Oxidation-reduction imaging of myoglobin reveals two-phase oxidation in the reperfused myocardium.

Myocardial infarction (MI) is a serious acute cardiovascular syndrome that causes myocardial injury due to blood flow obstruction to a specific myocardial area. Under ischemic-reperfusion settings, a burst of reactive oxygen species is generated, leading to redox imbalance that could be attributed to several molecules, including myoglobin. Myoglobin is dynamic and exhibits various oxidation-reduction states that have been an early subject of attention in the food industry, specifically for meat consumers. However, rarely if ever have the myoglobin optical properties been used to measure the severity of MI. In the current study, we develop a novel imaging pipeline that integrates tissue clearing, confocal and light sheet fluorescence microscopy, combined with imaging analysis, and processing tools to investigate and characterize the oxidation-reduction states of myoglobin in the ischemic area of the cleared myocardium post-MI. Using spectral imaging, we have characterized the endogenous fluorescence of the myocardium and demonstrated that it is partly composed by fluorescence of myoglobin. Under ischemia-reperfusion experimental settings, we report that the infarcted myocardium spectral signature is similar to that of oxidized myoglobin signal that peaks 3 h post-reperfusion and decreases with cardioprotection. The infarct size assessed by oxidation-reduction imaging at 3 h post-reperfusion was correlated to the one estimated with late gadolinium enhancement MRI at 24 h post-reperfusion. In conclusion, this original work suggests that the redox state of myoglobin can be used as a promising imaging biomarker for characterizing and estimating the size of the MI during early phases of reperfusion.

Higher inflammatory proteins predict future depressive symptom severity among adolescents with lower emotional clarity.

BACKGROUND: A growing body of work has implicated inflammation in the pathogenesis of depression. As not all individuals with heightened levels of peripheral inflammation develop symptoms of depression, additional work is needed to identify other factors that catalyze the relationship between inflammation and depressive symptoms. Given that elevated levels of inflammatory activity can induce a variety of emotional changes, the present study examined whether emotional clarity, the trait-like ability to identify, discern, and express one's emotions, influences the strength of the association between inflammatory signaling and concurrent and prospective symptoms of depression. METHODS: Community adolescents (N=225, Mage = 16.63 years), drawn from a larger longitudinal project investigating sex and racial differences in depression onset, provided blood samples to determine peripheral levels of interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), and C-reactive protein (CRP) at a baseline visit, along with self-report measures of emotional clarity and depressive symptom severity. Depressive symptom severity was assessed again at a follow-up visit approximately 5-months after baseline. RESULTS: Hierarchical multiple regressions detected a significant interaction between inflammatory markers and emotional clarity on future depression severity, controlling for baseline depressive symptoms. Specifically, among adolescents with low levels of emotional clarity, higher IL-6, CRP levels, and inflammatory composite scores were significantly associated with greater future depression severity. CONCLUSIONS: These results indicate that low emotional clarity and high inflammatory signaling may jointly confer risk for prospective depressive symptom severity among adolescents. Therapeutic interventions that improve emotional clarity may reduce risk of depressive symptoms among adolescents with low-grade peripheral inflammation.

Breaking Biomphalaria black box by in situ revelation of fluorescent Schistosoma mansoni parasites.

Tissue clearing is an old-fashioned method developed in the 1900's and used to turn an opaque biological object into a 3D visualizable transparent structure. Developed and diversified over the last decade, this method is most of the time applied to mammals' tissues, and especially mouse and human tissues for cytological, histological and pathophysiological studies. Through autofluorescence, immunofluorescence, in situ hybridization, intercalating agents, fluorescent transfection markers or fluorescent particle uptake, optically cleared samples can be monitored to discover new biological structures and cellular interactions through 3D-visualization, which can be more challenging in some extend through classical histological methods. Most of the tissue clearing procedures have been developed for specific applications like endogenous fluorescence visualization, immunolabeling or for revealing specific organs. Thus, choosing the adapted protocol may be empirical for non-model species, especially for mollusks for which very little related literature is available. Herein, we suggest an effective optical tissue clearing procedure for the freshwater snail Biomphalaria glabrata, known as the intermediate host of the human parasite Schistosoma mansoni. This clearing procedure involves solvents with a minimal toxicity, preserves the endogenous fluorescence of labeled parasites inside snail tissues and is compatible with an immunolabeling procedure.

