Seasonal variation in the relationship between leaf chlorophyll content and photosynthetic capacity.

Accurate estimation of photosynthesis is crucial for ecosystem carbon cycle modelling. Previous studies have established an empirical relationship between photosynthetic capacity (maximum carboxylation rate, Vcmax; maximum electron transport rate, Jmax) and leaf chlorophyll (Chl) content to infer global photosynthetic capacity. However, the basis for the Chl-Vcmax relationship remains unclear, which is further evidenced by the temporal variations in the Chl-Vcmax relationship. Using multiple years of observations of four deciduous tree species, we found that Vcmax and Jmax acclimate to photosynthetically active radiation faster (4-8 weeks) than Chl (10-12 weeks). This mismatch in temporal scales causes seasonality in the Vcmax-Chl relationship. To account for the mismatch, we used a Chl fluorescence parameter (quantum yield of Photosystem II, Φ(II)) to tighten the relationship and found Φ(II) × Chl correlated with Vcmax and Jmax (r2 = 0.74 and 0.72 respectively) better than only Chl (r2 = 0.7 and 0.6 respectively). It indicates that Φ(II) accounts for the short-term adjustment of leaf photosynthetic capacity to light, which was not captured by Chl. Our study advances our understanding of the ecophysiological basis for the empirical Vcmax-Chl relationship and how to better infer Vcmax from Chl and fluorescence, which guides large-scale photosynthesis simulations using remote sensing.

China's Fossil Fuel CO2 Emissions Estimated Using Surface Observations of Coemitted NO2.

Accurate estimates of fossil fuel CO2 (FFCO2) emissions are of great importance for climate prediction and mitigation regulations but remain a significant challenge for accounting methods relying on economic statistics and emission factors. In this study, we employed a regional data assimilation framework to assimilate in situ NO2 observations, allowing us to combine observation-constrained NOx emissions coemitted with FFCO2 and grid-specific CO2-to-NOx emission ratios to infer the daily FFCO2 emissions over China. The estimated national total for 2016 was 11.4 PgCO2·yr-1, with an uncertainty (1σ) of 1.5 PgCO2·yr-1 that accounted for errors associated with atmospheric transport, inversion framework parameters, and CO2-to-NOx emission ratios. Our findings indicated that widely used "bottom-up" emission inventories generally ignore numerous activity level statistics of FFCO2 related to energy industries and power plants in western China, whereas the inventories are significantly overestimated in developed regions and key urban areas owing to exaggerated emission factors and inexact spatial disaggregation. The optimized FFCO2 estimate exhibited more distinct seasonality with a significant increase in emissions in winter. These findings advance our understanding of the spatiotemporal regime of FFCO2 emissions in China.

Relationship between pericoronary fat-attenuation values quantified by coronary computed tomography angiography and coronary artery disease severity.

AIM: To explore the relationship between pericoronary fat-attenuation index (FAI) values and coronary artery disease (CAD) severity measured using coronary computed tomography angiography (CCTA). MATERIALS AND METHODS: This study retrospectively included 428 patients with CAD who were eligible and underwent CCTA at our hospital. CAD severity on CCTA images including obstructive stenosis and extensive lesions, and segment stenosis and involvement score (SSS, SIS), and CAD-RADS classification were assessed. FAI values for left anterior descending (LAD), left circumflex (LCX) branches, and right coronary artery (RCA) were quantified using fully automated software. The relationship between FAI values and CAD severity was assessed using univariate and multivariate regression models. RESULTS: Univariate analyses showed that sex and current smoking were associated with elevated FAILAD and FAILCX values (all P<0.05), whereas CAD severity was not relevant (all P>0.05). Not only clinical factors such as sex, current smoking, and hypertension were associated with elevated FAIRCA, but also indicators to assess CAD severity including obstructive stenosis, SIS, and SSS were related to it (all P<0.05). Multivariate analysis demonstrated that after correcting for the effects of other conventional cardiovascular risk factors and CCTA imaging features, current smoking was an independent risk factor for elevated FAI values (odds ratio [OR] = 0.569, 0.458, and 0.517; all P<0.05), whereas that SSS (OR=1.041, P=0.027) for elevated FAIRCA values. CONCLUSION: Following correction for conventional cardiovascular risk factors and imaging characteristics, current smoking was an independent clinical risk factor for elevated FAI values, and SSS was an independent risk factor for elevated FAIRCA values.

