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One of the effective ways to improve the productivity of mixed forests is enhancing resource use efficiency based on the biological characteristics of afforestation tree species. Resource use efficiency is affected by tree species interactions and environmental conditions through applying appropriate cultivation patterns. In this study, we evaluated two estimating methods for the productivity of mixed forest, analyzed the internal mechanism of interspecific tree competition and complementary effects on mixed forest productivity, clarified external factors of growth space and habitat factors control over productivity of mixed forest, discussed the effects of tree species composition, stand density and site quality on productivity, and illustrated the productivity trajectory during the development of mixed forests. Finally, based on the knowledge of the internal mechanism and habitat factors affecting the formation of mixed forest productivity, we focused on the key scientific issues that urgently need to be solved in the construction of the current mixed forests cultivation patterns, and put forward future research directions, including improving the productivity estimation system, establishing long-term mixed forest observation field, enhancing the research on the comprehensive effect of various cultivation measures, and reinforcing research of the growth and development dynamics in mixed forests.
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Forests , Trees , Ecosystem , EfficiencyABSTRACT
OBJECTIVES: To explore the etiology composition and outcomes of pediatric chronic critical illness (PCCI) in the pediatric intensive care unit (PICU). METHODS: The children who were hospitalized in the PICU of Dongguan Children's Hospital Affiliated to Guangdong Medical University and met the diagnostic criteria for PCCI from January 2017 to December 2022 were included in the study. The etiology of the children was classified based on their medical records and discharge diagnoses. Relevant clinical data during hospitalization were collected and analyzed. RESULTS: Among the 3 955 hospitalized children in the PICU from January 2017 to December 2022, 321 cases (8.12%) met the diagnostic criteria for PCCI. Among the 321 cases, the most common etiology was infection (71.3%, 229 cases), followed by unintentional injury (12.8%, 41 cases), postoperation (5.9%, 19 cases), tumors/immune system diseases (5.0%, 16 cases), and genetic and chromosomal diseases (5.0%, 16 cases). Among the 321 cases, 249 cases (77.6%) were discharged after improvement, 37 cases (11.5%) were discharged at the request of the family, and 35 cases (10.9%) died in the hospital. Among the deaths, infection accounted for 74% (26/35), unintentional injury accounted for 17% (6/35), tumors/immune system diseases accounted for 6% (2/35), and genetic and chromosomal diseases accounted for 3% (1/35). From 2017 to 2022, the proportion of PCCI in PICU diseases showed an increasing trend year by year (P<0.05). Among the 321 children with PCCI, there were 148 infants and young children (46.1%), 57 preschool children (17.8%), 54 school-aged children (16.8%), and 62 adolescents (19.3%), with the highest proportion in the infant and young children group (P<0.05). The in-hospital mortality rates of the four age groups were 14.9% (22/148), 8.8% (5/57), 5.6% (3/54), and 8.1% (5/62), respectively. The infant and young children group had the highest mortality rate, but there was no statistically significant difference among the four groups (P>0.05). CONCLUSIONS: The proportion of PCCI in PICU diseases is increasing, and the main causes are infection and unintentional injury. The most common cause of death in children with PCCI is infection. The PCCI patient population is mainly infants and young children, and the in-hospital mortality rate of infant and young children with PCCI is relatively high.
Subject(s)
Child, Hospitalized , Critical Illness , Adolescent , Infant , Child, Preschool , Humans , Child , Prognosis , Chronic Disease , Intensive Care Units, PediatricABSTRACT
The aim of this study was to clarify the mechanism by which thinning alters stand structure and affects forest productivity by characterizing changes in stand quantitative maturity age, stand diameter distribution, structural heterogeneity, and forest productivity of Chinese fir plantations at different thinning times and intensities. Our findings provide insights into how the density of stands could be modified to enhance the yield and timber quality of Chinese fir plantations. The significance of differences in individual tree volume, stand volume, and timber merchantable volume was determined using one-way analysis of variance and post hoc Duncan tests. The stand quantitative maturity age was obtained using the Richards equation. The quantitative relationship between stand structure and productivity was determined using a generalized linear mixed model. We found that (1) the quantitative maturity age of Chinese fir plantations increased with thinning intensity, and the quantitative maturity age was much greater under commercial thinning than under pre-commercial thinning. (2) Individual tree volume and the proportion of medium-sized and large-sized timber merchantable volume increased with stand thinning intensity. Thinning promoted increases in stand diameter. pre-commercially thinned stands were dominated by medium-diameter trees when the quantitative maturity age was reached, whereas commercially thinned stands were dominated by large-diameter trees. The living trees volume will decrease immediately after thinning, and then it will gradually increase with the age of the stand. When the stand volume included both living trees volume and thinned volume, thinned stands increased stand volume compared with unthinned stands. In pre-commercial thinning stands, the greater the intensity of thinning, the greater the increase in stand volume, and the opposite was true for commercial thinning. (3) Thinning also reduced heterogeneity in stand structure, which was lower after commercial thinning than after pre-commercial thinning. The productivity of pre-commercially thinned stands increased with thinning intensity, whereas that of commercially thinned stands decreased with thinning intensity. (4) The structural heterogeneity of pre-commercially and commercially thinned stands was negatively and positively correlated with forest productivity, respectively. In the Chinese fir plantations in the hilly terrain of the northern Chinese fir production area, when pre-commercial thinning was performed in the ninth year to a residual density of 1750 trees per hectare, the stand quantitative maturity age was reached in year 30, medium-sized timber accounted for 75.2% of all trees, and the stand volume was 667.9 m3 per hectare. This thinning strategy is favorable for producing medium-sized Chinese fir timber. When commercial thinning was performed in year 23, the optimal residual density was 400 trees per hectare. When the stand quantitative maturity age was reached in year 31, large-sized timber accounted for 76.6% of all trees, and the stand volume was 574.5 m3 per hectare. This thinning strategy is favorable for producing large-sized Chinese fir timber.
