Nonlocal Contributions Research Articles

Optimal work associated with off-centered harmonic Brownian motion at any friction damping.

There is extensive literature on how to determine the work involving a Brownian particle interacting with an external field and submerged in a thermal reservoir. However, the information supplied is essentially theoretical without specific calculations to show how this property changes with the system parameters and initial conditions. In this article, we provide explicit calculations of the optimal work considering the particle is under the influence of a time-dependent off-centered moving harmonic potential. It is done for all physical values of the friction coefficient. The system is modeled through a more general version of the Langevin equation which encompasses its classical and quasiclassical version. From the equation that defines the work, the external protocol is found through a fairly current extended version of the Euler-Lagrange equation that unifies the local and nonlocal contributions in a simple expression. The protocol is linear and, unlike previous work, not only changes the initial velocity of the particle but also its acceleration. Calculations were done for friction constants γ spanning all possible values. The periodic γ=1 shows discontinuities in the optimal work of the interplay of concentration and diffusion processes acting periodically in the dynamics. For higher values work appears to be as a smooth function of time, while the truly overdamped, where the inertial effect can be discarded, agrees with the analytical result up to a time where the numerical overdamped algorithm provides a different solution due to its inability to discard entirely the inertial effect.

Determination of local traffic emission and non-local background source contribution to on-road air pollution using fixed-route mobile air sensor network

Traffic-related air pollutants are major contributors to deteriorating urban air quality and pose a serious threat to pedestrians. From both a scientific and a regulatory standpoint, it is important and challenging to understand the contributions of local and non-local sources to accurately apportion specific sources such as traffic emissions contribution to on-road and near-road microenvironment air quality. In this study, we deployed mobile sensors on-board buses to monitor NO, NO2, CO and PM2.5 along ten important routes in Hong Kong. The measurements include two seasons: April 2017 and July 2017. Two types of baseline extraction methods were evaluated and applied to separate local and background concentrations. The results show NO and NO2 are locally dominated air pollutants in spring, constituting 72%–84% and 58%–71%, respectively, with large inter-road variation. PM2.5 and CO largely arise from background sources, which contribute 55%–65% and 73%–79% respectively. PM2.5 displays a homogeneous spatial pattern, and the contributions show seasonal change, decreasing during summer. Regional transport pollution is the primary contributor during high pollution episodes. Isolated vehicle plumes show highly skewed concentration distributions. There are characteristic polluted segments on routes and they are most evident at rush hours. The most polluted road segments (top 10%) cluster at tunnel entrances and congested points. Some of these polluted locations were observed in Hong Kong's Low Emission Zones and suggest limitations to the existing control strategies, which only address larger buses. Our work gives new insights in the importance of regional cooperation to improve background air pollution combined with local control strategies to improve roadside air quality in Hong Kong.

Generating Spin Polarization from Vorticity through Nonlocal Collisions

We derive the collision term in the Boltzmann equation using the equation of motion for the Wigner function of massive spin-1/2 particles. To next-to-lowest order in ℏ, it contains a nonlocal contribution, which is responsible for the conversion of orbital into spin angular momentum. In a proper choice of pseudogauge, the antisymmetric part of the energy-momentum tensor arises solely from this nonlocal contribution. We show that the collision term vanishes in global equilibrium and that the spin potential is, then, equal to the thermal vorticity. In the nonrelativistic limit, the equations of motion for the energy-momentum and spin tensors reduce to the well-known form for hydrodynamics for micropolar fluids.

Structural Changes beyond the EF-Hand Contribute to Apparent Calcium Binding Affinities: Insights from Parvalbumins.

