<正>The discovery of gravitational waves(GWs)by the LIGO collaboration 1 in 2016 has provided a direct test on the prediction made by Albert Einstein a century ago based on his general theory of ...relativity 2.It has caused a significant influence worldwide on the basic research in science.
We investigate the particle production from thermal gravitational annihilation in the very early universe, which is an important contribution for particles that might not be in thermal equilibrium ...or/and might only have gravitational interaction, such as dark matter (DM). For particles with spin 0,1/2 and 1 we calculate the relevant cross sections through gravitational annihilation and give the analytic formulas with full mass-dependent terms. We find that DM with mass between TeV and 1016 GeV could have the relic abundance that fits the observation, with small dependence on its spin. We also discuss the effects of gravitational annihilation from inflatons. Interestingly, contributions from inflatons could be dominant and have the same power dependence on Hubble parameter of inflation as that from vacuum fluctuation. Also, fermion production from inflaton, in comparison to boson, is suppressed by its mass due to helicity selection.
In this study, we investigate a scenario that dark matter (DM) has only gravitational interaction. In the framework of effective field theory of gravity, we find that DM is still stable at tree level ...even if there is no symmetry to protect its longevity, but could decay into standard model particles due to gravitational loop corrections. The radiative corrections can lead to both higher- and lower-dimensional effective operators. We also first explore how DM can be produced in the early universe. Through gravitational interaction at high temperature, DM is then found to have mass around TeV≲mX≲1011 GeV to get the right relic abundance. When DM decays, it mostly decays into gravitons, which could be tested by current and future CMB experiments. We also estimate the resulting fluxes for cosmic rays, gamma-ray and neutrino.
Constitutional dynamic networks (CDNs) attract interest as signal-triggered reconfigurable systems mimicking natural networks. The application of CDNs to control material properties is, however, a ...major challenge. Here we report on the design of a CDN consisting of four toehold-modified constituents, two of which act as bidentate units for chain-elongating, while the other two form a tetradentate structure acting as a crosslinking unit. Their hybridization yields a hydrogel of medium stiffness controlled by the balance between bidentate and tetradentate units. Stabilization of the tetradentate constituent by an auxiliary effector up-regulates the crosslinking unit, yielding a high-stiffness hydrogel. Conversely, stabilization of one of the bidentate constituents by an orthogonal effector enriches the chain-elongation units leading to a low-stiffness hydrogel. Using appropriate counter effectors, the hydrogels are reversibly switched across low-, medium- and high-stiffness states. The hydrogels are used to develop self-healing and controlled drug-release matrices and functional materials for operating biocatalytic cascades.
A hyperunified field theory is built in detail based on the postulates of gauge invariance and coordinate independence along with the conformal scaling symmetry. All elementary particles are merged ...into a single hyper-spinor field and all basic forces are unified into a fundamental interaction governed by the hyper-spin gauge symmetry SP(1,
D
h
-
1
). The dimension
D
h
of hyper-spacetime is conjectured to have a physical origin in correlation with the hyper-spin charge of elementary particles. The hyper-gravifield fiber bundle structure of biframe hyper-spacetime appears naturally with the globally flat Minkowski hyper-spacetime as a base spacetime and the locally flat hyper-gravifield spacetime as a fiber that is viewed as a dynamically emerged hyper-spacetime characterized by a non-commutative geometry. The gravitational origin of gauge symmetry is revealed with the hyper-gravifield that plays an essential role as a Goldstone-like field. The gauge–gravity and gravity–geometry correspondences bring about the gravitational gauge–geometry duality. The basic properties of hyperunified field theory and the issue on the fundamental scale are analyzed within the framework of quantum field theory, which allows us to describe the laws of nature in deriving the gauge gravitational equation with the conserved current and the geometric gravitational equations of Einstein-like type and beyond.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Many in vitro studies have shown that tea catechins had vevarious health beneficial effects. However, inconsistent results between in vitro and in vivo studies or between laboratory tests and ...epidemical studies are observed. Low bioavailability of tea catechins was an important factor leading to these inconsistencies. Research advances in bioavailability studies involving absorption and metabolic biotransformation of tea catechins were reviewed in the present paper. Related techniques for improving their bioavailability such as nanostructure-based drug delivery system, molecular modification, and co-administration of catechins with other bioactives were also discussed.
Carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) at different mix ratios were dispersed by ultrasonication into an epoxy matrix and the effects of CNT:GNP ratios on the mechanical and ...electrical properties of the hybrid composites were investigated. The combination of CNT and GNP in a ratio 8:2 was observed to synergistically increase flexural properties and to reduce the electrical percolation threshold for the epoxy composites, indicating easier formation of a conductive network due to the improved state of CNT dispersion in the presence of GNPs. The state of dispersion was evaluated at different length scales by using optical microscopy, UV-Vis spectroscopy, rheological measurements, scanning electron microscopy, transmission electron microscopy and sedimentation tests. The Fourier transform infrared spectra for CNT and GNP indicate that the GNPs contain oxygen moieties responsible for better interactions with the epoxy matrix.
This paper dealt with the infinite controllability of delayed evolution inclusions with $ \alpha $-order fractional derivatives in Fr$ \acute{e} $chet spaces, where $ \alpha\in (1, 2) $. The ...controllability conclusion was acquired without any compactness for the nonlinear term, the cosine family, and the sine family. The investigation was based on a nonlinear alternative and the cosine family theory. An application of our findings was provided.
Treating the gravitational force on the same footing as the electroweak and strong forces, we present a quantum field theory of gravity based on spin and scaling gauge symmetries. A biframe spacetime ...is initiated to describe such a quantum gravity theory. The locally flat gravifield spacetime spanned by the gravifield is associated with a noncommutative geometry characterized by a gauge-type field strength of the gravifield. A coordinate-independent and gauge-invariant action for the quantum gravity is built in the gravifield basis. In the coordinate basis, we derive equations of motion for all quantum fields including the gravitational effect and obtain basic conservation laws for all symmetries. The equation of motion for the gravifield tensor is deduced in connection directly with the total energy-momentum tensor. Two types of gravity equation result; one is as the extension to Einstein's equation of general relativity, and the other is a new one that characterizes spinon dynamics. The Einstein theory of general relativity is considered to be an effective low-energy theory.
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