a b s t r a c tSegmentation of the seabed is addressed by exploiting the local angular backscatter acoustic responses of the bottom. The study is based on data collected at sea with an experimental front-scan sonar system (COSMOS -Project partially funded by the European Commission in the MAST III program -Contract n°MAS3-CT97-0090 -DG12 -ESCY). Data were recorded during a three day survey in the Mediterranean Sea in high variability sediment areas. The front-looking geometry of the COSMOS system enables the collection of the local angular responses of the bottom over a wide range of incidence angles. The angular responses are projected on a principal components basis and subsequently classified by means of a density-based cluster identification method. The resulting segmentation maps delineate properly homogeneous zones of the seafloor that are in agreement with the ground-truth information provided by samples collected at sea.
Science education in primary schools in Uruguay is still a pending task. Frequently, only biological science is taught in class. Often, activities are reduced either to look for information without experimentation, or to very guided hand-on activities with little space for actual research where results may differ from what is expected and new questions might come up. As a result, children have a partial and sometimes wrong concept of science. The idea of science as something distant from reality and ordinary life, holding absolute results and truth, is reinforced. A lot of research has been done in science didactics about the role of experimentation in order to improve scientific competences in the students. In this project we analyze the role of experimentation during the science class as well as the speech of the teacher in relation to his objectives and the planned didactic sequence. A qualitative methodology was used, through classroom observations and interviews with teachers. We chose a case study to inquire how the experiments are used in a science class and what is the role of experiments proposed by the teacher. To collect the data, recordings of classes were used and in-depth interviews were conducted with the teacher.
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