Members of the parvalbumin (PV) family of calcium (Ca2+) binding proteins (CBPs) share a relatively high level of sequence similarity. However, their Ca2+ affinities and selectivities against competing ions like Mg2+ can widely vary. We conducted molecular dynamics simulations of several α-parvalbumin (αPV) constructs with micromolar to nanomolar Ca2+ affinities to identify structural and dynamic features that contribute to their binding of ions. Specifically, we examined a D94S/G98E construct with a lower Ca2+ affinity (≈-18 kcal/mol) relative to the wild type (WT) (≈-22 kcal/mol) and an S55D/E59D variant with enhanced affinity (≈-24 kcal/mol). Additionally, we also examined the binding of Mg2+ to these isoforms, which is much weaker than Ca2+. We used mean spherical approximation (MSA) theory to evaluate ion binding thermodynamics within the proteins' EF-hand domains to account for the impact of ions' finite sizes and the surrounding electrolyte composition. While the MSA scores differentiated Mg2+ from Ca2+, they did not indicate that Ca2+ binding affinities at the binding loop differed between the PV isoforms. Instead, molecular mechanics generalized Born surface area (MM/GBSA) approximation energies, which we used to quantify the thermodynamic cost of structural rearrangement of the proteins upon binding ions, indicated that S55D/E59D αPV favored Ca2+ binding by -20 kcal/mol relative to WT versus 30 kcal/mol for D94S/G98E αPV. Meanwhile, Mg2+ binding was favored for the S55D/E59D αPV and D94S/G98E αPV variants by -18.32 and -1.65 kcal/mol, respectively. These energies implicate significant contributions to ion binding beyond oxygen coordination at the binding loop, which stemmed from changes in α-helicity, β-sheet character, and hydrogen bonding. Hence, Ca2+ affinity and selectivity against Mg2+ are emergent properties stemming from both local effects within the proteins' ion binding sites as well as non-local contributions elsewhere. Our findings broaden our understanding of the molecular bases governing αPV ion binding that are likely shared by members of the broad family of CBPs.

Inflaton effective potential from photons for general ε

We accurately approximate the contribution that photons make to the effective potential of a charged inflaton for inflationary geometries with an arbitrary first slow roll parameter $\epsilon$. We find a small, nonlocal contribution and a numerically larger, local part. The local part involves first and second derivatives of $\epsilon$, coming exclusively from the constrained part of the electromagnetic field which carries the long range interaction. This causes the effective potential induced by electromagnetism to respond more strongly to geometrical evolution than for either scalars, which have no derivatives, or spin one half particles, which have only one derivative. For $\epsilon = 0$ our final result agrees with that of Allen on de Sitter background, while the flat space limit agrees with the classic result of Coleman and Weinberg.

Limit behaviour of Eringen’s two-phase elastic beams

In this paper, the bending behaviour of small-scale Bernoulli–Euler beams is investigated by Eringen’s two-phase local/nonlocal theory of elasticity. Bending moments are expressed in terms of elastic curvatures by a convex combination of local and nonlocal contributions, that is a combination with non-negative scalar coefficients summing to unity. The nonlocal contribution is the convolution integral of the elastic curvature field with a suitable averaging kernel characterized by a scale parameter. The relevant structural problem, well-posed for non-vanishing local phases, is preliminarily formulated and exact elastic solutions of some simple beam problems are recalled. Limit behaviours of the obtained elastic solutions, analytically evaluated, studied and diagrammed, do not fulfil equilibrium requirements and kinematic boundary conditions. Accordingly, unlike alleged claims in literature, such asymptotic fields cannot be assumed as solutions of the purely nonlocal theory of beam elasticity. This conclusion agrees with the known result which the elastic equilibrium problem of beams of engineering interest formulated by Eringen’s purely nonlocal theory admits no solution.

Spatial locality of electronic correlations in LiFeAs

We address the question of the degree of spatial non-locality of the self energy in the iron-based superconductors, a subject which is receiving considerable attention. Using LiFeAs as a prototypical example, we extract the self energy from angular-resolved photoemission spectroscopy (ARPES) data. We use two distinct electronic structure references: density functional theory in the local density approximation and linearized quasiparticle self consistent GW (LQSGW). We find that with the LQSGW reference, spatially local dynamical correlations provide a consistent description of the experimental data, and account for some surprising aspects of the data such as the substantial out of plan dispersion of the electron Fermi surface having dominant xz/yz character. Hence, correlations effects can be separated into static non-local contributions well described by LQSGW and dynamical local contributions. Hall effect and resistivity data are shown to be consistent with this description.

Exchange effects in nucleus-nucleus reactions

We present a scattering model for nuclei with similar masses. In this three-body model, the projectile has a core+valence structure, whereas the target is identical to the core nucleus. The three-body wave functions must be symmetrized for the exchange of the cores. This property gives rise to non-local potentials, which are computed without approximation. The present model is an extension of the Continuum Discretized Coupled Channel (CDCC) formalism, with an additional treatment of core exchange. We solve the coupled-channel system, including non-local terms, by the $R$-matrix method using Lagrange functions. This model is applied to the $^{13}{\rm C}+^{12}$C, $^{13}{\rm N}+^{12}$C and $^{16}{\rm O}+^{12}$C systems. Experimental scattering cross sections are fairly well reproduced without any parameter fitting. The backward-angle enhancement of the elastic cross sections is due to the non-local potential. We discuss in more detail the various non-local contributions and present effective local potentials.

