47,554 research outputs found
The Probable Detection of SN 1923A: The Oldest Radio Supernova?
Based upon the results of VLA observations, we report the detection of two
unresolved radio sources that are coincident with the reported optical position
of SN 1923A in M83. For the source closest to the SN position, the flux density
was determined to be 0.30 +/- 0.05 mJy at 20 cm and 0.093 +/- 0.028 mJy at 6
cm. The flux density of the second nearby source was determined to be 0.29 +/-
0.05 at 20 cm and 0.13 +/- 0.028 at 6 cm. Both sources are non-thermal with
spectral indices of alpha = -1.0 +/- 0.30 and -0.69 +/- 0.24, respectively. SN
1923A has been designated as a Type II-P. No Type II-P (other than SN 1987A)
has been detected previously in the radio. The radio emission from both sources
appears to be fading with time. At an age of approximately 68 years when we
observed it, this would be the oldest radio supernova (of known age) yet
detected
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The contributions of domain-general and numerical factors to third-grade arithmetic skills and mathematical learning disability
Explanations of the marked individual differences in elementary school mathematical achievement and mathematical learning disability (MLD or dyscalculia) have involved domain-general factors (working memory, reasoning, processing speed and oral language) and numerical factors that include single-digit processing efficiency and multi-digit skills such as number system knowledge and estimation. This study of third graders (N = 258) finds both domain-general and numerical factors contribute independently to explaining variation in three significant arithmetic skills: basic calculation fluency, written multi-digit computation, and arithmetic word problems. Estimation accuracy and number system knowledge show the strongest associations with every skill and their contributions are both independent of each other and other factors. Different domain-general factors independently account for variation in each skill. Numeral comparison, a single digit processing skill, uniquely accounts for variation in basic calculation. Subsamples of children with MLD (at or below 10th percentile, n = 29) are compared with low achievement (LA, 11th to 25th percentiles, n = 42) and typical achievement (above 25th percentile, n = 187). Examination of these and subsets with persistent difficulties supports a multiple deficits view of number difficulties: most children with number difficulties exhibit deficits in both domain-general and numerical factors. The only factor deficit common to all persistent MLD children is in multi-digit skills. These findings indicate that many factors matter but multi-digit skills matter most in third grade mathematical achievement
The state of MIIND
MIIND (Multiple Interacting Instantiations of Neural Dynamics) is a highly modular multi-level C++ framework, that aims to shorten the development time for models in Cognitive Neuroscience (CNS). It offers reusable code modules (libraries of classes and functions) aimed at solving problems that occur repeatedly in modelling, but tries not to impose a specific modelling philosophy or methodology. At the lowest level, it offers support for the implementation of sparse networks. For example, the library SparseImplementationLib supports sparse random networks and the library LayerMappingLib can be used for sparse regular networks of filter-like operators. The library DynamicLib, which builds on top of the library SparseImplementationLib, offers a generic framework for simulating network processes. Presently, several specific network process implementations are provided in MIIND: the WilsonâCowan and OrnsteinâUhlenbeck type, and population density techniques for leaky-integrate-and-fire neurons driven by Poisson input. A design principle of MIIND is to support detailing: the refinement of an originally simple model into a form where more biological detail is included. Another design principle is extensibility: the reuse of an existing model in a larger, more extended one. One of the main uses of MIIND so far has been the instantiation of neural models of visual attention. Recently, we have added a library for implementing biologically-inspired models of artificial vision, such as HMAX and recent successors. In the long run we hope to be able to apply suitably adapted neuronal mechanisms of attention to these artificial models
Nucleosynthesis Basics and Applications to Supernovae
This review concentrates on nucleosynthesis processes in general and their
applications to massive stars and supernovae. A brief initial introduction is
given to the physics in astrophysical plasmas which governs composition
changes. We present the basic equations for thermonuclear reaction rates and
nuclear reaction networks. The required nuclear physics input for reaction
rates is discussed, i.e. cross sections for nuclear reactions,
photodisintegrations, electron and positron captures, neutrino captures,
inelastic neutrino scattering, and beta-decay half-lives. We examine especially
the present state of uncertainties in predicting thermonuclear reaction rates,
while the status of experiments is discussed by others in this volume (see M.
