Spatiotemporal Properties of Sub‐Rayleigh and Supershear Ruptures Inferred From Full‐Field Dynamic Imaging of Laboratory Experiments

Many earthquakes propagate at sub‐Rayleigh speeds. Earthquakes propagating at supershear speeds, though less common, are by far more destructive. Hence, it is important to quantify the motion characteristics associated with both types of earthquake ruptures. Here we report on the spatiotemporal properties of dynamic ruptures measured in our laboratory experiments using the dynamic digital image correlation technique. Earthquakes are mimicked by the frictional rupture propagating along the interface of two Homalite plates. Digital images of the propagating ruptures are captured by an ultrahigh‐speed camera and processed with digital image correlation in order to produce sequences of evolving displacement and velocity maps. Our measurements reveal the full‐field structure of the velocity components, bridge the gap between previous spatially sparse velocimeter measurements available only at two to three locations, and enable us to quantify the attenuation patterns away from the interface

Recent Milestones in Unraveling the Full-Field Structure of Dynamic Shear Cracks and Fault Ruptures in Real-Time: From Photoelasticity to Ultrahigh-Speed Digital Image Correlation

The last few decades have seen great achievements in dynamic fracture mechanics. Yet, it was not possible to experimentally quantify the full-field behavior of dynamic fractures, until very recently. Here, we review our recent work on the full-field quantification of the temporal evolution of dynamic shear ruptures. Our newly developed approach based on digital image correlation combined with ultrahigh-speed photography has revolutionized the capabilities of measuring highly transient phenomena and enabled addressing key ques- tions of rupture dynamics. Recent milestones include the visualization of the complete displacement, particle velocity, strain, stress and strain rate fields near growing ruptures, capturing the evolution of dynamic friction during individual rupture growth, and the detailed study of rupture speed limits. For example, dynamic friction has been the big- gest unknown controlling how frictional ruptures develop but it has been impossible, until now, to measure dynamic friction during spontaneous rupture propagation and to understand its dependence on other quantities. Our recent measurements allow, by simul- taneously tracking tractions and sliding speeds on the rupturing interface, to disentangle its complex dependence on the slip, slip velocity, and on their history. In another application, we have uncovered new phenomena that could not be detected with previous methods, such as the formation of pressure shock fronts associated with “supersonic” propagation of shear ruptures in viscoelastic materials where the wave speeds are shown to depend strongly on the strain rate

A Possible Exit Strategy from the ‘Halloumi Aff air’: How to Solve Problems with CETA Ratification

This article explores the importance of geographical indications within the new trade policy of the European Union, using the example of the CETA and the dispute over Cypriot halloumi cheese. The authors point out that geographical indications occupy an important place within the European Commission’s negotiating strategy primarily because of their signifi cance for the EU economy. In negotiations with third countries, such as Canada, a crucial problem is the diff erent approaches to the protection of typical regional products. Th erefore, the Union is trying to transfer its internal solutions to the international level. Th e detail of regulations, combined with the mixed nature of new trade agreements, makes trade policy vulnerable to blackmail by individual EU Member States. According to the authors, a reasonable solution to this problem – which was highlighted by Cyprus’s veto of the CETA – is to rely on the treaty provisions and the judgements of the Court of Justice of the EU. Th ese indicate the exclusive competence of the EU in this area and impose an obligation on EU Member States to cooperate sincerely

Determination of inorganic phosphorus in serum: Evaluation of three methods applied to the Technicon RA-1000 analyzer

We have evaluated three analytical methods for determining inorganic phosphorus in serum applied to the Technicon RA-I000 analyzer: a fully enzymatic colorimetric method based on the specific system purine nucleoside phosphorylase/xanthine oxidase coupled to an indicator colorimetric reaction similar to the Trinder reaction; a chemical method involving the direct UV measurement of the phosphomolybdate complex; and a chemical method with reduction of the phosphomolybdate complex to molybdenum blue. Experiments were performed to assess within-run and between-day precision, linearity, interference and correlation. The best performance characteristics were shown by the enzymatic colorimetric method and the phosphomolybdate UV method

Radical Artificial Intelligence: A Postmodern Approach

The dynamic response of end-clamped monolithic beams and sandwich beams has been measured by loading the beams at mid-span using metal foam projectiles. The AISI 304 stainless-steel sandwich beams comprise two identical face sheets and either prismatic Y-frame or corrugated cores. The resistance to shock loading is quantified by the permanent transverse deflection at mid-span of the beams as a function of projectile momentum. The prismatic cores are aligned either longitudinally along the beam length or transversely. It is found that the sandwich beams with a longitudinal core orientation have a higher shock resistance than the monolithic beams of equal mass. In contrast, the performance of the sandwich beams with a transverse core orientation is very similar to that of the monolithic beams. Three-dimensional finite element (FE) simulations are in good agreement with the measured responses. The FE calculations indicate that strain concentrations in the sandwich beams occur at joints within the cores and between the core and face sheets; the level of maximum strain is similar for the Y-frame and corrugated core beams for a given value of projectile momentum. The experimental and FE results taken together reveal that Y-frame and corrugated core sandwich beams of equal mass have similar dynamic performances in terms of rear-face deflection, degree of core compression and level of strain within the beam

