A Comprehensive Analysis on Repeating Fast Radio Bursts

About 900 fast radio burst (FRB) sources have been detected till now, among which 29 FRBs are found to burst out repeatedly. Although a firm connection between at least some FRBs and magnetars has been established, the trigger mechanism and radiation process in these enigma phenomena are still highly controversial. In this study, we build a sample of 16 repeating FRBs from which at least five bursts have been detected, including the most active four repeaters of FRBs 20121102A, 20180916B, 20190520B and 20201124A. Various key parameters of their bursts are collected from the literature, which include the trigger time, pulse width, dispersion measure (DM), Faraday rotation measure (RM), bandwidth, waiting time, peak flux and fluence. The distribution and time evolution of these parameters are investigated. Potential correlations between various parameter pairs are also extensively explored. The behaviors of different repeaters are then compared. It is found that the DM of FRB 20121102A seems to increase continuously on a long timescale. While the $DM$ of most repeaters varies in a narrow range of $\pm 3$ cm$^{-3}$ pc, FRB 20190520B is found to have a large variation range of $\pm 12$ cm$^{-3}$ pc. A linear correlation between $DM$ and the star formation rate is established. $RM$ evolves with time in a much more chaos behavior in different repeaters. Generally, the waiting time shows a bimodal distribution in each source. The implications of these features to the underlying physics are discussed.Comment: 47 pages, 51 figures, 8 table

How do tourists evaluate Chinese hotels at different cities? Mining online tourist reviewers for new insights

Affected by the factors like population, economic and geographic conditions, accommodation offerings are inherently different at different cities and characterized with their specific features. This heterogeneity is not limited to the supply-side but covers the demand-side as well. For instance, business and leisure tourists may favor different travel destinations. Therefore, the development of accommodation industry needs to match the evolving demands of tourists. In this study, we utilize text mining techniques to understand English-speaking tourists’ likes and dislikes with regard to hotels at different Chinese cities. Based on the studying the titles of 96,089 English reviews collected from TripAdvisor, the study seeks to explore the hotel attributes that tourists discussed in their reviews with regard to their lodging experience at a specific city. In particular, tourists’ complaints are studied through the use of low rating reviews. In addition, hotel features favored by tourists are identified via associating hotel attributes with sentiment-featured words like ‘great’ and ‘good’. Finally, an overall perspective on customer reviews is visualized in co-occurrence maps of jointly used sentiments and key-words. The research findings offer city-level strategic insights for hotel management

Synergism in Pharmacokinetics of Retagliptin and Metformin Observed during Clinical Trials of their Combination Therapy

Purpose: To investigate the safety and potential pharmacokinetic (PK) interaction between retagliptin, a selective inhibitor of dipeptidyl peptidase-4, and metformin in healthy subjects.Methods: In open-label, randomized, three-period, three-treatment crossover studies, 15 subjects received 100 mg retagliptin, 1500 mg metformin or the combination. The area under the curve from the time of dosing to infinity (AUCinf) and the maximum observed plasma concentration (Cmax) of each drug were measured.Results: The combination of retagliptin and metformin did not result in clinically significant alterations in the pharmacokinetics of SP2086 or metformin. The AUCinf and Cmax of retagliptin co-administered with metformin were 16.49 and 25.88 % higher than for retagliptin alone, respectively, while the AUCinf of metformin co-administered with retagliptin was 22.06 % higher than for metformin alone. The 90 % confidence interval of both glucose-lowering drugs’ AUCinf and Cmax of the geometric mean ratios of SP2086 + metformin fell within the pre-specified interval of 80 - 125 %. No laboratory adverse conditions occurred during the study. Retagliptin appeared generally safe and well-tolerated when administered alone or in combination with  metformin.Conclusion: The results may be an indication that no dose adjustments are likely to be required when retagliptin is given in combination with metformin

Feasibility study on posterior laminar screw fixation techniques in the axis

AbstractObjectiveTo get morphologic parameters of Chinese adults through observation and measurement on axial laminas, to evaluate the feasibility of placing axial laminar screws and to introduce the technique.MethodsRelative parameters of 28 sets of fresh Chinese adults' axial specimens, including distance from the superior and inferior entry points of axial laminar screws to the superior margins of axial laminas, superior, middle, inferior thickness and height of the axial laminas, length and angle of the axial laminar screw trajectories, distance from the entry points of axial laminar screws to the transverse foramen and central points of the inferior articular process, were measured with a digital caliper and a goniometer. Data were statistically analyzed.ResultsAveragely, distance from the superior and inferior entry points of axial laminar screws to the superior margins of axial laminas was 5 mm and 9 mm, superior, middle, inferior thickness and the height of the axial laminas were 3.2 mm, 6.7 mm, 5.5 mm and 12.8 mm respectively, and the length of the superior and inferior axial laminar screw trajectories was 26.2 mm and 25.5 mm, respectively.ConclusionsIt is feasible and reliable to apply posterior laminar screw fixation techniques to the axes of Chinese adults. Also the C2 laminar screw fixation technique can be taken as a supplementary to conventional posterior screw fixations of C2