2,485 research outputs found

    Ceramic Architectural Models from the Madaba Plains Region: A Selected Art Historical Analysis

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    Problem Architectural models can be described as small, ceramic, house-shaped structures that come in an often bewildering array of shapes and sizes. They appear all over the ancient Near East, and although evidence shows that they were created as early as the Neolithic period, they seem to have peaked in popularity and proliferation during the Iron Age. A few studies and several typologies have been offered over the years, but none have addressed iconography or artistic motifs as well as shape. Furthermore, no in-depth typology of architectural models within the country of Jordan has been offered. This dissertation explores the symbiotic relationship between art-historical analysis and archaeology by comparing mostly unpublished architectural models and fragments from two sites in Jordan, Tall al-\u27Umayri and Khirbet \u27Ataruz, and paralleling them with the larger corpus of architectural models from surrounding regions. Method Drawing on previous studies and typologies, this study involves a comprehensive description of each object from an art-historical viewpoint. Visual inspection and study of these objects first-hand was placed against a broader picture put forth by publications, focusing on iconography, potential interpretation, and architectural models in general. Positioned within the context of the archaeological setting, this analysis has allowed for suggested interpretations about the iconography, creation, use, and proposed cultic practices of which these objects were part. Results and Conclusions The results of this study have shown that the architectural models and fragments chosen for research were an important part of a thriving cultic life during the Iron Age at both Tall al-\u27Umari and Khirbet \u27Ataruz. The study has also revealed a busy architectural model industry that is demonstrated by the varying styles, ability levels, and cultural influences found within each object. By analyzing the formal artistic qualities of each object within the archaeological context, the importance that these objects had upon the lives of those who created them as well as the patrons who utilized and worshiped through them has been demonstrated. The analysis of fragments along with more complete forms has also allowed for a greater picture of distribution and has revealed that these objects were more common than previously thought. The compilation of the data gathered in this study called for a new type of typology to be created in order to unify and streamline research for the architectural models of Transjordan. The creation of the Madaba Plains Architectural Model Typology allows for a more streamlined categorization based on type and ornamentation and is easily adaptable as new data comes to light

    Investigation of single crystal ferrite thin films

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    Materials suitable for use in magnetic bubble domain memories were developed for aerospace applications. Practical techniques for the preparation of such materials in forms required for fabrication of computer memory devices were considered. The materials studied were epitaxial films of various compositions of the gallium-substituted yttrium gadolinium iron garnet system. The major emphasis was to determine their bubble properties and the conditions necessary for growing uncracked, high quality films

    Opisthorchiasis-associated biliary stones: light and scanning electron microscopic study

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    Aim: Biliary stones are frequently encountered in areas endemic for opisthorchiasis in Thailand. The present study was to describe the prevalence and pathogenesis of these stones. Methods: Gallstones and/or common bile duct stones and bile specimens from 113 consecutive cholecystectomies were included. Bile samples, including sludge and/or microcalculi, were examined for Opisthorchis viverrini eggs, calcium and bilirubin. The stones were also processed for scanning electron microscopic (SEM) study. Results: Of the 113 cases, 82 had pigment stones, while one had cholesterol stones. The other 30 cases had no stones. Most of the stone cases (76%, 63/83) had multiple stones, while the remainder had a single stone. Stones were more frequently observed in females. Bile examination was positive for O. viverrini eggs in 50% of the cases studied. Aggregates of calcium bilirubinate precipitates were observed in all cases with sludge. Deposition of calcium bilirubinate on the eggshell was visualized by special staining. A SEM study demonstrated the presence of the parasite eggs in the stones. Numerous crystals, morphologically consistent with calcium derivatives and cholesterol precipitates, were seen. Conclusion: Northeast Thailand has a high prevalence of pigment stones, as observed at the cholecystectomy, and liver fluke infestation seems involved in the pathogenesis of stone formation. Copyrigh

