2,402 research outputs found
Near-wall velocity of suspended particles in microchannel flow
This contribution investigates the characteristic reduction of the particle velocity with respect to the velocity profile of a pure liquid (water) in a pressure driven flow (PDF). It is shown by simulations and experiments that particles are slowed down once their local perturbation "cloud" of the velocity field hits the wall. We show that this effect scales with the ratio of the distance of sphere's surface from the wall, a, and the radius, a, of the sphere, i.e. delta/a
Electron-Phonon Coupling in Boron-Doped Diamond Superconductor
The electronic structure, lattice dynamics, and electron-phonon coupling of
the boron-doped diamond are investigated using the density functional supercell
method. Our results indicate the boron-doped diamond is a phonon mediated
superconductor, con rming previous theoretical conclusions deduced from the
calculations employing the virtual crystal approximation. We show that the
optical phonon modes involving B vibrations play an important role in the
electron-phonon coupling. Di erent from previous theoretical results, our
calculated electron-phonon coupling constant is 0.39 and the estimated
superconducting transition temperature Tc is 4.4 K for the boron doped diamond
with 2.78% boron content using the Coulomb pseudopotential \mu*= 0.10, in
excellent agreement with the experimental result.Comment: 11 pages, 4 figures, Accepted by PR
Quantum Anomalous Hall Effect in Graphene Proximity Coupled to an Antiferromagnetic Insulator
We propose realizing the quantum anomalous Hall effect by proximity coupling
graphene to an antiferromagnetic insulator that provides both broken
time-reversal symmetry and spin-orbit coupling. We illustrate our idea by
performing ab initio calculations for graphene adsorbed on the (111) surface of
BiFeO3. In this case, we find that the proximity-induced exchange field in
graphene is about 70 meV, and that a topologically nontrivial band gap is
opened by Rashba spin-orbit coupling. The size of the gap depends on the
separation between the graphene and the thin film substrate, which can be tuned
experimentally by applying external pressure.Comment: 5pages, 5 figure
A Silicon Surface Code Architecture Resilient Against Leakage Errors
Spin qubits in silicon quantum dots are one of the most promising building
blocks for large scale quantum computers thanks to their high qubit density and
compatibility with the existing semiconductor technologies. High fidelity
single-qubit gates exceeding the threshold of error correction codes like the
surface code have been demonstrated, while two-qubit gates have reached 98\%
fidelity and are improving rapidly. However, there are other types of error ---
such as charge leakage and propagation --- that may occur in quantum dot arrays
and which cannot be corrected by quantum error correction codes, making them
potentially damaging even when their probability is small. We propose a surface
code architecture for silicon quantum dot spin qubits that is robust against
leakage errors by incorporating multi-electron mediator dots. Charge leakage in
the qubit dots is transferred to the mediator dots via charge relaxation
processes and then removed using charge reservoirs attached to the mediators. A
stabiliser-check cycle, optimised for our hardware, then removes the
correlations between the residual physical errors. Through simulations we
obtain the surface code threshold for the charge leakage errors and show that
in our architecture the damage due to charge leakage errors is reduced to a
similar level to that of the usual depolarising gate noise. Spin leakage errors
in our architecture are constrained to only ancilla qubits and can be removed
during quantum error correction via reinitialisations of ancillae, which ensure
the robustness of our architecture against spin leakage as well. Our use of an
elongated mediator dots creates spaces throughout the quantum dot array for
charge reservoirs, measuring devices and control gates, providing the
scalability in the design
Memento Mori: The development and validation of the Death Reflection Scale
Despite its potential for advancing organizational behavior (OB) research, the topic of death awareness has been vastly understudied. Moreover, research on death awareness has predominantly focused on the anxiety‐provoking aspect of death‐related cognitions, thus overlooking the positive aspect of death awareness, death reflection. This gap is exacerbated by the lack of a valid research instrument to measure death reflection. To address this issue, we offer a systematic conceptualization of death reflection, develop the Death Reflection Scale, and assess its psychometric properties across four studies. Further, using a sample of 268 firefighters, we examine whether death reflection buffers the detrimental impact of mortality cues at work on employee well‐being and safety performance. Results provide strong support for the psychometric properties of the Death Reflection Scale. Further, moderation analysis indicates death reflection weakens the negative effect of mortality cues on firefighters' safety performance. Overall, these findings suggest the newly developed Death Reflection Scale will prove useful in future research on death‐related cognitions
Cross-domain Adaptation with Discrepancy Minimization for Text-independent Forensic Speaker Verification
Forensic audio analysis for speaker verification offers unique challenges due
to location/scenario uncertainty and diversity mismatch between reference and
naturalistic field recordings. The lack of real naturalistic forensic audio
corpora with ground-truth speaker identity represents a major challenge in this
field. It is also difficult to directly employ small-scale domain-specific data
to train complex neural network architectures due to domain mismatch and loss
in performance. Alternatively, cross-domain speaker verification for multiple
acoustic environments is a challenging task which could advance research in
audio forensics. In this study, we introduce a CRSS-Forensics audio dataset
collected in multiple acoustic environments. We pre-train a CNN-based network
using the VoxCeleb data, followed by an approach which fine-tunes part of the
high-level network layers with clean speech from CRSS-Forensics. Based on this
fine-tuned model, we align domain-specific distributions in the embedding space
with the discrepancy loss and maximum mean discrepancy (MMD). This maintains
effective performance on the clean set, while simultaneously generalizes the
model to other acoustic domains. From the results, we demonstrate that diverse
acoustic environments affect the speaker verification performance, and that our
proposed approach of cross-domain adaptation can significantly improve the
results in this scenario.Comment: To appear in INTERSPEECH 202
The finite-width Laplace sum rules for scalar glueball in instanton liquid model
In the framework of a semi-classical expansion for quantum chromodynamics in
the instanton liquid background, the correlation function of the
scalar glueball current is given. Besides the pure classical and quantum
contributions, the contributions arising from the interactions between the
classical instanton fields and quantum gluons are taken into account as well.
Instead of the usual zero-width approximation for the resonance, the
Brite-Wigner form for the spectral function of the finite-width resonance is
adopted. The family of the Laplace sum rules for the scalar glueball in quantum
chromodynamics with and without light quarks are studed. A consistency between
the subtracted and unsubtracted sum rules are very well justified, and the
values of the mass, decay width, and the coupling to the corresponding current
for the resonance in which the glueball fraction is dominant, are
obtained.Comment: 6 figure
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