First Results from MASIV: The Micro-Arcsecond Scintillation-Induced Variability Survey

We are undertaking a large-scale, Micro-Arcsecond Scintillation-Induced Variability (MASIV) survey of the northern sky, Dec > 0 deg, at 4.9 GHz with the VLA. Our objective is to construct a sample of 100 to 150 scintillating extragalactic sources with which to examine both the microarcsecond structure and the parent populations of these sources, and to probe the turbulent interstellar medium responsible for the scintillation. We report on our first epoch of observations which revealed variability on timescales ranging from hours to days in 85 of 710 compact flat-spectrum sources. The number of highly variable sources, those with RMS flux density variations greater than 4% of the mean, increases with decreasing source flux density but rapid, large amplitude variables such as J1819+3845 are very rare. When compared with a model for the scintillation due to irregularities in a 500 pc thick electron layer, our preliminary results indicate maximum brightness temperatures ~10E+12 K, similar to those obtained from VLBI surveys even though interstellar scintillation is not subject to the same angular resolution limit.Comment: 18 pages, 5 figures. To appear in the Astronomical Journa

Simulating Electron Transport and Synchrotron Emission in Radio Galaxies: Shock Acceleration and Synchrotron Aging in Axis-Symmetric Flows

We introduce a simple and economical but effective method for including relativistic electron transport in multi-dimensional simulations of radio galaxies. The method is designed to follow explicitly diffusive acceleration at shocks, and, in smooth flows 2nd order Fermi acceleration plus adiabatic and synchrotron cooling. We are able to follow both the spatial and energy distributions of the electrons, so that direct synchrotron emission properties can be modeled in time-dependent flows for the first time. Here we present first results in the form of some axis-symmetric MHD simulations of Mach 20 light jet flows. These show clearly the importance of nonsteady terminal shocks that develop in such flows even when the jet inflow is steady. As a result of this and other consequences of the fundamentally driven character of jets, we find complex patterns of emissivities and synchrotron spectra, including steep spectral gradients in hot spots, islands of distinct spectra electrons within the lobes and spectral gradients coming from the dynamical histories of a given flow element rather than from synchrotron aging of the embedded electrons. In addition, spectral aging in the lobes tends to proceed more slowly than one would estimate from regions of high emissivity.Comment: 30 pages of Latex generated text plus 7 figures in gif format. Accepted for publication in the Astrophysical Journal. High resolution postscript figures available through anonymous ftp at ftp://ftp.msi.umn.edu/pub/users/twj/RGje

Assessment of Trace Estrogenic Contaminants Removal by Coagulant Addition, Powdered Activated Carbon Adsorption and Powdered Activated Carbon/Microfiltration Processes

Increasing attention is being paid to health and environmental risk as a result of the presence of trace steroid estrogens in the effluent discharged from municipal sewage treatment plants. This paper focuses on assessment of removal of these trace compounds using 3H-labelled estrone as the model compound. Jar tests over a range of ferric chloride dosage and pH conditions showed that coagulation was ineffective in removal of estrone from secondary effluent. The experiments showed that the combination of PAC and microfiltration could be effective for removal of trace estrone from water. The rate and extent of estrone removal by PAC are functions of PAC dosage and retention time of PAC in the system. Mathematical analysis of the results using a homogeneous surface diffusion model (HSMD) indicates that the adsorption of estrone on PAC can be limited by film diffusion and internal surface diffusion. The surface and film mass transfer coefficients were determined to be 9.72 x 10-10 cm2/min and 1.963 cm/min, respectively, under the conditions used

The "Artificial Mathematician" Objection: Exploring the (Im)possibility of Automating Mathematical Understanding

Reuben Hersh confided to us that, about forty years ago, the late Paul Cohen predicted to him that at some unspecified point in the future, mathematicians would be replaced by computers. Rather than focus on computers replacing mathematicians, however, our aim is to consider the (im)possibility of human mathematicians being joined by “artificial mathematicians” in the proving practice—not just as a method of inquiry but as a fellow inquirer

Language and theory of mind in autism spectrum disorder : the relationship between complement syntax and false belief task performance.

