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As a technique for non-destructive materials analysis, computed tomography (CT) has been especially useful for studying the dependence of the structure of ceramics on manufacturing processes. CT also has been used for characterizing the lithology of reservoir cores while they are still contained in preservation material or a core barrel.
The parameter measured by CT is the X-ray attenuation coefficient, which is a function of both material density and material composition.
We present new results from a number of deep radio polarization surveys of the Magellanic Clouds at 2.3 GHz, 4.75 GHz and 8.55 GHz. Extended linearly polarized radio emission has been found at 2.3 and 4.75 GHz from both galaxies.
Increased marine 14C reservoir ages from the surface water of the North Atlantic are documented for the Younger Dryas period. We use terrestrial and marine AMS 14C dates from the time of deposition of the Icelandic Vedde Ash to examine the marine 14C reservoir age. This changed from its modem North Atlantic value of ca. 400 yr to ca. 700 yr during the Younger Dryas climatic event. The increased marine reservoir age has implications for both comparing climatic time series dated by 14C and understanding palaeoceanographic changes that generated the increase.
Since the last General Assembly in Patras, Greece, we have held three meetings of the Working Group. The 10th Meeting was held in Mzkheta, the ancient capital of Georgia, USSR, hosted by their Academy of Sciences on April 3-7, 1984. All members except one, who was represented by a member of his Task Group, were present at the very productive meeting.
During past three years from 1982 to 1984 we saw the further progress in the planets and satellites research by the space and ground-based technique, in the analysis and interpretation of the observational data. Inspite of some decrease of the activity in the planetary spacecrafts launches during this period (except of two Soviet missions to Venus) many important scientific results were obtained from the continued reduction and analysis of the measurements which were performed by Mariner 10 (Mercury), Pioneer Venus, Venera 13 and 14, Viking (Mars), Pioneer 10 and 11, and Voyager 1 and 2.
We present preliminary results from a number of deep radio polarization surveys being made of the Magellanic Clouds at 2.3 GHz, 4.75 GHz and 8.55 GHz. Extended and linearly polarized radio emission has been found at 2.3 and 4.75 GHz from both the Large Magellanic Cloud (LMC) and the Small Magellanic Cloud (SMC). However, as the analysis of these data is not yet complete we present only some of the 4.75 GHz results at this time.
The Parkes radio telescope was commissioned in 1961, with an anticipated operational life of 15 years. Twentyfive years later the telescope has been refurbished with the aim of extending its life yet another decade or two. A major undertaking has been the complete replacement of the drive and control System. This presentation outlines the main features of the new System and its effect on the observing facilities offered at the observatory.
During 1990 we surveyed the southern sky using a multi-beam receiver at frequencies of 4850 and 843 MHz. The half-power beamwidths were 4 and 25 arcmin respectively. The finished surveys cover the declination range between +10 and −90 degrees declination, essentially complete in right ascension, an area of 7.30 steradians. Preliminary analysis of the 4850 MHz data indicates that we will achieve a five sigma flux density limit of about 30 mJy. We estimate that we will find between 80 000 and 90 000 new sources above this limit. This is a revised version of the paper presented at the Regional Meeting by the first four authors; the surveys now have been completed.
In a letter of exhortation on the ascetic life addressed to monks of the Bierzo region in north-western Spain in the late seventh century, the local spiritual leader Valerius invoked the saintly example of a ‘fragile woman’. Her name was Egeria, who, at the time when ‘the luminous shining light of our holy religion was finally kindled after long delay in this region of the west’, had fearlessly embarked on a monumental journey encompassing the ‘whole world’. The object of Egeria’s God-inspired Wanderlust had been the biblical holy places of Old and New Testaments, as well as the monastic heartland of Egypt, through all of which Valerius found in her a model of tireless zeal and thanksgiving to parade before his correspondents. It was especially her intrepid ascent to the summits of holy mountains which characterized this exceptional woman as a paragon of spiritual endeavour, and Valerius’ monks were to be encouraged, if not to climb every mountain, at least to reach their own heights of discipline and self-denial, to ‘blush’ at the fortitude of one who ‘transformed the weakness of her sex into an iron strength’.
On 27 February 380, the emperor Theodosius – newly elevated the previous year to take control of the East amid the political and military turmoil unleashed by the debacle at Adrianople -addressed an edict from his current headquarters at Thessalonica to the people of Constantinople. The text famously proclaimed the religion to be followed by ‘all the peoples’ who fell under his rule as that handed down at Rome from the apostle Peter, now maintained by the pontifex Damasus and bishop Peter of Alexandria, ‘that is,… we should believe in the single godhead of Father, Son and Holy Spirit, in equal majesty and holy trinity’. Those who subscribed to this doctrine, Theodosius ordered, were to ‘embrace the name of Catholic Christians’, while all the rest were branded heretics, whose places of assembly were denied the name of churches, and who would be smitten ‘first by divine vengeance, and afterwards by the retribution of our own punishment, which we shall enact in accordance with the judgement of Heaven’.
