294,340 research outputs found
Using Microsatellites to Assess Genetic Variation in a Selective Breeding Program of Chinese Bay Scallop (Argopecten irradians irradians)
This study aimed to improve our understanding of the genetics of the Chinese bay scallop (Argopecten irradians irradians), one of the most important maricultured shellfish in China. Ten polymorphic microsatellite loci were examined to assess the allelic diversity, heterozygosity, and genetic variation between two domesticated populations selected for fast growth in breeding programs, and their base population. Forty-one alleles were found throughout the loci and the mean number of alleles per locus ranged 3.30-3.50. The average heterozygosity ranged 0.38-0.45, whereas the polyamorphic information content ranged 0.1504-0.7518. Genetic differences between the three populations were detected based on the number of alleles per locus, effective number of alleles, Shannon index, inbreeding coefficient (Fis), p values, genetic distance, and pairwise Fst values. There was no significant loss of genetic variability in the breeding program but changes in gene frequencies were detectable over the populations, implying that thea loci were saffected by the pressures of selective culture
Precise Algorithm to Generate Random Sequential Addition of Hard Hyperspheres at Saturation
Random sequential addition (RSA) time-dependent packing process, in which
congruent hard hyperspheres are randomly and sequentially placed into a system
without interparticle overlap, is a useful packing model to study disorder in
high dimensions. Of particular interest is the infinite-time {\it saturation}
limit in which the available space for another sphere tends to zero. However,
the associated saturation density has been determined in all previous
investigations by extrapolating the density results for near-saturation
configurations to the saturation limit, which necessarily introduces numerical
uncertainties. We have refined an algorithm devised by us [S. Torquato, O.
Uche, and F.~H. Stillinger, Phys. Rev. E {\bf 74}, 061308 (2006)] to generate
RSA packings of identical hyperspheres. The improved algorithm produce such
packings that are guaranteed to contain no available space using finite
computational time with heretofore unattained precision and across the widest
range of dimensions (). We have also calculated the packing and
covering densities, pair correlation function and structure factor
of the saturated RSA configurations. As the space dimension increases,
we find that pair correlations markedly diminish, consistent with a recently
proposed "decorrelation" principle, and the degree of "hyperuniformity"
(suppression of infinite-wavelength density fluctuations) increases. We have
also calculated the void exclusion probability in order to compute the
so-called quantizer error of the RSA packings, which is related to the second
moment of inertia of the average Voronoi cell. Our algorithm is easily
generalizable to generate saturated RSA packings of nonspherical particles
On cost-effective communication network designing
How to efficiently design a communication network is a paramount task for
network designing and engineering. It is, however, not a single objective
optimization process as perceived by most previous researches, i.e., to
maximize its transmission capacity, but a multi-objective optimization process,
with lowering its cost to be another important objective. These two objectives
are often contradictive in that optimizing one objective may deteriorate the
other. After a deep investigation of the impact that network topology, node
capability scheme and routing algorithm as well as their interplays have on the
two objectives, this letter presents a systematic approach to achieve a
cost-effective design by carefully choosing the three designing aspects. Only
when routing algorithm and node capability scheme are elegantly chosen can
BA-like scale-free networks have the potential of achieving good tradeoff
between the two objectives. Random networks, on the other hand, have the
built-in character for a cost-effective design, especially when other aspects
cannot be determined beforehand.Comment: 6 pages, 4 figure
Scaling of nuclear modification factors for hadrons and light nuclei
The number of constituent quarks (NCQ-) scaling of hadrons and the number of
constituent nucleons (NCN-) scaling of light nuclei are proposed for nuclear
modification factors () of hadrons and light nuclei, respectively,
according to the experimental investigations in relativistic heavy-ion
collisions. Based on coalescence mechanism the scalings are performed for pions
and protons in quark level, and light nuclei and He for
nucleonic level, respectively, formed in Au + Au and Pb + Pb collisions and
nice scaling behaviour emerges. NCQ or NCN scaling law of can be
respectively taken as a probe for quark or nucleon coalescence mechanism for
the formation of hadron or light nuclei in relativistic heavy-ion collisions.Comment: 6 pages, 6 figure
Hot spin spots in the laser-induced demagnetization
Laser-induced femtosecond magnetism or femtomagnetism simultaneously relies
on two distinctive contributions: (a) the optical dipole interaction (ODI)
between a laser field and a magnetic system and (b) the spin expectation value
change (SEC) between two transition states. Surprisingly, up to now, no study
has taken both contributions into account simultaneously. Here we do so by
introducing a new concept of the optical spin generator, a product of SEC and
ODI between transition states. In ferromagnetic nickel, our first-principles
calculation demonstrates that the larger the value of optical spin generator
is, the larger the dynamic spin moment change is. This simple generator
directly links the time-dependent spin moment change {\Delta}Mk z (t) at every
crystal- momentum k point to its intrinsic electronic structure and magnetic
properties. Those hot spin spots are a direct manifestation of the optical spin
generator, and should be the focus of future research.Comment: 10 pages, 2 figures, [email protected]
Analytic continuation of single-particle resonance energy and wave function in relativistic mean field theory
Single-particle resonant states in spherical nuclei are studied by an
analytic continuation in the coupling constant (ACCC) method within the
framework of the self-consistent relativistic mean field (RMF) theory. Taking
the neutron resonant state in Ca as an example, we
examine the analyticity of the eigenvalue and eigenfunction for the Dirac
equation with respect to the coupling constant by means of a \pade
approximant of the second kind. The RMF-ACCC approach is then applied to
Zr and, for the first time, this approach is employed to investigate
both the energies, widths and wave functions for resonant states close
to the continuum threshold. Predictions are also compared with corresponding
results obtained from the scattering phase shift method.Comment: 19 pages, 9 figure
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