This study aimed to test the hypothesis that children with autism spectrum disorder (ASD) use their knowledge of complement syntax as a means of “hacking out” solutions to false belief tasks, despite lacking a representational theory of mind (ToM). Participants completed a “memory for complements” task, a measure of receptive vocabulary, and traditional location change and unexpected contents false belief tasks. Consistent with predictions, the correlation between complement syntax score and location change task performance was significantly stronger within the ASD group than within the comparison group. However, contrary to predictions, complement syntax score was not significantly correlated with unexpected contents task performance within either group. Possible explanations for this pattern of results are considered

Conflation and refutation: Book review of T. Uller and K. N. Laland. eds. 2019. Evolutionary causation: biological and philosophical Reflections. MIT Press, Cambridge, MA. 352: pp. ISBN: 978‐0‐262‐03992‐5. $60.00/£50.00

Evolutionary Causation, the new edited book from Tobias Uller and Kevin Laland (Uller and Laland, 2019) should be seen as a positive contribution to those seeking an Extended Evolutionary Synthesis (EES). The ambition for an EES has emerged most vociferously over the past 15 years, but its antecedents stretch back to the key work in the 1970s of Gould, Lewontin and their colleagues. At root arguments for an EES are arguments about how the Modern Synthesis (MS) in evolutionary biology has been found wanting. Much of this discontent has been to do with theoreticians rethinking concepts of adaptation, inheritance and development (Jablonka and Lamb, 2006; Huneman and Walsh, 2017) as well as variation and macroevolution (Pigliucci and Muller, 2010). This book continues this work, but focuses on analysis of the central concept of causation within evolution

Primordialists and Constructionists: a typology of theories of religion

This article adopts categories from nationalism theory to classify theories of religion. Primordialist explanations are grounded in evolutionary psychology and emphasize the innate human demand for religion. Primordialists predict that religion does not decline in the modern era but will endure in perpetuity. Constructionist theories argue that religious demand is a human construct. Modernity initially energizes religion, but subsequently undermines it. Unpacking these ideal types is necessary in order to describe actual theorists of religion. Three distinctions within primordialism and constructionism are relevant. Namely those distinguishing: a) materialist from symbolist forms of constructionism; b) theories of origins from those pertaining to the reproduction of religion; and c) within reproduction, between theories of religious persistence and secularization. This typology helps to make sense of theories of religion by classifying them on the basis of their causal mechanisms, chronology and effects. In so doing, it opens up new sightlines for theory and research

The narrative self, distributed memory, and evocative objects

In this article, I outline various ways in which artifacts are interwoven with autobiographical memory systems and conceptualize what this implies for the self. I first sketch the narrative approach to the self, arguing that who we are as persons is essentially our (unfolding) life story, which, in turn, determines our present beliefs and desires, but also directs our future goals and actions. I then argue that our autobiographical memory is partly anchored in our embodied interactions with an ecology of artifacts in our environment. Lifelogs, photos, videos, journals, diaries, souvenirs, jewelry, books, works of art, and many other meaningful objects trigger and sometimes constitute emotionally-laden autobiographical memories. Autobiographical memory is thus distributed across embodied agents and various environmental structures. To defend this claim, I draw on and integrate distributed cognition theory and empirical research in human-technology interaction. Based on this, I conclude that the self is neither defined by psychological states realized by the brain nor by biological states realized by the organism, but should be seen as a distributed and relational construct

Learning From Early Attempts to Generalize Darwinian Principles to Social Evolution

Copyright University of Hertfordshire & author.Evolutionary psychology places the human psyche in the context of evolution, and addresses the Darwinian processes involved, particularly at the level of genetic evolution. A logically separate and potentially complementary argument is to consider the application of Darwinian principles not only to genes but also to social entities and processes. This idea of extending Darwinian principles was suggested by Darwin himself. Attempts to do this appeared as early as the 1870s and proliferated until the early twentieth century. But such ideas remained dormant in the social sciences from the 1920s until after the Second World War. Some lessons can be learned from this earlier period, particularly concerning the problem of specifying the social units of selection or replication

Digital Propaganda: The Tyranny of Ignorance

© The Author(s) 2018. The existence of propaganda is inexorably bound to the nature of communication and communications technology. Mass communication by citizens in the digital age has been heralded as a means to counter elite propaganda; however, it also provides a forum for misinformation, aggression and hostility. The extremist group Britain First has used Facebook as a way to propagate hostility towards Muslims, immigrants and social security claimants in the form of memes, leading to a backlash from sites antithetical to their message. This article provides a memetic analysis, which addresses persuasion, organisation, political echo chambers and self-correcting online narratives; arguing that propaganda can be best understood as an evolving set of techniques and mechanisms which facilitate the propagation of ideas and actions. This allows the concept to be adapted to fit a changing political and technological landscape and to encompass both propaganda and counter-propaganda in the context of horizontal communications networks