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Introduction: Coronavirus disease 2019 (COVID-19) was declared a global pandemic in March 2020. Since then, several studies have found COVID-19 patients with recurrent viral polymerase chain reaction (PCR) positivity. Methods: On May 6, 2021, an exhaustive literature search of the Web of Science, PubMed, Cochrane Library, Chinese National Knowledge Infrastructure databases, Embase, Wan Fang Data, VIP database, Sinomed database, BioRxiv, MedRxiv, and Research Square was conducted to find describing the laboratory indicators of recurrent and non-recurrent viral PCR positivity in patients with COVID-19. The data were statistically analyzed using STATA version 15.0. Results: In total, 22 studies—comprising 5154 laboratory-confirmed COVID-19 cases—were included in the analyses. Patients with less severe COVID-19 illness (i.e. those clinically classified as mild or common-type) seemed to exhibit recurrent PCR positivity more commonly than patients with more severe illness (i.e. those classified as severe or critical). There were also significant differences between the two groups in terms of the rates of headaches and dizziness, in addition to the levels of aspartate aminotransferase, C reactive protein, interleukin-6, and lactate dehydrogenase. Further, there were variations in the ratio of CD4+ T cells/CD8+ T cells on admission to the hospital. Conclusion: In comparison to COVID-19 patients with non-recurrent viral PCR positivity, patients with recurrent virus PCR positivity seem to experience more severe immune function suppression upon hospital admission.

SummaryBackgroundThe SARS-CoV-2 B.1.1.7 variant which was first identified in the United Kingdom (U.K.) has increased sharply in numbers worldwide and was reported to be more contagious. On January 17, 2021, a COVID-19 clustered outbreak caused by B.1.1.7 variant occurred in a community in Daxing District, Beijing, China. Three weeks prior, another non-variant (lineage B.1.470) COVID-19 outbreak occurred in Shunyi District, Beijing. This study aimed to investigate the clinical features of B.1.1.7 variant infection.MethodsA prospective cohort study was conducted on COVID-19 cases admitted to Ditan hospital since January 2020. Data of 74 COVID-19 cases from two independent COVID-19 outbreaks in Beijing were extracted as study subjects from a Cloud Database established in Ditan hospital, which included 41 Shunyi cases (Shunyi B.1.470 group) and 33 Daxing cases (Daxing B.1.1.7 group) that have been hospitalized since December 25, 2020 and January 17, 2021, respectively. We conducted a comparison of the clinical characteristics, RT-qPCR results and genomic features between the two groups.FindingsCases from Daxing B.1.1.7 group (15 [45.5%] male; median age, 39 years [range, 30.5, 62.5]) and cases from Shunyi B.1.470 group (25 [61.0%] male; median age, 31 years [range, 27.5, 41.0]) had a statistically significant difference in median age (P =0.014). Seven clinical indicators of Daxing B.1.1.7 group were significantly higher than Shunyi B.1.470 group including patients having fever over 38°C (14/33 [46.43%] in Daxing B.1.1.7 group vs. 9/41 (21.95%) in Shunyi B.1.470 group [P = 0 .015]), C-reactive protein ([CRP, mg/L], 4.30 [2.45, 12.1] vs. 1.80, [0.85, 4.95], [P = 0.005]), Serum amyloid A ([SAA, mg/L], 21.50 [12.50, 50.70] vs. 12.00 [5.20, 26.95], [P = 0.003]), Creatine Kinase ([CK, U/L]), 110.50 [53.15,152.40] vs. 70.40 [54.35,103.05], [P = 0.040]), D-dimer ([DD, mg/L], 0.31 [0.20, 0.48] vs. 0.24 [0.17,0.31], [P = 0.038]), CD4+ T lymphocyte ([CD4+ T, mg/L], [P = 0.003]), and Ground-glass opacity (GGO) in lung (15/33 [45.45%] vs. 5/41 [12.20%], [P =0.001]). After adjusting for the age factor, B.1.1.7 variant infection was the risk factor for CRP (P = 0.045, Odds ratio [OR] 2.791, CI [1.025, 0.8610]), SAA (0.011, 5.031, [1.459, 17.354]), CK (0.034, 4.34, [0.05, 0.91]), CD4+ T (0.029, 3.31, [1.13, 9.71]), and GGO (0.005, 5.418, [1.656, 17.729]) of patients. The median Ct value of RT-qPCR tests of the N-gene target in the Daxing B.1.1.7 group was significantly lower than the Shunyi B.1.470 group (P=0.036). The phylogenetic analysis showed that only 2 amino acid mutations in spike protein were detected in B.1.470 strains while B.1.1.7 strains had 3 deletions and 7 mutations.InterpretationClinical features including a more serious inflammatory response, pneumonia and a possible higher viral load were detected in the cases infected with B.1.1.7 SARS-CoV-2 variant. It could therefore be inferred that the B.1.1.7 variant may have increased pathogenicity.FundingThe study was funded by the National Key Research and Development Program (grant nos.2020YFC0846200 and 2020YFC0848300) and National Natural Science Foundation of China (grant no. 82072295).

