This paper studies the evolutionary prisoner's dilemma game on a highly clustered community network in which the clustering
coefficient and the community size can be tuned. It finds that the clustering coefficient in such a degree-homogeneous network inhibits the emergence of cooperation for the entire range of the payoff parameter. Moreover, it finds that the community size can also have a marked influence on the evolution of cooperation, with a larger community size leading to not only a lower cooperation level but also a smaller threshold of the payoff parameter above which cooperators become extinct.

A novel method for obtaining the approximate symmetry of a partial differential equation with a small parameter is introduced. By expanding the independent variable and the dependent variable in the small parameter series, we obtain more affluent approximate symmetries. The method is applied to two perturbed nonlinear partial differential equations and new approximate solutions are derived.

This paper presents a method to find Noether-type conserved quantities and Lie point symmetries for discrete mechanico-electrical dynamical systems, which leave invariant the set of solutions of the corresponding difference scheme. This
approach makes it possible to devise techniques for solving the Lagrange--Maxwell equations in differences which correspond to mechanico-electrical systems, by adapting existing differential equations. In particular, it obtains a new systematic method to determine both the one-parameter Lie groups and the discrete Noether conserved quantities of Lie point symmetries for mechanico-electrical systems. As an application, it obtains the Lie point symmetries and the conserved quantities for the difference equation of a model that represents a capacitor microphone.

This paper proposes a method to measure directly the concurrence of an arbitrary two-qubit pure state based on a generalized Grover quantum iteration algorithm and a phase estimation algorithm. The concurrence can be calculated by applying quantum algorithms to two available copies of the bipartite system, and a final measurement on
the auxiliary working qubits gives a better estimation of the concurrence. This method opens new prospects of entanglement measure by the application of quantum algorithms. The implementation of the protocol would be an important step toward quantum information processing and more complex entanglement measure of the finite-dimensional quantum system with an arbitrary number of qubits.

This paper derives the analytical expression of free energy for a weakly interacting Fermi gas in a weak magnetic field, by using the methods of quantum statistics as well as considering the relativistic effect. Based on the derived expression, the thermodynamic properties of the system at both high and low temperatures are given and the relativistic effect on the properties of the system is discussed. It shows that, in comparison with a nonrelativistic situation, the relativistic effect changes the influence of temperature on the thermodynamic properties of the system at high temperatures, and changes the influence of particle-number density on them at extremely low temperature. But the relativistic effect does not change the influence of the magnetic field and inter-particle interactions on the thermodynamic properties of the system at both
high and extremely low temperatures.

A matrix eigenvalue method is applied to analyse the thermodynamic stability of two-component interacting fermions. The
non-relativistic and ultra-relativistic d=1, 2,3 dimensions have been discussed in detail, respectively. The corresponding stability region has been given according to the two-body interaction strength and the particle number density ratio.

The dynamics of a dark soliton has been investigated in a Bose--Einstein
condensate with an external magnetic trap, and the effects of localized
impurity on the dynamics are discussed by the variational approach
based on the renormalized integrals of motion. The reciprocal
movement of the dark soliton is discussed by performing a standard
linear analysis, and it is found that the effects of the localized
impurity depend strictly on the positive or negative value of the
impurity strength corresponding to the repulsive or attractive
impurity. The numerical results confirm the theoretical analysis,
and show that the effects also depend on the effective nonlinear
coefficient and the harmonic frequency.

This paper investigates the parameter-induced stochastic resonance using experimental methods in an over-damped random linear system with asymmetric dichotomous noise. Non-monotonic dependence of signal-to-noise ratio on the system parameter is observed. Several potential applications of parameter-induced stochastic resonance are given in circuits.

In this paper, a novel hyperchaotic system with one nonlinear term and its fractional order system are proposed. Furthermore, synchronization between two fractional-order systems with different fractional-order values is achieved. The proposed synchronization scheme is simple and theoretically rigorous. Numerical simulations are in agreement with the theoretical analysis.

This paper presents a new 3D quadratic autonomous chaotic system which contains five system parameters and three quadratic
cross-product terms, and the system can generate a single four-wing chaotic attractor with wide parameter ranges. Through
theoretical analysis, the Hopf bifurcation processes are proved to arise at certain equilibrium points. Numerical bifurcation analysis shows that the system has many interesting complex dynamical behaviours; the system trajectory can evolve to a chaotic attractor from a periodic orbit or a fixed point as the proper parameter varies. Finally, an analog electronic circuit is designed to physically realize the chaotic system; the existence of four-wing chaotic attractor is verified by the analog circuit realization.

In a recent paper [2002 Phys. Rev. Lett.88 174102], Bandt and Pompe propose permutation entropy (PE) as a natural complexity measure for arbitrary time series which may be stationary or nonstationary, deterministic or stochastic. Their method is based on a comparison of neighbouring values. This paper further develops PE, and proposes the concept of fine-grained PE (FGPE) defined by the order pattern and magnitude of the difference between neighbouring values. This measure excludes the case where vectors with a distinct appearance are mistakenly mapped onto the same permutation type, and consequently FGPE becomes more sensitive to the dynamical change of time series than does PE, according to our simulation and experimental results.

We use a new updated algorithm scheme to investigate the critical behaviour of the two-dimensional ferromagnetic Ising model on a triangular lattice with the nearest neighbour interactions. The transition is examined by generating accurate data for lattices with L= 8, 10, 12, 15, 20, 25, 30, 40 and 50. The updated spin algorithm we employ has the advantages of both a Metropolis algorithm and a single-update method. Our study indicates that the transition is continuous at T_{c}= 3.6403({2}). A convincing finite-size scaling analysis of the model yields υ=0.9995(21), β /
υ = 0.12400({17}), γ / υ = 1.75223(22), γ '/υ=1.7555(22), α/υ= 0.00077(420) (scaling) and α / υ = 0.0010(42) (hyperscaling). The present scheme yields more accurate estimates for all the critical exponents than the Monte Carlo method, and our estimates are shown to be in excellent agreement with their predicted values.