Relating referential clarity and phonetic clarity in infant-directed speech.

Psycholinguistic research on children's early language environments has revealed many potential challenges for language acquisition. One is that in many cases, referents of linguistic expressions are hard to identify without prior knowledge of the language. Likewise, the speech signal itself varies substantially in clarity, with some productions being very clear, and others being phonetically reduced, even to the point of uninterpretability. In this study, we sought to better characterize the language-learning environment of American English-learning toddlers by testing how well phonetic clarity and referential clarity align in infant-directed speech. Using an existing Human Simulation Paradigm (HSP) corpus with referential transparency measurements and adding new measures of phonetic clarity, we found that the phonetic clarity of words' first mentions significantly predicted referential clarity (how easy it was to guess the intended referent from visual information alone) at that moment. Thus, when parents' speech was especially clear, the referential semantics were also clearer. This suggests that young children could use the phonetics of speech to identify globally valuable instances that support better referential hypotheses, by homing in on clearer instances and filtering out less-clear ones. Such multimodal "gems" offer special opportunities for early word learning. RESEARCH HIGHLIGHTS: In parent-infant interaction, parents' referential intentions are sometimes clear and sometimes unclear; likewise, parents' pronunciation is sometimes clear and sometimes quite difficult to understand. We find that clearer referential instances go along with clearer phonetic instances, more so than expected by chance. Thus, there are globally valuable instances ("gems") from which children could learn about words' pronunciations and words' meanings at the same time. Homing in on clear phonetic instances and filtering out less-clear ones would help children identify these multimodal "gems" during word learning.

Maintaining the working state of firefighters by utilizing self-concept clarity as a resource.

The working state of firefighters is important for their own safety as well as that of the general public. The purpose of this study is to investigate the correlations between self-concept clarity, resilience, work engagement, and job burnout among firefighters, as well as the impacts of self-concept clarity and resilience as resources that can maintain their working state. Based on data from 2,156 firefighters, analysis showed that self-concept clarity was negatively associated with job burnout and positively associated with work engagement. The results also showed that self-concept clarity had a direct effect on job burnout and work engagement, and an indirect effect by improving the firefighters' resilience. Maintaining and improving their self-concept clarity and resilience promises to be an effective strategy for guaranteeing the working state of firefighters.

Daily associations between global self-esteem and self-concept clarity and their relationships with subjective well-being in a sample of adult workers.

OBJECTIVES: The present pre-registered study examined the reciprocal day-to-day associations between global self-esteem and self-concept clarity and their incremental validity with respect to daily life satisfaction, positive affect, and negative affect. METHODS: We used intensive longitudinal data from 153 adult workers (45.1% women), over a period of 31 days. Data were analyzed using dynamic structural equation modeling. RESULTS: Results attested higher global self-esteem and self-concept clarity mean levels for older vs. younger participants, and lower global self-esteem and self-concept clarity variability for older vs. younger participants. Furthermore, global self-esteem and self-concept clarity were correlated at a cross-sectional daily level, yet only self-concept clarity states positively predicted subsequent global self-esteem states, while global self-esteem states did not predict subsequent self-concept clarity states. Daily global self-esteem and daily self-concept clarity further predicted subsequent daily higher life satisfaction and positive affect, respectively. CONCLUSION: Overall, our findings shed light on the short-term relationships linking global self-esteem and self-concept clarity, pointing to their discriminant validity in predicting individuals' subjective well-being.

Longitudinal relationships among sociocultural pressure for body image, self-concept clarity, and emotional well-being in adolescents.