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OBJECTIVES: To study the clinical characteristics of ultrasound-guided central venous catheterization at various sites in infants with shock, and to explore how to quickly select the site for central venous puncture in infants with shock. METHODS: The medical data of 112 infants who were diagnosed with shock and underwent central venous catheterization in the Pediatric Intensive Care Unit, Dongguan Children's Hospital Affiliated to Guangdong Medical University, from January 2016 to December 2020 were reviewed retrospectively. The patients were divided into an ultrasound group (n=70) and a body surface location group (n=42) according to whether the catheterization was carried out under ultrasound guidance. The application of ultrasound-guided catheterization at various sites in infants was summarized and analyzed, and the success rate of one-time puncture, overall success rate, catheterization time, and complications were compared between these sites. RESULTS: Compared with the body surface location group, the ultrasound group had a significantly higher success rate of one-time puncture, a significantly shorter catheterization time, and a significantly reduced incidence rate of complications in internal jugular vein and femoral vein catheterizations (P<0.05). In the ultrasound group, the proportion of internal jugular vein catheterization was the highest (51%, 36/70), followed by femoral vein catheterization (33%, 23/70), and subclavian vein catheterization (16%, 11/70). For the comparison between different puncture sites under ultrasound guidance, internal jugular vein catheterization showed the shortest time of a successful catheterization [5.5 (5.0, 6.5) minutes] (P<0.05). There was no significant difference in the incidence rate of complications among the different puncture sites groups (P>0.05). CONCLUSIONS: In infants with shock, ultrasound-guided internal jugular vein catheterization can be used as the preferred catheterization method for clinicians.
Subject(s)
Catheterization, Central Venous , Catheterization, Central Venous/adverse effects , Child , Humans , Infant , Jugular Veins/diagnostic imaging , Retrospective Studies , Ultrasonography , Ultrasonography, InterventionalABSTRACT
BACKGROUND: Sweet tea, which functions as tea, sugar and medicine, was listed as a new food resource in 2017. Flavonoids are the main medicinal components in sweet tea and have significant pharmacological activities. Therefore, the quality of sweet tea is related to the content of flavonoids. Flavonoid content in plants is normally determined by time-consuming and expensive chemical analyses. The aim of this study was to develop a methodology to measure three constituents of flavonoids, namely, total flavonoids, phloridin and trilobatin, in sweet tea leaves using near-infrared spectroscopy (NIR). RESULTS: In this study, we demonstrated that the combination of principal component analysis (PCA) and NIR spectroscopy can distinguish sweet tea from different locations. In addition, different spectral preprocessing methods are used to establish partial least squares (PLS) models between spectral information and the content of the three constituents. The best total flavonoid prediction model was obtained with NIR spectra preprocessed with Savitzky-Golay combined with second derivatives (SG + D2) (RP2 = 0.893, and RMSEP = 0.131). For trilobatin, the model with the best performance was developed with raw NIR spectra (RP2 = 0.902, and RMSEP = 2.993), and for phloridin, the best model was obtained with NIR spectra preprocessed with standard normal variate (SNV) (RP2 = 0.818, and RMSEP = 1.085). The coefficients of determination for all calibration sets, validation sets and prediction sets of the best PLS models were higher than 0.967, 0.858 and 0.818, respectively. CONCLUSIONS: The conclusion indicated that NIR spectroscopy has the ability to determine the flavonoid content of sweet tea quickly and conveniently.
