Semiregular variables in the solar neighbourhood

Period–luminosity sequences have been shown to exist among the semiregular variables (SRVs) in the Magellanic Clouds, the bulge of the Milky Way galaxy and elsewhere. Using modern-period and revised Hipparcos parallax data, this paper demonstrates that they also appear among the M giant SRVs of the solar neighbourhood. Their distribution in the   K , log  P   diagram resembles that of Bulge stars more closely than those in the Magellanic Clouds. The prevalence of mass-loss among local M-type SRVs and its dependence on period and spectral subtype are also discussed.   K −[12]  , a measure of circumstellar dust emission, increases clearly with V amplitude, M giant subtype and  log  P   .     

Legal aspects of development on dolomite land in South Africa

 Dolomite rock formations underlie large areas of the Gauteng, North, North-West and Mpumalanga Provinces in South Africa. Sinkholes, subsidences and dolines that may form at any place and at any time on these formations pose a threat to the properties and lives of thousands of people who live and work there. Since much urban, industrial and mining development has taken place in these areas, and the demand for housing development is on the increase, the risk of surface damage must be minimized by means of proper site investigations, hazard and risk evaluation and selection of appropriate development. The legal aspects pertaining to development on dolomite land in South Africa and the requirements for geotechnical investigations as outlined in the various ordinances and acts are reviewed here. Received: 15 September 1996 · Accepted: 12 May 1998     

The Alaska Wrangell Arc: ~30 Ma of subduction‐related magmatism along a still active arc‐transform junction

The Oligocene to Present Wrangell Volcanic Belt (WVB) extends for ~500 km across south‐central Alaska (USA) into Canada at a volcanic arc‐transform junction. Previously, geochemistry documented mantle wedge and slab‐edge melting in <12 Ma WVB volcanic rocks; new geochemistry shows that the same processes characterized ~18–30 Ma WVB magmatism in Alaska. New ⁴⁰Ar/³⁹Ar ages demonstrate that WVB magmatism in Alaska initiated at ~30 Ma due to flat‐slab subduction of the Yakutat microplate and that the dextral Totschunda fault was active at this time. Our results, together with prior studies, show that Alaskan WVB magmatism occurred chiefly due to subduction and should be considered a volcanic arc (e.g. the Wrangell Arc). The WVB provides a long‐term geological record of subduction, strike‐slip and magmatism. Slab‐edge upwelling, flat‐slab defocused fluid‐flux and faults acting as magma conduits are likely responsible for the exceptionally large volcanoes and high eruption rates of the Wrangell Arc.     

Biofuel scenarios in a water perspective: The global blue and green water footprint of road transport in 2030

Concerns over energy security and climate change stimulate developments towards renewable energy. Transport is expected to switch from fossil fuel use to the use of fuel mixtures with a larger fraction of biofuels, e.g. bio-ethanol and biodiesel. Growing biomass for biofuels requires water, a scarce resource. Existing scenarios on freshwater use usually consider changes in food and livestock production, and industrial and domestic activities. This research assesses global water use changes related to increasing biofuel use for road transport in 2030 and evaluates the potential contribution to water scarcity. To investigate water demand changes related to a transition to biofuels in road transport, the study combines data from water footprint (WF) analyses with information from the IEA APS energy scenario for 2030. It includes first-generation biofuels, bio-ethanol from sugar cane, sugar beet, sweet sorghum, wheat and maize, and biodiesel from soybean, rapeseed, jatropha and oil palm. Under the IEA APS scenario, the global biofuel WF will increase more than tenfold in the period 2005–2030. The USA, China and Brazil together will contribute half of the global biofuel WF. In many countries, blue biofuel WFs significantly contribute to blue water scarcity. The research provides a first exploration of the potential contribution of transport biofuel use to blue water scarcity. In 2030, the global blue biofuel WF might have grown to 5.5% of the totally available blue water for humans, causing extra pressure on fresh water resources. When biofuel use continues to expand after 2030, countries should therefore consider the water factor when investigating the extent to which biofuels can satisfy future transport energy demand.