Quantification of Regional Ozone Pollution Characteristics and Its Temporal Evolution: Insights from Identification of the Impacts of Meteorological Conditions and Emissions

Ozone (O3) pollution has become the major new challenge after the suppression of PM2.5 to levels below the standard for the Pearl River Delta (PRD). O3 can be transported between nearby stations due to its longevity, leading stations with a similar concentration in a state of aggregation, which is an alleged regional issue. Investigations in such regional characteristics were rarely involved ever. In this study, the aggregation (reflected by the global Moran’s I index, GM), its temporal evolution, and the impacts from meteorological conditions and both local (i.e., produced within the PRD) and non-local (i.e., transported from outside the PRD) contributions were explored by spatial analysis and statistical modeling based on observation data. The results from 2007 to 2018 showed that the GM was positive overall, implying that the monitoring stations were surrounded by stations with similar ozone levels, especially during ozone seasons. State of aggregation was reinforced from 2007 to 2012, and remained stable thereafter. Further investigations revealed that GM values were independent of meteorological conditions, while closely related to local and non-local contributions, and its temporal variations were driven only by local contributions. Then, the correlation (R2) between O3 and meteorology was identified. Result demonstrated that the westerly belonged to temperature (T) and surface solar radiation (SSR) sensitive regions and the correlation between ozone and the two became intense with time. Relative humidity (RH) showed a negative correlation with ozone in most areas and periods, whereas correlations with u and v were positive for northerly winds and negative for southerly winds. Two important key points of such investigation are that, firstly, we defined the features of ozone pollution by characterizing the temporal variations in spatial discrepancies among all stations, secondly, we highlighted the significance of subregional cooperation within the PRD and regional cooperation with external environmental organizations.

The turbulent bubble break-up cascade. Part 1. Theoretical developments

Abstract

Fermionic degeneracy and non-local contributions in flag-dipole spinors and mass dimension one fermions

We construct a mass dimension one fermionic field associated with flag-dipole spinors. These spinors are related to Elko (flag-pole spinors) by a one-parameter matrix transformation {mathcal {Z}}(z) where z is a complex number. The theory is non-local and non-covariant. While it is possible to obtain a Lorentz-invariant theory via tau -deformation, we choose to study the effects of non-locality and non-covariance. Our motivation for doing so is explained. We show that a fermionic field with |z|ne 1 and |z|=1 are physically equivalent. But for fermionic fields with more than one value of z, their interactions are z-dependent thus introducing an additional fermionic degeneracy that is absent in the Lorentz-invariant theory. We study the fermionic self-interaction and the local U(1) interaction. In the process, we obtained non-local contributions for fermionic self-interaction that have previously been neglected. For the local U(1) theory, the interactions contain time derivatives that renders the interacting density non-commutative at space-like separation. We show that this problem can be resolved by working in the temporal gauge. This issue is also discussed in the context of gravity.

Spin Nernst and anomalous Nernst effects and their signature outputs in ferromagnet/nonmagnet heterostructures

The spin Nernst effect (SNE) and anomalous Nernst effect (ANE) convert a heat current generated by a temperature gradient to a spin current in nonmagnetic metals and ferromagnets, respectively. We present a diffusive spin transport theory of the combination of these thermoelectric effects in ferromagnet (F)/nonmagnet (N) heterostructures and their respective output signals. In a F/N bilayer, in the presence of an in-plane temperature gradient, electrical voltages are induced by the SNE in N and the ANE in the F layers, via the inverse spin Hall effect in the N. The analytical expression of the thermally driven spin Hall magnetoresistance (TSMR) output is derived, which captures both the local SNE contribution in the N and the nonlocal mixing contribution due to the ANE in the adjacent F. Interestingly, the SNE and ANE give additive contributions to the transverse TSMR voltages but subtract from each other for the longitudinal component. This anisotropic response suggests a possible means to extract the individual SNE and ANE contributions, as well as spin-dependent polarization parameters. In a F1/N/F2 trilayer, both SNE and ANE contribute to spin torques on the free F2 layer. We analyze the ferromagnetic resonance (FMR) of the free layer and show that both thermoelectric effects contribute additively to the FMR magnitude and linewidth for the considered magnetization configuration. Finally, we show that TSMR can provide a more sensitive experimental detection of SNE and ANE down to a threshold thermal gradient of the order of ${10}^{\ensuremath{-}6}$ K/nm.

Exploring a near-Hartree-Fock-Kohn-Sham approach to study electronic properties of azobenzene in interaction with gold: From clusters to the Au(111) surface.

