Remote preparation of optical cat states based on Gaussian entanglement

Remote state preparation enables one to prepare and manipulate quantum state non-locally. As an essential quantum resource, optical cat state is usually prepared locally by subtracting photons from a squeezed vacuum state. For remote quantum information processing, it is essential to prepare and manipulate optical cat states remotely based on Gaussian entanglement, which remains a challenge. Here, we present experimental preparation of optical cat states based on a remotely distributed two-mode Gaussian entangled state in a lossy channel. By performing photon subtraction and homodyne projective measurement at Alice's station, an optical cat state is prepared remotely at Bob's station. Furthermore, the prepared cat state is rotated by changing Alice's measurement basis of homodyne detection, which demonstrates the remote manipulation of it. By distributing two modes of the two-mode Gaussian entangled state in lossy channels, we demonstrate that the remotely prepared cat state can tolerate much more loss in Alice's channel than that in Bob's channel. We also show that cat states with amplitudes larger than 2 can be prepared by increasing the squeezing level and subtracting photon numbers. Our results make a crucial step toward remote hybrid quantum information processing involving discrete- and continuous-variable techniques

Diverse genetic mechanisms underlie worldwide convergent rice feralization

Background: Worldwide feralization of crop species into agricultural weeds threatens global food security. Weedy rice is a feral form of rice that infests paddies worldwide and aggressively outcompetes cultivated varieties. Despite increasing attention in recent years, a comprehensive understanding of the origins of weedy crop relatives and how a universal feralization process acts at the genomic and molecular level to allow the rapid adaptation to weediness are still yet to be explored. Results: We use whole-genome sequencing to examine the origin and adaptation of 524 global weedy rice samples representing all major regions of rice cultivation. Weed populations have evolved multiple times from cultivated rice, and a strikingly high proportion of contemporary Asian weed strains can be traced to a few Green Revolution cultivars that were widely grown in the late twentieth century. Latin American weedy rice stands out in having originated through extensive hybridization. Selection scans indicate that most genomic regions underlying weedy adaptations do not overlap with domestication targets of selection, suggesting that feralization occurs largely through changes at loci unrelated to domestication. Conclusions: This is the first investigation to provide detailed genomic characterizations of weedy rice on a global scale, and the results reveal diverse genetic mechanisms underlying worldwide convergent rice feralization

Putative DHHC-Cysteine-Rich Domain S-Acyltransferase in Plants

Protein S-acyltransferases (PATs) containing Asp-His-His-Cys within a Cys-rich domain (DHHC-CRD) are polytopic transmembrane proteins that are found in eukaryotic cells and mediate the S-acylation of target proteins. S-acylation is an important secondary and reversible modification that regulates the membrane association, trafficking and function of target proteins. However, little is known about the characteristics of PATs in plants. Here, we identified 804 PATs from 31 species with complete genomes. The analysis of the phylogenetic relationships suggested that all of the PATs fell into 8 groups. In addition, we analysed the phylogeny, genomic organization, chromosome localisation and expression pattern of PATs in Arabidopsis, Oryza sative, Zea mays and Glycine max. The microarray data revealed that PATs genes were expressed in different tissues and during different life stages. The preferential expression of the ZmPATs in specific tissues and the response of Zea mays to treatments with phytohormones and abiotic stress demonstrated that the PATs play roles in plant growth and development as well as in stress responses. Our data provide a useful reference for the identification and functional analysis of the members of this protein family

Technical performance analysis and economic evaluation of a compressed air energy storage system integrated with an organic Rankine cycle

© 2017 Elsevier Ltd Energy storage becomes increasingly important in balancing electricity supply and demand due to the rise of intermittent power generation from renewable sources. The compressed air energy storage (CAES) system as one of the large scale ( > 100 MW) energy storage technologies has been commercially deployed in Germany and the USA. However, the efficiency of current commercial CAES plants still needs to be improved. In this study, an integrated system consisting of a CAES system and an organic Rankine cycle (ORC) was proposed to recover the waste heat from intercoolers and aftercooler in the charging process and exhaust stream of the recuperator in discharging process of the CAES system. Steady state process models of the CAES system and ORC were developed in Aspen Plus®. These models were validated using data from the literature and the results appear in a good agreement. Process analysis was carried out using the validated models regarding the impact of different organic working fluids (R123, R134a, R152a, R245fa, R600a) of ORC and expander inlet pressures of the ORC on system performance. It was found that integrating ORC with the CAES system as well as selecting appropriate working fluid was a reasonable approach for improving performance of the CAES system. The round-trip efficiency was improved by 3.32–3.95% using five working fluids, compared to that of the CAES system without ORC. Economic evaluation on levelized cost of electricity (LCOE) was performed using Aspen Process Economic Analyser® (APEA). Different working fluids in ORC and different power sources (e.g. wind and solar) associated with the integrated system were considered to estimate the LCOEs. It was found that the LCOEs for the integrated system were competitive with fossil-fuel fired power and even lower than offshore wind power and solar power. The proposed research presented in this paper hopes to shed light on how to improve efficiency and reduce cost when implementing CAES

Effect of Multi-Sized Dust Distribution on Local Plasma Sheath Potentials

This work investigates the modification of a plasma sheath in a complex plasma due to the presence of dust particles with a specified size distribution. A self-consistent model for the plasma sheath is combined with a self-consistent dynamical code in order to determine the interaction of the dust particles with the local sheath potential and the subsequent effect on the dynamics of the particles. It is shown that the ion density in the region of levitated particles is decreased. The sheath potential in the region of levitated dust particles is also more negative which is qualitatively consistent with the experimental results of Arnas et al. [Arnas, C., Mikikian, M., Bachet, G., Doveil, F. Sheath modification in the presence of dust particles. Phys. Plasmas 7(11), 4418–4422, 2000.].Dusty plasma sheathMulti-sized dust distribution;Plasma crystalcomplex plasm