INTRODUCTION: This study examined the longitudinal relationships among sociocultural pressure for body image (SPBI), self-concept clarity (SCC), and emotional well-being (EWB) at both the between- and within-person levels. METHODS: The participants were 2001 Chinese adolescents (age range 11-24, 42.9% males). Recruitment of participants occurred for 1 year across three waves (i.e., 6 months apart across three cohorts). The baseline and follow-up questionnaire surveys were utilized to assess SPBI, SCC, EWB, and background variables. Longitudinal associations between the above main variables were tested using a cross-lagged panel model (CLPM) and multilevel regression analysis. RESULTS: The CLPM and multilevel-model analysis showed that SCC longitudinally mediated the relationships between SPBI and EWB. Besides, gender and age were considered moderators in the associations among SPBI, SCC, and EWB. CONCLUSIONS: SCC could be an underlying mechanism for the longitudinal relationship between SPBI and EWB among Chinese adolescents, which provides a potential intervention target for improving adolescents' well-being from a sociocultural framework.

CLARITY increases sensitivity and specificity of fluorescence immunostaining in long-term archived human brain tissue.

BACKGROUND: Post mortem human brain tissue is an essential resource to study cell types, connectivity as well as subcellular structures down to the molecular setup of the central nervous system especially with respect to the plethora of brain diseases. A key method is immunostaining with fluorescent dyes, which allows high-resolution imaging in three dimensions of multiple structures simultaneously. Although there are large collections of formalin-fixed brains, research is often limited because several conditions arise that complicate the use of human brain tissue for high-resolution fluorescence microscopy. RESULTS: In this study, we developed a clearing approach for immunofluorescence-based analysis of perfusion- and immersion-fixed post mortem human brain tissue, termed human Clear Lipid-exchanged Acrylamide-hybridized Rigid Imaging / Immunostaining / In situ hybridization-compatible Tissue-hYdrogel (hCLARITY). hCLARITY is optimized for specificity by reducing off-target labeling and yields very sensitive stainings in human brain sections allowing for super-resolution microscopy with unprecedented imaging of pre- and postsynaptic compartments. Moreover, hallmarks of Alzheimer's disease were preserved with hCLARITY, and importantly classical 3,3'-diaminobenzidine (DAB) or Nissl stainings are compatible with this protocol. hCLARITY is very versatile as demonstrated by the use of more than 30 well performing antibodies and allows for de- and subsequent re-staining of the same tissue section, which is important for multi-labeling approaches, e.g., in super-resolution microscopy. CONCLUSIONS: Taken together, hCLARITY enables research of the human brain with high sensitivity and down to sub-diffraction resolution. It therefore has enormous potential for the investigation of local morphological changes, e.g., in neurodegenerative diseases.

Satellite imagery as a management tool for monitoring water clarity across freshwater ponds on Cape Cod, Massachusetts.

Water clarity serves as both an indicator and a regulator of biological function in aquatic systems. Large-scale, consistent water clarity monitoring is needed for informed decision-making. Inland freshwater ponds and lakes across Cape Cod, a 100-km peninsula in Massachusetts, are of particular interest for water clarity monitoring. Secchi disk depth (SDD), a common measure of water clarity, has been measured intermittently for over 200 Cape Cod ponds since 2001. Field-measured SDD data were used to estimate SDD from satellite data, leveraging the NASA/USGS Landsat Program and Copernicus Sentinel-2 mission, spanning 1984 to 2022. Random forest machine learning models were generated to estimate SDD from satellite reflectance data and maximum pond depth. Spearman rank correlations (rs) were "strong" for Landsat 5 and 7 (rs = 0.78 and 0.79), and "very strong" for Landsat 8, 9, and Sentinel-2 (rs = 0.83, 0.86, and 0.80). Mean absolute error also indicated strong predictive capacity, ranging from 0.65 to 1.05 m, while average bias ranged from -0.20 to 0.06 m. Long- and recent short-term changes in satellite-estimated SDD were assessed for 193 ponds, selected based on surface area and the availability of maximum pond depth data. Long-term changes between 1984 and 2022 established a retrospective baseline using the Mann-Kendall test for trend and Theil-Sen slope. Generally, long-term water clarity improved across the Cape; 149 ponds indicated increasing water clarity, and 8 indicated deteriorating water clarity. Recent short-term changes between 2021 and 2022 identified ponds that may benefit from targeted management efforts using the Mann-Whitney U test. Between 2021 and 2022, 96 ponds indicated deteriorations in water clarity, and no ponds improved in water clarity. While the 193 ponds analyzed here constitute only one quarter of Cape Cod ponds, they represent 85% of its freshwater surface area, providing the most spatially and temporally comprehensive assessment of Cape Cod ponds to date. Efforts are focused on Cape Cod, but can be applied to other areas given the availability of local field data. This study defines a framework for monitoring and assessing change in satellite-estimated SDD, which is important for both local and regional management and resource prioritization.