    Chondrites as samples of differentiated planetesimals

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    Chondritic meteorites are unmelted and variably metamorphosed aggregates of the earliest solids of the solar system. The variety of metamorphic textures in chondrites motivated the “onion shell” model in which chondrites originated at varying depths within a parent body heated primarily by the short-lived radioisotope 26Al, with the highest metamorphic grade originating nearest the center. Allende and a few other chondrites possess a unidirectional magnetization that can be best explained by a core dynamo on their parent body, indicating internal melting and differentiation. Here we show that a parent body that accreted to >~200 km in radius by ~ 1.5 Ma after the formation of calcium–aluminum-rich inclusions (CAIs) would have a differentiated interior, and ongoing accretion would add a solid undifferentiated crust overlying a differentiated interior, consistent with formational and evolutionary constraints inferred for the CV parent body. This body could have produced a magnetic field lasting more than 10 Ma. This hypothesis represents a new model for the origin of some chondrites, presenting them as the unprocessed crusts of internally differentiated early planetesimals. Such bodies may exist in the asteroid belt today; the shapes and masses of the two largest asteroids, 1 Ceres and 2 Pallas, can be consistent with differentiated interiors, conceivably with small iron cores with hydrated silicate or ice–silicate mantles, covered with undifferentiated crusts.National Science Foundation (U.S.) (NSF Astronomy CAREER grant)Mitsui & Co. (U.S.A.), Inc. ( Mitsui Career Development Professorship)United States. National Aeronautics and Space Administration (NASA Origins grant)Massachusetts Institute of Technology (Victor P. Starr Career Development Professorship)United States. National Aeronautics and Space Administration (NASA/Dawn co-investigator grant

    Nitrous oxide in fresh water systems: An estimate for the yield of atmospheric N2O associated with disposal of human waste

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    The N2O content of waters in the Potomac and Merrimack Rivers was measured on a number of occasions over the period April to July 1977. The concentrations of dissolved N2O exceeded those which would apply in equilibrium with air by factors ranging from about 46 in the Potomac to 1.2 in the Merrimack. Highest concentrations of dissolved N2O were associated with sewage discharges from the vicinity of Washington, D. C., and analysis indicates a relatively high yield, 1.3 to 11%, for prompt conversion of waste nitrogen to N2O. Measurements of dissolved N2O in fresh water ponds near Boston demonstrated that aquatic systems provide both strong sources and sinks for atmospheric N2O

    Ross operation in children and young adults: the Alder Hey case series

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    BACKGROUND: The ideal prosthesis for aortic valve replacement in children and young adults has not been found yet. In recent years there has been a renewed interest in the replacement of aortic valve with the pulmonary autograft owing to its advantages of lack of anticoagulation, potential for growth and excellent haemodynamic performance. The purpose of this study was to review our institutional experience at Alder Hey hospital with the Ross procedure in children and young adults. METHODS: From November 1996 to September 2003, 38 patients (mean age, 13.1 ± 5.7 years) underwent the Ross procedure for various aortic valve diseases using the root replacement technique. Clinical and echocardiographic follow-up was performed early (within 30 days), 3 to 6 months, and yearly after surgery. Medical records of all patients were reviewed retrospectively. RESULTS: There was 1 perioperative death. The patients were followed-up for a median interval of 36 months and up to 7 years. One patient died 3 years after surgery secondary to ventricular arrhythmia with overall mortality of 5.3%. Actuarial survival at 7 years was 94 ± 2.5% and there was 100% freedom from reoperation for autograft valve dysfunction or any other cause. Balloon dilatation was required in 2 patients for pulmonary homograft stenosis. The haemodynamics at the latest follow-up were also similar to those at the time of discharge after surgery. There was no progression in the degree of aortic regurgitation for 11 patients with trivial and 3 with mild regurgitation. CONCLUSION: Our experience demonstrates that Ross operation is an attractive option for aortic valve replacement in children and young adults. Not only can the operation be accomplished with a low operative risk but the valve function stays normal over a long period of time with minimal alteration in lifestyle and no need for repeated operations to replace the valve as a result of somatic growth of the children

