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See detailContribution of Spray Droplet Pinning Fragmentation to Canopy Retention
Boukhalfa, Hassina dite Hafida ULg; Massinon, Mathieu ULg; Belhamra, Mohamed et al

in Crop Protection (2014), 56

Drop behaviour during impact affects retention. The increase of adhesion is usually seen as the objective when applying crop protection products, while bouncing and shattering are seen as detrimental to ... [more ▼]

Drop behaviour during impact affects retention. The increase of adhesion is usually seen as the objective when applying crop protection products, while bouncing and shattering are seen as detrimental to spray retention. However, observation of drop impacts on barley (Hordeum vulgare L.) using high speed shadowgraphy shows that bouncing and fragmentation can occur in Cassie-Baxter as well as in Wenzel wetting regimes. In this last regime, a part of the drop may remain stuck on the surface, contributing to retention. Using simultaneous measurements of drop impacts with high speed imaging and of retention with fluorophotometry for spray mixtures on excised barley leaves using a Teejet 11003 nozzle at 0.2 MPa, it is observed that about 50% of the drops that fragmented in the Wenzel state remain on the horizontal leaf. Depending on the spray mixture, these impact outcomes accounted for 28 to 46% of retention, the higher contribution being correlated with bigger VMD (Volume Median Diameter). This contribution is not negligible and should be considered when modelling spray retention processes. [less ▲]

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See detailL’aporie de la mathématisation de la physique en contexte aristotélicien
Dubouclez, Olivier ULg

Scientific conference (2014, February)

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See detailQue peut le métalangage ? What can metalanguage do ?
Dondero, Maria Giulia ULg; Provenzano, François ULg; Klinkenberg, Jean-Marie ULg et al

Book published by Presses Universitaires de Liège (2014)

In the social sciences, research that is conveyed in a display of technical language is not always seen in a good light. This is a trend particularly in semiotics. As a field of study, it has a reputation ... [more ▼]

