The first year of the “open discovery of stem laboratories” (ODL) project

2018

The Open Discovery of STEM Laboratories (ODL) project, co-funded by the European Community Erasmus+ KA2 program for 30 months, starting from November 2015, involves five countries: Spain, Italy, Greece, Estonia and Lithuania. It aims to implement teacher collaboration in creating and using μMOOCs (very short version of MOOCs-Massive Open Online Courses) for encouraging the use of STEM (Science, Technology, Engineering and Mathematics) remote/virtual laboratories into lessons. The challenge of the project is to impact on teaching process and inspire pedagogical innovation and modernization by means of open education resources, teaching/learning tools and best practices provided by European e…

The BioS4You European project: An innovative way to effectively engage Z-generation students in STEM disciplines

2021

In this contribution, we present the BioS4You project and analyse the results obtained in the first 18 months of its activity. The “Bio-Inspired STEM topics for engaging young generations” (BioS4You) Erasmus+ KA2 Innovation project aims to bridge the gap between STEM national curricula (which include Science, Technology, Engineering, and Mathematics) and the needs of Z-generation students, uninterested to basic themes, but enthusiastic in issues related to environmental, social, and health concerns. The BioS4You project engages young learners in STEM subjects, starting with current issues of interest for them, as the social and environmental impact of new technologies, connecting STEM conce…

Long term stability of learning outcomes in undergraduates after an open-inquiry instruction on thermal science

2018

This paper investigates the efficacy of an open-inquiry approach to achieve a long term stability of physics instruction. This study represents the natural continuation of a research project started four years ago when a sample of thirty engineering undergraduates, having already attended traditional university physics instruction, were involved in a six-week long learning experience of open-inquiry research activities within the highly motivating context of developing a thermodynamically efficient space base on Mars. Four years later, we explore the effectiveness of that learning experience by analyzing the outcomes that the students achieved by answering again the same questionnaire that …

Elucidating the electron transport in semiconductors via Monte Carlo simulations: An inquiry-driven learning path for engineering undergraduates

2015

Within the context of higher education for science or engineering undergraduates, we present an inquiry-driven learning path aimed at developing a more meaningful conceptual understanding of the electron dynamics in semiconductors in the presence of applied electric fields. The electron transport in a nondegenerate n-type indium phosphide bulk semiconductor is modelled using a multivalley Monte Carlo approach. The main characteristics of the electron dynamics are explored under different values of the driving electric field, lattice temperature and impurity density. Simulation results are presented by following a question-driven path of exploration, starting from the validation of the model…

From led light signboards to the Planck’s constant

2018

Recent studies have highlighted an alarming decline in young people’s interest towards the study of scientific subjects, often considered interesting but not easily understood and appreciated by students. In particular, the introduction of Modern Physics (MP) key-topics at secondary school level is a difficult and complex task because MP involves abstract ideas and requires a strong mathematical background. In this communication we present and discuss the results of an inquiry-based teaching/learning path aimed at surmounting the difficulties of an exclusively theoretical approach to the introduction of MP topics. In particular, we planned and realized an inquiry-driven learning environment…

Open-inquiry driven overcoming of epistemological difficulties in engineering undergraduates: A case study in the context of thermal science

2014

This paper addresses the efficacy of an open-inquiry approach that allows students to build on traditionally received knowledge. A sample of thirty engineering undergraduates, having already attended traditional university physics instruction, was selected for this study. The students were involved in a six- week long learning experience of open-inquiry research activities within the highly motivating context of developing a thermodynamically efficient space base on Mars. They designed and carried out their own scientific investigations, which involved gathering information, collecting and analyzing data, providing explanations, and sharing results. A questionnaire containing fifteen open-e…

Empirical mode decomposition and neural network for the classification of electroretinographic data

2013

The processing of biosignals is increasingly being utilized in ambulatory situations in order to extract significant signals' features that can help in clinical diagnosis. However, this task is hampered by the fact that biomedical signals exhibit a complex behaviour characterized by strong non-linear and non-stationary properties that cannot always be perceived by simple visual examination. New processing methods need be considered. In this context, we propose to apply a signal processing method, based on empirical mode decomposition and artificial neural networks, to analyse electroretinograms, i.e. the retinal response to a light flash, with the aim to detect and classify retinal diseases…

Designing for Student-Centered Hybrid Learning Environments: A Framework for Programming Languages Course Design

2022

Hybrid learning environments are a means of delivering instructional content in that online educational materials and opportunities for interaction were combined with traditional classroom methods. Hybrid learning environments give students the opportunity to work in an environment enriched with digital learning tools, and to support student-based learning approach. Student-based learning approach promotes engagement to make students active learners via various ways such as interactivity, feedback, etc. Researchers identified feedback as an activity for promoting effective online learning and more so creating the environment for teacher-student teaching and learning interaction. Besides, so…

External Noise Effects in Doped Semiconductors Operating Under sub-THz Signals

2012

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.

