Derivative Expansion Research Articles

Characterization and Therapeutic Application of Mesenchymal Stem Cells with Neuromesodermal Origin from Human Pluripotent Stem Cells.

Rationale: Mesenchymal stem cells (MSC) hold great promise in the treatment of various diseases including autoimmune diseases, inflammatory diseases, etc., due to their pleiotropic properties. However, largely incongruent data were obtained from different MSC-based clinical trials, which may be partially due to functional heterogeneity among MSC. Here, we attempt to derive homogeneous mesenchymal stem cells with neuromesodermal origin from human pluripotent stem cells (hPSC) and evaluate their functional properties.Methods: Growth factors and/or small molecules were used for the differentiation of human pluripotent stem cells (hPSC) into neuromesodermal progenitors (NMP), which were then cultured in animal component-free and serum-free induction medium for the derivation and long-term expansion of MSC. The resulted NMP-MSC were detailed characterized by analyzing their surface marker expression, proliferation, migration, multipotency, immunomodulatory activity and global gene expression profile. Moreover, the in vivo therapeutic potential of NMP-MSC was detected in a mouse model of contact hypersensitivity (CHS).Results: We demonstrate that NMP-MSC express posterior HOX genes and exhibit characteristics similar to those of bone marrow MSC (BMSC), and NMP-MSC derived from different hPSC lines show high level of similarity in global gene expression profiles. More importantly, NMP-MSC display much stronger immunomodulatory activity than BMSC in vitro and in vivo, as revealed by decreased inflammatory cell infiltration and diminished production of pro-inflammatory cytokines in inflamed tissue of CHS models.Conclusion: Our results identify NMP as a new source of MSC and suggest that functional and homogeneous NMP-MSC could serve as a candidate for MSC-based therapies.

Holographic turbulence in Einstein-Gauss-Bonnet gravity at large D

We study the holographic hydrodynamics in the Einstein-Gauss-Bonnet (EGB) gravity in the framework of the large D expansion. We find that the large D EGB equations can be interpreted as the hydrodynamic equations describing the conformal fluid. These fluid equations are truncated at the second order of the derivative expansion, similar to the Einstein gravity at large D. From the analysis of the fluid flows, we find that the fluid equations can be taken as a variant of the compressible version of the non-relativistic Navier-Stokes equations. Particularly, in the limit of small Mach number, these equations could be cast into the form of the incompressible Navier-Stokes equations with redefined Reynolds number and Mach number. By using numerical simulation, we find that the EGB holographic turbulence shares similar qualitative feature as the turbulence from the Einstein gravity, despite the presence of two extra terms in the equations of motion. We analyze the effect of the GB term on the holographic turbulence in detail.

Undressing confining flux tubes with TT¯

Lattice QCD simulations provide crucial information about the worldsheet dynamics of confining strings (flux tubes). An accurate extraction of the worldsheet $S$-matrix from lattice spectra requires accounting for polarization effects. Approximate integrability of the low energy worldsheet theory makes it possible to apply the Thermodynamic Bethe Ansatz to incorporate polarization effects at all orders in the number of windings and at the leading order in the derivative expansion. However, a systematic application of this technique in the presence of non-integrable effects and for multiparticle states becomes increasingly challenging. We point out that a recently understood equivalence between gravitational dressing and $T\bar{T}$ deformation provides a fully systematic and straightforward recipe to incorporate the leading polarization effects in the presence of an arbitrary inelasticity and for any number of particles. We illustrate this technique with several examples.

Investor behavior, information disclosure strategy and counterparty credit risk contagion

Counterparty credit risk caused by the excessive expansion of credit derivatives is becoming more and more prominent. The study of evolution mechanism of its contagion will help the financial regulators set up a scientific and accessible prevention and control strategy. From the cross perspective of behavioral finance and information economics, this study analyzes the mechanism of counterparty credit risk contagion. Based on the epidemic model, a network model of it is built with the consideration of investor behavior and information disclosure strategy. The network topology characteristics of it are analyzed in theory. Meanwhile, this study analyzes the evolution characteristics of it in numerical simulation. The main conclusions are as follows: First, investor behavior or information disclosure strategy only affects counterparty credit risk contagion in local credit asset network, while it is gradually disappearing in global credit asset network. Second, noise can enhance the impact intensity of investor behavior or information disclosure strategy on counterparty credit risk contagion, and lead to the spread of counterparty credit risk synchronously in local and global credit asset networks. Third, information transmission rate has “local strengthening effect” on investor behavior. The timing of information release and the tendency of information disclosure exert a “global suppression effect” on the influence of investors, and the ability of investor information decision-making has a “local suppression effect” on the timing of information release and the tendency of information disclosure. Through the comprehensive adjustment of investor behavior and information disclosure strategy, the goal of preventing and controlling counterparty credit risk contagion can be realized in local and global credit asset networks.

