1,809 research outputs found

    Harnack inequality and regularity for degenerate quasilinear elliptic equations

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    We prove Harnack inequality and local regularity results for weak solutions of a quasilinear degenerate equation in divergence form under natural growth conditions. The degeneracy is given by a suitable power of a strong A∞A_\infty weight. Regularity results are achieved under minimal assumptions on the coefficients and, as an application, we prove C1,αC^{1,\alpha} local estimates for solutions of a degenerate equation in non divergence form

    Microstructure and chemical composition of Roman orichalcum coins emitted after the monetary reform of Augustus (23 B.C.)

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    A collection of ancient Roman orichalcum coins, i.e., a copper-zinc alloy, minted under the reigns from Caesar to Domitianus, have been characterised using scanning electron microscopy (SEM-EDS) and electron microprobe analysis (EMPA). We studied, for the first time, coins emitted by Romans after the reforms of Augustus (23 B.C.) and Nero (63-64 A.D). These coins, consisting of asses, sestertii, dupondii and semisses, were analysed using non- and invasive analyses, aiming to explore microstructure, corrosive process and to acquire quantitative chemical analysis. The results revealed that the coins are characterized by porous external layers, which are affected by dezincification and decuprification processes. As pictured by the X-ray maps, the elemental distribution of Cu and Zn shows patterns of depletion that in some cases penetrate in deep up to 1 mm. The composition of the un-corroded nucleus is a Cu-Zn alloy containing up to 30% of Zn, typical of coins produced via cementation process

    CleAir monitoring system for particulate matter. A case in the Napoleonic Museum in Rome

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    Monitoring the air particulate concentration both outdoors and indoors is becoming a more relevant issue in the past few decades. An innovative, fully automatic, monitoring system called CleAir is presented. Such a system wants to go beyond the traditional technique (gravimetric analysis), allowing for a double monitoring approach: the traditional gravimetric analysis as well as the optical spectroscopic analysis of the scattering on the same filters in steady-state conditions. The experimental data are interpreted in terms of light percolation through highly scattering matter by means of the stretched exponential evolution. CleAir has been applied to investigate the daily distribution of particulate matter within the Napoleonic Museum in Rome as a test case

    Activated Tryptophan-Kynurenine metabolic system in the human brain is associated with learned fear

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    Fear is widely recognized as a defensive emotion that has developed as a consequence of its adaptive function in protecting the entire animal kingdom from danger, ensuring the survival (Bouton, 2002; Milad and Quirk, 2002). Although fear associated with specific stimuli is an innate emotion (e.g., a loud noise triggering fear in infants, fear of potential predators), it can also be acquired rapidly and permanently to enable an appropriate and adaptive response to new or unpredictable environmental situations (LeDoux, 2000; Beckers et al., 2013)

    Edge channel mixing induced by potential steps in an integer quantum Hall system

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    We investigate the coherent mixing of co-propagating edge channels in a quantum Hall bar produced by step potentials. In the case of two edge channels it is found that, although a single step induces only a few percent mixing, a series of steps could yield 50% mixing. In addition, a strong mixing is found when the potential height of a single step allows a different number of edge channels on the two sides of the step. Charge density probability has been also calculated even for the case where the step is smoothened.Comment: final version: 7 pages, 6 figure

    Neuropharmacological Modulation of N-methyl-D-aspartate, Noradrenaline and Endocannabinoid Receptors in Fear Extinction Learning: Synaptic Transmission and Plasticity

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    Learning to recognize and respond to potential threats is crucial for survival. Pavlovian threat conditioning represents a key paradigm for investigating the neurobiological mechanisms of fear learning. In this review, we address the role of specific neuropharmacological adjuvants that act on neurochemical synaptic transmission, as well as on brain plasticity processes implicated in fear memory. We focus on novel neuropharmacological manipulations targeting glutamatergic, noradrenergic, and endocannabinoid systems, and address how the modulation of these neurobiological systems affects fear extinction learning in humans. We show that the administration of N-methyl-D-aspartate (NMDA) agonists and modulation of the endocannabinoid system by fatty acid amide hydrolase (FAAH) inhibition can boost extinction learning through the stabilization and regulation of the receptor concentration. On the other hand, elevated noradrenaline levels dynamically modulate fear learning, hindering long-term extinction processes. These pharmacological interventions could provide novel targeted treatments and prevention strategies for fear-based and anxiety-related disorders

    Lifetimes of b-flavoured hadrons

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    I discuss the heavy quark expansion for the inclusive widths of heavy-light hadrons, which predicts quite well the experimental ratios of B_q meson lifetimes. As for Λb\Lambda_b, current determinations of O(mb−3){\cal O}(m_b^{-3}) contribution to τ(Λb)\tau(\Lambda_b) do not allow to explain the small measured value of τ(Λb)/τ(Bd)\tau(\Lambda_b)/\tau(B_d). As a final topic, I discuss the implications of the measurement of the B_c lifetime.Comment: LaTex, 4 pages, 1 figure. Talk given at the "U.K. Phenomenology Workshop on Heavy Flavours and CP violation" Durham, 17-22 Sep. 2000 (Mixing and Lifetimes Working Group

    Preliminary realization of an electric-powered hydraulic pump system for a waste compactor truck and a techno-economic analysis

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    Most industrial trucks are equipped with hydraulic systems designed for specic operations, for which the required power is supplied by the internal combustion engine (ICE). The largest share of the power consumption is required by the hydraulic system during idling operations, and, consequently, the current literature focuses on energy saving strategies for the hydraulic system rather than making the vehicle traction more efficient. This study presents the preliminary realization of an electric-powered hydraulic pump system (e-HPS) that drives the lifting of the dumpster and the garbage compaction in a waste compactor truck, rather than traditional ICE-driven hydraulic pump systems (ICE-HPSs). The different components of the e-HPS are described and the battery pack was modelled using the kinetic battery model. The end-of-life of the battery pack was determined to assess the economic feasibility of the proposed e-HPS for the truck lifespan, using numerical simulations. The aim was twofold: To provide an implementation method to retrofit the e-HPS to a conventional waste compactor truck and to assess its economic feasibility, investigating fuel savings during the use phase and the consequent reduction of CO2 emissions. Results show that the total lifespan cost saving achieved a value of 65,000. Furthermore, total CO2 emissions for the e-HPS were about 80% lower than those of the ICE-HPS, highlighting that the e-HPS can provide significant environmental benefits in an urban context

    The importance of post-mortem computed tomography (PMCT) as a complementary diagnostic technique to traditional autopsy in a case of asphyxia related-death

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    Although asphyxia related-death is a common occurrence in forensic setting, traditional autopsy with neck dissection is not always sufficient to gain information about potential injuries of the deep structures of the neck. In this case a 40 years-old white female was found unresponsive on the floor of her living room, in supine position with a widespread brownish area on her neck. A preliminary PMCT examination showed a fracture line within the hyoid bone. This finding was confirmed by the autopsy, which revealed soft tissue’s haemorrhage of the sternocleidomastoid and sternohyoid muscles and a fracture of the right horn of the hyoid bone. A 3D reconstruction of the event showed the aggressor standing behind the victim while holding his arm around her neck. Our study demonstrates that, PMCT represent an effective aid to traditional examination techniques in order to visualize fractures. The former always requires to be associated with autoptic examination
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