Search results for "fiber"

FRP reinforcement for concrete structures: state-of-the-art review of application and design

2014

Fiber reinforced polymers (FRPs) are considered to be a promising alternative to steel reinforcement, especially in concrete structures subjected to an aggressive environment or to the effects of electromagnetic fields. Although attempts to develop effective reinforcement have been followed, the application of FRPs remains limited by the solution to simple structural problems that mainly appear due to the absence of design codes, significant variation in the material properties of FRP composites and limited knowledge gained by engineers as regards the application aspects of FRP composites and structural mechanics of concrete elements reinforced with FRPs. To fill the latter gap, the current…

Metabotropic glutamate receptors activate phospholipase D in astrocytes through a protein kinase C-dependent and Rho-independent pathway.

2003

Metabotropic glutamate receptors (mGluRs) are G protein-coupled receptors that mediate phospholipase D (PLD) activation in brain, but the mechanism underlying this response remains unclear. Here we used primary cultures of astrocytes as a cell model to explore the mechanism that links mGluRs to PLD. Glutamate activated both phospholipase C (PLC) and PLD with equal potency and this effect was mimicked by L-cysteinesulfinic acid, a putative neurotransmitter previously shown to activate mGluRs coupled to PLD, but not PLC, in adult brain. PLD activation by glutamate was dependent on Ca(2+) mobilization and fully blocked by both protein kinase C (PKC) inhibitors and PKC down-regulation, suggesti…

Blood Flow Restriction Exercise: Considerations of Methodology, Application, and Safety

2020

Eirāzijas bebra Castor fiber sezonālā un diennakts aktivitāte pilstētvidē - Rīgas pilsētas kanāla piemērs

2021

Pasaulē ir zināmi pētījumi par Eirāzijas bebra uzvedību dabiskos apstākļos, taču tā maz pētīta urbānā vidē, kur šķietami pastāv vairāk apdraudējumu un traucējumu. Nav skaidrs, vai bebrs, dzīvojot pilsētā, spēj nodrošināt nepieciešamo barības krājumu daudzumu ziemai. Darba mērķis ir noskaidrot bebra sezonālo un diennakts aktivitāti Rīgas pilsētas kanālā. Lai varētu konstatēt bebru ģimenes sezonālo un diennakts aktivitāti Rīgas kanāla malas koka zarā tika uzstādīta mednieku kamera. Laika posmā no 2017. līdz 2021. gadam konstatētas 598 bebra aktivitātes fotofiksācijas kamerā. Aktivitāte sākas pēc saulrieta ap plkst. 20 un ilgst līdz pat plkst. 9 no rīta. Vislielākā aktivitāte no 42 nedēļas līd…

Photoluminescence properties of point defects in Ge-doped fibers and preforms

2008

International audience; The optical properties of Ge-related point defects are often the most important parameter for the performances of silica based optical fibers. On one side their presence is often detrimental for the light transmission, on the other side some defect typologies exhibit modifications under radiation exposure thus offering the peculiar property of photosensitivity that is exploited to build technologically relevant devices such as fiber Bragg gratings.

10-keV X-ray irradiation effects on phosphorus doped fibers and preforms: electron spin resonance and optical studies

2009

Fibre fragment distribution in a single-fibre composite tension test

2001

Abstract Single fibre fragmentation tests are performed for brittle fibres with Weibull strength distribution and different surface treatments. The fragmentation process is modelled and closed-form expressions for break spacing distribution are obtained. The model accounts for the effect of finite fibre length on the initial fragmentation as well as for break interaction on the advanced fragmentation stage. It is assumed that the exclusion zone due to fibre–matrix interface failure and stress recovery in the fibre is linearly dependent on the applied load. This assumption is validated experimentally. The derived theoretical average fragment length dependence on applied load is used to deter…

Time resolved emission at 1.3 μm of a single InAs quantum dot by using a tunable fibre Bragg grating

2013

Photoluminescence and time resolved photoluminescence from single metamorphic InAs/GaAs quantum dots (QDs) emitting at 1.3 mu m have been measured by means of a novel fibre-based characterization set-up. We demonstrate that the use of a wavelength tunable fibre Bragg grating filter increases the light collection efficiency by more than one order of magnitude as compared to a conventional grating monochromator. We identified single charged exciton and neutral biexciton transitions in the framework of a random population model. The QD recombination dynamics under pulsed excitation can be understood under the weak quantum confinement potential limit and the interaction between carriers at the …

Hormone replacement therapy improves contractile function and myonuclear organization of single fibres from postmenopausal monozygotic female twin pa…

2013

Ageing is associated with a decline in muscle mass and strength leading to increased physical dependency in old age. Postmenopausal women experience a greater decline than men of similar age in parallel with the decrease in female sex steroid hormone production. We recruited six monozygous female twin pairs (55–59 years old) where only one twin pair was on hormone replacement therapy (HRT use = 7.8 ± 4.3 years) to investigate the association of HRT with the cytoplasmic volume supported by individual myonuclei (myonuclear domain (MND) size,) together with specific force at the single fibre level. HRT use was associated with a significantly smaller (∼27%; P < 0.05) mean MND size in muscle fib…

Potential combined effects of maternal smoking and coffee intake on foetal death within the Danish National Birth Cohort

2018

Background: Several studies have linked coffee intake and smoking to foetal death, but a possible interaction between both exposures remains unknown.Methods: We studied, within the Danish National Birth Cohort, the potential interaction between smoking and coffee drinking while pregnant on the risk of foetal (early and late) death. The study included 90 086 pregnant women, with information about their smoking habit and coffee intake in early pregnancy, and several potential confounding factors. Interaction was studied by calculating both the hazard ratio (HR) in Cox's regression (linear and smoothed restricted cubic spline) and the interaction contrast ratio (ICR).Results: Women who neither…