The 100 m telescope was used to complete the northern sky survey started at Jodrell Bank. The survey aimed at reaching the confusion limit of the telescope. Zero levels are consistent within ± 3 K, and scale errors are less than 10%. The survey will be published in the form of maps; a machine readable version is also available.
Gamma-ray burst host galaxies are deficient in molecular gas, and show anomalous metal-poor regions close to GRB positions. Using recent Australia Telescope Compact Array (ATCA) Hi observations we show that they have substantial atomic gas reservoirs. This suggests that star formation in these galaxies may be fuelled by recent inflow of metal-poor atomic gas. While this process is debated, it can happen in low-metallicity gas near the onset of star formation because gas cooling (necessary for star formation) is faster than the Hi-to-H2 conversion.
A geological reconnaissance of the Beni Ulid — Wadi Merdum region of the pre-desert of Tripolitania shows that at least twenty, stratigraphically distinct geomorphic events can be recognised from field exposures, field mapping and the analysis of Spacelab metric camera photography. The earliest events are provisionally attributed to the early Cenozoic and include uplift, tilting, faulting, the formation of karstic and karst-tectonic landforms, and erosion by meandering river systems. Some of these valleys were infilled with lava flows from the south-south-west in the ?late Palaeocene/early Eocene. Re-excavation of the ancient landscape by rivers followed. Pleistocene deposits of powerful, often braided rivers occur in the wadi floor. The wadi sides are clothed in complex sequences of alluvial fans, screes, windblown, waterlain and anthropogenic deposits, sometimes with weathering horizons and calcretes of uncertain stratigraphic significance. The plateaux contain large alluvial basins, palaeosols, soils and weathering horizons of uncertain age. Accelerated soil erosion caused by human activity appears to have been important in the area — slope deposits of scree and midden between 4 and 8 metres in thickness have accumulated beneath one gasr during a 500 year period. The most recent deposits identified are complex aeolian deposits at the wadi edge and the interdigitating series of floodloams and aeolian sands on the wadi floors.
Digital image data from the Landsat satellite Multispectral scanner have been analysed using a Dipex Image Processor. The image data were classified by a clustering algorithm to produce a thematic map for trial use in areas of archaeological interest. The archaeological, pedological, geomorphic and geological importance of these new data are discussed in the context of ground data obtained during the UNESCO April 1984 field season.
The description and analysis of particle size distributions using log skew Laplace distributions is a new technique designed to overcome various mathematical and computational problems associated with other approaches. This paper presents an application of the method. In particular, it describes fitting log skew Laplace distributions to modern and ancient shoreline sands from Lepcis Magna (near Horns), Tripolitania, with the purpose of discriminating between modern environments and so classifying the ancient samples. Satisfactory discrimination was not always achieved between some of the modern ‘calibration’ shoreline sand samples of known provenance — possibly as a result of the presence of multimodal distributions. One layer in the harbour-infill sequence, previously of unknown provenance, was shown to have collected at, or close to, an ancient shoreline which developed within the ancient harbour. The majority of the ‘ancient’ samples of unknown depositional environments which were excavated from exposures in the Romano-Libyan harbour-infill sands, were shown by this analysis to be of neither beach nor aeolian origin. This conclusion supports field observations which suggested that the greater part of the harbour-infill sequence represented reworked dune palaeosols, developing dune soils and fluvial and lagoonal facies.
To report the design and baseline results of a rewards-based incentive to promote purchase of fruit and vegetables by lower-income households.
A four-phase randomized trial with wait-listed controls. In a pilot study, despite inadequate study coupon use, purchases of fresh fruit (but not vegetables) increased, but with little maintenance. In the present study, credits on the study store gift card replace paper coupons and a tapering phase is added. The primary outcome is the number of servings of fresh and frozen fruit and vegetables purchased per week.
A large full-service supermarket located in a predominantly minority community in Philadelphia, Pennsylvania, USA.
Fifty-eight households, with at least one child living in the home.
During the baseline period, households purchased an average of 3·7 servings of fresh vegetables and an average of less than 1 serving of frozen vegetables per week. Households purchased an average of 1·9 servings of fresh fruit per week, with little to no frozen fruit purchases. Overall, the range of fresh and frozen produce purchased during this pre-intervention period was limited.
At baseline, produce purchases were small and of limited variety. The study will contribute to understanding the impact of financial incentives on increasing the purchases of healthier foods by lower-income populations.