strongest foams known to date
Compression-compression fatigue of Pd_(43)Ni_(10)Cu_(27)P_(20) metallic glass foam
Compression-compression fatigue testing of metallic-glass foam is performed. A stress-life curve is constructed, which reveals an endurance limit at a fatigue ratio of about 0.1. The origin of fatigue resistance of this foam is identified to be the tendency of intracellular struts to undergo elastic and reversible buckling, while the fatigue process is understood to advance by anelastic strut buckling leading to localized plasticity (shear banding) and ultimate strut fracture. Curves of peak and valley strain versus number of cycles coupled with plots of hysteresis loops and estimates of energy dissipation at various loading cycles confirm the four stages of foam-fatigue
Cluster Model for Near-barrier Fusion Induced by Weakly Bound and Halo Nuclei
The influence on the fusion process of coupling transfer/breakup channels is
investigated for the medium weight Li+Co systems in the vicinity
of the Coulomb barrier. Coupling effects are discussed within a comparison of
predictions of the Continuum Discretized Coupled-Channels model. Applications
to He+Co induced by the borromean halo nucleus He are also
proposed.Comment: 5 pages, 3 figures, FINUSTAR2 Conference, Aghios Nikolaus, Crete,
Greece. 10-14 September 200
Premitotic Labeling and Inflammation in the Gingiva of Rhesus Monkeys
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141674/1/jper0606.pd
Effect of strain rate on the yielding mechanism of amorphous metal foam
Stochastic amorphous Pd_(43)Ni_(10)Cu_(27)P_(20) foams were tested in quasistatic and dynamic loading. The strength/porosity relations show distinct slopes for the two loading conditions, suggesting a strain-rate-induced change in the foam yielding mechanism. The strength/porosity correlation of the dynamic test data along with microscopy assessments support that dynamic foam yielding is dominated by plasticity rather than elastic buckling, the mechanism previously identified to control quasistatic yielding. The strain-rate-induced shift in the foam yielding mechanism is attributed to the rate of loading approaching the rate of sound wave propagation across intracellular membranes, thereby suppressing elastic buckling and promoting plastic yielding
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