Transition from rotating waves to modulated rotating waves on the sphere

We study non-resonant and resonant Hopf bifurcation of a rotating wave in SO(3)-equivariant reaction-diffusion systems on a sphere. We obtained reduced differential equations on so(3), the characterization of modulated rotating waves obtained by Hopf bifurcation of a rotating wave, as well as results regarding the resonant case. Our main tools are the equivariant center manifold reduction and the theory of Lie groups and Lie algebras, especially for the group SO(3) of all rigid rotations on a sphere

The ROCK inhibitor Fasudil prevents chronic restraint stress-induced depressive-like behaviors and dendritic spine loss in rat hippocampus

Indexación: Web of Science; Scopus.Background: Dendritic arbor simplification and dendritic spine loss in the hippocampus, a limbic structure implicated in mood disorders, are assumed to contribute to symptoms of depression. These morphological changes imply modifications in dendritic cytoskeleton. Rho GTPases are regulators of actin dynamics through their effector Rho kinase. We have reported that chronic stress promotes depressive-like behaviors in rats along with dendritic spine loss in apical dendrites of hippocampal pyramidal neurons, changes associated with Rho kinase activation. The present study proposes that the Rho kinase inhibitor Fasudil may prevent the stress-induced behavior and dendritic spine loss. Methods: Adult male Sprague-Dawley rats were injected with saline or Fasudil (i.p., 10 mg/kg) starting 4 days prior to and maintained during the restraint stress procedure (2.5 h/d for 14 days). Nonstressed control animals were injected with saline or Fasudil for 18 days. At 24 hours after treatment, forced swimming test, Golgi-staining, and immuno-western blot were performed. Results: Fasudil prevented stress-induced immobility observed in the forced swimming test. On the other hand, Fasudiltreated control animals showed behavioral patterns similar to those of saline-treated controls. Furthermore, we observed that stress induced an increase in the phosphorylation of MYPT1 in the hippocampus, an exclusive target of Rho kinase. This change was accompanied by dendritic spine loss of apical dendrites of pyramidal hippocampal neurons. Interestingly, increased pMYPT1 levels and spine loss were both prevented by Fasudil administration. Conclusion: Our findings suggest that Fasudil may prevent the development of abnormal behavior and spine loss induced by chronic stress by blocking Rho kinase activity.https://academic.oup.com/ijnp/article/20/4/336/263217

Electrochemical Carbonylation of Organoiron Methyl Complex: A Study of Reaction Intermediates

The one-electron reduction of CpFe(CO)2CH3 has been investigated by voltammetry and Fourier transform IR spectroelectrochemistry. The reduction initiates the insertion of CO ligand in the FeCH3 bond. The dissociation of a CO group proceeds in a parallel reaction. Reaction intermediates, the acyl derivative and released CO, form the radical anion of a complex CpFe(CO)2(COCH3) which is able to reduce the parent compound. The reversible redox potential − 1.8 V of CpFe(CO)2(COCH3) allows the regeneration of its radical anion which drives a catalytic cycle. The lifetime of intermediates is shortened by side reactions, one of which is the migration of the acyl group from the central atom to the cyclopentadienyl ring. This explains the apparent discrepancy between products observed in preparative scale electrolysis and the absence of catalytic effects in routine voltammetric experiments

Forced Symmetry Breaking from SO(3) to SO(2) for Rotating Waves on the Sphere

We consider a small SO(2)-equivariant perturbation of a reaction-diffusion system on the sphere, which is equivariant with respect to the group SO(3) of all rigid rotations. We consider a normally hyperbolic SO(3)-group orbit of a rotating wave on the sphere that persists to a normally hyperbolic SO(2)-invariant manifold $M(\epsilon)$. We investigate the effects of this forced symmetry breaking by studying the perturbed dynamics induced on $M(\epsilon)$ by the above reaction-diffusion system. We prove that depending on the frequency vectors of the rotating waves that form the relative equilibrium SO(3)u_{0}, these rotating waves will give SO(2)-orbits of rotating waves or SO(2)-orbits of modulated rotating waves (if some transversality conditions hold). The orbital stability of these solutions is established as well. Our main tools are the orbit space reduction, Poincare map and implicit function theorem

A striking correspondence between the dynamics generated by the vector fields and by the scalar parabolic equations