Wiescher). It follows a brief review of hydrostatic burning stages in stellar
evolution before discussing the fate of massive stars, i.e. the nucleosynthesis
in type II supernova explosions (SNe II). Except for SNe Ia, which are
explained by exploding white dwarfs in binary stellar systems (which will not
be discussed here), all other supernova types seem to be linked to the
gravitational collapse of massive stars (M8M) at the end of their
hydrostatic evolution. SN1987A, the first type II supernova for which the
progenitor star was known, is used as an example for nucleosynthesis
calculations. Finally, we discuss the production of heavy elements in the
r-process up to Th and U and its possible connection to supernovae.Comment: 52 pages, 20 figures, uses cupconf.sty (included); to appear in
"Nuclear and Particle Astrophysics", eds. J. Hirsch., D. Page, Cambridge
University Pres
The Role of Father Involvement and Marital Satisfaction in the Development of Family Interactive Abilities: A Multilevel Approach.
The study aims to investigate the development of family interactions from pregnancy to preschool age in a longitudinal perspective, using multilevel analysis. Also, it explored the impact of couple relationship and father involvement in childcare on the developmental trend of the quality of mother\u2013father\u2013child interactions. One hundred and three primiparous families were assessed at 7th month of pregnancy, 4th, 9th, and 18th months of child\u2019s life and during preschool age (36\u201348th), using the observational procedure named, Lausanne Trilogue Play. Parents\u2019 perception of marital satisfaction was assessed with the Dyadic Adjustment Scale at each point of measure; moreover, in the postnatal assessment, parents completed the Father Involvement Questionnaire. Results showed that family interactions increase over time. Secondly, a decrease of marital adjustment is associated with an improvement of the quality of family interactions. Moreover, father involvement predicts the quality of family interactions from the earliest stages of child\u2019s life. In a longitudinal perspective, family interactions and marital quality show opposite developmental trends and father\u2019s involvement represents a particularly important feature of the family
CRISPR as a Driving Force: The Model T of Biotechnology
The CRISPR system for gene editing can break, repair, and replace targeted sections of DNA. Although CRISPR gene editing has important therapeutic potential, it raises several ethical concerns. Some bioethicists worry CRISPR is a prelude to a dystopian future, while others maintain it should not be feared because it is analogous to past biotechnologies. In the scientific literature, CRISPR is often discussed as a revolutionary technology. In this paper we unpack the framing of CRISPR as a revolutionary technology and contrast it with framing it as a value-threatening biotechnology or business-as-usual. By drawing on a comparison between CRISPR and the Ford Model T, we argue CRISPR is revolutionary as a product, process, and as a force for social change. This characterization of CRISPR offers important conceptual clarity to the existing debates surrounding CRISPR. In particular, conceptualizing CRISPR as a revolutionary technology structures regulatory goals with respect to this new technology. Revolutionary technologies have characteristic patterns of implementation, entrenchment, and social impact. As such, early identification of technologies as revolutionary may help construct more nuanced and effective ethical frameworks for public policy
The Influence of Regret Proneness, Evidence Strengthening, and Perceived Responsibility on Verdict Preference
In the present study, we investigated perceived responsibility, evidence strengthening, and defendant gender in the context of a criminal trial involving DNA. Evidence was introduced post-trial and varied as strengthening the defendantâs guilt v. innocence. We also examined perceptions of perceived responsibility for verdict in order to more closely evaluate the role of regret in decision-making. Results indicated that DNA evidence is perceived as reliable, regardless of whether it strengthened guilt or innocence. In addition, greater confidence in verdict was observed when evidence strengthened the guilt of a female defendant vs. a male defendant. Finally, jurors experiencing high levels of regret perceived DNA evidence more selectively compared to jurors with low levels of regret, supporting the importance of identifying individual difference factors prior to trial
Trickery, Mockery and the Scottish Way of War
This article seeks to examine two prominent themes, those of trickery and mockery, in how warfare against England was represented in Scottish historical narratives of the fourteenth and fifteenth centuries. Careful analysis of these specific themes allows a variety of insights to be presented. It will show some of the rich uses to which such texts can be put by exploring them in a historically informed context. One aspect of this is the endeavour to illuminate ways in which these sources, although treacherous in relation to specifics, can provide accurate, and previously unnoticed, more general insights into the cultures of war embraced by the Scots. Analysis of the texts also demonstrates the complex and changing ways in which perceptions about the practice of war have shaped Scottish senses of identity. It becomes clear that ideas about their mode of war were vital in how the Scots saw themselves. And such ideas were also fundamental in shaping the much more hostile view of them developed by their regular enemies, the English. The main sources given consideration are the Gesta Annalia II, once attributed to John of Fordun (composed c1363) (Chron Fordun)1
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