4,372 research outputs found

    Programmed schedule holds for improving launch vehicle holds

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    Baseline definition and system optimization are used for the analysis of programmed holds developed through prelaunch system analysis. Identification of design specifications for ground support equipment and maintenance concepts, and design specifications are used to describe the functional utilization of the overall flow process

    Finite-Time Singularity Signature of Hyperinflation

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    We present a novel analysis extending the recent work of Mizuno et al. [2002] on the hyperinflations of Germany (1920/1/1-1923/11/1), Hungary (1945/4/30-1946/7/15), Brazil (1969-1994), Israel (1969-1985), Nicaragua (1969-1991), Peru (1969-1990) and Bolivia (1969-1985). On the basis of a generalization of Cagan's model of inflation based on the mechanism of ``inflationary expectation'' or positive feedbacks between realized growth rate and people's expected growth rate, we find that hyperinflations can be characterized by a power law singularity culminating at a critical time tct_c. Mizuno et al.'s double-exponential function can be seen as a discrete time-step approximation of our more general nonlinear ODE formulation of the price dynamics which exhibits a finite-time singular behavior. This extension of Cagan's model, which makes natural the appearance of a critical time tct_c, has the advantage of providing a well-defined end of the clearly unsustainable hyperinflation regime. We find an excellent and reliable agreement between theory and data for Germany, Hungary, Peru and Bolivia. For Brazil, Israel and Nicaragua, the super-exponential growth seems to be already contaminated significantly by the existence of a cross-over to a stationary regime.Comment: Latex 21 pages including 2 tables and 7 eps figure

    International Public Health Research Involving Interpreters: a Case Study from Bangladesh

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    Background: Cross-cultural and international research are important components of public health research, but the challenges of language barriers and working with interpreters are often overlooked, particularly in the case of qualitative research. Methods: A case-study approach was used to explore experiences of working with an interpreter in Bangladesh as part of a research project investigating women's experiences of emergency obstetric care. The case study: Data from the researcher's field notes provided evidence of experiences in working with an interpreter and show how the model of interviewing was adapted over time to give a more active role to the interpreter. The advantages of a more active role were increased rapport and "flow" in interviews. The disadvantages included reduced control from the researcher's perspective. Some tensions between the researcher and interpreter remained hard to overcome, irrespective of the model used. Independent transcription and translation of the interviews also raised questions around accuracy in translation. Conclusion: The issues examined in this case study have broader implications for public health research. Further work is needed in three areas: 1) developing effective relationships with interpreters; 2) the impact of the interpreter on the research process; and 3) the accuracy of the translation and level of analysis needed in any specific public health research. Finally, this paper highlights the importance to authors of reflecting on the potential impact of translation and interpretation on the research process when disseminating their research

    The processing of number scales beyond whole numbers in development: Dissociations in arithmetic in Turner’s syndrome

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    The arithmetical skills in two children with Turner’s syndrome (TS), each the focus of a case study, were analysed in whole numbers and other number scales that have not been systematically explored previously, fractions, decimals, percentages, and negative numbers. The intention was to identify the fractionation of arithmetical skills. The two girls with TS showed dissociations of arithmetical skill in the calculation system of whole numbers that support its modular organization. Fractionation of skills was observed in some components of the other number scales, suggesting an analogous organization within these scales. The operational specificity of impairment within number scales but not others argued against a unitary arithmetical system but rather for autonomous operational scales within distinct number scales. A general model of arithmetic is proposed

    WASP-189b: an ultra-hot Jupiter transiting the bright A star HR 5599 in a polar orbit

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    We report the discovery of WASP-189b: an ultra-hot Jupiter in a 2.72-d transiting orbit around the V=6.6V = 6.6 A star WASP-189 (HR 5599). We detected periodic dimmings in the star's lightcurve, first with the WASP-South survey facility then with the TRAPPIST-South telescope. We confirmed that a planet is the cause of those dimmings via line-profile tomography and radial-velocity measurements using the HARPS and CORALIE spectrographs. Those reveal WASP-189b to be an ultra-hot Jupiter (MPM_{\rm P} = 2.13 ±\pm 0.28 MJupM_{\rm Jup}; RPR_{\rm P} = 1.374 ±\pm 0.082 RJupR_{\rm Jup}) in a polar orbit (λ=89.3±1.4\lambda = 89.3 \pm 1.4^\circ; Ψ=90.0±5.8\Psi = 90.0 \pm 5.8^\circ) around a rapidly rotating A6IV-V star (TeffT_{\rm eff} = 8000 ±\pm 100 K; vsiniv_* \sin i_* \approx 100 km\, s1^{-1}). We calculate a predicted equilibrium temperature of TeqlT_{\rm eql} = 2641 ±\pm 34 K, assuming zero albedo and efficient redistribution, which is the third hottest for the known exoplanets. WASP-189 is the brightest known host of a transiting hot Jupiter and the third-brightest known host of any transiting exoplanet. We note that of the eight hot-Jupiter systems with TeffT_{\rm eff} >> 7000 K, seven have strongly misaligned orbits, and two of the three systems with TeffT_{\rm eff} \geq 8000 K have polar orbits (the third is aligned).Comment: Submitted to MNRAS. 10 pages, 9 figures, 3 table

    A low-density hot Jupiter in a near-aligned, 4.5-day orbit around a VV = 10.8, F5V star

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    We report the independent discovery and characterisation of a hot Jupiter in a 4.5-d, transiting orbit around the star TYC 7282-1298-1 (VV = 10.8, F5V). The planet has been pursued by the NGTS team as NGTS-2b and by ourselves as WASP-179b. We characterised the system using a combination of photometry from WASP-South and TRAPPIST-South, and spectra from CORALIE (around the orbit) and HARPS (through the transit). We find the planet's orbit to be nearly aligned with its star's spin. From a detection of the Rossiter-McLaughlin effect, we measure a projected stellar obliquity of λ=19±6\lambda = -19 \pm 6^\circ. From line-profile tomography of the same spectra, we measure λ=11±5\lambda = -11 \pm 5^\circ. We find the planet to have a low density (MPM_{\rm P} = 0.67 ±\pm 0.09 MJupM_{\rm Jup}, RPR_{\rm P} = 1.54 ±\pm 0.06 RJupR_{\rm Jup}), which, along with its moderately bright host star, makes it a good target for transmission spectroscopy. We find a lower stellar mass (MM_* = 1.30±0.071.30 \pm 0.07 MM_\odot) than reported by the NGTS team (MM_* = 1.64±0.211.64 \pm 0.21 MM_\odot), though the difference is only 1.51.5 σ\sigma.Comment: Submitted to AJ. 9 pages, 6 figures, 5 table

    Ground State Energy of the Low Density Bose Gas

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    Now that the properties of low temperature Bose gases at low density, ρ\rho, can be examined experimentally it is appropriate to revisit some of the formulas deduced by many authors 4-5 decades ago. One of these is that the leading term in the energy/particle is 2π2ρa/m2\pi \hbar^2 \rho a/m, where aa is the scattering length. Owing to the delicate and peculiar nature of bosonic correlations, four decades of research have failed to establish this plausible formula rigorously. The only known lower bound for the energy was found by Dyson in 1957, but it was 14 times too small. The correct bound is proved here.Comment: 4 pages, Revtex, reference 12 change
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