    Escape of the martian protoatmosphere and initial water inventory

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    Latest research in planet formation indicate that Mars formed within a few million years (Myr) and remained a planetary embryo that never grew to a more massive planet. It can also be expected from dynamical models, that most of Mars' building blocks consisted of material that formed in orbital locations just beyond the ice line which could have contained ~0.1-0.2 wt. % of H2O. By using these constraints, we estimate the nebula-captured and catastrophically outgassed volatile contents during the solidification of Mars' magma ocean and apply a hydrodynamic upper atmosphere model for the study of the soft X-ray and extreme ultraviolet (XUV) driven thermal escape of the martian protoatmosphere during the early active epoch of the young Sun. The amount of gas that has been captured from the protoplanetary disk into the planetary atmosphere is calculated by solving the hydrostatic structure equations in the protoplanetary nebula. Depending on nebular properties such as the dust grain depletion factor, planetesimal accretion rates and luminosities, hydrogen envelopes with masses >=3x10^{19} g to <=6.5x10^{22} g could have been captured from the nebula around early Mars. Depending of the before mentioned parameters, due to the planets low gravity and a solar XUV flux that was ~100 times stronger compared to the present value, our results indicate that early Mars would have lost its nebular captured hydrogen envelope after the nebula gas evaporated, during a fast period of ~0.1-7.5 Myr. After the solidification of early Mars' magma ocean, catastrophically outgassed volatiles with the amount of ~50-250 bar H2O and ~10-55 bar CO2 could have been lost during ~0.4-12 Myr, if the impact related energy flux of large planetesimals and small embryos to the planet's surface lasted long enough, that the steam atmosphere could have been prevented from condensing. If this was not the case... (continued)Comment: 47 pages, 10 figures, 3 tables, submitted to PS

    Making judgements about students making work : lecturers’ assessment practices in art and design.

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    This research study explores the assessment practices in two higher education art and design departments. The key aim of this research was to explore art and design studio assessment practices as lived by and experienced by art and design lecturers. This work draws on two bodies of pre existing research. Firstly this study adopted innovative methodological approaches that have been employed to good effect to explore assessment in text based subjects (think aloud) and moderation mark agreement (observation). Secondly the study builds on existing research into the assessment of creative practice. By applying thinking aloud methodologies into a creative practice assessment context the authors seek to illuminate the ‘in practice’ rather than espoused assessment approaches adopted. The analysis suggests that lecturers in the study employed three macro conceptions of quality to support the judgement process. These were; the demonstration of significant learning over time, the demonstration of effective studentship and the presentation of meaningful art/design work

    A Self-Consistent Model of the Circumstellar Debris Created by a Giant Hypervelocity Impact in the HD172555 System

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    Spectral modeling of the large infrared excess in the Spitzer IRS spectra of HD 172555 suggests that there is more than 10^19 kg of sub-micron dust in the system. Using physical arguments and constraints from observations, we rule out the possibility of the infrared excess being created by a magma ocean planet or a circumplanetary disk or torus. We show that the infrared excess is consistent with a circumstellar debris disk or torus, located at approximately 6 AU, that was created by a planetary scale hypervelocity impact. We find that radiation pressure should remove submicron dust from the debris disk in less than one year. However, the system's mid-infrared photometric flux, dominated by submicron grains, has been stable within 4 percent over the last 27 years, from IRAS (1983) to WISE (2010). Our new spectral modeling work and calculations of the radiation pressure on fine dust in HD 172555 provide a self-consistent explanation for this apparent contradiction. We also explore the unconfirmed claim that 10^47 molecules of SiO vapor are needed to explain an emission feature at 8 um in the Spitzer IRS spectrum of HD 172555. We find that unless there are 10^48 atoms or 0.05 Earth masses of atomic Si and O vapor in the system, SiO vapor should be destroyed by photo-dissociation in less than 0.2 years. We argue that a second plausible explanation for the 8 um feature can be emission from solid SiO, which naturally occurs in submicron silicate "smokes" created by quickly condensing vaporized silicate.Comment: Accepted to the Astrophysical Journa
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