Chiral selection and frequency response of spiral waves in reaction-diffusion systems under a chiral electric field

Chirality is one of the most fundamental properties of many physical, chemical and biological systems. However, the mechanisms underlying the onset and control of chiral symmetry are largely understudied. We investigate possibility of chirality control in a chemical excitable system (the BZ reaction) by application of a chiral (rotating) electric field using the Oregonator model. We find that unlike previous findings, we can achieve the chirality control not only in the field rotation direction, but also opposite to it, depending on the field rotation frequency. To unravel the mechanism, we further develop a comprehensive theory of frequency synchronization based on the response function approach. We find that this problem can be described by the Adler equation and show phase-locking phenomena, known as the Arnold tongue. Our theoretical predictions are in good quantitative agreement with the numerical simulations and provide a solid basis for chirality control in excitable media.Comment: 21 pages with 9 figures; update references; to appear in J. Chem. Phy

Increased Levels of C1q in the prefrontal cortex of adult offspring after maternal immune activation: Prevention by 7,8-dihydroxyflavone

Objective: Prenatal infection is implicated in the etiology of schizophrenia. The objective of this paper is to study the role of complement protein C1q in the psychosis of adult offspring after maternal immune activation (MIA). In addition, effect of 7,8-dihydroxyflavone (7,8-DHF: A tropomyosin receptor kinase B [TrkB] agonist) was also examined. Methods: Western blot analysis of C1q in the brain regions from adult offspring after prenatal poly(I:C) (5.0 mg/kg/day from E12 to E17) exposure was performed. 7,8-DHF or vehicle was given from 4 to 8-weeks old. Results: Expression of C1q in the prefrontal cortex (PFC) of adult offspring from poly(I:C)-Treated pregnant mice was significantly higher than that of control group. Early treatment with 7,8-DHF during juvenile and adolescent stages could prevent an increase of C1q in the PFC of adult offspring after MIA. Conclusion: Therefore, it is likely that increased C1q expression in the frontal cortex may play a role in the behavioral abnormalities of adult offspring after MIA. Furthermore, supplementation with a TrkB agonist such as 7,8-DHF during the prodromal stage may have prophylactic effects on the behavioral abnormalities after MIA

Phase-locked scroll waves defy turbulence induced by negative filament tension

Scroll waves in a three-dimensional media may develop into turbulence due to negative tension of the filament. Such negative tension-induced instability of scrollwaves has been observed in the Belousov-Zhabotinsky reaction systems. Here we propose a method to restabilize scroll wave turbulence caused by negative tension in three-dimensional chemical excitable media using a circularly polarized (rotating) external field. The stabilization mechanism is analyzed in terms of phase-locking caused by the external field, which makes the effective filament tension positive. The phase-locked scrollwaves that have positive tension and higher frequency defy the turbulence and finally restore order. A linear theory for the change of filament tension caused by a generic rotating external field is presented and its predictions closely agree with numerical simulations