In the social sciences, research that is conveyed in a display of technical language is not always seen in a good light. This is a trend particularly in semiotics. As a field of study, it has a reputation for eagerness to use semio-jargon at the worst, or at best, a reputation for walling itself off in a self-reflective meta-language. It is true that the best known and most cited treatise on structural semiotics, by Greimas and Courtés, was published as an Analytical Dictionary. And it is also true that Peirce's work is prodigiously crammed with terminological inventions and speculations. It would seem that in both cases, the quest for scientific rigor took precedence over elegance of expression and of so-called natural discourse. Nothing new under the sun, n'est-ce pas? They say that a courtesan under Louis XIV scandalized the Sun King's court by uttering a technical term in the king's bedchamber, which illustrates how far back the issue goes; it certainly didn't begin with the development of the academic study of signs. In issue 4 of Signata we would like to examine the various aspects of building the meta-language of semiotics. The intention is not to adopt a philological perspective, but to look at the issue of terminologies in current scientific epistemology. We will examine the diversity of the possible meta-languages (natural language versus technical language?), the influence of related disciplines (what implications do the borrowed terms from grammar, logic, mathematics, and so on have for semiotics?), the reasons — explicit or not — for the choices made, and the stylistic impacts of those choices. An inquiry of this sort could go in many directions. What follows is an open-ended, non-exhaustive enumeration: Semiotics: A special case? Is it actually true that the semiotic approach generates a more prolific meta-linguistic output than other disciplines? How and why? It would be interesting, for example, to do comparisons with these more or less related disciplines (linguistics, sociology, psychology, etc.), to assess whether their rapport with the meta-language might possibly be different, and the reasons for and effects of those differences. In these assessments, of course, there arises the issue of "natural language", which is so readily its own meta-language: Are there disciplines that reconcile themselves with this supposed naturalness without any detriment? An updated meta-language may be deemed as unavoidable for a discipline whose vocation is to generalize, which implies substantial modeling power. But what do we find in philosophy, which can be expressed without abandoning natural language, and which seems to incur less reproach for its jargon than semiotics? The archaeology of meta-languages Another line of inquiry would be of a genealogical nature: This would involve examining the theoretical justifications that underpin meta-language borrowings from this or that other discipline, at this or that other time in its history, and the repercussions, both stylistic and epistemological, of the trade in terminology. On this score, we note that classical structuralism has expressed itself to a great extent in a grammatical and more broadly linguistic language (actants, modalities, deixis, articulation, semes, etc.). But it is common knowledge that other approaches to semantic facts have favored the language of logic. And yet others have shown that it is both possible and effective to use language taken from geometry or optics. In addition to these, from the perspective of the primacy of perception, the language of the natural sciences must be included — particularly that of the neurosciences —, and the language of sensory forms from phenomenology. Whether one is helping oneself to terms like "isotopy" and "valence" from physics and chemistry or "topology" from mathematics, these are not innocent choices in a discipline that has blazed its trail through the social sciences. The epistemological influence of the meta-language. Without any doubt, herein lies the most complex, ambivalent issue. Firstly, when one adopts a meta-language, by definition one views the object of study as a language (whether it is the natural language or the language of images, or the language of social practices). Yet this operation is so laden with consequences that to enumerate them would be an impossible task. We will merely note that many theoretical categories and analytical tools seem to emerge directly from the choice of a particular meta-language and the distance dictated by it. Secondly, opting for one meta-language over another is ipso facto a choice of which explanatory form the analysis will use. It follows that working on the meta-language, far from being a deathly sterile activity, is a practice intended to generate the form the explanation will take (which is without any doubt a major issue in scientific discussion). But these two epistemological impacts of meta-language generation can trigger a great deal of discussion on what we might call "the adverse effects" of the chosen options. For example, if there is a consensus within a group on a particular meta-language (such as in Greimassian semiotics), it may become just a template to apply, simply a schema to project onto objects; but if it is an object of inquiry (such as in Peirce's work), it may yield an approach that is more theoretical than practical. Hence the question: Hasn't semiotics in fact been above all a field with a mix of applied and self-reflective approaches? And in any case, does it truly explain things when one supports a meta-language and seeks to apply it and think within its terms? For example, we might question whether the meta-linguistic power of semiotics hasn't made it a discipline that is quick to generalize, and kept it from focusing on the singularity of its objects. We might also question whether semiotic research isn't all too often more formal than substantial, both in the Hjelmselvian sense and the usual sense. Ultimately, even further up the line, one could debate the epistemological possibility of the meta-language itself — as the poststructuralist philosophies have done. Isn't the distinction between object language and meta-language actually a bit utopian in the natural languages, since it assumes that the terms completely lose their reflexivity? Lastly, we might question whether the meta-language as a theoretical tool doesn't entail more than just artless transparency, but also an effort to define the theory within a restrictive set of evidence. For example, to bring up the "semiotic square" presupposes that there is always a semiotic square that explains the basis of the discourse (in such a way that what was a working hypothesis could become a non-falsifiable theory). The socio-rhetorical effects of the meta-language Aside from the epistemological requirements, when technical terminology is reworked, this has impacts on the circulation of concepts and their appropriation by different groups, which then affects group members' recognition of one another and how they differentiate one group from another. The boundary drawn on a conceptual system by a terminological apparatus thus gives rise to corollary inclusion-exclusion repercussions that are not unimportant. There are fights over terminological legitimacy, whose foremost characteristic is actually that they are not formulated as such. Any meta-language also has impacts on the social aspects of thinking. This is especially true of the meta-language of semiotics, because, due to its dedication to generality and transposability, it must fully support deconstruction. On the other side of the coin, one can maintain that meta-language is to objects what bureaucracy is to communities: It is helpful in creating order and making distinctions, in establishing levels and empty slots, but the risk, then, is that it may become an end in itself that must be maintained and tended, and that it ultimately disallows acting and thinking in other ways. In the light of this rhetorical approach, finally, we will set down some things to consider on the manner in which semiotics talks to itself: Are "techno-speak" and "jargon" inevitable? Are "elegance" and "practicality" valid criteria for a meta-language? What impacts on the meta-language are due to the obligation we often have in semiotics to dialogue with those outside our field: Can/ should this influence the way semiotics is communicated? And what is the cost of this influence? [less ▲]

