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De-Hai Zhang

Publications and source records attributed to De-Hai Zhang.

12 recordsLinked to original sources
arXiv2016

A pathway-based network analysis of hypertension-related genes

Complex network approach has become an effective way to describe interrelationships among large amounts of biological data, which is especially useful in finding core functions and global behavior of biological systems. Hypertension is a complex disease caused by many reasons including genetic, physiological, psychological and even social factors. In this paper, based on the information of biological pathways, we construct a network model of hypertension-related genes of the salt-sensitive rat to explore the interrelationship between genes. Statistical and topological characteristics show that the network has the small-world but not scale-free property, and exhibits a modular structure, revealing compact and complex connections among these genes. By the threshold of integrated centrality larger than 0.71, seven key hub genes are found: Jun, Rps6kb1, Cycs, Creb3l2, Cdk4, Actg1 and RT1-Da. These genes should play an important role in hypertension, suggesting that the treatment of hypertension should focus on the combination of drugs on multiple genes.

q-bio.MN↗
arXiv2010

Grand Unified Yukawa Matrix Ansatz: The Standard Model Fermion Mass, Quark Mixing and CP Violation Parameters

We propose a new mass matrix ansatz: At the grand unified (GU) scale, the standard model (SM) Yukawa coupling matrix elements are integer powers of the square root of the GU gauge coupling constant \varepsilon \equiv \sqrt{α_{\text{GU}}}, multiplied by order unity random complex numbers. It relates the hierarchy of the SM ermion masses and quark mixings to the gauge coupling constants, greatly reducing the SM parameters, and can give good fitting results of the SM fermion mass, quark mixing and CP violation parameters. This is a neat but very effective ansatz.

hep-ph↗
arXiv2006

A Cyclic Cosmological Model in the Landscape Scenario

In [1], KKLT give a mechanism to generate de Sitter vacua in string theory. And the scenario, \emph{Landscape}, is suggested to explain the problem of the cosmological constant. In this paper, adopting a simple potential describing the \emph{landscape}, we investigate the decay of the vacuum and the evolution of the universe after the decay. We find that the big crunch of the universe is inevitable. But, according to the modified Friedmann equation in [11], the singularity of the big crunch is avoided. Furthermore, we find that this gives a cyclic cosmological model.

hep-th↗
arXiv2003

The Exact Evolution Equation of the Curvature Perturbation for Closed Universe

As is well known, the exact evolution equation of the curvature perturbation plays a very important role in investigation of the inflation power spectrum of the flat universe. However, its corresponding exact extension for the non-flat universes has not yet been given out clearly. The interest in the non-flat, specially closed, universes is being aroused recently. The need of this extension is pressing. We start with most elementary physical consideration and obtain finally this exact evolution equation of the curvature perturbation for the non-flat universes, as well as the evolutionary controlling parameter and the exact expression of the variable mass in this equation. We approximately do a primitive and immature analysis on the power spectrum of non-flat universes. This analysis shows that this exact evolution equation of the curvature perturbation for the non-flat universes is very complicated, and we need to do a lot of numerical and analytic work for this new equation in future in order to judge whether the universe is flat or closed by comparison between theories and observations.

astro-ph↗
arXiv2001

The Eventual Quintessential Big Collapse of the Closed Universe with the Present Accelerative Phase

Whether our universe with present day acceleration can eventually collapse is very interesting problem. We are also interesting in such problems, whether the universe is closed? Why it is so flat? How long to expend a period for a cycle of the universe? In this paper a simple ``slow-fast'' type of the quintessence potential is designed for the closed universe to realize the present acceleration of our universe and its eventual big collapse. A detail numerical simulation of the universe evolution demonstrates that it divides the seven stages, a very rich story. It is unexpected that the quintessential kinetic energy is dominated in the shrink stage of the universe with very rapid velocity of the energy increasing. A complete analytic analysis is given for each stage. Some very interesting new problems brought by this collapse are discussed. Therefore our model avoids naturally the future event horizon problem of the present accelerative expanding universe and maybe realize the infinite cycles of the universe, which supplies a mechanism to use naturally the anthropic principle. This paper shows that the understanding on the essence of the cosmological constant should contain a richer content.

