9,477 research outputs found

    Binaries with total eclipses in the LMC: potential targets for spectroscopy

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    35 Eclipsing binaries presenting unambiguous total eclipses were selected from a subsample of the list of Wyrzykowski et al. (2003). The photometric elements are given for the I curve in DiA photometry, as well as approximate Teff and masses of the components. The interest of these systems is stressed in view of future spectroscopic observations.Comment: 4 pages, 1 figure; poster presented at the conference "Close binaries in the 21st Century: new opportunities and challenges", Syros, 27-30 June 200

    Access to bank finance for Scottish SMEs.

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    There is evidence that some SMEs may still face difficulties in accessing bank finance from lenders (CEEDR, 2007). This paper reports an in-depth study into demand and supply side issues relating to access to bank finance by Scottish SMEs and whether there is still market failure associated with good, bankable business cases from SMEs that do not receive finance. We argue that our study utilises innovative methodology and is relatively rare as a robust study in this area. We combine demand side in depth survey analysis of SMEs with supply side analysis by bank managers of real business propositions through verbal protocol analysis. This paper discusses the ability of SMEs to access debt finance from the commercial banks in Scotland, it reports findings from a survey of 51 SMEs that had reported having difficulty raising finance and from interviews with bank managers utilising verbal protocol analysis with validated real SME business proposals to give insights into the decision-making of bank managers in the processing of proposals from SMEs. Theoretically, there are categories of SMEs that may face greater difficulties or contain circumstances in which it is more difficult for bank managers to apply standard decision-making models and these categories are explored to provide a theoretical framework for the investigation. The theoretical framework provides themes for discussion of the findings. These include for example; younger SMEs and owners, rural-based SMEs and manufacturing SMEs. Bank officers were found to follow standard financial models, although considerable discretion could be exercised by senior bank managers often leading to a heavy reliance on personal relationships. Smaller and newer SMEs where discretion was more limited were more likely to face difficulties. The study revealed a number of categories of SMEs that face difficulties, including strong growth SMEs in rural environments, new and young SMES,young entrepreneurs seeking start-up finance and manufacturing SMEs seeking to diversify and finance new product development. Focusing on these categories of SMEs,we analyse survey evidence, in depth case studies and verbal protocol analysis with bank managers to discuss research questions on whether informational effects can lead to market failure in the provision of debt finance, the circumstances in which sound propositions are turned down and whether such circumstances can be prevented. This forms the basis for development of conclusions on the continued existence of a debt gap for certain categories of SMEs and some policy implications

    Geographic analysis of multiple sensor data from the NASA/USGS earth resources program

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    Qualitative and quantitative analyses were made of multi-sensor data acquired during aircraft missions. While the principal analysis effort was concentrated on imagery taken over test sites in Southern California, data were also studied from records acquired on missions over test sites at Phoenix, Chicago, Asheville, and New Orleans. The objectives of the analyses were: (1) to determine the capabilities of ten remote sensors in identifying the elements of information necessary in conducting geographic investigations in land use analysis, urban problems, surface energy budget, and soil moisture; (2) to determine the feasibility of using these sensors for these purposes at orbital altitudes; and (3) to collate and analyze ground and air data previously collected and assemble it in a format useful in the accomplishment of cost effectiveness studies

    Empirical constraints on vacuum decay in the stringy landscape

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    It is generally considered as self evident that the lifetime of our vacuum in the landscape of string theory cannot be much shorter than the current age of the universe. Here I show why this lower limit is invalid. A certain type of ``parallel universes'' is a necessary consequence of the string-landscape dynamics and might well allow us to ``survive'' vacuum decay. As a consequence our stringy vacuum's lifetime is empirically unconstrained and could be very short. Based on this counter-intuitive insight I propose a novel type of laboratory experiment that searches for an apparent violation of the quantum-mechanical Born rule by gravitational effects on vacuum decay. If the lifetime of our vacuum should turn out to be shorter than 6 x 10^{-13} seconds such an experiment is sufficiently sensitive to determine its value with state-of-the-art equipment.Comment: 13 pages, 2 figures, proposes a laboratory experimen

