A region within the RAP74 subunit of human transcription factor IIF is critical for initiation but dispensable for complex assembly

(RAP74) and RAP30 subunits. Mutagenic analysis shows that the N-terminal region of RAP74 between L155 (leucine at codon 155) and M177 is important for initiation. Mutants in this region have reduced activity in transcription, but none are inactive. Single amino acid substitutions at hydrophobic residues L155, W164, I176, and M177 have similar activity to RAP74(1–158), from which all but three amino acids of this region are deleted. Residual activity can be explained because each of these mutants forms a complex with RAP30 and recruits RNA polymerase II into the preinitiation complex. Mutants are defective for formation of the first phosphodiester bond from the adenovirus major late promoter but do not appear to have an additional significant defect in promoter escape. Negative DNA supercoiling partially compensates for the defects of TFIIF mutants in initiation, indicating that TFIIF may help to untwist the DNA helix for initiation. Accurate initiation from human pre-mRNA promoters requires the cooperation of general transcription factors and RNA polymerase II (reviewed in references 15, 31, and 38). For promoters containing a TATA box, an ordered in vitro pathway for assembly of an active transcription complex has been defined. TATA-binding protein (TBP) binds to the TA

A Novel Robust Model Predictive Controller for Aerospace Three-Phase PWM Rectifiers

This paper presents a novel Model Predictive Direct Power Control (MPDPC) approach for the pulse width modulation (PWM) rectifiers in the Aircraft Alternating Current Variable Frequency (ACVF) power system. The control performance of rectifiers may be largely affected by variations in the AC side impedance, especially for systems with limited power volume system. A novel idea for estimating the impedance variation based on the Bayesian estimation, using an algorithm embedded in MPDPC is presented in this paper. The input filter inductance and its equivalent series resistance (ESR) of PWM rectifiers are estimated in this algorithm by measuring the input current and input voltage in each cycle with the probability Bayesian estimation theory. This novel estimation method can overcome the shortcomings of traditional data based estimation methods such as least square estimation (LSE), which achieves poor estimation results with the small samples data set. In ACVF systems, the effect on the parameters estimation accuracy caused by the number of sampling points in one cycle is also analyzed in detail by simulation. The validity of this method is verified by the digital and Hard-in-loop simulation compared with other estimation methods such as the least square estimation method. The experimental testing results show that the proposed estimation algorithm can improve the robustness and the control performance of the MPDPC under the condition of the uncertainty of the AC side parameters of the three-phase PWM rectifiers in aircraft electrical power system

Numerical Study on the Influence of Length-Diameter Ratio on the Performance of Dynamic Pressure Oil-Air Separator

In order to study the separation characteristics of the aeroengine dynamic pressure oil-air separator, this paper uses the coupling method of PBM and CFD two-fluid model to study the influencing factors such as cylinder diameter, cylinder length, and other factors on the separator performance. The flow field structure, velocity, gas volume distribution, separation efficiency, and gas and liquid holdup rate in the separator under different operating conditions are analyzed. Combined with the analysis results of the cylinder diameter and the cylinder length, the influence law of length-diameter ratio on separation efficiency is summarized. The optimum length-to-diameter ratio that maximizes the separation performance of the separator is obtained in this research, which provides a reference for the design and improvement of the separator. The results show that, as the diameter of the cylinder increases, the separation efficiency increases first and then decreases. When dsep = 16 mm and dsep = 18 mm, the separator reaches its maximum efficiency, which is about 93%. With the increase of the cylinder length, the separation efficiency first increases and reaches the maximum when l2 = 90 mm and then decreases slowly. When the separator cylinder is either too long or too short, it will cause the separation performance to decrease. There is an optimal aspect ratio. There is an optimal aspect ratio, and the separation performance of the separator is the best when the aspect ratio is between 5 and 6

A clinical study of ultrasound-guided intralesional injection of bleomycin A5 on venous malformation in cervical-facial region in China

ObjectivesTo evaluate the therapeutic outcome of ultrasound-guided intralesional injection of bleomycin A5 on treatment of venous malformation (VM) in cervical-facial region.MethodsSeventy-five patients (32 male, 43 female), ranging in age from 13 to 60 years old, suffering from VM in cervical-facial region were admitted to and treated at our hospital between June 2006 and February 2007. Of all the patients, 54 malformations were located in the facial region, eight in the submental region, 10 in the submandible region, and three in the cervical region; all were treated by ultrasound-guided intralesional injections of bleomycin A5. The size of the lesions ranged from 6 × 9 mm to 32 × 39 mm. Injection of bleomycin A5 on venous malformation was then carried out through the inspection of ultrasonography. Repeated course of bleomycin A5 injection was administrated for larger malformations. The amount was 8 mg each time. The therapeutic interval was two to four weeks. The therapeutic outcome on venous malformation was evaluated by physical examination and ultrasonography with Doppler according to the Shou standards, including four grades; cured, basically cured, improved, and invalid. The complications were also observed during and after injection.ResultsThe duration of follow-up ranged from 6 to 24 months. The average times of treatment were 1.64 times. Among them, 42 patients (56%) received only one time of treatment, 21 (28%) patients received two times, nine (12%) patients received three times, and three (4%) patients received four times. According to criteria of therapeutic outcome, the results showed cured in 63 patients (84%), basically cured in 10 patients (13.33%), improved in two patients (2.67%), and none ineffective. Seventy-one patients (94.67%) had local swelling in injection region for several days and two patients (2.67%) developed temporary dizziness after treatment. There were no other complications recorded.ConclusionsIntralesional injection of bleomycin A5 establishes a promisingly effect way for patients suffering from VM in the cervical-facial region under ultrasound guidance