10,416 research outputs found

    The Energy Transfer Process in Planetary Flybys

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    We illustrate the energy transfer during planetary flybys as a function of time using a number of flight mission examples. The energy transfer process is rather more complicated than a monotonic increase (or decrease) of energy with time. It exhibits temporary maxima and minima with time which then partially moderate before the asymptotic condition is obtained. The energy transfer to angular momentum is exhibited by an approximate Jacobi constant for the system. We demonstrate this with flybys that have shown unexplained behaviors: i) the possible onset of the "Pioneer anomaly" with the gravity assist of Pioneer 11 by Saturn to hyperbolic orbit (as well as the Pioneer 10 hyperbolic gravity assist by Jupiter) and ii) the Earth flyby anomalies of small increases in energy {\it in the geocentric system} (Galileo-I, NEAR, and Rosetta, in additioon discussing the Cassini and Messenger flybys). Perhaps some small, as yet unrecognized effect in the energy-transfer process can shed light on these anomalies.Comment: 29 pages, 43 images combined into 13 figures. Additions to answer comments of refere

    Investigating The Necessary Components of a Sarcastic Context

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    This research is designed to investigate the contextual components utilized to convey sarcastic verbal irony, testing whether theoretical components deemed as necessary for creating a sense of irony are, in fact, necessary. A novel task was employed: Given a set of statements that out-of-context were not rated as sarcastic, participants were instructed to either generate discourse context that would make the statements sarcastic or meaningful (without further specification). In a series of studies these generated contexts were shown to differ from one another along the dimensions presumed as necessary (failed expectation, pragmatic insincerity, negative tension and presence of a victim) and along stylistic components (as indexed by the LIWC). However, none of these components were found to be necessary. Indeed in each case the items rated as highest in sarcasm were often at the lowest levels on the putative “necessary” characteristic. The ratings were then used to develop an online reading task to investigate the effect of negative tension on the processing of sarcastic and literal statements. Three groups of items were taken from the previous studies to form high negative tension; low negative tension; and literal statements. Reading times for seven key areas were compared across the three groups and it was found that in two of the critical areas, the low negative items were processed significantly more slowly than the other two sets of items. The literal and high negative items however did not differ significantly in their processing times. These findings support the predictions of direct access models and contradict the predictions of the standard pragmatic model of language processing. The findings from the studies are seen as consistent with constraint satisfaction models of sarcasm processing in which various linguistic and extralinguistic information provide probabilistic (but not necessary) support for or against a sarcastic interpretation

    Integrated support structure

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    This Major Qualifying Project is part of the Advanced Space Design Program at WPI. The goal is to design a support structure for a NASA GetAway Special experimental canister. The payload integration, weight, volume, and structural integrity of the canister as specified by NASA guidelines were studied. The end result is a complete set of design drawings with interface drawings and data to specify the design and leave a base on which the next group can concentrate

    Higgs Boson Production in Weak Boson Fusion at Next-to-Leading Order

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    The weak boson fusion process for neutral Higgs boson production is investigated with particular attention to the accuracy with which the Higgs boson coupling to weak bosons can be determined at CERN Large Hadron Collider (LHC) energies in final states that contain a Higgs boson plus at least two jets. Using fully differential perturbative matrix elements for the weak boson fusion signal process and for the QCD background processes, we generate events in which a Higgs boson is produced along with two jets that carry large transverse momentum. The effectiveness of different prescriptions to enhance the signal to background ratio is studied, and the expected signal purities are calculated in each case. We find that a simple cut on the rapidity of one final-state jet works well. We determine that an accuracy of delta_g/g ~ 10% on the effective coupling g may be possible after ~ 200 fb^-1 of integrated luminosity is accumulated at the LHC.Comment: 34 pages. Some restructuring of the text, a few sentences and one figure added. Conclusions not altered. To be published in Physical Review