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See detailSubspace and nonlinear-normal-modes-based identification of a beam with softening-hardening behaviour
Grappasonni, Chiara ULg; Noël, Jean-Philippe ULg; Kerschen, Gaëtan ULg

in Proceedings of the International Modal Analysis Conference (IMAC) XXXII (2014, February)

The capability to reproduce and predict with high accuracy the behaviour of a real system is a fundamental task of numerical models. In nonlinear structural dynamics, additional parameters compared to ... [more ▼]

The capability to reproduce and predict with high accuracy the behaviour of a real system is a fundamental task of numerical models. In nonlinear structural dynamics, additional parameters compared to classical linear modelling, which include the nonlinear coefficient and the mathematical form of the nonlinearity, need to be identified to bring the numerical predictions in good agreement with the experimental observations. In this context, the present paper presents a method for the identification of an experimental cantilever beam with a geometrically nonlinear thin beam clamped with a prestress, hence giving rise to a softening-hardening nonlinearity. A novel nonlinear subspace identification method formulated in the frequency domain is first exploited to estimate the nonlinear parameters of the real structure together with the underlying linear system directly from the experimental tests. Then a finite element model, built from the estimated parameters, is used to compute the backbone of the first nonlinear normal mode motion. These numerical evaluations are compared to a nonlinear normal modes-based identification of the structure using system responses to stepped sine excitation at different forcing levels. [less ▲]

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See detailArts et sciences. Approches sémiotiques et philosophiques des images
Dondero, Maria Giulia ULg; Beyaert-Geslin, Anne

Book published by Presses universitaires de Liège (2014)

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See detailLes grands principes de l'aménagement du territoire
Habran, Maxime ULg

Learning material (2014)

Il s'agit d'une introduction aux principes en matière d'aménagement du territoire. Cette leçon a pour but d'expliquer les principales démarches à effectuer dans le cadre d'une demande d'urbanisme.

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See detailQuasicontinuum study of the shear behavior of defective tilt grain boundaries in Cu
Péron-Lührs, Vincent ULg; Sansoz, Frédéric; Noels, Ludovic ULg

in Acta Materialia (2014), 64

Atomistic simulations using the quasicontinuum method are used to study the role of vacancy defects and angström-scale voids on the mechanical behavior of five tilt bicrystals containing grain boundaries ... [more ▼]

Atomistic simulations using the quasicontinuum method are used to study the role of vacancy defects and angström-scale voids on the mechanical behavior of five tilt bicrystals containing grain boundaries (GBs) that have been predicted to exhibit characteristic deformation processes of nanocrystalline and nanotwinned metals: GB-mediated dislocation emission, interface sliding, and shear-coupled GB migration. We demonstrate that such nanoscale defects have a profound impact on interfacial shear strength and underlying deformation mechanisms in copper GBs due to void-induced local stresses. In asymmetric high and low angle GBs, we find that voids become preferential sites for dislocation nucleation when the void size exceeds 4 Å. In symmetric 9(221) GBs prone to sliding, voids are shown to shield the local shear stress, which considerably reduces the extent of atom shuffling at the interface. In symmetric Sigma5(210) and Sigma27(115) GBs, we find that the effect of voids on shear-coupled GB migration depends on the GB tilt direction considered, as well as on the size and number of voids. Remarkably, large voids can completely abate the GB migration process in Sigma 27(115) GBs. For all GB types, the interfacial shear strength is shown to decrease linearly as the volume fraction of voids at the interface increases; however, this study also suggests that this decrease is much more pronounced in GBs deforming by sliding than by dislocation nucleation or migration, owing to larger void-induced stresses. [less ▲]

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See detailMicrofluidic on optical fibers: Towards a new kind of fluorescent biosensor
Lismont, Marjorie ULg; Vandewalle, Nicolas ULg; Weyer, Floriane ULg et al

Poster (2014, February)

