1,050 research outputs found

    JT9D engine diagnostics. Task 2: Feasibility study of measuring in-service flight loads

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    The feasibility of measuring JT9D propulsion system flight inertia loads on a 747 airplane is studied. Flight loads background is discussed including the current status of 747/JT9D loads knowledge. An instrumentation and test plan is formulated for an airline-owned in-service airplane and the Boeing-owned RA001 test airplane. Technical and cost comparisons are made between these two options. An overall technical feasibility evaluation is made and a cost summary presented. Conclusions and recommendations are presented in regard to using existing inertia loads data versus conducting a flight test to measure inertia loads

    Coherence Time in High Energy Proton-Nucleus Collisions

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    Precisely measured Drell-Yan cross sections for 800 GeV protons incident on a variety of nuclear targets exhibit a deviation from linear scaling in the atomic number A. We show that this deviation can be accounted for by energy degradation of the proton as it passes through the nucleus if account is taken of the time delay of particle production due to quantum coherence. We infer an average proper coherence time of 0.4 +- 0.1 fm/c, corresponding to a coherence path length of 8 +- 2 fm in the rest frame of the nucleus.Comment: 11 pages in LaTeX. Includes 6 eps figures. Uses epsf.st

    Discovery of Halpha satellite emission in a low state of the SW Sextantis star BB Doradus

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    BB Dor was observed during its low state state in 2009. Signatures of both binary components are revealed in the average optical spectrum; no signature of accretion is observed. Narrow emission lines of Halpha, HeI and Na-D, as well as TiO absorption troughs trace the motion of the irradiated secondary star. We detect two additional components in the Halpha emission line that share many characteristics of similar "satellite" lines observed in the low state of magnetic cataclysmic variables of AM Her type. It is the first time such emission components are detected for an SW Sex star.Comment: 7 pages, 8 figures, accepted by MNRA

    GALEX and Optical Light Curves of WX LMi, SDSSJ103100.5+202832.2 and SDSSJ121209.31+013627.7

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    {\it GALEX} near ultraviolet (NUV) and far-ultraviolet (FUV) light curves of three extremely low accretion rate polars show distinct modulations in their UV light curves. While these three systems have a range of magnetic fields from 13 to 70 MG, and of late type secondaries (including a likely brown dwarf in SDSSJ121209.31+013627.7), the accretion rates are similar, and the UV observations imply some mechanism is operating to create enhanced emission zones on the white dwarf. The UV variations match in phase to the two magnetic poles viewed in the optical in WX LMi and to the single poles evident in the optical in SDSSJ1212109.31+013627.7 and SDSSJ103100.55+202832.2. Simple spot models of the UV light curves show that if hot spots are responsible for the UV variations, the temperatures are on the order of 10,000-14,000K. For the single pole systems, the size of the FUV spot must be smaller than the NUV and in all cases, the geometry is likely more complicated than a simple circular spot.Comment: 29 pages, 4 tables, 10 figures, Astrophysical Journal, accepte

    The fight for accretion: discovery of intermittent mass transfer in BB Doradus in the low state

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    Our long-term photometric monitoring of southern nova-like cataclysmic variables with the 1.3-m SMARTS telescope found BB Doradus fading from V ~ 14.3 towards a deep low state at V ~ 19.3 in April 2008. Here we present time-resolved optical spectroscopy of BB Dor in this faint state in 2009. The optical spectrum in quiescence is a composite of a hot white dwarf with Teff = 30000 +- 5000 K and a M3-4 secondary star with narrow emission lines (mainly of the Balmer series and HeI) superposed. We associate these narrow profiles with an origin on the donor star. Analysis of the radial velocity curve of the H-alpha emission from the donor star allowed the measurement of an orbital period of 0.154095 +- 0.000003 d (3.69828 +- 0.00007 h), different from all previous estimates. We detected episodic accretion events which veiled the spectra of both stars and radically changed the line profiles within a timescale of tens of minutes. This shows that accretion is not completely quenched in the low state. During these accretion episodes the line wings are stronger and their radial velocity curve is delayed by ~ 0.2 cycle, similar to that observed in SW Sex and AM Her stars in the high state, with respect to the motion of the white dwarf. Two scenarios are proposed to explain the extra emission: impact of the material on the outer edge of a cold, remnant accretion disc, or the combined action of a moderately magnetic white dwarf (B1 <~ 5 MG) and the magnetic activity of the donor star.Comment: 10 pages, 10 figures, accepted by MNRA

    The influence of the geomagnetic field and of the uncertainties in the primary spectrum on the development of the muon flux in the atmosphere

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    In this paper we study the sensitivity of the flux of atmospheric muons to uncertainties in the primary cosmic ray spectrum and to the treatment of the geomagnetic field in a calculation. We use the air shower simulation program AIRES to make the calculation for two different primary spectra and under several approximations to the propagation of charged particles in the geomagnetic field. The results illustrate the importance of accurate modelling of the geomagnetic field effects. We propose a high and a low fit of the proton and helium fluxes, and calculate the muon fluxes with these different inputs. Comparison with measurements of the muon flux by the CAPRICE experiment shows a slight preference for the higher primary cosmic ray flux parametrization.Comment: 24 pages, 13 figures, submitted to Phys.Rev.