Background Severe fever with thrombocytopenia syndrome is caused by infection with the severe fever with thrombocytopenia syndrome virus. Methods Between April 2011 and December 2019, data on consecutive patients who were diagnosed with severe fever with thrombocytopenia syndrome were prospectively collected from five medical centers in China. The score of the death risk model was correlated with the platelet-to-lymphocyte ratio and the neutrophil-to-lymphocyte ratio. Multivariable Cox analyses were used to identify the independent factors associated with mortality. Results During the study period, 763 patients were diagnosed with severe fever with thrombocytopenia syndrome; 415 of these patients were enrolled in our study. We found that the neutrophil-to-lymphocyte ratio of the group that died was significantly higher on admission (P=0.007) than that of the group that survived, and the neutrophil-to-lymphocyte ratio showed a positive correlation with the score of the death risk model. Multivariate Cox regression suggested that a neutrophil-to-lymphocyte ratio greater than 5.4 was an independent risk factor for survival time (HR=6.767, P=0.011). Platelet-to-lymphocyte ratio did not show a special role in this study. Conclusions A neutrophil-to-lymphocyte ratio greater than 5.4 can increase the risk of death and decrease the survival time of patients. In summary, the neutrophil-to-lymphocyte ratio provides a supplementary means for effectively managing severe fever with thrombocytopenia syndrome (SFTS).

Severe hemorrhagic fever disease is caused by severe fever with thrombocytopenia syndrome virus (SFTSV) infection, which belongs to the Phlebovirus genus in the Bunyaviridae family. A comprehensive literature search of PubMed, Web of Science, Embase, Cochrane Library, Chinese National Knowledge Infrastructure databases, Wan Fang Data, Sinomed Database, and VIP database was conducted for articles which have described the clinical manifestation of deceased patients. Data from selected studies were pooled by using STATA VERSION 15.0 software. Finally, 29 articles comprising 4717 laboratory-confirmed SFTSV cases were included in this analysis. We found there were significant differences between the two groups for fatigue, headache, underlying disease, vomiting, diarrhea, skin bleeding, neurological symptoms, arrhythmia, diffuse intravascular coagulation, and multiple organ failure. There were some significant differences between the fatal and nonfatal groups, and we need to pay more attention to the above symptoms to distinguish between fatal and nonfatal patients.

Background Towards the end of December 2019, the Wuhan health commission declared an outbreak of clusters of pneumonia in patients. Sequencing indicated that this disease (COVID-19) was caused by a novel coronavirus (SARS-CoV-2). The outbreak of COVID-19 is currently still underway. Methods We recruited 75 SARS-CoV-2 infected patients admitted to the Center of Infectious Disease division 2 of Beijing Ditan Hospital from Jan 20 to Mar 20, 2020. Epidemiological, demographic, clinical, radiological features, laboratory data were analyzed. Results Of the 75 patients, 42(56%) patients were male and 33(44%) patients were female. The mean age of all patients was 41.5 ± 19.4 years. Male patients were more likely to become severe. There were 9 family clusters accounted for 44 patients. Patients classified as being severe had a higher frequency of fever upon admission than patients classified as moderate cases. For moderate patients, the median duration of viral shedding was 25(9.5, 42) days (range 1–63 days) from the first positive nucleic acid test compared to 14(9, 21.25) days (range 2–62 days) for severe cases. The difference between the two groups was statistically significant (p = 0.041). Cox regression analyses indicated that disease status and CRP were the factors that affect the duration of viral shedding. Virus clearance was significantly faster in severe patients compared to moderate patients(p = 0.011), and patients with CRP range in 2–10 times higher than upper limit of normal value had longer duration of viral shedding(p = 0.012). CRP and CD4 + T lymphocyte was negative correlated, and the relationship between CRP and CD4 + T lymphocyte was statistically significant (P = 0.003), with a correlation coefficient of -0.564. During the second week following the onset of illness, severe cases had higher WBC, NEU and CRP, but lower LYM, MON and EOS as compared with moderate cases (all P

On the background of new-type urbanisation, a method that solves the problem and accelerates the development of towns still requires further discussion. This study analyses the state of central towns in the coastal area of Jiangsu Province, China during the implementation of the coastal development strategy, based on the framework of a sustainable city. Results indicate that small towns have experienced improvements in the economy, society, and the environment to different degrees during the past years and have faced the challenges of a lack of comprehensive planning, unreasonable industrial structure, and low capacity and attraction. Some towns have even shrunk during the rapid urbanisation process at the regional level. Thus, this study suggests that (1) systematic planning is necessary to provide guidance to different towns; (2) high-input and polluting enterprises should be avoided in exchange for economic development; (3) coastal region features should be identified and highlighted in the space design; (4) an urban infrastructure system should be established and improved to enhance the capacity of the city; and (5) reform should be explored under the strategy framework for coastal development of the country.

This paper describes a methodology used for the implementation flow of a system on chip circuit containing a complex clock design. The clock generation module contained 2 clock sources and 11 generated clocks. Many of them have interactive relationship. and the 2 clock sources generate the internal clocks in various modes. It uses the combination of bottom-up strategy and top-down strategy to accomplish the clock generation module implementation first, and then finish the whole chip design. This methodology of the solution makes the whole structure of the design distinct, saves a lot of iterative time, and reduces chip power consumption.

Heating induced by electromagnetic field, such as radio-frequency (RF) and microwave is often used in medical application. MW or RF heating is used in hypothermia and hyperthermia treatments. Hypothermia is a clinical condition in which the internal body temperature is lowered below 35 C . RF heating (at 13.56 MHz or 27. 13MHz) offers a fast, efficient and non-invasive method. Hyperthermia in cancer treatment involves heating ofmalignant tumors to 42.5-43CC for a extended period in an attempt to obtain remission. MW(at 2450MHz) is potentially a useful method for heating deep localized tumors. A serious problem with this heating modality involves the accuracy ofmonitoring and controlling the tissue temperature in the presence of a strong EM field. Conventional thermal sensors such as thermocouples and thermistors are all based on a metallic active element which cannot function in a strong EM field environment. Optical fiber fluorescent thermometry is a better technique to show this problem. In this paper we quantify the factors determining the performance ofthis method, some practical considerations also be described