36,712 research outputs found
Genetic diversity and population structure of Chinese honeybees (Apis cerana) under microsatellite markers
Using 21 microsatellite markers and PCR method, the polymorphisms of 20 Apis cerana honeybee populations across China was investigated and the genetic structure and diversity of the populations were explored. The results showed that 507 alleles (mean 24.14 per locus, ranging from 13 to 45) were observed in 842 honeybees. Wuding bee had the highest level of heterozygosity (0.695), and the lowest estimate was 0.207 for Changbai bee. The global heterozygote deficit across all populations (Fit) amounted to 0.776. About 42.3% of the total genetic variability originated from differences between breeds, with all loci contributing significantly to the differentiation. An unrooted consensus tree using the Neighbour-Joining method and pair-wise distances showed that 6 populations from Eastern China clustered together. The structure analysis indicated that the 6 populations were separated first. These findings demonstrated that the 6 honeybee populations had close genetic relationships.Key words: Apis cerana, microsatellite, polymorphism, genetic structure
Analysis of pion elliptic flows and HBT interferometry in a granular quark-gluon plasma droplet model
In many simulations of high-energy heavy-ion collisions on an event-by-event
analysis, it is known that the initial energy density distribution in the
transverse plane is highly fluctuating. Subsequent longitudinal expansion will
lead to many longitudinal tubes of quark-gluon plasma which have tendencies to
break up into many spherical droplets because of sausage instabilities. We are
therefore motivated to use a model of quark-gluon plasma granular droplets that
evolve hydrodynamically to investigate pion elliptic flows and
Hanbury-Brown-Twiss interferometry. We find that the data of pion transverse
momentum spectra, elliptic flows, and HBT radii in \sqrt{s_{NN}}=200 GeV Au +
Au collisions at RHIC can be described well by an expanding source of granular
droplets with an anisotropic velocity distribution.Comment: 9 pages, 6 figures, in Late
Scanning Tunneling Spectroscopy and Vortex Imaging in the Iron-Pnictide Superconductor BaFeCoAs
We present an atomic resolution scanning tunneling spectroscopy study of
superconducting BaFeCoAs single crystals in magnetic fields
up to . At zero field, a single gap with coherence peaks at
is observed in the density of states. At and , we image a disordered vortex lattice, consistent
with isotropic, single flux quantum vortices. Vortex locations are uncorrelated
with strong scattering surface impurities, demonstrating bulk pinning. The
vortex-induced sub-gap density of states fits an exponential decay from the
vortex center, from which we extract a coherence length , corresponding to an upper critical field .Comment: 4 pages, 4 figure
Collective excitations in a fermion-fermion mixture with different Fermi surfaces
In this paper, collective excitations in a homogeneous fermion-fermion
mixture with different Fermi surfaces are studied. In the Fermi liquid phase,
the zero-sound velocity is found to be larger than the largest Fermi velocity.
With attractive interactions, the superfluid phase appears below a critical
temperature, and the phase mode is the low-energy collective excitation. The
velocity of the phase mode is proportional to the geometric mean of the two
Fermi velocities. The difference between the two velocities may serve as a tool
to detect the superfluid phase.Comment: 4 pages. To be published in Phys. Rev.
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