Informal physics teaching for a better society: a mooc-based and context-driven experience on learning radioactivity

The general objective of teaching physics is to provide the learners with useful knowledge, in terms of both interdisciplinary scientific concepts and practical problem-solving skills. In this work, we report the experimental evidence, collected during a first year physics class in an upper secondary technical school, for the urgent necessity to adopt an informal and inquiry-based strategy to teach physics effectively, in particular to all those students living in degraded socio-economic environments. Within the pedagogical framework of "Learning by Doing" and the paradigm "Learning by Teaching", we have explored the benefits of the students' participation to an informal ICT-based and inquiry-driven learning experience about radioactivity. Subsequently, the same students attended, as scientific communicators, a national science exhibition where the majority of the secondary schools in the region presents their scientific exhibits. About three months after the participation to the scientific exhibition, the students answered to a questionnaire about radioactivity. Their answers have been analysed in comparison with those provided by a control group of students who attended a traditional lecture-based instruction. A significant improvement in the memorization of the main aspects concerning a radioactive decay, such as the definition of isotope, particle and electromagnetic radiation, the understanding of the radioactivity process at microscopic level, as well as a stronger view of the useful aspect of radioactivity in the everyday life have been definitely achieved by the students involved in this study

An Inquiry-based approach to the Franck-Hertz experiment

The practice of scientists and engineers is today exerted within interdisciplinary contexts, placed at the intersections of different research fields, including nanoscale science. The development of the required competences is based on an effective science and engineering instruction, which should be able to drive the students towards a deeper understanding of quantum mechanics fundamental concepts and, at the same time, strengthen their reasoning skills and transversal abilities. In this study we report the results of an inquiry-driven learning path experienced by a sample of 12 electronic engineering undergraduates engaged to perform the Franck-Hertz experiment. Before being involved in this experimental activity, the students received a traditional lecture-based instruction on the fundamental concepts of quantum mechanics, but their answers to an open-ended questionnaire, administered at the beginning of the inquiry activity, demonstrated that the acquired knowledge was characterized by a strictly theoretical vision of quantum science, basically in terms of an artificial mathematical framework having very poor connections with the real world. The Franck Hertz experiment was introduced to the students by starting from the problem of finding an experimental confirmation of the Bohr’s postulates asserting that atoms can absorb energy only in quantum portions. The whole activity has been videotaped and this allowed us to deeply analyse the student perception’s change about the main concepts of quantum mechanics. We have found that the active participation to this learning experience favored the building of cognitive links among student theoretical perceptions of quantum mechanics and their vision of quantum phenomena, within an everyday context of knowledge. Furthermore, our findings confirm the benefits of integrating traditional lecture-based instruction on quantum mechanics with learning experiences driven by inquiry-based teaching strategies

An inquiry-based approach to the Franck-Hertz experiment

The practice of scientists and engineers is today exerted within interdisciplinary contexts, placed at the intersections of different research fields, including nanoscale science. The development of the required competences is based on an effective science and engineering instruction, which should be able to drive the students towards a deeper understanding of quantum mechanics fundamental concepts and, at the same time, strengthen their reasoning skills and transversal abilities. In this study we report the results of an inquiry-driven learning path experienced by a sample of 12 electronic engineering undergraduates engaged to perform the Franck-Hertz experiment. Before being involved in this experimental activity, the students received a traditional lecture-based instruction on the fundamental concepts of quantum mechanics, but their answers to an open-ended questionnaire, administered at the beginning of the inquiry activity, demonstrated that the acquired knowledge was characterized by a strictly theoretical vision of quantum science, basically in terms of an artificial mathematical framework having very poor connections with the real world. The Franck Hertz experiment was introduced to the students by starting from the problem of finding an experimental confirmation of the Bohr’s postulates asserting that atoms can absorb energy only in quantum portions. The whole activity has been videotaped and this allowed us to deeply analyse the student perception’s change about the main concepts of quantum mechanics. We have found that the active participation to this learning experience favored the building of cognitive links among student theoretical perceptions of quantum mechanics and their vision of quantum phenomena, within an everyday context of knowledge. Furthermore, our findings confirm the benefits of integrating traditional lecture-based instruction on quantum mechanics with learning experiences driven by inquiry-based teaching strategies

Teacher professional development in the context of the “Open Discovery of STEM laboratories” project: Is the MOOC methodology suitable for teaching physics?

