1,721,150 research outputs found
Magnetic confinement of massless Dirac fermions in graphene
No full textBecause of Klein tunneling, electrostatic potentials are unable to confine Dirac electrons. We show that it is possible to confine massless Dirac fermions in a monolayer graphene sheet by inhomogeneous magnetic fields. This allows one to design mesoscopic structures in graphene by magnetic barriers, e.g., quantum dots or quantum point contacts
Magnetic barriers and confinement of Dirac-Weyl quasiparticles in graphene
No full textWe discuss the properties of the two-dimensional massless Dirac-Weyl quasiparticles realized in graphene monolayers in the presence of inhomogeneous magnetic fields. We show that in contrast to electrostatic barriers, appropriate magnetic barriers are able to confine these quasiparticles. This allows for a novel way of designing mesoscopic structures (e.g., quantum dots, quantum point contacts) in graphene
Superconducting nonequilibrium transport through a weakly interacting quantum dot
No full textWe study the out-of-equilibrium current through an interacting quantum dot, which is modeled as an Anderson impurity contacted by two BCS superconductors held at fixed voltage bias. In order to account for multiple Andreev reflections, we develop a Keldysh Green’s function scheme perturbative in the dot’s interaction strength. We find an unexpected enhancement of the current due to repulsive interactions for small to intermediate lead-to-dot couplings
Dispersive drumhead states in nodal-line semimetal junctions
Full text linkWe consider a smooth interface between a topological nodal-line semimetal and a topologically trivial insulator (e.g., the vacuum) or another semimetal with a nodal ring of different radius. Using a low-energy effective Hamiltonian including only the two crossing bands, we show that these junctions accommodate a two-dimensional zero-energy level and a set of two-dimensional dispersive bands, corresponding to states localized at the interface. We characterize the spectrum, identifying the parameter ranges in which these states are present, and highlight the role of the nodal radius and the smoothness of the interface. We also suggest material-independent ways to detect and identify these states, using optical conductivity and infrared absorption spectroscopy in magnetic field
Topological Kondo Effect
No full textWe review recent theoretical progress in the understanding of the topological Kondo effect in Coulomb-blockaded Majorana devices and generalizations thereof. The central ingredient in Majorana devices is the so-called Majorana box which encodes a spin-1/2 degree of freedom in the Majorana subspace that can be addressed by electron cotunneling processes. In particular, after explaining the basic physics of the topological Kondo effect in a Majorana box connected to a set of normal-conducting leads, we discuss the Josephson current-phase relation in a superconducting multi-terminal setup where the central junction is again formed by a Majorana box but the leads are phase-biased superconductors. For large Kondo temperature, one finds that the competition between two-channel Kondo physics and the gap opening in the leads results in a 6π periodicity of the current-phase relation. This periodicity is due to the fractionalized charge excitations characterizing the non-Fermi liquid two-channel Kondo fixed point. We also explore generalizations of this Majorana-based topological Kondo setup to platforms hosting parafermionic excitations
Incoming Partners: Integrating operations
No full textLearning objectives:
- Demonstrate how an incoming agent can take advantage of the internet for distributing their products.
- Explore technological and business innovations essential for incoming agents.
- Illustrate the system architecture for an incoming agent.
- Explain the functions of technology for incoming agencies
The Province of Rimini: Communicating with the customer
No full textLearning objectives:
- Illustrate how ICTs play a key part in assisting DMOs in their operations, with important functions both in networking of local organizations and in promoting destination brand and products on the global market.
- Demonstrate how the Province of Rimini uses technologies and media for promotion and marketing.
- Illustrate the advantages of the destination management system for Rimini.
- Explain how a thorough analysis of target customers can ensure the development of a useful and usable reference system
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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