The amazing graphene: an educational bridge connecting different Physics concepts

The purpose of this work is to present a learning workshop covering various physics concepts aimed at strengthening physics/engineering student understanding about the remarkable properties of two dimensional materials, graphene in particular. At the basis of this learning experience is the idea of blending and interconnecting separate pieces of knowledge already acquired by undergraduates in different courses and to help them visualize and link the concepts lying beyond separate chunks of information or equations. Graphene represents an appropriate unifying framework to achieve this task in view of its monatomic structure and various exotic processes peculiar to this and some other two dimensional crystals. We first discuss essential elements of group theory and their application to the symmetry properties of graphene with the aim of presenting to physics/electronic engineering undergraduates that in a system characterized by symmetry properties such as a crystal, the acquisition of the solutions of the Schr\uf6dinger equation is simpler and easier to visualize than when these properties are ignored. We have then selected and discussed some remarkable properties of graphene: the linear electron energy-momentum dispersion relation in proximity of some edge points of the Brillouin zone; the consequential massless Dirac behaviour of the electrons; their tunnelling behaviour and the related Klein paradox; the chiral behaviour of electrons and holes; the fractional quantum Hall effect in massless particles; and the quantum behaviour of correlated quasiparticles observable at macroscopic level. These arguments are presented in a context covering related pieces of knowledge about classical, quantum and relativistic mechanics. Finally, we mention current applications and possible future ones with the aim of providing students with an expertise that could be useful for further work experiences and scientific investigations regarding new materials, having farreaching implications in various fields such as basic physics, materials science and engineering applications

Pedagogical Models Of Surface Mechanical Wave Propagation In Various Materials

We report on a teaching approach oriented to the understanding of some relevant concepts of wave propagation in solids. It is based on simple experiments involving the propagation of shock mechanical waves in solid slabs of various materials. Methods similar to the generation and propagation of seismic waves are adopted. Educational seismometers, interfaced with computers, are used to detect and visualize the shock waves and to analyse their propagation properties. A qualitative discussion of the results concerning the propagation and the attenuation of the waves allows us to draw basic conclusions about the response of the matter to solicitation impacts and their propagation

Active learning in a real-world bioengineering problem: A pilot-study on ophthalmologic data processing

Active learning is a format alternative to the conventional lecture/recitation/laboratory; research results have reported that it is suitable to encourage student inquiry and foster peer mentoring. Although the availability of computer-based learning materials in biomedical sciences is increasing, there are relatively few studies aimed to integrate traditional methods of teaching with inquiry-based approaches utilizing these Information and Communication Technologies (ICT) tools. This paper describes a pilot-study on a comprehensive active laboratory course about digital ophthalmologic signal classification, experienced by a group of undergraduates in Bio-Electronic Engineering. During the activity, the students became able to discriminate healthy subjects from patients affected by two retinal pathologies: Achromatopsia or Congenital Stationary Night Blindness. The study was based on the analysis and classification of the electroretinograms, that record the retinal response to a light flash. To process electroretinographic data, a software based on the Empirical Mode Decomposition and an Artificial Neural Network was used. Our findings indicate that this laboratory experience can be considered effective in improving student's reasoning skills and that students acting as investigators achieve a better outcome, presumably because this activity satisfies their psychological needs for autonomy, competence, and relatedness

A 5E-Based Learning Workshop on Various Aspects of the Hall Effect

Learning activities in constructivist environments are characterized by active engagement, inquiry, problem solving, and collaboration with peers. The 5E learning cycle is a student-centered instructional model for constructivism, where the students perform five phases of instruction: Engagement, Exploration, Explanation, Elaboration, Evaluation. The purpose of this contribution is to present a 5E-based learning path of advanced physics aimed at strengthening Physics/Engineering student understanding about the quantum Hall effect, a phenomenon observed at low temperatures in a two-dimensional electron gas subject to a strong perpendicular magnetic field. The quantum Hall effect, a rare example of microscopic effects observable on a macroscopic scale, allows us to establish very precise values of microscopic quantities, such as the electron charge and the Planck constant. In the present learning path, we stimulate a discussion about the integer and fractional quantum Hall effects, aimed at introducing a unified picture based upon composite fermions, interacting quasiparticles that may be viewed as fermions carrying attached a fictitious magnetic flux. Finally, we discuss the quantum effect in graphene, the ‘miracle material’ for its unique and exceptional properties

A Stochastic Approach to Quantum Statistics Distributions: Theoretical Derivation and Monte Carlo Modelling

Abstract. We present a method aimed at a stochastic derivation of the equilibrium distribution of a classical/quantum ideal gas in the framework of the canonical ensemble. The time evolution of these ideal systems is modelled as a series of transitions from one system microstate to another one and thermal equilibrium is reached via a random walk in the single-particle state space. We look at this dynamic process as a Markov chain satisfying the condition of detailed balance and propose a variant of the Monte Carlo Metropolis algorithm able to take into account indistinguishability of identical quantum particles. Simulations performed on different two-dimensional (2D) systems are revealed to be capable of reproducing the correct trends of the distribution functions and other thermodynamic properties. The simulations allow us to show that, away from the thermodynamic limit, a pseudo-Bose–Einstein condensation occurs for a 2D ideal gas of bosons

Analysis of the human a-wave ERG component

The a-wave is one of the main issues of research in the field of ocular electrophysiology, since it is strictly connected with early photoreceptoral activities. The present study proposes mathematical methods that analyse this component in human subjects, and supports experimental evidence relating to possible correlations among the responses of photoreceptoral units under a light stimulus. The investigation is organized in two parts: the first part concerns the onset and the initial slope, up to the first minimum (about 10-15 ms), the second part deals with the main portion of the wave, up to about 30 ms. In both cases, the a-waves, recorded at various levels of luminance, have been fitted with a set of appropriate functions representing possible models of physiological behaviour which would take place in the early stages of phototransduction. The statistical nature of the underlying processes is also discussed. The results indicate that correlations occur in the early stages, whereas random processes are set up later