Parallel Implementation of the PHOENIX Generalized Stellar Atmosphere Program

We describe the parallel implementation of our generalized stellar atmosphere and NLTE radiative transfer computer program PHOENIX. We discuss the parallel algorithms we have developed for radiative transfer, spectral line opacity, and NLTE opacity and rate calculations. Our implementation uses a MIMD design based on a relatively small number of MPI library calls. We report the results of test calculations on a number of different parallel computers and discuss the results of scalability tests.Comment: To appear in ApJ, 1997, vol 483. LaTeX, 34 pages, 3 Figures, uses AASTeX macros and styles natbib.sty, and psfig.st

Limb Darkening and Planetary Transits II: Intensity profile correction factors for a grid of model stellar atmospheres

The ability to observe extrasolar planets transiting their stars has profoundly changed our understanding of these planetary systems. However, these measurements depend on how well we understand the properties of the host star, such as radius, luminosity and limb darkening. Traditionally, limb darkening is treated as a parameterization in the analysis, but these simple parameterizations are not accurate representations of actual center-to-limb intensity variations (CLIV) to the precision needed for interpreting these transit observations. This effect leads to systematic errors for the measured planetary radii and corresponding measured spectral features. We compute synthetic planetary transits using model stellar atmosphere CLIV and corresponding best-fit limb-darkening laws for a grid spherically symmetric model stellar atmospheres. From these light curves we measure the differences in flux as a function of the star's effective temperature, gravity, mass, and the inclination of the planet's orbit.Comment: 10 pages, 8 figures, submitted to AAS journals. Comments welcom

Neural endophenotypes of social behaviour in autism spectrum conditions

Autism is characterized by qualitative impairments in social interaction, communication, and stereotyped repetitive behaviors and/or restricted interests. Beyond these diagnostic criteria, autism is viewed as a neurodevelopmental condition with possibly several etiologies that manifest in complex patterns of atypical structural and functional brain development, cognition, and behavior. Despite the multidimensional nature of and substantial variation within the autism spectrum, impairments in social interaction remain among the most visible hallmarks of the condition. It is this profound developmental deficit in the social domain that makes autism a unique case in the field of social neuroscience. This chapter contributes to the dialogue amongst both the fields of autism research and social neuroscience by deliberately taking the stance of asking how we can understand more about the etiological mechanisms underlying social behavior in autism. It presents a multi-level overview of the literature on the behavioral, neural, and genetic underpinnings of social functioning in autism spectrum conditions (ASC). The main objective is to highlight the current state of the field regarding theory of mind/empathy difficulties in ASC, and then to suggest distinct candidate neural endophenotypes that can bridge the gap between social behavior and genetic mechanisms

Multi-variable translation equation which arises from homothety

In many regular cases, there exists a (properly defined) limit of iterations of a function in several real variables, and this limit satisfies the functional equation (1-z)f(x)=f(f(xz)(1-z)/z); here z is a scalar and x is a vector. This is a special case of a well-known translation equation. In this paper we present a complete solution to this functional equation in case f is a continuous function on a single point compactification of a 2-dimensional real vector space. It appears that, up to conjugation by a homogeneous continuous function, there are exactly four solutions. Further, in a 1-dimensional case we present a solution with no regularity assumptions on f.Comment: 15 page

Property as Control: The Case of Information

If heath policy makers\u27 wishes come true, by the end of the current decade the paper charts in which most of our medical information is currently recorded will be replaced by networked electronic health records ( EHRs ).[...] Like all computerized records, networked EHRs are difficult to secure, and the information in EHRs is both particularly sensitive and particularly valuable for commercial purposes. Sadly, the existing federal statute meant to address this problem, the Health Insurance Portability and Accountability Act of 1996 ( HIPAA ), is probably inadequate to the task.[...] Health law, privacy, and intellectual property scholars have all suggested that the river of information created by integrated, networked EHRs and other data systems must somehow be controlled, and many of these scholars have considered whether property might provide such control.[...] The Article\u27s principal thesis is that arguments over the control of rights in personal information test contemporary understandings of what property is and reveal fault lines in modern property theory. If property rights exist at all in dephysicalized, digitized information, those rights are unlikely to be consolidated in a single person, to operate in rem, to grant owners significant powers to exclude, or to be standardized--qualities that, in the eyes of some, are required of true property interests. Claims of ownership to personal information also raise questions about whether property is the right rhetorical frame in which to consider the problem of information that is deeply connected to people\u27s selves. Finally, propertization claims assume a closer connection between property and control than is either realistic or desirable in an interconnected world. It is likely that, at the end of the day, individuals will as a matter of policy be granted some rights to control some of their personal information, but those rights will not follow from anything in property\u27s nature. Part I introduces the control issues raised by EHRs specifically and by the collection of personal information more generally, and then examines the arguments for using property as a device to control information.[...] Part II explores the connection between the loss of control over information and concerns about the self. It questions whether property is the best frame in which to talk about medical and other personal information, i.e., whether, rhetorically, we should treat information about the self as a commodity. It questions also whether we can avoid a property frame.[...] Part III returns to the specific policy problems presented by EHRs and by personal information. A workable EHR policy will take account of a wide variety of values, issues, and interests. Incentives must be created to facilitate EHR adoption, standards must be set to insure interoperability, malpractice rules must be adjusted to accommodate new practices (not to mention new mistakes), and procedures must be developed to enable use of EHR data for public health purposes.[...] A workable policy for EHRs and for personal information will no doubt provide individuals some control rights. These rights might look, in the eyes of some, like property rights. But if control rights are granted, it will not be because property demands them, but because other considerations of health and public policy do. All this raises the question of when and whether property might ever provide the control that advocates of information-as-property desire. In a world of de-physicalization and digitization, ownership may not provide the kind of power that old-fashioned property rhetoric invokes. This state of affairs is not necessarily one to be lamented. The question of how power and control over information will be apportioned involves hard choices. But because property theory is itself deeply divided over the extent to which property provides control, property itself cannot determine how these choices should be made. Property may never have actually given owners as much control as the new adherents of property in information envision. Even if it did, in a world of increasing interconnection, it may be good to be reminded that power and control are themselves always shared