Universal Quantum Degeneracy Point for Superconducting Qubits

The quantum degeneracy point approach [D. Vion et al., Science 296, 886 (2002)] effectively protects superconducting qubits from low-frequency noise that couples with the qubits as transverse noise. However, low-frequency noise in superconducting qubits can originate from various mechanisms and can couple with the qubits either as transverse or as longitudinal noise. Here, we present a quantum circuit containing a universal quantum degeneracy point that protects an encoded qubit from arbitrary low-frequency noise. We further show that universal quantum logic gates can be performed on the encoded qubit with high gate fidelity. The proposed scheme is robust against small parameter spreads due to fabrication errors in the superconducting qubits.Comment: 7 pages, 4 figure

Interest rate regulation, earnings transparency and capital structure: evidence from Chinese listed companies, 2003-2015

We use samples from Chinese listed companies to investigate the effects of interest rate deregulation and earnings transparency on company’s capital structure in China over the period of 2003-2015. In particular, we study the link between state-owned enterprises (SOEs), economic growth targets, and marketization in China's unique institutional context. The results show earnings transparency increases firm leverage and the additional tests suggest that such an effect takes place via a mechanism by reducing the cost of debt finance. However, information transparency could moderate the effects of interest rate deregulation on corporate capital structure. In addition, it finds that SOEs are less sensitive towards the changes of interest rates in China because lending to SOEs is policy-oriented and lacks of market evaluation of business risk. Government control is conducive to enhancing the transparency of the whole industry, however, market-oriented reform is conducive to enhancing the transparency of the company's own information. The results are robust to endogeneity tests and a variety of variable and model specifications. Lastly, we find that information transparency has little impact on equity financing because of IPO and SEO strictly controlled by the Chinese government. These findings are important for management and policy implications. The paper makes contribution to the relationship between earnings disclosure quality and capital structure in the Chinese unique institutional context, such as taking the progressive interest rate reform, SOES, different economic growth target and different marketization level in each province of China. We suggest that investors will pay more attention to the company's own unique information transparency in the provinces with high degree of marketization. As a potential direction for future research, we will investigate how the earnings transparency has impact on capital structure, and how such impact would depend on the transparency of specific business, the cap of foreign shareholding and the convenience of investment

Experimental study on transcritical Rankine cycle (TRC) using CO2/R134a mixtures with various composition ratios for waste heat recovery from diesel engines

A carbon dioxide (CO2) based mixture was investigated as a promising solution to improve system performance and expand the condensation temperature range of a CO2 transcritical Rankine cycle (C-TRC). An experimental study of TRC using CO2/R134a mixtures was performed to recover waste heat of engine coolant and exhaust gas from a heavy-duty diesel engine. The main purpose of this study was to investigate experimentally the effect of the composition ratio of CO2/R134a mixtures on system performance. Four CO2/R134a mixtures with mass composition ratios of 0.85/0.15, 0.7/0.3, 0.6/0.4 and 0.4/0.6 were selected. The high temperature working fluid was expanded through an expansion valve and then no power was produced. Thus, current research focused on the analysis of measured operating parameters and heat exchanger performance. Heat transfer coefficients of various heat exchangers using supercritical CO2/R134a mixtures were provided and discussed. These data may provide useful reference for cycle optimization and heat exchanger design in application of CO2 mixtures. Finally, the potential of power output was estimated numerically. Assuming an expander efficiency of 0.7, the maximum estimations of net power output using CO2/R134a (0.85/0.15), CO2/R134a (0.7/0.3), CO2/R134a (0.6/0.4) and CO2/R134a (0.4/0.6) are 5.07 kW, 5.45 kW, 5.30 kW, and 4.41 kW, respectively. Along with the increase of R134a composition, the estimation of net power output, thermal efficiency and exergy efficiency increased at first and then decreased. CO2/R134a (0.7/0.3) achieved the maximum net power output at a high expansion inlet pressure, while CO2/R134a (0.6/0.4) behaves better at low pressure

Integer quantum Hall effect and topological phase transitions in silicene

We numerically investigate the effects of disorder on the quantum Hall effect (QHE) and the quantum phase transitions in silicene based on a lattice model. It is shown that for a clean sample, silicene exhibits an unconventional QHE near the band center, with plateaus developing at $\nu=0,\pm2,\pm6,\ldots,$ and a conventional QHE near the band edges. In the presence of disorder, the Hall plateaus can be destroyed through the float-up of extended levels toward the band center, in which higher plateaus disappear first. However, the center $\nu=0$ Hall plateau is more sensitive to disorder and disappears at a relatively weak disorder strength. Moreover, the combination of an electric field and the intrinsic spin-orbit interaction (SOI) can lead to quantum phase transitions from a topological insulator to a band insulator at the charge neutrality point (CNP), accompanied by additional quantum Hall conductivity plateaus.Comment: 7 pages, 4 figure