In recent works, the behavior of droplets moving along vertical treads due to gravity was studied. It appeared that the droplet can be stopped by encountering a horizontal fiber depending on droplet ... [more ▼]

In recent works, the behavior of droplets moving along vertical treads due to gravity was studied. It appeared that the droplet can be stopped by encountering a horizontal fiber depending on droplet volumes and fiber characteristics. On the basis of this behavior and by replacing treads by two crossed optical fibers, it is possible to combine fluidics and optics to develop a new kind of fluorescent sensor. In our work, the intersection between two crossed optical fibers is used as the basic unit of an original optofluidic biosensor. These two optical fibers are used as droplets carriers: one for probe molecules and the other one for target species. The fiber's junction catches the droplets and act as a reaction center. The main advantage of using optical fibers resides in their ability to propagate and collect light to and from the droplet localized at the fiber's crossing. This optical fiber configuration can therefore allow the study of biological interactions using fluorescent labels. This new and versatile detection scheme was validated on a calcium indicator where ions detection is accomplished by using a dye, Oregon green Bapta-2, that has a Ca 2+ recognition group as well as an entity exhibiting fluorescence. A FRET recognition event, between Rh-Con A and FITC-Dextran, was also investigated to detect glucose. Finally, a prototype of a multiplexing device, composed of several juxtaposed fibers' junctions, was developed. [less ▲]

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See detailMetal Enhanced Fluorescence: effect of surface coating
Lismont, Marjorie ULg; François, Alexandre; Dreesen, Laurent ULg et al

in SPIE proceeding (2014, February)

Among the emerging treatments for cancer, Photodynamic Therapy (PDT) is thought to be one of the most promising. PDT uses light sensitive molecules, or photosensitizer, to produce, under specific ... [more ▼]

Among the emerging treatments for cancer, Photodynamic Therapy (PDT) is thought to be one of the most promising. PDT uses light sensitive molecules, or photosensitizer, to produce, under specific irradiation, toxic reactive oxygen species (ROS) to kill cancer cells. However, the amount of ROS generated is limited by both the fluorescence lifetime of the photosensitizer and its concentration around the cancer cells. Metal Enhanced Fluorescence (MEF), a phenomenon arising when a fluorophore is in closed proximity to a metallic structure such as metallic films or nanostructures, is seen as a way to solve these problems by reducing the fluorescence lifetime and increasing the fluorescence emission of the fluorophore. Protoporphyrin IX (PpIX) is a commonly used photosensitizer to treat skin cancers, which presents an intense absorption band around 400 nm while emitting around 630 nm. Because silver nanoparticles (Ag NPs) exhibit a strong Localized Surface Plasmon Resonance (LSPR) around 400 nm, MEF of the PpIX is expected when immobilized onto Ag NPs. Here, we investigate the relevant parameters influencing the coupling effects between the LSPR in Ag NPs and PpIX attached onto the Ag NPs surface when the Ag NPs are dispersed in solution or electrostatically bound to a glass slide. In particular, we study the distance-dependent of MEF by applying multiple layers of polyelectrolyte to progressively increase the distance between Ag NPs and PpIX, covalently bond to the last polyelectrolyte layer as well as exploring the use of Ag NPs of different sizes ranging from 40 to 100 nm. [less ▲]

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See detailImplementation of the ALERT algorithm, a new dispatcher-assisted telephone cardiopulmonary resuscitation protocol, in non-Advanced Medical Priority Dispatch System (AMPDS) Emergency Medical Services centres.
STIPULANTE, Samuel ULg; Tubes, Rebecca; Fassi, Mehdi El et al

in Resuscitation (2014), 85(2), 177-181

Objectives: Early bystander cardiopulmonary resuscitation (CPR) is a key factor in improving survival from out-of-hospital cardiac arrest (OHCA). The ALERT (Algorithme Liegeois d'Encadrement a la ... [more ▼]

