Biomedical subjects

Hongyu Guo

Publications and source records attributed to Hongyu Guo.

6 recordsLinked to original sources

PubMed2006

[Water regulation characteristics and stress resistance of Caragana opulens population in different habitats of Inner Mongolia plateau].

This paper studied the water regulation characteristics and stress resistance of Caragana opulens population in Helinger (semi-arid area) and Alashan (intensively arid area), aimed to understand the adaptation mechanisms of this population to arid environment. The results showed that compared with Helinger population, Alashan population had a higher content of osmotic adjustment substances in leaf cells, which resulted in a lower osmotic potential, and thus, stronger osmotic adjustment ability. The leaf water and free water contents of Alashan population were lower than those of Helinger population, while the bound water content and the ratio of bound water to free water of the former were higher than those of the latter. The leaf water potential of Alashan population was lower than that of Helinger population. Alashan population had a lower stomatal conductance than Helinger population, indicating that the former had stronger water adjustment ability. The malondialdehyde (MDA) content of Alashan population was higher than that of Helinger population, while the permeability of plasma membrane and the super-oxygen free radicals content of Alashan population were lower than those of Helinger population. It was suggested that Alashan population had a stronger ability in removing free radicals, and a higher stability of plasma membrane. C. opulens could adapt to arid environment through effective water adjustment and strong stress resistance.

Adaptation, Physiological↗

PubMed2005

3-D diffeomorphic shape registration on hippocampal data sets.

Matching 3D shapes is important in many medical imaging applications. We show that a joint clustering and diffeomorphism estimation strategy is capable of simultaneously estimating correspondences and a diffeomorphism between unlabeled 3D point-sets. Correspondence is established between the cluster centers and this is coupled with a simultaneous estimation of a 3D diffeomorphism of space. The number of clusters can be estimated by minimizing the Jensen-Shannon divergence on the registered data. We apply our algorithm to both synthetically warped 3D hippocampal shapes as well as real 3D hippocampal shapes from different subjects.

Algorithms↗

PubMed2004

Hierarchical structure description of spatiotemporal chaos.

We develop a hierarchical structure (HS) analysis for quantitative description of statistical states of spatially extended systems. Examples discussed here include an experimental reaction-diffusion system with Belousov-Zhabotinsky kinetics, the two-dimensional complex Ginzburg-Landau equation, and the modified FitzHugh-Nagumon equation, which all show complex dynamics of spirals and defects. We demonstrate that the spatial-temporal fluctuation fields in the above-mentioned systems all display the HS similarity property originally proposed for the study of fully developed turbulence [Phys. Rev. Lett. 72, 336 (1994)]]. The derived values of a HS parameter beta from experimental and numerical data in various physical regimes exhibit consistent trends and characterize the degree of turbulence in the systems near the transition, and the degree of heterogeneity of multiple disorders far from the transition. It is suggested that the HS analysis offers a useful quantitative description for the complex dynamics of two-dimensional spatiotemporal patterns.

Journal Article↗

PubMed2004

Chemical waves with line defects in the Belousov-Zhabotinsky reaction.

We report our experimental observations of line-defected chemical waves in a quasi-two-dimensional reaction-diffusion system of Belousov-Zhabotinsky reaction. The observed line defects are explicit, which can be directly monitored in real time. In the parameter space, the state of the chemical waves with line defects is located between two regimes of the defect-mediated turbulence. The line defects appear in target waves as well as in spiral waves. We demonstrate that the line defects come out in traveling waves as the later reorganize their spatial topologies to adapt to the change in the local dynamics from simple to complex oscillations or vice versa.

Journal Article↗

PubMed2002

Relation between the wave front and the tip movement of spirals.

The relation between the movement of spiral waves and their tip for a simple spiral is experimentally investigated in a spatial open reactor using the Belousov-Zhabotinsky reaction. In the quasi-two dimensional regime, our results agree with the combustion model proposed by Lázár et al. [Chaos 5, 443 (1995)] which states that the speed of spiral tip movement is proportional to the speed of spiral waves, c(tip) infinity c(front), when expressed in the radius of the spiral tip trajectory R and the spiral wavelength lambda, R infinity lambda. The measurement shows that the slope of the linear R-lambda curve is about 0.13, independent of the control parameter. This observation is also consistent with the combustion model.

Journal Article↗

PubMed2002

Experimental study of the dimensionality of black-eye patterns.

The spatial structure of one type of Turing pattern named "black eyes" is studied in experiments using the chlorite-iodide-malonic acid reaction in spatial open reactor. The purpose of the work is to verify (or falsify) two possible theoretical interpretations of black-eye pattern formation: the projection of a body-centered-cubic (bcc) structure onto the plane vertical to the body diagonal and the spatial resonance of larger wave vectors with the fundamental ones. The latter happens when the mode of the larger wave vectors becomes linearly unstable, as the system goes far beyond the onset of Turing bifurcation. Our experimental results give evidence that black-eye patterns are not a projection of the bcc structure, so that the interpretation of a three-dimensional structure can be ruled out. The observations in the experiment also suggest another possible mechanism for the formation of black eyes.

Journal Article↗