1,916 research outputs found

    Graduate Education in Airport Administration: Preparing Airport Managers for the 21st Century

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    Growing numbers of students pursuing management careers in aviation are seeking graduate degrees to prepare for the complex and evolving challenges in the aviation industry. This study questioned members of the American Association of Airport Executives (AAAE) about their profession and the appropriateness of current education opportunities in aviation administration. The purpose of this study was to identify the knowledge and skills that the next generation of airport administrators will need to effectively contend with the new industrial environment

    GENESIS OF DONGPING GOLD-TELLURIDE DEPOSIT BASED ON GEOCHEMICAL CHARACTERISTICS OF FLUIDS, 40Ar/39Ar DATING, STABLE AND RADIOGENIC ISOTOPES (NORTH CHINA)

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    The Dongping goldfield is located within the Shuiquangou alkaline complex of the western Yanshan Mountains of Hebei Province, on the northern margin of the North China Craton. It is one of the largest gold deposits in China, with a planned gold production of 2.57 tons annually over a lifespan of 12 years. The Dongping gold deposit is enriched in the elements Au, Te, Ag, Pb, Bi, Sb and As. Most of the gold is present in the telluride minerals calaverite (43% Au, 38% Ag) and petzite (23% Au, 46% Ag). Gold mineralization is hosted mainly by K-feldspar-quartz stockworks, veins and disseminated sulfides. The deposit contains three ore types that are distinguished by their mineral associations: vein quartz gold, telluride gold, and disseminated gold. The paragenesis of the ores exhibits three distinct hydrothermal stages, of which the second one was the main ore-enrichment stage. The ore-related 40Ar/39Ar ages determined on K-feldspar samples indicate two episodes of gold mineralization, at 154.89 ± 0.70 Ma and 176.93 ± 4.66 Ma. The gold mineralization ages thus postdate the Devonian-age granite intrusion but overlap possible JurassicCretaceous magmatic activity. The homogenization temperatures of the majority of inclusions range from 120 to 240°C and from 240 to 400°C. The inclusions in quartz veins are CO2-rich and characterized by low salinity (average 6.0–8.8 wt% NaCl eq.). The laser Raman spectrum of the inclusions shows that the fluid compositions are dominantly waterrich but also contain CO2. The hydrogen isotope compositions (δ2H) of the fluid inclusions range from ‒100.3 to ‒66.5 ‰, and the calculated oxygen isotope compositions (δ18O) for source fluids range from ‒0.3 to +6.9 ‰ "Standard Mean Ocean Water" (SMOW). These values indicate that the ore-forming fluid came from a deep magmatic hydrothermal system, with involvement of meteoric water and possibly water affected by organic matter. The sulphur isotope compositions (δ34S) of pyrite are mainly from ‒0.3 to ‒13.6 ‰ Vienna Cañon Diablo Troilite (VCDT), suggesting homogeneity of sulphur in the magmatic source with subsequent fractionation under relatively oxidizing conditions in ore-bearing quartz veins. The relationship of δ2HH2O to 87Sr/86Sr indicates that the fluid inclusions and host granitoid rocks were influenced by mixing of magmatic and meteoric waters. Key words: Chongli county; Dongping deposit; 40Ar/39Ar dating; stable and radiogenic isotopes; ore-forming fluids; gold deposit; North Chin

    Comparison between two mobile absolute gravimeters: optical versus atomic interferometers

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    We report a comparison between two absolute gravimeters: the LNE-SYRTE cold atoms gravimeter and FG5#220 of Leibniz Universit\"at of Hannover. They rely on different principles of operation: atomic and optical interferometry. Both are movable which enabled them to participated to the last International Comparison of Absolute Gravimeters (ICAG'09) at BIPM. Immediately after, their bilateral comparison took place in the LNE watt balance laboratory and showed an agreement of 4.3 +/- 6.4 {\mu}Gal

    A mixed methods multiple case study of implementation as usual in children’s social service organizations: study protocol

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    Background Improving quality in children’s mental health and social service settings will require implementation strategies capable of moving effective treatments and other innovations (e.g., assessment tools) into routine care. It is likely that efforts to identify, develop, and refine implementation strategies will be more successful if they are informed by relevant stakeholders and are responsive to the strengths and limitations of the contexts and implementation processes identified in usual care settings. This study will describe: the types of implementation strategies used; how organizational leaders make decisions about what to implement and how to approach the implementation process; organizational stakeholders’ perceptions of different implementation strategies; and the potential influence of organizational culture and climate on implementation strategy selection, implementation decision-making, and stakeholders’ perceptions of implementation strategies. Methods/design This study is a mixed methods multiple case study of seven children’s social service organizations in one Midwestern city in the United States that compose the control group of a larger randomized controlled trial. Qualitative data will include semi-structured interviews with organizational leaders (e.g., CEOs/directors, clinical directors, program managers) and a review of documents (e.g., implementation and quality improvement plans, program manuals, etc.) that will shed light on implementation decision-making and specific implementation strategies that are used to implement new programs and practices. Additionally, focus groups with clinicians will explore their perceptions of a range of implementation strategies. This qualitative work will inform the development of a Web-based survey that will assess the perceived effectiveness, relative importance, acceptability, feasibility, and appropriateness of implementation strategies from the perspective of both clinicians and organizational leaders. Finally, the Organizational Social Context measure will be used to assess organizational culture and climate. Qualitative, quantitative, and mixed methods data will be analyzed and interpreted at the case level as well as across cases in order to highlight meaningful similarities, differences, and site-specific experiences. Discussion This study is designed to inform efforts to develop more effective implementation strategies by fully describing the implementation experiences of a sample of community-based organizations that provide mental health services to youth in one Midwestern city

    Sediment dispersal in the northwestern Adriatic Sea

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    Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 113 (2008): C11S03, doi:10.1029/2006JC003868.Sediment dispersal in the Adriatic Sea was evaluated using coupled three-dimensional circulation and sediment transport models, representing conditions from autumn 2002 through spring 2003. The calculations accounted for fluvial sources, resuspension by waves and currents, and suspended transport. Sediment fluxes peaked during southwestward Bora wind conditions that produced energetic waves and strengthened the Western Adriatic Coastal Current. Transport along the western Adriatic continental shelf was nearly always to the south, except during brief periods when northward Sirocco winds reduced the coastal current. Much of the modeled fluvial sediment deposition was near river mouths, such as the Po subaqueous delta. Nearly all Po sediment remained in the northern Adriatic. Material from rivers that drain the Apennine Mountains traveled farther before deposition than Po sediment, because it was modeled with a lower settling velocity. Fluvial sediment delivered to areas with high average bed shear stress was more highly dispersed than material delivered to more quiescent areas. Modeled depositional patterns were similar to observed patterns that have developed over longer timescales. Specifically, modeled Po sediment accumulation was thickest near the river mouth with a very thin deposit extending to the northeast, consistent with patterns of modern sediment texture in the northern Adriatic. Sediment resuspended from the bed and delivered by Apennine Rivers was preferentially deposited on the northern side of the Gargano Peninsula, in the location of thick Holocene accumulation. Deposition here was highest during Bora winds when convergences in current velocities and off-shelf flux enhanced delivery of material to the midshelf.The authors are grateful for funding and support from the Office of Naval Research’s Coastal Geosciences and Marine Modeling programs, the U.S. Geological Survey, and NATO’s SACLANT-CEN
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