Boat and ship engravings at Al Zubarah, Qatar: the dāw exposed?

This is the author accepted manuscript. The final version is available from ArchaeopressOn-going excavations at the site of the 18th–19th century walled town of Al Zubarah, Qatar, have uncovered a number of engravings of seagoing craft etched into the dry plasterwork of buildings within the settlement. The engravings are essentially graffiti, carved into the interiors of rooms without aesthetic reference to the original decorative schema of their settings. The resulting images are of varying sophistication and detail — dependent, no doubt, on the skill and inclination of their executors. While the crudest images are rudimentary outlines of hulls, others show detail that demonstrates the familiarity of their creators with boat construction and type — not surprising in a settlement whose raison d’être was the livings to be made from the sea. This iconographic vestige provides an insight into the types of vessel their creators used and encountered, and allows us to venture our own identifications of them. It also prompts us to reflect on the nature of the relationship between Al Zubarah’s some-time residents and the sea: the vessels depicted are for the most part a mixture of ocean-going types built within the Gulf or western Indian Ocean region. One, however, is of a European naval vessel, perhaps suggesting the shadow of British imperial power in the Gulf. Finally, the process of identification of these watercraft inspires renewed reflection on the word ‘dhow’ and its variants, from both a typological and an etymological perspective; these new reflections are presented at the end of this paper

Alcohol: taking a population perspective

Alcohol consumption is a global phenomenon, as is the resultant health, social and economic harm. The nature of these harms varies with different drinking patterns and with the societal and political responses to the burden of harm; nevertheless, alcohol-related chronic diseases have a major effect on health. Strong evidence exists for the effectiveness of different strategies to minimize this damage and those policies that target price, availability and marketing of alcohol come out best, whereas those using education and information are much less effective. However, these policies can be portrayed as anti-libertarian and so viewing them in the context of alcohol-related harm to those other than the drinker, such as the most vulnerable in society, is important. When this strategy is successful, as in Scotland, it has been possible to pass strong and effective legislation, such as for a minimum unit price for alcohol

Influence of vertical distribution of phytoplankton on remote sensing signal of Case II waters : southern Caspian Sea case study

Reliable monitoring of coastal waters is not possible without using remote sensing data. On the other hand, it is quite difficult to develop remote sensing algorithms that allow one to retrieve water characteristics (like chlorophyll-a concentration) in optically complex coastal and inland waters (called also Case II waters) as the concentrations of optically active substances (phytoplankton, suspended matter, and colored dissolved organic matter) vary independently from each other and the range of variability is often high. Another problem related to developing remote sensing algorithms for retrieving concentrations of optically active substances in such complex waters is vertical distribution of these substances. For example, phytoplankton distribution in the water column is often characterized with maxima just below the surface mixed layer, and some phytoplankton species even have the capability to migrate in the water column and tend to form layers at depths optimal for their growth. Twenty-three field campaigns were performed during the spring-summer period in the coastal waters of the southern Caspian Sea where vertical distribution of phytoplankton was measured by means of chlorophyll-a fluorometer. There results showed that there is usually a chlorophyll-a maximum between 10 and 20 m where the concentration is about one order of magnitude higher than in the top mixed layer. The Hydrolight 5.0 radiative transfer model used to estimate if the vertical distribution of biomass have detectable impact on remote sensing signal in these waters. For that purpose, several stations with distinctly different chlorophyll-a profiles were selected and two simulations for each of those measuring stations was carried out. First the Hydrolight was run with the actual chlorophyll-a vertical distribution profile and second a constant chlorophyll-a value (taken as an average of measured chlorophyll-a in the surface layer) was used in the model simulation. The modelling results show that the “deep” chlorophyll maximum has negligible effect on the remote sensing reflectance spectra. Consequently, there is no need to take into account the vertical distribution of phytoplankton while developing remote sensing algorithms for the Caspian Sea coastal water

Simulations of an OSNR-limited all-optical wavelength conversion scheme

We present simulations of a scheme to perform wavelength conversion of signals that eliminates phase-noise transfer from the pump to the converted signal. Nondegenerate four-wave mixing in a semiconductor optical amplifier is used to convert the signal to a new wavelength; and if an optical comb generator is used as the multiple-pump source, then the signal can be converted without incurring any phase-noise transfer from the pumps. We highlight the capabilities of this scheme by simulating the conversion of 16-QAM signals at 10 Gbaud and showing that errors due to phase-noise accumulation are eliminated thus enabling conversion whose only impairment would be the total additive optical noise