Overview of LIMEX'87 ice observations

Ice observations, results, and conclusions are summarized for the March 1987 Labrador Ice Margin Experiment (LIMEX'87), an international oceanographic study conducted in the pack ice of the Grand Banks area off the coast of Newfoundland. Included are the ice extent, flow size and thickness, ice kinematics and rheology, ice microwave properties, oceanic properties under the ice, and penetration of swell into the ice     

Cytochrome P450 and dependent activities in unexposed and PAH-exposed terrestrial annelids

The cytochrome P450 system of the oligochaetes Eisenia f. fetida (tiger worm) and Enchytraeus crypticus (pot worm) was analysed using ethoxy-, pentoxy- and benzoxyresorufin as substrates for monooxygenase activity. Whole body microsomes of the earthworm E.f. fetida displayed PentROD activity in the range from 0.26 to 1.05 pmol mg protein-1 min-1 and BenzROD activity in the range from 0.14 to 0.30 pmol mg protein-1 min-1. Exposure of the animals for up to four weeks to 100 mg fluoranthene or benzo[a]pyrene kg-1 soil (dry weight) did not induce significant changes in the activity of these monooxygenases. In E. crypticus EROD activity was in the range from 2.10 to 6.18 pmol mg protein-1 min-1 and PentROD activity in the range from 1.75 to 4.78 pmol mg protein-1 min-1. Short-term exposure to BaP by feeding reduced the EROD activity significantly by 45%, but did not effect PentROD activity. After long-term (8 weeks) exposure to BaP in the agar-agar medium EROD activity was not changed but PentROD had decreased to zero. In both species cytochrome P420 and NADPH-cytochrome C reductase activity were present. In E.f. fetida microsomes are associated with the giant haemoglobin. Both can be separated by gel filtration on a Sepharose B2 column or by hydrophobic interaction chromatography after solubilisation with cholate. NADPH-cytochrome C reductase elutes together with haemoglobin. Cytochrome P420 is eluted with Emulgen 911 and can be further purified by ion exchange chromatography using HA-Ultrogel. By SDS-PAGE of the purified microsomal proteins three protein bands are visualised in the range of cytochrome P450 displaying an apparent molecular mass of 54, 56 and 58 kDa. Only the 54-kDa protein interacts weakly with perch (Perca fluviatilis) CYP1A antibodies, while two proteins with an apparent molecular mass of 65 and 71 kDa give a strong antibody signal.     

The atomic age challenge to steel

Some months ago the submarine Nautilus was in dock for refueling. It had traveled 60,000 miles, but the total uranium used would make a lump smaller than a light bulb. This is only one example that the Atomic Age is here with us, now! How and where does this incredible Atomic Age challenge the first and greatest of America’s basic industries?     

On the Mediation of Everything: ICA Presidential Address 2008

As our field moves beyond the traditional dualism of mass and interpersonal forms of communication to encompass new, interactive, networked forms of communication whose influence may be traced across multiple spheres of modern life, it is commonly claimed that "everything is mediated" and that this represents a historically significant change. This article inquires into these rhetorically grand claims: first, noting the parallels with other processes of mediation (e.g., language, money, and myths); second, raising questions of value since, unlike for other forms of mediation, the media's role is typically construed as negative rather than positive; and third, observing that the difficulties of translating "mediation" into a range of languages reveals some conceptual confusions. As a step toward clarification, I contrast the terms "mediation" and "mediatization," these roughly mapping onto situational and historical influences, conceived primarily at micro- and macrolevels of analysis, respectively. I then argue for a broad conception of mediation that encompasses those processes variously referred to as "mediatization,""mediazation," or "medialization." The analysis is illustrated by unpacking the claim that "childhood is mediated," before concluding that distinct aspects of the concept of mediation invite communication scholars to attend to the specific empirical, historical, and political implications of the claim that "everything is mediated."     