Added value of spectral computed tomography quantitative parameters for differentiating tuberculosis-associated fibrosing mediastinitis from endobronchial lung cancer: initial results.

OBJECTIVE: The objective of this study was to explore the added value of spectral computed tomography (CT) parameters to conventional CT features for differentiating tuberculosis-associated fibrosing mediastinitis (TB-associated FM) from endobronchial lung cancer (EBLC). METHODS: Chest spectral CT enhancement images from 109 patients with atelectasis were analyzed retrospectively. These patients were divided into two distinct categories: the TB-associated FM group (n = 77) and the EBLC group (n = 32), based on bronchoscopy and/or pathological findings. The selection of spectrum parameters was optimized with the least absolute shrinkage and selection operator regression analysis. The relationship between the spectrum parameters and conventional parameters was explored using Pearson's correlation. Multivariate logistic regression analysis was used to build spectrum model. The spectrum parameters in the spectrum model were replaced with their corresponding conventional parameters to build the conventional model. Diagnostic performances were evaluated using receiver operating characteristic curve analyses. RESULTS: There was a moderate correlation between the parameters ㏒(L-AEFNIC) - ㏒(L-AEFC) (r= 0.419; p< 0.0001), ㏒(O-AEF40KeV) - ㏒(O-AEFC) (r= 0.475; p< 0.0001), [L-A-hydroxyapatite {HAP}(I)] - (L-U-CT) (r= 0.604; p< 0.0001), {arterial enhancement fraction (AEF) derived from normalized iodine concentration (NIC) of lymph node (L-AEFNIC), AEF derived from CT40KeV of bronchial obstruction (O-AEF40KeV), arterial-phase Hydroxyapatite (Iodine) concentration of lymph node [L-A-HAP(I)], AEF derived from conventional CT (AEFC), unenhanced CT value (U-CT)}. Spectrum model could improve diagnostic performances compared to conventional model (area under curve: 0.965 vs 0.916, p= 0.038). CONCLUSION: There was a moderate correlation between spectrum parameters and conventional parameters. Integrating conventional CT features with spectrum parameters could further improve the ability in differentiating TB-associated FM from EBLC.

Comparative assessment of leaf photosynthetic capacity datasets for estimating terrestrial gross primary productivity.

The maximum Rubisco carboxylation rate normalized to 25 °C (Vcmax25) is a key parameter in terrestrial biosphere models for simulating carbon cycling. Recently, global distributions of Vcmax25 have been derived through various methods and different data, including field measurements, ecological optimality theory (EOT), leaf chlorophyll content (LCC), and solar-induced chlorophyll fluorescence (SIF). However, direct validation poses challenges due to high uncertainty arising from limited ground-based observations. This study conducted an indirect evaluation of four Vcmax25 datasets by assessing the accuracy of gross primary productivity (GPP) simulated using the Biosphere-atmosphere Exchange Process Simulator (BEPS) at both site and global scales. Results indicate that, compared to utilizing Vcmax25 fixed by plant functional types (PFT) derived from field measurements, incorporating Vcmax25 derived from SIF and LCC (SIF + LCC), or solely LCC, into BEPS significantly reduces simulated errors in the annual total GPP, with a 23.2 %-25.1 % decrease in the average absolute bias across 196 FLUXNET2015 sites. Daily GPP for evergreen needleleaf forests, deciduous broadleaf forests, shrublands, grasslands, and croplands shows a 7.8 %-27.6 % decrease in absolute bias, primarily attributed to reduced simulation errors during off-peak seasons of vegetation growth. Conversely, the annual total GPP error simulated using EOT-derived Vcmax25 increases slightly (2.2 %) compared to that simulated using PFT-fixed Vcmax25. This is primarily due to a significant overestimation in evergreen broadleaf forests and underestimation in croplands, despite slight increased accuracy for other PFTs. The global annual GPP simulated using Vcmax25 with seasonal variations (i.e., LCC Vcmax25 and SIF + LCC Vcmax25) yields a 4.3 %-7.3 % decrease compared to that simulated using PFT-fixed Vcmax25. Compared to FLUXCOM and GOSIF GPP products, the GPP simulated based on SIF + LCC Vcmax25 and LCC Vcmax25 demonstrates better consistency (R2 = 0.91-0.93, RMSE = 314.2-376.6 g C m-2 yr-1). This study underscores the importance of accurately characterizing the spatiotemporal variations in Vcmax25 for the accurate simulation of global vegetation productivity.

