Semimetalic graphene in a modulated electric potential

The $\pi$-electronic structure of graphene in the presence of a modulated electric potential is investigated by the tight-binding model. The low-energy electronic properties are strongly affected by the period and field strength. Such a field could modify the energy dispersions, destroy state degeneracy, and induce band-edge states. It should be noted that a modulated electric potential could make semiconducting graphene semimetallic, and that the onset period of such a transition relies on the field strength. There exist infinite Fermi-momentum states in sharply contrast with two crossing points (Dirac points) for graphene without external fields. The finite density of states (DOS) at the Fermi level means that there are free carriers, and, at the same time, the low DOS spectrum exhibits many prominent peaks, mainly owing to the band-edge states.Comment: 12pages, 5 figure

A simplified approach to the multi-item economic production quantity model with scrap, rework, and multi-delivery

AbstractIn a recent paper, Chiu et al. (2014) utilized mathematical modeling and differential calculus to determine the common production cycle time that minimizes total production, inventory, and delivery costs for a multi-item economic production quantity (EPQ) model with scrap, rework, and multi-delivery. The present study proposes an algebraic approach substituting the use of differential calculus on the system cost function for deriving the optimal common cycle time in the aforementioned multi-item EPQ model. This simplified approach may enable managing practitioners to resolve real multi-item EPQ models more effectively

Long-distance anticipatory vowel-to-vowel assimilatory effects in French and Japanese

This paper examines language-specific differences in anticipatory vowel-to-vowel coarticulation using two non-stress languages. Native speakers of Standard French (n=6) and Tokyo Japanese (n=5) served as subjects to a production study. To investigate possible long-distance effects between and beyond adjacent vowels, linguistic material consisting of /ba.bV/ and /ba.ba.bV/ was embedded within a carrier sentence in each language. The word-final trigger vowel (V) is /a/, /i/ or /u/. Acoustic analysis of continuous F1 and F2 trajectories as well as singlepoint formant measurements revealed opposite patterns in the two languages. Strong anticipatory effects in vowels up to 2 preceding syllables were observed in French. However, Japanese displayed few statistically significant anticipatory effects in any vowel preceding any trigger. We interpret the results as an indication that there are two rather different types of contextual phonetic variability. We also assert not all phonetic assimilatory effects in “coarticulation” are due to articulatory overlap.postprin

Large collective Lamb shift of two distant superconducting artificial atoms

Virtual photons can mediate interaction between atoms, resulting in an energy shift known as a collective Lamb shift. Observing the collective Lamb shift is challenging, since it can be obscured by radiative decay and direct atom-atom interactions. Here, we place two superconducting qubits in a transmission line terminated by a mirror, which suppresses decay. We measure a collective Lamb shift reaching 0.8% of the qubit transition frequency and exceeding the transition linewidth. We also show that the qubits can interact via the transmission line even if one of them does not decay into it.Comment: 7+5 pages, 4+2 figure