    Imine Azaenolates: Synthesis, Reactivity, and Outlook

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    Azaenolates are, quite simply, the aza variant of enolates. Compared to their oxygen counterparts, additional control of the reactivity of azaenolates can be achieved by altering the substituent on the nitrogen atom as well as the metal counterion. Since the seminal examples reported in the early 1960s, azaenolates of various metals have been shown to react with a diverse set of electrophilic partners, including challenging electrophiles such as alkyl fluorides, epoxides, and oxetanes. This review describes in detail the current state of the art of the chemistry of azaenolates derived from imines, with a particular focus on the comparison of the reactivity exhibited with different metal counterions

    Who Financed the Expansion of the Equity Market? Shareholder Clienteles in Victorian Britain

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    Who financed the great expansion of the Victorian equity market, and what attracted them to invest? Using data on 453 firm-years and over 172,000 shareholders, we find that the largest providers of capital were rentiers, men with no formal occupation who relied on investment income. We also see a substantial growth in women investors as time progressed. In terms of clientele effects, we find that rentiers invested in large firms, whilst businessmen were the venture capitalists of young, regional enterprises. Women and the middle classes preferred safe investments, whilst financiers and institutional investors were speculators in foreign companies. Our results may help to explain the growth of new types of assets catering for particular clienteles, and the development of managerial policies on dividends and share issues

    Understanding the Role of Theory on Instrument Development: An Examination of Strengths and Weaknesses of Discriminant Validity Analysis Techniques

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    Numerous researchers have called attention to many important issues in instrument development throughout the relatively short history of the information systems (IS) academic research discipline (e.g., Petter, Straub, & Rai 2007; Straub, Boudreau, & Gefen 2004; Straub 1989). With the accumulation of knowledge related to the process of instrument development, it has now become necessary to take a closer look at specific aspects of this process. This paper focuses on construct validity, specifically discriminant validity, and examines some popular methods of supporting this type of validity when using cross-sectional data. We examine strengths and weaknesses of these analysis techniques with a focus on the role of theory and informed interpretation. We highlight the applicability of these techniques by analyzing a sample dataset where we theorize two constructs to be highly correlated. With this paper, we provide both researchers and reviewers a greater understanding of the highlighted discriminant validity analysis techniques

    A phase 1 trial of nebulised heparin in acute lung injury

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    INTRODUCTION: Animal studies of acute lung injury (ALI) suggest nebulised heparin may limit damage from fibrin deposition in the alveolar space and microcirculation. No human studies have been undertaken to date. We assessed the feasibility, safety and potential anticoagulant effects of administration of nebulised heparin to patients with ALI. METHODS: An open label phase 1 trial of four escalating doses of nebulised heparin was performed. A total of 16 ventilated patients with ALI were studied. The first group was administered a total of 50,000 U/day, the second group 100,000 U/day, the third group 200,000 U/day and the fourth group 400,000 U/day. Assessments of lung function included the PaO2/FiO2 ratio, lung compliance and the alveolar dead space fraction. Monitoring of anticoagulation included the activated partial thromboplastin time (APTT) and the thrombin clotting time. Bronchoalveolar lavage fluid was collected and the prothrombin fragment and tissue plasminogen activator levels were assessed. Analysis of variance was used to compare the effects of dose. RESULTS: No serious adverse events occurred for any dose. The changes over time for the PaO2/FiO2 ratio, lung compliance and the alveolar dead space fraction levels were similar for all doses. A trend to increased APTT and thrombin clotting time levels was present with higher doses (P = 0.09 and P = 0.1, respectively). For the highest dose, the APTT reached 64 seconds; following cessation of nebulised heparin, the APTT fell to 39 seconds (P = 0.06). In bronchoalveolar lavage samples a trend to reduced prothrombin fragment levels was present with higher doses (P = 0.1), while tissue plasminogen activator levels were similar for all doses. CONCLUSION: Administration of nebulised heparin to mechanically ventilated patients with ALI is feasible. Nebulised heparin was not associated with any serious adverse events, and at higher doses it increased APTT levels. Larger trials are required to further investigate the safety and efficacy of nebulised heparin. In these trials due consideration must be given to systemic anticoagulant effects. TRIAL REGISTRATION: Australian Clinical trials registry ACTRN12606000388516
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