Molecular Cloning and Expression Analysis of a Hexokinase Gene, MdHXK1 in Apple

A hexokinase gene named MdHXK1 (MDP0000309677) was cloned from ‘Gala’ apple (Malus × domestica Borkh.). Sequence analysis showed that the MdHXK1 gene was 1 497 bp long and encoded 499 amino acids. The predicted molecular mass of this protein was 54.05 kD, and the pI was 5.76. A phylogenetic tree indicated apple MdHXK1 exhibited the highest sequence similarity to Pyrus bretschneideri PbHXK1. Analysis of the functional domain showed that the MdHXK1 protein included two conserved kinase domains. The prediction of subcellular localization suggested that the MdHXK1 protein was mainly localized in the cytoplasm. There was an indication that MdHXK1 existed as one copy in the apple genome by Southern blotting. Silico analysis suggested that the promoter sequence contained several typical cis-acting elements, including defense, sugar signaling and phytohormone responsive elements. Quantitative real-time PCR analysis demonstrated that the MdHXK1 gene was mainly expressed in stem and flower tissues. During the development of apple fruits, the expression of the MdHXK1 gene initially increased and then decreased. The changes on Glc phosphorylation relative activity and glucose concentration showed the same trend. In addition, the expression of this gene was induced by salt stress, low temperature, and abscisic acid (ABA). Finally, we obtained and purified the fused MdHXK1 protein by recombinant prokaryotic expression. Studies have demonstrated that MdHXK1 may participate in sugar metabolism in apple fruits. Enzyme encoded by MdHXK1 is a key factor in the mediation of sugar accumulation. Recently, researchers on hexokinase at home and abroad mainly focused on model plants, such as Arabidopsis, tobacco and rice, but orchard fruit like apple were underresearched. Our research established the foundation for the further study of the functions of MdHXK1

Research on operating parameters of T-groove cylindrical gas film seal based on computational fluid dynamics

Cylindrical gas film sealing technology is a new type of dry gas sealing technology. Compared with the face gas film sealing technology, the cylindrical gas film seal presents a strong floating property, which can reduce the vibration and thermal deformation of the rotor system. In this article, the effect of operating parameters such as speed, pressure difference and viscosity on the T-groove gas cylindrical film seal performance are studied in detail by the method of control variable in computational fluid dynamics software, and pressure distribution, gas film stiffness, leakage, leakage stiffness ratio and hydrodynamic force are analysed. Results show that with the increase of the rotational speed, static pressure, hydrodynamic force and film stiffness increase, but leakage decreases first and then increases. Furthermore, the results indicate that with the increase of pressure difference, the static pressure, leakage and hydrodynamic force increase. In addition, the simulations show that when the viscosity increases, the maximum pressure and film stiffness increase, but the leakage decreases. This indicates that as the rotational speed increases, the hydrodynamic effect and the amount of gas overflow in the axial direction increase, resulting in an increase of leakage. Lastly, the results also show that when the pressure difference increases, both the radial and axial gas flow rates increase, resulting in an increase in both the film stiffness and the leakage. With the increase of viscosity, the viscous shear force and fluid hydrodynamic force increase, resulting in the increase of the gas film stiffness. This study can provide a theoretical basis in industrial applications for setting the operating parameters and serving as a reference

Effect of T-groove Parameters on Steady-State Characteristics of Cylindrical Gas Seal

Gas film seal technology is becoming increasingly important as an advanced new rotary shaft seal technology in aviation engines and industrial gas turbines. In this paper the impacts of several parameters of T-groove cylindrical gas seal such as groove number, groove depth, groove width ratio, dam groove width ratio and floating ring length on the steady-state characteristics of cylinder film seal are studied in detail by the method of control variable using computational fluid dynamics software, and the focuses are on the pressure distribution, the gas film stiffness, and the leakage. Results show that with the increase of the number of grooves, the gas film stiffness increases gradually, but the leakage and leakage stiffness ratio decrease. The results also show that with the increase of groove depth, there is a maximum value for the gas film stiffness and a minimum value forleakage. This research plays an important role in guiding the design and the application of cylindrical gas seal

Analysis of Wear Performance of Two Finger Seal Structure

To reveal the wear law of parabola-shaped and arc-shaped finger seals (FSs), the wear characteristics of parabola-shaped and arc-shaped FSs were studied in this paper. Firstly, a formula for calculating the contact stress of finger boot/rotor is established according to bootlace theory. Secondly, based on the mathematical model of wear rate in related literature, the influence of structural parameters on FS wear was investigated. Results showed that when the rotor speed is less than 1700 r/min, the contact stress of the parabolic FS is less than that of the arc-shaped FS; when the rotation speed is greater than 1700 r/min, the contact stresses of the parabolic and arc-shaped FSs increase rapidly. Furthermore, when the speed is greater than 4000 r/min, the contact stresses of the two structures are similar. When the rotor speed is less than 3000 r/min, the trends of the wear rate of the parabolic and arc-shaped FS structures are irregular; when the rotor speed is greater than 3000 r/min, the wear rate of the parabolic FS structure is greater than the arc-shaped FS, and the wear rates of the two structures increase exponentially. Our results provide theoretical basis and reference for the wear performance of PFS and AFS