Nonlinear relaxation phenomena in metastable condensed matter systems

2016

Nonlinear relaxation phenomena in three different systems of condensed matter are investigated. (i) First, the phase dynamics in Josephson junctions is analyzed. Specifically, a superconductor-graphene-superconductor (SGS) system exhibits quantum metastable states, and the average escape time from these metastable states in the presence of Gaussian and correlated fluctuations is calculated, accounting for variations in the the noise source intensity and the bias frequency. Moreover, the transient dynamics of a long-overlap Josephson junction (JJ) subject to thermal fluctuations and non-Gaussian noise sources is investigated. Noise induced phenomena are observed, such as the noise enhanced s…

Stochastic dynamics of leukemic cells under an intermittent targeted therapy

2009

The evolutionary dynamics of cancerous cell populations in a model of Chronic Myeloid Leukemia (CML) is investigated in the presence of an intermittent targeted therapy. Cancer development and progression is modeled by simulating the stochastic evolution of initially healthy cells which can experience genetic mutations and modify their reproductive behavior, becoming leukemic clones. Front line therapy for the treatment of patients affected by CML is based on the administration of tyrosine kinase inhibitors, namely imatinib (Gleevec) or, more recently, dasatinib or nilotinib. Despite the fact that they represent the first example of a successful molecular targeted therapy, the development o…

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

2019

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 exam…

The amazing graphene: an educational bridge connecting different Physics concepts

2017

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 dim…

Electronic properties of graphene: A learning path for undergraduate students

2016

The purpose of this work is to present a learning path aimed at deepening student understanding of the fundamental concepts underlying the electronic properties of new materials, graphene in particular. To achieve this task, we propose a five-week long workshop where students may be introduced to fundamental concepts of advanced physics, rarely used in learning paths, such as the symmetry properties of the crystal lattice, the group theory , the features of the free electron wave functions and energy levels, the relativistic Dirac equation. Particular emphasis is given to the manner of introducing these concepts, since an essential knowledge of solid state physics, quantum physics and relat…

Analysing the conceptions on modelling of engineering undergraduate students: A case study using cluster analysis

2016

The problem of taking a set of data and separating it into subgroups where the elements of each subgroup are more similar to each other than they are to elements not in the subgroup has been extensively studied through the statistical method of Cluster Analysis . This method can be conveniently used to separate students into groups that can be recognized and characterized by common traits in their answers, without any prior knowledge of what form those groups would take (unsupervised classification). In the last years many studies examined the consistency of students’ answers in a variety of situations. Some of these papers have tried to develop more detailed models of the consistency of st…

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

2019

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 …

A quantitative analysis of university student reasoning lines in the field of thermally activated phenomena

2018

In this contribution we present a research aimed at studying the effectiveness of two workshops in improving reasoning skills in undergraduate students. Both the workshops are based on the Feynman Unifying Approach. A questionnaire containing six open-ended questions on the temperature dependence of evaporation of a liquid and of a chemical reaction was administered to the students of both groups before instruction. A second one, similar to the first but focused on a physical content different from both the pre-instruction test one and the content dealt with during the workshops, was administered after instruction. The responses to the pre- and post-instruction questionnaires are analyzed b…

An inquiry-based learning path to introduce modern physics in high-school

2018

Although Modern Physics (MP) is a scientific field of increasingly interest, due to its mathematical and conceptual difficulty, it was not generally taught in Italian high-schools. Recently, in order to reduce the gap between school curricula and modern technology, the Ministry of Education promoted the inclusion of MP in Italian secondary schools. MP hot topics produce interest and enthusiasm in learners at all ages, but to address this topic in high school in an effective way it is necessary to translate complex theories and highly-advanced experiments into an understandable language appreciated by students. In this contribution, we discuss an inquiry-driven learning sequence suitable to …

