546 research outputs found
Anisotropic hybrid excitation modes in monolayer and double-layer phosphorene on polar substrates
We investigate the anisotropic hybrid plasmon-SO phonon dispersion relations
in monolayer and double-layer phosphorene systems located on the polar
substrates, such as SiO2, h-BN and Al2O3. We calculate these hybrid modes with
using the dynamical dielectric function in the RPA by considering the
electron-electron interaction and long-range electric field generated by the
substrate SO phonons via Frohlich interaction. In the long-wavelength limit, we
obtain some analytical expressions for the hybrid plasmon-SO phonon dispersion
relations which represent the behavior of these modes akin to the modes
obtaining from the loss function. Our results indicate a strong anisotropy in
plasmon-SO phonon modes, whereas they are stronger along the light-mass
direction in our heterostructures. Furthermore, we find that the type of
substrate has a significant effect on the dispersion relations of the coupled
modes. Also, by tuning the misalignment and separation between layers in
double-layer phosphorene on polar substrates, we can engineer the hybrid modes.Comment: 10 pages, 7 figure
Designing Precoding and Receive Matrices for Interference Alignment in MIMO Interference Channels
Interference is a key bottleneck in wireless communication
systems. Interference alignment is a management
technique that align interference from other transmitters in
the least possibly dimension subspace at each receiver and
provides the remaining dimensions for free interference signal.
An uncoordinated interference is an example of interference
which cannot be aligned coordinately with interference from
coordinated part; consequently, the performance of interference
alignment approaches are degraded. In this paper, we propose a
rank minimization method to enhance the performance of interference
alignment in the presence of uncoordinated interference
sources. Firstly, to obtain higher multiplexing gain, a new rank
minimization based optimization problem is proposed; then, a
new class of convex relaxation is introduced which can reduce
the optimal value of the problem and obtain lower rank solutions
by expanding the feasibility set. Simulation results show that our
proposed method can obtain considerably higher multiplexing
gain and sum rate than other approaches in the interference
alignment framework
Budgeted Online Model Selection and Fine-Tuning via Federated Learning
Online model selection involves selecting a model from a set of candidate
models 'on the fly' to perform prediction on a stream of data. The choice of
candidate models henceforth has a crucial impact on the performance. Although
employing a larger set of candidate models naturally leads to more flexibility
in model selection, this may be infeasible in cases where prediction tasks are
performed on edge devices with limited memory. Faced with this challenge, the
present paper proposes an online federated model selection framework where a
group of learners (clients) interacts with a server with sufficient memory such
that the server stores all candidate models. However, each client only chooses
to store a subset of models that can be fit into its memory and performs its
own prediction task using one of the stored models. Furthermore, employing the
proposed algorithm, clients and the server collaborate to fine-tune models to
adapt them to a non-stationary environment. Theoretical analysis proves that
the proposed algorithm enjoys sub-linear regret with respect to the best model
in hindsight. Experiments on real datasets demonstrate the effectiveness of the
proposed algorithm.Comment: Accepted by Transactions on Machine Learning Research (TMLR
Commentary: The History of Neurosurgery at Albany Medical College and Albany Medical Center Hospital, Albany, New York.
The origins of the Department of Neurosurgery at Albany Medical College closely parallel the development of early America and the establishment of modern health care.The tales of Washington Irving, the works of the Hudson River School of painters, and summers in the Catskill Mountains or Adirondacks are the stories that color the history of Upstate New York (Figure1). As a social, industrial, and political hub of the American colonies, New England’s need for centers providing structured medicine led to the creation of Albany Medical College in1839, one of the earliest such institutions in the young nation.1 Rapid progress in nearly every other realm of life required medical advancements as well, prompting subspecialization and the development of neurosurgery in the region
How Human Resource and Information Systems Practices Amplify the Returns on Information Technology Investments
This study examines the important roles that human resources (HR) for information technology (IT) professionals and information systems (IS) practices for all workers in an organization play in shaping returns on firms’ IT investments. In particular, we consider how incentives, autonomy, and training for IT professionals can enable a firm to better leverage the value of its IT investments. We argue that well-trained, motivated, and empowered IT professionals can help firms make better strategic choices in allocating IT investments and implementing IT projects. We also demonstrate how this moderating relationship depends upon collaborative IS and autonomy-enhancing IS practices that affect other knowledge workers in the firm. We leverage archival data for 228 firms with 736 firm-year observations and document two key findings. We find (1) that empowering HR practices for IT professionals positively moderate the effect of IT investments on firm performance, and (2) that the alignment between empowering HR practices for IT professionals and firm-wide collaborative IS practices enhances the value that firms derive from IT investments. Our results suggest that the business value of IT investments is linked to the rewards and opportunities offered to IT professionals, who have a pivotal role in the effective deployment of IT in organizations
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