71,637 research outputs found
Can Universe Experience Many Cycles with Different Vacua ?
Recently, the notion that the number of vacua is enormous has received
increased attentions, which may be regarded as a possible anthropical
explanation to incredible small cosmological constant. Further, a dynamical
mechanisms to implement this possibility is required. We show in an operable
model of cyclic universe that the universe can experience many cycles with
different vacua, which is a generic behavior independent of the details of the
model. This might provide a distinct dynamical approach to an anthropically
favorable vacuum.Comment: RevTex, 10 pages, 4 eps figures, accepted by PRD(R), new title and
changes in the text to match publicatio
Quantum information storage and state transfer based on spin systems
The idea of quantum state storage is generalized to describe the coherent
transfer of quantum information through a coherent data bus. In this universal
framework, we comprehensively review our recent systematical investigations to
explore the possibility of implementing the physical processes of quantum
information storage and state transfer by using quantum spin systems, which may
be an isotropic antiferromagnetic spin ladder system or a ferromagnetic
Heisenberg spin chain. Our studies emphasize the physical mechanisms and the
fundamental problems behind the various protocols for the storage and transfer
of quantum information in solid state systems.Comment: 11 pages, 9 figures, Review article on the quantum spin based quantum
information processing, to appear the special issue of Low Temperature
Physics dedicated to the 70-th anniversary of creation of concept
"antiferromagnetism" in physics of magnetis
Liquid-liquid phase separation and morphology of internally mixed dicarboxylic acids/ammonium sulfate/water particles
Knowledge of the physical state and morphology of internally mixed organic/inorganic aerosol particles is still largely uncertain. To obtain more detailed information on liquid-liquid phase separation (LLPS) and morphology of the particles, we investigated complex mixtures of atmospherically relevant dicarboxylic acids containing 5, 6, and 7 carbon atoms (C5, C6 and C7) having oxygen-to-carbon atomic ratios (O:C) of 0.80, 0.67, and 0.57, respectively, mixed with ammonium sulfate (AS). With micrometer-sized particles of C5/AS/H_2O, C6/AS/H_2O and C7/AS/H_2O as model systems deposited on a hydrophobically coated substrate, laboratory experiments were conducted for various organic-to-inorganic dry mass ratios (OIR) using optical microscopy and Raman spectroscopy. When exposed to cycles of relative humidity (RH), each system showed significantly different phase transitions. While the C5/AS/H_2O particles showed no LLPS with OIR = 2:1, 1:1 and 1:4 down to 20% RH, the C6/AS/H_2O and C7/AS/H_2O particles exhibit LLPS upon drying at RH 50 to 85% and ~90%, respectively, via spinodal decomposition, growth of a second phase from the particle surface or nucleation-and-growth mechanisms depending on the OIR. This suggests that LLPS commonly occurs within the range of O:C < 0.7 in tropospheric organic/inorganic aerosols. To support the comparison and interpretation of the experimentally observed phase transitions, thermodynamic equilibrium calculations were performed with the AIOMFAC model. For the C7/AS/H_2O and C6/AS/H_2O systems, the calculated phase diagrams agree well with the observations while for the C5/AS/H_2O system LLPS is predicted by the model at RH below 60% and higher AS concentration, but was not observed in the experiments. Both core-shell structures and partially engulfed structures were observed for the investigated particles, suggesting that such morphologies might also exist in tropospheric aerosols
VISHNU hybrid model for viscous QCD matter at RHIC and LHC energies
In this proceeding, we briefly describe the viscous hydrodynamics + hadron
cascade hybrid model VISHNU for relativistic heavy ion collisions and report
the current status on extracting the QGP viscosity from elliptic flow data.Comment: 4 pages, 1 figure, the proceedings of 7th International Workshop on
Critical Point and Onset of Deconfinement, Wuhan, China, Nov. 7-11, 201
Quark Orbital Angular Momentum in the Baryon
Analytical and numerical results, for the orbital and spin content carried by
different quark flavors in the baryons, are given in the chiral quark model
with symmetry breaking. The reduction of the quark spin, due to the spin
dilution in the chiral splitting processes, is transferred into the orbital
motion of quarks and antiquarks. The orbital angular momentum for each quark
flavor in the proton as a function of the partition factor and the
chiral splitting probability is shown. The cancellation between the spin
and orbital contributions in the spin sum rule and in the baryon magnetic
moments is discussed.Comment: 26 pages, 3 figures, revised version with minor eq. no and ref. no.
corrections. Discussion on the spin and a new ref. are adde
Fuzzy Recommendations in Marketing Campaigns
The population in Sweden is growing rapidly due to immigration. In this
light, the issue of infrastructure upgrades to provide telecommunication
services is of importance. New antennas can be installed at hot spots of user
demand, which will require an investment, and/or the clientele expansion can be
carried out in a planned manner to promote the exploitation of the
infrastructure in the less loaded geographical zones. In this paper, we explore
the second alternative. Informally speaking, the term Infrastructure-Stressing
describes a user who stays in the zones of high demand, which are prone to
produce service failures, if further loaded. We have studied the
Infrastructure-Stressing population in the light of their correlation with
geo-demographic segments. This is motivated by the fact that specific
geo-demographic segments can be targeted via marketing campaigns. Fuzzy logic
is applied to create an interface between big data, numeric methods for
processing big data and a manager.Comment: conferenc
Theoretical studies of 63Cu Knight shifts of the normal state of YBa2Cu3O7
The 63Cu Knight shifts and g factors for the normal state of YBa2Cu3O7 in
tetragonal phase are theoretically studied in a uniform way from the high
(fourth-) order perturbation formulas of these parameters for a 3d9 ion under
tetragonally elongated octahedra. The calculations are quantitatively
correlated with the local structure of the Cu2+(2) site in YBa2Cu3O7. The
theoretical results show good agreement with the observed values, and the
improvements are achieved by adopting fewer adjustable parameters as compared
to the previous works. It is found that the significant anisotropy of the
Knight shifts is mainly attributed to the anisotropy of the g factors due to
the orbital interactions.Comment: 5 page
Investigations of the g factors and local structure for orthorhombic Cu^{2+}(1) site in fresh PrBa_{2}Cu_{3}O_{6+x} powders
The electron paramagnetic resonance (EPR) g factors g_x, g_y and g_z of the
orthorhombic Cu^{2+}(1) site in fresh PrBa_{2}Cu_{3}O_{6+x} powders are
theoretically investigated using the perturbation formulas of the g factors for
a 3d^9 ion under orthorhombically elongated octahedra. The local orthorhombic
distortion around the Cu^{2+}(1) site due to the Jahn-Teller effect is
described by the orthorhombic field parameters from the superposition model.
The [CuO6]^{10-} complex is found to experience an axial elongation of about
0.04 {\AA} along c axis and the relative bond length variation of about 0.09
{\AA} along a and b axes of the Jahn-Teller nature. The theoretical results of
the g factors based on the above local structure are in reasonable agreement
with the experimental data.Comment: 6 pages, 1 figur
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