3,060 research outputs found

    PKS 1004+13: A High-Inclination, Highly-Absorbed Radio-Loud QSO -- The First Radio-Loud BAL QSO at Low Redshift?

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    The existence of BAL outflows in only radio-quiet QSOs was thought to be an important clue to mass ejection and the radio-loud - radio-quiet dichotomy. Recently a few radio-loud BAL QSOs have been discovered at high redshift. We present evidence that PKS 1004+13 is a radio-loud BAL QSO. It would be the first known at low-redshift (z = 0.24), and one of the most radio luminous. For PKS 1004+13, there appear to be broad absorption troughs of O VI, N V, Si IV, and C IV, indicating high-ionization outflows up to about 10,000 km/s. There are also two strong, broad (~500 km/s), high-ionization, associated absorption systems that show partial covering of the continuum source. The strong UV absorption we have detected suggests that the extreme soft-X-ray weakness of PKS 1004+13 is primarily the result of absorption. The large radio-lobe dominance indicates BAL and associated gas at high inclinations to the central engine axis, perhaps in a line-of-sight that passes through an accretion disk wind.Comment: To appear in Ap.J. Letters, 1999 (June or July); 4 pages, 5 figure

    Short-wavelength out-of-band EUV emission from Sn laser-produced plasma

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    We present the results of spectroscopic measurements in the extreme ultraviolet (EUV) regime (7-17 nm) of molten tin microdroplets illuminated by a high-intensity 3-J, 60-ns Nd:YAG laser pulse. The strong 13.5 nm emission from this laser-produced plasma is of relevance for next-generation nanolithography machines. Here, we focus on the shorter wavelength features between 7 and 12 nm which have so far remained poorly investigated despite their diagnostic relevance. Using flexible atomic code calculations and local thermodynamic equilibrium arguments, we show that the line features in this region of the spectrum can be explained by transitions from high-lying configurations within the Sn8+^{8+}-Sn15+^{15+} ions. The dominant transitions for all ions but Sn8+^{8+} are found to be electric-dipole transitions towards the nn=4 ground state from the core-excited configuration in which a 4pp electron is promoted to the 5ss sub-shell. Our results resolve some long-standing spectroscopic issues and provide reliable charge state identification for Sn laser-produced plasma, which could be employed as a useful tool for diagnostic purposes.Comment: 11 pages, 4 figure

    Heritability of testosterone levels in 12-year-old twins and its relation to pubertal development

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    The aim of this study was to estimate the heritability of variation in testosterone levels in 12-year-old children, and to explore the overlap in genetic and environmental influences on circulating testosterone levels and androgen dependent pubertal development. Midday salivary testosterone samples were collected on two consecutive days in a sample of 183 unselected twin pairs. Androgen induced pubertal development was assessed using self report Tanner scales of pubic hair development (boys and girls) and genital development (boys). A significant contribution of genetic effects to the variance in testosterone levels was found. Heritability was approximately 50% in both boys and girls. The remaining proportion of the variance in testosterone levels could be explained by non-shared environmental influences. The relatively high correlation between testosterone levels of opposite sex dizygotic twins suggests that sex differences in genes influencing variation in testosterone levels have not yet developed in pre- and early puberty. Variance in pubertal development was explained by a large genetic component, moderate shared environmental influences, and a small non-shared environmental effect. Testosterone levels correlated moderately (r = .31) with pubertal development; the covariance between testosterone levels and pubertal development was entirely accounted for by genetic influences

    Evidence for Non-Hydrostatic Gas from the Cluster X-ray to Lensing Mass Ratio

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    Using a uniform analysis procedure, we measure spatially resolved weak gravitational lensing and hydrostatic X-ray masses for a sample of 18 clusters of galaxies. We find a radial trend in the X-ray to lensing mass ratio: at r2500 we obtain a ratio MX/ML=1.03+/-0.07 which decreases to MX/ML=0.78+/-0.09 at r500. This difference is significant at 3 sigma once we account for correlations between the measurements. We show that correcting the lensing mass for excess correlated structure outside the virial radius slightly reduces, but does not eliminate this trend. An X-ray mass underestimate, perhaps due to nonthermal pressure support, can explain the residual trend. The trend is not correlated with the presence or absence of a cool core. We also examine the cluster gas fraction and find no correlation with ML, an important result for techniques that aim to determine cosmological parameters using the gas fraction.Comment: 8 pages, minor modifications, accepted for publication in MNRA