This paper proposes a new traffic model to describe traffic flow
with slope under consideration of the gravity effect. Based on the model,
stability analysis is conducted and a numerical simulation is
performed to explore the characteristics of the traffic flow with
slope. The result shows that the perturbation of the system is
an inherent one, which is induced by the slope. In addition, the
hysteresis loop is represented through plotting the figure of
velocity against headway and highly depends on the slope angle. The
kinematic wave at high density is also obtained through reproducing
the phenomenon of stop-and-go traffic, which is significant to
explore the phase transition of traffic flow and the evolution of
traffic congestion.

The equilibrium geometries and electronic properties of Au_{n}Al,
up to n=13, have been systematically investigated using the density
functional theory. The results show that, for the Au_{n}Al
clusters, two patterns are identified. Pattern one (n=2, 3, 8),
the lowest-energy geometries prefer two-dimensional structures.
Pattern two (n=4-7, 9--13), the lowest-energy geometries prefer
three-dimensional structures. According to the analysis of the
binding energy and the fragmentation energy, Au_{n}Al clusters
with odd n are found to be more stable than those with even n.
The same trend of alternation can be illuminated according to the
computational results in the HOMO--LUMO gap, the ionization
potential, and the electron affinities. The Al atom not only changes
the structures of pure gold clusters, but also enhances their
stabilities. NBO analysis indicates 6s orbital of Au atom hybridizes
with 3p orbital of Al atom.

The dynamical entanglement for Fermi coupled C--H stretch and bend
vibrations in molecule CHD_{3} is studied in terms of two
negativities and the reduced von Neumann entropy, where initial
states are taken to be direct products of photon-added coherent
states on each mode. It is demonstrated that the negativity defined
by the sum of negative eigenvalues of the partial transpose of
density matrices is positively correlated with the von Neumann
entropy. The entanglement difference between photon-added coherent
states and usual coherent states is discussed as well.

This paper studies the isotopic effect of Cl_{2}^{+} rovibronic
spectra in the A^{2}П_{u} (Ω = 1/2) - X^{2}П_{g}(Ω= 1/2) system. Based on the experimental results of the molecular constants of ^{35}Cl_{2}^{+}, it calculates the
vibrational isotope shifts of the (2, 7) and (3, 7) band between the
isotopic species ^{35}Cl_{2}^{+}, ^{35}Cl^{37}Cl^{+}
and ^{37}Cl_{2}^{+}, and estimates the rotational constants of
both A^{2}П_{u} and X ^{2}П_{g} states for the
minor isotopic species ^{35}Cl^{37}Cl^{+} and ^{37}Cl_{2}^{+}. The experimental results of the spectrum of ^{35}Cl^{37}Cl^{+} (3, 7) band proves the above mentioned
theoretical calculation. The molecular constants and thus resultant rovibronic spectrum for ^{37}Cl_{2}^{+} were predicted, which will be helpful for further experimental investigation.

This paper studies the near transform-limited high-resolution
tunable far-ultraviolet light which is generated by narrow-band
tunable light both theoretically and experimentally. It presents the
theoretical work on conversion efficiency of sum-frequency, which
is restricted by phase-matching angle, walk-off angle and phase
distortion and so on, and conducts an experiment to check this work
successfully. Also the origin of chirp of a dye laser is analysed.

This paper reports how pyrite films were prepared by thermal
sulfurization of magnetron sputtered iron films and characterized by
x-ray absorption near edge structure spectra and x-ray photoelectron
spectroscopy on a 4B9B beam line at the Beijing Synchrotron Radiation
Facility. The band gap of the pyrite agrees well with the optical
band gap obtained by a spectrophotometer. The octahedral symmetry of
pyrite leads to the splitting of the d orbit into t_{\rm 2g} and
e_{\rm g} levels. The high spin and low spin states were analysed
through the difference of electron exchange interaction and the orbital
crystal field. Only when the crystal field splitting is higher than
1.5 eV, the two weak peaks above the white lines can appear, and this
was approved by experiments in the present work.

The transmissions of oxygen ions through Al_{2}O_{3}
nanocapillaries each 50~nm in diameter and 10~μ m in length
at a series of different tilt angles are measured, where the ions
with energies ranging from 10 to 60~keV and charge states from 1 up
to 6 are involved. The angular distribution and the transmission
yields of transported ions are investigated. Our results indicate
both the existence of a guiding effect when ions pass through the
capillary and a significant dependence of the ion transmission on
the energy and the charge state of the ions. The guiding effects are
observed to be enhanced at lower projectile energies and higher
charge states. Meanwhile, the results also exhibit that the
transmission yields increase as the tilt angle decreases at a given
energy and charge state.

This paper presents the fully differential cross sections (FDCS) for
102eV electron impact single ionization of helium for both the
coplanar and perpendicular plane asymmetric geometries within the
framework of dynamically screened three-Coulomb-wave theory.
Comparisons are made with the experimental data and those of the
three-Coulomb wave function model and second-order distorted-wave
Born method. The angular distribution and relative heights of the
present FDCS is found to be in very good agreement with the
experimental data in the perpendicular plane geometry. It is shown
that dynamical screening effects are significant in this geometry.
Three-body coupling is expected to be weak in the coplanar geometry,
although the precise absolute value of the cross section is still
sensitive to the interaction details.

This paper investigates the properties of traveling wave-beam
interaction in a rectangular helix traveling-wave-tube (TWT) for a
solid sheet electron beam. The `hot' dispersion equation is obtained
by means of the self-consistent field theory. The small signal
analysis, which includes the effects of the beam parameters and
slow-wave structure (SWS) parameters, is carried out by
theoretical computation. The numerical results show that the
bandwidth and the small-signal gain of the rectangular helix TWT
increase as the beam current increases; and the beam voltage not obviously
influences the small signal gain. Among different
rectangular helix structures, the small-signal gain increases as the
width of the rectangular helix SWS increases, however, the bandwidth
decreases whether structure parameters a and L or ψ and L
are fixed or not. In addition, a comparison of the small-signal gain
of this structure with a conventional round helix is made. The
presented analysis will be useful for the design of the TWT with a
rectangular helix circuit.

