• 대한수학회보
• /
• 제61권2호
• /
• pp.479-488
• /
• 2024

Convergence to a steady state in the long term limit is established for global weak solutions to a chemotaxis model with degenerate local sensing and consumption, when the motility function is C¹-smooth on [0, ∞), vanishes at zero, and is positive on (0, ∞). A condition excluding that the large time limit is spatially homogeneous is also provided. These results extend previous ones derived for motility functions vanishing algebraically at zero and rely on a completely different approach.

• KSBB Journal
• /
• 제13권4호
• /
• pp.449-455
• /
• 1998

The bacterial motility in sand was studied with Alcaligenes xylosoxidans Y234 which is known as a strong decomposer of aromatic chemicals, especially toluene. Apparent motility coefficient (${\mu}$c,app) and apparent chemotaxis coefficient (${\mu}$c,app) for toluene were measured in the sands which have four different porosities. Adsorption ratio of Alcaligenes xylosoxidans Y234 on the sands was measured as 17%. The ramdom motility coefficients were 0.85∼1.68${\times}$10-3$\textrm{cm}^2$/sec, and decreased as the porosity of sands decreased. Apparent chemotaxis coefficients were measured as 1.1∼6.8${\times}$10-5$\textrm{cm}^2$/sec, and decreased as the porosity decreased and with time. The tendency of alcaligenes xylosoxidans Y234 movement towards toluene seemed very weak and showed little chemotaxis.

• Kyungpook Mathematical Journal
• /
• 제63권2호
• /
• pp.141-154
• /
• 2023

We study the stability of traveling waves of a certain chemotaxis model. The traveling wave solution is a central object of study in a chemotaxis model. Kim et al. [8] introduced a model on a population and nutrient densities based on a nonlinear diffusion law. They proved the existence of traveling waves for the one dimensional Cauchy problem. Existence theory for traveling waves is typically followed by stability analysis because any traveling waves that are not robust against a small perturbation would have little physical significance. We conduct a numerical nonlinear stability for a few relevant instances of traveling waves shown to exist in [8]. Results against absolute additive noises and relative additive noises are presented.

• 대한수학회지
• /
• 제37권5호
• /
• pp.721-733
• /
• 2000

A paeabolic-elliptic system modelling chemotaxis is analysed. We study the behavior of solutions, especially the finite-time blowup of nonradial dolutions, to parabolic-elliptic system of n(n 2).

• 대한기계학회논문집B
• /
• 제31권3호
• /
• pp.209-216
• /
• 2007

Bacterial chemotaxis is essential to the study of structure and function of bacteria. Although many studies have accumulated the knowledge about chemotaxis in the past, the motion of a single bacterium has not been studied much yet. In this study, we have developed a device microfabricated by soft lithography and consisting of microfluidic channels. The microfluidic assay generates a concentration gradient of chemoattractant linearly in the main channel by only diffusion of the chemicals. Bacteria are injected into the main channel in a single row by hydrodynamic focusing technique. We measured the velocity of bacteria in response to a given concentration gradient of chemoattractant using the microfludic assay, optical systems with CCD camera and simple PTV (Particle Tracking Velocimetry) algorithm. The advantage of this assay and experiment is to measure the velocity of a single bacterium and to quantify the degree of chemotaxis by statistically analyzing the velocity at the same time. Specifically, we measured and analyzed the motility of Escherichia coli strain RP437 in response to various concentration gradients of L-aspartate statistically and quantitatively by using this microfluidic assay. We obtained the probability density of the velocity while RP437 cells are swimming and tumbling in the presence of the linear concentration gradient of L-aspartate, and quantified the degree of chemotaxis by analyzing the probability density.

