189,791 research outputs found
Neurophysiological correlates of sleep leg movements in acute spinal cord injury
No full textAbstract not availableRaffaele Ferri, Paola Proserpio, Francesco Rundo, Andrea Lanza, Katrina Sambusida, Tiziana Redaelli, Fabrizio De Carli, Lino Nobil
Caratterizzazione di due calcestruzzi UHPFRC commerciali: valutazione di proprietà meccaniche e di durabilità
No full textThis note presents the results of a research aimed at assessing and comparing the properties of two commercial Ultra-High-Performance Fiber Reinforced Concretes (UHPRFC) made with the same amount of steel fibers (2.5% vol.). Besides the basic properties at hardened state, such as compressive strength and elastic modulus, durability-related parameters are measured, such as electrical resistivity, resistance to carbonation and chloride penetration, water absorption rate and water absorption. Microstructure is also studied by means of optical and electron microscopy. The results show that, although fibers may locally increase the presence of interfacial voids in the cement paste and decrease the electrical resistivity of UHPFRC, both products exhibited an overall excellent behavior if compared to ordinary concrete
Influence of steel fibers on durability properties of UHPFRC
No full textUltra-high-performance fiber-reinforced concrete (UHPFRC) is a high-strength cementitious material whose composition can be designed to achieve given properties in the fresh and hardened state. Thanks to the low water/binder ratio (around 0.2) and to the presence of mineral additions, it is characterized by a low porosity which is often taken as a guarantee of intrinsic - almost unlimited - durability. However, the number of researches on the long-term behavior of this type of material is relatively limited, in particular with respect to the corrosion behavior of steel and to the role of steel fibers on concrete durability. This note presents the results of a research aimed at studying the influence of fibers on durability properties. Besides tests for the characterization at fresh and hardened state, durability-related parameters such as electrical resistivity, resistance to chloride penetration, absorption rate and water absorption are investigated. The results show that higher amount of fibers increased the porosity of fibers-concrete interfacial zone and therefore large fibers content negatively influences the parameters related to durability. However, the investigated parameters indicate higher performances with respect to ordinary concretes even in UHPFRC with large fiber content, except for electrical resistivity
Technical Note: Year, season, and parity effect on weaning performance of the Carmagnola Grey Rabbit breed
No full textTo evaluate the main environmental factors in the productivity of Carmagnola Grey rabbits, an endangered breed indigenous to northern Italy, data collected over 8 years were analysed. Production data on the pure closed nucleus herd of the University of Turin were used. Effects of parity, season and age of weaning on the number of rabbits born alive and weaned, litter weight and individual average weight at weaning were studied. The following average performance rates over the 8 years period were determined: 8.1 live born and 7.2 weaned kits per litter and a litter weight at weaning of 7287 g or 1024 g individual weaning weight. Year and season both had a significant effect (P < 0.001) on all the traits studied as well as weaning age (P < 0.001).Lazzaroni, C.; Biagini, D.; Redaelli, V.; Luzi, F. (2012). Technical Note: Year, season, and parity effect on weaning performance of the Carmagnola Grey Rabbit breed. World Rabbit Science. 20(1):57-60. https://doi.org/10.4995/wrs.2012.1031SWORD576020
Corrosion of reinforcement in UHPFRC ::a preliminary study including the effect of cracking
No full textUltra-High Performance Fibre-Reinforced Concrete (UHPFRC) is characterized by high compressive strength, strain-hardening behaviour in tension and very low porosity. After cracking, crack opening is controlled by the fibres. Therefore, UHPFRC is generally considered as a very durable material and is frequently used in combination with reinforcement for elements exposed to severe environmental conditions. However, scientific evidence on the long-term behaviour of reinforcement embedded in UHPFRC is limited, especially if the simultaneous presence of cracks and chemical attack is considered. This contribution presents the results of a preliminary study carried out to characterize the corrosion behaviour of reinforcement in UHPFRC. Mechanical and durability-related properties of a commercial UHPFRC were determined. Accelerated and long-term corrosion tests were initiated on cracked and uncracked prisms reinforced with carbon or stainless steel rebars.Il calcestruzzo fibrorinforzato ad altissime presta-zioni (UHPFRC) è caratterizzato da un’elevata resistenza a compressione, un comportamento a trazione incrudente e una bassa po-rosità. Inoltre, la presenza di fibre limita l’apertura delle fessure in post-fessurazione. Per queste ragioni, il calcestruzzo UHPFRC è generalmente considerato un materiale durevole ed è spesso impiegato in combinazione con armature di rinforzo per la realizzazione di elementi esposti a condizioni ambientali aggressive. Tuttavia, in letteratura sono relativamente limitati gli studi sul comportamen-to alla corrosione delle armature in UHPFRC, in particolare considerando la contemporanea presenza di fessure e agenti aggressivi come i cloruri. La memoria presenta uno studio preliminare atto alla caratterizzazione del comportamento alla corrosione delle ar-mature in UHPFRC. Si determinano le proprietà meccaniche e alcuni parametri correlati alla durabilità di un UHPFRC commercia-le, insieme allo studio del comportamento alla corrosione di armature in provini armati con acciaio al carbonio o con acciaio inossi-dabile, anche in seguito a fessurazione del calcestruzzo