Composite electromagnetic scattering from a two-dimensional (2D)
ship-like target on a one-dimensional sea surface is investigated by
using the finite-difference time-domain (FDTD) method. A uniaxial
perfectly matched layer is adopted for truncation of FDTD lattices.
The FDTD updated equations can be used for the total computation
domain by choosing the uniaxial parameters properly. To validate the
proposed numerical technique, a 2D infinitely long cylinder over the
sea surface is taken into account first. The variation of angular
distribution of the scattering changing with incident angle is
calculated. The results show good agreement with the conventional moment
method. Finally, the influence of the incident angle, the
polarization, and the size of the ship-like target on the composite
scattering coefficient is discussed in detail.

This paper proposes a new method of aperture synthetizing in digital
holography based on the principle of holography. In the new method
aperture synthetizing is achieved by reconstructing each
sub-hologram respectively, firstly, moving each reconstructed wave
field referred to the benchmark reconstructed wave field according
to the relationship between spacial motion and frequency shift, and
finally splicing them by using superposition. Two different
recording ways, using plane wave to record and using spherical wave
to record, are analyzed, and their moving formula is deduced, too.
Simulation and experiment are done. The results show that in
comparison with the traditional method of aperture synthetizing in
digital holography, the new method can decrease calculation and save
reconstructed time obviously which has better applicability.

This paper analyses the dynamic residual aberrations of a
conformal optical system and introduces adaptive optics (AO)
correction technology to this system. The image sharpening AO system
is chosen as the correction scheme. Communication between MATLAB and
Code V is established via ActiveX technique in computer simulation.
The SPGD algorithm is operated at seven zoom positions to
calculate the optimized surface shape of the deformable mirror.
After comparison of performance of the corrected system with the
baseline system, AO technology is proved to be a good way of
correcting the dynamic residual aberration in conformal optical
design.

The segmented mirror telescope is widely used. The aberrations of
segmented mirror systems are different from single mirror systems.
This paper uses the Fourier optics theory to analyse the Zernike
aberrations of segmented mirror systems. It concludes that the
Zernike aberrations of segmented mirror systems obey the linearity
theorem. The design of a segmented space telescope and segmented
schemes are discussed, and its optical model is constructed. The
computer simulation experiment is performed with this optical model
to verify the suppositions. The experimental results confirm the
correctness of the model.

This paper introduces Lorentz beams to describe certain laser
sources that produce highly divergent fields. The fractional Fourier
transform (FRFT) is applied to treat the propagation of Lorentz
beams. Based on the definition of convolution and the convolution
theorem of the Fourier transform, an analytical expression for a
Lorentz beam passing through a FRFT system has been derived. By
using the derived formula, the properties of a Lorentz beam in the
FRFT plane are illustrated numerically.

This paper reports a new way to detect the enhanced transmission of a
THz electromagnetic wave through an Ag/Ag_{2}O layer by THz-TDS
(time-domain spectroscopy). As the THz beam illuminates the
sub-wavelength Ag particles gained by Ag_{2}O thermal
decomposition, the evanescent wave is generated. The evanescent wave
is coupled by a 500μ m-GaAs substrate, which attaches behind the
Ag/Ag_{2}O layer, and then it transmits to the far field to be
detected. The experimental results indicate that the transmitting
amplitude is enhanced, as well as the frequent shifting and spectra
broadening.

This paper studies the dispersion effect of the supersphere solid
immersion lens (SIL) on a near field optical microscopy system by
using the vector diffraction theory. Results show that when a real
non-monochromatic beam illuminates a supersphere SIL microscopy, the
dispersion effect of the SIL has an important influence on the image
quality. As the wavelength bandwidth of the non-monochromatic beam
increases, the size of the focused spot increases and its intensity
decreases in near-field microscopy systems with a supersphere SIL.

This paper investigates the entropy squeezing of a moving two-level
atom interacting with the two-mode entangled coherent field via
two-photon transition by using an entropic uncertainty relation and the
degree of entanglement between the two-mode fields by using quantum
relative entropy. The results obtained from numerical calculation
indicate that the squeezed period, the duration of entropy squeezing
and the maximal squeezing can be controlled by appropriately
choosing the intensity of the light field, the atomic motion and the
field-mode structure. The atomic motion leads to the periodic
recovery of the initial maximal degree of entanglement between the
two-mode fields. Moreover, there exists a corresponding relation
between the time evolution properties of the atomic entropy
squeezing and those of the entanglement between the two-mode fields.

A new type of all-fibre Sagnac interferometer composed of two loops
is proposed and analysed in detail. It can be used with a very long
transmission line while maintaining excellent performance
characteristics due to the automatic compensation of any
birefringence effects in the trunk fibre. Preliminary experiments at
1310~nm wavelength with a 70~km long trunk fibre demonstrated an
interference visibility as high as 98%, indicating that this
scheme has promising potential applications.

Spherical aberrations of the thermal lens of the active media are severe
when solid state lasers are strongly pumped. The fundamental mode
profile deteriorates due to the aberrations. Self-consistent
modes of a resonator with aberrations are calculated by using the
Fox--Li diffraction iterative algorithm. Calculation results show
that the aberration induced fundamental mode beam quality
deterioration depends greatly on the resonator design. The tolerance
of a flat--flat resonator to the aberration coefficient is about
30λ in the middle of stability, where λ is the
wavelength of laser beam. But for a dynamically stable resonator,
2λ of spherical aberration will create diffraction loss of
more than 40%, if inappropriate design criteria are used. A
birefringence compensated laser resonator with two Nd:YAG rods is
experimentally studied. The experimental data are in quite good
agreement with simulation results.

This paper studies the interactions between two and more adjacent
chirped soliton-like pulses, respectively. The results show that the
pulses present strong interactions when the separations between them
are smaller than a certain value, and their behaviour is very
distinct under different conditions, such as a different number of
pulses or different initial separations between them. Furthermore,
we also study the suppression of these interactions and obtain
very good effects by using different initial amplitude ratios.

Exact solutions of Gaussian solitons in nonlinear media with a
Gaussian nonlocal response are obtained. Using the variational
approach, we obtain the approximate solutions of such solitons when
the degree of the nonlocality is arbitrary. Specifically, we study
the conditions for Gaussian solitons that propagate in weakly
and highly nonlocal media. We also compare the variational result
with the known exact solutions for weakly and highly nonlocal media.

