Estimation of Buttiker-Landauer traversal time based on the visibility of transmission current

We present a proposal for the estimation of B\"uttiker-Landauer traversal time based on the visibility of transmission current. We analyze the tunneling phenomena with a time-dependent potential and obtain the time-dependent transmission current. We found that the visibility is directly connected to the traversal time. Furthermore, this result is valid not only for rectangular potential barrier but also for general form of potential to which the WKB approximation is applicable . We compared these results with the numerical values obtained from the simulation of Nelson's quantum mechanics. Both of them fit together and it shows our method is very effective to measure experimentally the traversal time.Comment: 12 pages, REVTeX, including 7 eps figure

Interactional Research Into Problem-Based Learning

Problem-based learning (PBL) has been deployed as a student-centered instructional approach and curriculum design in a wide range of academic fields across the world. The majority of educational research to date has focused on knowledge-based outcomes addressing why PBL is useful. Researchers of PBL are developing a growing interest in qualitative research with a process-driven orientation to examining learning interactions. It is essential to broaden this research base so as to support PBL designs and approaches to leading students into higher-order thinking and a deeper approach to learning. Interactional Research Into Problem-Based Learning explores how students learn in an inquiry-led approach such as PBL. Included are studies that focus on learning in situ and go beyond measuring the outcomes of PBL. The goal is to further expand the PBL research base of qualitative investigations examining the social dimension and lived experience of teaching and learning within the PBL process. A second aim of this volume is to shed light on the methodological aspects of researching PBL, adding new perspectives to the current trends in qualitative studies on PBL. Chapters cover ethnographic approaches to video analysis, introspective protocols such as stimulated recall, and longitudinal qualitative studies using discourse-based analytic approaches. Specifically, this book will further contribute to the current educational research both theoretically and empirically in the following key areas: students’ learning processes in PBL over time and across contexts; the nature of quality interactions in PBL tutorials; the (inter)cultural aspects of learning in PBL; facilitation processes and group dynamics in synchronous and asynchronous face-to-face and blended PBL; and the developing nature of PBL learner identity.https://docs.lib.purdue.edu/purduepress_previews/1058/thumbnail.jp

An introduction to the EPR-Chameleon experiment

On September 27 (2001), as a side activity to the "Japan-Italy Joint workshop on: Quantum open systems and quantum measurement", the first; public demonstration of the dynamical EPR-chameleon experiment was performed at Waseda University in order to give an experimental answer to a long standing question in the foundations of quantum theory: do there exist classical macroscopic systems which, by local independent choices, produce sequences of data which reproduce the singlet correlations, hence violating Bell's inequality? The EPR-chameleon experiment gives an affirmative answer to this question by concretely producing an example of such systems in the form of three personal computers which realize a local deterministic dynamical evolution whose mathematical structure is very simple and transparent. In the experiment performed on September 27 the local dynamics used was not a reversible one because the interaction with the degrees of freedom of the apparatus was integrated out giving rise to an effective Markovian dynamics which, although mapping probability measures into probability measures, did not preserve the +/- 1-values of the spin (or polarization) observables. This feature was criticized by some of the partecipants and the following two questions arose: i) is it possible to prove that the Markovian evolution, used in the experiment, is indeed the reduced evolution of a bona fide reversible evolution? ii) if the answer to question (i) is affirmative, is it possible to reproduce the EPR correlations by simply considering empirical averages of +/- 1-values, as one does in usual EPR type experiments? An affirmative answer to these questions was given in the paper [AcImRe01] and it is briefly reviewed in what follows

Tunneling Time Distribution by means of Nelson's Quantum Mechanics and Wave-Particle Duality

We calculate a tunneling time distribution by means of Nelson's quantum mechanics and investigate its statistical properties. The relationship between the average and deviation of tunneling time suggests the exsistence of ``wave-particle duality'' in the tunneling phenomena.Comment: 14 pages including 11 figures, the text has been revise

Time of arrival through interacting environments: Tunneling processes

We discuss the propagation of wave packets through interacting environments. Such environments generally modify the dispersion relation or shape of the wave function. To study such effects in detail, we define the distribution function P_{X}(T), which describes the arrival time T of a packet at a detector located at point X. We calculate P_{X}(T) for wave packets traveling through a tunneling barrier and find that our results actually explain recent experiments. We compare our results with Nelson's stochastic interpretation of quantum mechanics and resolve a paradox previously apparent in Nelson's viewpoint about the tunneling time.Comment: Latex 19 pages, 11 eps figures, title modified, comments and references added, final versio

From the cell membrane to the nucleus: unearthing transport mechanisms for Dynein

Mutations in the motor protein cytoplasmic dynein have been found to cause Charcot-Marie-Tooth disease, spinal muscular atrophy, and severe intellectual disabilities in humans. In mouse models, neurodegeneration is observed. We sought to develop a novel model which could incorporate the effects of mutations on distance travelled and velocity. A mechanical model for the dynein mediated transport of endosomes is derived from first principles and solved numerically. The effects of variations in model parameter values are analysed to find those that have a significant impact on velocity and distance travelled. The model successfully describes the processivity of dynein and matches qualitatively the velocity profiles observed in experiments