Search results for "plastic"

Modulation of neuronal plasticity by events produced in adolescence: role of environmental enrichment and cannabis consumption

2017

Según Linda Spear, la adolescencia es un período de transición entre la juventud y la madurez, caracterizado por la toma de riesgos a nivel de conductual, pero también por un aumento de las hormonas sexuales (Spear, 2000). Además, hay una transformación importante en el cerebro adolescente, particularmente en el hipocampo, la amígdala y la corteza prefrontal. En esas zonas, así como en otras, durante este período se produce una remodelado dendrítico, una intensa mielinización y un fortalecimiento de la neurocircuitería. Las monoaminas dopamina, serotonina y melatonina participan en estos procesos y son cruciales en el comportamiento del adolescente (Arain et al., 2013). Además, en este perí…

von Hippel-Lindau Protein-Mediated Repression of Tumor Necrosis Factor Alpha Translation Revealed through Use of cDNA Arrays

2003

Based on evidence that the von Hippel-Lindau (VHL) tumor suppressor protein is associated with polysomes and interacts with translation regulatory factors, we set out to investigate the potential influence of pVHL on protein translation. To this end, renal cell carcinoma (RCC) cells that either lacked pVHL or expressed pVHL through stable transfection were used to prepare RNA from cytosolic (unbound) and polysome-bound fractions. Hybridization of cDNA arrays using RNA from each fraction revealed a subset of transcripts whose abundance in polysomes decreased when pVHL function was restored. The tumor necrosis factor alpha (TNF-alpha) mRNA was identified as one of the transcripts that prefere…

Strain gradient plasticity, strengthening effects and plastic limit analysis

2010

Abstract Within the framework of isotropic strain gradient plasticity, a rate-independent constitutive model exhibiting size dependent hardening is formulated and discussed with particular concern to its strengthening behavior. The latter is modelled as a (fictitious) isotropic hardening featured by a potential which is a positively degree-one homogeneous function of the effective plastic strain and its gradient. This potential leads to a strengthening law in which the strengthening stress, i.e. the increase of the plastically undeformed material initial yield stress, is related to the effective plastic strain through a second order PDE and related higher order boundary conditions. The plas…

Effect of electron beam irradiation and plastic deformation on molar mass of medical grade ultra-high molecular weight polyethylene

2010

Badano wpływ sterylizacji metodą napromieniania strumieniem elektronów oraz deformacji plastycznej (zgniatania, rys. 1) polietylenu ultrawielkocząsteczkowego (UHMW-PE), stosowanego do wytwarzania panewek endoprotez stawu biodrowego, na masę molową polimeru. Stwierdzono, że sterylizacja wpływa na utleniającą destrukcję makrocząsteczek polimeru, której stopień zależy od użytej dawki promieniowania (zmniejszenie masy molowej masowo średniej). Procesowi temu towarzyszy sieciowanie makrocząsteczek (wzrost udziału frakcji nierozpuszczalnej). Z kolei sama deformacja plastyczna wydaje się nie mieć wyraźnego wpływu na proces degradacji. Tymczasem łączne zastosowanie obydwu czynników zewnętrznych pro…

Synthesis of Ultra-High-Molecular-Weight Polyethylene

1984

The catalytic activity of organometallic Ti-Al complexes with donor ligands in the low-pressure polymerization of ethylene was studied. These complexes were obtained by the reaction of ethylaluminium compounds like AlEt2Cl or Al2Et3Cl3 and titanium compound of the type Ti(OR)nCl4-n (where: R = C2—C10 alkyl, C6H5, C6H4X; X — m-CH3, p-CH3, m-OCH3, p-OCH3, m-Cl, p-Cl, p-Br; n = 1—4). The optimum conditions for the synthesis of these compounds, as well as their physico-chemical properties were studied by means of EPR and polarographic methods. The effect of the type and number of OR ligands in a catalytic system on the yield of polyethylene and on its properties was examined. Ti-Al catalysts wi…

Elastic Deformation of Dispersely Failing Unidirectionally Reinforced Composites

2003

A phenomenological model is proposed for describing the elastic deformation of a unidirectionally reinforced composite capable of accumulating scattered microdamages during its loading. The composite is considered as a homogeneous transversely isotropic solid. Its damaged state at every point is characterized by a centrally symmetric scalar function on the unit sphere (the damage function), which is used to account for variations in the elastic properties of the material during its deformation. The damage itself depends on the history of some equivalent strain, for which four simplified variants are suggested. The relation between strains and stresses is defined in a differential form. Depe…

Deformation of Polypropylene Foam Neopolen® P in Compression

2004

Neopolen® P is a two-phase cellular composite foam material produced by BASF AG, Germany. In most of the practical applications, Neopolen® P works under a range of small and compressive deformations. Therefore it is necessary to determine the moduli in compression and compressive strength in the most effective way for a wide range of foam densities: 22≤ρ84≤kg/m3. Several experimental methods of different precision for deformation properties of Neopolen® P were compared. The direct measurements performed by a universal testing machine were used for the main part of the experiments. They were compared with results obtained by a more precise and time-consuming method, using an inductive exten…

Regulation of mRNA transport, localization and translation in the nervous system of mammals (Review).

2014

Post-transcriptional control of mRNA trafficking and metabolism plays a critical role in the actualization and fine tuning of the genetic program of cells, both in development and in differentiated tissues. Cis-acting signals, responsible for post-transcriptional regulation, reside in the RNA message itself, usually in untranslated regions, 5' or 3' to the coding sequence, and are recognized by trans-acting factors: RNA-binding proteins (RBPs) and/or non-coding RNAs (ncRNAs). ncRNAs bind short mRNA sequences usually present in the 3'-untranslated (3'-UTR) region of their target messages. RBPs recognize specific nucleotide sequences and/or secondary/tertiary structures. Most RBPs assemble on…

Re:Altaf Mangera, Jacob M. Patterson, Christopher R. Chapple. A systematic review of graft augmentation urethroplasty techniques for the treatment of…

2011

Human Papilloma Virus-Dependent HMGA1 Expression Is a Relevant Step in Cervical Carcinogenesis

2008

HMGA1 is a member of a small family of architectural transcription factors involved in the coordinate assembly of multiprotein complexes referred to as enhanceosomes. In addition to their role in cell proliferation, differentiation, and development, high-mobility group proteins of the A type (HMGA) family members behave as transforming protoncogenes either in vitro or in animal models. Recent reports indicated that HMGA1 might counteract p53 pathway and provided an interesting hint on the mechanisms determining HMGA's transforming potential. HMGA1 expression is deregulated in a very large array of human tumors, including cervical cancer, but very limited information is available on the mole…