Multi-angular polarimetric remote sensing to pinpoint global aerosol absorption and direct radiative forcing.

Quantitative estimations of atmospheric aerosol absorption are rather uncertain due to the lack of reliable information about the global distribution. Because the information about aerosol properties is commonly provided by single-viewing photometric satellite sensors that are not sensitive to aerosol absorption. Consequently, the uncertainty in aerosol radiative forcing remains one of the largest in the Assessment Reports of the Intergovernmental Panel on Climate Change (IPCC AR5 and AR6). Here, we use multi-angular polarimeters (MAP) to provide constraints on emission of absorbing aerosol species and estimate global aerosol absorption optical depth (AAOD) and its climate effect. Our estimate of modern-era mid-visible AAOD is 0.0070 that is higher than IPCC by a factor of 1.3-1.8. The black carbon instantaneous direct radiative forcing (BC DRF) is +0.33 W/m2 [+0.17, +0.54]. The MAP constraint narrows the 95% confidence interval of BC DRF by a factor of 2 and boosts confidence in its spatial distribution.

Case report of spongiotic gingivitis in an adult male treated with novel 9,300-nanometer carbon dioxide laser low-energy ablation.

BACKGROUND AND OVERVIEW: To date, only about 125 cases of juvenile or adult spongiotic gingivitis have been described in the literature, primarily from retrospective biopsy searches. Spongiotic gingivitis is a relatively new, often misdiagnosed, periodontal pathology that was originally attributed only to juveniles. This is the first case report to our knowledge on spongiotic gingivitis diagnosed in a middle-aged adult man and treated with a novel carbon dioxide (CO2) laser low-energy ablation therapy. CASE DESCRIPTION: A 56-year-old man sought treatment for a localized erythematous lesion on the facial gingiva of the maxillary left central incisor (tooth no. 9). Initial treatment was conventional excisional surgery and biopsy. Diagnosed as spongiotic gingivitis, it reoccurred in the same location within 4 months. It was then treated in 3 sessions using a novel 9,300-nm CO2 laser low-energy ablation set at 0.4 W and 1.25-mm cut width for an irradiance of 33.3 W/cm2 and energy density of 0.21 J/cm2. The lesion was significantly reduced and has shown no hyperplastic reoccurrence to date. CONCLUSIONS AND PRACTICAL IMPLICATIONS: This case report brings to dental professionals' attention that acute spongiotic gingivitis may occur in older adults, not just juveniles. As such, spongiotic gingivitis may be underreported in adults with localized gingivitis, possibly attributed to toothpastes containing sodium laurel sulfate. 9,300-nm CO2 laser therapy may successfully treat lesions such as acute spongiotic gingivitis without the need for anesthesia or additional medications. This report may also encourage further research on treatment modalities, biopsy of lesions resembling this entity, and improved reporting of adult spongiotic gingivitis to better understand this unique gingival pathology.

Beyond the Ångström Exponent: Probing Additional Information in Spectral Curvature and Variability of In Situ Aerosol Hyperspectral (0.3-0.7 µm) Optical Properties.

Ångström exponents (α) allow reconstruction of aerosol optical spectra over a broad range of wavelengths from measurements at two or more wavelengths. Hyperspectral measurements of atmospheric aerosols provide opportunities to probe measured spectra for information inaccessible from only a few wavelengths. Four sets of hyperspectral in situ aerosol optical coefficients (aerosol-phase total extinction, σ ext, and absorption, σ abs; liquid-phase soluble absorption from methanol, σ MeOH-abs, and water, σ DI-abs, extracts) were measured from biomass burning aerosols (BBAs). Hyperspectral single scattering albedo (ω), calculated from σ ext and σ abs, provide spectral resolution over a wide spectral range rare for this optical parameter. Observed spectral shifts between σ abs and σ MeOH-abs/σ DI-abs argue in favor of measuring σ abs rather than reconstructing it from liquid extracts. Logarithmically transformed spectra exhibited curvature better fit by second-order polynomials than linear α. Mapping second order fit coefficients (a 1, a 2) revealed samples from a given fire tended to cluster together, that is, aerosol spectra from a given fire were similar to each other and somewhat distinct from others. Separation in (a 1, a 2) space for spectra with the same α suggest additional information in second-order parameterization absent from the linear fit. Spectral features found in the fit residuals indicate more information in the measured spectra than captured by the fits. Above-detection σ MeOH-abs at 0.7 µm suggests assuming all absorption at long visible wavelengths is BC to partition absorption between BC and brown carbon (BrC) overestimates BC and underestimates BrC across the spectral range. Hyperspectral measurements may eventually discriminate BBA among fires in different ecosystems under variable conditions.

Active remote sensing of atmospheric dust using relationships between their depolarization ratios and reflectivity.