Nonlinear refractive properties of chloroaluminum phthalocyanine
(CAP) in ethanol solution are studied using the Z-scan
technique with picosecond (ps) and nanosecond (ns) laser pulses at a
wavelength of 532 nm. A transition from self-focusing to
self-defocusing in CAP solution excited by 10 ns pulses is observed
during the decrease of its concentration. This transition is due to
co-existing excited-state refraction and transient thermal lensing
effects. The experimental results are described very well using
the rate-equation model and the theory of transient thermal
refraction in liquids. The refractive cross sections of the
excited-state are also obtained.

This paper investigates the effect of beam divergence angle on
output waveform based on stimulated Brillouin scattering optical
limiting. Output waveforms in the case of different pump divergence
angles are numerically simulated, and validated in a Nd:YAG
seed-injected laser system. The results indicate that a small pump
divergence angle can lead to good interaction between pump and
Stokes, and a platform can be easily realized in the transmitted
waveform. In contrast, a peak followed by the platform appears when
the divergence angle becomes large.

Based on the time-dependent band-transport model in a photorefractive medium, dark open-circuit photovoltaic (PV) solitons are investigated both theoretically and experimentally. Compared with those of the time-independent models, our theoretical results revealed that quasi-steady-state and steady-state PV solitons can both be obtained. Our results also revealed that when r < 1 (r is the normalized intensity at infinity), the full width at half maximum (FWHM) of solitons decreases monotonically to a constant value; when r > 1, however, the FWHM of solitons first decreases to a minimum before it increases to a constant value. Moreover, the FWHM of steady solitons decreases with increasing intensity ratio
for r < 1, and increases with increasing intensity ratio for r > 1. We further observed dark PV solitons in experiments, and recorded their evolution. These results indicated that steady solitons can be observed at low optical power, while
quasi-steady-state solitons can only be generated at higher optical power. Good agreement is found between theory and experiment.

This paper investigates the performances of terahertz-wave
parametric oscillators (TPOs) based on the LiNbO_{3} crystal at
different pump wavelengths. The calculated results show that TPO
characteristics, including the frequency tuning range, the THz-wave
gain and the stability of THz-wave output direction based on the
Si-prism coupler, can be significantly improved by using a
short-wavelength pump. It also demonstrates that a
long-wavelength-pump allows the employment of a short TPO cavity due
to an enlarged phase-matching angle, that is, an increased angular
separation between the pump and oscillated Stokes beams under the
THz-wave generation at a specific frequency. The study provides an
useful guide and a theoretical basis for the further improvement of
TPO systems.

The physical features exhibited by Hermite--Gaussian (HG) beams
propagating in nonlocal nonlinear media with Gaussian-shaped
response are discussed with an approximate variational method. Using
direct numerical simulations, we find that the beam properties in
the normalized system are different with the change of the degree of
nonlocality. It is shown that initial HG profiles break up into
several individual beams with propagation when the degree of
nonlocality α is small. HG beams can propagate stably when
α is large enough.

This paper studies the photosensitive effect of cerium oxide on the
precipitation of Ag nanoparticles after femtosecond laser
irradiating into silicate glass and successive annealing.
Spectroscopy analysis and diffraction efficiency measurements show
that the introduction of cerium oxide may increase the concentration
of Ag atoms in the femtosecond laser-irradiated regions resulting
from the photoreduction reaction Ce^{3+} + Ag^{+} \to
Ce^{3+} + Ag^{0} via multiphoton excitation. These results
promote the aggregation of Ag nanoparticles during the annealing
process. It is also found that different concentrations of cerium oxide
may influence the Ag nanoparticle precipitation in the
corresponding glass.

One-dimensional photonic crystal structures for multiple channeled
filtering and polarization selective filtering in the terahertz
(THz) range are studied theoretically. The design of aperiodic photonic
quantum-well (APQW) structures for multiple channeled filtering and
different polarization filtering at arbitrary preassigned
frequencies are achieved by using the simulated annealing algorithm
with a special merit function. The parameters of these filters can
be expediently controlled and the transmission characters are
polarization dependent. Numerical simulations show that the designed
APQWs can meet the desired specification well.

This paper reports that the complex-coupled distributed feedback
laser with the sampled grating has been designed and fabricated. The
+1st order reflection of the sampled grating is utilized for
laser single mode operation, which is 1.5387~μ m in the
experiment. The typical threshold current of the device is 30~mA,
and the optical output power is about 10~mW at the injection current
of 100~mA.

This paper uses the weakly nonlinear method and perturbation method
to deal with the quasi-geostrophic vorticity equation, and the
modified Korteweg-de Vries(mKdV) equations describing the evolution
of the amplitude of solitary Rossby waves as the change of Rossby
parameter β(y) with latitude y is obtained.

The rolling massage is one of the most important manipulations in
Chinese massage, which is expected to eliminate many diseases. Here,
the effect of the rolling massage on a pair of particles moving in
blood vessels under rolling massage manipulation is studied by
the lattice Boltzmann simulation. The simulated results show that
the motion of each particle is considerably modified by the
rolling massage, and it depends on the relative
rolling velocity, the rolling depth, and the distance between
particle position and rolling position. Both particles'
translational average velocities increase almost linearly as
the rolling velocity increases, and obey the same law. The increment of
the average relative angular velocity for the leading particle is
smaller than that of the trailing one. The result is helpful for
understanding the mechanism of the massage and to further develop the
rolling techniques.

CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES

This paper investigates the average dielectric permittivity
(\overline ε ) in the Maier--Meier theory for calculating
the dielectric anisotropy (Δε) of nematic liquid
crystals. For the reason that \overline ε of nematics
has the same expression as the dielectric permittivity of the isotropic
state, the Onsager equation for isotropic dielectric was used to
calculate it. The computed \overline ε shows reasonable
agreement with the results of the numerical methods used in the
literature. Molecular parameters, such as the polarizability and its
anisotropy, the dipole moment and its angle with the molecular long
axis, were taken from semi-empirical quantum chemistry (MOCPAC/AM1)
modeling. The calculated values of Δε according
to the Maier--Meier equation are in good agreement with the experimental
results for the investigated compounds having different core
structures and polar substituents.

