12,183 research outputs found
The Role of Tensor Force in Heavy-Ion Fusion Dynamics
The tensor force is implemented into the time-dependent Hartree-Fock (TDHF)
theory so that both exotic and stable collision partners, as well as their
dynamics in heavy-ion fusion, can be described microscopically. The role of
tensor force on fusion dynamics is systematically investigated for
, ,
, , and
reactions which vary by the total number of
spin-unsaturated magic numbers in target and projectile. A notable effect on
fusion barriers and cross sections is observed by the inclusion of tensor
force. The origin of this effect is analyzed. The influence of isoscalar and
isovector tensor terms is investigated with the T forces. These effects of
tensor force in fusion dynamics are essentially attributed to the shift of
low-lying vibration states of colliding partners and nucleon transfer in the
asymmetric reactions. Our calculations of above-barrier fusion cross sections
also show that tensor force does not significantly affect the dynamical
dissipation at near-barrier energies
Locate QCD Critical End Point in a Continuum Model Study
With a modified chemical potential dependent effective model for the gluon
propagator, we try to locate the critical end point (CEP) of strongly
interacting matter in the framework of Dyson-Schwinger equations (DSE). Beyond
the chiral limit, we find that Nambu solution and Wigner solution could coexist
in some area. Using the CornwallJackiw-Tomboulis (CJT) effective action, we
show that these two phases are connected by a first order phase transition. We
then locate CEP as the end point of the first order phase transition line.
Meanwhile, based on CJT effective action, we give a direct calculation for the
chiral susceptibility and thereby study the crossover.Comment: 9 pages, 7 figures; Version published in JHE
Differential involvement of Wnt signaling in Bmp regulation of cancellous versus periosteal bone growth
Bone morphogenetic proteins (Bmp) are well-known to induce bone formation following chondrogenesis, but the direct role of Bmp signaling in the osteoblast lineage is not completely understood. We have recently shown that deletion of the receptor Bmpr1a in the osteoblast lineage with Dmp1-Cre reduces osteoblast activity in general but stimulates proliferation of preosteoblasts specifically in the cancellous bone region, resulting in diminished periosteal bone growth juxtaposed with excessive cancellous bone formation. Because expression of sclerostin (SOST), a secreted Wnt antagonist, is notably reduced in the Bmpr1a-deficient osteocytes, we have genetically tested the hypothesis that increased Wnt signaling might mediate the increase in cancellous bone formation in response to Bmpr1a deletion. Forced expression of human SOST from a Dmp1 promoter fragment partially rescues preosteoblast hyperproliferation and cancellous bone overgrowth in the Bmpr1a mutant mice, demonstrating functional interaction between Bmp and Wnt signaling in the cancellous bone compartment. To test whether increased Wnt signaling can compensate for the defect in periosteal growth caused by Bmpr1a deletion, we have generated compound mutants harboring a hyperactive mutation (A214V) in the Wnt receptor Lrp5. However, the mutant Lrp5 does not restore periosteal bone growth in the Bmpr1a-deficient mice. Thus, Bmp signaling restricts cancellous bone accrual partly through induction of SOST that limits preosteoblast proliferation, but promotes periosteal bone growth apparently independently of Wnt activation
The subordinated processes controlled by a family of subordinators and corresponding Fokker-Planck type equations
In this work, we consider subordinated processes controlled by a family of
subordinators which consist of a power function of time variable and a negative
power function of stable random variable. The effect of parameters in
the subordinators on the subordinated process is discussed. By suitable
variable substitutions and Laplace transform technique, the corresponding
fractional Fokker-Planck-type equations are derived. We also compute their mean
square displacements in a free force field. By choosing suitable ranges of
parameters, the resulting subordinated processes may be subdiffusive, normal
diffusive or superdiffusive.Comment: 11 pages, accepted by J. Stat. Mech.: Theor. Ex
Quantum state transmission in a cavity array via two-photon exchange
The dynamical behavior of a coupled cavity array is investigated when each
cavity contains a three-level atom. For the uniform and staggered intercavity
hopping, the whole system Hamiltonian can be analytically diagonalized in the
subspace of single-atom excitation. The quantum state transfer along the
cavities is analyzed in detail for distinct regimes of parameters, and some
interesting phenomena including binary transmission, selective localization of
the excitation population are revealed. We demonstrate that the uniform
coupling is more suitable for the quantum state transfer. It is shown that the
initial state of polariton located in the first cavity is crucial to the
transmission fidelity, and the local entanglement depresses the state transfer
probability. Exploiting the metastable state, the distance of the quantum state
transfer can be much longer than that of Jaynes-Cummings-Hubbard model. A
higher transmission probability and longer distance can be achieved by
employing a class of initial encodings and final decodings.Comment: 8 pages, 7 figures. to appear in Phys. Rev.
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