4,784 research outputs found
Different contributions to space weather and space climate from different big solar active regions
The purpose of this paper is to show that large active regions (ARs) with
different magnetic configurations have different contributions to short-term
and long-term variations of the Sun. As a case study, the complex -type
AR 12673 and the simple -type AR 12674 are investigated in detail. Since
the axial dipole moment at cycle minimum determines the amplitude of the
subsequent cycle and space climate, we have assimilated the individual observed
magnetic configurations of these two ARs into a surface flux transport model to
compare their contributions to the axial dipole moment . We find that AR
12673 has a significant effect on at the end of the cycle, making it weaker
because of the abnormal and complicated magnetic polarities. An initial
strongly positive ends up with a strongly negative value. The flare-poor AR
12674 has a greater contribution to the long-term axial dipole moment than the
flare-rich AR 12673. We then carry out a statistical analysis of ARs larger
than 800 Hem from 1976 to 2017. We use the flare index FI and define an
axial dipole moment index DI to quantify the effects of each AR on space
weather and space climate, respectively. Whereas the FI has a strong dependence
on the magnetic configuration, the DI shows no such dependence. The DI is
mainly determined by the latitudinal location and the latitudinal separation of
the positive and negative magnetic fluxes of the ARs. Simple ARs have the same
possibility as complex ARs to produce big DI values affecting space climate.Comment: 18 pages, 8 figures, Accepted for publication in the Astrophysical
Journa
Differences in neuromuscular junctions between intrinsic muscles of the forepaw and biceps muscles in rats
Motor endplates of the interossei muscles become destabilized, whereas those of the biceps muscles remain stable in a rat model of obstetric brachial plexus palsy. However, it is unclear whether the morphology of the motor endplates of the interossei muscles is different from that of the biceps muscles in normal rat. We hypothesized that the motor endplates in the interossei muscles have specific characteristics different from those in the biceps muscles. The motor endplates were labeled with α-bungarotoxin and synaptophysin. The cross-sectional areas of the muscle fibers, the morphologies of the motor endplates, and the absolute and normalized areas (corrected by muscle fiber diameter) of the motor endplates of the interossei muscles and the biceps muscles were compared in rats at 1, 3, and 5 weeks after birth. The cross-sectional area of the interossei muscles and biceps muscle fibers were found to have increased gradually at 1, 3, and 5 weeks, but that of the biceps muscles was larger than that of the interossei muscles. The motor endplates of the interossei muscles and the biceps muscles gradually develop from crescent to pretzel shape after birth, and those of the interossei muscles have a smaller area. At 1, 3, and 5 weeks postnatally, the area of postnatal normalized motor endplates of the interossei muscles was much smaller than that of the biceps muscles. A better understanding of the morphological differences of the motor endplates between the interossei muscles and the biceps muscles may help to understand their physiological and pathological changes
Study of B^{0}_{s} \rightarrow \ TT(a_{2}(1320),K^{*}_{2}(1430),f_{2}(1270),f^{'}_{2}(1525)) in the perturbative QCD approach
In this work, we calculate the two-body decays B^{0}_{s} \rightarrow \ TT ( T
denotes tensor mesons, a_{2}(1320), K^{*}_{2}(1430), f_{2}(1270),
f^{'}_{2}(1525)) in the perturbative QCD approach. The predictions of branching
rations, polarization fractions, and direct CP violations are given in detail.
We find that: (a) For the pure annihilation decay, the longitudinal
polarization is around 90.0\%, and the transverse polarizations are relatively
small; (b) The direct CP asymmetry is proportional to the interference between
the tree and penguin contributions. The direct CP asymmetry for most decays are
small in this paper; (c) Here are only six kinds of Feynman diagrams for
B^{0}_{s} \rightarrow \ TT, because the tensor mesons cannot be produced
through the (V \pm A) currents or (S \pm P) density, the factorizable emission
diagrams are prohibited, the nonfactorizable and annihilation contributions are
important in these decay modes. The branching ratios of our calculation for
B^{0}_{s} \rightarrow \ TT are at the order of 10^{-6} and 10^{-7}, which can
be tested in the LHC-b and Belle II experiments; (d) Mixing exists for the
f_{2}(1270)and f^{'}_{2}(1525), just as the \eta and \eta^{'} mixing, the
branching ratios about the mixing angle \theta are given in this work. But it
is different from f_{1}(1285)-f_{1}(1420), the mixing angle is very small, so
the decay branching ratio only has little change.Comment: we have corrected some printing error
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