11,985 research outputs found
Photon-assisted Fano Resonance and Corresponding Shot-Noise in a Quantum Dot
We have studied the Fano resonance in photon-assisted transport in a quantum
dot and calculated both the coherent current and spectral density of shot
noise. It is predicted, for the first time, that the shape of Fano profile will
also appear in satellite peaks. It is found that the variations of Fano
profiles with the strengths of nonresonant transmissions are not synchronous in
absorption and emission sidebands. The effect of interference on
photon-assisted pumped current has been also investigated. We further predict
the current and spectral density of shot noise as a function of the phase,
which exhibits an intrinsic property of resonant and nonresonant channels in
the structures.Comment: 4 pages, 5 figure
Treatment of high cervical arteriovenous fistulas in the craniocervical junction region
The craniocervical junction (CCJ) is a complex region. Rarely, arteriovenous fistulas (AVFs) can occur in the CCJ region. Currently, it is accepted that CCJ AVFs should only refer to AVFs at the C1-C2 levels. It is reasonable to assume that high cervical CCJ AVFs are being referred to when discussing CCJ AVFs. High cervical CCJ AVFs can be divided into the following four types: dural AVF, radicular AVF, epidural AVF and perimedullary AVF. Until now, it was difficult to understand high cervical CCJ AVFs and provide a proper treatment for them. Therefore, an updated review of high cervical CCJ AVFs is necessary. In this review, the following issues are discussed: the definition of high cervical CCJ AVFs, vessel anatomy of the CCJ region, angioarchitecture of high cervical CCJ AVFs, treatment options, prognoses and complications. Based on the review and our experience, we found that the four types of high cervical CCJ AVFs share similar clinical and imaging characteristics. Patients may present with intracranial hemorrhage or congestive myelopathy. Treatment, including open surgery and endovascular treatment (EVT), can be used for symptomatic AVFs. Most high cervical CCJ AVFs can be effectively treated with open surgery. EVT remains challenging due to a high rate of incomplete obliteration and complications, and it can only be performed in superselective AVFs with simple angioarchitecture. Appropriate treatment can lead to a good prognosis
Nearly Massless Electrons in the Silicon Interface with a Metal Film
We demonstrate the realization of nearly massless electrons in the most
widely used device material, silicon, at the interface with a metal film. Using
angle-resolved photoemission, we found that the surface band of a monolayer
lead film drives a hole band of the Si inversion layer formed at the interface
with the film to have nearly linear dispersion with an effective mass about 20
times lighter than bulk Si and comparable to graphene. The reduction of mass
can be accounted for by repulsive interaction between neighboring bands of the
metal film and Si substrate. Our result suggests a promising way to take
advantage of massless carriers in silicon-based thin-film devices, which can
also be applied for various other semiconductor devices.Comment: 4 pages, 4 figures, accepted for publication in Physical Review
Letter
Federated Learning for Semantic Parsing: Task Formulation, Evaluation Setup, New Algorithms
This paper studies a new task of federated learning (FL) for semantic
parsing, where multiple clients collaboratively train one global model without
sharing their semantic parsing data. By leveraging data from multiple clients,
the FL paradigm can be especially beneficial for clients that have little
training data to develop a data-hungry neural semantic parser on their own. We
propose an evaluation setup to study this task, where we re-purpose widely-used
single-domain text-to-SQL datasets as clients to form a realistic heterogeneous
FL setting and collaboratively train a global model. As standard FL algorithms
suffer from the high client heterogeneity in our realistic setup, we further
propose a novel LOss Reduction Adjusted Re-weighting (Lorar) mechanism to
mitigate the performance degradation, which adjusts each client's contribution
to the global model update based on its training loss reduction during each
round. Our intuition is that the larger the loss reduction, the further away
the current global model is from the client's local optimum, and the larger
weight the client should get. By applying Lorar to three widely adopted FL
algorithms (FedAvg, FedOPT and FedProx), we observe that their performance can
be improved substantially on average (4%-20% absolute gain under MacroAvg) and
that clients with smaller datasets enjoy larger performance gains. In addition,
the global model converges faster for almost all the clients.Comment: ACL 2023 long pape
mixiTUI:A Tangible Sequencer for Electronic Live Performances
With the rise of crowdsourcing and mobile crowdsensing techniques, a large
number of crowdsourcing applications or platforms (CAP) have appeared. In the
mean time, CAP-related models and frameworks based on different research
hypotheses are rapidly emerging, and they usually address specific issues from
a certain perspective. Due to different settings and conditions, different
models are not compatible with each other. However, CAP urgently needs to
combine these techniques to form a unified framework. In addition, these models
needs to be learned and updated online with the extension of crowdsourced data
and task types, thus requiring a unified architecture that integrates lifelong
learning concepts and breaks down the barriers between different modules. This
paper draws on the idea of ubiquitous operating systems and proposes a novel OS
(CrowdOS), which is an abstract software layer running between native OS and
application layer. In particular, based on an in-depth analysis of the complex
crowd environment and diverse characteristics of heterogeneous tasks, we
construct the OS kernel and three core frameworks including Task Resolution and
Assignment Framework (TRAF), Integrated Resource Management (IRM), and Task
Result quality Optimization (TRO). In addition, we validate the usability of
CrowdOS, module correctness and development efficiency. Our evaluation further
reveals TRO brings enormous improvement in efficiency and a reduction in energy
consumption
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