An intuitive handheld acoustic noise source finder

ABSTRACT - An apparatus has been developed to find acoustic sound sources in the near field of a radiating object operating in a noisy environment. It is based on two orthogonally placed particle velocity probes (two Microflowns[1], [2]). The complete signal processing is done in real time with battery powered analogue circuitry, resulting in a very small and handheld measurement device. One Microflown is used to display the sound level and to listen to the source whilst rejecting the background noise and another Microflown is used to create a stereo\ud indication in which direction the device must be moved to pinpoint the noise source

Multiscale image analysis applied to gamma/hadron discrimination for VHE gamma-ray astronomy with ARGO-YBJ

Intrinsic differences in the processes involved in the development of electromagnetic and hadronic showers in the atmosphere have been evidenced by means of a careful analysis of the event image given by the ARGO-YBJ detector. The images have been analyzed at different length scales and their multifractal nature has been studied. The use of the multiscale approach together with a properly designed and trained Artificial Neural Network, allowed us to obtain a good gamma/hadron discrimination power. If confirmed by further studies on different event cathegories, this result would allow to nearly double the detector sensitivity to gamma ray sources.Comment: 10 pages, 5 figures, Presented at the "Incontro Nazionale di Astrofisica delle Alte Energie", Rome 15-16 May 200

An e-class in action: Experiences with ICT-intensive teaching and learning of discrete dynamical models at secondary school

In 2007, a small team of university and secondary school mathematics teachers jointly developed and piloted an e-class for 4th and 5th grade students (age: 16-17yrs) at both pre-university and general vocational level. The goal was to develop and try out innovative ways of teaching mathematics that would enable schools to offer optional courses for small numbers of students. The e-class can be summarized as web-supported instruction in a blended learning approach. The instructional material consisted of the chapter on discrete dynamical models from a brand-new mathematics textbook, supplemented by investigative activities. Students could build and simulate dynamical models with the computer learning environment Coach. Instructions for learning to work with software were given through screen casts created by the teacher to gear with students' needs and made available in the Sakai-based virtual learning environment. Students got weekly on-line assignments, which they submitted digitally. At home they could get assistance from peers and the teacher in a chat room. The authors discuss some of the e-ingredients of the e-class and their potential for teaching and learning mathematics and science in terms of principled design approaches to multimedia learning and pedagogical arrangements. The authors report the experiences of the participants of the project and present the future plans based on this work

Spectroscopic study of the O-type runaway supergiant HD 195592

The scope of this paper is to perform a detailed spectroscopic study of the northern O-type supergiant HD 195592. We use a large sample of high quality spectra in order to investigate its multiplicity, and to probe the line profile variability. Our analysis reveals a clear spectroscopic binary signature in the profile of the He {\sc i} $\lambda$ 6678 line, pointing to a probable O + B system. We report on low amplitude radial velocity variations in every strong absorption line in the blue spectrum of HD 195592. These variations are ruled by two time-scales respectively of 5.063 and about 20 days. The former is firmly established, whilst the latter is poorly constrained. We report also on a very significant line profile variability of the H $\beta$ line, with time scales strongly related to those of the radial velocities. Our results provide significant evidence that HD 195592 is a binary system, with a period that might be the variability time-scale of about 5 days. The second time scale may be the signature of an additional star moving along a wider orbit provided its mass is low enough, even though direct evidence for the presence of a third star is still lacking. Alternatively, the second time-scale may be the signature of a variability intrinsic to the stellar wind of the primary, potentially related to the stellar rotation.Comment: 9 pages, 5 postscript figures, accepted for publication in New Astronom