150 research outputs found
Students’ use of digital scaffolding at University level: emergence of utilization schemes
No full textThis paper is focused on a pilot study involving a group of first year engineering students and concerning the design and implementation of two digital tasks on multiple representations of subsets of the plane. The tasks were engineered in order to provide university students with hints and feedback aimed at scaffolding their work. The analysis of the video-recordings of the students’ screens while interacting with the tasks, supported by the reflections developed by students during audio-recorded interviews after the activity, enabled us to highlight utilization schemes that characterize students’ use of digital tools for scaffolding their learning. We will also discuss how this analysis gave us suggestions for a future re-design of the tasks
Metis aboard the Solar Orbiter space mission: Doses from galactic cosmic rays and solar energetic particles
No full textWAVELET ANALYSIS AS A TOOL TO LOCALIZE MAGNETIC AND CROSS-HELICITY EVENTS IN THE SOLAR WIND
No full textIn this paper, we adopt the use of the wavelet transform as a new tool to investigate the time behavior at different scales of reduced magnetic helicity, cross-helicity, and residual energy in space plasmas. The main goal is a better characterization of the fluctuations in which interplanetary flux ropes are embedded. This kind of information is still missing in the present literature, and our tool can represent the basis for a new treatment of in situ measurements of this kind of event. There is a debate about the origins of small-scale flux ropes. It has been suggested that they are formed through magnetic reconnection in the solar wind, such as across the heliospheric current sheet. On the other hand, it has also been suggested that they are formed in the corona, similar to magnetic clouds. Thus, it looks like that there are two populations, one originating in the solar wind via magnetic reconnection across the current sheet in the inner heliosphere and the other originating in the corona. Small-scale flux ropes might be the remnants of the streamer belt blobs formed from disconnection; however, a one-to-one observation of a blob and a small-scale flux rope in the solar wind has yet to be found. Within this panorama of possibilities, this new technique appears to be very promising in investigating the origins of these objects advected by the solar wind
Solar Wind Magnetic Field Background Spectrum from Fluid to Kinetic Scales
No full textDuring solar activity minima, the solar wind is highly structured in fast and slow wind flows. These two dynamical regimes remarkably differ not only for average magnetic field and plasma values but also for the type of fluctuations they transport. Fast wind is characterized by large amplitude, incompressible fluctuations, mainly Alfvénic, slow wind is generally populated by smaller amplitude and less Alfvénic fluctuations, mainly compressive. Moving from fast to slow wind, along the speed profile of a high velocity stream, we observe the following behavior:a) the power level of magnetic field fluctuations within the inertial range largely decreases, keeping the typical Kolmogorov scaling;b) at proton scales, for about one decade, right beyond the high frequency break generally corresponding to the location of the ion-cyclotron resonance condition, the spectral index becomes flatter and flatter towards a value of -2.7, typically found in literature;c) at higher frequencies, before the electron scales, the spectral index remains around -2.7 and the power level does not change showing to be irrespective of the flow speed. This behavior is typically encountered during quiet solar activity conditions and suggests the existence of a sort of magnetic field background spectrum. Then, an Alfvènic spectrum would be added to this background any time the observer would enter and cross a fluxtube channeling the fast wind into the interplanetary space. Several example, in the limits of the available data, will be reported and the corresponding spectra from different epochs and source regions will be compared
LISA Pathfinder test-mass charging during galactic cosmic-ray flux short-term variations
No full textMetal free-floating test masses aboard the future interferometers devoted to gravitational wave detection in space are charged by galactic and solar cosmic rays with energies > 100 MeV/n. This process represents one of the main sources of noise in the lowest frequency band (< 10(-3) Hz) of these experiments. We study here the charging of the LISA Pathfinder (LISA-PF) gold-platinum test masses due to galactic cosmic-ray (GCR) protons and helium nuclei with the Fluka Monte Carlo toolkit. Projections of the energy spectra of GCRs during the LISA-PF operations in 2015 are considered. This work was carried out on the basis of the solar activity level and solar polarity epoch expected for LISA-PF. The effects of GCR short-term variations are evaluated here for the first time. Classical Forbush decreases, GCR variations induced by the Sun rotation, and fluctuations in the LISA-PF frequency bandwidth are discussed
