Biomedical subjects

X T He

Publications and source records attributed to X T He.

6 recordsLinked to original sources

PubMed2006

X-wave solutions of complex Ginzburg-Landau equations.

A solution in the form of X-wave patterns of the complex Ginzburg-Landau equation with a harmonic background inhomogeneity is obtained. The pattern can be attributed to the effects of the harmonic potential and the boundary configuration and size. By varying the harmonic of the background potential, the competition among three types of wave patterns: spiral, X, and target, is investigated by following the evolution of the Fourier modes.

Journal Article↗

PubMed2006

A note on chaotic unimodal maps and applications.

Based on the word-lift technique of symbolic dynamics of one-dimensional unimodal maps, we investigate the relation between chaotic kneading sequences and linear maximum-length shift-register sequences. Theoretical and numerical evidence that the set of the maximum-length shift-register sequences is a subset of the set of the universal sequence of one-dimensional chaotic unimodal maps is given. By stabilizing unstable periodic orbits on superstable periodic orbits, we also develop techniques to control the generation of long binary sequences.

Algorithms↗

PubMed2004

Resonance acceleration of electrons in combined strong magnetic fields and intense laser fields.

The acceleration mechanism of electrons in combined strong axial magnetic fields and circularly polarized laser pulse fields is investigated by solving the dynamical equations for relativistic electrons both numerically and analytically. We find that the electron acceleration depends not only on the laser intensity, but also on the ratio between electron Larmor frequency and laser frequency. As the ratio approaches unity, a clear resonance peak is observed, corresponding to the laser-magnetic resonance acceleration. Away from the resonance regime, the strong magnetic fields still affect the electron acceleration dramatically. We derive an approximate analytical solution of the relativistic electron energy in adiabatic limit, which provides a full understanding of this phenomenon. Application of our theory to fast ignition of inertial confinement fusion is discussed.

Journal Article↗

PubMed2002

Harmonic modulation instability and spatiotemporal chaos.

It is shown from the conserved Zakharov equations that many solitary patterns are formed from the modulational instability of unstable harmonic modes that are excited by a perturbative wave number. Pattern selection in our case is discussed. It is found that the evolution of solitary patterns may appear in three states: spatiotemporal coherence, chaos in time but the partial coherence in space, and spatiotemporal chaos. The spatially partial coherent state is essentially due to ion-acoustic wave emission, while spatiotemporal chaos characterized by its incoherent patterns in both space and time is caused by collision and fusion among patterns in stochastic motion. So energy carried by patterns in the system is redistributed.

Journal Article↗

PubMed2002

Stabilization of ablative Rayleigh-Taylor instability due to change of the Atwood number.

Recent experiment [S.G. Glendinning et al., Phys. Rev. Lett. 78, 3318 (1997)] showed that the measured growth rate of laser ablative Rayleigh-Taylor (RT) instability with preheating is about 50% of the classic value and is reduced by about 18% compared with the simulated value obtained with the computer code LASNEX. By changing the temperature variation of the electron thermal conductivity at low temperatures, the density profile from the Bhatnagar-Gross-Krook approximation is recovered in the simulation, and the simulated RT growth rate is in good agreement with the experimental value from Glendinning et al. The preheated density profile on ablative RT stablization is studied numerically. A change of the Atwood number in the preheating case also leads to RT stabilization. The RT growth formula gamma=square root of [Akg/(1+AkL)] - 2kV(a) agrees well with experiment and simulation, and is appropriate for the preheating case.

Journal Article↗

PubMed2001

Expression, deletion [was deleton] and mutation of p16 gene in human gastric cancer.

AIM: To investigate the relationship between the expression of p16 gene and the gastric carcinogenesis, depth of invasion and lymph node metastases, and to evaluate the deletion and mutation of exon 2 in p16 gene in gastric carcinoma. METHODS: The expression of p16 protein was examined by streptavidin-peroxidase conjugated method (S-P);the deletion and mutation of p16 gene were respectively examined by polymerase chain reaction (PCR) and polymerase chain reaction single-strand conformation polymorphism analysis (PCR-SSCP) in gastric carcinoma. RESULTS: Expression of p16 protein was detected in 96.25% (77/80) of the normal gastric mucosa, in 92.00% (45/50) of the dysplastic gastric mucosa and in 47.54% (58/122) of the gastric carcinoma. The positive rate of p16 protein expression in gastric carcinoma was significantly lower than that in normal gastric mucosa and dysplastic gastric mucosa (P < 0.05). The positive rate of p16 protein expression in mucoid carcinoma 10.00% (1/10) was significantly lower than that in poorly differentiated carcinoma 51.22% (21/41), undifferentiated carcinoma 57.69% (15/26) and signet ring cell carcinoma 62.50% (10/16) (P < 0.05). The positive rate of p16 protein in 30 cases paired primary and lymph node metastatic gastric carcinoma: There was 46.67% (14/30) in primary gastric carcinoma, 16.67% (5/30) in lymph node metastatic gastric carcinoma. The positive rate of lymph node metastatic carcinoma was significantly lower than that of primary carcinoma (P < 0.05). There was of p16 gene mutation in exon 2, but 5 cases displayed deletion of p16 gene in exon 2 in the 25 primary gastric carcinomas. CONCLUSIONS: The expression loss of p16 protein related to the gastric carcinogenesis, gastric carcinoma histopathological subtypes and lymph metastasis. The mutation of p16 gene in exon 2 may not be involved in gastric carcinogenesis. But the deletion of p16 gene in exon 2 may be involved in gastric carcinogenesis.

Adult↗