Notes

Examination of SARS-CoV-2 Seroprevalence simply by Community Survey as well as Left over Individuals, Denver, Denver, July-August 2020.
This low-mode asymmetry degrades hot-spot conditions at peak convergence and limits implosion performance and yield.Nanographenes with sublattice imbalance host a net spin according to Lieb's theorem for bipartite lattices. Here, we report the on-surface synthesis of atomically precise nanographenes and their atomic-scale characterization on a gold substrate by using low-temperature noncontact atomic force microscopy and scanning tunneling spectroscopy. Our results clearly confirm individual nanographenes host a single spin of S=1/2 via the Kondo effect. In covalently linked nanographene dimers, two spins are antiferromagnetically coupled with each other as revealed by inelastic spin-flip excitation spectroscopy. find more The magnetic exchange interaction in dimers can be well engineered by tuning the local spin density distribution near the connection region, consistent with mean-field Hubbard model calculations. Our work clearly reveals the emergence of magnetism in nanographenes and provides an efficient way to further explore the carbon-based magnetism.Noncovalent van der Waals (vdW) interactions are responsible for a wide range of phenomena in matter. Popular density-functional methods that treat vdW interactions use disparate physical models for these intricate forces, and as a result the applicability of these methods is often restricted to a subset of relevant molecules and materials. Aiming towards a general-purpose density functional model of vdW interactions, here we unify two complementary approaches nonlocal vdW functionals for polarization and interatomic methods for many-body interactions. The developed nonlocal many-body dispersion method (MBD-NL) increases the accuracy and efficiency of existing vdW functionals and is shown to be broadly applicable to molecules, soft and hard materials including ionic and metallic compounds, as well as interfaces between organic molecules and inorganic materials.Machine learning methods have proved to be useful for the recognition of patterns in statistical data. The measurement outcomes are intrinsically random in quantum physics, however, they do have a pattern when the measurements are performed successively on an open quantum system. This pattern is due to the system-environment interaction and contains information about the relaxation rates as well as non-Markovian memory effects. Here we develop a method to extract the information about the unknown environment from a series of projective single-shot measurements on the system (without resorting to the process tomography). The method is based on embedding the non-Markovian system dynamics into a Markovian dynamics of the system and the effective reservoir of finite dimension. The generator of Markovian embedding is learned by the maximum likelihood estimation. We verify the method by comparing its prediction with an exactly solvable non-Markovian dynamics. The developed algorithm to learn unknown quantum environments enables one to efficiently control and manipulate quantum systems.We study the three-body scattering hypervolume D of atoms whose scattering length a is on the order of or smaller than the typical range r_vdW of the van der Waals attraction. We find that the real part of D behaves universally in this weakly interacting regime (|a|/r_vdW≲1) in the absence of trimer resonances. This universality originates from hard-spherelike collisions that dominate elastic three-body scattering. We use this result to make quantitative predictions for the thermodynamics and elementary excitations of an atomic Bose-Einstein condensate in the vicinity of a quantum tricritical point, including quantum droplets stabilized by effective three-body interactions.We give a geometric interpretation of color-kinematics duality between tree-level scattering amplitudes of gauge and gravity theories. Using their representation as intersection numbers we show how to obtain Bern-Carrasco-Johansson numerators in a constructive way as residues around boundaries of the moduli space. In this language the kinematic Jacobi identity between each triple of numerators is a residue theorem in disguise.We investigate the dynamics of a Bose-Einstein condensate interacting with two noninterfering and counterpropagating modes of a ring resonator. Superfluid, supersolid, and dynamic phases are identified experimentally and theoretically. The supersolid phase is obtained for sufficiently equal pump strengths for the two modes. In this regime we observe the emergence of a steady state with crystalline order, which spontaneously breaks the continuous translational symmetry of the system. The supersolidity of this state is demonstrated by the conservation of global phase coherence at the superfluid to supersolid phase transition. Above a critical pump asymmetry the system evolves into a dynamic runaway instability commonly known as collective atomic recoil lasing. We present a phase diagram and characterize the individual phases by comparing theoretical predictions with experimental observations.We report observation of electric field driven conductivity with negative differential conductance and resistive switching in insulating SrTiO_3 samples over a wide range of applied voltages at low temperatures. The observed current follows I=I_0exp[-(E^*/E)^1/2] at large applied electric field, corresponding to variable range hopping conduction with a Coulomb gap in domain walls. Our data are sufficient to discriminate unambiguously between Shklovskii and Mott hopping