Discrimination of sea ice in the Labrador marginal ice zone from synthetic aperture radar image texture

This study addresses the modelling of synthetic aperture radar (SAR) image texture for sea ice scenes in the Labrador marginal ice zone (MIZ). The image texture of distributed scatterers contains a substantial component relating to the imaging system as well as information about the scene itself. Theory shows that the image autocorrelation function (ACF) may be analysed to separate system contributions from scene contributions under certain conditions. The main theses of the study are: (i) SAR intensity images of sea ice are spatially nonGaussian; and (ii) the predominant types and forms of MIZ sea ice may be discriminated based upon ACF model parameters. Experimental results indicate that the model provides an excellent fit to the measured ACFs. The image texture was found to be a strong function of the form of the sea ice as well as its type. For a given type, the various forms could be discriminated through a single SAR channel. For full discrimination of all types and forms observed, a two-channel combination was necessary: XHV CHH or XHV CHV.     

Strategies of parental regulation in the media-rich home

This paper investigates practices of domestic regulation of media within the family, focusing on parental attempts to manage children’s access to and use of new media. Theoretically, the paper seeks to integrate the specific literature on domestic rules and regulation of media use with the broader literature on the rules and roles in social situations, arguing that parental strategies in relation to domestic media reveal both the enactment of and the negotiations over the typically informal and implicit rules and roles in family life. These issues are explored using data from two surveys: (1) the ‘Young People, New Media’ project surveyed 1300 children and their parents, examining the social, relational and contextual factors that shape the ways in which families develop rules for managing the introduction of the personal computer and the multiplication of television sets, among other new media changes, in the home; (2) the ‘UK Children Go Online’ project surveyed 1500 children and their parents, updating the picture by examining the introduction of the Internet into the family home. On the basis of these data, it is argued that despite the ‘newness’ of media as they successively arrive in the home, there are considerable consistencies over time in the responses of families, it being the slow-to-change relations between parents and children that shape patterns of domestic regulation and use.     

Airborne C-band SAR measurements of wet snow-covered areas

Using polarimetric synthetic aperture radar (SAR) data at C-band, the optimum polarization and range incidence angles for the classification of land covers found in the James Bay area, P.Q., Canada-open areas, lakes ice, and forests, all covered with wet snow-have been examined. The separability between classes shows that they can be classified by a single polarization. For &thetas;<30°, the overall classification accuracies were 97.1, 98, and 90.8% from HH-, cross, and VV-polarizations alone, respectively. They were greater than 99% for all polarizations at &thetas;>30°. However, the polarimetric parameters were not suitable for classification     

A comparison of Schottky barrier position-sensitive detectors as a function of light wavelength

Position-sensitive detectors (PSDs), are single continuous optical sensors that utilize the lateral photovoltaic effect to produce an electrical output that varies linearly with light spot position. This work reports further on the results from Schottky barrier PSDs fabricated from thin films of tantalum, titanium, and aluminum. The optimal thickness of the Schottky metals was determined, trading off light transmissivity and proper Schottky barrier formation. The objective of this work was to determine if devices performed particularly well or poorly under certain light sources and, if so, at what thickness of film. Each device has been tested in one dimension under 5 mW of red laser light, focused broad-band light, as well as filtered red, green, and blue light. It was found that all devices generally responded well to the filtered red light and worst under the green light source. The extent to which this is true depends on the Schottky metal used and its thickness. It was also found that the detector response changed over time. Most interestingly, the tantalum Schottky barrier devices either improved or remained the same while the titanium devices deteriorated noticeably.     

A wide-band acoustooptic TE-TM mode converter using a doubly confined structure

Bandwidth limitations of collinear acoustooptic TE-TM mode converters have been overcome by a method in which the optical and surface acoustic waves have been interacted in a doubly confined waveguide structure. A 5 percent bandwidth centered at 550 MHz and a conversion efficiency of 50 percent at a total acoustic input power of less than 1 mW have been obtained withY-cut LiNbO3. It is found that the power transfer efficiency does not degrade significantly when the phase mismatch increases.