Monte Carlo Simulation of Electron Dynamics in Doped Semiconductors Driven by Electric Fields: Harmonic Generation, Hot-Carrier Noise and Spin Relaxa…

2011

In solid state electronics the miniaturization of integrated circuits implies that, even at moderate applied voltages, the components can be exposed to very intense electric fields. Advances in electronics push the devices to operate also under cyclostationary conditions, i.e. under large-signal and time-periodic conditions. A main consequence of this fact is that circuits exhibit a strongly nonlinear behavior. Furthermore, semiconductor based devices are always imbedded into a noisy environment that could strongly affect their performance, setting the lower limit for signal detection in electronic circuits. For this reason, to fully understand the complex scenario of the nonlinear phenomen…

Inquiry-based environments for bio-signal processing training in engineering education

2021

Active student engagement, teaching via experience in real-life settings and learning by doing, are pedagogical strategies appropriate to improve student-reasoning skills. By building models, performing investigations, examining and explaining experimental results, using theoretical and computational thinking, constructing representations, undergraduates can acquire a deeper understanding of fundamental disciplinary concepts while reinforcing transversal abilities. In this framework, Engineering courses should be designed with the final objective to develop practical skills, focusing on hands-on activities. This contribution presents two different inquiry-based learning environments recent…

Evaluating the Effectiveness of Modelling-Oriented Workshops for Engineering Undergraduates in the Field of Thermally Activated Phenomena

2017

Two 20-h modelling-based workshops focused on the explanation of ther- mally activated phenomena were held at the University of Palermo, Italy, during the Academic Year 2014–2015. One of them was conducted by applying an inquiry-based approach, while the other, still based on laboratory and modelling activities, was not focused on inquiry. Seventy-two students belonging to the Undergraduate Program for Chemical Engineering attended the two workshops. The related content was focused on an à la Feynman unifying approach to thermally activated phenomena. Question- naires were administered to the students of both groups, before and post instruction. Responses were analysed using k-means cluster…

New insights into electron spin dynamics in the presence of correlated noise

2011

The changes of the spin depolarization length in zinc-blende semiconductors when an external component of correlated noise is added to a static driving electric field are analyzed for different values of field strength, noise amplitude and correlation time. Electron dynamics is simulated by a Monte Carlo procedure which keeps into account all the possible scattering phenomena of the hot electrons in the medium and includes the evolution of spin polarization. Spin depolarization is studied by examinating the decay of the initial spin polarization of the conduction electrons through the D'yakonov-Perel process, the only relevant relaxation mechanism in III-V crystals. Our results show that, f…

Monte Carlo analysis of polymer translocation with deterministic and noisy electric fields

2012

AbstractPolymer translocation through the nanochannel is studied by means of a Monte Carlo approach, in the presence of a static or oscillating external electric voltage. The polymer is described as a chain molecule according to the two-dimensional “bond fluctuation model”. It moves through a piecewise linear channel, which mimics a nanopore in a biological membrane. The monomers of the chain interact with the walls of the channel, modelled as a reflecting barrier. We analyze the polymer dynamics, concentrating on the translocation time through the channel, when an external electric field is applied. By introducing a source of coloured noise, we analyze the effect of correlated random fluct…

Training pre-service and in-service secondary school teachers: Analysis of changes in perceptions about quantum physics concepts and NoS views

2016

In this work we focus on the study of the changes in perceptions about Quantum Physics concepts and Nature of Science (NoS) Views of secondary school teachers attending three different typologies of professional development courses on Modern Physics . An open-ended questionnaire has been properly developed and administered in order to investigate Quantum Mechanics conceptual issues, NoS views and motivational aspects for all involved teachers. The same questionnaire has been submitted to the teachers both prior-to and after the courses. The analysis of teachers’ pre-instruction answers highlights that the majority of them show several difficulties on both conceptual knowledge and epistemolo…

HOT-ELECTRON NOISE FEATURES IN SILICON CRYSTALS OPERATING UNDER PERIODIC SIGNALS

2014

We study the intrinsic noise in n-type Si crystals operating under high-frequency periodic electric fields. To simulate the dy- namics of electrons in the bulk, by taking into account the main details of band structure, scattering processes, as well as heating effects, a Monte Carlo approach is used. The noise properties are investigated by computing the velocity fluctuations correlation function, its spectral density, and the total noise power for different values of the amplitude and frequency of the driving field. We show that the noise features are significantly affected by the electric field amplitude and frequency and discuss their peculiari- ties in comparison with those exhibited in…

Application of remote experiments in a secondary school using MOOC approach

2017

This paper presents first attempt to incorporate remote and virtual experiments in MOOC environment for the secondary school instruction. In case study the VISIR+ remote experiment of the WebLab-Deusto was used. The basic topic of physics “Resistors in series” was suggested for the mentioned above experiment. The open edX platform was employed to build the MOOC for the school lesson — we named it ‘micro-MOOC’. The results could be helpful for secondary school sector representatives, education instructors, parents and policy makers to respond to current and future education needs.

