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The 5' cap and 3' poly(A) tail of mRNA are known to synergistically stimulate translation initiation via the formation of the cap•eIF4E•eIF4G•PABP•poly(A) complex. Most mRNA sequences have an intrinsic propensity to fold into extensive intramolecular secondary structures that result in short end-to-end distances. The inherent compactness of mRNAs might stabilize the cap•eIF4E•eIF4G•PABP•poly(A) complex and enhance cap-poly(A) translational synergy. Here, we test this hypothesis by introducing intrinsically unstructured sequences into the 5' or 3' UTRs of model mRNAs. We found that the introduction of unstructured sequences into the 3' UTR, but not the 5' UTR, decreases mRNA translation in cell-free wheat germ and yeast extracts without affecting mRNA stability. The observed reduction in protein synthesis results from the diminished ability of the poly(A) tail to stimulate translation. These results suggest that base pair formation by the 3' UTR enhances the cap-poly(A) synergy in translation initiation.

Translating ribosomes unwind mRNA secondary structures by three basepairs each elongation cycle. Despite the ribosome helicase, certain mRNA stem-loops stimulate programmed ribosomal frameshift by inhibiting translation elongation. Here, using mutagenesis, biochemical and single-molecule experiments, we examine whether high stability of three basepairs, which are unwound by the translating ribosome, is critical for inducing ribosome pauses. We find that encountering frameshift-inducing mRNA stem-loops from the E. coli dnaX mRNA and the gag-pol transcript of Human Immunodeficiency Virus (HIV) hinders A-site tRNA binding and slows down ribosome translocation by 15-20 folds. By contrast, unwinding of first three basepairs adjacent to the mRNA entry channel slows down the translating ribosome by only 2-3 folds. Rather than high thermodynamic stability, specific length and structure enable regulatory mRNA stem-loops to stall translation by forming inhibitory interactions with the ribosome. Our data provide the basis for rationalizing transcriptome-wide studies of translation and searching for novel regulatory mRNA stem-loops.

It has been studied that mesenchymal stem cells (MSCs)-derived exosomes could suppress tumor growth in nasopharyngeal carcinoma (NPC) and microRNA-181a (miR-181a) could mediate drug resistance in NPC. Focused on this work, the mechanism of human umbilical cord MSCs (hUC-MSCs)-derived exosomal miR-181a was explored in NPC cell progression. NPC tissues and normal tissues were obtained from patients, and miR-181a and KDM5C expression was examined. hUC-MSCs-derived exosomes were extracted, identified and co-cultured with NPC cells (C666-1 and SUNE1). C666-1 cell progression in vitro and/or tumor growth in vivo were examined after incubation with exosomes, miR-181a or lysine-specific demethylase 5C (KDM5C). miR-181a and KDM5C expression were examined in NPC. miR-181a expression was reduced while KDM5C expression was elevated in NPC. hUC-MSCs-derived exosomes restrained NPC cell growth in vivo and in vitro. Depleting or restoring exosomal miR-181a promoted or delayed NPC cell progression. KDM5C silencing suppressed NPC cell progression. This study concluded that hUC-MSCs-derived exosomal miR-181a retards NPC development via negatively modulating KDM5C, serving as a candidate reference for the therapy of NPC.

Abstract. Conditionals statements are a common and necessary component in natural languages. The research reported in this paper is on a fundamental question about singular conditionals. Is there an adequate account of people’s truth, falsity, and credibility (probability) judgments about these conditionals when their antecedents are false? Two experiments examined people’s quantitative credibility ratings and qualitative truth and falsity judgments for singular conditionals, if p then q, given false antecedent, not-p, cases. The results demonstrate that, when relevant knowledge about the conditional probability of q given p, P( q|p), is available to participants in not-p cases, they tend to make credibility ratings based on P( q|p), and to make “true” (or “false”) judgments at a high (or low) level of these credibility ratings. These findings favor the Jeffrey table account of these conditionals over the other existing accounts, including that of the de Finetti table.

With the development of modern aerospace technology, radar target altitude become lower and lower, so the low-altitude targets quick and accurate location defense system has become urgent to solve. The radar was looking down on the general situation of low altitude targets, if the Earth is considered as a sphere in the wave refraction correction, it will have great error. In this paper, the radar measurement parameters and geodetic coordinate conversion to space coordinate, the calculation method is given with the radar beam radiation at any point corresponding to the Earth's radius.

The measuring accuracy of atmospheric refractivity directly affects the precision of radar refraction error correction and atmospheric duct measurement. Because the conventional gas sensor can not accurately measure the atmospheric refractivity, the sensor–high Q microwave resonator that can accurately measure the atmospheric refractivity on-line is proposed basing on the principle that resonant frequency will change as different medium pass through the microwave resonator. Many aspects of the microwave resonator, such as the size, electromagnetic coupling ventilation material and processing technology are designed to ensure the measuring accuracy of the sensor. The results of experiment show that the sensor has the advantages of higher measuring accuracy and faster measuring speed, and the measuring accuracy of atmospheric refractivity can meet the request of radar refraction error correction and the atmospheric duct measurement.

Open quantum systems interacting with structured environments is important and manifests non-Markovian behavior, which was conventionally studied using a quantum trajectory stochastic method. In this paper, by dividing the effects of the environment into two parts, we propose a deterministic method without using a quantum trajectory. This method is more efficient and accurate than the stochastic method in most Markovian and non-Markovian cases. We also extend this method to the generalized Lindblad master equation.

