Imaging of hydrothermal altered zones in Wadi Al-Bana, in southern Yemen, using remote sensing techniques and very low frequency–electromagnetic data

© 2019, Saudi Society for Geosciences. Economic mineralization and hydrothermally altered zones are areas of great economic interests. This study focusses on hydrothermal altered zones of high mineralization potentials in Wadi Al-Bana, in southern Yemen. An azimuthal very low frequency–electromagnetic (AVLF-EM) data acquisition was conducted in search for mineralization in the study area. The study integrated observations from geophysical field data with others extracted from object-oriented principal component analysis (PCA) to better map and understand mineralization in the investigated area. This technique was applied to two data sets, ASTER and Landsat 8 Operational Land Imager (OLI) imagery. The results of PCA revealed high accuracy in detecting alteration minerals and for mapping zones of high concentration of these minerals. The PCA-based distribution of selected alteration zones correlated spatially with high conductivity anomalies in the subsurface that were detected by VLF measurements. Finally, a GIS model was built and successfully utilized to categorize the resulted altered zones, into three levels. [Figure not available: see fulltext.]

What determines cell size?

AbstractFirst paragraph (this article has no abstract) For well over 100 years, cell biologists have been wondering what determines the size of cells. In modern times, we know all of the molecules that control the cell cycle and cell division, but we still do not understand how cell size is determined. To check whether modern cell biology has made any inroads on this age-old question, BMC Biology asked several heavyweights in the field to tell us how they think cell size is controlled, drawing on a range of different cell types. The essays in this collection address two related questions - why does cell size matter, and how do cells control it

Large‐magnitude fissure eruptions in Iceland: source characterisation.

The British Geological Survey and the Met Office together with government departments, agencies and academic partners across the UK and in Iceland are engaged in a programme of work that aims to ensure that plans are in place in Iceland, the UK and the rest of Europe to facilitate a coordinated and timely response to future eruptions that occur in Iceland. As a consequence of the eruption of the Eyjafjallajökull volcano in 2010, Professor Sir John Beddington appointed a ‘Scientific Advisory Group in Emergencies’ (SAGE) which met several times during the eruption. One of the tasks of the SAGE was to consider potential future eruption scenarios that might affect the UK and as a result, volcanic eruptions were included for the first time in the UK National Risk Register (NRR). One of the scenarios adopted in the NRR (https://www.gov.uk/government/publications/national‐risk‐register‐of‐civil‐emergencies) is based on the 1783‐4 fissure eruption of Grimsvötn volcano, commonly known as the ‘Laki eruption’. The BGS was contracted to characterise source parameters and their uncertainties to enable further modelling of a Laki eruption scenario, a critical step towards better understanding the possible impacts of such an eruption. This report presents the outcomes of a meeting and expert elicitation held under contract to the Cabinet Office in May 2012. A multidisciplinary expert group with specialist knowledge of this particular type of eruption, volcanic degassing, remote sensing of gases and aerosols, atmospheric processes and dispersion modelling was nominated to take part, along with a few experts on the health and environmental impacts of volcanic eruptions to provide guidance on their modelling requirements. The elicitation was run by Professor Willy Aspinall. It is hoped that the very short process that led to this report was nevertheless sufficient to stimulate valuable scientific discussion, to prompt planning initiatives and to motivate relevant research proposals. This report acts as a multidisciplinary resource with key research papers and the outcomes of the meeting presented as well as the elicited source parameters. Areas where scientific understanding is limited or is still emerging are highlighted here as ‘knowledge gaps’ and research to tackle these gaps is recommended. Planning by government departments, research institutes and others is underway and can also be guided by the contents this report. It is suggested that consideration is given as to how scientific inputs should best be delivered in any future volcanic emergency, in the light of recent experiences