Systematic analysis of factors determining efficiency in discrimination of a point substitution (SNP) within specific DNA sequences was carried out in the context of hybridization approach. There are two types of sele...Systematic analysis of factors determining efficiency in discrimination of a point substitution (SNP) within specific DNA sequences was carried out in the context of hybridization approach. There are two types of selectivity that are critical for the rational design of highly specific oligonucleotides probes. The first type is the real selectivity of hybridization (fa) that is the ratio of association degrees of targets with an oligonucleotide probe upon the perfect and imperfect complex formation. This type of selectivity reflects the level of discrimination between matched and mismatched signals, which is determined both by experimental conditions and the thermodynamics of oligonucleotide hybridization. The second parameter characterizing the efficiency of SNP discrimination is the limit selectivity of hybridization, which determines the utmost value of fa at a given temperature. This value can be calculated as the ratio of corresponding equilibrium association constants of perfect and imperfect complex formation determined purely by thermodynamics. We have shown that the fa function is the most reliable characteristic describing the hybridization selectivity. For the analytical system designed to reveal any type of perturbation in DNA (e.g. SNP or modification), there is usually a temperature at which fa has its maximum value. The dependency of the fa maximum on different experimental parameters as well as the structural characteristics of a probe are described in details. The results allowed us to postulate points of principle to rationally design the most selective probes on the basis of oli- gonucleotides or their derivatives.展开更多
How to obtain accurate channel state information(CSI)at the transmitter with less pilot overhead for frequency division duplexing(FDD) massive multiple-input multiple-output(MIMO)system is a challenging issue due to t...How to obtain accurate channel state information(CSI)at the transmitter with less pilot overhead for frequency division duplexing(FDD) massive multiple-input multiple-output(MIMO)system is a challenging issue due to the large number of antennas. To reduce the overwhelming pilot overhead, a hybrid orthogonal and non-orthogonal pilot distribution at the base station(BS),which is a generalization of the existing pilot distribution scheme,is proposed by exploiting the common sparsity of channel due to the compact antenna arrangement. Then the block sparsity for antennas with hybrid pilot distribution is derived respectively and can be used to obtain channel impulse response. By employing the theoretical analysis of block sparse recovery, the total coherence criterion is proposed to optimize the sensing matrix composed by orthogonal pilots. Due to the huge complexity of optimal pilot acquisition, a genetic algorithm based pilot allocation(GAPA) algorithm is proposed to acquire optimal pilot distribution locations with fast convergence. Furthermore, the Cramer Rao lower bound is derived for non-orthogonal pilot-based channel estimation and can be asymptotically approached by the prior support set, especially when the optimized pilot is employed.展开更多
In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8...In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8/QPSK-OFDM signal for uplink transmission is successfully proposed and experimentally presented in a full-duplex PON based on OFDM system. Here, for the uplink, in order to unit management of the optical line terminal (OLT) and reduce cost, the optical source functioned as the optical subcarrier at optical network units (ONUs) is from OLT in the central station. Moreover, there is an external cavity laser (ECL) with center frequency of 193.2 THz not only employed as optical modulated signal but also acted as LO signal. Our simulation results show that bit error ratio (BER) under hardware detection forward error correction has been successfully gained after 20 km of SSMF transmission. It is observed that the receiver sensitivity of multilevel PSK (M-PSK) is obviously larger than that of the M-QAM in this measurement scheme.展开更多
文摘Systematic analysis of factors determining efficiency in discrimination of a point substitution (SNP) within specific DNA sequences was carried out in the context of hybridization approach. There are two types of selectivity that are critical for the rational design of highly specific oligonucleotides probes. The first type is the real selectivity of hybridization (fa) that is the ratio of association degrees of targets with an oligonucleotide probe upon the perfect and imperfect complex formation. This type of selectivity reflects the level of discrimination between matched and mismatched signals, which is determined both by experimental conditions and the thermodynamics of oligonucleotide hybridization. The second parameter characterizing the efficiency of SNP discrimination is the limit selectivity of hybridization, which determines the utmost value of fa at a given temperature. This value can be calculated as the ratio of corresponding equilibrium association constants of perfect and imperfect complex formation determined purely by thermodynamics. We have shown that the fa function is the most reliable characteristic describing the hybridization selectivity. For the analytical system designed to reveal any type of perturbation in DNA (e.g. SNP or modification), there is usually a temperature at which fa has its maximum value. The dependency of the fa maximum on different experimental parameters as well as the structural characteristics of a probe are described in details. The results allowed us to postulate points of principle to rationally design the most selective probes on the basis of oli- gonucleotides or their derivatives.
基金supported by the National Natural Science Foundation of China(61671176 61671173)the Fundamental Research Funds for the Center Universities(HIT.MKSTISP.2016 13)
文摘How to obtain accurate channel state information(CSI)at the transmitter with less pilot overhead for frequency division duplexing(FDD) massive multiple-input multiple-output(MIMO)system is a challenging issue due to the large number of antennas. To reduce the overwhelming pilot overhead, a hybrid orthogonal and non-orthogonal pilot distribution at the base station(BS),which is a generalization of the existing pilot distribution scheme,is proposed by exploiting the common sparsity of channel due to the compact antenna arrangement. Then the block sparsity for antennas with hybrid pilot distribution is derived respectively and can be used to obtain channel impulse response. By employing the theoretical analysis of block sparse recovery, the total coherence criterion is proposed to optimize the sensing matrix composed by orthogonal pilots. Due to the huge complexity of optimal pilot acquisition, a genetic algorithm based pilot allocation(GAPA) algorithm is proposed to acquire optimal pilot distribution locations with fast convergence. Furthermore, the Cramer Rao lower bound is derived for non-orthogonal pilot-based channel estimation and can be asymptotically approached by the prior support set, especially when the optimized pilot is employed.
文摘In the context of next-generation optical access networks beyond 10 G, for high SE and flexible dynamic bandwidth allocation (DBA), the scheme of hybrid 64/16/4QAM-OFDM signal for downlink transmission and hybrid 16/8/QPSK-OFDM signal for uplink transmission is successfully proposed and experimentally presented in a full-duplex PON based on OFDM system. Here, for the uplink, in order to unit management of the optical line terminal (OLT) and reduce cost, the optical source functioned as the optical subcarrier at optical network units (ONUs) is from OLT in the central station. Moreover, there is an external cavity laser (ECL) with center frequency of 193.2 THz not only employed as optical modulated signal but also acted as LO signal. Our simulation results show that bit error ratio (BER) under hardware detection forward error correction has been successfully gained after 20 km of SSMF transmission. It is observed that the receiver sensitivity of multilevel PSK (M-PSK) is obviously larger than that of the M-QAM in this measurement scheme.
