Performance analysis of two typical greenhouse lettuce production systems: Commercial hydroponic production and traditional soil cultivation

Introduction: Due to the shortage of land and water resource, optimization of systems for production in commercial greenhouses is essential for sustainable vegetable supply. The performance of lettuce productivity and the economic benefit in greenhouses using a soil-based system (SBS) and a hydroponic production system (HPS) were compared in this study. Methods: Experiments were conducted in two identical greenhouses over two growth cycles (G1 and G2). Three treatments of irrigation volumes (S1, S2, and S3) were evaluated for SBS while three treatments of nutrient solution concentration (H1, H2, and H3) were evaluated for HPS; the optimal levels from each system were then compared. Results and discussion: HPS was more sensitive to the effects of environmental temperature than SBS because of higher soil buffer capacity. Compared with SBS, higher yield (more than 134%) and higher water productivity (more than 50%) were observed in HPS. We detected significant increases in ascorbic acid by 28.31% and 16.67% and in soluble sugar by 57.84% and 32.23% during G1 and G2, respectively, compared with SBS. However, nitrate accumulated in HPS-grown lettuce. When the nutrient solution was replaced with fresh water 3 days before harvest, the excess nitrate content of harvested lettuce in HPS was removed. The initial investment and total operating cost in HPS were 21.76 times and 47.09% higher than those in SBS, respectively. Consideration of agronomic, quality, and economic indicators showed an overall optimal performance of the H2 treatment. These findings indicated that, in spite of its higher initial investment and requirement of advanced technology and management, HPS was more profitable than SBS for commercial lettuce production

Analysis of Numerical Measure and Numerical Integration Based on Measure

We present a convergence analysis for a general numerical method to estimate measure function. By combining Lagrange interpolation, we propose a specific method for approximating the measure function and analyze the convergence order. Further, we analyze the error bound of numerical measure integration and prove that the numerical measure integration can decrease the singularity for singular integrals. Numerical examples are presented to confirm the theoretical results

Adipokines are Associated With Hypertension in Metabolically Healthy Obese (MHO) Children and Adolescents: A Prospective Population-Based Cohort Study

Background: The potential mechanism underlying the relationship between the risk of cardiovascular diseases and metabolically healthy obese (MHO) individuals remains unclear. The aim of the study was to prospectively investigate the potential role of the adipokines in the association between the MHO phenotype and hypertension in children and adolescents. Methods: A total of 1184 participants at baseline were recruited from a cohort of the Beijing Child and Adolescent Metabolic Syndrome (BCAMS) study. The participants were classified according to their body mass index (BMI) and metabolic syndrome (MS) components. The levels of the adipokines, including leptin, adiponectin, and resistin, were measured. Results: MHO individuals had higher leptin levels (11.58 ug/L vs 1.20 ug/L), leptin/adiponectin ratio (1.18 vs 0.07), and lower adiponectin (11.65 ug/L vs 15.64 ug/L) levels compared to metabolically healthy normal-weight individuals (all P < 0.05). Compared to metabolically healthy normal-weight individuals, the prevalence of high leptin levels (26.5% vs 0.4%), low adiponectin levels (17.9% vs 6.3%) and a high leptin/adiponectin ratio (26.0% vs 2.1%) was higher in MHO individuals (all P < 0.01). The MHO individuals with abnormal adipokines were significantly more likely to developing hypertension (high leptin, relative risk 11.04; 95% confidence interval, 1.18–103.35; and high leptin/adiponectin ratio, relative risk 9.88; 95% confidence interval, 1.11–87.97) compared to metabolically healthy normal-weight individuals with normal adipokine levels. Conclusions: The abnormal adipokine levels contribute to the increased hypertension risk in MHO children and adolescents. The non-traditional risk factors should be highlighted in MHO children and adolescents in clinical practice and research