In order to improve the accuracy of radar measurement, mobile radar waves are generally carried out refraction error correcting. At present, there are two refraction error correction methods. One method has high accuracy, but the calculation speed of it is too slow to apply real-time calculation. The other one is very fast, but the use of the simplified model makes the accuracy very poor, so it is hard to meet the needs of future high-precision measurement and control. Therefore, this paper proposes the fast algorithm of wave refraction error in a mobile radar system, which is based on the meteorological parameters of ground-based, and also inspects the precision. At the same time, it is proved that the fast algorithm can completely take the place of ray tracing method at 4 ° angle of elevation above, and has an important significance in improving the mobile radar measurement accuracy.

For fire detection and alarm system with simple function, positioning difficulties, false positive and false negative in traditional intelligent building, the fire detection and alarm systems based on intelligent neural network have been designed. It can do integrated estimation with a variety of fire detection information detected by the microcontroller, neural network intelligent algorithm was joined in the software design, MATLAB simulation realize multiple synchronous intelligent detection, which effectively detect various types of early fire and reduce the fire.

Control parameter of electronically controlled engine is a critical factor which affects the engine performance. The engine control parameters has been done the bench calibration using the developed electronic control engine calibration development system, the system used open-loop control strategy based on MAP chart. The calibration process of gasoline control parameter is briefly introduced based on electric control system steady-state condition on all terrain vehicle, the engine achieved the stable operation on the bench by experiment. Through engine bench comparison experiment between the installed meticulous calibration electronic control system engine and the original carburetor, to verify its power and torque improved average of 5.9%, fuel consumption decreased by 4.3%.

To improve the accuracy of radar measurement, mobile radar often needs to correct the radio wave refraction error. For the current refraction error correction methods, one has high accuracy but the computing speed is too slow, so it can not be used in real-time calculation, another has high speed, but its accuracy is low because of the use of simplified model, and it is difficult to meet the needs of high precision measurement and control in future. A fast algorithm of radio wave refraction error, which makes use of ground meteorological parameters, is proposed, and its accuracy is tested.

It is a better method to use microwave resonator to measure gas parameters accurately, based on the characteristics that resonant frequency changes along with the different mediums, which pass through the microwave resonator. The energy coupling degree between microwave cavity resonator and external waveguide affects the performance and precision directly. According to the propagation characteristic of electromagnetic wave in waveguide, a novel coupling model has been established. By analyzing electromagnetic energy of resonance coupling hole and waveguide coupling face, we choose optimum coupling match method, to make the resonance export the maximal electromagnetic energy, and avoid owing to electromagnetic smaller energy due to the increasing demands for circuit system. Simulation experimental results show that the best coupling of electromagnetic energy can be get only at the position where the waveguide center is departure a certain distance from the resonance coupling hole center, not the superposition between the resonance coupling hole center and waveguide center.

In mobile communication, the covering range and the interference is considered to be so important in each base station that it is necessary to know the regional transmission loss. Currently, there is a high margin of error in actual transmission loss model on the sea. This paper presents a propagation loss model. After doing many experiments, the results show that the error between the models predicted levels and measured levels of models is less than 3dB within the radio line of sight. Once over the radio line of sight, the model prediction accuracy will decrease, which is to be considered the Earth's curvature on the impact of propagation loss.

A novel data acquisition and analysis system has been developed for a surface plasmon resonance (SPR) bioanalyzer, which is based on the use of TSPR1k23 biosensor and composed of a microflow cell, a clamp, and a photoelectronic conversion device. A virtual instrument consists of a computer-based platform that is equipped with powerful application software and cost-effective hardware, which outperform the functions of the instrument for obtaining data from the biosensor. In this system, The PIC24HJ32GP302 microprocessor interfacing with a 16bit ADS8326 analog-to-digital converter is used to transform the photoelectronic signals from the CCD photodetector and the communication between the microprocessor and the computer is achieved through the USB-RS232C serial port converter adapter designed by CP2102 chip. The system software for describing the biomolecular interaction and sample concentration is programmed with LabVIEW graphic programming environment, which be mainly introduced in this paper. The software modules reveal important information for sensor golden surface that SPR signal can be identified as well and the values of response unit (RU), refractive index (RI) and sample concentration can be computed correspondingly. Because it is based on computer, the system's function is flexibly defined and meets user's requirement easily. This data acquisition and analysis system is more directviewing, economical, high efficient, friendly in comparison with other data acquisition and analysis system based on VB language or assemble language. Some biochemistry experimental results show that it is a highly performance data acquisition and analysis system.

Entanglement dynamics for a couple of two-level atoms interacting with independent structured reservoirs is studied using a non-perturbative approach. It is shown that the revival of atom entanglement is not necessarily accompanied by the sudden death of reservoir entanglement, and vice versa. In fact, atom entanglement can revive before, simultaneously or even after the disentanglement of reservoirs. Using a novel method based on the population analysis for the excited atomic state, we present the quantitative criteria for the revival and death phenomena. For giving a more physically intuitive insight, the quasimode Hamiltonian method is applied. Our quantitative analysis is helpful for the practical engineering of entanglement., Comment: 10 pages and 4 figures