Postnatal development of the afferent innervation of the mammalian cochlea

The adult mammalian cochlea receives dual afferent innervation: the inner hair cells (IHCs) are innervated exclusively by type I spiral ganglion neurons (SGNs), whereas the outer hair cells (OHCs) are innervated by type II SGNs. We have characterized the reorganization and morphology of this dual afferent innervation pattern as it is established in the developing rat cochlea. Before the cochlear afferent innervation reaches a mature configuration, there is an initial mismatch, where both populations of SGNs innervate both types of sensory hair cells: during the first postnatal week in the rat cochlea, type I SGN innervation is eliminated from the OHC and type II SGN innervation is eliminated from the IHC. This reorganization occurs during the first two postnatal weeks just before the onset of hearing. Our data reveal distinct phases in the development of the afferent innervation of the organ of Corti: neurite refinement, with a formation of the outer spiral bundles innervating outer hair cells; neurite retraction and synaptic pruning to eliminate type I SGN innervation of OHCs, while retaining their supply to IHCs. Such a reorganization also makes the cochlea a model system for studying CNS synapse development, plasticity and elimination. The present article summarizes the recent progress in our understanding of the afferent innervation of the cochlea.Biomedical Reviews 2012; 23: 37-52

Postnatal development of the inner ear efferent innervation in mammals

Efferent innervation of the inner ear is extensively studied but the whole model revealing the development of efferent synapses is not clear yet. In mammals the lateral and medial olivocochlear systems are known as the source of efferent fibers. The lateral olivocochlear system innervates the ipsilateral cochlea, terminating on the dendrites beneath the inner hair cells (IHCs), the dendrites being spiral ganglion neuron compounds. The medial olivocochlear system is involved in forming synapses directly on the outer hair cells (OHCs). To reach the final targets efferent axons use the afferent fibers as a scaffold. Efferent synaptogenesis occurs just before the onset of hearing. At P0 in rats we observed synaptic-like contacts lacking typical features. At P3 the synapses were immature. At P4-P5 efferent contacts with IHCs were clearly defined. At P6-P7 the efferent terminals were larger with distinct synaptic vesicles. During maturation, at P8-P10, the number of efferent synapses at the base of the ICHs reduced alongside with a decrease in the synaptic cisternae. After P12 efferent terminals formed axodendritic synapses below IHCs and large axosomatic synapses on OHCs. The innervation of OHCs underwent two stages, i.e. transitional with simultaneous innervation of IHCs and OHCs and a final OHC-targeted innervation. These results support the idea for a waiting period of efferent innervation before its final establishment in adult organ of Corti. We also summarize the role of neurotrophic factors, specific neurotransmitter systems, their receptors and transporters for refinement of cochlear efferent innervation.Biomedical Reviews 2013; 24: 33-48

Clustering of Trading Activity in the DAX Index Options Market

A common contention is that more liquid financial contracts draw trading volume from contracts for which they are close substitutes. This paper tests this hypothesis by analyzing clustering of trading activity in DAX index options. Contracts with identical maturities cluster around particular classes of strike prices. For example, options with strikes ending on 50 are less traded then aoptions with strikes ending on 00. The degree of substitution between options with neighboring strikes depends on the strike price grid and options' characteristics. our empirical analysis finds a positive relation between clustering and substitutiability between option contracts, providing support to the initial hypothesis

Positive approximations of the inverse of fractional powers of SPD M-matrices

This study is motivated by the recent development in the fractional calculus and its applications. During last few years, several different techniques are proposed to localize the nonlocal fractional diffusion operator. They are based on transformation of the original problem to a local elliptic or pseudoparabolic problem, or to an integral representation of the solution, thus increasing the dimension of the computational domain. More recently, an alternative approach aimed at reducing the computational complexity was developed. The linear algebraic system $\cal A^\alpha \bf u=\bf f$, $0< \alpha <1$ is considered, where $\cal A$ is a properly normalized (scalded) symmetric and positive definite matrix obtained from finite element or finite difference approximation of second order elliptic problems in $\Omega\subset\mathbb{R}^d$, $d=1,2,3$. The method is based on best uniform rational approximations (BURA) of the function $t^{\beta-\alpha}$ for $0 < t \le 1$ and natural $\beta$. The maximum principles are among the major qualitative properties of linear elliptic operators/PDEs. In many studies and applications, it is important that such properties are preserved by the selected numerical solution method. In this paper we present and analyze the properties of positive approximations of $\cal A^{-\alpha}$ obtained by the BURA technique. Sufficient conditions for positiveness are proven, complemented by sharp error estimates. The theoretical results are supported by representative numerical tests

