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npj Computational Materials 2022年第1期8卷 197-205页

作者： Paolo Pegolo Stefano Baroni Federico Grasselli sissa—Scuola Internazionale Superiore di Studi Avanzati 34136TriesteItaly CNR-Istituto Officina dei Materiali SISSA34136TriesteItaly COSMO—Laboratory of Computational Science and Modelling IMXÉcole Polytechnique Fédérale de Lausanne1015LausanneSwitzerland

Despite governing heat management in any realistic device,the microscopic mechanisms of heat transport in all-solid-state electrolytes are poorly known:existing calculations,all based on simplistic semi-empirical models,are unreliable for superionic conductors and largely overestimate their thermal conductivity.In this work,we deploy a combination of state-of-the-art methods to calculate the thermal conductivity of a prototypical Li-ion conductor,the Li_(3)ClO antiperovskite.By leveraging ab initio,machine learning,and force-field descriptions of interatomic forces,we are able to reveal the massive role of anharmonic interactions and diffusive defects on the thermal conductivity and its temperature dependence,and to eventually embed their effects into a simple rationale which is likely applicable to a wide class of ionic conductors.

关键词： transport conductivity eventually

Hydrodynamic finite-size scaling of the thermal conductivity in glasses

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npj Computational Materials 2023年第1期9卷 696-706页

作者： Alfredo Fiorentino Paolo Pegolo Stefano Baroni sissa—Scuola Internazionale Superiore di Studi Avanzati 34136 TriesteItaly CNR-IOM—Istituto Officina Materiali SISSA Unit34136 TriesteItaly

In the past few years,the theory of thermal transport in amorphous solids has been substantially extended beyond the Allen-Feldman model.The resulting formulation,based on the Green-Kubo linear response or the Wigner-transport equation,bridges this model for glasses with the traditional Boltzmann kinetic approach for crystals.The computational effort required by these methods usually scales as the cube of the number of atoms,thus severely limiting the size range of computationally affordable glass models.Leveraging hydrodynamic arguments,we show how this issue can be overcome through a simple formula to extrapolate a reliable estimate of the bulk thermal conductivity of glasses from finite models of moderate size.We showcase our findings for realistic models of paradigmatic glassy materials.

关键词： glasses conductivity thermal

Approximation of the Spectral Fractional Powers of the Laplace-Beltrami Operator

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Numerical Mathematics(Theory,Methods and Applications) 2022年第4期15卷 1193-1218页

作者： Andrea Bonito Wenyu Lei Department of Mathematics Texas A&M UniversityCollege StationTX 77843USA sissa-International School for Advanced Studies Via Bonomea 26534136 TriesteItaly

We consider numerical approximation of spectral fractional Laplace-Beltrami problems on closed surfaces.The proposed numerical algorithms rely on their Balakrishnan integral representation and consists a sinc quadrature coupled with standard finite element methods for parametric surfaces.Possibly up to a log term,optimal rate of convergence are observed and derived analytically when the discrepancies between the exact solution and its numerical approximations are measured in L^(2)and H^(1).The performances of the algorithms are illustrated on different settings including the approximation of Gaussian fields on surfaces.

关键词： Fractional diffusion Laplace-Beltrami FEM parametric methods on surfaces Gaussian fields

SBV REGULARITY OF GENUINELY NONLINEAR HYPERBOLIC SYSTEMS OF CONSERVATION LAWS IN ONE SPACE DIMENSION

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Acta Mathematica Scientia 2012年第1期32卷 380-388页

作者： Stefano Bianchini sissa via Bonomea 265IT-34136 Trieste

The problem of the presence of Cantor part in the derivative of a solution to a hyperbolic system of conservation laws is considered. An overview of the techniques involved in the proof is given, and a collection of r... 详细信息

关键词： hyperbolic systems conservation laws SBV regularity

Rational solutions of Painlevé-Ⅱequation as Gram determinant

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Chinese Physics B 2023年第12期32卷 200-211页

作者：张晓恩陆冰滢 College of Mathematics and Systems Science Shandong University of Science and TechnologyQingdao 266590China sissa Via Bonomea 265TriesteItaly

Under the Flaschka-Newell Lax pair,the Darboux transformation for the Painlevé-Ⅱequation is constructed by the limiting technique.With the aid of the Darboux transformation,the rational solutions are represented by the Gram determinant,and then we give the large y asymptotics of the determinant and the rational solutions.Finally,the solution of the corresponding Riemann-Hilbert problem is obtained from the Darboux matrices.

