635 research outputs found

    Variable geometry inlet design for scram jet engine

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    The present invention relates to an improved variable geometry inlet for a scram jet engine having at least one combustor module. The variable geometry inlet comprises each combustor module having two sidewalls. Each of the sidewalls has a central portion with a thickness and a tapered profile forward of the central portion. The tapered profile terminates in a sharp leading edge. The variable geometry inlet further comprises each module having a lower wall and a movable cowl flap positioned forward of the lower wall. The movable cowl flap has a leading edge and the leading edges of the sidewalls intersect the leading edge of the cowl flap

    Intermediate and narrow band photometry of Epsilon Aurigae

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    Intermediate band blue (4530A), far red (7790A) and H-alpha intermediate and narrow band photoelectric observations of the peculiar, 27 year eclipsing binary, Epsilon Aurigae were made from December 1981 through the present (December 1984). BD +42 1170 served as the primary comparison star because of its angular proximity to the variable star. The analysis of this data along with other available photometry was undertaken to study the characteristics of the low amplitude, semi-regular light variations that appear inside and outside of eclipse. It appears that these short term light variations arise from nonradial pulsations of the luminous f supergiant in the system. Furthermore, the semi-regular light variations found for Epsilon Aurigae are similar to those found for other luminous A-F supergiants. Also, the preliminary results from the analyses of the light variations produced by the eclipse of the F-supergiant by the mysterious cooler component is discussed

    The Distance to the Large Magellanic Cloud from the Eclipsing Binary HV2274

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    The distance to the Large Magellanic Cloud (LMC) is crucial for the calibration of the Cosmic Distance Scale. We derive a distance to the LMC based on an analysis of ground-based photometry and HST-based spectroscopy and spectrophotometry of the LMC eclipsing binary system HV2274. Analysis of the optical light curve and HST/GHRS radial velocity curve provides the masses and radii of the binary components. Analysis of the HST/FOS UV/optical spectrophotometry provides the temperatures of the component stars and the interstellar extinction of the system. When combined, these data yield a distance to the binary system. After correcting for the location of HV2274 with respect to the center of the LMC, we find d(LMC) = 45.7 +/- 1.6 kpc or DM(LMC) = 18.30 +/- 0.07 mag. This result, which is immune to the metallicity-induced zero point uncertainties that have plagued other techniques, lends strong support to the ``short'' LMC distance scale as derived from a number of independent methods.Comment: 6 pages, including 2 pages of figures. Newly available optical (B and V) photometry has revealed -- and allowed the elimination of -- a systematic error in the previously reported determination of E(B-V) for HV2274. The new result is E(B-V) = 0.12 mag (as compared to the value of 0.083 reported in the original submission) and produces a DECREASE in the distance modulus of HV2274 by 0.12 mag. ApJ Letters, in pres

    Intentional Foreign Body Ingestion: A Complex Case of Pica

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    Intentional ingestion of foreign objects, a form of self-injurious behavior, is rarely discussed in the medical literature but often requires extensive evaluation, management, and resources. It can be especially problematic for gastroenterologists, who are often consulted for removal of the foreign body. Pica is the psychiatric diagnosis for intentional ingestion of nonnutritive objects and is most commonly seen in prison inmates and those diagnosed with intellectual disability or psychiatric illness. This case report presents a challenging case of pica, highlighting the complexity involved in diagnosis and the need for early psychiatric intervention. It also aims to provide a general review of the literature and practical recommendations to assist with managing this form of self-injurious behavior in the inpatient setting. Collaborative efforts among specialties in addition to primary prevention are vital to successful management of these patients

    Magnetic field and wind of Kappa Ceti: towards the planetary habitability of the young Sun when life arose on Earth