The electronic properties of azobenzene (AB) in interaction with gold clusters and adsorbed on the Au(111) surface are investigated by adopting a near-Hartree-Fock-Kohn-Sham (HFKS) scheme. This scheme relies on a hybrid Perdew-Burke-Ernzerhof functional, in which the exact non-local HF exchange contribution to the energy is taken as 3/4. Ionization energies and electron affinities for gas phase AB are in very good agreement with experimental data and outer valence Green's function) calculations. The presence of C-H⋯Au interactions in AB-Aun complexes illustrates the role played by weak interactions between molecular systems and Au nanoparticles, which is in line with recent works on Au-H bonding. In AB-Aun complexes, the frontier orbitals are mainly localized on the gold platform when n ≥ 10, which indicates the transition from a molecular to a semiconducting regime. In the latter regime, the electronic density reorganization in AB-Aun clusters is characterized by significant polarization effects on the Au platform. The accuracy of the near-HFKS scheme for predicting adsorption energies of AB on Au(111) and the interest of combining exact non-local HF exchange with a non-local representation of the dispersion energy are discussed. Taking into account the significant computational cost of the exact non-local HF exchange contribution, calculations for the adsorption energies and density of states for AB adsorbed on Au(111) were carried out by using a quantum mechanics/molecular mechanics approach. The results strongly support near-HFKS as a promising methodology for predicting the electronic properties of hybrid organic-metal systems.

Self-attenuation of extreme events in Navier\u2013Stokes turbulence

Turbulent fluid flows are ubiquitous in nature and technology, and are mathematically described by the incompressible Navier-Stokes equations. A hallmark of turbulence is spontaneous generation of intense whirls, resulting from amplification of the fluid rotation-rate (vorticity) by its deformation-rate (strain). This interaction, encoded in the non-linearity of Navier-Stokes equations, is non-local, i.e., depends on the entire state of the flow, constituting a serious hindrance in turbulence theory and even establishing regularity of the equations. Here, we unveil a novel aspect of this interaction, by separating strain into local and non-local contributions utilizing the Biot-Savart integral of vorticity in a sphere of radius R. Analyzing highly-resolved numerical turbulent solutions to Navier-Stokes equations, we find that when vorticity becomes very large, the local strain over small R surprisingly counteracts further amplification. This uncovered self-attenuation mechanism is further shown to be connected to local Beltramization of the flow, and could provide a direction in establishing the regularity of Navier-Stokes equations.

Revisiting radiative leptonic B decay * *Y.B.W is Supported in part by the National Natural Science Foundation of China (NSFC) (11675082, 11735010)

In this paper, we summarize the existing methods of solving the evolution equation of the leading-twist B-meson LCDA. Then, in the Mellin space, we derive a factorization formula with next-to-leading-logarithmic (NLL) resummation for the form factors in the decay at leading power in . Furthermore, we investigate the power suppressed local contributions, factorizable non-local contributions (which are suppressed by and ), and soft contributions to the form factors. In the numerical analysis, which employs the two-loop-level hard function and the jet function, we find that both the resummation effect and the power corrections can sizably decrease the form factors. Finally, the integrated branching ratios are also calculated for comparison with future experimental data.

Regional and Sectoral Sources for Black Carbon Over South China in Spring and Their Sensitivity to East Asian Summer Monsoon Onset

AbstractBesides local emissions, biomass burning (BB) emissions in peninsula Southeast Asia (PSEA) and domestic anthropogenic emissions in North China (NC) are also significant black carbon (BC) sources over South China (SC) in spring. Meanwhile, the East Asian summer monsoon (EASM) is established with the wind field reversal, influencing the region‐based contributions to BC over SC. Herein, BC sources for SC were tracked by region and by sector using the Community Earth System Model with a BC‐tagging technique. During the spring of 2000–2014, 27% of BC surface concentration (BCS) and 64% of BC column burden (BCC) over SC stems from nonlocal sources. BC from NC is mainly transported below 850 hPa. It is the dominant nonlocal contribution to BCS (17%) and largely composed of residential and industrial sectors. Nonlocal emissions inside and outside China contribute 28% and 36% to BCC, respectively. Generally transported above 850 hPa, BC from PSEA is the largest nonlocal contributor (20%) to BCC and contributes 80% of BCC in BB sector. Additionally, the interannual variation in EASM onset times bring a maximum of −5% to +7%/−2% to +7% variation in BCC/BCS. The BC outflow/inflow contributed from NC dominates the BC decrease/increase over SC with southerly/northerly wind anomaly induced by early/late EASM onset, yet regional transport from PSEA contributes minor BC changes. The simulated BC is significantly positively correlated with the varying EASM onset times, but not with emissions, indicating the decisive role of meteorology in the interannual variation of BC over SC during springtime.