We have grown underdoped (x = 0.11, 0.12) and optimally doped (x
= 0.16) La_{2-x}Sr_{x}CuO_{4} single crystals by the
traveling-solvent floating-zone technique. In order to prepare good quality
cuprate crystals, we have made much effort to optimize the preparation procedures.
For example, we haveadopted the sol--gel route to prepare a highly
fine and homogeneous La_{2-x}Sr_{x}CuO_{4} precursor powder for fabricating a very dense
ceramic feed rod used for the floating-zone growth, and we have also used
quite a slow growth rate. The high quality of the grown crystals
has been verified by double-crystal x-ray rocking curves, with the
full-width-at-half-maximum being only 113--150 arcseconds, which are
the best data reported so far for La_{2-x}Sr_{x}CuO_{4}
crystals. The superconducting critical temperatures of the grown
crystals are 30, 31 and 38.5~K for x = 0.11, 0.12 and 0.16
samples, respectively, according to magnetic measurements.

The melting curve of Sn has been calculated using the
dislocation-mediated melting model with the `zone-linking method'.
The results are in good agreement with the experimental data. According
to our calculation, the melting temperature of γ -Sn at zero
pressure is about 436~K obtained by the extrapolation of the method
from the triple point of Sn. The results show that this calculation
method is better than other theoretical methods for predicting the
melting curve of polymorphic material Sn.

Based on Duan's topological current theory, we propose a novel
approach to study the topological properties of topological defects
in a two-dimensional complex vector order parameter system. This
method shows explicitly the fine topological structure of defects.
The branch processes of defects in the vector order parameter system
have also been investigated with this method.

Dislocations are thought to be the principal mechanism of high
ductility of the novel B2 structure intermetallic compounds YAg and
YCu. In this paper, the edge dislocation core structures of two
primary slip systems <100>{010} and
<100>{01\overline{1}} for YAg and YCu are presented
theoretically within the lattice theory of dislocation. The
governing dislocation equation is a nonlinear integro-differential
equation and the variational method is applied to solve the
equation. Peierls stresses for <100>{010} and
<100>{01\overline{1}} slip systems are calculated
taking into consideration the contribution of the elastic strain
energy. The core width and Peierls stress of a typical
transition-metal aluminide NiAl is also reported for the purpose of
verification and comparison. The Peierls stress of NiAl obtained here is
in agreement with numerical results, which verifies the
correctness of the results obtained for YAg and YCu. Peierls stresses of the
<100>{01\overline{1}} slip system are smaller than
those of <100>{010} for the same intermetallic
compounds originating from the smaller unstable stacking fault
energy. The obvious high unstable stacking fault energy of NiAl
results in a larger Peierls stress than those of YAg and YCu
although they have the same B2 structure. The results show that the core
structure and Peierls stress depend monotonically on the unstable
stacking fault energy.

Using depletion approximation theory and introducing acceptor
defects which can characterize radiation induced deep-level defects
in AlGaN/GaN heterostructures, we set up a radiation damage model of
AlGaN/GaN high electron mobility transistor (HEMT) to separately
simulate the effects of several main radiation damage mechanisms and
the complete radiation damage effect simultaneously considering the
degradation in mobility. Our calculated results, consistent with the experimental results,
indicate that thin AlGaN barrier
layer, high Al content and high doping concentration are favourable
for restraining the shifts of threshold voltage in the AlGaN/GaN
HEMT; when the acceptor concentration induced is less than
10^{14}cm^{-3}, the shifts in threshold voltage are not
obvious; only when the acceptor concentration induced is higher than
10^{16}cm^{-3}, will the shifts of threshold voltage
remarkably increase; the increase of threshold voltage, resulting
from radiation induced acceptor, mainly contributes to the
degradation in drain saturation current of the current--voltage
(I--V) characteristic, but has no effect on the transconductance
in the saturation area.

Using the Stillinger--Weber (SW) potential model, we investigate the
thermal stability of pristine silicon nanowires based on classical
molecular dynamics (MD) simulations. We explore the structural
evolutions and the Lindemann indices of silicon nanowires at
different temperatures in order to unveil atomic-level melting
behaviour of silicon nanowires. The simulation results show that
silicon nanowires with surface reconstructions have higher thermal
stability than those without surface reconstructions, and that
silicon nanowires with perpendicular dimmer rows on the two (100)
surfaces have somewhat higher thermal stability than nanowires with
parallel dimmer rows on the two (100) surfaces. Furthermore, the
melting temperature of silicon nanowires increases as their diameter
increases and reaches a saturation value close to the melting
temperature of bulk silicon. The value of the Lindemann index for
melting silicon nanowires is 0.037.

This paper reports that nanoporous AlN particles are synthesized
from solid-state metathesis reactions using AlCl_{3} and
Mg_{3}N_{2} as reactants. The samples are characterized by x-ray
diffraction (XRD), transmission electron microscopy (TEM), selected
area electron diffraction, high-resolution transmission electron
microscopy (HRTEM), ultraviolet--visible (UV--vis) absorption
spectroscopy and Raman spectroscopy. The results show that
samples with walls 10 nm in thickness and pores between 10 nm and
100 nm in diameter were produced successfully from these reactions, and
their band gap and vibration modes agree with those of AlN bulk
crystal.

CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES

This paper presents a microscopic theory to explain different Raman
modes of La_{0.5}Ca_{0.5}MnO_{3} based on the electronic
Hamiltonian of the Kondo lattice model, which adds phonon interaction
to the hybridization between the conduction electrons of the system
and the l-electrons. The spectral density is calculated by the
Green function technique of Zubarev at zero wave vector and in the low
temperature limit. It finds that there are three Raman-active modes
and the spectral densities of these modes are substantially
influenced by model parameters such as the position of l-level
(ε_{JT}), the effective electron--phonon coupling
strength (g) and the hybridization parameter (v). Finally, the
intensity changes of those peaks are investigated.