Objectives: Early bystander cardiopulmonary resuscitation (CPR) is a key factor in improving survival from out-of-hospital cardiac arrest (OHCA). The ALERT (Algorithme Liegeois d'Encadrement a la Reanimation par Telephone) algorithm has the potential to help bystanders initiate CPR. This study evaluates the effectiveness of the implementation of this protocol in a non-Advanced Medical Priority Dispatch System area. Methods: We designed a before and after study based on a 3-month retrospective assessment of victims of OHCA in 2009, before the implementation of the ALERT protocol in Liege emergency medical communication centre (EMCC), and the prospective evaluation of the same 3 months in 2011, immediately after the implementation. Results: At the moment of the call, dispatchers were able to identify 233 OHCA in the first period and 235 in the second. Victims were predominantly male (59%, both periods), with mean ages of 64.1 and 63.9 years, respectively. In 2009, only 9.9% victims benefited from bystander CPR, this increased to 22.5% in 2011 (p<0.0002). The main reasons for protocol under-utilisation were: assistance not offered by the dispatcher (42,3%), caller physically remote from the victim (20.6%). Median time from call to first compression, defined here as no flow time, was 253sec in 2009 and 168sec in 2011 (NS). Ten victims were admitted to hospital after ROSC in 2009 and 13 in 2011 (p=0.09). Conclusion: From the beginning and despite its under-utilisation, the ALERT protocol significantly improved the number of patients in whom bystander CPR was attempted. [less ▲]

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See detailLa paradoja de la literatura de la migración latinoamericana contemporánea: algunas reflexiones a partir de la obra de Juan Carlos Méndez Guédez
Berlage, Pauline ULg

in Giuliani, L; Trapassi, L.; Martos, J. (Eds.) Lejos es aquí. Far Away is Here (2014)

¿cómo definir el campo de estudio de la literatura de la migración hispanoamericana? ¿Cuál sería la validez de tal “corriente”? ¿Acaso no se podrían definir todas las producciones literarias ... [more ▼]

¿cómo definir el campo de estudio de la literatura de la migración hispanoamericana? ¿Cuál sería la validez de tal “corriente”? ¿Acaso no se podrían definir todas las producciones literarias contemporáneas como una literatura transnacional?Basándome en la obra del escritor venezolano español Juan Carlos Méndez Guédez, éstas son las preguntas y reflexiones que me he planteado en cuanto a la validez y al abanico de posibilidades que abre el concepto de literatura de la migración latinoamericana. Mi objetivo aquí es ir más allá del debate terminológico que discute la etiqueta correcta para caracterizar esta literatura y destacar algunas de las numerosas cuestiones que suscita. [less ▲]

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See detailL'invité - Damien Ernst - "Nous allons vers une globalisation du marché de l'électricité"
Ernst, Damien ULg

Article for general public (2014)

En décembre 2013, Damien Ernst, Professeur à l’ULG, a donné une conférence au CESW intitulée : «Vers une globalisation du marché de l’électricité. Quel rôle pour les acteurs du secteur belge de ... [more ▼]

En décembre 2013, Damien Ernst, Professeur à l’ULG, a donné une conférence au CESW intitulée : «Vers une globalisation du marché de l’électricité. Quel rôle pour les acteurs du secteur belge de l’électricité?». Damien Ernst est un observateur privilégié du secteur énergétique belge, et plus particulièrement de tout ce qui concerne le secteur de l’électricité. Auteur de nombreuses publications et études, Damien Ernst s’est notamment interrogé sur les perspectives des énergies renouvelables en Belgique. Damien Ernst est l’invité de ce numéro 120 de la revue Wallonie. Dans son interview, il nous explique pourquoi la globalisation du marché de l’électricité est inéluctable et quelles en seront les conséquences, pour les entreprises du secteur et pour la Wallonie. [less ▲]

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See detailWhite Matter Changes in Comatose Survivors of Anoxic Ischemic Encephalopathy and Traumatic Brain Injury: Comparative Diffusion-Tensor Imaging Study
Van Der Eerden, Anke; Khalilzadeh, Omid; Perlbarg, Vincent et al

in Radiology (2014), 270

Purpose:To analyze white matter pathologic abnormalities by using diffusion-tensor (DT) imaging in a multicenter prospective cohort of comatose patients following cardiac arrest or traumatic brain injury ... [more ▼]

