Natural selection and functional diversification of the epidermal growth factor receptorEGFR family in vertebrates

AbstractBackgroundGenes that have been subject to adaptive evolution can produce varying degrees of pathology or differing symptomatology. ErbB family receptor activation will initiate a number of downstream signaling pathways, such as mitogen-activated protein kinase (MAPK), activator of transcription (STAT), the modulation of calcium channels, and so on, all of which lead to aggressive tumor behavior. However, the evolutionary mechanisms operating in the retention of ErbB family genes and the changes in selection pressures are not clear.ResultsSixty-two full-length cDNA sequences from 27 vertebrate species were extracted from the UniProt protein database, NCBI's GenBank and the Ensembl database. The result of phylogenetic analysis showed that the four ErbB family members in vertebrates might be formed by gene duplication. In order to determine the mode of evolution in vertebrates, selection analysis and functional divergence analysis were combined to explain the relationship of the site-specific evolution and functional divergence in the vertebrate ErbB family. Our results indicate that the acceleration of asymmetric evolutionary rates and purifying selection together were the main force for the production of ErbBs, and positive selections were detected in the ErbB family.ConclusionAn evolutional phylogeny of 27 vertebrates was presented in our study; the tree showed that the genes have evolved through duplications followed by purifying selection, except for seven sites, which evolved by positive selection. There was one common site with positive selection and functional divergence. In the process of functional differentiation evolving through gene duplication, relaxed selection may play an important part

Experimental analysis of super-knock occurrence based on a spark ignition engine with high compression ratio

The super-knock phenomenon is a major obstacle for further improving the power density in SI engines. The objective of this paper is to experimentally investigating the mechanism involved in the occurrence of super-knock. In this work, a high compression ratio (CR = 13) coupled with advanced spark timings were employed to achieving intense or critical thermal-dynamic conditions to easily inducing the super-knock. The results show that super-knock can originate from spark ignition, which is different from previous results regarding pre-ignition. Changing the spark timing super-knock can be induced with very high pressure oscillation at the present high compression ratio. The high compression ratio could generate sufficiently high thermal-dynamic conditions to inducing the abnormal combustion. In this research, four combustion phenomena were observed. The present work indicates that there is a nonlinear relationship between knock intensity and knocking onset in terms of pressure profiles at different cycles. The super-knock or knock phenomena were dominantly induced by spark ignition, which were controlled by the pre-ignition after several cycles. Finally, the analysis of the mechanism of super-knock with severe pressure oscillation was employed based on the thermal explosion theory and cavity resonances. There are two possible auto-ignition combustion modes that can induce the intense pressure oscillation

Vibro-Acoustic Monitoring of Nested Planetary Gear Trains

Gear systems are major components in the modern power transmission system, especially in the automobile industry. In recent years, with the auto transmission function development, more compound gears have been utilized for better transmission speed ratio control and space-saving. The nested planetary gear train is widely applied among the newly designed compound gear trains due to its compactness. However, the nested gear train noise and vibration issue have not been studied extensively. In the current study, the vibrational and acoustical monitoring prototype will be developed to monitor the nested planetary manufacturing accuracy in the production line. Firstly, a novel testing fixture with the vertical and open setup is proposed to be used to monitor the gear, which is different from most gear condition monitoring studies. The open setup allows the accelerometer to be mounted directly on different clutches to monitor both carriers in the nested two-stage gear system closely. The test setup also enables the acoustical array to be implemented. Gear carriers with different pinion faults or damages are tested with both vibrational and acoustical sensors to identify the pinion gear error type and location. The vibrational data are processed with several classical rotating machinery signal processing techniques, including: (1) time synchronous averaging; (2) modulation sideband analysis; (3) modulation sideband modeling; (4) narrowband demodulation. Those techniques are also partially modified to adapt for the nested planetary structure monitoring. The results show that the unground or damaged pinions can be successfully identified and localized. Besides vibrational signal monitoring, an acoustical array is also proposed for noise source visualization and localization of the outer gearset (stage-2). The virtual rotating array (VRA) methods are proposed to de-Ddopperize the rotating source sound signals measured at stationary receivers. The VRA signals are subsequently used as input of the equivalent source based compressive sensing holography for high-resolution localization of the compact rotating sources. Both time-domain VRA and frequency domain VRA methods are studied and further developed for improved computational efficiency in terms of the VRA process. The new developments of the acoustical imaging system for rotating source localization are validated numerically and experimentally. Last but not least, the acoustical imaging system has also been successfully applied to the unground gear condition monitoring in the outer gearset of the nested gear train