The "Open Discovery of STEM Laboratories" (ODL) project, funded by the European Erasmus+ KA2 program, was aimed at introducing the use of MOOCs in school curricula. In particular, it fostered teacher collaboration in creating and using micro-MOOCs for the inclusion of STEM (Science, Technology, Engineering and Mathematics) online remote or virtual laboratories in the everyday teaching practice. The project focused on teachers, educators and curriculum designers with the aim to strengthen their profile by supporting them to deliver high quality teaching practices and to adopt new methods and tools. Thanks to the project, in service and pre-service teachers had the opportunity to extend their knowledge about the inquiry-based science teaching approach, improve both digital skills and pedagogical competences, experience international collaborative work, explore attractive open education resources helpful to design creative lessons on STEM topics. In this contribution, we focus our attention on the results from the ODL teacher training in Italy, showing the valuable feedback collected by teachers on the impact of the ODL pedagogical approach on Physics education at secondary school, highlighting strengths and possible weaknesses of the proposed methodology. The feedback to the ODL experience provided by both teachers and students during the multiplier events, in the summer school and after the first pilot-studies in the classroom, was very positive. Experiencing micro-MOOCs' approach has been reported by the teachers as a very effective strategy for increasing students' motivation to learn physics more meaningfully. Thanks to the ODL methodology, student understanding of physics concepts has been achieved within a multidisciplinary learning context which also supports the development of transversal abilities, communication and reasoning skills. The ODL learning activities provided the students with the opportunity to develop a large range of complementary competencies, such as working in groups, interpreting and evaluating experimental data, designing models, facing and solving everyday problems, which are all very relevant in physics education

Enhancement of electron spin lifetime in GaAs crystals: the benefits of dichotomous noise

The electron spin relaxation process in n-type GaAs crystals driven by a fluctuating electric field is investigated. Two different sources of fluctuations are considered: (i) a symmetric dichotomous noise and (ii) a Gaussian correlated noise. Monte Carlo numerical simulations show, in both cases, an enhancement of the spin relaxation time by increasing the amplitude of the external noise. Moreover, we find that the electron spin lifetime versus the noise correlation time: (i) increases up to a plateau in the case of dichotomous random fluctuations, and (ii) shows a nonmonotonic behaviour with a maximum in the case of bulks subjected to a Gaussian correlated noise.Comment: 6 pages, 3 figure

EXTERNAL NOISE EFFECTS IN DOPED SEMICONDUCTORS OPERATING UNDER SUB-THZ SIGNALS

We study the noise-induced effects on the electron transport dynamics in low-doped n-type GaAs samples by using a Monte Carlo approach. The system is driven by an external periodic electric field in the presence of a random telegraph noise source. The modifications caused by the addition of external fluctuations are investigated by studying the spectral density of the electron velocity fluctuations for different values of the noise parameters. The findings indicate that the diffusion noise in low-doped semiconductors can be reduced by the addition of a fluctuating component to the driving electric field, but the effect critically depends on the features of the external noise source

Intermittent targeted therapies and stochastic evolution in patients affected by chronic myeloid leukemia

Front line therapy for the treatment of patients affected by chronic myeloid leukemia (CML) is based on the administration of tyrosine kinase inhibitors, namely imatinib or, more recently, axitinib. Although imatinib is highly effective and represents an example of a successful molecular targeted therapy, the appearance of resistance is observed in a proportion of patients, especially those in advanced stages. In this work, we investigate the appearance of resistance in patients affected by CML, by modeling the evolutionary dynamics of cancerous cell populations in a simulated patient treated by an intermittent targeted therapy. We simulate, with the Monte Carlo method, the stochastic evolution of initially healthy cells to leukemic clones, due to genetic mutations and changes in their reproductive behavior. We first present the model and its validation with experimental data by considering a continuous therapy. Then, we investigate how fluctuations in the number of leukemic cells affect patient response to the therapy when the drug is administered with an intermittent time scheduling. Here we show that an intermittent therapy (IT) represents a valid choice in patients with high risk of toxicity, despite an associated delay to the complete restoration of healthy cells. Moreover, a suitably tuned IT can reduce the probability of developing resistance

Doping dependence of spin dynamics of drifting electrons in GaAs bulks

We study the effect of the impurity density on lifetimes and relaxation lengths of electron spins in the presence of a static electric field in an n-type GaAs bulk. The transport of electrons and the spin dynamics are simulated by using a semiclassical Monte Carlo approach, which takes into account the intravalley scattering mechanisms of warm electrons in the semiconductor material. Spin relaxation is considered through the D’yakonov–Perel mechanism, which is the dominant mechanism in III–V semiconductors. The evolution of spin polarization is analyzed by computing lifetimes and depolarization lengths as a function of the doping density in the range 10^{13} - 5*10^{16} cm^{-3}, for different values of the amplitude of the static electric field (0.1 - 1.0 kV/cm). We find an increase of the electron spin lifetime as a function of the doping density, more evident for lattice temperatures lower than 150 K. Moreover, at very low intensities of the driving field, the spin depolarization length shows a nonmonotonic behaviour with the density. At the room temperature, spin lifetimes and depolarization lengths are nearly independent on the doping density. The underlying physics is analyzed