Derivatives clearing infrastructure renewal in Japan: The impending post-trade market revolution

This is the second in a series of reports on the securities settlement revolution in Japan. It is based on a Celent survey conducted in 2017 about technology use in post-trade operations. It offers a comprehensive overview of the current state of market participants and the challenges they face in the ongoing market transformation, while offering proposals related to the potential of emerging technologies, innovation, legacy issues and ecosystem migration. Japan’s derivative market has grown in leaps and bounds in tandem with the expansion of market derivatives and securities over-the-counter (OTC) derivatives. Work on an initiative to renew the clearing infrastructure has followed in the wake of market integration already completed on the execution system side by virtue of the new Japan Global Access Trading Engine (J-GATE; futures, options) that began operating in July 2016. The Japan Securities Clearing Corporation (JSCC) new clearing system will mandate action on the part of market participants in areas including the revision of clearing services, risk management and clearing systems. While many of the major participants in the clearing market appear to have already completed preparation for the transition to the new system, there remain stragglers that are in the process of responding — and even some who have yet to take action. At the same time, the actions being taken by these entities to respond to the coming changes are also thrusting challenges related to the overall posttrade market into the limelight.

Effective action for relativistic hydrodynamics: fluctuations, dissipation, and entropy inflow

We present a detailed and self-contained analysis of the universal SchwingerKeldysh effective field theory which describes macroscopic thermal fluctuations of a relativistic field theory, elaborating on our earlier construction [1]. We write an effective action for appropriate hydrodynamic Goldstone modes and fluctuation fields, and discuss the symmetries to be imposed. The constraints imposed by fluctuation-dissipation theorem are manifest in our formalism. Consequently, the action reproduces hydrodynamic constitutive relations consistent with the local second law at all orders in the derivative expansion, and captures the essential elements of the eightfold classification of hydrodynamic transport of [2]. We demonstrate how to recover the hydrodynamic entropy and give predictions for the non-Gaussian hydrodynamic fluctuations.The basic ingredients of our construction involve (i) doubling of degrees of freedom a la Schwinger-Keldysh, (ii) an emergent gauge U(1)T symmetry associated with entropy which is encapsulated in a Noether current a la Wald, and (iii) a BRST/topological supersymmetry imposing the fluctuation-dissipation theorem a la Parisi-Sourlas. The overarching mathematical framework for our construction is provided by the balanced equivariant cohomology of thermal translations, which captures the basic constraints arising from the Schwinger-Keldysh doubling, and the thermal Kubo-Martin-Schwinger relations. All these features are conveniently implemented in a covariant superspace formalism. An added benefit is that the second law can be understood as being due to entropy inflow from the Grassmann-odd directions of superspace.

Kubo formulas for thermodynamic transport coefficients

Uncharged relativistic fluids in 3+1 dimensions have three independent thermodynamic transport coefficients at second order in the derivative expansion. Fluids with a single global U(1) current have nine, out of which seven are parity preserving. We derive the Kubo formulas for all nine thermodynamic transport coefficients in terms of equilibrium correlation functions of the energy-momentum tensor and the current. All parity-preserving coefficients can be expressed in terms of two-point functions in flat space without external sources, while the parity-violating coefficients require three-point functions. We use the Kubo formulas to compute the thermodynamic coefficients in several examples of free field theories.

Peptide‐Based Multifunctional Nanomaterials for Tumor Imaging and Therapy

AbstractDuring the last decade, peptide‐based nanomaterials are recognized as upcoming biomedical materials for tumor imaging and therapy. The rapid expansion of peptides and peptide derivatives is almost owing to their excellent biocompatibility, diverse bioactivity, potential biodegradability, specific biological recognition ability, and easy chemical modification characteristic. The present review outlines the development up to now concerning the design and biomedical applications of peptide‐based multifunctional nanomaterials, with an emphasis on their variegated therapeutic methods.

Shape Sensitivity Analysis for Elastic Structures with Generalized Impedance Boundary Conditions of the Wentzell Type—Application to Compliance Minimization

This paper focuses on Generalized Impedance Boundary Conditions (GIBC) with second order derivatives in the context of linear elasticity and general curved interfaces. A condition of the Wentzell type modeling thin layer coatings on some elastic structure is obtained through an asymptotic analysis of order one of the transmission problem at the thin layer interfaces with respect to the thickness parameter. We prove the well-posedness of the approximate problem and the theoretical quadratic accuracy of the boundary conditions. Then we perform a shape sensitivity analysis of the GIBC model in order to study a shape optimization/optimal design problem. We prove the existence and characterize the first shape derivative of this model. A comparison with the asymptotic expansion of the first shape derivative associated to the original thin layer transmission problem shows that we can interchange the asymptotic and shape derivative analysis. Finally we apply these results to the compliance minimization problem. We compute the shape derivative of the compliance in this context and present some numerical simulations.