Responses of phenology to preseason drought and soil temperature for different land cover types on the Mongolian Plateau.

Drought and heat caused major disturbance in nature by interfering with plant phenology, and can also alter the vulnerability and resilience of terrestrial ecosystems. Existing research on the Mongolian Plateau has primarily focused on studying the response of the start (SOS) and end (EOS) of the growing season to drought and heat variations. However, there is still a lack of comprehensive understanding regarding the coupled effects of drought and heat on phenology across different land cover types. In this study, we retrieved SOS and EOS based on 34-year (1982-2015) normalized difference vegetation index (NDVI) dataset from Global Inventory Modeling and Mapping Studies (GIMMS). Results showed that grasslands and the Gobi-Desert show rapid advancement in SOS, and forests presented the slowest advancement in SOS, but SOS in croplands were delayed. EOS across four land cover types advanced, with the Gobi-Desert showed the highest rate of advancement and forests the lowest. Using the Palmer Drought Severity Index (PDSI) and soil temperature as the indicators of drought and thermal conditions, the responses of SOS and EOS to these two climate variables were evaluated. The advanced SOS driven by lower drought severity was detected in forests, grasslands, croplands and the Gobi-Desert. The dominant response of EOS to drought severity was positive in croplands, grasslands and forests, except for the Gobi-Desert, where drought severity had negative effects on EOS. Compared with the daily average soil temperature (STmean), the daily maximum soil temperature (STmax, daytime), and the daily minimum soil temperature (STmin, nighttime), the daily diurnal soil temperature range (DSTR, where DSTR = STmax - STmin) between night and day were the most suitable indicators for assessing the response of SOS and EOS to soil temperature. Strong negative correlation between SOS and the preseason DSTR was pronounced in all land cover types on the Mongolian Plateau. However, EOS was negatively correlated with the preseason DSTR only in the Gobi-Desert. Last but not least, normalized sensitivity assessments reveal that the negative impacts of DSTR on SOS and EOS were the main controlling factors on the Mongolian Plateau phenology, followed by the couple negative effects of drought severity and DSTR.

Preoperative CT histogram analysis to predict the expression of Ki-67 in solid pseudopapillary tumours of the pancreas.

AIM: To explore the value of preoperative computed tomography (CT) histogram features in predicting the expression status of Ki-67 in patients with solid pseudopapillary pancreatic tumours (SPTP). MATERIALS AND METHODS: This retrospective study analysed venous phase CT images of 39 patients with SPTP confirmed at surgery and histopathology and measured using the Ki-67 proliferation index from November 2015 to February 2022. According to the Ki-67 proliferation index, they were divided into high expression (Ki-67 ≥ 4%) and low expression (Ki-67 < 4%) groups. The histogram features of quantitative parameters were extracted using MaZda software, and the quantitative parameters of CT histograms were compared between groups. The receiver operating characteristic (ROC) curves of the patients were plotted according to the parameters, with statistically significant differences. The area under the curve (AUC), sensitivity, and specificity were calculated, and the effectiveness of the histogram parameters in predicting Ki-67 expression was analysed and evaluated. RESULTS: In total, 27 SPTP patients were enrolled, including 11 with high expression of Ki-67 and 16 with low expression. Comparative analysis of the Ki-67 high- and low-expression groups revealed a statistically significant in necrosis and variance (p<0.05). ROC curve analysis showed that the AUC of necrosis and variance predicting Ki-67 expression status were 0.753 and 0.841, the sensitivities were 81.8% and 81.3%, and the specificities were 68.7% and 81.8%, respectively. CONCLUSION: Preoperative CT histogram features help predict Ki-67 expression status in patients with SPTP.

China's current forest age structure will lead to weakened carbon sinks in the near future.

