D0 dimuon charge asymmetry from B_s system with Z' couplings and the recent LHCb result

The D0 collaboration has announced the observation of the like-sign dimuon charge asymmetry since 2010, which has more than 3\sigma deviation from the Standard Model prediction. One of the promising explanation is considering the existence of flavor changing Z' couplings to the b and s quarks which can contribute to the off-diagonal decay width in the B_s - \bar{B}_s mixing. Model construction is highly constrained by the recent LHCb data of 1fb^{-1} integrated luminosity . In this paper, we analyze the experimental constraints in constructing new physics models to explain the dimuon charge asymmetry from the CP violation of the B_s system. We present limits on Z' couplings and show that it is impossible to obtain the 1\sigma range of the dimuon charge asymmetry without the new contribution in the B_d system. Even with arbitrary contribution in the B_d system, the new couplings must be in the fine tuned region.Comment: 34 pages, 12 figures, Additional analyses and references are updated. (Conclusion unchanged.

Fast Marching based Rendezvous Path Planning for a Team of Heterogeneous Vehicle

A formulation is developed for deterministically calculating the optimized paths for a multi-agent system consisting of heterogeneous vehicles. The essence of this formulation is the calculation of the shortest time for each agent to reach every grid point from its known initial position. Such arrival time map can be readily assessed using the Fast Marching Method (FMM), a computational algorithm originally designed for solving boundary value problems of the Eikonal equation. Leveraging the FMM method, we demonstrate that the minimal time rendezvous point and paths for all member vehicles can be uniquely determined with minimal computational concerns. To showcase the potential of our method, we use an example of a virtual rendezvous scenario that entails the coordination of a ship, an underwater vehicle, an aerial vehicle, and a ground vehicle to converge at the optimal location within the Tampa Bay area in minimal time. It illustrates the value of the developed framework in efficiently constructing continuous path planning, while accommodating different operational constraints of heterogeneous member vehicles

Constant-Factor Approximation Algorithms for the Parity-Constrained Facility Location Problem

Facility location is a prominent optimization problem that has inspired a large quantity of both theoretical and practical studies in combinatorial optimization. Although the problem has been investigated under various settings reflecting typical structures within the optimization problems of practical interest, little is known on how the problem behaves in conjunction with parity constraints. This shortfall of understanding was rather discouraging when we consider the central role of parity in the field of combinatorics. In this paper, we present the first constant-factor approximation algorithm for the facility location problem with parity constraints. We are given as the input a metric on a set of facilities and clients, the opening cost of each facility, and the parity requirement - odd, even, or unconstrained - of every facility in this problem. The objective is to open a subset of facilities and assign every client to an open facility so as to minimize the sum of the total opening costs and the assignment distances, but subject to the condition that the number of clients assigned to each open facility must have the same parity as its requirement. Although the unconstrained facility location problem as a relaxation for this parity-constrained generalization has unbounded gap, we demonstrate that it yields a structured solution whose parity violation can be corrected at small cost. This correction is prescribed by a T-join on an auxiliary graph constructed by the algorithm. This auxiliary graph does not satisfy the triangle inequality, but we show that a carefully chosen set of shortcutting operations leads to a cheap and sparse T-join. Finally, we bound the correction cost by exhibiting a combinatorial multi-step construction of an upper bound

Micro-nano hybrid structures with manipulated wettability using a two-step silicon etching on a large area

Nanoscale surface manipulation technique to control the surface roughness and the wettability is a challenging field for performance enhancement in boiling heat transfer. In this study, micro-nano hybrid structures (MNHS) with hierarchical geometries that lead to maximizing of surface area, roughness, and wettability are developed for the boiling applications. MNHS structures consist of micropillars or microcavities along with nanowires having the length to diameter ratio of about 100:1. MNHS is fabricated by a two-step silicon etching process, which are dry etching for micropattern and electroless silicon wet etching for nanowire synthesis. The fabrication process is readily capable of producing MNHS covering a wafer-scale area. By controlling the removal of polymeric passivation layers deposited during silicon dry etching (Bosch process), we can control the geometries for the hierarchical structure with or without the thin hydrophobic barriers that affect surface wettability. MNHS without sidewalls exhibit superhydrophilic behavior with a contact angle under 10°, whereas those with sidewalls preserved by the passivation layer display more hydrophobic characteristics with a contact angle near 60°

Lack of Association between Polymorphisms of the Dopamine Receptor D4 and Dopamine Transporter Genes and Personality Traits in a Korean Population

Human personality traits have a considerable genetic component. Cloninger et al. were the first to postulate that certain personality traits, such as novelty seeking, are related to the dopamine neurotransmitter system. In this study, we investigated the associations between dopamine receptor D4 (DRD4) exon III and dopamine transporter (DAT1) polymorphisms and personality traits. The DRD4 and DAT1 gene polymorphisms were genotyped in 214 healthy Korean subjects, whose personality traits were assessed with the Temperament and Character Inventory (TCI). There were no significant differences between scores of TCI temperament dimensions (novelty seeking, harm avoidance, reward dependence, and persistence) and DRD4 gene polymorphism. The DAT1 gene polymorphisms also showed no significant association with any of the temperament subscales of the TCI. These data suggest that DRD4 and DAT1 gene polymorphism may not associated with personality traits in a Korean population

Electronic structure of single-walled carbon nanotubes on ultrathin insulating films

The electronic structures of single-walled carbon nanotubes on Ag(100) and on ultrathin insulating NaCl(100)/Ag(100) were studied using low-temperature scanning tunneling microscopy. The Fermi level of the nanotubes was shifted toward the conduction band on Ag(100), while it was shifted toward the valence band on NaCl films. We explain this opposite behavior by different basic mechanisms accounting for the Fermi level shifts. On the metal surface, the work function difference between the tube and the substrate determines the direction of the Fermi level shift. In the case of carbon nanotubes on insulating films, the electric field resulting from the dipole moment formed at the interface between the insulating film and the metal plays a decisive role in determining the Fermi level.open8

Controlling water dissociation on an ultrathin MgO film by tuning film thickness

Periodic density-functional theory calculations at the single-molecule level were used to study dissociation of water on ultrathin MgO films with varying thickness deposited on the Ag(100) surface. The enhanced chemical activity for water dissociation on MgO/Ag(100) originates from the greater stability of dissociated products, which is due in turn to the strong hybridization of their electronic states at the oxide-metal interface. Our results provide insights into the superiority of the monolayer MgO film surface over the bulk surface and the use of the film thickness to control heterogeneous catalysis in water dissociation.open11