The effect of IF(Intermediate Frequency)analog AGC on QPSK/OQPSK signal detection is evaluated for LEO satellite system where Doppler drift,large dynamic range of signal power and low Eb/No condition are difficult to ...
The effect of IF(Intermediate Frequency)analog AGC on QPSK/OQPSK signal detection is evaluated for LEO satellite system where Doppler drift,large dynamic range of signal power and low Eb/No condition are difficult to deal with. The way of setting reference value of logarithmic power based AGC is *** accumulation and non-coherent accumulation are used for detecting,while signal's PDF and performance *** times are derived mathematically. Experiment shows that with 60KHz Doppler offset,Eb/No=0dB under QPSK/OQPSK,only 16bits was consumed to detect the signal with 99.9%detection probability and 0.1%false alarm probability.
ThefecC gene encoding a putative iron (III) dicitrate transporter was cloned from nitrogen-fixing cyanobacteriumAnabaena sp. PCC 7120, and inactivated. The mutant grows normally in medium with NO 3 ? , NH 4 + or witho...
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ThefecC gene encoding a putative iron (III) dicitrate transporter was cloned from nitrogen-fixing cyanobacteriumAnabaena sp. PCC 7120, and inactivated. The mutant grows normally in medium with NO 3 ? , NH 4 + or without combined nitrogen. But in iron-deficient medium, the mutant grows slowly. Photosynthetic properties were compared between the mutant and the wildtype strain, the content of photosynthetic pigments in the mutant is lower than that of the wild-type. The results of RT-PCR experiments show that thefecC gene is expressed under iron-deficient conditions, but is not expressed under iron-replete conditions. These results revealed thatfecC gene product is required for optimal growth under iron-deficient conditions inAnabaena sp. PCC 7120.
Key words Anabaena sp. PCC 7120 - fecC - iron deficiency - photosynthetic properties - expression
CLC number Q 933
Foundation item: Supported by the National Natural Sciences Foundation of China (30070154), the Frontier Science Projects Program of the Institute of Hydrobiology, the Chinese Academy of Sciences (220316), State Key Project on Cyanobacterial Bloom Control in Lake Dianchi (K99-05-35-01)
Biography: XU Wen-liang (1974-), male, Ph. D, research direction: molecular genetics of cyanobacteria.
A radio access protocol, which can be applied to low earth orbit satellite and cellular internet access, is proposed by ZOHAR N and HANOCH L in their paper in 2001[1]. In their scheme, an access probability is compute...
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A radio access protocol, which can be applied to low earth orbit satellite and cellular internet access, is proposed by ZOHAR N and HANOCH L in their paper in 2001[1]. In their scheme, an access probability is computed by the central station, according to the load on shared channels. The focus in this paper is on the impact of load estimation error on the channel throughput, channel delay, and the equilibrium of the system. At the end of this paper, a conclusion is drawn that higher estimation makes the channel more efficient, time delay more short, and backlogged users less at the equilibrium point than lower estimation does.
The effect of iron deficiency on heterocyst differentiation and some physiological properties of the filamentous cyanobacterium Anabaena sp. PCC 7120 was investigated. Under moderate iron limitation conditions, ac...
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The effect of iron deficiency on heterocyst differentiation and some physiological properties of the filamentous cyanobacterium Anabaena sp. PCC 7120 was investigated. Under moderate iron limitation conditions, achieved by addition of iron chelator 2,2′\|Dipyridyl (<80 μmol/L) led to delayed heterocyst differentiation, no heterocyst differentiation was observed under severe iron limitation conditions, when the concentration of 2,2′\|Dipyridyl in the medium was more than 100 μmol/L . It seemed that there are certain iron\|regulated genes or operons whose function is to control heterocyst development. In addition, iron deficiency impaired the growth. Low\|iron cells had a decrease in the quantities of pigment content (chlorophyll and phycocyanin content),the whole cell in vivo absorbance spectra confirmed the decrease, the protein electrophoretic profiles revealed that iron\|deficient cells had less protein bands, with the increase of 2,2′\|Dipyridyl ,the protein bands was more and more less. And differently, iron deficiency also caused an increase of ROS (Reactive Oxygen Species)and SOD activity, it suggests that iron deficiency led to oxidative stress, which generally occured under high\|iron conditions.
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