10,362 research outputs found
The superheated Melting of Grain Boundary
Based on a model of the melting of Grain Boundary (GB), we discuss the
possibility of the existence of superheated GB state. A Molecular Dynamics
simulation presented here shows that the superheated GB state can realized in
the high symmetric tilt GB. Whether the sizes of liquid nuclei exceed a
critical size determined the superheating grain boundary melting or not. Our
results also indicate that the increase of melting point due to pressure is
smaller than the superheating due to nucleation mechanism.Comment: Accepted by PRB, 7 pages and 5 figure
The Three-body Force and the Tetraquark Interpretation of Light Scalar Mesons
We study the possible tetraquark interpretation of light scalar meson states
, , , within the framework of the
non-relativistic potential model. The wave functions of tetraquark states are
obtained in a space spanned by multiple Gaussian functions. We find that the
mass spectra of the light scalar mesons can be well accommodated in the
tetraquark picture if we introduce a three-body quark interaction in the quark
model. Using the obtained multiple Gaussian wave functions, the decay constants
of tetraquarks are also calculated within the ``fall apart'' mechanism
The Tensor Current Divergence Equation in U(1) Gauge Theories is Free of Anomalies
The possible anomaly of the tensor current divergence equation in U(1) gauge
theories is calculated by means of perturbative method. It is found that the
tensor current divergence equation is free of anomalies.Comment: Revtex4, 7 pages, 2 figure
The X-ray emission lines in GRB afterglows: the evidence for the two-component jet model
Recently, X-ray emission lines have been observed in X-ray afterglows of
several -ray bursts. It is a major breakthrough for understanding the
nature of the progenitors. It is proposed that the X-ray emission lines can be
well explained by the Geometry-Dominated models, but in these models the
illuminating angle is much larger than that of the collimated jet of the
-ray bursts(GRBs). For GRB 011211, we obtain the illuminating angle is
about , while the angle of GRB jet is only ,
so we propose that the outflow of the GRBs with emission lines should have two
distinct components. The wide component illuminates the reprocessing material,
and produces the emission lines, while the narrow one produces the -ray
bursts. The observations show that the energy for producing the emission lines
is higher than that of the GRBs. In this case, when the wide component
dominates the afterglows, a bump will appear in the GRBs afterglows. For GRB
011211, the emergence time of the bump is less than 0.05 days after the GRB, it
is obviously too early for the observation to catch it. With the presence of
the X-ray emission lines there should also be a bright emission component
between the UV and the soft X-rays. These features can be tested by the
satellite in the near future.Comment: 10 pags, 1 figure, ChJAA in pres
The effects of reciprocal cross on inheritance of DNA methylation in cotton (Gossypium hirsutum)
DNA methylation plays an important role for regulation of gene expression. To study the inheritance of DNA methylation, we selected two F1 plant population by reciprocal cross with two cotton lines Zongcaixuan No.1 and HY428, and analyzed the variations of DNA methylation levels and patterns in F1 generations by methylation sensitive amplified fragment length polymorphism (MSAP) technique with 54 primer combinations. The results show that most cytosine methylated patterns are conservatively inherited from parents. The numbers of variant sites are less in F1 generation. According to the number of sites individually inherited from female and male parents, the different choice of female and male parents made a big distinction between the sites inherited from female parent and the sites inherited from the male parent. For reciprocal cross F113 and F132, the number for sites of cytosine methylation patterns inherited from the female parent are far more than that from the male parent, which may be closely related to cytoplasmic inheritance.Key words: Methylation sensitive amplified fragment length polymorphism (MSAP), DNA methylation, cytoplasmic inheritance, reciprocal cross, cotton
Polarization evolution accompanying the very early sharp decline of GRB X-ray afterglows
In the synchrotron radiation model, the polarization property depends on both
the configuration of the magnetic field and the geometry of the visible
emitting region. Some peculiar behaviors in the X-ray afterglows of {\it Swift}
gamma-ray bursts (GRBs), such as energetic flares and the plateau followed by a
sharp drop, might by highly linearly-polarized because the outflows powering
these behaviors may be Poynting-flux dominated. Furthermore, the broken-down of
the symmetry of the visible emitting region may be hiding in current X-ray data
and will give rise to interesting polarization signatures. In this work we
focus on the polarization accompanying the very early sharp decline of GRB
X-ray afterglows. We show that strong polarization evolution is possible in
both the high latitude emission model and the dying central engine model which
are used to interpret this sharp X-ray decline. It is thus not easy to
efficiently probe the physical origin of the very early X-ray sharp decline
with future polarimetry. Strong polarization evolution is also possible in the
decline phase of X-ray flares and in the shallow decline phase of X-ray light
curves characterized by chromatic X-ray VS. Optical breaks. An {\it XRT}-like
detector but with polarization capability on board a {\em Swift}-like satellite
would be suitable to test our predictions.Comment: 9 pages including 4 figures. Accepted for publication in MNRAS, typos
correcte
Design and durability analysis of marine concrete
Marine engineering is an important way for a country to go deep blue. In the marine environment, there are many factors that affect the durability of concrete, among which the most harmful one is chloride ion erosion. In order to improve the ability to resist chloride ion permeation, this paper designs, compares and selects the appropriate water cement ratio of marine concrete, with the use of new anticorrosive technologies such as epoxy coating and silane impregnation. The design service life and the chloride ion diffusion coefficient prediction are analysed by establishing models, and this paper verifies whether the engineering design meets the service life requirement
High Temperature Macroscopic Entanglement
In this paper I intend to show that macroscopic entanglement is possible at
high temperatures. I analyze multipartite entanglement produced by the
pairing mechanism which features strongly in the fermionic lattice models of
high superconductivity. This problem is shown to be equivalent to
calculating multipartite entanglement in totally symmetric states of qubits. I
demonstrate that we can conclusively calculate the relative entropy of
entanglement within any subset of qubits in an overall symmetric state. Three
main results then follow. First, I show that the condition for
superconductivity, namely the existence of the off diagonal long range order
(ODLRO), is not dependent on two-site entanglement, but on just classical
correlations as the sites become more and more distant. Secondly, the
entanglement that does survive in the thermodynamical limit is the entanglement
of the total lattice and, at half filling, it scales with the log of the number
of sites. It is this entanglement that will exist at temperatures below the
superconducting critical temperature, which can currently be as high as 160
Kelvin. Thirdly, I prove that a complete mixture of symmetric states does not
contain any entanglement in the macroscopic limit. On the other hand, the same
mixture of symmetric states possesses the same two qubit entanglement features
as the pure states involved, in the sense that the mixing does not destroy
entanglement for finite number of qubits, albeit it does decrease it. Maximal
mixing of symmetric states also does not destroy ODLRO and classical
correlations. I discuss various other inequalities between different
entanglements as well as generalizations to the subsystems of any
dimensionality (i.e. higher than spin half).Comment: 14 pages, no figure
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