The backscattered light from agglomerated debris particles shows that an approximate linear correlation exists between the logarithm of the geometric albedo $ \log(A )$ of polydispersions of agglomerated debris particles and their lidar linear or circular depolarization ratios, $ \unicode{x00B5}_L$ and $ \unicode{x00B5}_C$. The nature of the relationship depends on the complex refractive index of the particles in the distribution. This extension of the Umov law can be used for lidar and radar characterizations by placing constraints on the reflectivity of the particles. It suggests that an approximate inverse relationship exists between the lidar ratio and the lidar depolarization ratios whose scaling parameter depends on the refractive index of the aerosol population.

Dental Faculty, Student, and Alumni Perceptions of Happiness and Life Satisfaction in Dental School: Foundations for Resilience and Well-Being.

This study examined happiness and satisfaction as possible foundations for long-term well-being and resilience in dental education. Psychological research has found that respect, camaraderie, and trust help define well-being and that resilience is built with these supportive influences. The aims of this study were to assess if happiness and life satisfaction reported by one U.S. dental school's faculty, students, and alumni also enhanced their perceived well-being and resilience and to determine the factor that most affected the participants' happiness. Email and hard copy surveys were distributed in 2018 and 2019 to all 71 full-time preclinical and clinical faculty members, 572 students in all four years, and 143 alumni who graduated in 2018 (total N = 786). Overall, 471 responded; response rates by group were as follows: faculty 87.3% (N = 62), students 65.9% (N = 377), and graduates 22.4% (N = 32). Of the three groups, responding faculty members reported having the highest levels of happiness in life (92.0%) and job satisfaction (90.3%). In the highest percentage reported, 90.2% of D4 students reported that the level of trust and respect they received from clinical faculty members contributed most to their happiness. The lowest level of happiness among the groups (71.0%) was reported by the D2 students. These results suggested that perceived well-being translated to happiness among the participants in our study. More research is needed to understand the relationship among positive environments, well-being, and provider resilience in dental education.

Spatial Representativeness Error in the Ground-Level Observation Networks for Black Carbon Radiation Absorption.

There is high uncertainty in the direct radiative forcing of black carbon (BC), an aerosol that strongly absorbs solar radiation. The observation-constrained estimate, which is several times larger than the bottom-up estimate, is influenced by the spatial representativeness error due to the mesoscale inhomogeneity of the aerosol fields and the relatively low resolution of global chemistry-transport models. Here we evaluated the spatial representativeness error for two widely used observational networks (AErosol RObotic NETwork and Global Atmosphere Watch) by downscaling the geospatial grid in a global model of BC aerosol absorption optical depth to 0.1° × 0.1°. Comparing the models at a spatial resolution of 2° × 2° with BC aerosol absorption at AErosol RObotic NETwork sites (which are commonly located near emission hot spots) tends to cause a global spatial representativeness error of 30%, as a positive bias for the current top-down estimate of global BC direct radiative forcing. By contrast, the global spatial representativeness error will be 7% for the Global Atmosphere Watch network, because the sites are located in such a way that there are almost an equal number of sites with positive or negative representativeness error.

Aerosol Absorption: Progress Towards Global and Regional Constraints.

PURPOSE OF REVIEW: Some aerosols absorb solar radiation, altering cloud properties, atmospheric stability and circulation dynamics, and the water cycle. Here we review recent progress towards global and regional constraints on aerosol absorption from observations and modeling, considering physical properties and combined approaches crucial for understanding the total (natural and anthropogenic) influences of aerosols on the climate. RECENT FINDINGS: We emphasize developments in black carbon absorption alteration due to coating and ageing, brown carbon characterization, dust composition, absorbing aerosol above cloud, source modeling and size distributions, and validation of high-resolution modeling against a range of observations. SUMMARY: Both observations and modeling of total aerosol absorption, absorbing aerosol optical depths and single scattering albedo, as well as the vertical distribution of atmospheric absorption, still suffer from uncertainties and unknowns significant for climate applications. We offer a roadmap of developments needed to bring the field substantially forward.

Effect of a Pilot Preclinical Incentive Program on Dental Students' Performance on a Clinical Competency Exam.

The aim of this study was to investigate the effect of a pilot preclinical incentive program on dental students' performance on a clinical competency (mock board) exam at Midwestern University College of Dental Medicine-Arizona. To assess the effect of preclinical grade incentives in a program called SUCCEED, scores from a clinical competency exam administered during the fall quarter of the fourth year were compared between the graduating classes of 2014 and 2015 (pre-SUCCEED curriculum) and the graduating class of 2016 (post-SUCCEED curriculum). The study hypothesized that the class participating in the SUCCEED program, with its incentives for greater preclinical preparation and practice, would score higher than the other classes on the exams. The results showed that the endodontics and periodontics pass rates and test scores from the Class of 2016 were higher than those from the Classes of 2014 and 2015; the prosthodontics pass rates were similar; and the operative dentistry pass rates and test scores were lower than the Classes of 2014 and 2015. While the results of two of the four subsections of the competency exam showed an improvement in clinical performance for the Class of 2016, the operative dentistry test scores for that class were less than expected. Based on the increased number of operative dentistry procedures performed in preclinical simulation and the clinic, the authors conclude that the competency exam should not be the only measure to evaluate success of the SUCCEED program.