Cost-effectiveness of erosion mitigation to meet water clarity targets in the Manawatu-Whanganui Region of New Zealand.

Soil erosion is a significant environmental issue worldwide. It affects water quality, biodiversity, and land productivity. New Zealand government agencies and regional councils work to mitigate soil erosion through policies, management programmes, and funding for soil conservation projects. Information about cost-effectiveness is crucial for planning, targeting, and implementing erosion mitigation to achieve improvements in sediment-related water quality. While there is a good understanding of the costs of erosion mitigation measures, there is a dearth of literature on their cost-effectiveness in reducing sediment loads and improving water quality at the catchment level. In this study, we estimate the cost-effectiveness of erosion mitigation measures in meeting visual water clarity targets. The analysis utilizes the spatially explicit SedNetNZ erosion process and sediment budget modelling in the Manawatu-Whanganui Region and region-specific mitigation costs. The erosion mitigation measures considered in the analysis include afforestation, bush retirement, riparian retirement, space-planted trees, and gully tree planting. We modelled two scenarios with on-farm erosion mitigation implemented across the region from 2021 to 2100, resulting in a 48% and 60% reduction of total sediment load. We estimate the marginal costs to achieve the visual national bottom line for water clarity, as assessed by the length of waterways that meet the clarity targets. We also estimate the marginal costs of improving average water clarity, which can be linked with non-market valuation studies when conducting a cost-benefit analysis. We find that gully tree planting and space-planted trees are the most cost-effective mitigation measures and that riparian retirement is the least cost-effective. Moreover, cost-effectiveness is highly dependent on current land use and the biophysical features of the landscape. Our estimates can be used in cost-benefit analysis to plan and prioritize soil erosion mitigation at the catchment and regional levels.

AI-based Cleft Lip and Palate Surgical Information is Preferred by Both Plastic Surgeons and Patients in a Blind Comparison.

INTRODUCTION: The application of artificial intelligence (AI) in healthcare has expanded in recent years, and these tools such as ChatGPT to generate patient-facing information have garnered particular interest. Online cleft lip and palate (CL/P) surgical information supplied by academic/professional (A/P) sources was therefore evaluated against ChatGPT regarding accuracy, comprehensiveness, and clarity. METHODS: 11 plastic and reconstructive surgeons and 29 non-medical individuals blindly compared responses written by ChatGPT or A/P sources to 30 frequently asked CL/P surgery questions. Surgeons indicated preference, determined accuracy, and scored comprehensiveness and clarity. Non-medical individuals indicated preference. Calculations of readability scores were determined using seven readability formulas. Statistical analysis of CL/P surgical online information was performed using paired t-tests. RESULTS: Surgeons, 60.88% of the time, blindly preferred material generated by ChatGPT over A/P sources. Additionally, surgeons consistently indicated that ChatGPT-generated material was more comprehensive and had greater clarity. No significant difference was found between ChatGPT and resources provided by professional organizations in terms of accuracy. Among individuals with no medical background, ChatGPT-generated materials were preferred 60.46% of the time. For materials from both ChatGPT and A/P sources, readability scores surpassed advised levels for patient proficiency across seven readability formulas. CONCLUSION: As the prominence of ChatGPT-based language tools rises in the healthcare space, potential applications of the tools should be assessed by experts against existing high-quality sources. Our results indicate that ChatGPT is capable of producing high-quality material in terms of accuracy, comprehensiveness, and clarity preferred by both plastic surgeons and individuals with no medical background.