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BACKGROUND: Wood basic density (WBD) is one of the most crucial wood property in tree and mainly determined the end use of wood for industry. However, the measurement WBD is time- and cost-consuming, which an alternatively fast and no-destructive measurement is needed. In this study, capability of NIR spectroscopy combined with partial least squares regression (PLSR) to quantify the WBD were examined in multiple wood species. To obtain more accurate and robust prediction models, the grain angle (0° (transverse surface), 45°, 90° (radial surface)) influence on the collection of solid wood spectra and a comparison of found variable selection methods for NIR spectral variables optimization were conducted, including significant Multivariate Correlation (sMC), Regularized elimination procedure (Rep), Iterative predictor weighting (Ipw) and Genetic algorithm (Ga). Models made by random calibration data selection were conducted 200 times performance evaluation. RESULTS: These results indicate that 90° angle models display relatively highest efficiency than other angle models, mixed angle model yield a satisfied WBD prediction results as well and could reduce the influence of grain angle. Rep method shows a higher efficiency than other methods which could eliminate the uninformative variables and enhance the predictive performance of 90° angle and mix angle models. CONCLUSIONS: This study is potentially shown that the WBD (g/cm3) on solid wood across grain angles and varies wood species could be measured in a rapid and efficient way using NIR technology. Combined with the PLSR model, our methodology could serve as a tool for wood properties breeding and silviculture study.
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BACKGROUND: Plant traits related to nutrition have an influential role in tree growth, tree production and nutrient cycling. Therefore, the breeding program should consider the genetics of the traits. However, the measurement methods could seriously affect the progress of breeding selection program. In this study, we tested the ability of spectroscopy to quantify the specific leaf nutrition traits including anthocyanins (ANTH), flavonoids (FLAV) and nitrogen balance index (NBI), and estimated the genetic variation of these leaf traits based on the spectroscopic predicted data. Fresh leaves of Sassafras tzumu were selected for spectral collection and ANTH, FLAV and NBI concentrations measurement by standard analytical methods. Partial least squares regression (PLSR), five spectra pre-processing methods, and four variable selection algorisms were conducted for the optimal model selection. Each trait model was simulated 200 times for error estimation. RESULTS: The standard normal variate (SNV) to the ANTH model and 1st derivatives to the FLAV and NBI models, combined with significant Multivariate Correlation (sMC) algorithm variable selection are finally regarded as the best performance models. The ANTH model produced the highest accuracy of prediction with a mean R2 of 0.72 and mean RMSE of 0.10%, followed by FLAV and NBI model (mean R2 of 0.58, mean RMSE of 0.11% and mean R2 of 0.44, mean RMSE of 0.04%). High heritability was found for ANTH, FLAV and NBI with h2 of 0.78, 0.58 and 0.61 respectively. It shows that it is beneficial and possible for breeding selection to the improvement of leaf nutrition traits. CONCLUSIONS: Spectroscopy can successfully characterize the leaf nutrition traits in living tree leaves and the ability to simultaneous multiple plant traits provides a promising and high-throughput tool for the quick analysis of large size samples and serves for genetic breeding program.
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Drought is a climatic event that considerably impacts plant growth, reproduction and productivity. Toona sinensis is a tree species with high economic, edible and medicinal value, and has drought resistance. Thus, the objective of this study was to dynamically monitor the physiological indicators of T. sinensis in real time to ensure the selection of drought-resistant varieties of T. sinensis. In this study, we used near-infrared spectroscopy as a high-throughput method along with five preprocessing methods combined with four variable selection approaches to establish a cross-validated partial least squares regression model to establish the relationship between the near infrared reflectance spectroscopy (NIRS) spectrum and physiological characteristics (i.e., chlorophyll content and nitrogen content) of T. sinensis leaves. We also tested optimal model prediction for the dynamic changes in T. sinensis chlorophyll and nitrogen content under five separate watering regimes to mimic non-destructive and dynamic detection of plant leaf physiological changes. Among them, the accuracy of the chlorophyll content prediction model was as high as 72%, with root mean square error (RMSE) of 0.25, and the RPD index above 2.26. Ideal nitrogen content prediction model should have R 2 of 0.63, with RMSE of 0.87, and the RPD index of 1.12. The results showed that the PLSR model has a good prediction effect. Overall, under diverse drought stress treatments, the chlorophyll content of T. sinensis leaves showed a decreasing trend over time. Furthermore, the chlorophyll content was the most stable under the 75% field capacity treatment. However, the nitrogen content of the plant leaves was found to have a different and variable trend, with the greatest drop in content under the 10% field capacity treatment. This study showed that NIRS has great potential for analyzing chlorophyll nitrogen and other elements in plant leaf tissues in non-destructive dynamic monitoring.