• Journal of Periodontal and Implant Science
• /
• 제25권2호
• /
• pp.279-289
• /
• 1995

The most important object of periodontal treatment is the perfect regeneration of destructed periodontal tissue. The healing of periodontal lesion is affected by several cells & factors, which result in formation of long juntional epithelium, root resorption, bony ankylosis or connective tissue attachment. And ideal healing is enhanced by epithilial exclusion or periodontal ligament cell activation. In this investigation, I studied the effect of Zizyphus Fructus extract which enhances biologic activity& collagen synthesis, on the chemotaxis & cell nature. The cells were obtained from interdental area & middle third area of the freshly extracted teeth for the orthodontic purpose. And they were fully incubated in${\alpha}-MEM$ solution containing $100{\mu]g/ml$ penicillin & $100{\mu]g/ml$ streptomycin followed by 6 generation incubation. The test cells were collected by trypsin-EDTA & centrifuge in the fully incubated cells, counted by Hernacyotmeter, incbated $5{\times}10^5/ml$ cells for 24 hours, re-incubated 24 hours in media containing natural extract and photographed. The cells were incubated for 4 hours in 48 well microchemotaxis chamber bisecting upper & lower chamber by 8ug/m pore polycarbonate membrane coating 5mg/ml gelatin solution. The migrated cells in microscope were counted, which meaned cell chemotaxis activity. The study had shown that the morphology of cell was spindle-shaped as the control group, and the subextract test groups were not significantly different. In gingival fibroblasts, the chemotaxis effect of PDGF was statistically significant compared to control group. The Zizyphus Fructus extract was more or less enhanced chemotaxis effect and in $1{\mu}g/ml$ concentration the chemotaxis effect was slightly elevated compared with $10{\mu}g/ml$ concentration. But, among the subextracts, it was not significantly defferent. In PDL cells, the chemotaxis effect of PDGF in statistically significant, and the zizyphus Fructus extract had shown the enhanced effect. The effect was slightly higher in $1{\mu}g/ml$ concentration than 10g/ml concentration,and no significance among the subextracts.

• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2005년도 창립60주년 기념 추계 학술대회
• /
• pp.58.2-58.2
• /
• 2005

• 대한수학회지
• /
• 제60권3호
• /
• pp.619-634
• /
• 2023

This paper considers a parabolic-hyperbolic-hyperbolic type chemotaxis system in ℝ^d, d ≥ 3, describing tumor-induced angiogenesis. The global existence result and temporal decay estimate for a unique mild solution are established under the assumption that some Sobolev norms of initial data are sufficiently small.

• Asian-Australasian Journal of Animal Sciences
• /
• 제17권8호
• /
• pp.1145-1149
• /
• 2004

Immunomodulatory feed additives might offer alternatives to antimicrobial growth promoters in poultry production. This experiment was carried out to test the effect of $\beta$-glucan supplementation on the growth performance and immune response in broilers. Total of 160 day-old broilers were randomly assigned to 4 treatment groups fed corn-soybean diets containing 0, 0.012, 0.025 or 0.05% of $\beta$-glucan supplement in a 6 week feeding experiment. Growth performance, antibody titer against New Castle vaccine, lymphocyte blastogensis, and peritoneal macrophage chemotaxis activity of broilers were evaluated. Results showed that there were no significant differences in weight gain and feed efficiency among the treatments, and no differences in antibody titer was observed. Supplementation of $\beta$-glucan did not elevate the lymphocyte blastogensis among treatments, following stimulation with different mitogens. However, supplementation with 0.025 and 0.05% $\beta$-glucan enhanced the macrophage chemotaxis activity of broilers. These results suggest that $\beta$-glucan may enhance some cell-mediated immune responses of chickens by modulate macrophages ability.

• 자연과학논문집
• /
• 제10권1호
• /
• pp.39-47
• /
• 1998

본 실험은 대식세포 화학주성과 세포내 칼슘과 F-actin 증가에 대한 인삼사포닌 분획의 영향을 알아보기 위하여 수행되었다. 여러 가지 인삼사포닌 분획을 처리한 복강 대식세포는 대조군에 비해 화학주성이 28.4-71% 증가하였다. 세포내에 유리된 칼슘의 양은 65%까지 증가하였으며, NBD- phallacidin을 처리한 세포에서 F-actin의 양은 10% 증가하였다. 칼슘이나 PMA로 활성화시키고 사포닌 분획을 처리하였을 때, F-actin의 양은 현저하게 증가하였으며 이러한 현상은 2분까지 지속되었다. 이러한 결과로 보아 인삼사포닌 분획이 chemoattractant로 작용할 수 있을 것으로 생각된다.