25 research outputs found

    UV line diagnostics of accretion disk winds in cataclysmic variables

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    The IUE data base is used to analyze the UV line shapes of cataclysmic variables RW Sex, RW Tri, and V Sge. Observed lines are compared to synthetic line profiles computed using a model of rotating bi-conical winds from accretion disks. The wind model calculates the wind ionization structure self-consistently including photoionization from the disk and boundary layer and treats 3-D line radiation transfer in the Sobolev approximation. It is found that winds from accretion disks provide a good fit for reasonable parameters to the observed UV lines which include the P Cygni profiles for low inclination systems and pure emission at large inclination. Disk winds are preferable to spherical winds which originate on the white dwarf because they (1) require a much lower ratio of mass loss rate to accretion rate and are therefore more plausible energetically, (2) provide a natural source for a bi-conical distribution of mass outflow which produces strong scattering far above the disk leading to P Cygni profiles for low inclination systems, and pure line emission profiles at high inclination with the absence of eclipses in UV lines, and (3) produce rotation broadened pure emission lines at high inclination

    Rotating Winds from Accretion Disks in Cataclysmic Variables: Eclipse Modeling of V347 Puppis

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    We study the eclipsing nova-like variable V347 Pup by matching its UV emission line profiles in and out of eclipse to synthetic lines using a 3D kinematic and radiation transfer model. Our results support the accretion disk origin of winds in non-magnetic CVs as opposite to the WD origin. Our main point concerns the importance of rotation for the UV emission line shapes in such systems. In particular, we show that the narrowing of the UV emission lines in V347 Pup during eclipse can be easily explained by the eclipse of the innermost part of the wind by the secondary and the resulting reduction in the contribution of rotational broadening to the width of the lines. During the eclipse, the residual line flux is very sensitive to the maximal temperature of disk radiation. Good fits for reasonable mass-loss rates have been obtained for maximum disk temperatures of 50,000 degrees. This constraint was imposed either by leveling off the inner disk temperature profiles, in agreement with recent observations of some nova-like objects, or by assuming that the accretion disk does not extend to the surface of the white dwarf, in which case V347 up would be an intermediate polar. In anticipation of high-speed spectrophotometry of CVs by the HST, we provide numerical model of a time-resolved eclipse of V347 Pup or similar such system to be verified by future observations.Comment: x pages, postscrip, compressed uuencoded. 11 figures available by anonymous ftp from ftp://asta.pa.uky.edu/shlosman/puppis/ (get *.PS.Z). To appear in Ap

    Dynamics of Line-Driven Winds from Disks in Cataclysmic Variables. II. Mass Loss Rates and Velocity Laws

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    We analyze the dynamics of 2D stationary line-driven winds from accretion disks in cataclysmic variables (CVs), by generalizing the Castor, Abbott and Klein theory. In paper 1, we have solved the wind Euler equation, derived its two eigenvalues, and addressed the solution topology and wind geometry. Here, we focus on mass loss and velocity laws. We find that disk winds, even in luminous novalike variables, have low optical depth, even in the strongest driving lines. This suggests that thick-to-thin transitions in these lines occur. For disks with a realistic radial temperature, the mass loss is dominated by gas emanating from the inner decade in r. The total mass loss rate associated with a luminosity 10 Lsun is 10^{-12} Msun/yr, or 10^{-4} of the mass accretion rate. This is one order of magnitude below the lower limit obtained from P Cygni lines, when the ionizing flux shortwards of the Lyman edge is supressed. The difficulties with such small mass loss rates in CVs are principal, and confirm our previous work. We conjecture that this issue may be resolved by detailed nonLTE calculations of the line force within the context of CV disk winds, and/or better accounting for the disk energy distribution and wind ionization structure. We find that the wind velocity profile is well approximated by the empirical law used in kinematical modeling. The acceleration length scale is given by the footpoint radius of the wind streamline in the disk. This suggests an upper limit of 10 Rwd to the acceleration scale, which is smaller by factors of a few as compared to values derived from line fitting.Comment: 14 pages, 3 Postscript figures, also from http://www.pa.uky.edu/~shlosman/publ.html. Astrophysical Journal, submitte

