730 research outputs found
Topological features of hydrogenated graphene
Hydrogen adatoms are one of the most the promising proposals for the
functionalization of graphene. Hydrogen induces narrow resonances near the
Dirac energy, which lead to the formation of magnetic moments. Furthermore,
they also create local lattice distortions which enhance the spin-orbit
coupling. The combination of magnetism and spin-orbit coupling allows for a
rich variety of phases, some of which have non trivial topological features. We
analyze the interplay between magnetism and spin-orbit coupling in ordered
arrays of hydrogen on graphene monolayers, and classify the different phases
that may arise. We extend our model to consider arrays of adsorbates in
graphene-like crystals with stronger intrinsic spin-orbit couplings.Comment: 6 pages, 4 figure
The explanatory power of trust and commitment and stakeholders' salience : their influence on the reverse logistics programs performance
There is a growing awareness among practitioners and scholars regarding the importance of Relationship Marketing and its advantages in the supply chain management context. This is particularly appropriate for Reverse Logistics (RL) activities, which are characterized by several relationships between different stakeholders and the firm. Drawing on multiple theoretical approaches, we propose that RL programs result from the combination of external, organizational, and individual factors. We emphasize the role of trust and commitment as key influential elements on the RL systems implementation and their subsequent performance
THE EXPLANATORY POWER OF TRUST AND COMMITMENT AND STAKEHOLDERSâ SALIENCE: THEIR INFLUENCE ON THE REVERSE LOGISTICS PROGRAMS PERFORMANCE
There is a growing awareness among practitioners and scholars regarding the importance of Relationship Marketing and its advantages in the supply chain management context. This is particularly appropriate for Reverse Logistics (RL) activities, which are characterized by several relationships between different stakeholders and the firm. Drawing on multiple theoretical approaches, we propose that RL programs result from the combination of external, organizational, and individual factors. We emphasize the role of trust and commitment as key influential elements on the RL systems implementation and their subsequent performance.
Majorana Zero Modes in Graphene
A clear demonstration of topological superconductivity (TS) and Majorana zero
modes remains one of the major pending goal in the field of topological
materials. One common strategy to generate TS is through the coupling of an
s-wave superconductor to a helical half-metallic system. Numerous proposals for
the latter have been put forward in the literature, most of them based on
semiconductors or topological insulators with strong spin-orbit coupling. Here
we demonstrate an alternative approach for the creation of TS in
graphene/superconductor junctions without the need of spin-orbit coupling. Our
prediction stems from the helicity of graphene's zero Landau level edge states
in the presence of interactions, and on the possibility, experimentally
demonstrated, to tune their magnetic properties with in-plane magnetic fields.
We show how canted antiferromagnetic ordering in the graphene bulk close to
neutrality induces TS along the junction, and gives rise to isolated,
topologically protected Majorana bound states at either end. We also discuss
possible strategies to detect their presence in graphene Josephson junctions
through Fraunhofer pattern anomalies and Andreev spectroscopy. The latter in
particular exhibits strong unambiguous signatures of the presence of the
Majorana states in the form of universal zero bias anomalies. Remarkable
progress has recently been reported in the fabrication of the proposed type of
junctions, which offers a promising outlook for Majorana physics in graphene
systems.Comment: 14 pages, 8 figures. Included simulations of Andreev spectroscopy and
mor
Controlled complete suppression of single-atom inelastic spin and orbital cotunnelling
The inelastic portion of the tunnel current through an individual magnetic
atom grants unique access to read out and change the atom's spin state, but it
also provides a path for spontaneous relaxation and decoherence. Controlled
closure of the inelastic channel would allow for the latter to be switched off
at will, paving the way to coherent spin manipulation in single atoms. Here we
demonstrate complete closure of the inelastic channels for both spin and
orbital transitions due to a controlled geometric modification of the atom's
environment, using scanning tunnelling microscopy (STM). The observed
suppression of the excitation signal, which occurs for Co atoms assembled into
chain on a CuN substrate, indicates a structural transition affecting the
d orbital, effectively cutting off the STM tip from the spin-flip
cotunnelling path.Comment: 4 figures plus 4 supplementary figure
Self-assembly mechanism in colloids: perspectives from Statistical Physics
Motivated by recent experimental findings in chemical synthesis of colloidal
particles, we draw an analogy between self-assembly processes occurring in
biological systems (e.g. protein folding) and a new exciting possibility in the
field of material science. We consider a self-assembly process whose elementary
building blocks are decorated patchy colloids of various types, that
spontaneously drive the system toward a unique and predetermined targeted
macroscopic structure.
