Focus group study of older drivers

The report describes findings from a study exploring the driving practices and driving-related beliefs and attitudes of older persons. The methodology employed was a modified focus group technique. Participants, 162 currently licensed drivers aged 56-86 living in five different geographic locations in British Columbia met in 31small groups (mean size 5.2 persons) to discuss eight topics. These topics concerned their driving practices; attitudes and I beliefs about their own and other older persons\u27 driving behaviour; their driving difficulties; ways in which road or traffic signs and signals could be changed to make driving easier for them; their feelings about a series of questions relating to the retesting of older drivers, criteria for licence renewal and driving cessation; concerning driver education courses for older persons, traffic violations they most frequently commit and their experience of medication affecting their driving. Throughout the report data are presented separately for respondents aged 55-65, 66-75 and 76 and over. Where noticeable, differences between the three age groups are highlighted

Using the Behaviour Change Wheel to identify barriers and enablers to the delivery of webchat counselling for young people

Webchat counselling is increasingly utilised to deliver mental health services to young people. Despite potential barriers to its delivery, a systematic investigation has not yet been conducted. This qualitative study examined barriers and enablers to the delivery of webchat counselling through text communication and identified possible strategies to tackle these, on behalf of counsellors volunteering for an online charity offering psychological support to young people aged below 25. The current investigation was conducted using the Behaviour Change Wheel, a validated and systematic framework employed to guide intervention development and optimisation. Qualitative interviews were carried out with eight volunteers. Thematic analysis identified 11 core themes. Barriers were lack of online communication skills, lack of training to work online with young people, technical difficulties, reduced technical supervision during out-of-office hours, duration of webchat counselling sessions, perceived level of effectiveness, perceived establishment of a therapeutic relationship and perceived confidence in delivering webchat counselling. Enablers were familiarity with technology, flexibility and the absence of physical characteristics. These themes were perceived by counsellors as barriers or enablers depending on factors such as experience with technology and work shifts. Using the Behaviour Change Wheel (BCW), intervention functions and behaviour change techniques to address these barriers and optimise the service were identified, such as providing counsellors with training to work online with young people, learning new presence techniques to foster emotional connectedness between counsellors and clients, adding time to sessions to compensate for time taken to complete questionnaires and increasing technical support and supervision during out-of-office hours

Dynamics of waves in 1D electron systems: Density oscillations driven by population inversion

We explore dynamics of a density pulse induced by a local quench in a one-dimensional electron system. The spectral curvature leads to an "overturn" (population inversion) of the wave. We show that beyond this time the density profile develops strong oscillations with a period much larger than the Fermi wave length. The effect is studied first for the case of free fermions by means of direct quantum simulations and via semiclassical analysis of the evolution of Wigner function. We demonstrate then that the period of oscillations is correctly reproduced by a hydrodynamic theory with an appropriate dispersive term. Finally, we explore the effect of different types of electron-electron interaction on the phenomenon. We show that sufficiently strong interaction [$U(r)\gg 1/mr^2$ where $m$ is the fermionic mass and $r$ the relevant spatial scale] determines the dominant dispersive term in the hydrodynamic equations. Hydrodynamic theory reveals crucial dependence of the density evolution on the relative sign of the interaction and the density perturbation.Comment: 20 pages, 13 figure

Zero bias anomaly out of equilibrium

The non-equilibrium zero bias anomaly (ZBA) in the tunneling density of states of a diffusive metallic film is studied. An effective action describing virtual fluctuations out-of-equilibrium is derived. The singular behavior of the equilibrium ZBA is smoothed out by real processes of inelastic scattering.Comment: 4 page

Ballistic transport in disordered graphene

An analytic theory of electron transport in disordered graphene in a ballistic geometry is developed. We consider a sample of a large width W and analyze the evolution of the conductance, the shot noise, and the full statistics of the charge transfer with increasing length L, both at the Dirac point and at a finite gate voltage. The transfer matrix approach combined with the disorder perturbation theory and the renormalization group is used. We also discuss the crossover to the diffusive regime and construct a ``phase diagram'' of various transport regimes in graphene.Comment: 23 pages, 10 figure

Many-particle correlations in non-equilibrium Luttinger liquid

We develop an operator-based approach to the problem of Luttinger liquid conductor in a non-equilibrium stationary state. We show that the coherent-state many-body fermionic density matrix as well as all fermionic correlation functions out of equilibrium are given by one-dimensional functional determinants of the Fredholm type. Thus, the model constitutes a remarkable example of a many-body problem where all the correlation functions can be evaluated exactly. On the basis of the general formalism we investigate four-point correlation functions of the fermions coming out of the Luttinger liquid wire. Obtained correlations in the fermionic distribution functions represent the combined effect of interaction and non-equilibrium conditions.Comment: 23 pages,7 figure

Boson-assisted tunneling in layered metals

A theory for boson-assisted tunneling via randomly distributed resonant states in a layered metals is developed. As particular examples, we consider the electron-phonon interaction and the interaction between localized and conduction electrons. The theory is applied to explain a non-monotonic variation of the out-plane resistivity with temperature observed in quasi-two-dimensional metals.Comment: 14 pages, 5 figure

Non-equilibrium Luttinger liquid: Zero-bias anomaly and dephasing

A one-dimensional system of interacting electrons out of equilibrium is studied in the framework of the Luttinger liquid model. We analyze several setups and develop a theory of tunneling into such systems. A remarkable property of the problem is the absence of relaxation in energy distribution functions of left- and right-movers, yet the presence of the finite dephasing rate due to electron-electron scattering, which smears zero-bias-anomaly singularities in the tunneling density of states.Comment: 5 pages, 2 figure

Modulation theory of quantum tunneling into a Calogero-Sutherland fluid

Quantum hydrodynamics of interacting electrons with a parabolic single particle spectrum is studied using the Calogero-Sutherland model. The effective action and modulation equations, describing evolution of periodic excitations in the fluid, are derived. Applications to the problem of a single electron tunneling into the FQHE edge state are discussed

Full counting statistics of a chaotic cavity with asymmetric leads

We study the statistics of charge transport in a chaotic cavity attached to external reservoirs by two openings of different size which transmit non-equal number of quantum channels. An exact formula for the cumulant generating function has been derived by means of the Keldysh-Green function technique within the circuit theory of mesoscopic transport. The derived formula determines the full counting statistics of charge transport, i.e., the probability distribution and all-order cumulants of current noise. It is found that, for asymmetric cavities, in contrast to other mesoscopic systems, the third-order cumulant changes the sign at high biases. This effect is attributed to the skewness of the distribution of transmission eigenvalues with respect to forward/backward scattering. For a symmetric cavity we find that the third cumulant approaches a voltage-independent constant proportional to the temperature and the number of quantum channels in the leads.Comment: new section on probability distribution and new references adde