Giant and tunable valley degeneracy splitting in MoTe2

Monolayer transition-metal dichalcogenides possess a pair of degenerate helical valleys in the band structure that exhibit fascinating optical valley polarization. Optical valley polarization, however, is limited by carrier lifetimes of these materials. Lifting the valley degeneracy is therefore an attractive route for achieving valley polarization. It is very challenging to achieve appreciable valley degeneracy splitting with applied magnetic field. We propose a strategy to create giant splitting of the valley degeneracy by proximity-induced Zeeman effect. As a demonstration, our first principles calculations of monolayer MoTe$_2$ on a EuO substrate show that valley splitting over 300 meV can be generated. The proximity coupling also makes interband transition energies valley dependent, enabling valley selection by optical frequency tuning in addition to circular polarization. The valley splitting in the heterostructure is also continuously tunable by rotating substrate magnetization. The giant and tunable valley splitting adds a readily accessible dimension to the valley-spin physics with rich and interesting experimental consequences, and offers a practical avenue for exploring device paradigms based on the intrinsic degrees of freedom of electrons.Comment: 8 pages, 5 figures, 1 tabl

Chaos-assisted two-octave-spanning microcombs

Since its invention, optical frequency comb has revolutionized a broad range of subjects from metrology to spectroscopy. The recent development of microresonator-based frequency combs (microcombs) provides a unique pathway to create frequency comb systems on a chip. Indeed, microcomb-based spectroscopy, ranging, optical synthesizer, telecommunications and astronomical calibrations have been reported recently. Critical to many of the integrated comb systems is the broad coverage of comb spectra. Here, microcombs of more than two-octave span (450 nm to 2,008 nm) is demonstrated through χ^((2)) and χ^((3)) nonlinearities in a deformed silica microcavity. The deformation lifts the circular symmetry and creates chaotic tunneling channels that enable broadband collection of intracavity emission with a single waveguide. Our demonstration introduces a new degree of freedom, cavity deformation, to the microcomb studies, and our microcomb spectral range is useful for applications in optical clock, astronomical calibration and biological imaging

Geometric and Electronic Structure of Graphene Bilayer Edges

We present a computational investigation of free-standing graphene bilayer edge (BLE) structures, aka “fractional nanotubes.” We demonstrate that these curved carbon nanostructures possess a number of interesting properties, electronic in origin. The BLEs, quite atypical of elemental carbon, have large permanent electric dipoles of 0.87 and 1.14 debye/Å for zigzag and armchair inclinations, respectively. An unusual, weak AA interlayer coupling leads to a twinned double-cone dispersion of the electronic states near the Dirac points. This entails a type of quantum Hall behavior markedly different from what has been observed in graphenebased materials, characterized by a magnetic field-dependent resonance in the Hall conductivity

Clinical Significance of Preoperative Neutrophil Lymphocyte Ratio versus Platelet Lymphocyte Ratio in Patients with Small Cell Carcinoma of the Esophagus

Recent studies have shown that the presence of systemic inflammation correlates with poor survival in various of cancers. The aim of this study was to determine the prognostic values of neutrophil lymphocyte ratio (NLR) and platelet lymphocyte ratio (PLR) in patients with small cell carcinoma of the esophagus (SCCE). Preoperative NLR and PLR were evaluated in 43 patients with SCCE from January 2001 to December 2010. The prognostic significance of both markers was then determined by both uni- and multivariate analytical methods. Receiver operating characteristic (ROC) curves were also plotted to verify the accuracy of NLR and PLR for survival prediction. Patients with PLR ≥150 had significantly poorer (relapse-free survival) RFS and (overall survival) OS compared to patients with PLR <150. However, RFS or OS did not differ according to NLR categories (<3.5 and ≥3.5). The areas under the curve (AUC) indicated that PLR was superior to NLR as a predictive factor. The results of the present study conclude that PLR is superior to NLR as a predictive factor in patients with SCCE

Some inequalities of Hermite-Hadamard type for GA-Convex functions with applications to means

In the paper, the authors, by Hölder's inequality, establish some Hermite-Hadamard type integral inequalities for GA-convex functions and apply these inequalities to construct several inequalities for special means