PubMed Health⌕ Search

Biomedical subjects

E Tirapegui

Publications and source records attributed to E Tirapegui.

11 recordsLinked to original sources
PubMed2006

Pattern formation and localized structures in reaction-diffusion systems with non-Fickian transport.

We study the robust dynamical behaviors of reaction-diffusion systems where the transport gives rise to non-Fickian diffusion. A prototype model describing the deposition of molecules in a surface is used to show the generic appearance of Turing structures which can coexist with homogeneous states giving rise to localized structures through the pinning mechanism. The characteristic lengths of these structures are in the nanometer region in agreement with recent experimental observations.

Journal Article↗
PubMed2006

Front propagation sustained by additive noise.

The effect of noise in a motionless front between a periodic spatial state and an homogeneous one is studied. Numerical simulations show that noise induces front propagation. From the subcritical Swift-Hohenberg equation with noise, we deduce an adequate equation for the envelope and the core of the front. The equation of the core of the front is characterized by an asymmetrical periodic potential plus additive noise. The conversion of random fluctuations into direct motion of the core of the front is responsible of the propagation. We obtain an analytical expression for the velocity of the front, which is in good agreement with numerical simulations.

Journal Article↗
PubMed2005

Coarsening dynamics of the one-dimensional Cahn-Hilliard model.

The dynamics of one-dimensional Cahn-Hilliard model is studied. The stationary and particle-type solutions, the bubbles, are perused as a function of initial conditions, boundary conditions, and system size. We characterize the bubble solutions which are involved in the coarsening dynamics and establish the bifurcation scenarios of the system. A set of ordinary differential equation permits us to describe the coarsening dynamics in very good agreement with numerical simulations. We also compare these dynamics with the bubble dynamics deduced from the classical kink interaction computation where our model seems to be more appropriated. In the case of two bubbles, we deduce analytical expressions for the bubble's position and the bubble's width. Besides, a simple description of the ulterior dynamics is presented.

Journal Article↗
PubMed2005

Additive noise induces front propagation.

The effect of additive noise on a static front that connects a stable homogeneous state with an also stable but spatially periodic state is studied. Numerical simulations show that noise induces front propagation. The conversion of random fluctuations into direct motion of the front's core is responsible of the propagation; noise prefers to create or remove a bump, because the necessary perturbations to nucleate or destroy a bump are different. From a prototype model with noise, we deduce an adequate equation for the front's core. An analytical expression for the front velocity is deduced, which is in good agreement with numerical simulations.

Journal Article↗
PubMed2000

Bubbles interactions in the cahn-hilliard equation

We study the dynamics of bubbles in the one dimensional Cahn-Hilliard equation. For a gas of diluted bubbles we find ordinary differential equations describing their interaction which permits us to describe the ulterior dynamics of the system in very good agreement with numerical simulations.

Journal Article↗
PubMed1994

[Results of combined treatment of early cervicouterine cancer].

Forty nine patients with carcinoma of the cervix treated with a combined method of preoperative radiation therapy (telecobalto and intracavitary) followed by extrafascial hysterectomy are presented. The average age was 39.6 years old. All tumors measured more than 4 cm, in diameter. The staging was lb = 40; lla = 6; llb = 3. The hysterectomy was done average 7.3 weeks after radiation therapy. Postreatment complications were seen in 32.4% and long term complications were found in 8.1% of the cases. After three years of follow up 91% of the patients were free of neoplastic disease. The 40% of the cases has more than three years follow up. There was 14% of total mortality which includes 10.2% of mortality by cancer. The size of the tumor (initially more than 7 cm, in diameter) and the finding of the tumor tissue in the surgical specimens were found of poor prognosis. There was significant statistical difference in survival between the groups with and without cancer cells in the uterus after hysterectomy (p < 0.01).

Adult↗