Montmorillonite is a kind of clay mineral which often causes large
deformation in soft-rock tunnel engineering and thus brings about
safety problems in practice. To deal with these engineering safety
problems, the physical and chemical properties of montmorillonite
should be studied from basic viewpoints. We study the atomic and
electronic structures of montmorillonite by using density-functional
theory within the local-density approximation (LDA). The results of
calculation show that Al--O bond lengths are longer than Si--O bond
lengths. It is found that both the valence band maximum (VBM) and
the conduction band minimum (CBM) of montmorillonite are at point
Γ, and the calculated direct band gap of montmorillonite
is 5.35~eV. We show that the chemical bonding between cations and
oxygen anions in montmorillonite is mainly ionic, accompanied as
well by a minor covalent component. It is pointed out that the VBM
and CBM of montmorillonite consist of oxygen 2p and cation s states,
respectively. Our calculated results help to understand the chemical
and physical properties of montmorillonite, and are expected to be a
guide for solving the problem of large deformation of soft-rock
tunnels.

The electronic and optical properties of the cubic zinc-blende (ZB)
structured filled tetrahedral semiconductor α-LiZnN
under pressure are investigated by using \textit{ab initio} plane
wave pseudopotential density functional theory method within the
generalized gradient approximation (GGA). The electronic band
structure and the density of state under pressure are systematically
described. The basic optical constants, including the reflection and
absorption spectra, the energy-loss function, the complex refractive
index and the dielectric function, are calculated and analysed at
different external pressures. Our results suggested that the ZB
α-LiZnN is transparent in the partially
ultra-violet to the visible light region, and it seems that the
transparency is hardly affected by the pressure.

This paper investigates the effect of Nb doping on the electronic
structure and optical properties of Sr_{2}TiO_{4} by the
first-principles calculation of plane wave ultra-soft
pseudo-potential based on density functional theory (DFT). The
calculated results reveal that due to the electron doping, the Fermi
level shifts into conduction bands(CBs) for Sr_{2}Nb_{x}Ti_{1-x}O_{4} with x=0.125 and the system shows n-type degenerate
semiconductor features. Sr_{2}TiO_{4} exhibits optical
anisotropy in its main crystal axes, and the c-axis shows the most
suitable crystal growth direction for obtaining a wide transparent
region. The optical transmittance is higher than 90% in the
visible range for Sr_{2}Nb_{0.125}Ti_{0.875}O_{4}.

The magnetism, the magnetocrystalline anisotropy and the optical
properties of the monolayer and atomic chain of 4d transition-metal Ru
are investigated by using the full-potential
linearized-augmented-plane-wave method in a generalized gradient
approximation. The magnetic moments are 1.039~μ __{B}/atom and 1.130~μ_{B}/atom for the monolayer and
atomic chain, respectively. Both systems have large
magnetocrystalline anisotropy energy (MAE). The magnetic easy axis
is normal to the monolayer and perpendicular to the chain axis in
the atomic chain. The optical properties of the two low-dimensional
Ru systems are investigated by calculating the complex optical
conductivity tensor. Both systems exhibit anisotropy in
photoconductivity, especially for the atomic chain. The physical
origins of MAE and photoconductivity are studied based on electronic
structures. It is found that the changes in crystal field caused by
different symmetry-breaking mechanisms in the two low-dimensional Ru
systems result in MAE through spin--orbit coupling, while the
anisotropy in photoconductivity mainly comes from the
crystallographic anisotropy.

The effect of interchain coupling on the formation and the stability of a biexciton is studied in poly (p-phenylene vinylene) chains in the framework of the tight-binding approach. We obtain an intrachain exciton and biexciton as well as an interchain exciton and biexciton through a double-photon excitation. It is found that a biexciton is energetically favourable to two single excitons even when there exists an interchain coupling. There is a turnover value t_{⊥C} of the interchain coupling for the formation of a biexciton, beyond which two excitons are combined into one biexciton. The binding energy of a biexciton is calculated to decrease with the increase of interchain coupling, which indicates that a biexciton is relatively stable in polymers with a weak interchain coupling. The conclusion is consistent with the experimental observations. In addition, a suggestion about how to improve the yielding efficiency or the formation of biexcitons in actual applications is given.

A simple theoretical method is introduced for studying the
interrelation between electronic and molecular structures. By
diagonalizing the 120× 120 complete energy matrices, the
relationships between zero-field splitting (ZFS) parameter D and
local distortion parameter Δθ for Cr^{3+} ions
doped, separately, in α- and β- alums are investigated.
Our results indicate that there exists an approximately linear
relationship between D and Δθ in a temperature range
4.2--297~K and the signs of D and Δθ are opposite to
each other. Moreover, in order to understand the contribution of
spin--orbit coupling coefficient ζ to ZFS parameter D, the
relation between D and ζ is also discussed.

In order to consider quantum transport under the influence of an
electron--electron (e--e) interaction in a mesoscopic conductor, the
Boltzmann equation and Poisson equation are investigated jointly.
The analytical expressions of the distribution function for the Boltzmann
equation and the self-consistent average potential concerned with e--e
interaction are obtained, and the dielectric function appearing in
the self-consistent average potential is naturally generalized
beyond the Thomas--Fermi approximation. Then we apply these results to
the tunneling junctions of a metal--insulator--semiconductor (MIS) in
which the electrons are accumulated near the interface of the
semiconductor, and we find that the e--e interaction plays an
important role in the transport procedure of this system. The
electronic density, electric current as well as screening Coulombic
potential in this case are studied, and we reveal the time and
position dependence of these physical quantities explicitly affected by the e--e
interaction.

This paper shows that a substantial amount of dissipationless
spin-Hall current contribution may exist in the extrinsic spin-Hall
effect, which originates from the spin-orbit coupling induced by
the applied external electric field itself that drives the extrinsic
spin-Hall effect in a nonmagnetic semiconductor (or metal). By
assuming that the impurity density is in a moderate range such that
the total scattering potential due to all randomly distributed
impurities is a smooth function of the space coordinate, it is shown
that this dissipationless contribution shall be of the same orders
of magnitude as the usual extrinsic contribution from spin-orbit
dependent impurity scatterings (or may even be larger than the
latter one). The theoretical results obtained are in good agreement
with recent relevant experimental results.

This paper investigates the infrared absorption spectra of oxygen-related complexes in silicon crystals irradiated with
electron (1.5~MeV) at 360~K. Two groups of samples with low [O_{i}]=6.9× 10^{17}~cm^{-3} and high [ O_{i}]=1.06× 10^{18}~cm^{-3} were used. We found that the
concentration of the VO pairs have different behaviour to the
annealing temperature in different concentration of oxygen specimen,
it is hardly changed in the higher concentration of oxygen specimen. It
was also found that the concentration of VO_{2} in lower concentration
of oxygen specimen gets to maximum at 450~℃ and then
dissapears at 500~℃, accompanied with the appearing of
VO_{3}. For both kinds of specimens, the concentration of VO_{3}
reachs to maximum at 550~℃ and does not disappear
completely at 600~℃.