Forests are chiefly responsible for the terrestrial carbon sink that greatly reduces the buildup of CO2 concentrations in the atmosphere and alleviates climate change. Current predictions of terrestrial carbon sinks in the future have so far ignored the variation of forest carbon uptake with forest age. Here, we predict the role of China's current forest age in future carbon sink capacity by generating a high-resolution (30 m) forest age map in 2019 over China's landmass using satellite and forest inventory data and deriving forest growth curves using measurements of forest biomass and age in 3,121 plots. As China's forests currently have large proportions of young and middle-age stands, we project that China's forests will maintain high growth rates for about 15 years. However, as the forests grow older, their net primary productivity will decline by 5.0% ± 1.4% in 2050, 8.4% ± 1.6% in 2060, and 16.6% ± 2.8% in 2100, indicating weakened carbon sinks in the near future. The weakening of forest carbon sinks can be potentially mitigated by optimizing forest age structure through selective logging and implementing new or improved afforestation. This finding is important not only for the global carbon cycle and climate projections but also for developing forest management strategies to enhance land sinks by alleviating the age effect.

The 10-m cotton maps in Xinjiang, China during 2018-2021.

Cotton maps (10 m) of Xinjiang (XJ_COTTON10), which is the largest cotton production region of China, were produced from 2018 to 2021 through supervised classification. A two-step mapping strategy, i.e., cropland mapping followed by cotton extraction, was employed to improve the accuracy and efficiency of cotton mapping for a large region of about 1.66 million km2 with high heterogeneity. Additionally, the time-series satellite data related to spectral, textural, structural, and phenological features were combined and used in a supervised random forest classifier. The cotton/non-cotton classification model achieved overall accuracies of about 95% and 90% on the test samples of the same and adjacent years, respectively. The proposed two-step cotton mapping strategy proved promising and effective in producing multi-year and consistent cotton maps. XJ_COTTON10 agreed well with the statistical areas of cotton at the county level (R2 = 0.84-0.94). This is the first cotton mapping for the entire Xinjiang at 10-meter resolution, which can provide a basis for high-precision cotton monitoring and policymaking in China.

Positive PPD Test and TB-Ab Misdiagnosed as Tuberculosis Finally Proved as Sarcoidosis by Thoracoscopy: a Case Report.

BACKGROUND: Tuberculosis (TB) is a common infectious disease in developing countries. Tuberculosis and sarcoidosis are difficult to differentiate. We report a case of a patient who was initially misdiagnosed as tuberculosis due to positive tuberculin test (PPD test) and tuberculosis antibody (TB-Ab), which was eventually proven as sarcoidosis by thoracoscopy. METHODS: Appropriate laboratory tests are carried out and a chest CT scan, bronchoscopy, thoracoscopic pathological biopsy were done. RESULTS: Serum sedimentation was increased and tuberculosis antibody was positive. The chest CT scan showed multiple pulmonary nodules in both lungs. The bronchoscopy demonstrated no abnormality. Thoracoscopic pathology showed noncaseating granulomas and acid-fast staining was negative. CONCLUSIONS: When a patient has multiple pulmonary nodules and lymphadenopathy without obvious tuberculosis poisoning symptoms, physicians should pay attention to tuberculosis, sarcoidosis, and lung cancer. Pathology is crucial for the ultimate diagnosis.

Correlation of pericoronary adipose tissue CT attenuation values of plaques and periplaques with plaque characteristics.

AIM: To investigate the relationship between different plaque characteristics and pericoronary adipose tissue (PCAT) computed tomography (CT) attenuation values for plaques and periplaques. MATERIALS AND METHODS: The data from 188 eligible patients with stable coronary heart disease (280 lesions) who underwent coronary CT angiography between March 2021 and November 2021 were collected retrospectively. All PCAT CT attenuation values of plaques and periplaques (the area within 5 and 10 mm proximal and distal to the plaque) were calculated, and multiple linear regression was used to assess their correlation with different plaque characteristics. RESULTS: PCAT CT attenuation of plaques and periplaques was higher in non-calcified plaques (-73.38 ± 10.41 HU, -76.77 ± 10.86 HU, 79.33 ± 11.13 HU, -75.67 ± 11.24 HU, -78.63 ± 12.09 HU) and mixed plaques (-76.83 ± 8.11 HU, -79 [-85, -68.5] HU, -78.55 ± 11 HU, -78.76 ± 9.9 HU, -78.79 ± 11.06 HU) than in calcified plaques (-86.96 ± 10 HU, -84 [-92, -76] HU, -84.14 ± 11.08 HU, -84.91 ± 11.41 HU, -84.59 ± 11.69 HU; all p<0.05) and higher in distal segment plaques than in proximal segment plaques (all p<0.05). Plaque PCAT CT attenuation was lower in plaques with minimal stenosis than in plaques with mild or moderate stenosis (p<0.05). The significant determinants of PCAT CT attenuation values of plaques and periplaques were non-calcified plaques, mixed plaques, and plaques located in the distal segment (all p<0.05). CONCLUSIONS: PCAT CT attenuation values in both plaques and periplaques were related to plaque type and location.

