Pure rotational Raman lidar for full-day troposphere temperature measurement at Zhongshan Station (69.37°S, 76.37°E), Antarctica.

A pure rotational Raman lidar (PRRL) for full-day troposphere temperature measurement was deployed in February 2020 at Zhongshan Station (69.37°S, 76.37°E), Antarctica, by the 36th Chinese National Antarctic Research Expedition. The PRRL emits a 532.23-nm laser light and employs a 203.2-mm telescope to collect atmospheric backscatter. Cubic nonpolarizing beam splitters are introduced to yield a compact optics arrangement. A quasi-single-line-extraction technique is proposed for extracting the molecular Stokes line signals. A lidar container with a window system is customized to house the whole PRRL system for long-term stable operation. An approach using a laser plummet is developed for fast and convenient adjustment of the telescope zenithward. A home-made calibration module is utilized for straightforward visual optics adjustment with ∼35.3-µrad angular positioning accuracy. Both typical daytime and nighttime temperature measurement examples are presented to verify the lidar performance. From a 30-h continuous temperature measurement result, it is found the tropopause is located at ∼10.8 km above ground level with a mean temperature of ∼203 K; significant temperature variability occurs only at the inversion areas, while off which the 1-h temperature profiles are relatively similar in form with an average lapse rate of -8.3 K/km.

Prognosis of Second Molars with External Root Resorption Caused by Adjacent Embedded Third Molars.

INTRODUCTION: This prospective study was designed to determine the prognosis of second molars with external root resorption (ERR-M2s) caused by embedded third molars (EM3s) following EM3 removal and explore related predictors. METHODS: This study consecutively enrolled 58 participants who had asymptomatic second molars with apical external root resorption caused by EM3s. EM3s were extracted, and follow-up examinations were conducted at 1 week, 4 weeks, and 6 months. The primary outcome was prognosis of ERR-M2s after third molar extraction without any further intervention, as assessed via clinical and radiographic examinations. Potential predictors (sex, age, number of roots, EM3s position, type and degree of external root resorption) of prognosis were analyzed via univariable and multivariable analyses. RESULTS: A total of 63 ERR-M2s from 58 patients (16 males and 42 females; 19-57 years of age) were evaluated. At the last follow-up, 56 teeth (89%) remained asymptomatic and normal response to heat and cold tests. According to univariable analyses, ERR-M2s were more likely to remain normal response to heat and cold tests in younger patients. In the multivariable analysis, older age (odds ratio, 1.118; 95% confidence interval, 1.026-1.219; P < .05) and the type of all roots affected (odds ratio, 0.073; 95% confidence interval, 0.007-0.754; P < .05) were significantly associated with poor prognosis. CONCLUSIONS: Asymptomatic ERR-M2s have a high probability of remaining normal pulp without further intervention after EM3 extraction, especially in younger patients. No intervention except follow-up and observation is necessary.

Role of Metformin in Morbidity and Mortality Associated with Urinary Tract Infections in Patients with Type 2 Diabetes.

We conducted this study to compare the morbidity and mortality associated with UTI and sepsis, between metformin users and nonusers in patients with diabetes. As such, 40,774 propensity score-matched metformin users and nonusers were identified from Taiwan's National Health Insurance Research Database, between 1 January 2000 and 31 December 2017. We adopted the Cox proportional hazards model with robust standard error estimates for comparing the risks of UTI, sepsis, and death due to UTI or sepsis, in patients with T2DM. Compared with the nonuse of metformin, the aHRs (95% CI) for metformin use in UTI, recurrent UTI, sepsis, and death due to UTI or sepsis were 1.06 (0.98, 1.15), 1.08 (0.97, 1.2), 1.01 (0.97, 1.06), and 0.58 (0.42, 0.8), respectively. The cumulative incidence of death due to UTI or sepsis was significantly lower in metformin users than in nonusers (p = 0.002). A longer cumulative duration of metformin use had a lower aHR in the risk of death due to UTI or sepsis than metformin nonuse. In patients with T2DM, metformin use showed no significant differences in the risks of UTI, recurrent UTI, or sepsis. However, it was associated with a lower risk of death due to UTI or sepsis than metformin nonuse.

Metformin and the Development of Asthma in Patients with Type 2 Diabetes.

We conducted this study to compare the risks of asthma development and exacerbation between metformin users and nonusers. Overall, 57,743 propensity score-matched metformin users and nonusers were identified from Taiwan's National Health Insurance Research Database between 1 January 2000, and 31 December 2017. We used the Cox proportional hazards model with robust standard error estimates to compare the risks of asthma onset, exacerbation, and hospitalization for asthma in participants with type 2 diabetes (T2D). Compared with metformin nonuse, the aHRs (95% CI) for metformin use in asthma development, exacerbation, and hospitalization for asthma were 1.13 (1.06−1.2), 1.62 (1.35−1.95), and 1.5 (1.22−1.85), respectively. The cumulative incidences of asthma development, exacerbation, and hospitalization for asthma were significantly higher in metformin users than nonusers (p < 0.001). A longer cumulative duration of metformin use for more than 728 days was associated with significantly higher risks of outcomes than metformin nonuse. Our study demonstrated that metformin users showed significantly higher risks of asthma development, exacerbation, and hospitalization for asthma than metformin nonusers. Moreover, metformin use for more than 728 days was associated with higher risks of outcomes. A randomized control study is warranted to verify our results.

