610 research outputs found
Observability of surface Andreev bound states in a topological insulator in proximity to an s-wave superconductor
To guide experimental work on the search for Majorana zero-energy modes, we
calculate the superconducting pairing symmetry of a three-dimensional
topological insulator in combination with an s-wave superconductor. In analogy
to the case of nanowires with strong spin-orbit coupling we show how the
pairing symmetry changes across different topological regimes. We demonstrate
that a dominant p-wave pairing relation is not sufficient to realize a Majorana
zero-energy mode useful for quantum computation. Our main result of this paper
is the relation between odd-frequency pairing and Majorana zero energy modes by
using Green functions techniques in three-dimensional topological insulators in
the so-called Majorana regime. We discuss thereafter how the pairing relations
in the different regimes can be observed in the shape of the tunneling
conductance of an s-wave proximized three-dimensional topological insulator. We
will discuss the necessity to incorporate a ferromagnetic insulator to localize
the zero-energy bound state to the interface as a Majorana mode.Comment: Accepted for publication in Journal of Physics: Condensed Matte
Inbreeding versus Crossbreeding: the Potential Bias of Breeding Values in Dutch Dairy Cattle
Inbreeding and crossbreeding oppositely affect the performance of livestock; inbreeding negatively- and crossbreeding positively affects all traits. This study examined if it is appropriate that breeding value estimations (EBVs) in Dutch dairy cattle only take into account the effects of crossbreeding (heterosis). Performance and EBVs for milk yield, fat, and protein; somatic cell count; and fertility of 219 purebred Holstein Friesian cows and 191 crossbred cows were compared. The outcomes suggest a bias in the EBVs for milk yield, and fat; and fertility, that may very well be caused by inbreeding depression
Nonlocal Andreev reflection, fractional charge and current-phase relation in topological bilayer exciton condensate junctions
We study Andreev reflection and Josephson currents in topological bilayer
exciton condensates (TEC). These systems can create 100% spin entangled
nonlocal currents with high amplitudes due to perfect nonlocal Andreev
reflection. This Andreev reflection process can be gate tuned from a regime of
purely retro reflection to purely specular reflection. We have studied the
bound states in TEC-TI-TEC Josephson junctions and find a gapless dispersion
for perpendicular incidence. The presence of a sharp transition in the
supercurrent-phase relationship when the system is in equilibrium is a
signature of fractional charge, which can be further revealed in ac
measurements faster than relaxation processes via Landau-Zener processes.Comment: Submitted to Physical Review
Conduction spectroscopy of a proximity induced superconducting topological insulator
The combination of superconductivity and the helical spin-momentum locking at
the surface state of a topological insulator (TI) has been predicted to give
rise to p-wave superconductivity and Majorana bound states. The
superconductivity can be induced by the proximity effect of a an s-wave
superconductor (S) into the TI. To probe the superconducting correlations
inside the TI, dI/dV spectroscopy has been performed across such S-TI
interfaces. Both the alloyed BiSbTeSe and the
stoichiometric BiSbTeSe have been used as three dimensional TI. In the case
of BiSbTeSe, the presence of disorder induced
electron-electron interactions can give rise to an additional zero-bias
resistance peak. For the stoichiometric BiSbTeSe with less disorder, tunnel
barriers were employed in order to enhance the signal from the interface. The
general observations in the spectra of a large variety of samples are
conductance dips at the induced gap voltage, combined with an increased sub-gap
conductance, consistent with p-wave predictions. The induced gap voltage is
typically smaller than the gap of the Nb superconducting electrode, especially
in the presence of an intentional tunnel barrier. Additional uncovered
spectroscopic features are oscillations that are linearly spaced in energy, as
well as a possible second order parameter component.Comment: Semiconductor Science and Technology; Special Issue on Hybrid Quantum
Materials and Device
Vehicle Specific Behaviour in Macroscopic Traffic Modelling through Stochastic Advection Invariant