The Reciprocal Relations between Parental Psychological Control and Social Anxiety and the Mediating Role of Self-Concept Clarity Among Chinese Early Adolescents.

Although parental psychological control has been well-documented as a significant predictor of social anxiety among adolescents, few studies examine how changes in parental psychological control and adolescent social anxiety are reciprocally related at the within-person level, especially in Chinese culture. This longitudinal study examined reciprocal relations between parental psychological control and social anxiety, and the potential mediating role of self-concept clarity, by disentangling between- and within-person effects. A total of 4731 students (44.9% girls; Mage = 10.91 years, SD = 0.72) participated in a four-wave longitudinal study with 6-month intervals. Results from random intercept cross-lagged panel modeling indicated that parental psychological control directly predicted social anxiety, and vice versa. Parental psychological control indirectly predicted social anxiety via self-concept clarity, and social anxiety also indirectly predicted parental psychological control via self-concept clarity. These findings reveal a vicious cycle of mutual influence between parental psychological control and adolescent social anxiety in Chinese youth, and highlight the crucial role of self-concept clarity in the interplay between parenting and adolescent social functioning.

Online Self-Disclosure and Self-Concept Clarity Among Chinese Middle School Students: A Longitudinal Study.

The relationship between online self-disclosure and self-concept clarity has been previously examined through cross-sectional studies. This study examined causal connections between online self-disclosure and self-concept clarity among Chinese middle school students using longitudinal data collected over 18 months. Participants were 535 seventh-grade students aged 12-14 years (Mage = 12.93, SD = 0.54, 43.18% girls), assessed four times, six months apart. In a random intercept cross-lagged panel model, self-concept clarity significantly predicted online self-disclosure. Latent growth mixture modeling identified two distinct growth trajectories for both online self-disclosure (Rapid change, 7%; Slow change, 93%) and self-concept clarity (Rapid change, 8%; No change, 92%). Multiple logistic regression analysis suggested that changes in self-concept clarity influenced the developmental trajectory profile of online self-disclosure. Although male and female students differed in online self-disclosure and self-concept clarity, gender differences in the developmental trajectory profiles of online self-disclosure and self-concept clarity were not significant. Supporting adolescents in developing a clear self-concept to mitigate risks associated with excessive online self-disclosure is important.

Measurement reactivity in ambulatory assessment: Increase in emotional clarity over time independent of sampling frequency.

Ambulatory assessment (AA) studies are frequently used to study emotions, cognitions, and behavior in daily life. But does the measurement itself produce reactivity, that is, are the constructs that are measured influenced by participation? We investigated individual differences in intraindividual change in momentary emotional clarity and momentary pleasant-unpleasant mood over the course of an AA study. Specifically, we experimentally manipulated sampling frequency and hypothesized that the intraindividual change over time would be stronger when sampling frequency was high (vs. low). Moreover, we assumed that individual differences in dispositional mood regulation would moderate the direction of intraindividual change in momentary pleasant-unpleasant mood over time. Students (n = 313) were prompted either three or nine times a day for 1 week (data collection took place in 2019 and 2020). Multilevel growth curve models showed that momentary emotional clarity increased within participants over the course of the AA phase, but this increase did not differ between the two sampling frequency groups. Pleasant-unpleasant mood did not show a systematic trend over the course of the study, and mood regulation did not predict individual differences in mood change over time. Again, results were not moderated by the sampling frequency group. We discuss limitations of our study (e.g., WEIRD sample) and potential practical implications regarding sampling frequency in AA studies. Future studies should further systematically investigate the circumstances under which measurement reactivity is more likely to occur.

Using benefit transfer to estimate housing value increases from improved water clarity: A case study of lakes in Kosciusko County, Indiana.

