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

Quantum Superposition States: Spin Glasses and Entanglement

Spin-glass (SG) is a fascinating system that has garnered significant attention due to its intriguing properties and implications for various research fields. One of the key characteristics of spin glasses is that they contain random disorder, which leads to many possible states of the system occurring with very close probabilities. We explore the concept of spin-glass superposition states (SSs), which are equiprobable SSs of possible electronic configurations. Using the Edward-Anderson (EA) type SG order parameter $q_{EA}$ and magnetization, we demonstrate that these SSs can be classified based on their contribution to distinguishing magnetic order (disorder), such as SG, (anti)ferromagnetic (FM), and paramagnetic (PM) phases. We also generalize these superposition states based on the system size and investigate the entanglement of these phase-based SSs using the negativity measure. We show that the SG order parameter can be utilized to determine the entanglement of magnetically ordered (disordered) phases, or vice versa, with negativity signifying magnetic order. Our findings provide further insight into the nature of quantum SSs and their relevance to SGs and quantum magnets. They have implications for various fields, including condensed matter physics, where SGs are a prototypical example of disordered systems. They are also relevant for other fields, such as neural networks, optimization problems, and information storage, where complex systems with random disorder behavior are greatly interested. Overall, our study provides a deeper understanding of the behavior of SGs and the nature of quantum SSs, with potential applications in various fields.Comment: 8 pages, 5 figure

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

Online Fault Classification in HPC Systems through Machine Learning

As High-Performance Computing (HPC) systems strive towards the exascale goal, studies suggest that they will experience excessive failure rates. For this reason, detecting and classifying faults in HPC systems as they occur and initiating corrective actions before they can transform into failures will be essential for continued operation. In this paper, we propose a fault classification method for HPC systems based on machine learning that has been designed specifically to operate with live streamed data. We cast the problem and its solution within realistic operating constraints of online use. Our results show that almost perfect classification accuracy can be reached for different fault types with low computational overhead and minimal delay. We have based our study on a local dataset, which we make publicly available, that was acquired by injecting faults to an in-house experimental HPC system.Comment: Accepted for publication at the Euro-Par 2019 conferenc

Neuroprotective effects of Potentilla fulgens on spinal cord injury in rats: an immunohistochemical analysis

Background: This examination was performed to research the advantage of the antioxidant impact of Potentilla fulgens on spinal cord injury (SCI) in rats.  Materials and methods: In the SCI model of this examination, the tolerably serious lesion was performed at the L1–L2 spinal segmental level. SCI animals were given P. fulgens 400 mg/kg/day, intraperitoneally. At 7 days post-lesion, exploratory rats were executed after intraperitoneal administration 7 ketamine HCL (0.15 mL/100 g body weight). Spinal cord specimens were taken for histological examination or assurance of malondialdehyde (MDA) and glutathione (GSH) levels and myelope- roxidase (MPO) action. SCI caused a remarkable decline in spinal cord GSH content, trailed by noteworthy increments in MDA levels and MPO action.  Results: Degenerative changes in some multipolar and bipolar nerve cells and pyknotic changes in the nuclei of glial cells were likewise noticed. Remarkable development was seen in cells and vascular structures of P. fulgens treated groups when contrasted with untreated groups.  Conclusions: Potentilla fulgens application may influence angiogenetic impro- vement in vein endothelial cells, reduce inflammatory cell aggregation by influ- encing cytokine system and may make apoptotic nerve cells and neuroprotective component in glial cells

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

Numerical calculations of effective elastic properties of two cellular structures

Young's moduli of regular two-dimensional truss-like and eye-shape-like structures are simulated by using the finite element method. The structures are the idealizations of soft polymeric materials used in the electret applications. In the simulations size of the representative smallest units are varied, which changes the dimensions of the cell-walls in the structures. A power-law expression with a quadratic as the exponential term is proposed for the effective Young's moduli of the systems as a function of the solid volume fraction. The data is divided into three regions with respect to the volume fraction; low, intermediate and high concentrations. The parameters of the proposed power-law expression in each region are later represented as a function of the structural parameters, unit-cell dimensions. The presented expression can be used to predict structure/property relationship in materials with similar cellular structures. It is observed that the structures with volume fractions of solid higher than 0.15 exhibit the importance of the cell-wall thickness contribution in the elastic properties. The cell-wall thickness is the most significant factor to predict the effective Young's modulus of regular cellular structures at high volume fractions of solid. At lower concentrations of solid, eye-like structure yields lower Young's modulus than the truss-like structure with the similar anisotropy. Comparison of the numerical results with those of experimental data of poly(propylene) show good aggreement regarding the influence of cell-wall thickness on elastic properties of thin cellular films.Comment: 7 figures and 2 table

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

International audienc

Splenic artery angiography: clinical classification of origin and branching variations of splenic artery by multi-detector computed tomography angiography method

Background: The splenic artery (SA) variations are rarely reported in the literature. Knowledge of the range of the SA and other arterial anomalies and their specific frequencies is very important ever for every visceral surgeon as well as for treatment of gastrointestinal bleeding, organ transplantation, transarterial chemoembolisation of neoplasm, infusion therapy, therapeutic arterial ligation, iatrogenic injuries. At the literature, there are more studies on the coeliac trunk, superior mesenteric artery and hepatic artery variations, but studies on the SA variations are uncommon. The studies on the SA variations are mostly in the form of case reports, but there are not many studies with large population on this issue. The purpose of this study was to evaluate the SA alone and to determine the variations determined separately from the other arteries. Accurate awareness of all the possible anatomic variations is crucial in the upper abdomen surgery. Materials and methods: Seven hundred fifty patients undergoing multi-detector computed tomography angiography between 2015 and 2017 were retrospectively evaluated for the SA variations. We created a new classification system to determine anatomic variations of the SA. Results: Twenty-three different types were identified related to anatomic variations in the origin and branching pattern of the SA. While 596 (79.47%) patients had standard SA anatomy, 154 (20.53%) patients had variant SA anatomy. Conclusions: The SA has quite different variation types and the practical context of the issue is of primary importance in surgery, gastroenterology, oncology and radiology. Liver and pancreas transplantation, splenectomy, embolisation of tumours of the abdominal organs, as well as other numerous diagnostic and therapeutic procedures, require detailed anatomical knowledg

Recurrence of atretic parietal cephalocele in adult: a case report and review of literature

Common presentation of atretic parietal cephalocele is mostly seen in infants and young children. It is a palpable midline parietal soft tissue mass which is thought to represent involuted true cephalocele (meningocele or encephalocele) connected to dura mater via a fibrous stalk. Atretic parietal cephalocele is associated with increased incidence of intracranial anomalies.. Parietal cephaloceles comprise about 1% of all cerebrospinal congenital malformations and 10% of cephaloceles. We report here the case of an atretic parietal cephalocele with no associated brain malformations in adult