108 research outputs found

    Comparison between the Temperature Measurements by TIMED/SABER and Lidar in the Mid-Latitude

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    Comparisons of monthly-mean nighttime temperature profiles observed by the Sodium Lidar at Colorado State University and TIMED/SABER over passes are made. In the altitude range from 85 km to about 100 km, the two observations are in excellent agreement. Though within each other s error bars, important differences occur below 85 km in the entire year and above 100 km in the summer season. Possible reasons for these difference are high photon noise below 85 km in lidar observations, and less than accurate assumptions in the concentration of important chemical species like oxygen (and its quenching rate) in the SABER retrieval above 100 km. However, the two techniques both show the two-level mesopause thermal structure, with the times of change from one level to the other in excellent agreement. Comparison indicates that the high-level (winter) mesopause altitudes are also in excellent agreement between the two observations, though some difference may exist in the low-level (summer) mesopause altitudes between ground-based and satellite-borne data

    Enamel remineralization via poly(amido amine) and adhesive resin containing calcium phosphate nanoparticles

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    Objectives:The objective of this study was to investigate enamel remineralization using salivary statherin pro-tein-inspired poly(amidoamine) dendrimer (SN15-PAMAM) and adhesive containing nanoparticles of amor-phous calcium phosphate (NACP) in a cyclic artificial saliva/demineralizing solution for thefirst time.Methods:The enamel shear bond strengths of NACP adhesives were measured compared to commercial adhesive(Scotchbond Multi-Purpose, 3 M). Adhesive disks containing NACP were tested for calcium (Ca) and phosphorus(P) ions release. Four groups were tested: (1) enamel control, (2) enamel with NACP, (3) enamel with SN15-PAMAM, and (4) enamel with SN15-PAMAM + NACP. The specimens were treated with cyclic artificial saliva/demineralizing solution for 28 days. The remineralized enamel specimens were examined by surface and cross-sectional hardness test.Results:NACP adhesive yielded a similar shear bond strength to commercial control (Scotchbond Multi-Purpose,3 M). NACP adhesive released high levels of Ca and P ions. At 28 days, the enamel hardness of SN15-PAMAM +NACP group was 2.89 ± 0.13 GPa, significantly higher than that of control group (1.46 ± 0.10 GPa) (p< 0.05).SN15-PAMAM + NACP increased the enamel cross-sectional hardness at 28 days; at 25Όm, enamel cross-sectional hardness was 90 % higher than that of control group (p< 0.05).Significance:The novel SN15-PAMAM + NACP adhesive method could achieve 90 % higher enamel reminer-alization of the artificial caries than the control under acid challenge for thefirst time. This method is promisingfor use after tooth cavity preparation, or as a coating on enamel with white spot lesions (WSLs) for prevention, toreduce secondary caries, prevent caries procession and protect tooth structures

    Mental Disorder Symptoms during the COVID-19 Pandemic in Latin America – A Systematic Review and Meta-analysis

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    Aims There is a lack of evidence related to the prevalence of mental health symptoms as well as their heterogeneities during the coronavirus disease 2019 (COVID-19) pandemic in Latin America, a large area spanning the equator. The current study aims to provide meta-analytical evidence on mental health symptoms during COVID-19 among frontline healthcare workers, general healthcare workers, the general population and university students in Latin America. Methods Bibliographical databases, such as PubMed, Embase, Web of Science, PsycINFO and medRxiv, were systematically searched to identify pertinent studies up to August 13, 2021. Two coders performed the screening using predefined eligibility criteria. Studies were assigned quality scores using the Mixed Methods Appraisal Tool. The double data extraction method was used to minimise data entry errors. Results A total of 62 studies with 196 950 participants in Latin America were identified. The pooled prevalence of anxiety, depression, distress and insomnia was 35%, 35%, 32% and 35%, respectively. There was a higher prevalence of mental health symptoms in South America compared to Central America (36% v. 28%, p \u3c 0.001), in countries speaking Portuguese (40%) v. Spanish (30%). The pooled prevalence of mental health symptoms in the general population, general healthcare workers, frontline healthcare workers and students in Latin America was 37%, 34%, 33% and 45%, respectively. Conclusions The high yet heterogenous level of prevalence of mental health symptoms emphasises the need for appropriate identification of psychological interventions in Latin America
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