Analysis of Green Total Factor Productivity of Grain and Its Dynamic Distribution: Evidence from Poyang Lake Basin, China

Based on the grain production data of the counties (cities, districts) in Poyang Lake Basin, this paper uses the productivity index of Epsilon Based Measure of Malmquist Luenberger (EBM-ML Index) to analyse the green total factor productivity (GTFP) of grain in Poyang Lake Basin. Kernel density function and Markov analysis are used to discuss the dynamic evolution process of the distribution of GTFP of grain. The results show the following: (1) From the time dimension, the GTFP of grain is on the rise and fluctuates more frequently from 2001 to 2017, and its trend of change is determined by the combination of technical efficiency and technological progress. Moreover, from a spatial dimension, the number of counties (cities, districts) with GTFP of grain greater than 1.0 has shown an overall increase, indicating that the overall level of GTFP of grain is increasing. (2) According to the kernel density estimation results, the crest of the main peak of the kernel density curve corresponding to the GTFP of grain in Poyang Lake Basin shifts to the right, and the area formed by the right part of the GTFP of grain corresponding to the crest of the main peak of its kernel density curve gradually increases. The peak of the kernel density curve changes from “multi-peak mode” to “single-peak mode,” and the height of the main peak of the kernel density curve of GTFP of grain shows an overall decrease. Meanwhile, the right tail of the kernel density curve shows an overall extending trend. (3) According to the estimation results of the Markov chain, the GTFP of grain in Poyang Lake Basin is highly mobile from 2001 to 2017, and the counties (cities, districts) have a certain degree of agglomeration in the low, medium-low, medium-high and high levels. In other words, the long-term equilibrium state of growth of GTFP of grain remains dispersed in the state space of four level types, indicating that the divergence state of GTFP of grain in counties (cities, districts) of Poyang Lake Basin will continue for a long time in the future. The study reveals the evolution and dynamic change of GTFP of grain in Poyang Lake Basin, which has important theoretical significance and practical value for optimizing the spatial pattern and realizing the balanced development of GTFP among counties (cities, districts) of Poyang Lake Basin and consolidating China’s food security strategy.

Modelling Inter-pixel Spatial Variation of Surface Urban Heat Island Intensity

Context Surface urban heat island intensity (SUHII) is a classical measure, which is sensitive to the selection of pixels/measurements representative of urban and rural areas, and overlooks pixel-level SUHII variation and thermodynamics of heterogeneous urban landscape. Accounting inter-pixel landscape heterogeneity in SUHII would capture inter-pixel thermodynamics and reveal complicated micro-thermal situations, contribute to assessment of potential heat risks at micro-pixel scale. Objectives This study develops [[EQUATION]] using pixel-based sharpening enhancement method. It integrates a pixel’s LST magnitude that reflects a city’s thermal context with local SUHII considering landscape variations and cognate thermal interactions of neighboring pixels. Methods [[EQUATION]] is constructed using MODIS LST product for Guangzhou (south China) in the summer season of 2015 through cloud-based GEE platform. Its effectiveness is tested using a bivariate choropleth map and Gaussian density curve with stepwise increments of the thermal influence from neighboring pixels. Results We found that (1) local SUHII variations are sensitive to the spatial configuration of a center pixel’s land use and that of its neighbors; (2) [[EQUATION]] makes more pronounced those spots that are heat per se (with higher original LST), but also receive additional heat load from adjacent pixels due to land-use homogeneity; (3) the effectiveness of [[EQUATION]] could be demonstrated by Gaussian density curve. Conclusions This paper proposed a new SHUII indicator, [[EQUATION]] , which models inter-pixel spatial variation of SHUI and highlights how neighboring pixels’ homogenous/heterogeneous land-use and associated thermal properties could affect center pixels’ thermal characteristics via either reinforcement or mitigation of heat load.

Carotid webs produce greater hemodynamic disturbances than atherosclerotic disease: a DSA time–density curve study