Large D holography with metric deformations

We consider Einstein gravity in AdS in the presence of a deformed conformal boundary metric, in the limit of large spacetime dimension. At leading order we find a new set of effective near-horizon equations. These can be understood as covariant generalisations of the undeformed equations with new source terms due to the curvature. We show that these equations are given by the conservation of the exact second-order Landau-frame hydrodynamic stress tensor. No derivative expansions are invoked in this identification. We use the new equations to study CFTs with 2d lattice deformations, computing their quasi-normal mode spectra and thermal conductivities, both numerically and analytically to quartic order in small lattice amplitude. Many of our results also apply to asymptotically flat spacetimes.

Reply to “Comment on ‘Relation between scattering amplitude and Bethe-Salpeter wave function in quantum field theory”’

We reemphasize the momentum dependence of the coefficients of the derivative expansion as already explained in our paper [1]. We also discuss how the momentum dependence plagues the time-dependent HALQCD method and what is a necessary condition for the method to yield valid results being independent of the choice of the interpolating operators.

On fractional Stieltjes constants

We study the non-integral generalized Stieltjes constants γα(a) arising from the Laurent series expansions of fractional derivatives of the Hurwitz zeta functions ζ(α)(s,a), and we prove that if ha(s)≔ζ(s,a)−1∕(s−1)−1∕as and Cα(a)≔γα(a)−logα(a)a, then Cα(a)=(−1)−αha(α)(1),for all real α≥0, where h(α)(x) denotes the α-th Grünwald–Letnikov fractional derivative of the function h at x. This result confirms the conjecture of Kreminski (2003), originally stated in terms of the Weyl fractional derivatives.

Causality of fluid dynamics for high-energy nuclear collisions

Dissipative relativistic fluid dynamics is not always causal and can favor super-luminal signal propagation under certain circumstances. On the other hand, high-energy nuclear collisions have a microscopic description in terms of QCD and are expected to follow the causality principle of special relativity. We discuss under which conditions the fluid evolution equations for a radial expansion are hyperbolic and that terms of second order in the Knudsen number are problematic for causality. We also outline briefly how this can be remedied with terms of higher order in a formal derivative expansion. The expansion dynamics are causal in the relativistic sense if the characteristic velocities are smaller than the speed of light. We obtain a concrete inequality from this constraint and discuss how it can be violated for certain initial conditions. Finally we argue that causality poses a bound on the applicability of relativistic fluid dynamics.

Decay rates f1(1285)→ρ0π+π− and a1(1260)→ωπ+π− in the Nambu–Jona-Lasinio model

The anomalous decays $f_1(1285)\to\rho^0\pi^+\pi^-$ and $a_1(1260)\to\omega\pi^+\pi^-$ violating natural parity for vectors and axial-vectors are studied in the framework of the Nambu -- Jona-Lasinio model. We consider the Lagrangian with $U(2)_L\times U(2)_R$ chiral symmetric four quark interactions. The theory is bosonized and corresponding effective meson vertices are obtained in the leading order of $1/N_c$ and derivative expansions. The uncertainties related with the surface terms of anomalous quark triangle diagrams are fixed by the corresponding symmetry requirements. We make a numerical estimate of the decay widths $\Gamma (f_1(1285)\to\rho^0\pi^+\pi^-)=2.78\, \mbox{MeV}$ and $\Gamma (a_1(1260)\to\omega\pi^+\pi^-)=87\, \mbox{keV}$. Our result on the $f_1(1285)\to\rho^0\pi^+\pi^-$ decay rate is in a good agreement with experiment. It is shown that a strong suppression of the $a_1(1260)\to\omega \pi\pi$ decay is a direct consequence of destructive interference between box and triangle anomalies.

Fractional conformable attractors with low fractality

In this paper, we considered a fractional conformable derivative of Liouville‐Caputo type of fractional‐order α=n−ϵ, which contains a small perturbation ϵ and positive integer n values between [0;1] to obtain the solutions of three different fractional conformable attractors (Chen's attractor, Genesio‐Tesi's attractor, and Liu's attractor). The fractional conformable Adomian decomposition method is applied to obtain an expansion of the fractional conformable derivative in ϵ=n−α. The solutions of the fractional chaotic systems are calculated in the form of convergent series. We investigate the dynamics of these attractors by numerical simulations for different fractional orders values and parameter ϵ.

