Assessment of land use change of ecological green wedge and cooling island effect: A case study of Wuhan, China.

The construction of urban ecological green wedges, which can mitigate the heat island effect through cooling and ventilation effects, is an important way to enhance the adaptation of cities to climate change. Dynamic monitoring and periodic assessment of both the conservation status and cooling effect of ecological green wedges is a key to ensure the heat mitigation benefits. Based on multi-source remote sensing data, we systematically analyzed the land use changes of six ecological green wedges in Wuhan in 2013 and 2020 using the methods of Markov transfer matrix, land use dynamics, and comprehensive index of land use degree, and evaluated the changes in surface temperature of the ecological green wedges and their cooling island effect. Results showed that the ecological green wedges in Wuhan generally had a large amount of construction land encroaching on ecological land from 2013 to 2020, with the water decreased the most. With the continuous deterioration of ecological green wedges, their land surface temperatures showed rising trends, together with significant weakening trends in cooling island effects. Among all the six wedges, the Dadonghu, Tangxun, and Wuhu exhibited relatively better ecological conservation, slighter land use change and lower overall development degree. Qinglinghu and Houguanhu demonstrated average levels of conservation. Fuhe experienced the most severe change under the significant influence of the westward policy of Wuhan City, with the proportion of water decreasing by 7.1%, warming up by 3.00 ℃, and the largest reduction in cooling distance for the cooling island effect, amounting to about 210 m. The results provided scientific evidence for the urban heat island mitigation-oriented planning and management of ecological green wedges for Wuhan City.

[Prevalence and risk factors of asymptomatic intracranial vascular stenosis in patients with essential hypertension].

OBJECTIVE: The aim of the study was to determine the prevalence and the distribution pattern of lesion site of intracranial vascular stenosis and to identify risk factors for the stenosis in patients with essential hypertension. METHODS: A total of 231 consecutive inpatients with essential hypertension were included in this study. Patients with the history of cerebrovascular diseases and relevant neurological symptoms were excluded. Intracranial vascular stenosis (>50% diameter reduction) was detected using CT angiography (CTA). RESULTS: Of 231 patients, 69 (29.87%) had intracranial artery stenosis. The most common stenosis site is middle cerebral artery (43.69%), followed by carotid siphon (20.39%). The stenosis in internal carotid arterial system (78.64%) was more common than in vertebrobasilar arterial system (21.56%, P < 0.05). The patients with intracranial vascular stenosis were older, had longer history of hypertension, higher levels of systolic blood pressure, higher plasma cholesterol, higher LDL-C. Lp (a), higher urinary microalbumin excretion, thicker ventricular septum, and lower levels of HDL-C than the patients without stenosis. Logistic analysis showed that systolic blood pressure (OR 1.650, 95% CI 1.134 - 2.400, P = 0.023), course of hypertension (OR 1.238, 95% CI 1.072 - 1.429, P = 0.006), LDL-C (OR 2.103, 95% CI 1.157 - 3.823, P = 0.014) and type 2 diabetes (OR 2.325, 95% CI 1.161 - 4.341, P = 0.011) were the independent risk factors of asymptomatic intracranial arterial stenosis. CONCLUSIONS: Nearly 30% inpatients with essential hypertension had asymptomatic intracranial artery stenosis. The most common site of stenosis was middle cerebral artery. Hypertension, dyslipidemia and diabetes were risk factors for the development of intracranial arterial stenosis.