Large diurnal compensatory effects mitigate the response of Amazonian forests to atmospheric warming and drying.

Photosynthesis and evapotranspiration in Amazonian forests are major contributors to the global carbon and water cycles. However, their diurnal patterns and responses to atmospheric warming and drying at regional scale remain unclear, hindering the understanding of global carbon and water cycles. Here, we used proxies of photosynthesis and evapotranspiration from the International Space Station to reveal a strong depression of dry season afternoon photosynthesis (by 6.7 ± 2.4%) and evapotranspiration (by 6.1 ± 3.1%). Photosynthesis positively responds to vapor pressure deficit (VPD) in the morning, but negatively in the afternoon. Furthermore, we projected that the regionally depressed afternoon photosynthesis will be compensated by their increases in the morning in future dry seasons. These results shed new light on the complex interplay of climate with carbon and water fluxes in Amazonian forests and provide evidence on the emerging environmental constraints of primary productivity that may improve the robustness of future projections.

Organizing Pneumonia Secondary to Infection with Coxiella Burnetii: a Case Report.

BACKGROUND: Organizing pneumonia is a non-specific inflammatory response to various types of damage to the lungs. It is usually considered bacterial pneumonia that has not been absorbed for more than 4 weeks, accompanied by granulomas and fibrosis. Lung lesions in patients with organizing pneumonia are usually irreversible and the prognosis is relatively poor. Coxiella burnetii can cause Q fever. Acute Q fever usually presents as a self-limiting febrile illness with a good prognosis, but there are few cases of coexisting organizing pneumonia. We report a case of organizing pneumonia secondary to Coxiella burnetii infection. METHODS: Percutaneous lung biopsy, Next-generation sequencing (NGS). RESULTS: Percutaneous lung biopsy showed the existence of organizing pneumonia, and external examination of NGS showed the existence of Coxiella burnetii infection. After symptomatic treatment with azithromycin and glucocorticoids, the patient improved and was discharged from the hospital. CONCLUSIONS: For lesions with obvious heterogeneous enhancement on chest CT imaging, percutaneous lung biopsy or bronchoscopy should be performed promptly to obtain pathological tissue, and NGS should be used for definite diagnosis if necessary.

Mycobacterium Tuberculosis Infection in AECOPD Combined with Pulmonary Embolism: a Case Report.

BACKGROUND: Mycobacterium tuberculosis belongs to the group of mycobacteria, most of which can cause a delayed hypersensitivity reaction in the body and is a bacterium that causes tuberculosis. Mycobacterium tuberculosis infection often presents with symptoms of tuberculosis toxicity and rarely with respiratory distress. At the same time, chest imaging often shows an ill-defined solid shadow in the apical and posterior segments of the upper lobe and, less frequently, in the dorsal segment of the lower lobe, and less frequently a diffuse nodular shadow. We report a case of AECOPD combined with pulmonary embolism infected with Mycobacterium tuberculosis. METHODS: Bronchoscopy, Next-generation sequencing (NGS). RESULTS: Antacid staining of bronchoalveolar lavage fluid suggested that a small amount of Mycobacterium antacid was visible. NGS was sent for examination and it suggested the presence of Mycobacterium tuberculosis with a sequence number of 5 (reference range ≥ 0). Treatment such as bronchodilation and antituberculosis was given. CONCLUSIONS: In patients with dyspnea, it is crucial to find the causative agent and to promptly improve relevant examinations such as pulmonary arteriography and bronchoscopy, and if necessary, to make a definitive diagnosis by NGS.