This study provides step-by-step guidance for practitioners and local stakeholders on how to use existing study results to conduct benefit transfer (BT), and ultimately make informed predictions of how improvements in lake water clarity may benefit surrounding communities. The procedures are demonstrated using a publicly available meta-dataset developed by the United States Environmental Protection Agency, and a subsequent meta-analysis that synthesizes the literature on how improvements in water clarity impact home values. The BT procedures are demonstrated using a case study of 14 large lakes in Kosciusko County, Indiana. Lake-specific average increases in home values, as well as the value of the housing stock in aggregate, are calculated for illustrative improvements in lake water clarity. This analysis provides a critical bridge to better connect high-quality, academic research with real-world policy analysis, and ultimately serves to better equip local governments and stakeholders to make more informed policy and land use decisions.

Insulative Biobased Glaze from Wood Laminates Obtained by Self-Adhesion.

The combination of optical transparency and mechanical strength is a highly desirable attribute of wood-based glazing materials. However, such properties are typically obtained by impregnation of the highly anisotropic wood with index-matching fossil-based polymers. In addition, the presence of hydrophilic cellulose leads to a limited water resistance. Herein, this work reports on an adhesive-free lamination that uses oxidation and densification to produce transparent all-biobased glazes. The latter are produced from multilayered structures, free of adhesives or filling polymers, simultaneously displaying high optical clarity and mechanical strength, in both dry and wet conditions. Specifically, high values of optical transmittance (≈85.4%), clarity (≈20% with low haze) at a thickness of ≈0.3 mm, and highly isotropic mechanical strength and water resistance (wet strength of ≈128.25 MPa) are obtained for insulative glazes exhibiting low thermal conductivity (0.27 W m-1 K-1 , almost four times lower than glass). The proposed strategy results in materials that are systematically tested, with the leading effects of self-adhesion induced by oxidation rationalized by ab initio molecular dynamics simulation. Overall, this work demonstrates wood-derived materials as promising solutions for energy-efficient and sustainable glazing applications.

Long-term follow-up of patients with relapsing multiple sclerosis from the CLARITY/CLARITY Extension cohort of CLASSIC-MS: An ambispective study.

BACKGROUND: CLASSIC-MS evaluated the long-term efficacy of cladribine tablets in patients with relapsing multiple sclerosis. OBJECTIVE: Report long-term mobility and disability beyond treatment courses received in CLARITY/CLARITY Extension. METHODS: This analysis represents CLASSIC-MS patients who participated in CLARITY with/without participation in CLARITY Extension, and received ⩾1 course of cladribine tablets or placebo (N = 435). Primary objective includes evaluation of long-term mobility (no wheelchair use in the 3 months prior to first visit in CLASSIC-MS and not bedridden at any time since last parent study dose (LPSD), i.e. Expanded Disability Status Scale (EDSS) score <7). Secondary objective includes long-term disability status (no use of an ambulatory device (EDSS < 6) at any time since LPSD). RESULTS: At CLASSIC-MS baseline, mean ± standard deviation EDSS score was 3.9 ± 2.1 and the median time since LPSD was 10.9 (range = 9.3-14.9) years. Cladribine tablets-exposed population: 90.6% (N = 394), including 160 patients who received a cumulative dose of 3.5 mg/kg over 2 years. Patients not using a wheelchair and not bedridden: exposed, 90.0%; unexposed, 77.8%. Patients with no use of an ambulatory device: exposed, 81.2%; unexposed, 75.6%. CONCLUSION: With a median 10.9 years' follow-up after CLARITY/CLARITY Extension, findings suggest the sustained long-term mobility and disability benefits of cladribine tablets.

Experiencing anxiety in breast cancer survival: Does perceived emotional intelligence matter?