The purpose of this paper is to enhance a correspondence between the dynamics of the differential equations $\dot y(t)=g(y(t))$ on $\mathbb{R}^d$ and those of the parabolic equations $\dot u=\Delta u +f(x,u,\nabla u)$ on a bounded domain $\Omega$. We give details on the similarities of these dynamics in the cases $d=1$, $d=2$ and $d\geq 3$ and in the corresponding cases $\Omega=(0,1)$, $\Omega=\mathbb{T}^1$ and dim($\Omega$)$\geq 2$ respectively. In addition to the beauty of such a correspondence, this could serve as a guideline for future research on the dynamics of parabolic equations

Thoroughbred Racehorse Welfare through the Lens of ‘Social License to Operate—With an Emphasis on a U.S. Perspective

This review addresses the question of whether Thoroughbred horse racing is sustainable in the context of current social values. A recently acknowledged framework, known as ‘Social License to Operate’ (SLO), provides us with a lens through which to view and assess racehorse welfare. In multiple surveys of the general public, the horse owning public, and university students, the primary topics of concern regarding Thoroughbred racing show considerable concordance: concern about catastrophic injuries—particularly as related to track surfaces, concern over the racing of two-year-olds, whip use by jockeys, drug/medication policies, and aftercare opportunities for retired Thoroughbred racehorses. Legitimacy of an industry, consent from industry stakeholders, and trust between the community players, are all essential to have and maintain SLO. In the current era of 24/7 global media access, and the proliferation of social media providing an interactive platform for all interested parties, a dramatic change has occurred in commentary related to racehorse welfare concerns. The situation at Santa Anita (California, USA) from late December 2018 through mid-November 2019 demonstrated just how tenuous the SLO for horse racing is. This article will provide a brief review of what ‘Social License to Operate’ is, along with a brief literature review of five of the areas of primary concern voiced by stakeholders

Judging the impact of leadership-development activities on school practice

The nature and effectiveness of professional-development activities should be judged in a way that takes account of both the achievement of intended outcomes and the unintended consequences that may result. Our research project set out to create a robust approach that school staff members could use to assess the impact of professional-development programs on leadership and management practice without being constrained in this judgment by the stated aims of the program. In the process, we identified a number of factors and requirements relevant to a wider audience than that concerned with the development of leadership and management in England. Such an assessment has to rest upon a clear understanding of educational leadership,a clearly articulated model of practice, and a clear model of potential forms of impact. Such foundations, suitably adapted to the subject being addressed, are appropriate for assessing all teacher professional development

Fresnel laws at curved dielectric interfaces of microresonators

We discuss curvature corrections to Fresnel's laws for the reflection and transmission of light at a non-planar refractive-index boundary. The reflection coefficients are obtained from the resonances of a dielectric disk within a sequential-reflection model. The Goos-H\"anchen effect for curved light fronts at a planar interface can be adapted to provide a qualitative and quantitative extension of the ray model which explains the observed deviations from Fresnel's laws.Comment: submitted to Phys. Rev.

Using the quality circle approach to empower disadvantaged youth in addressing cyberbullying: an exploration across five European countries

Digital communication technologies play an important role in the social development of young people, but can create vulnerabilities to cyberbullying and other negative online experiences. The Blurred Lives project aimed to tackle cyberbullying innovatively using a co-participatory approach, collaborating with 14–16-year olds living in areas of socio-economic disadvantage in five European countries. In phase one, 2,658 teenagers were surveyed on their internet use and any unpleasant online experiences. This data informed the second phase where the participating countries worked together with 237 adolescents across 10 schools with adult facilitators to create original anti-cyberbullying resources for teachers, parents/carers, peers, and social media providers using the Quality Circle approach. This methodology adopts an ethos of working together to solve a problem in small, peer-led groups. Each group was tasked with creating a resource for one of the target audience groups. The final resources comprise a rich variety of different formats including videos, comic strips, a board game, leaflets, posters, and newsletters. The pupil feedback highlights, for most but not all participants, an increased knowledge of cyberbullying and e-safety skills, as well as enhanced problem-solving skills, levels of confidence, and group work skills. Several operational challenges are also discussed, including the importance of school-level support, planning, staffing, and finding an appropriate balance between facilitator support and pupil agency