Search

Twin-field quantum key distribution (TFQKD) overcomes the linear rate-loss limit, which promises a boost of secure key rate over long distance. However, the complexity of eliminating the frequency differences between the independent laser sources hinders its practical application. We analyzed and determined the frequency stability requirements for implementing TFQKD using frequency-stabilized lasers. Based on this analysis, we proposed and demonstrated a simple and practical approach that utilizes the saturated absorption spectroscopy of acetylene as an absolute reference, eliminating the need for fast frequency locking to achieve TFQKD. Adopting the 4-intensity sending-or-not-sending TFQKD protocol, we experimentally demonstrated the TFQKD over 502, 301, and 201 km ultralow-loss optical fiber, respectively. We expect this high-performance scheme will find widespread usage in future intercity and free-space quantum communication networks.

From 2011 to 2012 in Urumqi, blood samples of 308 household dogs and of 110 stray dogs were collected from three pet hospitals and a stray dog shelter, respectively. Serum anti-Toxoplasma gondii IgG was detected by ELISA. The results showed that the overall seropositive rate was 31.8% (133/418). The rate in household dogs and stray dogs was 29.9% (92/308) and 37.3% (41/110), respectively (P>0.05). Among 308 household dogs, the positive rate in males and females was 27.0% (41/152) and 32.7% (51/156), respectively (P>0.05). The seropositive rate in dogs <1 years old, 1-2 years old, and more than 2 years old was 27.1% (32/118), 30.2% (29/96), and 33.3% (31/94), respectively (P>0.05). The results revealed a high seroprevalence of T. gondii infection in dogs in Urumqi.

Objective: To determine the prevalence and evaluate the risk factors of canine echinococcosis based on a field survey of dog infections with Echinococcus granulosus and E. multilocularis in Chalong, Kalong, Dade and Chazha Townships in a district of Ganzi County, Sichuan Province, China., Method: Questionnaire associated with the acquisition of canine echinococcosis was administered to dog owners. Stray dogs were examined post-mortem and rectal faeces at necropsy were collected to validate a copro-antigen ELISA. Owned dogs were screened for Echinococcus spp. infection in faeces using the genus specific copro-ELISA and the effectiveness of dog treatment was assessed. Chi-square and one-way ANOVA were used for statistical analysis., Results: The prevalence of Echinococcus spp. infection at necropsy in stray dogs was 60.9% (14/23) in 2000; E. multilocularis infection accounted for 34.8% (8/23) and E. granulosus for 26.1% (6/23). The specificity of the copro-ELISA was 80.0% and the sensitivity was 92.3%, compared with the results at necropsy. Fifty percent of owned dogs (290/580) tested was copro-antigen positive at the beginning of the project in 2000, which decreased to 17% (99/580) in the same cohort of owned dogs after praziquantel treatment (5 mg/ kg) at 6-monthly period from 2003 to 2005. Analysis for risk factors associated with copro-antigen positive dogs showed that the never tethered dogs had a higher rate (40.4%, 65/161) than dogs tethered during the day (32.3%, 109/337), or tethered at night [29.2% (21/72)], or those always tethered [20%(2/10)](P<0.01). Dogs that their owners lacked hydatid transmission knowledge [38.1% (121/318)] and did not have de-worming practice [47.7% (92/193)] had significantly higher copro-antigen positive rate than those dogs that their owners knew relevant knowledge [28.6% (75/262)] and were dewormed regularly [20.4% (79/387)](P<0.05 and P<0.01). There was no correlation between the prevalence and dog sex or age or the varieties of livestock that the owner raised., Conclusion: Local dogs show high prevalence with both E. granulosus and E. multilocularis. The copro-ELISA can be used to detect infection of Echinococcus in dogs. Allowing dogs to roam, lack of the basic knowledge of hydatid disease transmission and no de-worming practice for dogs are significant factors for the transmission of canine echinococcosis.