    An Experimental Approach to a Rapid Propulsion and Aeronautics Concepts Testbed

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    Modern aircraft design tools have limitations for predicting complex propulsion-airframe interactions. The demand for new tools and methods addressing these limitations is high based on the many recent Distributed Electric Propulsion (DEP) Vertical Take-Off and Landing (VTOL) concepts being developed for Urban Air Mobility (UAM) markets. We propose that low cost electronics and additive manufacturing can support the conceptual design of advanced autonomy-enabled concepts, by facilitating rapid prototyping for experimentally driven design cycles. This approach has the potential to reduce complex aircraft concept development costs, minimize unique risks associated with the conceptual design, and shorten development schedule by enabling the determination of many "unknown unknowns" earlier in the design process and providing verification of the results from aircraft design tools. A modular testbed was designed and built to evaluate this rapid design-build-test approach and to support aeronautics and autonomy research targeting UAM applications utilizing a complex, transitioning-VTOL aircraft configuration. The testbed is a modular wind tunnel and flight model. The testbed airframe is approximately 80% printed, with labor required for assembly. This paper describes the design process, fabrication process, ground testing, and initial wind tunnel structural and thermal loading of a proof-of-concept aircraft, the Langley Aerodrome 8 (LA-8)

    User study on 3D multitouch interaction (3DMi) and gaze on surface computing

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    On a multitouch table, user’s interactions with 3D virtual representations of real objects should be influenced by task and their perceived physical characteristics. This article explores the development and user study of an interactive 3D application that allows users to explore virtual heritage objects on a surface device. To-date, most multitouch has focused on 2D or 2.5D systems. A user-study is reported where we analyse their multimodal behaviour – specifically how they interact on a surface device with objects that have similar properties to physical versions and the users’ associated gaze patterns with touch. The study reveals that gaze characteristics are different according to their interaction intention in terms of position and duration of visual attention. We discovered that virtual objects afford the perception of haptic attributes ascribed to their equivalent physical objects, and that differences in the summary statistics of gaze showed consistent characteristics between people and differences between natural and task based activities. An awareness of user behaviours using natural gestures can inform the design of interactive 3D applications which complements the user’s model of past experience with physical objects and with GUI interaction

    A comparative study of multiple imputation and subset correspondence analysis in dealing with missing data

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    Methods: Multiple imputation and subset correspondence analysis are applied to a set of child asthma data that is mainly categorical and suffers from non-response. Differences in the methods and in the outcomes they produce are studied. In addition, the inclusion of interactions in a subset correspondence analysis is illustrated. Results: Despite the vast differences in the two approaches, they yielded similar results in the identification of genetic, environmental and socio-economic factors that affect childhood asthma. A number of exposure related variables were found to be associated with the greater severity of asthma. It was also found that a finer distinction between the asthma severity levels and their associations with factors was possible with a subset correspondence analysis, compared to the multiple imputation approach. Conclusions: Both multiple imputation and subset correspondence analysis were able to identify several factors associated with childhood asthma while at the same time successfully managing the missing data. This offers the researcher a choice to select the method that best suits his/her study

    An illustrative analysis of technological alternatives for satellite communications

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    The demand for satellite communications services in the domestic market is discussed. Two approaches to increasing system capacity are the expansion of service into frequencies presently allocated but not used for satellite communications, and the development of technologies that provide a greater level of service within the currently used frequency bands. The development of economic models and analytic techniques for evaluating capacity expansion alternatives such as these are presented. The satellite orbit spectrum problem, and also outlines of some suitable analytic approaches are examined. Illustrative analysis of domestic communications satellite technology options for providing increased levels of service are also examined. The analysis illustrates the use of probabilities and decision trees in analyzing alternatives, and provides insight into the important aspects of the orbit spectrum problem that would warrant inclusion in a larger scale analysis
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