Spatial imaging of Zn and other elements in Huanglongbing-affected grapefruit by synchrotron-based micro X-ray fluorescence investigation

Huanglongbing (HLB) is a highly destructive, fast-spreading disease of citrus, causing substantial economic losses to the citrus industry worldwide. Nutrient levels and their cellular distribution patterns in stems and leaves of grapefruit were analysed after graft-inoculation with lemon scions containing 'Candidatus Liberibacter asiaticus' (Las), the heat-tolerant Asian type of the HLB bacterium. After 12 months, affected plants showed typical HLB symptoms and significantly reduced Zn concentrations in leaves. Micro-XRF imaging of Zn and other nutrients showed that preferential localization of Zn to phloem tissues was observed in the stems and leaves collected from healthy grapefruit plants, but was absent from HLB-affected samples. Quantitative analysis by using standard references revealed that Zn concentration in the phloem of veins in healthy leaves was more than 10 times higher than that in HLB-affected leaves. No significant variation was observed in the distribution patterns of other elements such as Ca in stems and leaves of grapefruit plants with or without graft-inoculation of infected lemon scions. These results suggest that reduced phloem transport of Zn is an important factor contributing to HLB-induced Zn deficiency in grapefruit. Our report provides the first in situ, cellular level visualization of elemental variations within the tissues of HLB-affected citrus. © 2014 © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology

Exploiting novel properties of space-filling curves for data analysis

Using space-filling curves to order multidimensional data has been found to be useful in a variety of application domains. This paper examines the space-filling curve induced ordering of multidimensional data that has been transformed using shape preserving transformations. It is demonstrated that, although the orderings are not invariant under these transformations, the probability of an ordering is dependent on the geometrical configuration of the multidimensional data. This novel property extends the potential applicability of space-filling curves and is demonstrated by constructing novel features for shape matching

Cloning and heterologous expression of the plasmidencoded shsp gene of Streptococcus thermophilus isolated from Chinese dairy

We first tested 12 strains of Streptococcus thermophilus isolated from China yogurt or its starter culture for their plasmid content. Two strains were found to harbor two plasmids, identified as pQC1 and pQC2, from the S. thermophilus ST-QC, as well as pHS1 and pHS2 from the S. thermophilus ST-HS. Agarose gel electrophoresis profiles indicated that the molecular size of about 4.5 kb for the two bigger plasmids (pQC1 and pHS1) was nearly identical, same with the molecular size of approximately 3.5 kb for the two smaller plasmids (pQC2 and pHS2). A 765 bp DNA fragment, including a 429 bp open reading frame of the shsp gene of the smaller plasmid pQC2 from S. thermophilus St-QC, was successfully cloned and sequenced. Multiple sequence alignment revealed that the nucleotide sequence of the coding region of the shsp gene or the deduced amino acid sequence of the sHSP protein shared a high degree of identity (> 86.67 or 81.33% identity) with the shsp genes or the sHSP proteins described from other S. thermophilus plasmids. In addition, 222 bp nucleotide sequences upstream and 114 bp nucleotide sequences downstream belonging to the shsp gene coding region were also analyzed. The separation of SDS-PAGE and the analysis of Western blotting for the soluble cell proteins showed that the shsp gene of plasmid pQC2 of S. thermophilus St-QC was  successfully expressed in mesophilic Escherichia coli. In addition to strong heat and acid tolerance, recombinant E. coli cells overexpressing the S. thermophilus St-QC shsp gene had significantly higher resistance to ethanol stress, which is the first physiological function found to be linked to the S. thermophilus plasmid-borne shsp gene. This study will provide a basis for the cloning and expression of the shsp genes from a thermophilic microorganism in the mesophilic LAB or yeast and for further development of stress-resistant microorganism strains used in dairy fermentation and brewing wine.Key words: Streptococcus thermophilus, plasmid, small heat shock protein gene (shsp gene), cloning, expression, abiotic stresses, Escherichia coli

Local trace formulae and scaling asymptotics in Toeplitz quantization, II

In the spectral theory of positive elliptic operators, an important role is played by certain smoothing kernels, related to the Fourier transform of the trace of a wave operator, which may be heuristically interpreted as smoothed spectral projectors asymptotically drifting to the right of the spectrum. In the setting of Toeplitz quantization, we consider analogues of these, where the wave operator is replaced by the Hardy space compression of a linearized Hamiltonian flow, possibly composed with a family of zeroth order Toeplitz operators. We study the local asymptotics of these smoothing kernels, and specifically how they concentrate on the fixed loci of the linearized dynamics.Comment: Typos corrected. Slight expository change