BackgroundCarotid webs (CaWs) are associated with ischemic strokes in younger patients without degrees of stenosis that are traditionally considered clinically significant.ObjectiveTo compare the hemodynamic parameters in the internal carotid artery (ICA) bulbar segment in patients with CaW with those in patients with atherosclerotic lesions using time–density curve (TDC) analysis of digital subtraction angiography (DSA) images.MethodsWe retrospectively assessed DSA images of 47 carotid arteries in 41 adult patients who underwent ICA catheter angiography for evaluation after ischemic stroke. Hemodynamic parameters, including full width at half maximum (FWHM) and area under the time–density curve (AUC) as proxies for increased flow stasis, were calculated using TDC analyses of a region of interest (ROI) in the ICA bulb immediately rostral to the web/atherosclerotic plaque, relative to a standardized ROI in the ipsilateral distal common carotid artery (eg, relative FWHM (rFWHM)). Hemodynamic parameters were compared using non-parametric Kruskal-Wallis tests. Logistic regression was used to predict CaW versus mild/moderate atherosclerosis for each hemodynamic parameter, adjusting for degree of stenosis.ResultsMean age of patients was 56.0±13 years, with 22 (53.7%) women. 17 CaWs, 22 atherosclerotic plaques (15 mild/moderate and 7 severe), and eight normal carotid arteries were assessed. Significant between-group differences were present in the relative total AUC (p<0.001), relative AUC at wash out (p=0.031), and relative FWHM (p=0.001). Logistic regression to predict CaW versus mild/moderate atherosclerosis showed that rAUC total had the highest predictive value (pAUC=0.96, 95% CI 0.90 to 1.00), followed by rFWHM (0.87, 95% CI 0.74 to 1.00), and rAUC WO (0.74, 95% CI (0.57 to 0.91).ConclusionCaW results in larger local hemodynamic disruption, characterized by flow stasis, than mild/moderate carotid atherosclerotic lesions, suggesting that CaWs may produce larger regions of thrombogenic flow stasis.

Clinical validation of 2D perfusion angiography using Syngo iFlow software during peripheral arterial interventions

Objective Endovascular surgery is an important treatment modality in peripheral arterial disease. Digital subtraction angiography is the standard post revascularisation diagnostic tool to locate lesions and to evaluate the effect of an intervention. However, interpretation of digital subtraction angiography images is subjective and it is difficult to determine whether revascularisation has been sufficient for clinical improvement. A new technique is 2D perfusion angiography, which creates a 2D colour map and time density curve from the digital subtraction angiography scan for an objective evaluation of the results. However, its clinical relevance is unknown. The aim is to evaluate the association between 2D perfusion angiography parameters and clinical outcome after peripheral arterial interventions. Methods In this retrospective study, post revascularisation angiographic data and clinical data were reviewed of patients who underwent treatment of femoral-popliteal or femoral-tibial arteries. The outcome was assessed at three time points using three classification systems for peripheral arterial disease: Fontaine classification, American Medical Association whole person impairment classification (AMA) and average wound, ischemia, foot infection score. Post revascularisation angiographic data consisted of time density curves of the foot and lower leg which were extracted from the Syngo iFlow system (Siemens Healthineers). For each time density curve, five descriptive parameters were calculated: time of arrival, time to peak, mean transit time, wash-in rate and area under the curve. The association between the time density curve parameters and peripheral arterial disease classification systems was assessed using a regression analysis. Results Between July 2016 and December 2018, 103 patients underwent peripheral endovascular interventions in the hybrid operating room; 39 patients were suitable for analysis, of which 28 patients underwent digital subtraction angiography of the lower leg, 3 patients underwent digital subtraction angiography of the foot and 8 patients underwent digital subtraction angiography of both regions. Limited significant relations were found for time of arrival with Fontainde classification (B = 0.806, p = 0.043) and area under the curve with AMA classification (B = −0.027, p = 0.047). Conclusion In this retrospective study, time density curve parameters (time of arrival and area under the curve), measured in the lower leg, showed a limited significant association with two classification systems for peripheral arterial disease. Future prospective studies to determine the clinical relevance of this 2D perfusion angiography method should focus on standardisation of angiography protocols and comparison of pre- and post-intervention parameters.

Thermal Conductivity of Silicone Rubber Filled with Al2O3

Crosslinker (polyvinylsilicone oil, C gum) and curing agent (2, 5-bis (tert-butyl peroxy)-2, 5-dimethyl hexane, DBPMH) were used to change the crosslink density of the thermal conductivity of silicone rubber filled with Al2O3. The results show that the thermal conductivity of silicone rubber changed with its degree of crosslinking. When the Al2O3 loading was 5 vol. % and a completely continuous conducting network had not formed, the thermal conductivity of the vulcanizates decreased with increasing crosslink density. The thermal conductivity of the vulcanizate with a suitable amount of C gum increased to 53%, and the tensile strength increased by 0.8 MPa compared to the vulcanizate without C gum. When the Al2O3 loading was 30 vol. % and a completely continuous conducting network had formed, the crosslink density of vulcanizates changed as the amount of DBPMH changed. The thermal conductivity of vulcanizates first decreased and then increased with increasing crosslink density. There was a valley value in the thermal conductivity–crosslink density curve.