A first-principles method based on density functional theory (DFT),
a generalized gradient approximation (GGA), and a projector-augmented
wave (PAW) are used to study the structual and band properties of
wurtzite Zn_{1-x}Cd_{x}O and Zn_{1-x}Mg_{x}O (0\leqq
x\leqq 1) ternary alloys. By taking into account all of the
possible structures, the band gaps of Zn_{1-x}Cd_{x}O and
Zn_{1-x}Mg_{x}O alloys are corrected and compared with
experimental data.

This paper finds that the two-dimensional electron gas density in
high Al-content AlGaN/GaN heterostructures exhibits an obvious
time-dependent degradation after the epitaxial growth. The
degradation mechanism was investigated in depth using Hall effect
measurements, high resolution x-ray diffraction, scanning electron
microscopy, x-ray photoelectron spectroscopy and energy dispersive
x-ray spectroscopy. The results reveal that the formation of surface
oxide is the main reason for the degradation, and the surface
oxidation always occurs within the surface hexagonal defects for
high Al-content AlGaN/GaN heterostructures.

Fabrication of ambipolar organic field-effect transistors (OFETs) is
essential for the achievement of an organic complementary logic
circuit. Ambipolar transports in OFETs with heterojunction
structures are realized. We select pentacene as a P-type material and
N,N'-bis(4-trifluoromethylben-zyl)perylene-3,4,9,10-tetracarboxylic
diimide (PTCDI-TFB) as a n-type material in the active layer of the
OFETs. The field-effect transistor shows highly air-stable ambipolar
characteristics with a field-effect hole mobility of
0.18~cm^{2}/(V.s) and field-effect electron mobility of
0.031~cm^{2}/(V.s). Furthermore the mobility only slightly
decreases after being exposed to air and remains stable even for
exposure to air for more than 60 days. The high electron affinity of
PTCDI-TFB and the octadecyltrichlorosilane (OTS) self-assembly
monolayer between the SiO_{2} gate dielectric and the organic
active layer result in the observed air-stable characteristics of
OFETs with high mobility. The results demonstrate that using the OTS
as a modified gate insulator layer and using high electron affinity
semiconductor materials are two effective methods to fabricate OFETs
with air-stable characteristics and high mobility.

The atomic and electronic structures of a graphene monolayer on a Ru(0001)
surface under compressive strain are investigated by using
first-principles calculations. Three models of graphene monolayers
with different carbon periodicities due to the lattice mismatch are proposed in the presence and the absence of the Ru(0001) substrate separately. Considering the strain induced by the lattice mismatch, we optimize the atomic structures and investigate the electronic properties of the graphene. Our calculation results show that the graphene layers turn into periodic corrugations and there exist strong chemical bonds in the interface between the graphene N×N superlattice and the substrate. The strain does not induce significant changes in electronic structure. Furthermore, the results calculated in the local density approximation (LDA) are compared with those obtained in the generalized gradient approximation (GGA), showing that the LDA results are more reasonable than the GGA results when only two substrate layers are used in calculation.

This paper discusses the effect of N_{2} plasma treatment before
dielectric deposition on the electrical performance of
a Al_{2}O_{3}/AlGaN/GaN metal-insulator-semiconductor high
electron mobility transistor (MISHEMT), with Al_{2}O_{3}
deposited by atomic layer deposition. The results indicated that the gate
leakage was decreased two orders of magnitude after the
Al_{2}O_{3}/AlGaN interface was pretreated by N_{2} plasma.
Furthermore, effects of N_{2} plasma pretreatment on the
electrical properties of the AlGaN/Al_{2}O_{1-x} interface were
investigated by x-ray photoelectron spectroscopy measurements and
the interface quality between Al_{2}O_{3} and AlGaN film was
improved.

This paper reports that multi-recessed gate 4H-SiC MESFETs
(metal semiconductor filed effect transistors) with a gate periphery
of 5-mm are fabricated and characterized. The multi-recessed region
under the gate terminal is applied to improve the gate--drain
breakdown voltage and to alleviate the trapping induced
instabilities by moving the current path away from the surface of
the device. The experimental results demonstrate that microwave
output power density, power gain and power-added efficiency for
multi-finger 5-mm gate periphery SiC MESFETs with multi-recessed
gate structure are about 29%, 1.1dB and 7% higher than those
of conventional devices fabricated in this work using the same
process.

Tungsten oxide nanowires of diameters ranging from 7 to 200~nm are
prepared on a tungsten rod substrate by using the chemical vapour
deposition (CVD) method with vapour--solid (VS) mechanism. Tin
powders are used to control oxygen concentration in the furnace,
thereby assisting the growth of the tungsten oxide nanowires. The
grown tungsten oxide nanowires are determined to be of crystalline
W_{18}O_{49}. I--V curves are measured by an \textit{in
situ} transmission electron microscope (TEM) to investigate the
electrical properties of the nanowires. All of the I--V curves
observed are symmetric, which reveals that the tungsten oxide
nanowires are semiconducting. Quantitative analyses of the
experimental I--V curves by using a metal--semiconductor--metal
(MSM) model give some intrinsic parameters of the tungsten oxide
nanowires, such as the carrier concentration, the carrier mobility
and the conductivity.

The martensitic transformation in Co_{37}Ni_{34}Al_{29} ribbon
is characterized in detail by means of in-situ thermostatic x-ray
diffraction and magnetic measurements. The results show a structural
transition from the body-centred cubic to martensite with a
tetragonal structure during cooling. Comparison between the
results of the diffraction intensity with the magnetic
susceptibility measurements indicates that the martensitic
transformation takes place in several different steps during cooling
from 273 to 163~K. During heating from 313 to 873~K, the peak width
becomes very wide and the intensity turns very low. The
γ-phase (face-centred cubic structure) emerges and increases
gradually with temperature increasing from 873 to 1073~K.