    Increase of sentinel lymph node melanoma staging in The Netherlands; still room and need for further improvement

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    Aim: To investigate implementation of the seventh American Joint Committee on Cancer melanoma staging with sentinel lymph node biopsy (SLNB) and associations with socioeconomic status (SES). Patients & methods: Data from The Netherlands Cancer Registry on patient and tumor characteristics were analyzed for all stage IB-II melanoma cases diagnosed 2010-2016, along with SES data from The Netherlands Institute for Social Research. Results: The proportion of SLNB-staged patients increased from 40% to 65% (p <0.001). Multivariate analysis showed that being female, elderly, or having head-and-neck disease reduced the likelihood of SLNB staging. Conclusion: SLNB staging increased by 25% during the study period but lagged among elderly patients and those with head-and-neck melanoma. In The Netherlands, SES no longer affects SLNB staging performance

    Microdroplet-tin plasma sources of EUV radiation driven by solid-state-lasers (Topical Review)

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    Plasma produced from molten-tin microdroplets generates extreme ultraviolet light for state-of-the-art nanolithography. Currently, CO2 lasers are used to drive the plasma. In the future, solid-state mid-infrared lasers may instead be used to efficiently pump the plasma. Such laser systems have promise to be more compact, better scalable, and have higher wall-plug efficiency. In this Topical Review, we present recent findings made at the Advanced Research Center for Nanolithography (ARCNL) on using 1 and 2 μm wavelength solid-state lasers for tin target preparation and for driving hot and dense plasma. The ARCNL research ranges from advanced laser development, studies of fluid dynamic response of droplets to impact, radiation-hydrodynamics calculations of, e.g. ion 'debris', (EUV) spectroscopic studies of tin laser-produced-plasma as well as high-conversion efficiency operation of 2 μm wavelength driven plasma

    Optical spectroscopy of complex open 4dd-shell ions Sn7+^{7+}-Sn10+^{10+}

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    We analyze the complex level structure of ions with many-valence-electron open [Kr] 4dmd^\textrm{m} sub-shells (m\textrm{m}=7-4) with ab initio calculations based on configuration-interaction many-body perturbation theory (CI+MBPT). Charge-state-resolved optical and extreme ultraviolet (EUV) spectra of Sn7+^{7+}-Sn10+^{10+} ions were obtained using an electron beam ion trap. Semi-empirical spectral fits carried out with the orthogonal parameters technique and Cowan code calculations lead to 90 identifications of magnetic-dipole transitions and the determination of 79 energy ground-configuration levels, questioning some earlier EUV-line assignments. Our results, the most complete data set available to date for these ground configurations, confirm the ab initio predictive power of CI+MBPT calculations for the these complex electronic systems.Comment: 18 pages, 5 figure

    Optical pumping of trapped neutral molecules by blackbody radiation

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    Optical pumping by blackbody radiation is a feature shared by all polar molecules and fundamentally limits the time that these molecules can be kept in a single quantum state in a trap. To demonstrate and quantify this, we have monitored the optical pumping of electrostatically trapped OH and OD radicals by room-temperature blackbody radiation. Transfer of these molecules to rotationally excited states by blackbody radiation at 295 K limits the 1/e1/e trapping time for OH and OD in the X2Π3/2,v′′=0,J′′=3/2(f)X^{2}\Pi_{3/2},v''=0,J''=3/2(f) state to 2.8 s and 7.1 s, respectively.Comment: corrected small mistakes; added journal reference
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