Key space enhancement of optical chaos secure communication: chirped FBG feedback semiconductor laser

Optical chaos communication has advantages of high speed and long transmission distance. Unfortunately, the key space of the traditional transceiver, i.e. semiconductor laser with mirror feedback, is limited due to the time delay signature. In this paper, we propose and numerically demonstrate a key space enhancement by using semiconductor laser with optical feedback from a chirped fiber Bragg grating (FBG). The chirped FBG feedback can make feedback delay a key parameter by eliminating the time delay signature. Moreover, the grating dispersion and center frequency can also be used as new keys. As a result, the dimension of key space is increased. By taking a bidirectional communication scheme as an example, numerical results show that the key space is raised by 2⁴⁴ times as against mirror feedback with a data rate of 2.5 Gb/s and a coupling strength of 0.447. As the coupling strength decreases, the key space increases due to the fact that chaos synchronization becomes more sensitive to parameter mismatch.

Molecular characterization and phylogenetic analysis of Taenia multiceps from China

Taenia multiceps, one of the most widely distributed zoonotic tapeworm parasites, is able to parasitize the small intestine of canids. The metacestode of T.multiceps is fatal to ruminants and causes important economic losses in livestock. However, molecular characteristics of T.multiceps and coenurus in China are still unclear. In this study, 36 goat isolates of the coenurus stage and 18 dog isolates of the adult stage of T.multiceps were obtained from three geographical areas in China and the isolated parasite above were analyzed by amplifying the partial of cytochrome coxidase subunit 1(pcox1), 12S ribosomal RNA (12S rRNA) from mitochondrial DNA (mtDNA) regions and an internal transcribed spacer (ITS) of ribosomal DNA (rDNA). These DNA sequences obtained from T.multiceps and coenurus were employed to evaluate the nucleotide diversity and confirm the relationship between T.multiceps and coenurus. Sequences variation were 0-1.4%, 0-1.5%, 0-4.2% for pcox1, 12S rRNA and ITS, respectively, among T.multiceps and coenurus isolates obtained in this study. In Sichuan province, sequence variations for Coenurus cerebralis isolated from Yaan city were 0-1.4% for pcox1, 0-1.0% for 12S rRNA and 0-2.1% for ITS. In Hunan province, variations were 0-1.0%, 0-1.5% and 0-3.3% for corresponding genes for non-coenurus cerebralis isolated from Changsha city, while variations of T.multiceps isolates from Xiangxi autonomous prefecture were 0-1.0%, 0-1.1% and 0-3.4% for pcox1, 12S rRNA and ITS, respectively. Phylogenetic analysis based on pcox1 sequences indicated that all cerebral and noncerebral metacestodes belong to T.multiceps. These results provide reference values for future molecular epidemiological and biological study on T.multiceps in dogs and intermediate hosts.

[Role of aquaporin-4 in the change of interstitial fluid drainage in Alzheimer's disease]

OBJECTIVE

To observe the characteristics of the interstitial fluid (ISF) drainage in the Alzheimer's disease (AD) rats through magnetic resonance imaging (MRI) tracer gadolinium-diethylene triamine pentacetic acid (Gd-DTPA)spread in the brain extracellular space (ECS) and to discuss the role of aquaporin-4 (Aqp4) in the AD.

METHODS

Wild type SD rats (300-350 g) and Aqp4 gene knock out (Aqp4^-/-) SD rats (300-350g) were divided into Sham group, AD group, Aqp4^-/--Sham group and Aqp4^-/--AD group. Sham group and Aqp4^-/--Sham group were injected with saline by intraperitoneal each day for 6 weeks, and the AD group and Aqp4^-/--AD group were injected with D-galactose by intraperitoneal each day for 6 weeks. MRI tracer Gd-DTPA (10 mmol/L, 2 μL) was injected into the hippocampus of the rats. MRI scan was performed at the end of 0.5 h, 1.5 h, 1 h, 2 h, and 3 h to observe the dynamic distribution of the Gd-DTPA in the hippocampus and the diffusion rate D^*, clearance rate k' and half-life t_1/2 measured.

RESULTS

The diffusion rate D* in Sham group was (2.66±0.36)×10^-6 mm2/s, the diffusion rate D^* in AD group was (2.72±0.62)×10-6 mm²/s, the diffusion rate D^* in Aqp4^-/--Sham group was (2.75±0.47)×10^-6 mm²/s, the diffusion rate D^* in Aqp4^-/--AD group was (2.802±0.55)×10^-6 mm²/s, and there was no statistically significant difference in the four groups (One-Way ANOVA, P>0.05).The clearance rate k' in Sham group was (4.57±0.14)×10^-4/s, the clearance rate k' in AD group was (3.68±0.22)×10^-4/s, the clearance rate k' in Aqp4^-/--Sham group was (3.17±0.16)×10^-4/s, the clearance rate k' in Aqp4^-/--AD group was (2.59±0.19)×10^-4/s, and there was significant difference in the four groups (One-Way ANOVA, P<0.05). The half-life t_1/2 in Sham group was (0.67±0.12) h, the half-life t_1/2 in AD group was (0.88±0.08) h, the half-life t_1/2 in Aqp4^-/--Sham group was (1.12±0.15) h, the half-life t_1/2 in Aqp4^-/--AD group was (1.58±0.11) h, and there was significance difference in the four groups(one-way ANOVA,P<0.05).

CONCLUSION

The ISF drainage is slow after AD and the loss of Aqp4 in the AD makes the ISF drainage obviously slow down, Aqp4 plays an important role in AD to remove the metabolism of waste out of the brain.

Response to selection for time interval between ovipositions in the hen

Data were collected from seven generations of selection for reduced time interval between oviposition in a line of Single Comb White Leghorns. This study involved 151 sires, 539 dams, and 2100 female progeny. Oviposition time was measured from 174 to 280 days of age. The only deliberate selection practiced was for reduced oviposition time interval. The mating system was random with the restriction of full or half sib matings. The reduction in oviposition time interval has been 73 minutes or 4.8 percent. There were no significant changes for total egg number, body weight or age at first egg. Rate of lay after reaching 50 percent production to 280 days has increased (P less than .07). Egg weight has declined five percent. Heritability estimates for intra-clutch time interval from correlations were .33 +/- .08, .36 +/- .09 and .35 +/- .15 by sire, dam, and combined components, respectively, .36 +/- .15 by regression of offspring on dam and .39 for realized. The magnitude of the selection differential decreased, over time. The genetic correlation of time interval with early production (280 days) was --.43 +/- .13, and with total egg production (500 days) was .20 +/- .27. The genetic correlations of time interval with egg weight and age at first egg were high and positive; and with body weight, it was negative. The increase in clutch size and the days between clutches during the time of this study were both highly significant.