13,634 research outputs found
A finite element method for time fractional partial differential equations
This is the authors' PDF version of an article published in Fractional calculus and applied analysis© 2011. The original publication is available at www.springerlink.comThis article considers the finite element method for time fractional differential equations
Chiral Perturbation Theory and U(3)_L\times U(3)_R Chiral Theory of Mesons
We examine low energy limit of chiral theory of mesons
through integrating out fields of vector and axial-vector mesons. The effective
lagrangian for pseudoscalar mesons at has been obtained, and five low
energy coupling constants have been revealed. They are in
good agreement with the results of CHPT's at .Comment: 20 pages, Standard LaTex file, no finger
Current rectification by asymmetric molecules: An ab initio study
We study current rectification effect in an asymmetric molecule
HOOC-CH-(CH) sandwiched between two Aluminum electrodes using
an {\sl ab initio} nonequilibrium Green function method. The conductance of the
system decreases exponentially with the increasing number of CH. The
phenomenon of current rectification is observed such that a very small current
appears at negative bias and a sharp negative differential resistance at a
critical positive bias when . The rectification effect arises from the
asymmetric structure of the molecule and the molecule-electrode couplings. A
significant rectification ratio of 38 can be achieved when .Comment: to appear in J. Chem. Phy
Exotic phase diagram of a topological quantum system
We study the quantum phase transitions (QPTs) in the Kitaev spin model on a
triangle-honeycomb lattice. In addition to the ordinary topological QPTs
between Abelian and non-Abelian phases, we find new QPTs which can occur
between two phases belonging to the same topological class, namely, either two
non-Abelian phases with the same Chern number or two Abelian phases with the
same Chern number. Such QPTs result from the singular behaviors of the nonlocal
spin-spin correlation functions at the critical points.Comment: 10 pages, 5 figure
Interdimensional degeneracies for a quantum -body system in dimensions
Complete spectrum of exact interdimensional degeneracies for a quantum
-body system in -dimensions is presented by the method of generalized
spherical harmonic polynomials. In an -body system all the states with
angular momentum in dimensions are degenerate where
and are given and is an arbitrary integer if the representation
exists for the SO() group and . There is an
exceptional interdimensional degeneracy for an -body system between the
state with zero angular momentum in dimensions and the state with zero
angular momentum in dimensions.Comment: 8 pages, no figure, RevTex, Accepted by EuroPhys.Let
Experimental Realization of Br\"{u}schweiler's exponentially fast search algorithm in a homo-nuclear system
Compared with classical search algorithms, Grover quantum algorithm [ Phys.
Rev. Lett., 79, 325(1997)] achieves quadratic speedup and Bruschweiler hybrid
quantum algorithm [Phys. Rev. Lett., 85, 4815(2000)] achieves an exponential
speedup. In this paper, we report the experimental realization of the
Bruschweiler$ algorithm in a 3-qubit NMR ensemble system. The pulse sequences
are used for the algorithms and the measurement method used here is improved on
that used by Bruschweiler, namely, instead of quantitatively measuring the spin
projection of the ancilla bit, we utilize the shape of the ancilla bit
spectrum. By simply judging the downwardness or upwardness of the corresponding
peaks in an ancilla bit spectrum, the bit value of the marked state can be read
out, especially, the geometric nature of this read-out can make the results
more robust against errors.Comment: 10 pages and 3 figure
Toward a comprehensive understanding of eye-level urban greenness: a systematic review
The provision of urban green spaces has been widely acknowledged to offer numerous benefits to individuals and communities. Recently, there has been a growing recognition of the importance of evaluating urban greenness from a human-centered perspective, partly due to the rapid development of eye-level greenness measurement. To provide a comprehensive overview of measurement approaches and topics related to eye-level urban greenness, we conducted a systematic review of 77 relevant papers. Our review revealed that street view images are the primarily utilized data source to quantify eye-level urban greenness in urban analysis. Additionally, simulated eye-level urban greenness represents a new frontier for the general public and urban planners, offering the potential to acquire universally applicable quantitative greenness data. Our findings further suggest that eye-level urban greenness has been explored across various domains, including physical behavior, public health, urban planning, human perception, and inequity. Such exploration has highlighted a significant association between eye-level urban greenness and individuals and communities. Our review generates new insights on the integration of urban greenness into urban planning and design, encouraging a greater focus on eye-level urban greenness as a critical component of urban environmental quality
Topological insulators in filled skutterudites
We propose new topological insulators in cerium filled skutterudite (FS)
compounds based on ab initio calculations. We find that two compounds CeOs4As12
and CeOs4Sb12 are zero gap materials with band inversion between Os-d and Ce-f
orbitals, which are thus parent compounds of two and three-dimensional
topological insulators just like bulk HgTe. At low temperature, both compounds
become topological Kondo insulators, which are Kondo insulators in the bulk,
but have robust Dirac surface states on the boundary. This new family of
topological insulators has two advantages compared to previous ones. First,
they can have good proximity effect with other superconducting FS compounds to
realize Majarona fermions. Second, the antiferromagnetism of CeOs4Sb12 at low
temperature provides a way to realize the massive Dirac fermion with novel
topological phenomena.Comment: 4 page, 3 figure
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