Scaling solutions in the derivative expansion

Scalar field theories with $\mathbb{Z}_{2}$-symmetry are the traditional playground of critical phenomena. In this work these models are studied using functional renormalization group (FRG) equations at order $\partial^2$ of the derivative expansion and, differently from previous approaches, the spike plot technique is employed to find the relative scaling solutions in two and three dimensions. The anomalous dimension of the first few universality classes in $d=2$ is given and the phase structure predicted by conformal field theory is recovered (without the imposition of conformal invariance), while in $d=3$ a refined view of the standard Wilson-Fisher fixed point is found. Our study enlightens the strength of shooting techniques in studying FRG equations, suggesting them as candidates to investigate strongly non-perturbative theories even in more complex cases.

Flat holography and Carrollian fluids

We show that a holographic description of four-dimensional asymptotically locally flat spacetimes is reached smoothly from the zero-cosmological-constant limit of anti-de Sitter holography. To this end, we use the derivative expansion of fluid/gravity correspondence. From the boundary perspective, the vanishing of the bulk cosmological constant appears as the zero velocity of light limit. This sets how Carrollian geometry emerges in flat holography. The new boundary data are a two-dimensional spatial surface, identified with the null infinity of the bulk Ricci-flat spacetime, accompanied with a Carrollian time and equipped with a Carrollian structure, plus the dynamical observables of a conformal Carrollian fluid. These are the energy, the viscous stress tensors and the heat currents, whereas the Carrollian geometry is gathered by a two-dimensional spatial metric, a frame connection and a scale factor. The reconstruction of Ricci-flat spacetimes from Carrollian boundary data is conducted with a flat derivative expansion, resummed in a closed form in Eddington-Finkelstein gauge under further integrability conditions inherited from the ancestor anti-de Sitter set-up. These conditions are hinged on a duality relationship among fluid friction tensors and Cotton-like geometric data. We illustrate these results in the case of conformal Carrollian perfect fluids and Robinson-Trautman viscous hydrodynamics. The former are dual to the asymptotically flat Kerr-Taub-NUT family, while the latter leads to the homonymous class of algebraically special Ricci-flat spacetimes.

Quantum interactions of topological solitons from electrodynamics

The Casimir energy for the classically stable configurations of the topological solitons in 2D quantum antiferromagnets is studied by performing the path-integral over quantum fluctuations. The magnon fluctuation around the solitons saturating the Bogomol'nyi inequality may be viewed as a charged scalar field coupled with an effective magnetic field induced by the solitons. The magnon-soliton couping is closely related to the Pauli Hamiltonian, with which the effective action is calculated by adapting the worldline formulation of the derivative expansion for the 2+1d quantum electrodynamics in an external field. The resulting framework is more flexible than the conventional scattering analysis based on the Dashen-Hasslacher-Neveu formula. We obtain a short-range attractive well and a universal long-range $1/r$-type repulsive potential between two solitons.

Numerical Solution of the Bagley-Torvik Equation Using the Integer-Order Derivatives Expansion

Numerical solution of the well-known Bagley-Torvik equation is considered. The fractional-order derivative in the equation is converted, approximately, to ordinary-order derivatives up to second order. Approximated Bagley-Torvik equation is obtained using finite number of terms from the infinite series of integer-order derivatives expansion for the Riemann–Liouville fractional derivative. The Bagley-Torvik equation is a second-order differential equation with constant coefficients. The derived equation, by considering only the first three terms from the infinite series to become a second-order ordinary differential equation with variable coefficients, is numerically solved after it is transformed into a system of first-order ordinary differential equations. The approximation of fractional-order derivative and the order of the truncated error are illustrated through some examples. Comparison between our result and exact analytical solution are made by considering an example with known analytical solution to show the preciseness of our proposed approach.

Low-energy effective field theory of superfluid [formula omitted]He-B and its gyromagnetic and Hall responses

The low-energy physics of a superfluid 3He-B is governed by Nambu–Goldstone bosons resulting from its characteristic symmetry breaking pattern. Here we construct an effective field theory at zero temperature consistent with all available symmetries in curved space, which are the U(1)phase×SU(2)spin×SO(3)orbital gauge invariance and the nonrelativistic general coordinate invariance, up to the next-to-leading order in a derivative expansion. The obtained low-energy effective field theory is capable of reproducing gyromagnetic responses of the superfluid 3He-B, such as a magnetization generated by a rotation and an orbital angular momentum density generated by a magnetic field, in a model-independent and nonperturbative way. We furthermore show that the stress tensor exhibits a dissipationless Hall viscosity with coefficients uniquely fixed by the orbital angular momentum density, which manifests itself as an elliptical polarization of sound wave with an induced transverse component.