Two Evolutionary Histories in the Genome of Rice: the Roles of Domestication Genes

Genealogical patterns in different genomic regions may be different due to the joint influence of gene flow and selection. The existence of two subspecies of cultivated rice provides a unique opportunity for analyzing these effects during domestication. We chose 66 accessions from the three rice taxa (about 22 each from Oryza sativa indica, O. sativa japonica, and O. rufipogon) for whole-genome sequencing. In the search for the signature of selection, we focus on low diversity regions (LDRs) shared by both cultivars. We found that the genealogical histories of these overlapping LDRs are distinct from the genomic background. While indica and japonica genomes generally appear to be of independent origin, many overlapping LDRs may have originated only once, as a result of selection and subsequent introgression. Interestingly, many such LDRs contain only one candidate gene of rice domestication, and several known domestication genes have indeed been “rediscovered” by this approach. In summary, we identified 13 additional candidate genes of domestication

Experimental Research on Indicator Diagrams of a Water Lubricated Screw Air Compressor

In recent years, water-lubricated screw compressors have attracted more and more attention, because this type of compressors can produce the high quality air completely free of oil and there is no contamination. However, poor sealing and lubricating properties of water might result in different operating characteristics compared with those of oil-injected compressors. A good understanding of the operating mechanisms is essential in any attempt to increase the performance of the compressor, which can be achieved by means of the indicator diagram. In this paper, a prototype of the water-lubricated screw air compressor was developed and a test rig was established. A series of pressure transducers were arranged in consecutive positions of the casing to measure the pressure distribution inside working chamber of the compressor. In addition, volumetric efficiency, adiabatic efficiency and mechanical efficiency of the compressor under different operating conditions were calculated based on measured volumeric flow-rate and power consumption. As a result, the influence mechanisms of rotating speed, discharge pressure and water injection flow-rate on the compressor performance and working process were analyzed based on indicator diagrams

Experimental investigation on an ORC twin-screw expander with an emphasis on its suction process

Organic Rankine Cycle (ORC) is an effective and promising technology to recover low-grade waste heat and output electricity. As a key component in an ORC system, the expander’s performance significantly affects the whole system’s efficiency. Twin-screw expander is widely employed for its compact structure, reliability, two-phase tolerance and high efficiency. To investigate the characteristics of twin-screw expander, a test bench was set up in a laboratory taking 120 waste steam as heat source. R245fa was selected as the working fluid. Pressure sensors with high sensitivity and accuracy were installed at appropriate locations in the expander casing to monitor the p-V indicator diagrams. The expander’s p-V indicator diagrams and operating parameters were recorded under different operating conditions. The effects of rotational speed and suction pressure on the expander’s suction pressure drop, volumetric efficiency and indicated adiabatic efficiency were studied. Results show that rotational speed and suction pressure affect the suction pressure drop altogether, which has a significant effect on the density and mass flow rate of the sucked gas. The expander volumetric efficiency is above 85% and the indicated adiabatic efficiency can also reach 82%

A Novel Dynamic Absorber with Variable Frequency and Damping

Smoothness and discontinuous (SD) oscillator is a nonlinear oscillator with the variable frequency, whose frequency can be varied with the smoothing parameter. However, how to adjust the smoothing parameter has not been solved in the actual device. In this paper, the shape memory alloy (SMA) is introduced into the SD oscillator to form the SMA-SD oscillator to adjust the smoothing parameters. Combining the SMA-SD oscillator with MRF, a nonlinear dynamic vibration absorber (DVA) with variable frequency and damping is designed. The structure and control principle of the designed DVA is studied to achieve the two variable characteristics simultaneously by adjusting the current intensity. Numerical results on a two-degree-of-freedom coupled system show that the proposed DVA can adapt to different working conditions only by adjusting the current intensity

Gaussian Half-Wavelength Progressive Decomposition Method for Waveform Processing of Airborne Laser Bathymetry

In an airborne laser bathymetry system, the full-waveform echo signal is usually recorded by discrete sampling. The accuracy of signal recognition and the amount of effective information that can be extracted by conventional methods are limited. To improve the validity and reliability of airborne laser bathymetry data and to extract more information to better understand the water reflection characteristics, we select the effective portion of the original waveform for further research, suppress random noise, and decompose the selected portion progressively using the half-wavelength Gaussian function with the time sequence of the received echo signals. After parameter optimization, a reasonable and effective reflection component selection mechanism is established to obtain accurate parameters for the reflected components. The processing strategy proposed in this paper reduces the problems of unreasonable decomposition and the reflected pulse peak-position shift caused by echo waveform superposition and offers good precision for waveform decomposition and peak detection. In another experiment, the regional processing result shows an obvious improvement in the shallow water area, and the bottom point cloud is as accurate as the intelligent waveform digitizer (IWD), a subsystem of airborne laser terrain mapping (ALTM). These findings confirm that the proposed method has high potential for application

Effects of conversion from a natural evergreen broadleaf forest to a Moso bamboo plantation on the soil nutrient pools, microbial biomass and enzyme activities in a subtropical area

