On micro-structural effects in dielectric mixtures

The paper presents numerical simulations performed on dielectric properties of two-dimensional binary composites on eleven regular space filling tessellations. First, significant contributions of different parameters, which play an important role in the electrical properties of the composite, are introduced both for designing and analyzing material mixtures. Later, influence of structural differences and intrinsic electrical properties of constituents on the composite's over all electrical properties are investigated. The structural differences are resolved by the spectral density representation approach. The numerical technique, without any {\em a-priori} assumptions, for extracting the spectral density function is also presented.Comment: 24 pages, 8 figure and 7 tables. It is submitted to IEEE Transactions on Dielectrics and Electrical Insulatio

Extracting spectral density function of a binary composite without a-priori assumption

The spectral representation separates the contributions of geometrical arrangement (topology) and intrinsic constituent properties in a composite. The aim of paper is to present a numerical algorithm based on the Monte Carlo integration and contrainted-least-squares methods to resolve the spectral density function for a given system. The numerical method is verified by comparing the results with those of Maxwell-Garnett effective permittivity expression. Later, it is applied to a well-studied rock-and-brine system to instruct its utility. The presented method yields significant microstructural information in improving our understanding how microstructure influences the macroscopic behaviour of composites without any intricate mathematics.Comment: 4 pages, 5 figures and 1 tabl

Signs of low frequency dispersions in disordered binary dielectric mixtures (50-50)

Dielectric relaxation in disordered dielectric mixtures are presented by emphasizing the interfacial polarization. The obtained results coincide with and cause confusion with those of the low frequency dispersion behavior. The considered systems are composed of two phases on two-dimensional square and triangular topological networks. We use the finite element method to calculate the effective dielectric permittivities of randomly generated structures. The dielectric relaxation phenomena together with the dielectric permittivity values at constant frequencies are investigated, and significant differences of the square and triangular topologies are observed. The frequency dependent properties of some of the generated structures are examined. We conclude that the topological disorder may lead to the normal or anomalous low frequency dispersion if the electrical properties of the phases are chosen properly, such that for ``slightly'' {\em reciprocal mixture}--when $\sigma_1\gg\sigma_2$, and $\epsilon_1<\epsilon_2$--normal, and while for ``extreme'' {\em reciprocal mixture}--when $\sigma_1\gg\sigma_2$, and $\epsilon_1\ll\epsilon_2$--anomalous low frequency dispersions are obtained. Finally, comparison with experimental data indicates that one can obtain valuable information from simulations when the material properties of the constituents are not available and of importance.Comment: 13 pages, 7 figure

Work and Heat Value of Bound Entanglement

Entanglement has recently been recognized as an energy resource which can outperform classical resources if decoherence is relatively low. Multi-atom entangled states can mutate irreversibly to so called bound entangled (BE) states under noise. Resource value of BE states in information applications has been under critical study and a few cases where they can be useful have been identified. We explore the energetic value of typical BE states. Maximal work extraction is determined in terms of ergotropy. Since the BE states are non-thermal, extracting heat from them is less obvious. We compare single and repeated interaction schemes to operationally define and harvest heat from BE states. BE and free entangled (FE) states are compared in terms of their ergotropy and maximal heat values. Distinct roles of distillability in work and heat values of FE and BE states are pointed out. Decoherence effects in dynamics of ergotropy and mutation of FE states into BE states are examined to clarify significance of the work value of BE states. Thermometry of distillability of entanglement using micromaser cavity is proposed.Comment: 22 pages, 10 figure

Comparison of methods for estimating continuous distributions of relaxation times

The nonparametric estimation of the distribution of relaxation times approach is not as frequently used in the analysis of dispersed response of dielectric or conductive materials as are other immittance data analysis methods based on parametric curve fitting techniques. Nevertheless, such distributions can yield important information about the physical processes present in measured material. In this letter, we apply two quite different numerical inversion methods to estimate the distribution of relaxation times for glassy \lila\ dielectric frequency-response data at 225 \kelvin. Both methods yield unique distributions that agree very closely with the actual exact one accurately calculated from the corrected bulk-dispersion Kohlrausch model established independently by means of parametric data fit using the corrected modulus formalism method. The obtained distributions are also greatly superior to those estimated using approximate functions equations given in the literature.Comment: 4 pages and 4 figure

Broadband Spectral Analysis of Non-Debye Dielectric Relaxation in Percolating Heterostructures

International audienc

Histopathological changes in the choroid plexus after traumatic brain injury in the rats: a histologic and immunohistochemical study

Background: Traumatic brain injury (TBI) is in part associated with the disruption of the blood-brain barrier. In this study, we analysed the histopathological changes in E-cadherin and vascular endothelial growth factor (VEGF) expression after TBI in rats.   Materials and methods: The rats were divided into two groups as the control and the trauma groups. Sprague-Dawley rats were subjected to TBI with a weight-drop device using 300 g/1 m weight-height impact. After 5 days of TBI, blood samples were taken under ketamine hydroxide anaesthesia and biochemical analyses were performed. The control and trauma groups were compared in terms of biochemical values.   Results: There was no change in glutathione (GSH) levels and blood-brain barier permeability. However, malondialdehyde (MDA) and myeloperoxidase (MPO) activity levels increased in the trauma group. In the histopathological examination, choroid plexus in the lateral ventricle, near the pia mater membrane, was removed. In the traumatic group, some of epithelial cells were hyperplasic. Some of them were peeled off the apical surface and had local degeneration.   Conclusions: In addition, we observed congestion in capillary vessels and mononuclear cell infiltration around the vessels. After TBI, the increase in VEGF levels, vascular permeability, and interaction with VEGF receptors in endothelial cells lead to oedema of the vessel wall. On the other hand, E-cadherin expression decreased in the tight-junction structures between epithelial cells and basal membrane, resulting in an increase in cerebrospinal fluid in the intervillous area

Foramen Scapulae Osseum

We determined that anomaly of foramen scapula osseum on a skeleton of left scapula which has been in Department of Anatomy in Medical Faculty of Dicle University. Incisura scapulae, just medial to the basis of the coracoid process, we observed that the superior transverse scapular ligament ossifies, resulting in a complete osseous passage which is named foramen scapula osseum. A very narrow scapular foramen can produce a complete peripheral compression syndrome of the suprascapular nerve (paresis of supraspinatus and infraspinatus muscles). That variation may an important role for determining in paresis of suprascapular nerve