The BioS4YOU project: how Science Education can enhance student capacity to be participatory citizens in a transforming world

Recent studies evidence the need to engage students at all levels in Science to boost the supply of a skilled scientific workforce and knowledgeable citizenry. The “Bio-Inspired STEM topics for engaging young generations” (BioS4YOU) project, funded by the European Union within the Erasmus+ KA2 Innovation program, aims to bridge the gap between the STEM national curricula (which mostly include basic contents of Science, Technology, Engineering, and Mathematics) and the needs of Z-generation students, apathetic/uninterested to basic themes, but enthusiastic in issues related to environmental, social, and health concerns. The main goal of the BioS4You project is to engage European young learne…

An innovative tailored instructional design for computer programming courses in engineering

2023

Industry 4.0 and 5.0 topics are emerging fields and have seen rising demand recently. There is a critical need, on the other hand, for improved methods of instructing programming languages since a growing lack of student motivation during the pandemic has had a deleterious influence on the education of programmers. In this context, online/hybrid computer programming courses must be addressed with innovative solutions to support the field with well-educated professionals. In this paper, we present a case study to propose an innovative tailored instructional design for the online/hybrid learning environments for programming courses in engineering faculties. To develop the instructional design…

Evolutionary dynamics of imatinib-treated leukemic cells by stochastic approach

2008

The evolutionary dynamics of a system of cancerous cells in a model of chronic myeloid leukemia (CML) is investigated by a statistical approach. Cancer progression is explored by applying a Monte Carlo method to simulate the stochastic behavior of cell reproduction and death in a population of blood cells which can experience genetic mutations. In CML front line therapy is represented by the tyrosine kinase inhibitor imatinib which strongly affects the reproduction of leukemic cells only. In this work, we analyze the effects of a targeted therapy on the evolutionary dynamics of normal, first-mutant and cancerous cell populations. Several scenarios of the evolutionary dynamics of imatinib-tr…

Translocation dynamics of a short polymer driven by an oscillating force

2013

Under the terms of the Creative Commons Attribution 3.0 Unported License.

A statistical description of the human a-wave ERG component

2008

An Inquiry-based approach to the Franck-Hertz experiment

2014

In this study we present the results of an inquiry-driven learning path experienced by a sample of 15 selected 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. Despite the instructor’s introduction to specific technological/engineering-based contents during the course, the students’ answers to an open-ended questionnaire, administered at the end of the lectures, demonstrated that the acquired knowledge was characterized by a strictly theoretical vision of quantum science, basically in terms of an artifi…

Stochastic modelling of imatinib-treated leukemic cells dynamics

2007

Open Inquiry based learning experiences to understand the Nature of Science

2014

In this paper we address the question of the efficacy of an inquiry-based learning approach, with different levels of teacher’s guidance, to introduce the students to fundamental aspects of the Nature of Science (NoS). Explicit pedagogical approaches, in which specific instruction on the topic of NoS is provided in addition to the engagement in scientific inquiry, are generally considered more effective with respect to implicit methods, where NoS conceptions are expected to develop as a natural consequence of inquiry-based learning experiences alone. In our study, we further explore the connections between scientific inquiry and implicit development of NoS conceptions, by investigating the …

ELECTRON SPIN RELAXATION PROCESS IN SILICON CRYSTALS

2014

Recently, electrical injection of spin polarization in n-type and p-type silicon has been experimentally carried out up to room-temperature. Despite of these preliminary but promising experimental results, a comprehensive theoretical framework concerning the influence of transport conditions on the phonon-induced spin depolarization process in silicon structures, in a wide range of values of temperature, doping concentration and amplitude of external fields, is still in a developing stage. In order to elucidate the electron transport and spin dynamics of conduction electrons in lightly doped n-type Si crystals we have performed semiclassical multiparticle Monte Carlo simulations and numeric…