astro-ph↗
arXiv2000

The First Acoustics Peak CMBR and Cosmic Total Density

Boomerang measured the first peak in CMBR to be at location of $l_D=196\pm 6$, which excites our strong interesting in it. A widely cited formula is $l_D\simeq 200Ω_T^{-0.50}$ to estimate the cosmic total density. Weinberg shows it is not correct and should be $l_D\propto Ω_T^{-1.58}$ near the interest point $(Ω_m,Ω_Λ)=(0.3,0.7)$. We show further that it should be $l_D\propto Ω_T^{-1.43}Ω_m^{-0.147}$ or $Ω_T^{-1.92}Ω_Λ^{0.343}$ near the same point in the more veracious sense if we consider the effect from the sound horizon. We draw a contour graph for the peak location, show that the recent data favor to a closed universe with about $Ω_T\simeq 1.03$. If we insist on obtaining a flat universe, a point $(0.36,0.64)$, i.e., more matter and less vacuum energy, is still possible, which has a more right-side first peak $l_D=208$ in CMBR and a smaller acceleration parameter $-q_0=0.10$ for the $z=0.4$ redshift SNIa.

astro-ph↗
arXiv2000

Quantum Creation of Closed Universe with Both Effects of Tunneling and Well

A new ''twice loose shoe'' method in the Wheeler-DeWitt equation of the universe wave function on the cosmic scale factor a and a scalar field $ϕ$ is suggested in this letter. We analysis the both affects come from the tunneling effect of a and the potential well effect of $ϕ$, and obtain the initial values $a_0$ and $ϕ_0$ about a primary closed universe which is born with the largest probability in the quantum manner. Our result is able to overcome the ''large field difficulty'' of the universe quantum creation probability with only tunneling effect. This new born universe has to suffer a startup of inflation, and then comes into the usual slow rolling inflation. The universe with the largest probability maybe has a ''gentle'' inflation or an eternal chaotic inflation, this depends on a new parameter q which describes the tunneling character.

gr-qc↗
arXiv1999

Future Destiny of Quintessential Universe and Constraint on Model from Deceleration Parameter

The evolution of the quintessence in various stages of the universe, the radiation-, matter-, and quintessence-dominated, is closely related with the tracking behavior and the deceleration parameter of the universe. We gave the explicit relation between the equation-of-state of the quintessence in the epoch of the matter-quintessence equality and the inverse power index of the quintessence potential, obtained the constraint on this potential parameter come from the present deceleration parameter, i.e., a low inverse power index. We point out that the low inverse power-law potential with a single term can not work for the tracking solution. In order to have both of the tracker and the suitable deceleration parameter it is necessary to introduce at least two terms in the quintessence potential. We give the future evolution of the quintessential universe.

astro-ph↗
arXiv1999

The Cosmological Constant as a Residual Energy in the Chaotic Inflationary Model

A new idea of the cosmological constant is proposed in this paper. Due to the horizon is limited, the quantum fluctuation of the inflaton field is not zero, a nonzero vacuum energy is remained as a residual inflationary energy of an unusual potential, however the true stable vacuum energy is zero fortunately. A unified model of the cosmological constant and the chaotic inflation is proposed, which satisfies almost all cosmological phenomenology and will can be tested by data of the cosmic large scale structure.

hep-ph↗
arXiv1995

Classical and Quantum Chaotic Behaviors of Two Colliding Harmonic Oscillators

We have systematically studied both classical and quantum chaotic behaviors of two colliding harmonic oscillators. The classical case falls in Kolmogorov-Arnold-Moser class. It is shown that there exists an energy threshold, above which the system becomes nonintegrable. For some values of the initial energy near the threshold, we have found that the ratio of frequencies of the two oscillators affects the Poincaré sections significantly. The largest Lyapunov character exponent depends linearly on the ratio of frequencies of the two oscillators away from the energy threshold in some chaotic regions, which shows that the chaotic behaviors of the system are mainly determined by the ratio. In the quantum case, for certain parameters, the distribution of the energy level spacings also varies with the ratio of frequencies of the two oscillators. The relation between the energy spectra and the ratio of frequencies of the two oscillators, the interaction constant, and the semi-classical quantization constant, is also investigated respectively.

chao-dyn↗