To describe accurately the electronic structures of carbon nanotubes, a semi-empirical tight-binding approach is presented in which the main intrinsic curvatures have been fully taken into account. The calculated electronic structures and band gaps are consistent with experimental measurements. Studies of the relative importance of various intrinsic curvatures show that each curvature has a contribution of varying importance to the curvature-induced band gap. Additionally, under both uniaxial and torsional strain, semiconductor–metal–semiconductor phase transitions have been observed for primary metallic carbon nanotubes. The critical stress of the transition and the gap’s sensitivity with stress are dependent on both the diameter and chirality of nanotubes, which is at variance with previous predictions.

Automated program repair (APR) aims to find an automatic solution to program language bugs without human intervention, and it can potentially reduce debugging costs and improve software quality.Conventional approaches adopt learning-based methods such as sequence-to-sequence models for the patches generation. However, they tend to ignore the code structure information and suffer from grammar and syntax errors. To consider the grammar and syntax information, in this paper, we propose a grammar-based ruleto-rule model, which regards the repair process as the transformation of grammar rules, and leverages two encoders modeling both the original token sequence and the grammar rules, enhanced with a new tree-based self-attention. Besides, to guarantee grammar correctness, we employ a grammatically restricted inference method to generate each grammar rule in a legally constrained sub-search-space considering the generated previous rules. Experimental evaluations on a Java dataset demonstrate that the proposed approach significantly outperforms the state-of-the-art baselines in terms of generated code accuracy.

No abstract

No abstract

No abstract

A theoretical investigation of a dual-channel optical fibre surface plasmon resonance (SPR) hydrogen sensor based on wavelength modulation is presented in this paper. The matrix method for the multilayer model is used to calculate the normalized output power. The effect of the thickness of each layer of two four-layer stacks on the characteristics of the output spectrum of the proposed sensor is discussed. The suitable thickness of each layer is used for the configuration of the proposed sensor. Simulation results demonstrate that two resonant wavelengths from two channels independently depend on the hydrogen concentrations in the respective channels, and there is a one-to-one relationship between the resonant wavelength and hydrogen concentration for each channel. The proposed sensor can achieve the simultaneous detection of hydrogen concentrations in two different areas by measuring the resonant wavelength of each channel.

Seed rain patterns are a crucial influence on plant regeneration. Although it is very challenging to understand the dynamics of seed rain, long-term monitoring of seeds can provide useful insights. In this study, we monitored seed rain patterns of forests dominated by Parashorea chinensis in Xishuangbanna, Southwest China for nine years. We recorded 8,993,224 seeds belonging to 226 species, between May 2008 and April 2017. We categorized seeds of 77 species as large, 61 species as medium, 72 species as small, 13 species as tiny, 1 species as infinitesimally grainy seed and 2 species as filamentous. More than 70% of all seeds belong to the top 10 dominant species. Seeds of all types showed pronounced inter-annual variation for both seed number and species number. At least one mast seeding was observed for each of the seed type during nine years.

We examined the effect of intravascular volume expansion (VE) on the arterial baroreflex control of pulse rate (PR) in conscious, chronically instrumented monkeys tethered in their cages. A total of five monkeys was studied after surgical implantation of catheters in the descending aorta, the left atrium, and the internal jugular vein. Mean arterial blood pressure (MABP)-PR stimulus response curves were constructed by decreasing and increasing blood pressure with nitroprusside and phenylephrine, respectively. The data were analyzed with a regression analysis that generated a sigmoid curve and the maximum sensitivity (slope) of the curve. The data were obtained before and after VE with an isotonic isoncotic dextran solution equal to 20% of the estimated blood volume. After VE, the MABP-PR curve shifted to the right at the high blood pressures, and there was a significant decrease in the maximum sensitivity from 5.65 +/- 1.44 for control to 2.14 +/- 0.63 after VE (P less than 0.05). We concluded that VE attenuates the baroreflex control of heart rate in the conscious nonhuman primate.