The Broken Mirror: How the Contemporary Jihadist. Narrative is Re-Shaping the Classical Doctrine of Jihad
No full textVery few words in contemporary history have become as popular as the polysemous word jihad: probably the most controversial and debated concept presently associated with Islam. It is a verbal noun, both inspiring and frightening, which seems to overwhelm political debates about radical Islam. However, as always happens when technical terms become popular labels, jihad has become an overstretched word, an ideological banner, with an imprecise and broad significance, often disconnected from the classical doctrine, which the contemporary jihadist ideologists nonetheless refer to. Its doctrinal, legal, religious and moral boundaries are constantly contested both by Muslim and non-Muslim authors. Even more puzzling is the debate on the limits and regulations of jihad, and if jihad truly represents the Islamic version of Bellum justum. In other words, the current debate has transformed jihad into a sort of a ‘meta-concept’. One, however, that offers totally divergent narratives according to those who use it and which serves to foster political identities for a range of very different movements, from ‘religious nationalist’ groups to transnational, or ‘glocal’, ones. In this chapter, we will try to follow its historical evolution and its transformation from a multifarious concept to a codified set of legal doctrines to a powerful mobilizing ideology in the 20th century, up to its current transformation into a sort of universal brand, deprived nonetheless of an acknowledged copyright
World Climate Research Program Special Workshop on Climatic Effects of ozone depletion in the southern hemisphere: assessing the evidence and identifying gaps in the current knowledge
No full textA World Climate Research Programme (WCRP) Special Workshop titled the “Climatic effects of ozone depletion in the Southern Hemisphere: Assessing the evidence and identifying gaps in the current knowledge” focused on the current understanding of Southern Hemisphere (SH) ozone depletion, in particular high-latitude ozone depletion, with regards to its impacts on hemispheric climate and its role relative to greenhouse gas (GHG)–induced climate changes. The 2010 United Nations Environment Programme (UNEP)/World Meteorological Organization (WMO) Scientific Assessment of Ozone Depletion, and research published since, provided the starting point for discussion. The workshop was supported by WCRP, the National Science Foundation (NSF; United States), the National Aeronautics and Space Administration (NASA; United States), Agencia Nacional de Promoción Científica y Técnica (Argentina), and the Pontificia Universidad Católica Argentina (Argentina).Fil: Canziani, Pablo Osvaldo. Pontificia Universidad Católica Argentina ; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Oneill, Alan. National Centre For Earth Observations; Reino UnidoFil: Schofield, R.. University of Melbourne; AustraliaFil: Raphael, M.. University of California at Los Angeles; Estados UnidosFil: Marshall,G. J.. British Antarctic Survey; Reino UnidoFil: Redaelli, G.. Universita degli Studi dell'Aquila; Itali
Three-Dimensional Constitutive Model for Dry Granular Materials Under Different Flow Regimes
No full textThe numerical simulations of granular materials, in the framework of continuum mechanics, is quite challenging since the constitutive model should be capable of reproducing the transition from solid- to fluid like regimes and vice versa. In this paper a constitutive model, valid under general three dimensional evolving conditions, and capable of describing the material response under both quasi-static and dynamic regimes is presented. The model is calibrated by employing a series of true triaxial DEM numerical simulations performed on a periodic cell. The comparison between model predictions and DEM results highlights that the capability of the constitutive relationship of taking into account the dependence of the mechanical behaviour of the dry granular material on Lode angle, strain rate, void ratio and confining pressure
Microfluidic device and relative method for the generation and/or culture and/or maturation of three-dimensional cells and/or tissue constructs
No full textMPM simulations of granular column collapse with a new constitutive model for the solid-fluid transition
No full textDry granular flows are very common both in many natural phenomena (flow-like landslides) as well as in industrial processes. To model granular flows in the
framework of continuum mechanics, a key issue is the formulation of a suitable constitutive model, capable of capturing the complex rheological behaviour of the
granular material in a wide range of strain rates. In this contribution, a physically based model capable of reproducing the behaviour of granular materials in different
flow regimes is briefly summarized. Both the stress tensor and the dissipated energy are calculated as the sum of a quasi-static and a collisional contribution: the former
one is modelled by employing an elasto-plastic model incorporating the critical state
concept, whereas the latter stems from the kinetic theory of granular gases. The constitutive model has been implemented in the MPM research code Anura3D and applied to the simulation of the collapse of a dry granular column. The results show that the model can deal with the phase transition between the solid- and the fluid-like behaviour. The evolution of the state variables, the state of stress and the energy contributions is investigated in details
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