GCR flux 9-day variations with LISA Pathfinder
No full textGalactic cosmic-ray (GCR) energy spectra in the heliosphere vary on the basis of the level of solar activity, the status of solar polarity and interplanetary transient magnetic structures of solar origin. A high counting rate particle detector (PD) aboard LISA Pathfinder (LPF) allows for the measurement of galactic cosmic-ray and solar energetic particle (SEP) integral fluxes at energies > 70 MeV n(-1) up to 6500 counts s(-1). Data are gathered with a sampling time of 15 s. A study of GCR flux depressions associated with the third harmonic of the Sun rotation period (similar to 9 days) is presented here
On teaching of word problems in the context of early algebra
No full textThis study reports a project on teaching word problems in early algebra for primary and lower secondary students. The word problems approach consisted of a set of connected activities in which problem solving, argumentation and problem posing were infused. The project aims to promote in students, within the usual classroom activities, inquiry attitude in problem solving, and awareness of the emerging mathematical objects. It engages them in argumentation activities to justify mathematical properties and in modelling processes. Results of one of the experiments of the project in a class of 5th grade students are reported. Within this study, we aim to: (a) orient the students to make argumentations of a solving process in general terms, (b) facilitate them to explore the corresponding numerical expressions for different series of numerical data, and (c) engage them in solving new questions that arise during their activities. The viability of the project is discussed in light of the results of the experimentation. The chapter is concluded with suggestions for the research and reflections on the teacher’s role in such a problem solving approach
PROMOTING FORMATIVE ASSESSMENT IN MATHEMATICS TEACHER EDUCATION: AN EXPERIENCE OF DISTANCE TEACHING
No full textWe discuss a distance teaching-learning approach, developed within two courses for prospective mathematics teachers, exploiting digital technologies to activate formative assessment practices. In particular, we analyse excerpts, from synchronous and asynchronous activities within the courses, to highlight the formative assessment processes that were activated, the feedback provided by prospective teachers to each other and their meta-reflections that testify learning in the domain of teacher education
Interplanetarymedium monitoring with LISA: Lessons from LISA Pathfinder
No full textThe Laser Interferometer Space Antenna (LISA) of the European Space Agency (ESA) will be the first low-frequency gravitational-wave observatory orbiting the Sun at 1 AU. The LISA Pathfinder (LPF) mission, aiming at testing the instruments to be located on board the LISA spacecraft (S/C), hosted, among the others, fluxgate magnetometers and a particle detector as parts of a diagnostics subsystem. These instruments allowed us to estimate the magnetic and Coulomb spurious forces acting on the test masses that constitute the mirrors of the interferometer. With these instruments, we also had the possibility to study the galactic cosmic-ray short term-term variations as a function of the particle energy and the associated interplanetary disturbances. Platform magnetometers and particle detectors will also be placed on board each LISA S/C. This work reports on an empirical method that allowed us to disentangle the interplanetary and onboard-generated components of the magnetic field by using the LPF magnetometer measurements. Moreover, we estimate the number and fluence of solar energetic particle events expected to be observed with the ESA Next Generation Radiation Monitor during the mission lifetime. An additional cosmic-ray detector, similar to that designed for LPF, in combination with magnetometers, would permit to observe the evolution of recurrent and non-recurrent galactic cosmic-ray variations and associated increases of the Interplanetary Magnetic Field at the transit of high-speed solar wind streams and interplanetary counterparts of coronal mass ejections. The diagnostics subsystem of LISA makes this mission also a natural multi-point observatory for space weather science investigations
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