Converting natural forests to plantations would markedly change soil physiochemical and biological properties, as a consequence of changing plant vegetative coverage and management practices. However, the effects of such land-use change on the soil nutrient pools and related enzymes activities still remain unclear. The aim of this study was to explore the effects of conversion from natural evergreen broadleaf forests to Moso bamboo plantations on the pool sizes and forms of soil N, P and K, microbial biomass, and nutrient cycling related enzyme activities. Soil samples from four adjacent evergreen broadleaf forest-Moso bamboo plantation pairs were collected from a subtropical region in Zhejiang Province, China. The soil organic C (SOC), total N (TN), total P (TP) and total K (TK) concentrations and stocks and different N, P and K forms were measured, and the microbial biomass C (MBC), microbial biomass N (MBN), microbial biomass P (MBP) and four soil enzymes (protease, urease, acid phosphatase and catalase) were determined. The results showed that converting broadleaf forests to Moso bamboo plantations decreased the concentration and stock of SOC but increased those of TK in both soil layers (0-20 and 20-40 cm), and such land-use change increased the concentration and stock of TN and TP only in the 0-20 cm soil layer (P <0.05). This land-use conversion increased the concentrations of NH4+-N, NO3- N, resin-Pi, NaHCO3-P-1, NaOH-P-i, HCl-P-i, available K and slowly available K, but decreased the concentrations of water-soluble organic nitrogen (WSON), NaHCO3-P-o and NaOH-P-o (P <0.05). Further, this land-use change decreased the microbial biomass and activities of protease, urease, acid phosphatase and catalase (P <0.05). In addition, the acid phosphatase activity correlated positively with the concentrations of MBP and NaHCO3-P-o, and the activities of urease and protease correlated positively with the concentrations of MBN and WSON (P <0.01). To conclude, converting natural broadleaf forests to Moso bamboo plantations had positive effects on soil inorganic N, P and K pools, and negative effects on soil organic N and P pools, and on N- and P-cycling related enzyme activities. Therefore, management practices that increase organic nutrient pools and microbial activity are needed to be developed to mitigate the depletion of organic nutrient pools after the land-use conversion.Peer reviewe

Adjustment of Transceiver Lever Arm Offset and Sound Speed Bias for GNSS-Acoustic Positioning

Global Navigation Satellite System&mdash;Acoustic (GNSS-A) positioning is the main technique for seafloor geodetic positioning. A transceiver lever arm offset and sound velocity bias in seawater are the main systematic errors of the GNSS-A positioning technique. Based on data from a sea trial in shallow water, this paper studies the functional model of GNSS-A positioning. The impact of the two systematic errors on seafloor positioning is analysed and corresponding processing methods are proposed. The results show that the offset in the lever arm measurement should be parameterised in the observation equation. Given the high correlation between the vertical lever arm offset and the vertical coordinate of the seafloor station, a sample search method was introduced to fix the vertical offset correction. If the calibration of the sound velocity profiler cannot be ensured, the correction parameter of the sound velocity bias should be solved. According to the refined functional model and corrections, the position of a seafloor station in shallow water can be determined with a precision of better than 1 cm

Impact of ECOM Solar Radiation Pressure Models on Multi-GNSS Ultra-Rapid Orbit Determination

The Global Navigation Satellite System (GNSS) ultra-rapid precise orbits are crucial for global and wide-area real-time high-precision applications. The solar radiation pressure (SRP) model is an important factor in precise orbit determination. The real-time orbit determination is generally less accurate than the post-processed one and may amplify the instability and mismodeling of SRP models. Also, the impact of different SRP models on multi-GNSS real-time predicted orbits demands investigations. We analyzed the impact of the ECOM 1 and ECOM 2 models on multi-GNSS ultra-rapid orbit determination in terms of ambiguity resolution performance, real-time predicted orbit overlap precision, and satellite laser ranging (SLR) validation. The multi-GNSS observed orbital arc and predicted orbital arcs of 1, 3, 6, and 24 h are compared. The simulated real-time experiment shows that for GLONASS and Galileo ultra-rapid orbits, compared to ECOM 1, ECOM 2 increased the ambiguity fixing rate to 89.3% and 83.1%, respectively, and improves the predicted orbit accuracy by 9.2% and 27.7%, respectively. For GPS ultra-rapid orbits, ECOM 2 obtains a similar ambiguity fixing rate as ECOM 1 but slightly better orbit overlap precision. For BDS GEO ultra-rapid orbits, ECOM 2 obtains better overlap precision and SLR residuals, while for BDS IGSO and MEO ultra-rapid orbits, ECOM 1 obtains better orbit overlap precision and SLR residuals

Calibration of Mounted Parameter for Ship-borne 3D Laser Scanning System

Ship-borne 3D laser scanning technology has vital theoretical significance and practical value in marine surveying and mapping.As one of the key steps of ship-borne 3D laser scanning, calibration of mounted parameter is urgent to be solved.This paper proposes a calibration method of mounted parameter without control points for ship-borne 3D laser scanning system.Based on the corresponding points in overlapping area, mounted parameter calibration model of scan system is built by time and spatia registration model of ship-borne 3D laser scanning data.Finally, differential least squares are applied to obtain optimum mounted parameters.Experiments demonstrate the reasonable and effectiveness of this method,the quality of scanning data can be significantly improved

Dual-Color Fluorescent Hydrogel Microspheres Combined with Smartphones for Visual Detection of Lactate

Since it is difficult for human eyes to distinguish between two identical colors with only <15% variation in brightness, mono-color fluorescent hydrogel microspheres have some limitations in the detection of lactate. Herein, we prepared novel dual-color fluorescent hydrogel microspheres, which can achieve hue transformation. Microspheres were prepared by introducing a fluorescent nanoparticle as the reference signal while CdTe QDs were used as the response signal. We used smartphones with image processing software to collect and analyze data. In this way, the signal of lactate was converted to RGB (red, green, and blue) values, which can be quantitatively read. Within 10 to 1500 μM, the R/G values of the microspheres had a linear relationship with the logarithm of the lactate concentration. Moreover, color cards for lactate detection were prepared, from which the color change and concentration of lactate could be easily read by the naked eye. It is worth mentioning that this method was successfully applied to screen patients with hyperlactatemia