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    We report magnetic field measurements for Kappa1~Cet, a proxy of the young Sun when life arose on Earth. We carry out an analysis of the magnetic properties determined from spectropolarimetric observations and reconstruct its large-scale surface magnetic field to derive the magnetic environment, stellar winds and particle flux permeating the interplanetary medium around Kappa1~Cet. Our results show a closer magnetosphere and mass-loss rate of Mdot = 9.7 x 10^{-13} Msol/yr, i.e., a factor 50 times larger than the current solar wind mass-loss rate, resulting in a larger interaction via space weather disturbances between the stellar wind and a hypothetical young-Earth analogue, potentially affecting the planet's habitability. Interaction of the wind from the young Sun with the planetary ancient magnetic field may have affected the young Earth and its life conditionsComment: 6 pages, 5 figures, Published at the Astrophysical Journal Letters (ApJL): Manuscript #LET3358

    Eclipsing Binaries as Astrophysical Laboratories: Internal Structure, Convective Core Overshooting and Evolution of the B-star Components of V380 Cygni

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    New photometric solutions have been carried out on the important eccentric eclipsing system V380 Cygni (B1.5II-III + B2V) from UBV differential photoelectric photometry obtained by us. The photometric elements obtained from the analysis of the light curves have been combined with the spectroscopic solution recently published by Popper & Guinan and have led to the physical properties of the system components. The effective temperature of the stars has been determined by fitting IUE UV spectrophotometry to Kurucz model atmospheres and compared with other determinations from broad-band and intermediate-band standard photometry. The values of mass, absolute radius, and effective temperature, for the primary and secondary stars are: 11.1+/-0.5 Mo, 14.7+/-0.2 Ro, 21350+/-400 K, and 6.95+/-0.25 Mo, 3.74+/-0.07 Ro, 20500+/-500 K, respectively. In addition, a re-determination of the system's apsidal motion rate has been done from the analysis of 12 eclipse timings obtained from 1923 to 1995. Using stellar structure and evolutionary models with modern input physics, tests on the extent of convection in the core of the more massive star of the system have been carried out. Both the analysis of the log g-log Teff diagram and the apsidal motion study indicate a star with a larger convective core, and thus more centrally condensed, than currently assumed. This has been quantified in form of an overshooting parameter with a value of 0.6+/-0.1. Finally, the tidal evolution of the system (synchronization and circularization times) has also been studied.Comment: 23 pages, 5 figures, version accepted for publication in Ap

    Helicobacter pylori-induced inhibition of vascular endothelial cell functions: a role for VacA-dependent nitric oxide reduction

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    Epidemiological and clinical studies provide compelling support for a causal relationship between Helicobacter pylori infection and endothelial dysfunction, leading to vascular diseases. However, clear biochemical evidence for this association is limited. In the present study, we have conducted a comprehensive investigation of endothelial injury in bovine aortic endothelial cells (BAECs) induced by H. pylori-conditioned medium (HPCM) prepared from H. pylori 60190 [vacuolating cytotoxin A (Vac(+))]. BAECs were treated with either unconditioned media, HPCM (0-25% vol/vol), or Escherichia coli-conditioned media for 24 h, and cell functions were monitored. Vac(+) HPCM significantly decreased BAEC proliferation, tube formation, and migration (by up to 44%, 65%, and 28%, respectively). Posttreatment, we also observed sporadic zonnula occludens-1 immunolocalization along the cell-cell border, and increased BAEC permeability to FD40 Dextran, indicating barrier reduction. These effects were blocked by 5-nitro-2-(3-phenylpropylamino)benzoic acid (VacA inhibitor) and were not observed with conditioned media prepared from either VacA-deleted H. pylori or E. coli. The cellular mechanism mediating these events was also considered. Vac(+) HPCM (but not Vac(-)) reduced nitric oxide (NO) by \u3e50%, whereas S-nitroso-N-acetylpenicillamine, an NO donor, recovered all Vac(+) HPCM-dependent effects on cell functions. We further demonstrated that laminar shear stress, an endothelial NO synthase/NO stimulus in vivo, could also recover the Vac(+) HPCM-induced decreases in BAEC functions. This study shows, for the first time, a significant proatherogenic effect of H. pylori-secreted factors on a range of vascular endothelial dysfunction markers. Specifically, the VacA-dependent reduction in endothelial NO is indicated in these events. The atheroprotective impact of laminar shear stress in this context is also evident
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