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(474) Production(s) de l'année 2018
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When is the Gardner transition relevant?
Auteur(s): Scalliet C.
(Séminaires)
Duke University (Durham, North Carolina, US), 2018-04-24
Résumé: The idea that glasses can become marginally stable at a Gardner transition has attracted significant interest among the glass community. Yet, the situation is confusing: even at the theoretical level, renormalization group approaches provide contradictory results on whether the transition can exist in three dimensions. The Gardner transition was searched in only two experimental studies and few specific numerical models. These works lead to different conclusions for the existence of the transition, resulting in a poor understanding of the conditions under which a marginally stable phase can be observed. The very relevance of the Gardner transition for experimental glasses is at stake.
We study analytically and numerically the Weeks-Chandler-Andersen model. By changing external parameters, we continuously explore the phase diagram and regimes relevant to granular, colloidal, and molecular glasses. We revisit previous numerical studies and confirm their conclusions. We reconcile previous results and rationalise under which conditions a Gardner phase can be observed. We find that systems in the vicinity of a jamming transition possess a Gardner phase. Our findings confirm the relevance of a Gardner transition for colloidal and granular glasses, and encourage future experimental work in this direction. For molecular glasses, we find that no Gardner phase is present, but our studies reveal instead the presence of localised excitations presumably relevant for mechanical and vibrational properties of glasses.
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A lecture on the glass transition
Auteur(s): Berthier L.
Conférence invité: Liquid Matter 2014 (Lisbonne, PT, 2018-08-21)
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Facets of glass physics
Auteur(s): Berthier L.
Conférence invité: Future of Chemical Physics (Oxford, GB, 2018-08-31)
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Transient immediate postoperative homotopic functional disconnectivity in low-grade glioma patients
Auteur(s): Coget Arthur, Deverdun J., Bonafé Alain, Dokkum Liesjet, Duffau Hugues, Molino F., Le Bars E., Menjot De Champfleur N.
(Article) Publié:
Neuroimage: Clinical, vol. 18 p.656-662 (2018)
Texte intégral en Openaccess :
Ref HAL: hal-02071081_v1
DOI: 10.1016/j.nicl.2018.02.023
WoS: 000433169000068
Exporter : BibTex | endNote
3 Citations
Résumé: Background and purposeThe aim of this longitudinal study is to evaluate large-scale perioperative resting state networks reorganization in patients with diffuse low-grade gliomas following awake surgery.Materials and methodsEighty-two patients with diffuse low-grade gliomas were prospectively enrolled and underwent awake surgical resection. Resting-state functional images were acquired at three time points: preoperative (MRI-1), immediate postoperative (MRI-2) and three months after surgery (MRI-3). We simultaneously performed perfusion-weighted imaging.
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Temperature dependence of hypersound attenuation in silica films via picosecond acoustics
Auteur(s): Foret M., Huynh A., Peronne E., Ruffle B., Perrin B., Lafosse X., Lemaitre A., Vacher R.
Conference: 16th International Conference on Phonon Scattering in Condensed Matter (Phonons 2018) (Nanjing, CN, 2018-05-30)
Ref HAL: hal-01940549_v1
Exporter : BibTex | endNote
Résumé: We reinvestigate sound dispersion and attenuation in a SiO2 layer as a function of temperature over the range 20–300 K by picosecond acoustics [1]. A pulse-echo scheme is used, where a broadband strain-pulse (centered at 120 GHz) is detected in an Al transducer after propagating back and forth through the SiO2 layer. The acoustic attenuation coefficient α within the SiO2 layer is evaluated by fitting the echoes to a mismatch model including an effective local law for the frequency dependence of attenuation over the band of the pulse. In this way, the T dependence of α in SiO2 layers could be extracted in this work for the first time. Results are found to follow rather well a model combining coupling to thermally activated relaxation mechanisms and interactions with thermal vibrations. This leads to a non-trivial variation of the attenuation coefficient with frequency and temperature. The number density of relaxing defects in the SiO2 layer is found to be slightly higher than that in bulk v-SiO2. In contrast, similar anharmonic contribution to acoustic absorption is observed in both systems. The velocity variations are also measured and are compared to the dynamical velocity changes deduced from the sound attenuation.
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Elastic and plastic transformations of vitreous silica underpressure
Auteur(s): Foret M., Ruffle B., Weigel C., Vacher R.
Conférence invité: Journées de la Matière Condensée, 2018 (Grenoble, FR, 2018-08-27)
Ref HAL: hal-01940534_v1
Exporter : BibTex | endNote
Résumé: The talk focuses on the thermodynamical properties of vitreous silica submitted to high pressures in a diamond anvil cell as obtained directly from Brillouin Light Scattering experiments or indirectly from standard relations. The analysis reveals non-negligible differences between static and dynamic compressibilities which are mostly related to the existence of thermally activated relaxational processes. Estimate of the residual densifications after complete cycles of compression/decompression is discussed.
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Laboratory of Excellence NUMEV: Digital and Hardware Solutions, Environmental and Organic Life Modeling
Auteur(s): Parmeggiani A.
Conférence invité: UC-Davis at MUSE-Unversity in Montpellier (Montpellier, FR, 2018-09-07)
Ref HAL: hal-02106125_v1
Exporter : BibTex | endNote
Résumé: NUMEV activities presentation during the visit of UC-Davis University in MUSE Montpellier
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