Search results for "COD"
showing 10 items of 2985 documents
Analyzing the Contextual Nature of Collaborative Activity
2010
This chapter discusses a methodology designed to explore the contextual nature of collaborative activity. The methods that can be generally considered to be based on ‘socio-cultural’ discourse analysis are discussed as a means to explore how different aspects of a situation mediate students’ shared meaning-making. First, an analysis is demonstrated, illustrating how different immediate and mediated contexts are embedded in students’ discourse as they are engaged in face-to-face collaborative activity in a computer-mediated context. Second, a multidimensional coding scheme is presented for analyzing the contextualized process of collaborative knowledge construction in an asynchronous web-ba…
Using knowledge of human-generated code to bias the search in program synthesis with grammatical evolution
2021
Recent studies show that program synthesis with GE produces code that has different structure compared to human-generated code, e.g., loops and conditions are hardly used. In this article, we extract knowledge from human-generated code to guide evolutionary search. We use a large code-corpus that was mined from the open software repository service GitHub and measure software metrics and properties describing the code-base. We use this knowledge to guide the search by incorporating a new selection scheme. Our new selection scheme favors programs that are structurally similar to the programs in the GitHub code-base. We find noticeable evidence that software metrics can help in guiding evoluti…
DNA traces the origin of honey by identifying plants, bacteria and fungi
2021
The regional origin of a food product commonly affects its value. To this, DNA-based identification of tissue remains could offer fine resolution. For honey, this would allow the usage of not only pollen but all plant tissue, and also that of microbes in the product, for discerning the origin. Here we examined how plant, bacterial and fungal taxa identified by DNA metabarcoding and metagenomics differentiate between honey samples from three neighbouring countries. To establish how the taxonomic contents of honey reflect the country of origin, we used joint species distribution modelling. At the lowest taxonomic level by metabarcoding, with operational taxonomic units, the country of origin …
Enseñanza de las ciencias : revista de investigación y experiencias didácticas
2021
Se expone el proceso seguido por un equipo de docentes de secundaria con el objetivo de cambiar la metodología de trabajo en el aula mediante el diseño y aplicación de una secuencia de aprendizaje definida a partir del aprendizaje basado en retos que integre de manera interdisciplinar los contenidos de Biología y Geografía en segundo de la ESO. Mediante la reflexión didáctica compartida, organizada y continuada se transforma una salida de campo tradicional en un nuevo proyecto de trabajo que se desarrolla a lo largo de un trimestre completo. Los resultados muestran la nueva secuencia de actividades creada, la percepción de los estudiantes y familias y los beneficios en la implicación del al…
Toward a model for students’ combinatorial thinking
2021
Abstract Combinatorics has many applications in different disciplines, however, only a few studies have explored students’ combinatorial thinking at the upper secondary and tertiary levels concurrently. The present research is a grounded theory study of eight Year 12 and five undergraduate students, who have participated in semi-structured interviews and responded to eight combinatorial tasks. Three types of combinatorial tasks were designed: combinatorial reasoning, evaluating, and problem-posing tasks. In the open coding phase of data analysis, seventy-one codes were identified which categorized into seven main categories at the axial coding phase. At the selective coding phase, five rela…
Bifurcations of Regular Limit Periodic Sets
1998
In this chapter, (X λ ) will be a smooth or analytic (in Section 3) family of vector fields on a phase space S, with parameter λ ∈ P, as in Chapter 1. Periodic orbits and elliptic singular points which are limits of sequences of limit cycles are called regular limit periodic sets. The reason for this terminology is that for such a limit periodic set Γ one can define local return maps on transversal segments, which are as smooth as the family itself. The limit cycles near Γ will be given by a smooth equation and the theory of bifurcations of limit cycles from Γ will reduce to the theory of unfoldings of differentiable functions. In fact, we will just need the Preparation Theorem and not the …
New insights into seismic absorption imaging
2020
Abstract In recent years, attenuation has been used as a marker for source and dynamic Earth processes due to its higher sensitivity to small variations of lithospheric properties compared to seismic velocity. From seismic hazard analysis to oil and gas exploration and rock physics, many fields need a better reconstruction of energy absorption, a constituent of seismic attenuation generally considered a reliable marker of fluid saturation in space. Here, we propose absorption tomography (AT), a technique grounded on the principles of scattering tomography and Multiple Lapse Time Window Analysis. We benchmark its efficiency to image absorption in space by comparing its results with those obt…
Understanding seismic path biases and magmatic activity at Mount St Helens volcano before its 2004 eruption
2020
SUMMARY In volcanoes, topography, shallow heterogeneity and even shallow morphology can substantially modify seismic coda signals. Coda waves are an essential tool to monitor eruption dynamics and model volcanic structures jointly and independently from velocity anomalies: it is thus fundamental to test their spatial sensitivity to seismic path effects. Here, we apply the Multiple Lapse Time Window Analysis (MLTWA) to measure the relative importance of scattering attenuation vs absorption at Mount St Helens volcano before its 2004 eruption. The results show the characteristic dominance of scattering attenuation in volcanoes at lower frequencies (3–6 Hz), while absorption is the primary atte…
On the Optimization of Self-Organizing Maps by Genetic Algorithms
1999
Publisher Summary This chapter reviews the research on the genetic optimization of self-organizing maps (SOMs). The optimization of learning rule parameters and of initial weights is able to improve network performance. The latter, however, requires chromosome sizes proportional to the size of the SOM and becomes unwieldy for large networks. The optimization of learning rule structures leads to self-organization processes of character similar to the standard learning rule. A particularly strong potential lies in the optimization of SOM topologies, which allows the study of global dynamical properties of SOMs and related models, as well as to develop tools for their analysis. Hierarchies of …
Threats to validity when using open-ended items in international achievement studies : Coding responses to the PISA 2012 problem-solving test in Finl…
2015
Open-ended (OE) items are widely used to gather data on student performance in international achievement studies. However, several factors may threaten validity when using such items. This study examined Finnish coders’ opinions about threats to validity when coding responses to OE items in the PISA 2012 problem-solving test. A total of 6 discussions during 6 coder practice sessions (on 6 OE items) and an interview between 5 coders were audiorecorded and analyzed by means of content analysis, and 3 main threats to validity were found: (1) unclear and complex questions; (2) arbitrary and illogical coding rubrics; and (3) unclear and ambiguous responses. Suggestions are given as to how to res…