Effects of rapid urbanisation on the urban thermal environment between 1990 and 2011 in Dhaka Megacity, Bangladesh

This study investigates the influence of land-use/land-cover (LULC) change on land surface temperature (LST) in Dhaka Megacity, Bangladesh during a period of rapid urbanisation. LST was derived from Landsat 5 TM scenes captured in 1990, 2000 and 2011 and compared to contemporaneous LULC maps. We compared index-based and linear spectral mixture analysis (LSMA) techniques for modelling LST. LSMA derived biophysical parameters corresponded more strongly to LST than those produced using index-based parameters. Results indicated that vegetation and water surfaces had relatively stable LST but it increased by around 2 °C when these surfaces were converted to built-up areas with extensive impervious surfaces. Knowledge of the expected change in LST when one land-cover is converted to another can inform land planners of the potential impact of future changes and urges the development of better management strategies

Optimization of urban cooling strategies for parking lots in hot and dry climates: Case study of Las Vegas and Adelaide

Urban microclimates are distinguished by the balance between solar gain and heat lost from building envelope and ground surfaces, by convective heat exchange, and by the generation of anthropogenic heat within the city. Global climate change and the urban heat island (UHI) effect—whereby cities are up to 8 °C hotter than their surrounding countryside—carry growing threats to outdoor living, public health, and urban energy demand. Urban heat stress intensifies in cities with hot and dry summer climates such as Las Vegas (USA) and Adelaide (Australia), where the temperature goes frequently above 36 °C (97 °F). Both cities have a dry, hot, and arid climate. Possible adaptation countermeasures include cool surfaces, urban greenery, and active cooling with the consideration of higher demand for water and energy, and potential winter cooling penalties. Large open-air parking lots appear in many modern cities around shopping malls, hospitals and public venues and provide essential access to these public facilities. In this context, a comparative study of different cooling strategies informs more effective decision making for the design and implementation of UHI adaptation and mitigation strategies. This chapter compares urban cooling strategies for typical parking lots in Downtown Las Vegas, Adelaide CBD and the suburban context. Cool surface materials, tree canopy, evaporative cooling and shading scenarios are estimated, and cooling benefits and side effects of each intervention are discussed. The research shows that planting trees between car parking spaces is vital to most urban environments, especially for parking lots where it leads to 1–5 °C summer cooling.Ehsan Sharifi, Phillip Zawarus, Steffen Lehman

Depopulation of interstitial cells of cajal in chagasic megacolon: towards tailored surgery? Depleção de células intersticiais de Cajal no megacólon chagásico: a caminho do tratamento cirúrgico individualizado?

BACKGROUND: The mechanism of constipation in patients with Chagasic megacolon remains partially explained. In these patients, it was recently demonstrated a reduction in the population of interstitial cells of Cajal. AIM: To evaluate density of Cajal cells in the surgically resected colon of Chagasic patients in comparison to control patients, and to verify possible association between preoperative and postoperative bowel function of Chagasic patients and colonic cell count. METHOD: Sixteen patients with Chagasic megacolon were operated on. Clinical pre- and post-operative evaluation using the Cleveland Clinic Constipation Score was undertaken. Resected colons were examined. Cajal cells were identified by immunohistochemistry using anti-CD117 antibody. The mean cell number was compared to resected colons from 16 patients with non-obstructive sigmoid cancer. Association between pre-and post-operative constipation scores and cell count for megacolon patients was evaluated using the Pearson coefficient correlation test (r). RESULTS: A reduced number of Cajal cells [cells per field: 2.84 (0-6.6) vs. 9.68 (4.3-13) - p<0.001] was observed in the resected colon of Chagasic patients when compared to colon cancer patients. No correlation between constipation score before (r=-0.205; p=0.45) or after surgery (r=0,291; p=0.28) and cell count for megacolon patients was observed. CONCLUSIONS: Patients with Chagasic megacolon display marked reduction of interstitial cells of Cajal when compared to non-Chagasic patients. An association of constipation severity and Cajal cells depopulation in Chagasic megacolon could not be demonstrated.<br>RACIONAL: A fisiopatologia da constipação intestinal nos pacientes portadores de megacólon chagásico permanece parcialmente esclarecida. Recentemente demontrou-se que nesses pacientes, o contingente de células intersticiais de Cajal está reduzido assim como ocorre em outros distúrbios funcionais gastrointestinais. OBJETIVO: Avaliar a densidade de células intersticiais de Cajal no intestino ressecado de pacientes submetidos a tratamento cirúrgico eletivo de megacólon chagásico em comparação com a observada no cólon de pacientes controles, e verificar possível associação entre o grau de constipação intestinal de pacientes com megacólon chagásico no pré e no pós-operatório e o grau de despopulação de células de Cajal. MÉTODO: Dezesseis pacientes com megacólon chagásico foram operados. A avaliação da função intestinal através do escore de constipação da Cleveland Clinic foi registrada antes e após a operação. O espécime cirúrgico foi examinado e as células de Cajal foram identificadas pela técnica imunoistoquímica empregando o anticorpo anti-CD117 (c-kit). O número médio de células de Cajal nos megacólons foi comparado com o de cólons ressecados de 16 pacientes [7 mulheres; média de idade de 62,8 (23-84)] operados de câncer não-obstrutivo do sigmóide. A associação entre o escore de constipação no pré e no pós-operatório e a contagem de células de Cajal foi medida através do coeficente de correlação de Pearson (r). RESULTADOS: Redução significativa no número de células de Cajal (células por campo de 400X: 2,84 (0-6,6) vs. 9,68 (4,3-13) - ] foi observada nos megacólons quando comparados ao espécime de pacientes operados por câncer. Não foi observada associação entre o escore de constipação pré (r=-0.205; p=0.45) ou pós-operatório (r=0,291; p=0.28) a a contagem de células de Cajal para os pacientes com megacólon. CONCLUSÕES: Pacientes com megacólon chagásico exibem acentuada redução no número de células intersticiais de Cajal no intestino grosso. Não se pôde demonstrar associação entre grau de constipação e a intensidade da despopulação de células de Cajal no presente estudo