Work with motivated and gifted students in physics in RCT “Mihajlo Pupin” from Pančevo - a review of the last 15 years

Since the very beginning, Regional Center for Talents “Mihajlo Pupin” in Pančevo had a physics group. Over time, the number of classes has grown, but so did the number of students and mentors. Consequently, the achievements on national and even international competitions in physics were growing steadily. After first few years spent in experimenting different possibilities in the field of work with talented students in physics, the standard of classes has been established. Such standard, with the help of motivated students and mentors has produced a successful mechanism for preparing students for various challenges in the field of physics and beyond. This paper presents a model of working in the physics group in Regional Center for Talents “Mihajlo Pupin” in Pančevo, as well as the results our students have achieved on national and international physics and science competitions in the last 15 years of work.BPU11 : 11th International Conference of the Balkan Physical Union : Proceedings book; Aug 11 - Sep 1, 2022S14-PEHPP Physics Education, History and Philosophy of Physic

First-Principles Modeling of Oxygen-Deficient Anatase TiO2Nanoparticles

First-principles calculations of the electronic structure of reduced anatase TiO2 nanoparticles are performed using a hybrid density functional theory approach for an accurate description of charge trapping. It is found that, in the bulk and at extended surfaces, electrons introduced by oxygen vacancies delocalize but, in reduced nanoparticles, electrons preferentially localize (forming Ti3+ species) at low-coordinated sites on the surface of the particle. It is favorable for nanoparticles to be oxygen-deficient in oxygen-poor conditions with the Ti33O66 nanoparticle being significantly easier to reduce than the larger Ti151O302 nanoparticle. Since low-coordinated sites are more prevalent in smaller nanoparticles, this suggests that there is a delicate balance between the number of carriers introduced by vacancies and the number of trapped electrons

Electronic Properties of {112} and {110} Twin Boundaries in Anatase TiO2

Abstract First-principles calculations of the electronic structure and charge-trapping behavior of Σ3 {112} and Σ1 {110} twin boundaries (TBs) in anatase TiO2 are performed using an accurate hybrid density functional theory approach. The former is characterized experimentally using transmission electron microscopy (TEM) and very good agreement on the structure is found. The {110} twin has not yet been observed but TEM and scanning tuneling microscopy (STM) image simulations are presented to aid experimental identification. Holes are found to trap in a polaronic configuration at both the twin boundaries. The {112} TB presents more favorable sites for hole polaron formation at the boundary with trapping energies 0.16?0.18eV, more favorable than the bulk. The {110} TB presents hole polaron trapping sites ranging from 0.07 eV, less favorable, to 0.14 eV, more favorable, than the bulk. Neither boundary is found to favor electron trapping, indicating they are relatively benign to the performance of anatase as an n-type conductor

Ways to Reduce Water Erosion on Mountainous Slope Lands

The most important problem in the highland area is the development of technologies to reduce water erosion and improve soil fertility preservation. In order to restore degraded soils of slope lands, a number of measure is undertaken, among them planting crops across the slope and rational fertilizer treatment. To reduce erosion processes, mineral fertilizers were applied depending on the steepness of slope. High sections with the steepness of 9–10∘ received ammonium sulphate in a quantity of 60 kg/ha. Lower part of the slope with the steepness of 5–7∘ received ammonia nitrate as a nitrogen fertilizer in a quantity of 80 kg/ha, while the gentle sloping part with 2–5∘ had urea-formaldehyde fertilizer incorporated under winter tillage in a quantity of 50 kg/ha. At that, stripes were formed across the slope where tall-growing perennial herbs were planted: hill mustard (Bunias orentalis L.), silphium (Silphium perfaliatum), Eastern galega (Galeqa orientalis L.), cock’s foot grass (Dakfilis qlamerata L.). The research results have shown that thanks to fertilizers, yield of crops increases by a factor of 1.5–2, while soil losses reduced from 0.042 to 0.018 t/ha