    The Factory and The Beehive II. Activity and Rotation in Praesepe and the Hyades

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    Open clusters are collections of stars with a single, well-determined age, and can be used to investigate the connections between angular-momentum evolution and magnetic activity over a star's lifetime. We present the results of a comparative study of the relationship between stellar rotation and activity in two benchmark open clusters: Praesepe and the Hyades. As they have the same age and roughly solar metallicity, these clusters serve as an ideal laboratory for testing the agreement between theoretical and empirical rotation-activity relations at \approx600 Myr. We have compiled a sample of 720 spectra --- more than half of which are new observations --- for 516 high-confidence members of Praesepe; we have also obtained 139 new spectra for 130 high-confidence Hyads. We have collected rotation periods (ProtP_{rot}) for 135 Praesepe members and 87 Hyads. To compare HαH\alpha emission, an indicator of chromospheric activity, as a function of color, mass, and Rossby number RoR_o, we first calculate an expanded set of χ\chi values, with which we can obtain the HαH\alpha to bolometric luminosity ratio, LHα/LbolL_{H\alpha}/L_{bol}, even when spectra are not flux-calibrated and/or stars lack reliable distances. Our χ\chi values cover a broader range of stellar masses and colors (roughly equivalent to spectral types from K0 to M9), and exhibit better agreement between independent calculations, than existing values. We find no difference between the two clusters in their HαH\alpha equivalent width or LHα/LbolL_{H\alpha}/L_{bol} distributions, and therefore take the merged HαH\alpha and ProtP_{rot} data to be representative of 600-Myr-old stars. Our analysis shows that HαH\alpha activity in these stars is saturated for Ro0.110.03+0.02R_o\leq0.11^{+0.02}_{-0.03}. Above that value activity declines as a power-law with slope β=0.730.12+0.16\beta=-0.73^{+0.16}_{-0.12}, before dropping off rapidly at Ro0.4R_o\approx0.4...Comment: 17 pages, 15 figures, Accepted by Ap

    Understanding the role of shame and its consequences in female hypersexual behaviours: A pilot study

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    Background and aims: Hypersexuality and sexual addiction among females is a little understudied phenomenon. Shame is thought to be intrinsic to hypersexual behaviours, especially in women. Therefore, the aim of this study was to understand both hypersexual behaviours and consequences of hypersexual behaviours and their respective contributions to shame in a British sample of females (n = 102). Methods: Data were collected online via Survey Monkey. Results: Results showed the Sexual Behaviour History (SBH) and the Hypersexual Disorder Questionnaire (HDQ) had significant positive correlation with scores on the Shame Inventory. The results indicated that hypersexual behaviours (HBI and HDQ) were able to predict a small percentage of the variability in shame once sexual orientation (heterosexual vs. non-heterosexual) and religious beliefs (belief vs. no belief) were controlled for. Results also showed there was no evidence that religious affiliation and/or religious beliefs had an influence on the levels of hypersexuality and consequences of sexual behaviours as predictors of shame. Conclusions: While women in the UK are rapidly shifting to a feminist way of thinking with or without technology, hypersexual disorder may often be misdiagnosed and misunderstood because of the lack of understanding and how it is conceptualised. The implications of these findings are discussed

    CP Violation and Matter Effect in Long Baseline Neutrino Oscillation Experiments

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    We show simple methods how to separate pure CP violating effect from matter effect in long baseline neutrino oscillation experiments with three generations of neutrinos. We give compact formulae for neutrino oscillation probabilities assuming one of the three neutrino masses (presumably tau-neutrino mass) to be much larger than the other masses and the effective mass due to matter effect. Two methods are shown: One is to observe envelopes of the curves of oscillation probabilities as functions of neutrino energy; a merit of this method is that only a single detector is enough to determine the presence of CP violation. The other is to compare experiments with at least two different baseline lengths; this has a merit that it needs only narrow energy range of oscillation data.Comment: 17 pages + 9 eps figures, LaTeX, errors are correcte
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