Temporal variations of polar cap 0I 5577-Å airglow

Limb observations of the E-region 0I 5577-Å airglow in the polar caps were obtained during 1971 and 1972 from the ISIS-2 satellite. In the southern polar cap the emission rate decreased to a broad minimum of 100 R near solstice, then increased later in the winter. In the northern polar cap a maximum was observed in November. In addition to large daily variations, there were enhancements that lasted several weeks. From a correlation analysis using both satellite data supplemented by the more extensive data base of Mullen et al. (1977,Planet. Space Sci.25, 23) and stratospheric temperatures, it is clear that stratospheric warmings result in polar cap airglow enhancements. The most plausible cause of these airglow enhancements appears to be increased meridional transport of atomic oxygen into the polar cap.     

Generic rule-sets for automated detection of urban tree species from very high-resolution satellite data

The sustainable management and monitoring of urban forests is an important activity in the urbanized world, and operational approaches require information about the status of urban trees to determine the best strategy. One limitation in urban forest studies is the detection and discrimination of tree species using limited training data. Thus, this study focuses on developing generic rule sets from high-resolution WorldView-2 imagery in conjunction with spectral, spatial, colour and textural information for automated urban tree species detection. The object-based image analysis and its combination with statistical analysis of object features is utilized for this purpose. Results of attribute selection indicated that from 55 attributes, only 26 were useful to discriminate urban tree species, namely Messua ferrea L., Samanea saman and Casuarina sumatrana. Finally, the high overall accuracy, approximately 86.87% with kappa of 0.75 confirmed the transferability of the generic model.     

Monitoring and analysing the Emirate of Dubai’s land use/land cover changes: an integrated,low-cost remote sensing approach

This study presents a modified low-cost approach, which integrates the spectral angle mapper and image difference algorithms in order to enhance classification maps for the purpose of monitoring and analysing land use/land cover change between 2000 and 2015 for the Emirate of Dubai. The approach was modified by collecting 320 training samples from QuickBird images with a spatial resolution of 0.6 m, as well as carrying out field observations, followed by the application of a 3?×?3 Soble filter, sieving classes, majority/minority analysis, and clump classes of the obtained classification maps. The accuracy assessment showed that the targeted 2000, 2005, 2010 and 2015 classification maps have 88.1252%, 89.0699%, 90.1225% and 96.0965% accuracy, respectively. The results showed that the built-up area increased by 233.721?km² (5.81%) between 2000 and 2005 and continues to increase even up and till the present time. The assessment of changes in the periods 2000–2005 and 2010–2015 confirmed that net vegetation area losses were more pronounced from 2000 to 2005 than from 2010 to 2015, dropping from 47,618 to 40,820?km², respectively. This study is aimed to assist urban planners and decision-makers, as well as research institutes.     

Palaeoproterozoic U–Pb SHRIMP zircon age from basement rocks in Bangladesh: A possible remnant of the Columbia supercontinent

We present new U–Pb SHRIMP zircon geochronological data for basement rocks in Bangladesh, and discuss the relationship with the formation of the Columbia supercontinent. Euhedral zircons from a diorite sample yield a concordia age of 1730 ± 11 Ma, which is interpreted as the crystallization age. The Palaeoproterozoic age of the examined basement rock and the common occurrences of similar 1.7-Ga geologic units in the Central Indian Tectonic Zone and Meghalaya-Shillong Plateau in Indian Shield suggest their apparent continuation. This, together with the occurrence of similar 1.7-Ga geologic units in the Albany-Fraser belt in Australia and East Antarctica, are used to suggest that the basement rocks in Bangladesh formed towards the final stages of the assembly of the Columbia supercontinent.     

A review on mechanism and future perspectives of cadmium-resistant bacteria

Since the last few decades, cadmium anthropocentric sources have been increased drastically. Various chemical and physical approaches for cadmium remediation have been proposed, but these techniques are quite expensive, not healthy for the environment and not efficient at the low concentration of cadmium. Thus, in the last few years, the cadmium removal by biological approaches has received a great interest. Many bacteria can resist against high concentration of cadmium through different mechanisms. The cadmium-resistant bacteria can be grouped into three levels. The main group consists of bacteria which efflux the cadmium from the cells. The bacteria of the other two groups are capable of detoxifying or binding cadmium. The cadA and cadB gene systems are involved in efflux mechanism, and these encode different efflux pump proteins, while the functional groups such as amine, carboxyl, phosphate and hydroxyl facilitate cadmium binding to bacterial surface such as chemisorption. Many enzymes are involved in the detoxifying the cadmium and make the membrane impermeable against cadmium. This paper also reviews the industrial application of cadmium-resistant bacteria and the future perspectives of genetic engineering, bioelectrochemical system, microbial aggregates and biosorption of cadmium by algae.     

Changes in nutritional values induced by butachlor in juvenile diploid and triploid <Emphasis Type="Italic">Clarias gariepinus</Emphasis>

There is a paucity of information about the effects of environmental stressors on nutritional values in fish. This study investigated the effects of the organochlorine pesticide, butachlor, on key indicators of nutritional value in both diploid and triploid African catfish (Clarias gariepinus). Amino acids (AA), fatty acids (FA), and the proximate composition (protein, lipid, moisture, and ash content) in the white muscle of full-sibling juvenile fish were measured following a 21-day exposure to graded butachlor concentrations [mean measured: 26.3, 48.4, and 66.1 µg/L]. No significant differences in AAs, FAs, protein, lipid, moisture, or ash content were observed between unexposed diploid and triploid fish. In diploids, exposure to butachlor significantly altered the concentrations of some of the AAs and FAs, and protein content, when compared to the control group. In triploid fish, however, butachlor treatments had no effect on the AA or proximate composition, but significantly changed the concentration of two individual FAs in the muscle. Butachlor treatments showed fewer changes in the nutritional values of triploid fish. This research is the first to study the nutritional values in any polyploid animals following the exposure to a contaminant.     

Management of saltwater intrusion in coastal aquifers using different wells systems: a case study of the Nile Delta aquifer in Egypt

Hydrogeology Journal - Saltwater intrusion (SWI) is a type of pollution that adversely affects the quality of groundwater in coastal aquifers. The Nile Delta aquifer (NDA) in Egypt contains a large...