Modulation of human corticospinal excitability by paired associative stimulation in patients with amyotrophic lateral sclerosis and effects of Riluzole

BACKGROUND Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that causes an impairment in both the upper and lower motor neurons. The recent description of numerous non-motor signs points to an involvement of the neocortex networks that is more complex than was previously believed. Paired associative stimulation (PAS), a combination of transcranial magnetic stimulation (TMS) and peripheral nerve stimulation, can enhance motor output in the contralateral hand through an NMDA-mediated sensorimotor mechanism. OBJECTIVE To describe the effects of PAS on ALS patients before and after Riluzole intake compared with healthy subjects. METHODS PAS was used to detect differences between 24 newly-diagnosed ALS patients and 25 age-matched healthy controls. MEP amplitude from the abductor pollicis brevis was considered before PAS, immediately after (T0) and after 10 (T10), 20 (T20), 30 (T30) and 60 (T60) minutes. Statistical significance was calculated using RM-ANOVA. RESULTS In healthy controls, PAS significantly increased MEP amplitude at T10, T20 and T30 (p < 0.05). In ALS patients, a significant increase in MEP amplitude was also observed after 60 min (p < 0.05), thus demonstrating NMDA-mediated enhanced facilitatory plasticity. After two weeks of riluzole intake, no MEP amplitude increase was evident after PAS at any time point. In three monomelic-onset ALS patients, sensorimotor facilitation was evident only in the hemisphere corresponding to the affected side and appeared in the opposite hemisphere when the patients manifested contralateral symptoms. CONCLUSIONS PAS may be considered a useful tool when investigating NMDA-mediated neocortical networks in ALS patients and the modulation of such networks after anti-glutamatergic drug intake

Understanding dynamic friction through spontaneously evolving laboratory earthquakes

Friction plays a key role in how ruptures unzip faults in the Earth’s crust and release waves that cause destructive shaking. Yet dynamic friction evolution is one of the biggest uncertainties in earthquake science. Here we report on novel measurements of evolving local friction during spontaneously developing mini-earthquakes in the laboratory, enabled by our ultrahigh speed full-field imaging technique. The technique captures the evolution of displacements, velocities and stresses of dynamic ruptures, whose rupture speed range from sub-Rayleigh to supershear. The observed friction has complex evolution, featuring initial velocity strengthening followed by substantial velocity weakening. Our measurements are consistent with rate-and-state friction formulations supplemented with flash heating but not with widely used slip-weakening friction laws. This study develops a new approach for measuring local evolution of dynamic friction and has important implications for understanding earthquake hazard since laws governing frictional resistance of faults are vital ingredients in physically-based predictive models of the earthquake source

Reply to Comment on: Hawking radiation from ultrashort laser pulse filaments

A comment by R. Schutzhold et al. raises possible concerns and questions regarding recent measurements of analogue Hawking radiation. We briefly reply to the opinions expressed in the comment and sustain that the origin of the radiation may be understood in terms of Hawking emission

\u201cPort Charlotte\u201d atto secondo: la Corte corregge il Tribunale dell\u2019Unione europea sul carattere della OCM Vino, ma genera nuovi dubbi interpretativi sulla competenza degli Stati membri in materia

la nota riprende alcuni passaggi della sentenza della Corte di giustizia UE 14 settembre 2017 relativa al marchio \u201cPort Charlotte\u201d per evidenziare come nel settore vinicolo l\u2019asserito carattere esauriente della OCM Unica, ricavato dalla corte per analogia dalle osservazioni formulate nel caso BUD II sul regolamento 510/06/CE, si scontri in realt\ue0 con il persistere di numerosi elementi nella normativa vigente che concedono agli Stati membri margini di autonomia regolatoria in sovrapposizione, o, quantomeno, in parziale concorrenza con il sistema delle DOP \u2013 IGP impostato con la riforma della OCM vino del 2008. Il rischio derivante dalla posizione espressa dalla Corte in questa sentenza \ue8 che nell\u2019ambito della revisione del regolamento 607/2009/CE (di esecuzione della OCM vino) la Commissione intenda procedere ad una ulteriore semplificazione degli istituti che direttamente o indirettamente sono connessi con i meccanismi di riconoscimento e tutela dei toponimi nell\u2019Unione europea, penalizzando cos\uec ulteriormente paesi come l\u2019Italia che, a causa dell\u2019estrema variet\ue0 del proprio territorio e della stratificazione storica delle proprie tradizioni produttive, necessitano di maggiori spazi ed autonomia nella comunicazione delle caratteristiche dei propri prodotti