Cancer growth dynamics: stochastic models and noise induced effects

2009

In the framework of the Michaelis-Menten (MM) reaction kinetics, we analyze the cancer growth dynamics in the presence of the immune response. We found the coexistence of noise enhanced stability (NES) and resonant activation (RA) phenomena which act in an opposite way with respect to the extinction of the tumor The role of the stochastic resonance (SR) in the case of weak cancer therapy has been analyzed. The evolutionary dynamics of a system of cancerous cells in a model of chronic myeloid leukemia (CML) is investigated by a Monte Carlo approach. We analyzed the effects of a targeted therapy on the evolutionary dynamics of normal, first-mutant and cancerous cell populations. We show how t…

Monte Carlo Calculation of Voltage-Current Nonlinearity and High-Order Harmonic Generation in GaAs Microstructures

2006

Stochastic model for an ecosystem of cancerous cells in Chronic Myeloid Leukemia

2008

Monte Carlo study of diffusion noise reduction in GaAs operating under periodic conditions

2009

The effects of an external correlated source of noise on the intrinsic carrier noise in a low-doped GaAs bulk, operating under periodic conditions, are investigated. Numerical residts confirm that the dynamical response of electrons driven by a high-frequency periodic electric field receives a benefit by the constructive interplay between the fluctuating field and the intrinsic noise of the system. In particidar, in this contribute we show a nonmonotonic behavior of the integrated spectral density, which value critically depends on the correlation time of the external noise source.

Monte Carlo Simulation of Spin Relaxation of Conduction Electrons in Silicon

2014

Recently, electrical injection of spin polarization in n-type and p-type silicon up to room-temperature has been experimental- ly carried out. Despite of these promising experimental results, a comprehensive theoretical framework concerning the influence of transport conditions on the spin depolarization process in silicon structures, in a wide range of values of temperature, doping concentration and amplitude of external fields, is still in a developing stage. In this contribution we use a semiclassical multiparti- cle Monte Carlo approach to simulate the electron transport and spin dynamics in lightly doped n-type Si crystals and numerically calculate the spin lifetimes of drifting electr…

External noise effects on the electron velocity fluctuations in semiconductors

2007

Time-frequency analysis of the human photoreceptoral response

2009

Electronic Noise in Semiconductor Systems: a Monte Carlo Simulation under Mixed Fields

2006

An approach based on wavelet analysis for feature extraction in the electroretinogram

2011

Most biomedical signals are non-stationary. The knowledge of their frequency content and temporal distribution is then useful in a clinical context. The wavelet analysis is appropriate to achieve this task. The present paper uses this method to reveal hidden characteristics and anomalies of the human a-wave, an important component of the electroretinogram since it is a measure of the functional integrity of the photoreceptors. We here analyse the time–frequency features of the a-wave both in normal subjects and in patients affected by Achromatopsia, a pathology disturbing the functionality of the cones. The results indicate the presence of two or three stable frequencies that, in the pathol…

Monte Carlo Analysis of Voltage-Current Characterstic Nonlinearity and Harmonic Generation in Submicron Semiconductor Structures

2006

Even and Odd Harmonic Generation in low-doped semiconductors

2004

Enhancement of the Lifetime of Metastable States in Er-Doped Si Nanocrystals by External Colored Noise

2015

The changes in the lifetime of a metastable energy level in Er-doped Si nanocrystals in the presence of an external source of colored noise are analyzed for different values of noise intensity and correlation time. Exciton dynamics is simulated by a set of phenomenological rate equations which take into account all the possible phenomena inherent in the energy states of Si nanocrystals and Er^{3+} ions in the host material of Si oxide. Electronic deexcitation is studied by examining the decay of the initial population of the Er atoms in the first excitation level 4I_{13/2} through fluorescence and cooperative energy transfer upconversion. Our results show that the deexcitation process of th…

Noise Enhanced Stability Phenomenon in Electron Spin Dynamics

2012

Possible utilization of the electron spin as an information carrier in electronic devices is an engaging challenge for future spin-based electronics. In these new devices, the information stored in a system of polarized electron spins, is transferred by applying an external electric field and finally detected. However, each initial non-equilibrium magnetization decays both in time and distance during the transport. Because of increasing miniaturization, to avoid too much intense electric fields, which could lead the system to exhibit a strongly nonlinear physical behavior, applied voltages are very low. Low voltages are subjected to the background noise; hence, it is mandatory to understand…

An Inquiry-based approach to the Franck-Hertz experiment

2015

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…

Epistemological Difficulties and Improvement of Conceptual Understanding in the Context of Thermal Sciences: An Open Inquiry Approach with Undergradu…

2016

We provide evidence that these OI experiences contribute positively to improve physics conceptual understanding and increase student abilities in problem solving, by providing the activation of appropriate epistemological resources.

