Nonparametric Markovian Learning of Triggering Kernels for Mutually Exciting and Mutually Inhibiting Multivariate Hawkes Processes

In this paper, we address the problem of fitting multivariate Hawkes processes to potentially large-scale data in a setting where series of events are not only mutually-exciting but can also exhibit inhibitive patterns. We focus on nonparametric learning and propose a novel algorithm called MEMIP (Markovian Estimation of Mutually Interacting Processes) that makes use of polynomial approximation theory and self-concordant analysis in order to learn both triggering kernels and base intensities of events. Moreover, considering that N historical observations are available, the algorithm performs log-likelihood maximization in $O(N)$ operations, while the complexity of non-Markovian methods is in $O(N^{2})$. Numerical experiments on simulated data, as well as real-world data, show that our method enjoys improved prediction performance when compared to state-of-the art methods like MMEL and exponential kernels

Continuum-discretized coupled-channels method for four-body breakup reactions

Development of the method of CDCC (Continuum-Discretized Coupled-Channels) from the level of three-body CDCC to that of four-body CDCC is reviewed. Introduction of the pseudo-state method based on the Gaussian expansion method for discretizing the continuum states of two-body and three-body projectiles plays an essential role in the development. Furthermore, introduction of the complex-range Gaussian basis functions is important to improve the CDCC for nuclear breakup so as to accomplish that for Coulomb and nuclear breakup. A successful application of the four-body CDCC to $^6$He+$^{12}$C scattering at 18 and 229.8 MeV is reported.Comment: Latex file of revtex4 class, 14 pages, 10 figures. A talk given at the Workshop on Reaction Mechanisms for Rare Isotope Beams, Michigan State University, March 9-12, 2005 (to appear in an AIP Conference Proceedings

Propagation of Correlations in Quantum Lattice Systems

We provide a simple proof of the Lieb-Robinson bound and use it to prove the existence of the dynamics for interactions with polynomial decay. We then use our results to demonstrate that there is an upper bound on the rate at which correlations between observables with separated support can accumulate as a consequence of the dynamics.Comment: 10 page

The Brieva-Rook Localization of the Microscopic Nucleon-Nucleus Potential

The nonlocality of the microscopic nucleon-nucleus optical potential is commonly localized by the Brieva-Rook approximation. The validity of the localization is tested for the proton+$^{90}$Zr scattering at the incident energies from 65 MeV to 800 MeV. The localization is valid in the wide incident-energy range.Comment: 20 pages, 8 figure

Continuum-discretized coupled-channels method for four-body nuclear breakup in 6^6He+12^{12}C scattering

We propose a fully quantum-mechanical method of treating four-body nuclear breakup processes in scattering of a projectile consisting of three constituents, by extending the continuum-discretized coupled-channels method. The three-body continuum states of the projectile are discretized by diagonalizing the internal Hamiltonian of the projectile with the Gaussian basis functions. For $^6$He+$^{12}$C scattering at 18 and 229.8 MeV, the validity of the method is tested by convergence of the elastic and breakup cross sections with respect to increasing the number of the basis functions. Effects of the four-body breakup and the Borromean structure of $^6$He on the elastic and total reaction cross sections are discussed.Comment: 5 pages, 6 figures, uses REVTeX 4, submitted to Phys. Rev.

Asynchronous Graph Pattern Matching on Multiprocessor Systems

Pattern matching on large graphs is the foundation for a variety of application domains. Strict latency requirements and continuously increasing graph sizes demand the usage of highly parallel in-memory graph processing engines that need to consider non-uniform memory access (NUMA) and concurrency issues to scale up on modern multiprocessor systems. To tackle these aspects, graph partitioning becomes increasingly important. Hence, we present a technique to process graph pattern matching on NUMA systems in this paper. As a scalable pattern matching processing infrastructure, we leverage a data-oriented architecture that preserves data locality and minimizes concurrency-related bottlenecks on NUMA systems. We show in detail, how graph pattern matching can be asynchronously processed on a multiprocessor system.Comment: 14 Pages, Extended version for ADBIS 201

The Phase Diagram of Correlated Electrons in a Lattice of Berry Molecules

A model for correlated electrons in a lattice with local additional spin--1 degrees of freedom inducing constrained hopping, is studied both in the low density limit and at quarter filling. We show that in both 1D and 2D two particles form a bound state even in presence of a repulsive U<U_c. A picture of a dilute Bose gas, leading to off-diagonal long range order (LRO) in 2D (quasi-LRO in 1D), is supported by quantitative calculations in 1D which allow for a determination of the phase diagram.Comment: 7 pages + 2 ps figures, published versio

Transport dynamics of self-consistent, near-marginal drift-wave turbulence. I. Investigation of the ability of external flows to tune the non-diffusive dynamics

The reduction of turbulent transport across sheared flow regions has been known for a long time in magnetically confined toroidal plasmas. However, details of the dynamics are still unclear, in particular, in what refers to the changes caused by the flow on the nature of radial transport itself. In Paper II, we have shown in a simplified model of drift wave turbulence that, when the background profile is allowed to evolve self-consistently with fluctuations, a variety of transport regimes ranging from superdiffusive to subdiffusive open up depending on the properties of the underlying turbulence [D. Ogata et al., Phys. Plasmas 24, 052307 (2017)]. In this paper, we show that externally applied sheared flows can, under the proper conditions, cause the transport dynamics to be diffusive or subdiffusive.This work was supported by U.S. DOE Contract No. DE-FG02-04ER54741 with the University of Alaska Fairbanks and in part by a grant of HPC resources from the Arctic Region Supercomputing Center at the University of Alaska Fairbanks. This research was also sponsored in part by DGICYT (Dirección General de Investigaciones Científicas y Tecnológicas) of Spain under Project No. ENE2015-68265

Bunchy top disease of bananas

Short publication describing symptoms and control of banana bunchy top disease

Correlation between Superconducting Transition Temperature TcT_c and Increase of Nuclear Spin-Lattice Relaxation Rate Devided by Temperature 1/T1T1/T_1T at TcT_c in the Hydrate Cobaltate Nax_{x}CoO2⋅y_{2}\cdot yH2_{2}O

We have performed Co-nuclear quadrupole resonance (NQR) studies on Na$_{x}$CoO$_{2}\cdot y$H$_{2}$O compounds with different Na ($x$) and hydrate ($y$) contents. Two samples with different Na contents but nearly the same $T_c$ values ($x$ = 0.348, $T_c$ = 4.7 K ; $x$ = 0.339, $T_c$ = 4.6 K) were investigated. The spin-lattice relaxation rate $1/T_1$ in the superconducting (SC) and normal states is almost the same for the two samples except just above $T_c$. NQR measurements were also performed on different-hydrate-content samples with different $T_c$ values, which were prepared from the same Na-content ($x$ = 0.348) sample. From measurements of $1/T_1$ using the different-hydrate-content samples, it was found that a low-$T_c$ sample with $T_c = 3.9$ K has a larger residual density of states (DOS) in the SC state and a smaller increase of $1/T_1T$ just above $T_c$ than a high-$T_c$ sample with $T_c$ = 4.7 K. The former behavior is consistent with that observed in unconventional superconductors, and the latter suggests the relationship between $T_c$ and the increase in DOS just above $T_c$. This increase, which is seemingly associated with the two-dimensionality of the CoO$_2$ plane, is considered to be one of the most important factors for the occurrence of superconductivity.Comment: 5 pages, 5 figures, To be published in J. Phys. Soc. Jp