515 research outputs found
Branching ratio and violation of decays in a modified perturbative QCD approach
We calculate the branching ratio and violations for decays
in a modified perturbative QCD approach based on factorization. The
resummation effect of the transverse momentum regulates the endpoint
singularity. Using the meson wave function that is obtained in the
relativistic potential model, soft contribution cannot be suppressed
effectively by Sudakov factor. Soft scale cutoff and soft , and
form factors have to be introduced. The most important
next-to-leading-order contributions from the vertex corrections, the quark
loops, and the magnetic penguins are also considered. In addition, the
contribution of the color-octet hadronic matrix element is included which is
essentially of long-distance dynamics. Our predictions for branching ratios and
violations are in good agreement with the experimental data. Especially
the theoretical result of dramatic difference between the violations of
and is consistent with experimental
measurement, therefore the puzzle in decays can be resolved in our
way of the modified perturbative QCD approach.Comment: 19 pages, 2 figures, version to appear in Phys. Rev.
Joint Deployment and Task Scheduling Optimization for Large-Scale Mobile Users in Multi-UAV Enabled Mobile Edge Computing
This article establishes a new multiunmanned aerial vehicle (multi-UAV)-enabled mobile edge computing (MEC) system, where a number of unmanned aerial vehicles (UAVs) are deployed as flying edge clouds for large-scale mobile users. In this system, we need to optimize the deployment of UAVs, by considering their number and locations. At the same time, to provide good services for all mobile users, it is necessary to optimize task scheduling. Specifically, for each mobile user, we need to determine whether its task is executed locally or on a UAV (i.e., offloading decision), and how many resources should be allocated (i.e., resource allocation). This article presents a two-layer optimization method for jointly optimizing the deployment of UAVs and task scheduling, with the aim of minimizing system energy consumption. By analyzing this system, we obtain the following property: the number of UAVs should be as small as possible under the condition that all tasks can be completed. Based on this property, in the upper layer, we propose a differential evolution algorithm with an elimination operator to optimize the deployment of UAVs, in which each individual represents a UAV's location and the entire population represents an entire deployment of UAVs. During the evolution, we first determine the maximum number of UAVs. Subsequently, the elimination operator gradually reduces the number of UAVs until at least one task cannot be executed under delay constraints. This process achieves an adaptive adjustment of the number of UAVs. In the lower layer, based on the given deployment of UAVs, we transform the task scheduling into a 0-1 integer programming problem. Due to the large-scale characteristic of this 0-1 integer programming problem, we propose an efficient greedy algorithm to obtain the near-optimal solution with much less time. The effectiveness of the proposed two-layer optimization method and the established multi-UAV-enabled MEC system is demonstrated on ten instances with up to 1000 mobile users
Anomalous pressure behavior of tangential modes in single-wall carbon nanotubes
Using the molecular dynamics simulations and the force constant model we have
studied the Raman-active tangential modes (TMs) of a (10, 0) single-wall carbon
nanotube (SWNT) under hydrostatic pressure. With increasing pressure, the
atomic motions in the three TMs present obvious diversities. The pressure
derivative of E1g, A1g, and E2g mode frequency shows an increased value (), a
constant value (), and a negative value () above 5.3 GPa, respectively. The
intrinsic characteristics of TMs consumedly help to understand the essence of
the experimental T band of CNT. The anomalous pressure behavior of the TMs
frequencies may be originated from the tube symmetry alteration from D10h to
D2h then to C2h.Comment: 15 pages, 3 pages, submitted to Phys. Rev.
3-(1,3-Benzodioxol-5-yl)-1-phenyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazine
In the title compound, C25H19NO3, the oxazine ring displays a half-chair conformation. The fused benzene ring is nearly parallel to the naphthyl ring system, the dihedral angle between this benzene ring and the naphthyl system being 8.52 (11)°. The imino group is not involved in hydrogen bonding in the crystal structure
A new AgI complex based on 1-[(1H-benzimidazol-1-yl)methyl]-1H-1,2,4-triazole
In the title complex, bis{μ-1-[(1H-benzimidazol-1-yl)methyl]-1H-1,2,4-triazole}disilver(I) dinitrate, [Ag2(C10H9N5)2](NO3)2, the AgI ion is nearly linearly coordinated [N—Ag—N angle is 155.72 (14)°] by two 1-[(1H-benzimidazole-1-yl)methyl]-1H-1,2,4-triazole (bmt) ligands. In addition, two bmt ligands link two AgI ions, forming a dinuclear unit with an Ag⋯Ag distance of 5.0179 (15) Å. The whole complex is generated by an inversion centre. The dinuclear units and the NO3
− counter-ions are connected by N—H⋯O hydrogen bonds and weak Ag⋯O interactions [2.831 (5), 2.887 (5) and 2.908 (5) Å], leading to a three-dimensional structure
Tetraaqua{1-[(1H-1,2,3-benzotriazol-1-yl)methyl]-1H-1,2,4-triazole}sulfatozinc(II) dihydrate
In the title complex, [Zn(SO4)(C9H8N6)(H2O)4]·2H2O, the ZnII ion is six-coordinated by one N atom from a 1-[(1H-1,2,3-benzotriazol-1-yl)methyl]-1H-1,2,4-triazole ligand and five O atoms from one monodentate sulfate anion and four water molecules in a distorted octahedral geometry. The sulfate tetrahedron is rotationally disordered over two positions in a 0.618 (19):0.382 (19) ratio. In the crystal, adjacent molecules are linked through O—H⋯O and O—H⋯N hydrogen bonds involving the cation, the anion, and the coordinated and uncoordinated water molecules into a three-dimensional network
Protective efficacy of a broadly cross-reactive swine influenza DNA vaccine encoding M2e, cytotoxic T lymphocyte epitope and consensus H3 hemagglutinin
BACKGROUND: Pigs have been implicated as mixing reservoir for the generation of new pandemic influenza strains, control of swine influenza has both veterinary and public health significance. Unlike human influenza vaccines, strains used for commercially available swine influenza vaccines are not regularly replaced, making the vaccines provide limited protection against antigenically diverse viruses. It is therefore necessary to develop broadly protective swine influenza vaccines that are efficacious to both homologous and heterologous virus infections. In this study, two forms of DNA vaccines were constructed, one was made by fusing M2e to consensus H3HA (MHa), which represents the majority of the HA sequences of H3N2 swine influenza viruses. Another was made by fusing M2e and a conserved CTL epitope (NP147-155) to consensus H3HA (MNHa). Their protective efficacies against homologous and heterologous challenges were tested. RESULTS: BALB/c mice were immunized twice by particle-mediated epidermal delivery (gene gun) with the two DNA vaccines. It was shown that the two vaccines elicited substantial antibody responses, and MNHa induced more significant T cell-mediated immune response than MHa did. Then two H3N2 strains representative of different evolutional and antigenic clusters were used to challenge the vaccine-immunized mice (homosubtypic challenge). Results indicated that both of the DNA vaccines prevented homosubtypic virus infections completely. The vaccines’ heterologous protective efficacies were further tested by challenging with a H1N1 swine influenza virus and a reassortant 2009 pandemic strain. It was found that MNHa reduced the lung viral titers significantly in both challenge groups, histopathological observation showed obvious reduction of lung pathogenesis as compared to MHa and control groups. CONCLUSIONS: The combined utility of the consensus HA and the conserved M2e and CTL epitope can confer complete and partial protection against homologous and heterologous challenges, respectively, in mouse model. This may provide a basis for the development of universal swine influenza vaccines
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