1,768 research outputs found
Snyder's Model -- de Sitter Special Relativity Duality and de Sitter Gravity
Between Snyder's quantized space-time model in de Sitter space of momenta and
the \dS special relativity on \dS-spacetime of radius with Beltrami
coordinates, there is a one-to-one dual correspondence supported by a minimum
uncertainty-like argument. Together with Planck length , should be a fundamental constant. They lead to a
dimensionless constant . These indicate that physics at these two scales should be dual to
each other and there is in-between gravity of local \dS-invariance
characterized by . A simple model of \dS-gravity with a gauge-like action on
umbilical manifolds may show these characters. It can pass the observation
tests and support the duality.Comment: 32 page
Newton-Hooke Limit of Beltrami-de Sitter Spacetime, Principles of Galilei-Hooke's Relativity and Postulate on Newton-Hooke Universal Time
Based on the Beltrami-de Sitter spacetime, we present the Newton-Hooke model
under the Newton-Hooke contraction of the spacetime with respect to the
transformation group, algebra and geometry. It is shown that in Newton-Hooke
space-time, there are inertial-type coordinate systems and inertial-type
observers, which move along straight lines with uniform velocity. And they are
invariant under the Newton-Hooke group. In order to determine uniquely the
Newton-Hooke limit, we propose the Galilei-Hooke's relativity principle as well
as the postulate on Newton-Hooke universal time. All results are readily
extended to the Newton-Hooke model as a contraction of Beltrami-anti-de Sitter
spacetime with negative cosmological constant.Comment: 25 pages, 3 figures; some misprints correcte
Constraining neutrino mass in dynamical dark energy cosmologies with the logarithm parametrization and the oscillating parametrization
We constrain two dynamical dark energy models that are parametrized by the
logarithm form of
and the oscillating form of
. Comparing with
the Chevallier-Polarski-Linder (CPL) model, the two parametrizations for dark
energy can explore the whole evolution history of the universe properly. Using
the current mainstream observational data including the cosmic microwave
background data and the baryon acoustic oscillation data as well as the type Ia
supernovae data, we perform the statistic analysis to global fit these
models, finding that the logarithm parametrization and the oscillating
parametrization are almost as well as the CPL scenario in fitting these data.
We make a comparison for the impacts of the dynamical dark energy on the
cosmological constraints on the total mass of active neutrinos. We find that
the dark energy properties could significantly change the fitting results of
neutrino mass. Looser constraints on are obtained in the
logarithm and oscillating models than those derived in the CPL model.
Consideration of the possible mass ordering of neutrinos reveals that the most
stringent constraint on appears in the degenerate hierarchy
case
Upregulation of Endogenous HMOX1 Expression by a Computer-Designed Artificial Transcription Factor
Heme oxygenase-1 (HO-1) is well known as a cytoprotective factor. Research has revealed that it is a promising therapeutic target for cardiovascular diseases. In the current study, an HMOX1 (HO-1 gene) enhancer-specific artificial zinc-finger protein (AZP) was designed using bioinformatical methods. Then, an artificial transcription factor (ATF) was constructed based on the AZP. In the ATF, the p65 functional domain was used as the effector domain (ED), and a nuclear localization sequence (NLS) was also included. We next analyzed the affinity of the ATF to the HMOX1 enhancer and the effect of the ATF on endogenous HMOX1 expression. The results suggest that the ATF could effectively upregulate endogenous HMOX1 expression in ECV304 cells. With further research, the ATF could be developed as a potential drug for cardiovascular diseases
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