Advanced characterisation of aerosol size properties from measurements of spectral optical depth using the GRASP algorithm.

This study evaluates the potential of using aerosol optical depth (τ a) measurements to characterise the microphysical and optical properties of atmospheric aerosols. With this aim, we used the recently developed GRASP (Generalized Retrieval of Aerosol and Surface Properties) code for numerical testing of six different aerosol models with different aerosol loads. The direct numerical simulations (self-consistency tests) indicate that the GRASP-AOD retrieval provides modal aerosol optical depths (fine and coarse) to within 0.01 of the input values. The retrieval of the fine-mode radius, width and volume concentration are stable and precise if the real part of the refractive index is known. The coarse-mode properties are less accurate, but they are significantly improved when additional a priori information is available. The tests with random simulated errors show that the uncertainty in the bimodal log-normal size distribution parameters increases as the aerosol load decreases. Similarly, the reduction in the spectral range diminishes the stability of the retrieved parameters. In addition to these numerical studies, we used optical depth observations at eight AERONET locations to validate our results with the standard AERONET inversion products. We found that bimodal log-normal size distributions serve as useful input assumptions, especially when the measurements have inadequate spectral coverage and/or limited accuracy, such as moon photometry. Comparisons of the mode median radii between GRASP-AOD and AERONET indicate average differences of 0.013 µm for the fine mode and typical values of 0.2-0.3 µm for the coarse mode. The dominant mode (i.e. fine or coarse) indicates a 10 % difference in mode radii between the GRASP-AOD and AERONET inversions, and the average of the difference in volume concentration is around 17 % for both modes. The retrieved values of the fine-mode τ a(500) using GRASP-AOD are generally between those values obtained by the standard AERONET inversion and the values obtained by the AERONET spectral deconvolution algorithm (SDA), with differences typically lower than 0.02 between GRASP-AOD and both algorithms. Finally, we present some examples of application of GRASP-AOD inversion using moon photometry and the airborne PLASMA sun photometer during the ChArMEx summer 2013 campaign in the western Mediterranean.

Retrievals of aerosol optical and microphysical properties from Imaging Polar Nephelometer scattering measurements.

A method for the retrieval of aerosol optical and microphysical properties from in situ light-scattering measurements is presented and the results are compared with existing measurement techniques. The Generalized Retrieval of Aerosol and Surface Properties (GRASP) is applied to airborne and laboratory measurements made by a novel polar nephelometer. This instrument, the Polarized Imaging Nephelometer (PI-Neph), is capable of making high-accuracy field measurements of phase function and degree of linear polarization, at three visible wavelengths, over a wide angular range of 3 to 177°. The resulting retrieval produces particle size distributions (PSDs) that agree, within experimental error, with measurements made by commercial optical particle counters (OPCs). Additionally, the retrieved real part of the refractive index is generally found to be within the predicted error of 0.02 from the expected values for three species of humidified salt particles, with a refractive index that is well established. The airborne measurements used in this work were made aboard the NASA DC-8 aircraft during the Studies of Emissions and Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys (SEAC4RS) field campaign, and the inversion of this data represents the first aerosol retrievals of airborne polar nephelometer data. The results provide confidence in the real refractive index product, as well as in the retrieval's ability to accurately determine PSD, without assumptions about refractive index that are required by the majority of OPCs.

Correlation Between Students' Dental Admission Test Scores and Performance on a Dental School's Competency Exam.

The aim of this study was to investigate whether there was a statistically significant positive correlation between dental students' Dental Admission Test (DAT) scores, particularly on the Perceptual Ability Test (PAT), and their performance on a dental school's competency exam. Scores from the written and clinical competency exam administered in the fall quarter of the fourth year of the curriculum at Midwestern University College of Dental Medicine-Arizona were compared to DAT scores of all 216 members of the graduating classes of 2012 and 2013. It was hypothesized that students who performed highly on one or more sections of the DAT would perform highly on the competency exam. Backward stepwise regression analyses were used to analyze the data. The results showed that the PAT scores were most strongly correlated with the competency exam scores and were a positive predictor for all three clinical sections of the exam (operative dentistry, periodontics, and endodontics). Positive predictors for the written portion of the exam were total DAT score for patient assessment and treatment planning and the DAT reading comprehension score for prosthodontics; there were no predictors for periodontics. The total variance explained by the results ranged from 4% to 15%. While statistically significant relationships were found between the students' PAT scores and clinical performance, DAT scores explained relatively little variance in the competency exam scores. According to these findings, neither the PAT nor any of the DAT components contributed to predicting these students' clinical performance.