BACKGROUND: The specialized literature shows that breast cancer (BC) survivors have a certain vulnerability to express anxiety about the changes that the disease entails in their lives. Breast cancer is a specific adverse circumstance, but women who have not experienced this disease may also be exposed to other anxiety-provoking life crises. In both cases, perceived emotional intelligence (PEI)-consisting of emotional attention (EA), emotional clarity (EC), and emotional repair (ER)-seems to impact on such emotional distress. OBJECTIVE: To identify the mechanism through which PEI may mediate the relationship between BC survivorship, compared to a controlled group, and anxiety. METHODS: 636 women were divided into two groups: 56 BC survivors and 580 healthy controls. The Hospital Anxiety and Depression Scale and the Trait Meta-Mood Scale were administered. RESULTS: BC survivors differed from the control group in showing lower levels of EA and higher levels of ER. The global mediation model showed an explanatory capacity of 27% on anxiety (p = 0.000). Four significant indirect effects were obtained: two acted as risk pathways and the other two as protective pathways. The strongest effect indicated an increase in anxiety in BC survivors due to the mediated effect of low EA and EC. CONCLUSIONS: Knowing the impact of PEI on anxiety on disease survival could be the empirical basis for developing interventions to improve psychological adjustment at the end of treatments.

Low-Cost Sensor Performance Intercomparison, Correction Factor Development, and 2+ Years of Ambient PM2.5 Monitoring in Accra, Ghana.

Particulate matter air pollution is a leading cause of global mortality, particularly in Asia and Africa. Addressing the high and wide-ranging air pollution levels requires ambient monitoring, but many low- and middle-income countries (LMICs) remain scarcely monitored. To address these data gaps, recent studies have utilized low-cost sensors. These sensors have varied performance, and little literature exists about sensor intercomparison in Africa. By colocating 2 QuantAQ Modulair-PM, 2 PurpleAir PA-II SD, and 16 Clarity Node-S Generation II monitors with a reference-grade Teledyne monitor in Accra, Ghana, we present the first intercomparisons of different brands of low-cost sensors in Africa, demonstrating that each type of low-cost sensor PM2.5 is strongly correlated with reference PM2.5, but biased high for ambient mixture of sources found in Accra. When compared to a reference monitor, the QuantAQ Modulair-PM has the lowest mean absolute error at 3.04 µg/m3, followed by PurpleAir PA-II (4.54 µg/m3) and Clarity Node-S (13.68 µg/m3). We also compare the usage of 4 statistical or machine learning models (Multiple Linear Regression, Random Forest, Gaussian Mixture Regression, and XGBoost) to correct low-cost sensors data, and find that XGBoost performs the best in testing (R2: 0.97, 0.94, 0.96; mean absolute error: 0.56, 0.80, and 0.68 µg/m3 for PurpleAir PA-II, Clarity Node-S, and Modulair-PM, respectively), but tree-based models do not perform well when correcting data outside the range of the colocation training. Therefore, we used Gaussian Mixture Regression to correct data from the network of 17 Clarity Node-S monitors deployed around Accra, Ghana, from 2018 to 2021. We find that the network daily average PM2.5 concentration in Accra is 23.4 µg/m3, which is 1.6 times the World Health Organization Daily PM2.5 guideline of 15 µg/m3. While this level is lower than those seen in some larger African cities (such as Kinshasa, Democratic Republic of the Congo), mitigation strategies should be developed soon to prevent further impairment to air quality as Accra, and Ghana as a whole, rapidly grow.

Absolute quantification of SARS-CoV-2 with Clarity Plus™ digital PCR.

In recent years, the usage of digital polymerase chain reaction (dPCR) for various clinical applications has increased exponentially. In this study, a dPCR assay optimized on the Clarity Plus™ dPCR system was evaluated for the absolute quantification of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of the global coronavirus disease 2019 (COVID-19) outbreak. The assay demonstrated good inter- and intra- assay precision, accuracy, as well as excellent linearity across a range of over 6 orders of magnitude for target gene quantification. In addition, a comparison of the assay on both dPCR and qPCR platforms revealed that dPCR exhibited a slightly higher sensitivity compared to its qPCR counterpart when quantifying SARS-CoV-2 at a lower concentration. Overall, the results showed that the dPCR assay is a reliable and effective approach for the absolute quantification of SARS-CoV-2 and can be a valuable molecular tool in clinical applications such as detecting low viral loads in patients as well as in wastewater surveillance of COVID-19.