via their different electric field exponent. Under some conditions space-charge-limited currents are observed, and the charge mobility limit is determined to be in the range of 17 and 210  cm^2/Vs.Neutrinos produced in the hot and dense interior of the next galactic supernova would be visible at dark matter experiments in coherent elastic nuclear recoils. While studies on this channel have focused on successful core-collapse supernovae, a thermonuclear (type Ia) explosion, or a core collapse that fails to explode and forms a black hole, are as likely to occur as the next galactic supernova event. I show that generation-3 noble liquid-based dark matter experiments such as darwin and argo, operating at sub-keV thresholds with ionization-only signals, would distinguish between (a) leading hypotheses of type Ia explosion mechanisms by detecting an O(1)  s burst of O(1)  MeV neutrinos, and (b) progenitor models of failed supernovae by detecting an O(1)  s burst of O(10)  MeV neutrinos, especially by marking the instant of black hole formation from abrupt stoppage of neutrino detection. This detection is sensitive to all neutrino flavors and insensitive to neutrino oscillations, thereby making measurements complementary to neutrino experiments.This corrects the article DOI 10.1103/PhysRevLett.114.166101.We study the phase diagram of a one-dimensional version of the Kitaev spin-1/2 model with an extra "Γ term," using analytical, density matrix renormalization group and exact diagonalization methods. Two intriguing phases are found. In the gapless phase, although the exact symmetry group of the system is discrete, the low energy theory is described by an emergent SU(2)_1 Wess-Zumino-Witten (WZW) model. On the other hand, the spin-spin correlation functions exhibit SU(2) breaking prefactors, even though the exponents and the logarithmic corrections are consistent with the SU(2)_1 predictions. A modified non-Abelian bosonization formula is proposed to capture such exotic emergent "partial" SU(2) symmetry. In the ordered phase, there is numerical evidence for an O_h→D_4 spontaneous symmetry breaking.We report an ingenious mechanism to obtain robust optical pulling force by a single plane wave via engineering the topology of light momentum in the background. The underlying physics is found to be the topological transition of the light momentum from a usual convex shape to a starlike concave shape in the carefully designed background, such as a photonic crystal structure. The principle and results reported here shed insightful concepts concerning optical pulling, and pave the way for a new class of advanced optical manipulation technique, with potential applications of drug delivery and cell sorting.Pronounced anomalies in the SrTiO_3 dynamical structure factor, S(Q,E), including the disappearance of acoustic phonon branches at low temperatures, were uncovered with inelastic neutron scattering (INS) and simulations. The striking effect reflects anharmonic couplings between acoustic and optic phonons and the incipient ferroelectric instability near the quantum critical point. It is rationalized using a first-principles renormalized anharmonic phonon approach, pointing to nonlinear Ti-O hybridization causing unusual changes in real-space phonon eigenvectors, frequencies, group velocities, and scattering phase space. Our method is general and establishes how T dependences beyond the harmonic regime, assessed by INS mapping of large reciprocal-space volumes, provide real-space insights into anharmonic atomic dynamics near phase transitions.Density-functional theory is used to explore the Si(553)-Au surface dynamics. Our study (i) reveals a complex two-stage order-disorder phase transition where with rising temperature first the ×3 order along the Si step edges and, subsequently, the ×2 order of the Au chains is lost, (ii) identifies the transient modification of the electron chemical potential during soft Au chain vibrations as instrumental for disorder at the step edge, and (iii) shows that the transition leads to a self-doping of the Si dangling-bond wire at the step edge. The calculations are corroborated by Raman measurements of surface phonon modes and explain previous electron diffraction, scanning tunneling microscopy, and surface transport data.By combining molecular dynamics simulations and topological analyses with scaling arguments, we obtain analytic expressions that quantitatively predict the entanglement length N_e, the plateau modulus G, and the tube diameter a in melts that span the entire range of chain stiffnesses for which systems remain isotropic. Our expressions resolve conflicts between previous scaling predictions for the loosely entangled [Lin-Noolandi, Gℓ_K^3/k_BT∼(ℓ_K/p)^3], semiflexible [Edwards-de Gennes Gℓ_K^3/k_BT∼(ℓ_K/p)^2], and tightly entangled [Morse, Gℓ_K^3/k_BT∼(ℓ_K/p)^1+ϵ] regimes, where ℓ_K and p are, respectively, the Kuhn and packing lengths. We also find that maximal entanglement (minimal N_e) coincides with the onset of local nematic order.We study evolution of self-interacting dark matter subhalos in the Milky Way tidal field. The interaction between the subhalos and the Milky Way's tides lead to more diverse dark matter distributions in the inner region, compared to their cold dark matter counterparts. We test this scenario with two Milky Way satellite galaxies, Draco and Fornax, opposite extremes in the inner dark matter content, and find that they can be accommodated within the self-interacting dark matter model proposed to explain the diverse rotation curves of spiral galaxies in the field.
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