In pursuit of sustainability - Spatio-temporal pathways of urban growth patterns in the world's largest megacities

Governing the future growth of the world's megacities towards higher land use efficiency is important for achieving global sustainability. We have computed statistics of the urban growth modes of 33 megacities (with ten-million-plus population) worldwide for two periods (1985-2000 and 2000-2015) and performed a hierar-chical cluster analysis to examine their urban growth patterns. Results reveal that urban growth has mostly occurred through edge expansion but also that its relative dominance has decreased due to the rising shares of the infilling and outlying growth modes. Based on the co-occurrence and changing dominance of these three urban growth modes over time, four pathways of urban growth patterns are identified- oscillating/ping pong, transition-to-densification, transition-to-sprawl, and extensive sprawl. The majority of megacities followed the oscillating/ping pong pathway, which is dominated by edge expansion and altered phases of infilling and outlying growth. However, by indicating a clear shift from edge expansion towards infilling as the dominant pathway of urban growth, the transition-to-densification pathway appears to be the most sustainable in terms of land-use efficiency, with ten megacities following this pathway. Overall, our results highlight the diverse mega -urban growth pathways across the world, particularly for megacities in the Global South which generally have higher growth rates

Dominant urban form and its relation to nighttime land surface temperature in the rapidly urbanizing National Capital Region of India

Urban form is generally accepted to be the most significant aspect controlling LST. This study analyzes the spatio-temporal urban growth pattern in India's rapidly urbanizing National Capital Region (NCR) to discern its dominant urban form based on urban sprawl metrics (USM - a neighborhood based built-up density approach) and traces its spatio-temporal growth patterns. It then gauges the relations between the landscape composition and various development modes of this dominant urban form with the ascertained nighttime LST distribution. The results of the USM based analysis show that the NCR's dominant urban form is constituted by the urban core, which has expanded markedly during the study period of 2000-2018. Within the urban core, nighttime LST increased, particularly during the fall months. Linear regression models (both non-spatial and spatial) reveal a positive relation between the nighttime LST and the built-up area and infilling growth mode. Contrarily, nighttime LST is negatively correlated with the edge-expansion and the respective areas under urbanized green and non-green open spaces. New planning approaches are thus required to restrict infilling based densification and promote well-planned edge-expansion with the designation of new green spaces as well as the greening existing non-green open spaces, particularly in areas underprovided with greenery

Persistent Deciduous Molar as an Etiology for a Maxillary Sinus Mucocele

Mucoceles are accumulations of trapped mucus, forming cystic expansile lesions. Maxillary sinus mucoceles are rare amongst paranasal sinus mucoceles, usually being a late sequel of Caldwell-Luc surgery. We present a case of a maxillary sinus mucocele due to a persistent carious deciduous molar in a middle aged patient, reported to highlight its unusual etiology