Search results for "Matrix"
showing 10 items of 3205 documents
The influence of matrix rheology and vorticity on fabric development of populations of rigid objects during plane strain deformation
2002
Abstract The influence of vorticity and rheology of matrix material on the development of shape-preferred orientation (SPO) of populations of rigid objects was experimentally studied. Experiments in plane strain monoclinic flow were performed to model the fabric development of two populations of rectangular rigid objects with object aspect ratios (Rob) 2 and 3. The density of the rigid object populations was 14% of the total area. Objects were dispersed in a Newtonian and a non-Newtonian, power law matrix material with a power law exponent n of 1.2. The kinematic vorticity number (Wn) of the plane strain monoclinic flow was 1, 0.8 and 0.6 with finite simple shear strain of 4.6, 3.0 and 0.9,…
Narrare la generatività familiare
2018
L’Autore propone una breve riflessione sulla formazione del sistema emozionale del soggetto; tema pedagogicamente rilevante perché permette di comprendere la prima alfabetizzazione emotiva che avviene in famiglia. Aiuta anche ad esplorare le «matrici transpersonali del sé»; e a pervenire all’intelligenza di un aspetto specifico secondo il quale ogni persona è un erede: grazie alla famiglia infatti ogni soggetto riceve come prima eredità una mente. The author proposes a short reflection on the training of the emotional system of the subject; that is a pedagogically relevant theme because it allows to comprehend the first emotional literacy that happens in family. It also helps to explore the…
Links and Bifurcations in Nonsingular Morse–Smale Systems
1997
Wada's theorem classifies the set of periodic orbits in NMS systems on S3 as links, that can be written in terms of six operations. This characterization allows us to study the topological restrictions that links require to suffer a given codimension one bifurcation. Moreover, these results are reproduced in the case of NMS systems with rotational symmetries, introducing new geometrical tools.
Matrix metalloproteinases 2 and 9, and extracellular matrix in Kaposi's sarcoma
2010
Matrix metalloproteinases (MMPs) are associated with Kaposi's sarcoma (KS) tumorigenesis and may contribute to the mechanism of KS invasive growth. To date, only a few MMPs have been studied in KS lesions, and exactly which MMPs are involved in KS development and progression remains unanswered. However, MMPs 2 and 9 have been associated with different phases of angiogenesis, but their role in the proteolytic modification of the extracellular matrix has not been investigated. The results of this study confirm that MMPs, specifically MMP-2 and MMP-9, can contribute to angiogenesis by disrupting the vessel basement membrane and other extracellular matrix barriers, and enabling endothelial cell…
Approximation of W1, Sobolev homeomorphism by diffeomorphisms and the signs of the Jacobian
2018
Abstract Let Ω ⊂ R n , n ≥ 4 , be a domain and 1 ≤ p [ n / 2 ] , where [ a ] stands for the integer part of a. We construct a homeomorphism f ∈ W 1 , p ( ( − 1 , 1 ) n , R n ) such that J f = det D f > 0 on a set of positive measure and J f 0 on a set of positive measure. It follows that there are no diffeomorphisms (or piecewise affine homeomorphisms) f k such that f k → f in W 1 , p .
Mappings of finite distortion: Monotonicity and continuity
2001
We study mappings f = ( f1, ..., fn) : Ω → Rn in the Sobolev space W loc (Ω,R n), where Ω is a connected, open subset of Rn with n ≥ 2. Thus, for almost every x ∈ Ω, we can speak of the linear transformation D f(x) : Rn → Rn, called differential of f at x. Its norm is defined by |D f(x)| = sup{|D f(x)h| : h ∈ Sn−1}. We shall often identify D f(x) with its matrix, and denote by J(x, f ) = det D f(x) the Jacobian determinant. Thus, using the language of differential forms, we can write
Effect of sodium bicarbonate treatment on mechanical properties of flax-reinforced epoxy composite materials
2017
This paper deals with the evaluation of the effect of an eco-friendly and cost-effective surface treatment based on the use of sodium bicarbonate on the mechanical properties of flax-reinforced epoxy composites. To this aim, unidirectional fabrics were soaked for five days in 5 and 10% in weight of sodium bicarbonate solution at 25℃. Quasi-static and dynamic mechanical tests were performed and the fracture surfaces of the composites were analyzed through scanning electron microscopy. Results evidenced that this treatment improves the fiber–matrix adhesion thus increasing the performances of the composites. Treating the fabrics with 10% w/w of bicarbonate solution leads to improvements of ∼…
Synthesis and degradation of type IV collagen in rat skeletal muscle during immobilization in shortened and lengthened positions
2003
Aim: Type IV collagen is a major protein in basement membranes surrounding and supporting skeletal muscle cells. In the present study, we tested the hypotheses that immobilization down-regulates synthesis and up-regulates degradation of type IV collagen in skeletal muscle. Methods: mRNA level and concentration of type IV collagen as well as mRNA levels and activities of proteins involved in its degradation were analysed from soleus (SOL), gastrocnemius (GAS) and extensor digitorum longus muscles after immobilization in shortened and lengthened positions for 1, 3 and 7 days. Results: Following immobilization, type IV collagen mRNA level was decreased in SOL and GAS suggesting down-regulat…
Determination of organophosphate flame retardants in soil and fish using ultrasound-assisted extraction, solid-phase clean-up, and liquid chromatogra…
2017
A solid–liquid extraction method in combination with high‐performance liquid chromatography and tandem mass spectrometry was developed and optimized for extraction and analysis of organophosphorus flame retardants in soil and fish. Methanol was chosen as the optimum extraction solvent, not only in terms of extraction efficiency, but also for its broader analyte coverage. The subsequent clean‐up by solid‐phase extraction is required to eliminate matrix coextractives and reduce matrix effects. Recoveries of the optimized method were 50–121% for soil and 47–123% for biota, both with high precision (RSDs <12% in soil and <23% in biota). The method limits of detection ranged from 0.06 to 0.20 ng…
A statistical design of experiments for optimizing the MALDI-TOF-MS sample preparation of polymers. An application in the assessment of the thermo-me…
2011
[EN] The sample preparation procedure for MALDI-TOF MS of polymers is addressed in this study by the application of a statistical Design of Experiments (DoE). Industrial poly (ethylene terephthalate) (PET) was chosen as model polymer. Different experimental settings (levels) for matrixes, analyte/matrix proportions and concentrations of cationization agent were considered. The quality parameters used for the analysis were signal-to-noise ratio and resolution. A closer inspection of the statistical results provided the study not only with the best combination of factors for the MALDI sample preparation, but also with a better understanding of the influence of the different factors, individua…