6,019 research outputs found
Discovery of a supernova associated with GRB 031203: SMARTS Optical-Infrared Lightcurves from 0.2 to 92 days
Optical and infrared monitoring of the afterglow site of gamma-ray burst
(GRB) 031203 has revealed a brightening source embedded in the host galaxy,
which we attribute to the presence of a supernova (SN) related to the GRB ("SN
031203"). We present details of the discovery and evolution of SN 031203 from
0.2 to 92 days after the GRB, derived from SMARTS consortium photometry in I
and J bands. A template type Ic lightcurve, constructed from SN 1998bw
photometry, is consistent with the peak brightness of SN 031203 although the
lightcurves are not identical. Differential astrometry reveals that the SN, and
hence the GRB, occurred less than 300 h_71^-1 pc (3-sigma) from the apparent
galaxy center. The peak of the supernova is brighter than the optical afterglow
suggesting that this source is intermediate between a strong GRB and a
supernova.Comment: 11 pages, 3 figures, submitted to ApJ Letter
Teachers' classroom feedback: still trying to get it right
This article examines feedback traditionally given by teachers in schools. Such feedback tends to focus on children's acquisition and retrieval of externally prescribed knowledge which is then assessed against mandated tests. It suggests that, from a sociocultural learning perspective, feedback directed towards such objectives may limit children's social development. In this article, I draw on observation and interview data gathered from a group of 27 9- to 10-year olds in a UK primary school. These data illustrate the children's perceived need to conform to, rather than negotiate, the teacher's feedback comments. They highlight the children's sense that the teacher's feedback relates to school learning but not to their own interests. The article also includes alternative examples of feedback which draw on children's own inquiries and which relate to the social contexts within which, and for whom, they act. It concludes by suggesting that instead of looking for the right answer to the question of what makes teachers' feedback effective in our current classrooms, a more productive question might be how a negotiation can be opened up among teachers and learners themselves, about how teachers' feedback could support children's learning most appropriately
Structured evaluation of virtual environments for special-needs education
This paper describes the development of a structured approach to evaluate experiential and communication virtual learning environments (VLEs) designed specifically for use in the education of children with severe learning difficulties at the Shepherd special needs school in Nottingham, UK. Constructivist learning theory was used as a basis for the production of an evaluation framework, used to evaluate the design of three VLEs and how they were used by students with respect to this learning theory. From an observational field study of student-teacher pairs using the VLEs, 18 behaviour categories were identified as relevant to five of the seven constructivist principles defined by Jonassen (1994). Analysis of student-teacher behaviour was used to provide support for, or against, the constructivist principles. The results show that the three VLEs meet the constructivist principles in very different ways and recommendations for design modifications are put forward
Stable States of Biological Organisms
A novel model of biological organisms is advanced, treating an organism as a
self-consistent system subject to a pathogen flux. The principal novelty of the
model is that it describes not some parts, but a biological organism as a
whole. The organism is modeled by a five-dimensional dynamical system. The
organism homeostasis is described by the evolution equations for five
interacting components: healthy cells, ill cells, innate immune cells, specific
immune cells, and pathogens. The stability analysis demonstrates that, in a
wide domain of the parameter space, the system exhibits robust structural
stability. There always exist four stable stationary solutions characterizing
four qualitatively differing states of the organism: alive state, boundary
state, critical state, and dead state.Comment: Latex file, 12 pages, 4 figure
Onto-CC: a web server for identifying Gene Ontology conceptual clusters
The Gene Ontology (GO) vocabulary has been extensively explored to analyze the functions of coexpressed genes. However, despite its extended use in Biology and Medical Sciences, there are still high levels of uncertainty about which ontology (i.e. Molecular Process, Cellular Component or Molecular Function) should be used, and at which level of specificity. Moreover, the GO database can contain incomplete information resulting from human annotations, or highly influenced by the available knowledge about a specific branch in an ontology. In spite of these drawbacks, there is a trend to ignore these problems and even use GO terms to conduct searches of gene expression profiles (i.e. expression + GO) instead of more cautious approaches that just consider them as an independent source of validation (i.e. expression versus GO). Consequently, propagating the uncertainty and producing biased analysis of the required gene grouping hypotheses. We proposed a web tool, Onto-CC, as an automatic method specially suited for independent explanation/validation of gene grouping hypotheses (e.g. coexpressed genes) based on GO clusters (i.e. expression versus GO). Onto-CC approach reduces the uncertainty of the queries by identifying optimal conceptual clusters that combine terms from different ontologies simultaneously, as well as terms defined at different levels of specificity in the GO hierarchy. To do so, we implemented the EMO-CC methodology to find clusters in structural databases [GO Directed acyclic Graph (DAG) tree], inspired on Conceptual Clustering algorithms. This approach allows the management of optimal cluster sets as potential parallel hypotheses, guided by multiobjective/multimodal optimization techniques. Therefore, we can generate alternative and, still, optimal explanations of queries that can provide new insights for a given problem. Onto-CC has been successfully used to test different medical and biological hypotheses including the explanation and prediction of gene expression profiles resulting from the host response to injuries in the inflammatory problem. Onto-CC provides two versions: Ready2GO, a precalculated EMO-CC for several genomes and an Advanced Onto-CC for custom annotation files (http://gps-tools2.wustl.edu/onto-cc/index.html)
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