Open Inquiry Investigations on Heat Transfer Performed by Undergraduate Engineering Students

2012

Many researches have shown the pedagogical effectiveness of structured inquiry as a high performance tool in science education of undergraduate engineering students. In this paper we report the preliminary results of an extended investigation on the efficacy of the application of an open inquiry approach to the consolidation of the physics concepts regarding the topic of thermal energy transfer. We selected a sample of undergraduate mechanical engineering students, who passed the examination of the basic physics courses with good marks. Firstly, we investigated about resistant misconceptions in thermal physics by administrating a pre-activity questionnaire. Even the best marked students sho…

Static-ElectricField Effects on harmonic generation in Gallium Arsenide Bulk exposed to intense sub-THz radiation

2006

Field mixing influence on the hot-electron noise in Semiconductors

2007

Using cluster analysis to study the modelling abilities of engineering undergraduate students: a case study

2016

In this contribution we discuss the application of a quantitative, non-hierarchical clustering method to make sense of the answers that 120 engineering undergraduates students at the University of Palermo, Italy, gave to four open-ended questions on the meaning of the modeling processes in Science. We will show that the use of non-hierarchical analysis allows us to easily separate students into groups that can be recognized and characterized by common traits in students’ answers without any prior knowledge on the part of the researcher of what form those groups would take (unbiased classification).

Monte Carlo Analysis of the efficiency of Tera-Hertz Harmonic Generation in semiconductors

2005

EFFECT OF A FLUCTUATING ELECTRIC FIELD ON ELECTRON SPIN DEPHASING TIME IN III–V SEMICONDUCTORS

2012

We investigate the electron spin dephasing in low n-doped GaAs semiconductor bulks driven by a correlated fluctuating electric field. The electron dynamics is simulated by a Monte Carlo procedure which keeps into account all the possible scattering phenomena of the hot electrons in the medium and includes the evolution of spin polarization. Spin relaxation times are computed through the D’yakonov–Perel process, which is the only relevant relaxation mechanism in zinc-blende semiconductors. The decay of initial spin polarization of conduction electrons is calculated for different values of field strength, noise intensity and noise correlation time. For values of noise correlation time compara…

Doping dependence of spin lifetime of drifting electrons in GaAs bulks

2010

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 a 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 the lifetimes and depolarization lengths as a function of the doping density in the range 10^{13} - 10^{16} cm^{-3}, for differ…

Noise features in InP semiconductors operating under static or sub-Terahertz electric fields

2014

The sensitivity of semiconductor based circuits is strongly affected by the presence of intrinsic noise, which limits the performance of electronic devices. For this reason, several studies have investigated and characterized the transport properties of hot-electrons in semiconductor structures, by analyzing the electronic noise in systems operating under static and/or large-signal periodic driving conditions. Previous studies on electron velocity fluctuations in III-V and covalent semiconductor crystals, driven by periodic electric fields, have shown that the total noise power depends on both the amplitude and the frequency of the excitation signals. On the other hand, to the best of our k…

Monte Carlo investigation of electron spin relaxation in GaAs crystals during low-field transport

2011

A great emerging interest within the condensed matter physics is the use of electron spin in semiconductor-based spintronic devices to perform both logic operations, communication and storage. In order to make spintronics a feasible technology, sufficiently long spin lifetimes and the possibility to manipulate, control and detect the spin polarization are required. The loss of spin polarization before, during and after the necessary operations is a crucial problem into spin device design; thus, a full understanding of the role played by the lattice temperature, the doping density and the amplitude of the applied electric field on the electron spin dynamics in semiconductors is essential for…

Metastability and Relaxation in Quantum and Mesoscopic Systems

2013

The transient dynamics and the relaxation of three quantum and mesoscopic systems are investigated. In particular we analyze: (i) a long Josephson junction (LJJ) driven by a non-Gaussian Lévy noise current; (ii) a metastable quantum dissipative system driven by an external periodical driving; and (iii) the electron spin relaxation process in n-type GaAs crystals driven by a fluctuating electric field. Specifically, in the first system the LJJ phase evolution is described by the perturbed sine-Gordon equation. We find the noise enhanced stability and resonant activation phenomena, by investigating the mean escape time as a function of the bias current frequency, noise intensity and length of…