Purpose:To analyze white matter pathologic abnormalities by using diffusion-tensor (DT) imaging in a multicenter prospective cohort of comatose patients following cardiac arrest or traumatic brain injury (TBI). Materials and Methods: Institutional review board approval and informed consent from proxies and control subjects were obtained. DT imaging was performed 5–57 days after insult in 49 cardiac arrest and 40 TBI patients. To control for DT imaging–processing variability, patients’ values were normalized to those of 111 control subjects. Automated segmentation software calculated normalized axial diffusivity (λ1) and radial diffusivity (λ) in 19 predefined white matter regions of interest (ROIs). DT imaging variables were compared by using general linear modeling, and side-to-side Pearson correlation coefficients were calculated. P values were corrected for multiple testing (Bonferroni). Results:In central white matter, λ1 differed from that in control subjects in six of seven TBI ROIs and five of seven cardiac arrest ROIs (all P < .01). The λ differed from that in control subjects in all ROIs in both patient groups (P < .01). In hemispheres, λ1 was decreased compared with that in control subjects in three of 12 TBI ROIs (P < .05) and nine of 12 cardiac arrest ROIs (P < .01). The λ was increased in all TBI ROIs (P < .01) and in seven of 12 cardiac arrest ROIs (P < .05). Cerebral hemisphere λ1 was lower in cardiac arrest than in TBI in six of 12 ROIs (P < .01), while λ was higher in TBI than in cardiac arrest in eight of 12 ROIs (P < .01). Diffusivity values were symmetrically distributed in cardiac arrest (P < .001 for side-to-side correlation) but not in TBI patients. Conclusion:DT imaging findings are consistent with the known predominance of cerebral hemisphere axonal injury in cardiac arrest and chiefly central myelin injury in TBI. This consistency supports the validity of DT imaging for differentiating axon and myelin damage in vivo in humans. [less ▲]

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See detailReliability and validity of a new French-language triage algorithm : the ELISA scale
JOBE, Jérôme ULg; Ghuysen, Alexandre ULg; GERARD, P et al

in Emergency Medicine Journal (2014), 31(2), 115-20

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See detailInfiniment petits en économie
Bair, Jacques ULg; Henry, Valérie ULg

in Tangente, l'aventure mathématique (2014), 156

Depuis la création de l'analyse mathématique, principalement par Newton et Leibniz, les économistes ont découvert qu'ils pouvaient exploiter avec succès le concept mathématique d'infiniment petit dans ... [more ▼]

Depuis la création de l'analyse mathématique, principalement par Newton et Leibniz, les économistes ont découvert qu'ils pouvaient exploiter avec succès le concept mathématique d'infiniment petit dans leurs raisonnements. Dans cet article est donné un aperçu des premières apparitions de l'analyse infinitésimale en économie. [less ▲]

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See detailEffective stress method to be used in beam finite elements to take local instabilities into account
Franssen, Jean-Marc ULg; Cowez, Baptiste; Gernay, Thomas ULg

in Proceedings of the 11th IAFSS Symposium (2014, February)

In the fire situation, Bernoulli beam finite elements are the workhorse used in numerical calculation model for simulating the behaviour of the structure. Such finite elements treat all sections as class ... [more ▼]

In the fire situation, Bernoulli beam finite elements are the workhorse used in numerical calculation model for simulating the behaviour of the structure. Such finite elements treat all sections as class 1 (stocky) sections whatever the slenderness of the plates that make the section, allowing the development of a full plastic stress distribution in the section which leads to complete plastic redistribution along the members in the structure. This type of element is thus not adapted for modeling structures that contain slender sections of class 2, 3 or 4. This document presents a new approach to take into account local instabilities in slender sections using beam finite elements. The new approach is based on an effective constitutive law of steel. The effective law is not symmetrical with respect to tension and compression because, in tension, the stress-strain relationship is not modified whereas, in compression, the stress-strain relationship is modified. [less ▲]

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