The effect of cobalt-doping on the magnetic, transport and magnetoresistance characteristics of La_{1-x}Sr_{x}MnO_{3} was investigated. The results show that the magnetoelectric property of
rare-earth doped manganites is greatly affected by substitution of Co for Mn sites. The Curie temperature as well as the magnetic moment decreases with the increase of doping concentration, and the samples exhibit obvious characteristics of the spin glass state. Moreover, the magnetoresistance is evidently modulated by doping concentration,
and the relevant temperature dependence is also suppressed. In addition, low-temperature magnetoresistance is significantly
promoted as doping concentration increases, which renders a value of approximately 50% in the temperature range of 5--200~K and varies within 12.5%. It can be attributed to the effect of spin scattering, induced by cobalt doping, on the itinerant electrons of Mn ions, thus introducing a spin-disorder region into the ferromagnetic region of double-exchange interaction between neighbouring Mn^{3+} and Mn ^{3+} ions.

This paper reports that a chemical method is employed to
synthesize Co and Al co-doped ZnO, namely, Zn_{0.99-x}Co_{0.01}Al_{x}O dilution semiconductors with the nominal composition of x=0, 0.005 and 0.02. Structural, magnetic and
optical properties of the produced samples are studied. The results
indicate that samples sintered in air under the temperatures of
500~℃ show a single wurtzite ZnO structure and the
ferromagnetism decreases with the increase of Al. Photoluminescence
spectra of different Al-doped samples indicate that increasing Al
concentration in Zn_{0.99-x}Co_{0.01}Al_{x}O results in a
decrease of Zn_{i}, which resembles the trend of the
ferromagnetic property of the corresponding samples. Therefore, it
is deduced that the ferromagnetism observed in the studied samples
originates from the interstitial defect of zinc (Zn_{i} )
in the lattice of Co-doped ZnO.

This paper compares the properties of silicon oxide and nitride as
host matrices for Er ions. Erbium-doped silicon nitride films were
deposited by a plasma-enhanced chemical-vapour deposition system.
After deposition, the films were implanted with Er^{3+} at
different doses. Er-doped thermal grown silicon oxide films were
prepared at the same time as references. Photoluminescence features
of Er^{3+} were inspected systematically. It is found that silicon
nitride films are suitable for high concentration doping and the
thermal quenching effect is not severe. However, a very high annealing
temperature up to 1200~℃ is needed to optically activate
Er^{3+}, which may be the main obstacle to impede the application
of Er-doped silicon nitride.

This paper considers the frequency-quadrupling three-cavity
gyroklystrons with successive frequency-doubling in each cavity. The
cavities of 225~GHz frequency-quadrupling gyroklystron are designed
with the scattering matrices method and the possible operating mode
are discussed. With the point-gap theory, the starting currents of
the possible operating modes and the potential parasitic modes in the
output cavity are calculated. The optimal operating mode is proposed
under consideration of the mode competition and the power capacity
of the cavity.

By taking into account structural transition zones near the lateral
and thickness direction edges, this paper uses a modified transverse
Ising model to study dielectric properties of a finite size
ferroelectric thin film in the framework of the mean-field
approximation. The results indicate that the influence of the
lateral size on the dielectric susceptibility cannot be neglected
and lateral structural transition zones could be a crucial factor
that improves the mean susceptibility of the fixed size film.

This paper reports that two kinds of polymers with high infrared
transparency and good mechanical and physical properties have been
prepared. An internal standard method is used to evaluate the infrared
transparency of the binders. The physical and mechanical properties of the
binders are measured according to corresponding standards. The
results show the absorbance of polymer A in 8--14~μ m range is
26% that of the ethylene-vinyl acetate copolymer (EVA), and polymer B
is 9% that of the EVA correspondingly. The film of polymer A shows
good flexibility of above 1~mm, a hardness of grade 1, and adhesion of
grade 2. The film of polymer B shows good flexibility of above 1~mm,
a hardness of grade 1, and adhesion of grade 1.

Hamamatsu SHR74000 is a newly designed full three-dimensional (3D) whole body
positron emission tomography (PET)
scanner with small crystal size and large field of view (FOV). With
the improvement of sensitivity, the scatter events increase
significantly at the same time, especially for large objects.
Monte Carlo simulations help us to understand the scatter phenomena and
provide good references for scatter correction. In this paper, we
introduce an effective scatter correction method based on single
scatter simulation for the new PET scanner, which accounts for the
full 3D scatter correction. With the results from Monte Carlo
simulations, we implement a new scale method with special
concentration on scatter events from outside the axial FOV and
multiple scatter events. The effects of scatter correction are
investigated and evaluated by phantom experiments; the results
show good improvements in quantitative accuracy and
contrast of the images, even for large objects.

Using a neutral N_{2} beam as target, this paper studies the
dissociation of N_{2}^{+} in intense femtosecond laser fields
(45~fs, ～ 1× 10^{16}~W/cm^{2}) at the laser wavelength of
800 nm based on the time-of-flight mass spectra of N^{+}
fragment ions. The angular distributions of N^{+} and the laser
power dependence of N^{+} yielded from different dissociation
pathways show that the dissociation mechanisms mainly proceed
through the couplings between the metastable states (A, B and
C) and the upper excited states of N_{2}^{+}. A coupling model
of light-dressed potential energy curves of N_{2}^{+} is used to
interpret the kinetic energy release of N^{+}.

8000 CROSSDISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY

Although the nonlinear interactions between a single short gravity
wave and a long wave can be solved analytically, the solution is
less tractable in more general cases involving multiple short waves.
In this work we present a numerical method of studying nonlinear
interactions between a long wave and multiple short harmonic waves
in infinitely deep water. Specifically, this method is applied to
the calculation of the temporal and spatial evolutions of the
surface elevations in which a given long wave interacts with several
short harmonic waves. Another important application of our method is
to quantitatively analyse the nonlinear interactions between an
arbitrary short wave train and another short wave train. From
simulation results, we obtain that the mechanism for the nonlinear
interactions between one short wave train and another short wave
train (expressed as wave train 2) leads to the energy focusing of
the other short wave train (expressed as wave train 3). This
mechanism occurs on wave components with a narrow frequency
bandwidth, whose frequencies are near that of wave train 3.

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