To this aim, we discuss a simple theoretical model -- the Kern-Frenkel model
-- describing a fluid of colloidal spherical particles with a pre-defined
number and distribution of solvophobic and solvophilic regions on their
surface. The solvophobic and solvophilic regions are described via a
short-range square-well and a hard-sphere potentials, respectively.
Integral equation and perturbation theories are presented to discuss
structural and thermodynamical properties, with particular emphasis on the
computation of the fluid-fluid (or gas-liquid) transition in the
temperature-density plane.
The model allows the description of both one and two attractive caps, as a
function of the fraction of covered attractive surface, thus interpolating
between a square-well and a hard-sphere fluid, upon changing the coverage.
By comparison with Monte Carlo simulations, we assess the pros and the cons
of both integral equation and perturbation theories in the present context of
patchy colloids, where the computational effort for numerical simulations is
rather demanding.Comment: 14 pages, 7 figures, Special issue for the SigmaPhi2011 conferenc
Semantic traffic sensor data: The TRAFAIR experience
Modern cities face pressing problems with transportation systems including, but not limited to, traffic congestion, safety, health, and pollution. To tackle them, public administrations have implemented roadside infrastructures such as cameras and sensors to collect data about environmental and traffic conditions. In the case of traffic sensor data not only the real-time data are essential, but also historical values need to be preserved and published. When real-time and historical data of smart cities become available, everyone can join an evidence-based debate on the city''s future evolution. The TRAFAIR (Understanding Traffic Flows to Improve Air Quality) project seeks to understand how traffic affects urban air quality. The project develops a platform to provide real-time and predicted values on air quality in several cities in Europe, encompassing tasks such as the deployment of low-cost air quality sensors, data collection and integration, modeling and prediction, the publication of open data, and the development of applications for end-users and public administrations. This paper explicitly focuses on the modeling and semantic annotation of traffic data. We present the tools and techniques used in the project and validate our strategies for data modeling and its semantic enrichment over two cities: Modena (Italy) and Zaragoza (Spain). An experimental evaluation shows that our approach to publish Linked Data is effective
Emergence of quasiparticle Bloch states in artificial crystals crafted atom-by-atom
The interaction of electrons with a periodic potential of atoms in
crystalline solids gives rise to band structure. The band structure of existing
materials can be measured by photoemission spectroscopy and accurately
understood in terms of the tight-binding model, however not many experimental
approaches exist that allow to tailor artificial crystal lattices using a
bottom-up approach. The ability to engineer and study atomically crafted
designer materials by scanning tunnelling microscopy and spectroscopy (STM/STS)
helps to understand the emergence of material properties. Here, we use atom
manipulation of individual vacancies in a chlorine monolayer on Cu(100) to
construct one- and two-dimensional structures of various densities and sizes.
Local STS measurements reveal the emergence of quasiparticle bands, evidenced
by standing Bloch waves, with tuneable dispersion. The experimental data are
understood in terms of a tight-binding model combined with an additional
broadening term that allows an estimation of the coupling to the underlying
substrate.Comment: 7 figures, 12 pages, main text and supplementary materia
Optimized random phase approximations for arbitrary reference systems: extremum conditions and thermodynamic consistence
The optimized random phase approximation (ORPA) for classical liquids is
re-examined in the framework of the generating functional approach to the
integral equations. We show that the two main variants of the approximation
correspond to the addition of the same correction to two different first order
approximations of the homogeneous liquid free energy. Furthermore, we show that
it is possible to consistently use the ORPA with arbitrary reference systems
described by continuous potentials and that the same approximation is
equivalent to a particular extremum condition for the corresponding generating
functional. Finally, it is possible to enforce the thermodynamic consistence
between the thermal and the virial route to the equation of state by requiring
the global extremum condition on the generating functional.Comment: 8 pages, RevTe
Analisis Struktur Dan Nilai-nilai Moral Yang Terkandung Dalam Cerpen Ten Made Todoke Karya Yoshida Genjiro
The sequence of this thesis are: first the writer collects the references and analyzes the data. Then, she obtained the data from Anthology of Japanese children's literature's book. The problems that will be studied in this thesis are intrinsicelements and the moral values contained in Ten Made Todoke Yoshida Genjiro's short story. This study uses structural method. The method is used to analyze the intrinsicelements that lead to moral values of the story. It makes the writer easier to analyze the moral values of story. The intrinsic elements that will be discussed in this thesis are theme, character, plot, setting, point of view, and the message of story
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