Search results for " Matrix"

Comparative ultrastructure and carbohydrate composition of gastroliths from Astacidae, Cambaridae and Parastacidae freshwater crayfish (Crustacea, De…

2012

21 pages; International audience; Crustaceans have to cyclically replace their rigid exoskeleton in order to grow. Most of them harden this skeleton by a calcification process. Some decapods (land crabs, lobsters and crayfish) elaborate calcium storage structures as a reservoir of calcium ions in their stomach wall, as so-called gastroliths. For a better understanding of the cyclic elaboration of these calcium deposits, we studied the ultrastructure of gastroliths from freshwater crayfish by using a combination of microscopic and physical techniques. Because sugars are also molecules putatively involved in the elaboration process of these biomineralizations, we also determined their carbohy…

Development of Composites with a Self-Healing Function

2015

This research aimed to realize experimentally the facilevascular self-healing system in epoxy glass fibre reinforced composite. Using flexiblepolytetrafluoroethylene tubes as removable preforms, the channels were embeddedinto both neat epoxy resin and unidirectional glass-fibre reinforced epoxy laminate.Room temperature curable epoxy resin with a surfactant and an amine-basedhardener were the components of the binary healing agent. The specimens oftapered double cantilever beam geometry were subjected to Mode I fracture tests.Fracture of specimens released the healing agent from channels and triggeredself-healing process of the crack. Tested neat epoxy resin specimensdemonstrated recovery o…

Biochemical characteristics of the soluble organic matrix from the shell of three recent terebratulid brachiopod species.

2008

7 pages; International audience; To build their shells, brachiopods secrete a mixture of proteins and polysaccharides, collectively called the organic matrix. This matrix mediates the calcification process by allowing crystal nucleation followed by elongation and finally by stopping the crystal growth. Ultimately, the matrix controls the different microstructures formed. Brachiopod shells are composites with both organic and inorganic constituents intimately associated. This work represents an attempt to characterize the matrices using two combined approaches: (1) scanning electron microscopy for localization within the shell, (2) analysing extracted matrices at the molecular level to deter…

Artificial cartilage bio-matrix formed of hyaluronic acid and Mg2+-polyphosphate.

2016

Here we show that inorganic polyphosphate (polyP), a polyanionic metabolic regulator consisting of multiple phosphate residues linked by energy-rich phosphoanhydride bonds, is present in the synovial fluid. In a biomimetic approach, to enhance cartilage synthesis and regeneration, we prepared amorphous polyP microparticles with Mg2+ as counterions. The particles were characterised by X-ray diffraction (XRD), energy-dispersive X-ray (EDX) and Fourier transformed infrared spectroscopic (FTIR) analyses. Similar particles were obtained after addition of Mg2+ ions to a solution containing hyaluronic acid, as a major component of the synovial fluid, and soluble Na-polyP. The viscous paste-like ma…

Consequences of forest landscape changes on the availability of winter pastures for reindeer (Rangifer tarandus tarandus) from 1953 to 2003 in Kuusam…

2013

Calculating the implied correlation matrix for a Path Analysis model

2014

To overcome the limitations of two existing methods for calculating a Path Analysis implied correlation matrix, this paper presents an alternative method for calculating this matrix. This new method is based on a recurrence principle which is easy and quick to implement. This method is also operational regardless of the number of variables. The consequences of this result with the estimation or testing stages will be illustrated on the basis of examples.

Role of Natural Cross Linkers in Resin–Dentin Bond Durability: A Systematic Review and Meta-Analysis

2022

Background: The role of endogenous Matrix Metallo Proteinases in resin dentin bond deterioration over time has been well documented. The present study aimed to systematically review the literature; in vitro and ex vivo studies that assessed the outcomes of natural cross-linkers for immediate and long-term tensile bond strength were included. Methods: The manuscript search was carried out in six electronic databases—PubMed/MEDLINE, LILACS, SciELO, Cochrane, Web of Science and DOAJ, without publication year limits. Only manuscripts in English (including the translated articles) were selected, and the last search was performed in December 2020. The Preferred Reporting Items for Systematic Revi…

Identical fits of nonnegative matrix/tensor factorization may correspond to different extracted event-related potentials

2010

Nonnegative Matrix / Tensor factorization (NMF/NTF) have been used in the study of EEG, and the fit (explained variation) is often used to evaluate the performance of a nonnegative decomposition algorithm. However, this parameter only reveals the information derived from the mathematical model and just exhibits the reliability of the algorithms, and the property of EEG can not be reflected. If fits of two algorithms are identical, it is necessary to examine whether the desired components extracted by them are identical too. In order to verify this doubt, we performed NMF and NTF on the same dataset of an auditory event-related potentials (ERPs), and found that the identical fits of NMF and …

Germinal matrix hemorrhage-intraventricular hemorrhage: pathogenesis and outcomes

2015

Germinal matrix hemorrhage-intraventricular hemorrhage (GMH-IVH) is one of the CNS injuries affecting preterm infants occurring in about 15%-20% of subjects weighing less than 1500 g. Currently, using ultrasonography, we recognize three grades of GMH-IVH. Grade I involving the subependymal parenchyma and/or extending in less than 10% of the ventricle, grade II with intraventricular bleeding not expanding in more than 50% of the ventricle, grade III characterized by consistent (> 50%)intraventricu- lar bleeding with ventricular dilatation. A concomitant intraparenchymal lesion (IPL), due to a venous infarction (ex grade IV), can be associated with any grade of IVH, worsening the prognosis. P…

Extract Mismatch Negativity and P3a through Two-Dimensional Nonnegative Decomposition on Time-Frequency Represented Event-Related Potentials

2010

This study compares the row-wise unfolding nonnegative tensor factorization (NTF) and the standard nonnegative matrix factorization (NMF) in extracting time-frequency represented event-related potentials—mismatch negativity (MMN) and P3a from EEG under the two-dimensional decomposition The criterion to judge performance of NMF and NTF is based on psychology knowledge of MMN and P3a MMN is elicited by an oddball paradigm and may be proportionally modulated by the attention So, participants are usually instructed to ignore the stimuli However the deviant stimulus inevitably attracts some attention of the participant towards the stimuli Thus, P3a often follows MMN As a result, if P3a was large…