An Eddy‐Diffusivity Mass‐Flux Parameterization for Modeling Oceanic Convection

AbstractA new one‐dimensional (1‐D) parameterization of penetrative convection has been developed in order to have a better representation of the vertical mixing in ocean general circulation models. Our approach is inspired from atmospheric parameterizations of shallow convection which assumes that in the convective boundary layer, the subgrid‐scale fluxes result from two different mixing scales: small eddies, which are represented by an Eddy‐Diffusivity (ED) contribution, and large eddies associated with thermals, which are represented by a mass‐flux contribution. In the present work, the local (small eddies) and nonlocal (large eddies) contributions are unified into an Eddy‐Diffusivity‐Mass‐Flux (EDMF) parameterization which treats simultaneously the whole vertical mixing. EDMF is implemented in the community ocean model NEMO and tested in its 1‐D column version. Deepening of dense water in analytic cases, successfully reproduced in LES simulations, is more realistic with EDMF than with standard diffusion parameterizations. Also the convective events observed in the western Mediterranean at the Lion station and in the North Pacific Ocean at the PAPA station are more realistic in terms of sequencing and amplitude with EDMF.

Transport Features in the Topological Phase Hg0.87Cd0.13Te under Terahertz Photoexcitation

In this paper, we report on photoconductivity induced by high-power laser radiation with a frequency of 2 THz in Hg0.87Cd0.13Te-based epitaxial structures. Experimental results obtained for a set of the samples with variable geometric parameters allow us to determine the photoresponse features of both bulk and nonlocal contributions to the net response. We show that the persistent photoconductivity effect originates from the non-equilibrium processes related to the bulk carrier excitation.

Quantitative and qualitative performance of density functional theory rationalized by reduced density gradient distributions

We evaluate the qualitative and quantitative accuracy of various flavors of density functionals with and without accounting for dispersion corrections. Our test system is nickel in the form of bulk, surfaces, and nanoparticles for which we compute structural properties, bulk cohesive energies, surface energies, and work functions and compare to experimental data. We find that the inclusion of any dispersion, either by an a posteriori correction or by a self-consistent treatment by explicitly computing the nonlocal correlation contribution to the total energy, has a significant effect on the calculated properties and improves the quantitative comparison to experiments. Besides the quantitative agreement, we also investigate qualitative features by comparing Wulff shapes of metal nanoparticles as obtained using the different density functionals. We find that all tested functionals predict similar Wulff shapes for nickel nanoparticles but still have some small differences. These results show that the relative energies calculated using the semilocal GGA and meta-GGA functionals, with and without dispersion, are quite similar. Our findings can also be generalized to other systems when rationalized in terms of the computed reduced density gradients. We find that the distribution of reduced density gradients in a material is correlated to the steepness of the exchange enhancement factor and propose that this information can be used as a quantitative guide when it comes to picking the most appropriate density functional for specific target systems as well as when it comes to extrapolating DFT data to predict experiments.

Binary dynamics at the fifth and fifth-and-a-half post-Newtonian orders

Using the new methodology introduced in a recent Letter [Phys.\ Rev.\ Lett.\ {\bf 123}, 231104 (2019)], we present the details of the computation of the conservative dynamics of gravitationally interacting binary systems at the fifth post-Newtonian (5PN) level, together with its extension at the fifth-and-a-half post-Newtonian (5.5PN) level. We present also the sixth post-Newtonian (6PN) contribution to the third-post-Minkowskian (3PM) dynamics. Our strategy combines several theoretical formalisms: post-Newtonian, post-Minkowskian, multipolar-post-Minkowskian, gravitational self-force, effective one-body, and Delaunay averaging. We determine the full functional structure of the 5PN Hamiltonian (which involves 95 non-zero numerical coefficients), except for two undetermined coefficients proportional to the cube of the symmetric mass ratio, and to the fifth and sixth power of the gravitational constant, $G$. We present not only the 5PN-accurate, 3PM contribution to the scattering angle, but also its 6PN-accurate generalization. Both results agree with the corresponding truncations of the recent 3PM result of Bern et al. [Phys.\ Rev.\ Lett.\ {\bf 122}, 201603 (2019)]. We also compute the 5PN-accurate, fourth-post-Minkowskian (4PM) contribution to the scattering angle, including its nonlocal contribution, thereby offering checks for future 4PM calculations. We point out a remarkable hidden simplicity of the gauge-invariant functional relation between the radial action and the effective-one-body energy and angular momentum.