T-SPOT.TB Negative and Diagnosed as Interstitial Pulmonary Tuberculosis by NGS: a Case Report and Literature Review.

BACKGROUND: Tuberculosis is an airborne infectious disease with multiple morphologic changes on chest imaging. Tuberculosis-specific enzyme-linked immunospot assay (T-SPOT.TB) is widely used in the diagnosis of tuberculosis. Clinically, pulmonary tuberculosis with T-SPOT.TB negative and interstitial changes is very rare. METHODS: T-SPOT.TB, pathogenetic testing, chest CT scan, next-generation sequencing (NGS). RESULTS: Laboratory tests showed negative T-SPOT.TB and sputum antacid staining, chest CT showed interstitial fibrosis and multiple high-density shadows in both lungs, and sputum NGS showed Mycobacterium tuberculosis infection. CONCLUSIONS: Negative T-SPOT.TB and interstitial lung changes do not exclude Mycobacterium tuberculosis infection. NGS has a high specificity in the detection of pathogens in infectious diseases, especially in complex, mixed infectious diseases.

Rare Co-Infection of the Lungs with EBV and Pneumocystis Carinii in a Patient with Kidney Cancer: a Case Report.

BACKGROUND: Epstein-Barr virus (EBV) is the primary agent of infectious mononucleosis, lymphoma, and naso-pharyngeal carcinoma, but rarely involves the lungs. Pneumocystis carinii is commonly found in patients with HIV infection and is not pathogenic when the host is healthy, but opportunistic infections can occur when the body is immunocompromised, causing pneumocystis pneumonia (PCP). It is rare for both diseases to occur in the lungs of the same patient. METHODS: Next-generation sequencing (NGS), laboratory examination, chest CT scan, electronic bronchoscopy, and pathogenetic examination were used in this study. RESULTS: Laboratory tests showed (1-3)-ß-D-glucan of 889.47 pg/mL, negative human immunodeficiency virus (HIV) antibody, and negative Aspergillus immunological test. Chest CT showed multiple high-density shadows in both lungs, and EBV infection combined with Pneumocystis carinii pneumonia was confirmed by bronchoscopic biopsy and NGS examination. CONCLUSIONS: Elevated serum (1-3)-ß-D-glucan is not a specific index for infectious diseases. Bronchoscopy and the NGS has high specificity in pathogen detection of infectious diseases.

D-Dimer and Procalcitonin Improve the Sensitivity of BAP-65 Score in Predicting AECOPD Patients Admission to ICU.

BACKGROUND: The study aimed at investigating the effectiveness of the BAP-65 score combined with D-dimer and procalcitonin (PCT) in predicting admission of acute exacerbation chronic obstructive pulmonary disease (AECOPD) patients to the intensive care unit (ICU). METHODS: We conducted a retrospective study. We analyzed data from 369 patients over the age of 40 years ad-mitted to our hospital with AECOPD. All patients received blood routine measurements and BAP-65 score calculation on admission. Receiver operating characteristic curves (ROC) were used to assess the sensitivity and specificity of D-dimer, PCT, and BAP-65 scores and combined metrics in predicting the risk of admissions to the ICU of AECOPD patients. RESULTS: We found that the percentage of patients with AECOPD admitted to the ICU was 32.25% (119/369). The area under the curve (AUC) of D-dimer, PCT, and BAP-65 score in individually predicting the probability of entering the ICU of AECOPD patients were 0.74 (95% CI 0.68 - 0.80), 0.83 (95% CI 0.78 - 0.88), and 0.72 (95% CI 0.66 - 0.79), respectively. The sensitivities of D-dimer, PCT, and BAP-65 score were 0.51, 0.65, and 0.52, respectively. The specificities of D-dimer, PCT, and BAP-65 score were 0.90, 0.91, and 0.92, respectively. The AUC of D-dimer and PCT combined with BAP-65 score was 0.90 (95% CI 0.86 - 0.94), the sensitivity and specificity were 0.90 and 0.80, respectively. CONCLUSIONS: D-dimer and procalcitonin improve the sensitivity of the BAP-65 score in predicting the probability of AECOPD patients entering the ICU while having a good specificity.