    VIALACTEA knowledge base homogenizing access to Milky Way data

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    The VIALACTEA project has a work package dedicated to "Tools and Infrastructure" and, inside it, a task for the "Database and Virtual Observatory Infrastructure". This task aims at providing an infrastructure to store all the resources needed by the, more purposely, scientific work packages of the project itself. This infrastructure includes a combination of: storage facilities, relational databases and web services on top of them, and has taken, as a whole, the name of VIALACTEA Knowledge Base (VLKB). This contribution illustrates the current status of this VLKB. It details the set of data resources put together; describes the database that allows data discovery through VO inspired metadata maintenance; illustrates the discovery, cutout and access services built on top of the former two for the users to exploit the data content

    “A Massive Long Way”: Interconnecting Histories, a “Special Child,” ADHD, and Everyday Family Life

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    Focusing on one family from a study of dual-earner middle-class families carried out in Los Angeles, California, this article draws on interview and video-recorded data of everyday interactions to explore illness and healing as embedded in the microcultural context of the Morris family. For this family, an important aspect of what is at stake for them in their daily lives is best understood by focusing on 9-year-old Mark, who has been diagnosed with attention-deficit/hyperactivity disorder (ADHD). In this article, we grapple with the complexity of conveying some sense of how Mark’s condition is experienced and relationally enacted in everyday contexts. Through illuminating connections between lives as lived and lives as told, we explore the narrative structuring of healing in relation to Mark’s local moral world with the family at its center. We examine how his parents understand the moral consequences of the child’s past for his present and future, and work to encourage others to give due weight to his troubled beginnings before this child joined the Morris family. At the same time, we see how the Morris parents act to structure Mark’s moral experience and orient to a desired future in which Mark’s “success” includes an appreciation of how he is accountable to others for his actions. Through our analyses, we also seek to contribute to discussions on what is at stake in everyday life contexts for children with ADHD and their families, through illuminating aspects of the cultural, moral and relational terrain that U.S. families navigate in contending with a child’s diagnosis of ADHD. Further, given that ADHD is often construed as a “disorder of volition,” we seek to advance anthropological theorizing about the will in situations where volitional control over behavior is seen to be disordered

    Analytic Model of Reactive Flow Analytic Model of Reactive Flow

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    Abstract A simple analytic model allows prediction of rate constants and size effect behavior before a hydrocode run if size effect data exists. At infinite radius, it defines not only detonation velocity but also average detonation rate, pressure and energy. This allows the derivation of a generalized radius, which becomes larger as the explosive becomes more non-ideal. The model is applied to near-ideal PBX 9404, in-between ANFO and most non-ideal AN. The power of the pressure declines from 2.3, 1.5 to 0.8 across this set. The power of the burn fraction, F, is 0.8, 0 and 0, so that an F-term is important only for the ideal explosives. The size effect shapes change from concave-down to nearly straight to concave-up. Failure is associated with ideal explosives when the calculated detonation velocity turns in a double-valued way. The effect of the power of the pressure may be simulated by including a pressure cutoff in the detonation rate. The models allows comparison of a wide spectrum of explosives providing that a single detonation rate is feasible

    Bacterial identification by dot blot hybridization

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    The vast amount of bacteria and difficulty in their culturability has impeded progress in classifying and identifying these many unknown species. The purpose of this project was to develop a micro-array blot system to determine the presence and eventually the relative amounts of bacteria in virtually any environment. A hybridization protocol was developed here using florescent (6-FAM) tagged, oligonucleotide probes with fully extracted samples of ribosomal RNA from Proteobacteria of the alpha, beta and gamma sub-classes

    Developing Content for an Interprofessional Training on Fear of Cancer Recurrence (FCR): Key Informant Interviews of Healthcare Professionals, Researchers and Cancer Survivors

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    Background: Growing numbers of cancer survivors are receiving healthcare through primary care practitioners, who often lack cancer-specific expertise to effectively treat survivors’ concerns. Addressing that gap, this study aimed to develop content for a training on fear of cancer recurrence (FCR), a common concern in survivorship. Methods: Grounded in naturalistic inquiry, 42 key-informant interviews were conducted, transcribed, and analyzed for themes. Participants were healthcare professionals, researchers, and cancer survivors Results: Results included themes ranging from: rich conceptualizations of FCR, opportunities and challenges for addressing FCR in healthcare settings, interventions to address FCR, and important information to include in a training on FCR. Conclusions: This paper provides content for an interprofessional training and highlights the importance of developing trainings for interprofessional teams, given identified barriers that physicians face in addressing FCR and other psychosocial concerns of survivors in primary care
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