The theory and practice in the evolution of trusted computing

Trusted computing (TC) is an emerging technology to enhance the security of various computing platforms by a dedicated secure chip (TPM/TCM), which is widely accepted by both the industrial and academic world. This paper attempts to sketch the evolution of TC from the view of our theoretical and engineering work. In theory, we focus on protocol design and security analysis. We have proposed the first ECDAA protocol scheme based on q-SDH assumption, which highlights a new way to design direct anonymous attestation scheme. In technical evolution, we discuss the key technologies of trust chain, trusted network connection and TC testing and evaluation. We break through several key technologies such as trusted boot, OS measurement and remote attestation, and implement a TC system from TPM/TCM to network. We also design and implement a testing and evaluation system of TC platform, which is the first one put into practical application in China. Finally, with the rapid development of cloud computing and mobile applications, TC is moving toward some new directions, such as the trust in cloud and mobile environments, new TPM standard, and flexible trust execution environment trust establishment method.Trusted computing (TC) is an emerging technology to enhance the security of various computing platforms by a dedicated secure chip (TPM/TCM), which is widely accepted by both the industrial and academic world. This paper attempts to sketch the evolution of TC from the view of our theoretical and engineering work. In theory, we focus on protocol design and security analysis. We have proposed the first ECDAA protocol scheme based on q-SDH assumption, which highlights a new way to design direct anonymous attestation scheme. In technical evolution, we discuss the key technologies of trust chain, trusted network connection and TC testing and evaluation. We break through several key technologies such as trusted boot, OS measurement and remote attestation, and implement a TC system from TPM/TCM to network. We also design and implement a testing and evaluation system of TC platform, which is the first one put into practical application in China. Finally, with the rapid development of cloud computing and mobile applications, TC is moving toward some new directions, such as the trust in cloud and mobile environments, new TPM standard, and flexible trust execution environment trust establishment method

Symmetry and asymmetry from MEMS variable capacitor by nonlinear micro stoppers

Mechanical stoppers in MEMS capacitive systems can dramatically affect electrical performances and result in complicated mechanical dynamic responses. This paper introduces electromechanical coupling nonlinear dynamic responses in MEMS variable dual-capacitor with an effect of nonlinear and asymmetrical stoppers. We found that the capacitance in the electrical circuit system related to the first-order derivative of the output voltage on a load resistor, and the variable dual-capacitor was strongly affected by the coupling of up and down superposition instantaneous electrostatic force and limited space by the length of nonlinear stoppers. The numerical calculation results and the experimental results in our analysis based on our system had a good agreement, and the numerical simulation results presented rich nonlinear impacts dynamic responses through the imposed voltage and the height of stoppers in MEMS variable dual-capacitive device. The device in operation cannot reach the 0.6 time's initial gap due to small forcing amplitude (1.026 g). However, we observed that the movable plate and stoppers (across the 0.6 time's initial gap) had fierce impacts due to big forcing amplitude (4 g) on to the device. With asymmetric stopper each impact, we also concluded that the movable plate would experience attenuations of the displacement until the moment to the next impacts. Moreover, the height of stoppers can not only result in complicated dynamic motion of the movable plate, but also can modulate a voltage of the fixed plate with its asymmetry structure

Analysis of the impact of traction power supply system containing new energy on the power quality of the power system

The access of new energy in the traction power supply system (TPSS) can not only realize low-carbon operation of electrified railroads in the western region, but also promote elimination on the spot of new energy. However, it also brings a series of power quality problems to the power system. The objective of this study was to analyze the impact of TPSS containing new energy on the power quality of the power system. Firstly, a probabilistic model of TPSS containing new energy is established by means of the randomness of locomotive and new energy output power; Secondly, it is analyzed theoretically that the impact of new energy access to the TPSS on the voltage imbalance, power factor and voltage deviation of power system; Finally, Monte Carlo simulation is applied to calculate the probabilistic load flow to obtain the evaluation index, which is used to quantify the impact of new energy access on the power system quality. The results show that the matching degree of new energy output power and load power has a significant impact on the voltage imbalance, power factor and voltage deviation of the power system, while the access location has a smaller impact on the above indicators