Comparison of the color-evaporation model and the NRQCD factorization approach in charmonium production

We compare the color-evaporation model (CEM) and nonrelativistic QCD (NRQCD) factorization predictions for inclusive quarkonium production. Using the NRQCD factorization formulas for quarkonium production and for perturbative QQ-bar production, we deduce relationships that are implied by the CEM between the nonperturbative NRQCD matrix elements that appear in the factorization formula for quarkonium production. These relationships are at odds with the phenomenological values of the matrix elements that have been extracted from the Tevatron data for charmonium production at large transverse momentum. A direct comparison of the CEM and NRQCD factorization predictions with the CDF charmonium production data reveals that the CEM fits to the data are generally unsatisfactory, while the NRQCD factorization fits are generally compatible with the data. The inclusion of k_T smearing improves the CEM fits substantially, but significant incompatibilities remain. The NRQCD factorization fits to the chi_c data indicate that multiple gluon radiation is an essential ingredient in obtaining the correct shape of the cross section as a function of p_T.Comment: 26 pages, 6 figures, 7 tables, Some changes of emphasis in the conclusions, additional discussion of theoretical uncertainties, minor revisions and corrections, version to be published in Physical Review

PGB: A PubMed Graph Benchmark for Heterogeneous Network Representation Learning

There has been a rapid growth in biomedical literature, yet capturing the heterogeneity of the bibliographic information of these articles remains relatively understudied. Although graph mining research via heterogeneous graph neural networks has taken center stage, it remains unclear whether these approaches capture the heterogeneity of the PubMed database, a vast digital repository containing over 33 million articles. We introduce PubMed Graph Benchmark (PGB), a new benchmark dataset for evaluating heterogeneous graph embeddings for biomedical literature. PGB is one of the largest heterogeneous networks to date and consists of 30 million English articles. The benchmark contains rich metadata including abstract, authors, citations, MeSH terms, MeSH hierarchy, and some other information. The benchmark contains three different evaluation tasks encompassing systematic reviews, node classification, and node clustering. In PGB, we aggregate the metadata associated with the biomedical articles from PubMed into a unified source and make the benchmark publicly available for any future works

Transient x-ray absorption spectroscopy of hydrated halogen atom

Time-resolved x-ray absorption spectroscopy monitors the transient species generated by one-photon detachment of an electron from aqueous bromide. Hydrated bromine atoms with a lifetime of ca. 17 ns were observed, nearly half of which react with excess Br- to form Br2-. The K-edge spectra of the Br atom and Br2- anion exhibit distinctive resonant transitions that are absent for the Br- precursor. The absorption spectra indicate that the solvent shell around a Br0 atom is defined primarily by hydrophobic interactions, in agreement with a Monte Carlo simulation of the solvent structure.Comment: 6 pages, 4 figures + supplement, will be submitted to PR

Predictive control for soaring of unpowered autonomous UAVs

In this paper we propose an energy-harvesting controller design for a 3 degree-of-freedom glider in a nonlinear MPC framework. The glider is simulated within a generic atmospheric updraft environment with the aim of extracting the maximum amount of energy from the environment. We focus on conceptual feasibility at this stage and we take the realistic assumption that the glider is able to obtain updraft information only along the flight trajectory. The surrounding updraft distribution is then recursively estimated (online) by combining the measurements from the optimal trajectory with a heuristic search, if necessary. A variation of the standard grid search is used such that the grid spacing is altered depending on the updraft information along the glider’s flight path. Results from both standard and adaptive grid search approaches are presented. In abstract terms, this work can be viewed as finding optimal paths in uncertain vector fields

Translation to Inter-organizational Systems Integration: The Effect of Power and the Mediating Role of the Obligatory Passage Point

IOS integration has become a competitive necessity in recent industrial environment. Thus, in the supply chain, dominant firms often try to exert their power to influence their dependent firms to implement IOS integration. However, whether power helps or hurts an integrated IOS implementation is still an unresolved issue. Mixed results on this issue from prior studies demand a further examination on such a context. Based on the circuits of power framework and the concept of obligatory passage point (OPP), this study identifies three factors that mediate the effect of power on the implementation of IOS integration, including competitive necessity, interestingness, and firm readiness. We accordingly develop a theoretical model with six hypotheses. Based on a sample of 134 manufacturing firms and PLS analysis, all hypotheses receive empirical support from the data. The findings suggest that the flows of exercised power and potential power into IOS integration can go through those mediators. Exercised power can promote competitive necessity that lead dependent firms to perceive greater interestingness and achieve higher firm readiness, resulting in a high level of IOS integration. Potential power supplements exercised power in facilitating interestingness and firm readiness. These two types of power also demonstrate different effects on those mediators. While exercised power has a greater impact on competitive necessity and no impact on interestingness, potential power produces an opposite result. This study therefore clarifies the effect of different types of power on IOS implementation. Theoretical and practical implications of the results are provided. Available at: https://aisel.aisnet.org/pajais/vol8/iss3/4

Collective excitation of quantum wires and effect of spin-orbit coupling in the presence of a magnetic field along the wire

The band structure of a quantum wire with the Rashba spin-orbit coupling develops a pseudogap in the presence of a magnetic field along the wire. In such a system spin mixing at the Fermi wavevectors $-k_F$ and $k_F$ can be different. We have investigated theoretically the collective mode of this system, and found that the velocity of this collective excitation depends sensitively on the strength of the Rashba spin-orbit interaction and magnetic field. Our result suggests that the strength of the spin-orbit interaction can be determined from the measurement of the velocity.Comment: RevTeX 4 file, 4pages, 6 eps figures. To appear in Physical Review