Stochastic modelling of imatinib-treated leukemic cell dynamics

2007

Chronic Myeloid Leukemia (CML) is a slowly progressing cancer that makes the body produce too many cancerous myeloid white blood cells. The molecular characteristics of CML is the presence of a Philadelphia (Ph) chromosome, created by a reciprocal translocation of chromosomes 9 and 22 which generates the fusion oncogene BCR-ABL. The introduction of the ABL tyrosine kinase inhibitor imatinib (Gleevec) for the treatment of CML represents the first example of a successful targeted therapy. Despite its striking efficacy, however, the developement of resistance to imatinib is observed in a proportion of patients, expecially those with advanced-stage CML. In the present work, the dynamics of the …

Nonlinear dependence on temperature and field of electron spin depolarization in GaAs semiconductors

2009

In this work the influence of temperature and drift conditions on the electron spin relaxation in lightly doped n-type GaAs bulk semiconductors is investigated. The electron transport, including the evolution of the spin polarization vector, is simulated by a Monte Carlo procedure which keeps into account all the possible scattering phenomena of the hot electrons in the medium. Electron-spin states in semiconductor structures relax by scattering with imperfections, other carriers and phonons. Spin relaxation lengths and times are computed through the D'yakonov-Perel process since this is the more relevant spin relaxation mechanism in the regime of interest (10 < T < 300 K). The decay of the…

Effect of a fluctuating electric field on electron spin dephasing in III-V semiconductors

2011

In the present work we investigate electron spin relaxation in low-doped n-type GaAs semiconductor bulks driven by a static electric field. The electron dynamics is simulated by a Monte Carlo procedure which keeps into account all the possible scattering phenomena of the hot electrons in the medium and includes the evolution of spin polarization. Spin relaxation lengths are computed through the D’yakonov-Perel process, which is the only relevant relaxation mechanism in zinc-blende semiconductors. Since semiconductor based devices are always imbedded into a noisy environment that can strongly affect their performance, the decay of initial spin polarization of conduction electrons is calculat…

Complex dynamics of leukemic cells under intermittent therapy

2009

The evolutionary dynamics of cancerous cell populations in a model of Chronic Myeloid Leukemia (CML) is investigated. A Monte Carlo approach is applied to model the cancer development and progression by simulating the stochastic evolution of initially healthy cells which can experience genetic mutations and modify their reproductive behavior, becoming leukemic clones. Front line therapy for the treatment of this kind of tumor is achieved by tyrosine kinase inhibitors, namely imatinib (Gleevec) or, more recently, dasatinib or nilotinib. Despite they represent the first example of a successful molecular targeted therapy, the development of resistance to these drugs is observed in a proportion…

RELAXATION OF ELECTRON SPIN DURING FIELD TRANSPORT IN GaAs BULKS

2011

The spin depolarization of drifting electrons in a n-type doped GaAs bulk semiconductor is studied, in a wide range of lattice temperature (40 K < TL < 300 K) and doping density (10^{13} cm^{−3} < n < 10^{16} cm^{−3}), by adopting a semiclassical Monte Carlo approach. The effect of the mechanism of Dyakonov-Perel (DP) on the spin depolarization of the conduction electrons is analyzed as a function of the amplitude of a static electric field, ranging between 0.1 and 6 kV cm^{−1}, by considering the spin dynamics of electrons in both the Γ-valley and the upper L-valleys of the semiconductor. Moreover, the role of the electron-electron scattering mechanism in the suppression of DP spin relaxat…

Phonon-induced spin depolarization of conduction electrons in silicon crystals

2014

In last decade the process of spin relaxation of conduction electrons in semiconductor structures has been widely investigated, in order to use spin polarization as information carrier [1]. However, each initial non-equilibrium orientation decays over time during the transport. Thus, to make feasible the implementation of spin-based electronic devices, the features of spin relaxation at relatively high temperatures, jointly with the influence of transport conditions, should be fully understood [1]. Electrical injection of spin polarization in silicon structures up to room temperature has been experimentally carried out [2]. Despite these promising experimental results, a comprehensive theor…