515 research outputs found
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
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
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
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
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 , and
--normal, and while for ``extreme'' {\em reciprocal
mixture}--when , and --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
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
Histopathologic and immunohistochemical investigations of dental abscess formed in maxillofacial area
Background: An abscess is a pocket of pus that forms around the root of an infected tooth. In this study, we aimed to investigate the extracellular matrix proteases ADAMTS1, ADAMTS4, osteonectin, and osteopontin expressions in abscess fluid cells in jaws after implantation and prosthesis operation. Materials and methods: In this clinical study, abscess fluids belonging to 17 patients who applied to the Department of Oral and Maxillofacial Surgery were examined histopathologically and immunohistochemically. In the histopathological examination of the abscess fluid, separation of chromatin bridges in the nuclei of neutrophil cells, pyknosis and apoptotic changes in the nucleus, degenerative change in the cytoplasm, and occasional vacuolar structures were observed. Results: The positive reaction of ADAMTS1 was observed in fibroblast cells, plasma cells, and macrophage cells. The positive reaction of ADAMTS4 was observed in fibroblast cells, osteoclast cells, and some apoptotic leukocyte cells. Osteopontin expression in osteoclastic cells and polymorphonuclear cells was defined as positive. Osteonectin expression was positive in polymorphonuclear leukocytes and hypertrophic fibroblast cells. Conclusions: ADAMTS1 and ADAMTS4 may induce bone destruction with its distinctive property in alveolar bone resorption, which promotes the activation of osteoclasts, which can accelerate the destruction of the extracellular matrix in the acute phase. Furthermore, osteoclastic activity increased with the increase of osteonectin and osteopontin protein expression due to inflammation in the abscess cases
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