Developing the Concepts of Homeostasis, Homeorhesis, Allostasis, Elasticity, Flexibility and Plasticity of Brain Function

I discuss some concepts advanced for the understanding of the complex dynamics of brain functions, and relate them to approaches in affective, cognitive and action neurosciences. These functions involve neuro-glial interactions in a dynamic system that receives sensory signals from the outside of the central nervous system, processes information in frequency, amplitude and phase-modulated electrochemical waves, and control muscles and glands to generate behavioral patterns. The astrocyte network is in charge of controlling global electrochemical homeostasis, and Hodgkin–Huxley dynamics drive the bioelectric homeostasis of single neurons. In elastic processes, perturbations cause instability, but the system returns to the basal equilibrium. In allostatic processes, perturbations elicit a response from the system, reacting to the deviation and driving the system to stable states far from the homeostatic equilibrium. When the system does not return to a fixed point or region of the state space, the process is called homeorhetic, and may present two types of evolution: (a) In flexible processes, there are previously existing “attractor” stable states that may be achieved after the perturbation, depending on context; (b) In plastic processes, the homeostatic set point(s) is(are) changed; the system is in a process of adaptation, in which the allostatic forces do not drive it back to the previous set point, but project to the new one. In the temporal phase from the deviant state to the recovery of stability, the system generates sensations that indicate if the recovery is successful (pleasure-like sensations) or if there is a failure (pain-like sensations).

Medium-induced fragmentation and equilibration of highly energetic partons

We investigate the energy loss and equilibration of highly energetic particles/jets inside a QCD medium. Based on an effective kinetic description of QCD, including 2 ↔ 2 elastic processes, radiative 1 ↔ 2 processes, as well as the back-reaction of jet constituents onto the thermal medium, we describe the in-medium evolution of jets from the energy scale of the jet ∼ E all the way to the medium scale ∼ T. While elastic processes and back-reaction are important to describe the equilibration of soft fragments of the jet, we find that the energy loss is dominated by an inverse turbulent cascade due to successive radiative branchings, which has interesting implications for the energy spectra and chemistry of jet fragments.

Afro-Colombian internal migration and participatory music: Ethnically and politically charged religious festivals in Bogota

This paper reports an analysis of the roles of music performance in traditional patron saint celebrations from Afro-Colombian communities originally from the Pacific region but who currently live in the capital city of Bogotá. Since the late 1980s, a group of Afro-Colombian cultural leaders have used local traditional expressive cultural practices to construct social cohesion and a sense of collectivity among Afro-Colombians in the city. Here, I argue that the performative, expressive, and affective aspects inherent in Afro-Colombian patron saint celebrations can enable the potential of this transplanted practice for constructing ethnic identity and civic participation, thus catering to the needs of migrants and forcibly displaced people. Looking specifically at the case of the Virgin of Atocha saint wake in Bogotá, I discuss how several musicking, semiotic, and communicative techniques can be identified as facilitating social cohesion and cooperative behavior among participants. In this regard, creating an atmosphere overflowing with carefully selected social, expressive, cultural, and religious stimuli, as well as the idea of active participation, enables deep affective experiences that have an impact on elastic processes of identity construction and resignification of space and territory.

Three-dimensional modeling of hydrodynamic problems taking into account elastic processes

A finite-difference approximation of elastic forces on spaced Lagrangian grids is constructed, based on the method of support operators. For displacement vectors on irregular grids, on the topological and geometric structure of which minimal reasonable restrictions are imposed, the approximations of vector analysis operations are constructed in relation to difference schemes for problems of elasticity theory. Taking into account the energy balance of the medium, the constructed families of integrally consistent approximations of vector analysis operations are sufficient for discrete modeling of these processes. The schemes are considered, both using the stress tensor in an explicit form, and dividing it into spherical and shear components (pressure and deviator). The latter is used to construct homogeneous algorithms applicable to both the solid and the vaporized phase. The linear theory of elasticity is used for constructing approximations. The resulting forces in spatial geometry are obtained explicitly. Calculations of the sound waves propagation in a three-dimensional orthogonal aluminum plate due to end impact are presented. These calculations confirm the good quality of the difference schemes constructed in work.

Eikonal model analysis of elastic proton–proton collisions at 52.8 GeV and 8 TeV

Under the influence of standardly used description of Coulomb-hadronic interference proposed by West and Yennie the protons have been interpreted as transparent objects; elastic events have been interpreted as more central than inelastic ones. It will be shown that using eikonal model the protons may be interpreted in agreement with usual ontological conception; elastic processes being more peripheral than inelastic ones. The corresponding results (differing fundamentally from the suggested hitherto models) will be presented by analyzing the most ample elastic data set measured at the ISR energy of 52.8 GeV and the LHC energy of 8 TeV. Detailed analysis of measured differential cross section will be performed and possibility of peripheral behavior on the basis of eikonal model will be presented. The impact of recently established electromagnetic form factors on determination of quantities specifying hadron interaction determined from the fits of experimental elastic data in the broadest region of momentum transfers will be analyzed.