关键词： Painlevé-Ⅱequation Darboux transformation rational solutions

Tuning of neocortical astrogenesis rates by Emx2 in neural stem cells

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Neural Regeneration Research 2015年第4期10卷 550-551页

作者： Carmen Falcone Antonello Mallamaci Laboratory of Cerebral Cortex Development SISSATriest I-36134Italy

Generation of astrocytes within the murine developing cerebral cortex mainly takes place during the first postnatal week, after neuronogenesis and prior to the bulk of oligogenesis. This process involves a great variety of highly complex regulatory mechanisms. Astrocytic outputs depend on two primary factors： progressive commitment of multipotent precursors to astroglial fates and proper tuning of proliferation of astrocyte-committed progenitors. To date, several regulatory mechanisms have been identified for the former process, while very little is known about modulation of astroblast proliferation （reviewed in Mallamaci,

关键词： Tuning of neocortical astrogenesis rates by Emx2 in neural stem cells NSCs Figure GOF stem

KAM Theory for Partial Differential Equations

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Analysis in Theory and Applications 2019年第3期35卷 235-267页

作者： Massimiliano Berti Massimiliano Berti SISSA

In the last years much progress has been achieved in KAM theory concerning bifurcation of quasi-periodic solutions of Hamiltonian or reversible partial differential equations.We provide an overview of the state of the... 详细信息

关键词： KAM for PDEs quasi-periodic solutions small divisors infinite dimensional Hamiltonian and reversible systems water waves nonlinear wave and Schr?dinger equations KdV

The density profiles of dark matter halos in spiral galaxies

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Natural Science 2012年第5期4卷 265-270页

作者： Gianluca Castignani Noemi Frusciante Daniele Vernieri Paolo Salucci INFN Istituto Nazionale di Fisica Nucleare Sezione di Trieste Trieste Italy NFN Istituto Nazionale di Fisica Nucleare Sezione di Trieste Trieste Italy sissa-isas International School for Advanced Studies sissa-isas International School for Advanced Studies Trieste Italy

In spiral galaxies, we explain their non-Keplerian rotation curves (RCs) by means of a non-luminous component embedding their stellar-gaseous disks. Understanding the detailed properties of this component (labelled Dark Matter, DM) is one of the most pressing issues of Cosmology. We investigate the recent relationship (claimed by Walker et al. 2010, hereafter W + 10) between r, the galaxy radial coordinate, and Vh(r), the dark halo contribution to the circular velocity at r, 1) in the framework of the Universal Rotation Curve (URC) paradigm and directly 2) by means of the kinematics of a large sample of DM dominated spirals. We find a general agreement between the W + 10 claim, the distribution of DM emerging from the URC and that inferred in the (low luminosity) objects of our sample. We show that such a phenomenology, linking the spiral’s luminosity, radii and circular velocities, implies an evident inconsistency with (naive) predictions in the Λ Cold Dark Matter (ΛCDM) scenario.

关键词： Galaxies Spiral Kinematics and Dynamics Dark Matter

Machine learning of superconducting critical temperature from Eliashberg theory

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npj Computational Materials 2022年第1期8卷 113-120页

作者： S.R.Xie Y.Quan A.C.Hire B.Deng J.M.DeStefano I.Salinas U.S.Shah L.Fanfarillo J.Lim J.Kim G.R.Stewart J.J.Hamlin P.J.Hirschfeld R.G.Hennig Department of Materials Science and Engineering University of FloridaGainesvilleFL32611USA Quantum Theory Project University of FloridaGainesvilleFL32611USA Department of Physics University of FloridaGainesvilleFL32611USA Scuola Internazionale Superiore di Studi Avanzati(sissa) Via Bonomea 26534136TriesteItaly

The Eliashberg theory of superconductivity accounts for the fundamental physics of conventional superconductors,including the retardation of the interaction and the Coulomb pseudopotential,to predict the critical temperature T_(c).McMillan,Allen,and Dynes derived approximate closed-form expressions for the critical temperature within this theory,which depends on the electron–phonon spectral functionα^(2)F(ω).Here we show that modern machine-learning techniques can substantially improve these formulae,accounting for more general shapes of theα^(2)F function.Using symbolic regression and the SISSO framework,together with a database of artificially generatedα^(2)F functions and numerical solutions of the Eliashberg equations,we derive a formula for T_(c)that performs as well as Allen–Dynes for low-T_(c)superconductors and substantially better for higher-T_(c)ones.This corrects the systematic underestimation of Tc while reproducing the physical constraints originally outlined by Allen and Dynes.This equation should replace the Allen–Dynes formula for the prediction of higher-temperature superconductors.

关键词： function. critical theory

Dynamic expression of ATF3 as a novel tool to study activation and migration of endogenous spinal stem cells and their role in neural repair

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Neural Regeneration Research 2015年第5期10卷 713-714页

作者： Miranda Mladinic Andrea Nistri Department of Biotechnology University of Rijeka Neuroscience Department International School for Advanced Studies (SISSA)34136 TriesteItaly (Nistri 1)

One of the major problems of modern neurobiology is how to replace dead or damaged neurons in the human brain or spinal cord after injury or as a consequence of neurodegenerative dis- eases. In fact, because adult mammalian neurons are post-mi- totic cells that cannot divide to replace dead cells, loss due to lesion or disease is permanent. Furthermore, surviving neurons have modest capacity to regenerate their damaged axons and re-establish functional connections. Thus, a gradual neurode- generative scenario with certain similarities in stroke, brain or spinal cord injuries and neurological diseases like Alzheimer＇s disease is produced. These conditions represent the major disease burden of the modern world in terms of mortality, dis- ability, productivity loss and health-care costs （World Health Organization, 2008）. While much effort has been directed to understand the molecular and cellular mechanisms involved in the pathology of these diseases to set new effective treatments, many neuroprotective and regenerative approaches, although showing positive results in preclinical studies, have so far failed to provide strong benefit to patients.

关键词： stem cell ATF