AbstractIn this contribution a new model to include stochastic vehicle specific behaviour and interaction in traffic flow modelling is presented. The First Order Model with Stochastic Advection (FOMSA) is presented as a first order macroscopic kinematic wave model in a platoon-based Lagrangian coordinate system. The use of Lagrangian coordinates allows characteristics of specific vehicles or vehicle-groups to propagate along with the traffic flow using a vehicle specific invariant. The invariant reflects how vehicle or platoon specific characteristics propagate with the vehicles and influence the local behaviour of a vehicle or platoon on a macroscopic level and in interaction with other surrounding vehicles. It represents a local vehicle specific adjustment to the critical density and makes use of two parameters: a stochastic boundary parameter and a transition parameter. These parameters indicate the extent of differences between vehicles or platoons. A case study is also presented in which a demonstration of the model is given and the face validity and sensitivity of the parameters are shown. Previously, similar approaches have made use of second order model descriptions. The formulation of this model as a first order model makes use of the advantages of first order models and also applies the improved accuracy of Lagrangian coordinates over the Eulerian coordinate system in time-stepping
Towards predictive cardiovascular safety : a systems pharmacology approach
Cardiovascular safety issues related to changes in blood pressure, arise frequently in drug development. In the thesis __Towards predictive cardiovascular safety __ a systems pharmacology approach__, a system-specific model is described to quantify drug effects on the interrelationship between mean arterial pressure, cardiac output, heart rate, stroke volume and total peripheral resistance in rats. The developed model can be used to quantify and predict the dynamic changes in the cardiovascular system (CVS) and elucidate the mechanism of action of novel compounds. An ultimate application of this system-specific CVS model would be to facilitate the anticipation of the clinical response based on preclinical data for newly developed compounds. Furthermore, the developed system-specific CVS model was combined with receptor models to quantify and predict the cardiovascular effects of the sphingosine 1-phosphate (S1P) receptor agonists, fingolimod-phosphate (fingolimod-P)and siponimod, in rats. This systems pharmacology model provided a quantitative understanding of the cardiovascular effects of fingolimod-P and siponimod and can be applied to predict the cardiovascular effects of other S1P receptor agonists with different selectivity profiles in rats. Ultimately, it may constitute a basis for prediction of cardiovascular effects of S1P receptor agonists in humansNovartis, LAP&P Consultants BVUBL - phd migration 201
A Multiclass Simulation-Based Dynamic Traffic Assignment Model for Mixed Traffic Flow of Connected and Autonomous Vehicles and Human-Driven Vehicles
One of the potential capabilities of Connected and Autonomous Vehicles (CAVs)
is that they can have different route choice behavior and driving behavior
compared to human Driven Vehicles (HDVs). This will lead to mixed traffic flow
with multiple classes of route choice behavior. Therefore, it is crucial to
solve the multiclass Traffic Assignment Problem (TAP) in mixed traffic of CAVs
and HDVs. Few studies have tried to solve this problem; however, most used
analytical solutions, which are challenging to implement in real and large
networks (especially in dynamic cases). Also, studies in implementing
simulation-based methods have not considered all of CAVs' potential
capabilities. On the other hand, several different (conflicting) assumptions
are made about the CAV's route choice behavior in these studies. So, providing
a tool that can solve the multiclass TAP of mixed traffic under different
assumptions can help researchers to understand the impacts of CAVs better. To
fill these gaps, this study provides an open-source solution framework of the
multiclass simulation-based traffic assignment problem for mixed traffic of
CAVs and HDVs. This model assumes that CAVs follow system optimal principles
with rerouting capability, while HDVs follow user equilibrium principles.
Moreover, this model can capture the impacts of CAVs on road capacity by
considering distinct driving behavioral models in both micro and meso scales
traffic simulation. This proposed model is tested in two case studies which
shows that as the penetration rate of CAVs increases, the total travel time of
all vehicles decreases
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