[Clinical study of age-related sensory innervation of the anterior hard palate].

OBJECTIVES: The present study aimed to explore the innervation of the anterior hard palatine and its relationship with individual development stage. Specifically, the effects of anesthesia on patients of different ages were observed, and neurodevelopment in the maxillofacial region was invesitgated. References that are helpful in selecting local anesthesia were provided. METHODS: A total of 182 patients with mixed dentition were randomly divided into the nasopalatine nerve block and greater palatine nerve block groups. Then, 219 patients with permanent dentition were divided into an adolescent group (13-18 years old) and adult group (over 19 years old), all of whom underwent bilateral greater palatine nerve block. Palatal mucosal pain sensation was tested pre- and post-anesthesia with Von Frey hairs. RESULTS: Among the children with mixed dentition, bilateral greater palatine nerve block tended to result in better anesthetic effects than nasopalatine nerve block (P<0.05), except in the incisive papilla. No difference in anesthetic effect was observed between adolescents and adults (P>0.05). The bilateral greater palatine nerve block was more effective in inducing an anesthestic effect in the anterior hard palatine in mixed dentition than in permanent dentition (over 13 years old; P<0.05). CONCLUSIONS: The sensation of the anterior hard palatine seems mainly dominated by the greater palatine nerve until mixed dentition and gradually shifted to the nasopalatine nerve in conjunction with maxillary development and tooth replacement. Hence, the innervation of the anterior hard palatine induce a secondary development during the development of the maxilla.

[Prognosis of teeth with external root resorption caused by adjacent impacted teeth].

OBJECTIVE: This study aimed to investigate the prognosis of permanent teeth with external root resorption (ERR) caused by adjacent impacted teeth. METHODS: A total of 75 ERR teeth (permanent teeth) caused by adjacent impacted teeth of 63 patients were included. The prognosis of ERR teeth was analyzed followed by minimally invasive extraction of the adjacent impacted teeth. The time of follow-up was six months. The relationship between prognosis of ERR teeth and patients' age, gender, root number, type of root resorption and degree of root resorption were analyzed. RESULTS: In the 75 ERR teeth, 67 teeth (89.3%) did not show pulpitis symptoms. The clinical outcome was found to be related with age (r=0.330, P<0.05), whereas no relationships with gender, root number, as well as type and degree of root resorption were observed (P>0.05). Pulpitis symptom was not found in ERR teeth of patients under 30 years old. CONCLUSIONS: For ERR teeth caused by adjacent impacted teeth, keeping the pulp vital after surgical removal of impacted teeth is highly probable. Post-operative follow-up instead of preventive root canal therapy of ERR teeth is recommended.

[Research progress on the modification of guided bone regeneration membranes].

Guided bone regeneration (GBR) is an important technique to solve bone defect problems. In this technique, GBR barrier membranes play an irreplaceable role. GBR membranes can act as a barrier protecting fibroblasts from bone defects and promote osteoblast adhesion and proliferation, leading to bone regeneration. GBR barrier membranes should be enhanced because of the disadvantages of collagen membranes, which are extensively applied to the field of GBR. Therefore, various efforts have been devoted to modifying the antibacterial and osteogenic properties of GBR barrier membranes and developing novel materials. This article reviews the research advancements on the modification of GBR barrier membranes and discover future directions for the development of GBR barrier membranes to provide a reference for bone tissue engi-neering and repair.

[Relationship between initial archwire materials and pain at the initial stage of orthodontic treatment: a systematic review and network Meta-analysis].

OBJECTIVE: This review aims to assess the relationship between initial archwire materials and pain at the initial stage of orthodontic treatment. METHODS: On October 1, 2017, seven databases were searched electronically for studies oninitial archwire materials and pain at the initial stage of orthodontic treatment. Quality assessment was performed with bias risk assessment tools suggested by Cochrane's handbook. Data extraction of included studies was also carried out. Network Meta-
analysis was conducted using R 3.4.2 (with JAGS 4.3.0), GeMTC 0.14.3, and STATA 11.0. RESULTS: Five studies with 330 participants were included, comparing four different materials: multi-stranded stainless steel, conventional nickel-titanium, super-elastic nickel-titanium, and thermal heat-activated nickel-titanium. Two studies were at low risk of bias, one was at high risk of bias, and the remaining two were at unclear risk of bias. Network Meta-analysis results showed no statistical differences of pain among the four initial archwire materials at day 1 and day 7. However, the most painless material was most likely to be thermal heat-activated nickel-titanium on rank probability. CONCLUSIONS: On statistical probability, thermal heat-activated nickel-titanium initial arch wires is most likely to cause the least pain at the initial stage of orthodontic treatment, compared with other materials.

Fe Boltzmann temperature lidar: design, error analysis, and initial results at the north and south poles.

The design, development, and first measurements of a novel mesospheric temperature lidar are described. The lidar technique employs mesospheric Fe as a fluorescence tracer and relies on the temperature dependence of the population difference of two closely spaced Fe transitions. The principal advantage of this technique is that robust solid-state broadband laser source(s) can be used that enables the lidar to be deployed at remote locations and aboard research aircraft. We describe the system design and present a detailed analysis of the measurement errors. Correlative temperature observations, made with the Colorado State University Na lidar at Fort Collins, Colorado, are also discussed. Last, we present the initial range-resolved temperature measurements in the mesosphere and lower thermosphere over both the North and the South Poles obtained with this system.