192 research outputs found
Small data global regularity for simplified 3-D Ericksen-Leslie's compressible hyperbolic liquid crystal model
In this article, we consider the Ericksen-Leslie's hyperbolic system for
compressible liquid crystal model in three spatial dimensions. Global
regularity for small and smooth initial data near equilibrium is proved for the
case that the system is a nonlinear coupling of compressible Navier-Stokes
equations with wave map to . Our argument is a combination of
vector field method and Fourier analysis. The main strategy to prove global
regularity relies on an interplay between the control of high order energies
and decay estimates, which is based on the idea inspired by the method of
space-time resonances. In particular the different behaviors of the decay
properties of the density and velocity field for compressible fluids at
different frequencies play a key role.Comment: 61 pages; all comments wellcom
Scaling Limits of the Wasserstein information matrix on Gaussian Mixture Models
We consider the Wasserstein metric on the Gaussian mixture models (GMMs),
which is defined as the pullback of the full Wasserstein metric on the space of
smooth probability distributions with finite second moment. It derives a class
of Wasserstein metrics on probability simplices over one-dimensional bounded
homogeneous lattices via a scaling limit of the Wasserstein metric on GMMs.
Specifically, for a sequence of GMMs whose variances tend to zero, we prove
that the limit of the Wasserstein metric exists after certain renormalization.
Generalizations of this metric in general GMMs are established, including
inhomogeneous lattice models whose lattice gaps are not the same, extended GMMs
whose mean parameters of Gaussian components can also change, and the
second-order metric containing high-order information of the scaling limit. We
further study the Wasserstein gradient flows on GMMs for three typical
functionals: potential, internal, and interaction energies. Numerical examples
demonstrate the effectiveness of the proposed GMM models for approximating
Wasserstein gradient flows.Comment: 32 pages, 3 figure
Cosmological Fisher forecasts for next-generation spectroscopic surveys
Next-generation spectroscopic surveys such as the MegaMapper, MUltiplexed
Survey Telescope (MUST), MaunaKea Spectroscopic Explorer (MSE), and Wide
Spectroscopic Telescope (WST) are foreseen to increase the number of
galaxy/quasar redshifts by an order of magnitude, with hundred millions of
spectra that will be measured at . We perform a Fisher matrix analysis for
these surveys on the baryonic acoustic oscillation (BAO), the redshift-space
distortion (RSD) measurement, the non-Gaussianity amplitude , and
the total neutrino mass . For BAO and RSD parameters, these surveys may
achieve precision at sub-percent level (<0.5 per cent), representing an
improvement of factor 10 w.r.t. the latest database. For NG, these surveys may
reach an accuracy of . They can also put a tight
constraint on with if we do joint
analysis with Planck and even if combined with other data. In
addition, we introduce a general survey model, to derive the cosmic volume and
number density of tracers, given instrumental facilities and survey strategy.
Using our Fisher formalism, we can explore (continuously) a wide range of
survey observational parameters, and propose different survey strategies that
optimise the cosmological constraints. Fixing the fibre number and survey
duration, we show that the best strategy for and
measurement is to observe large volumes, despite the noise increase. However,
the strategy differs for the apparent magnitude limit. Finally, we prove that
increasing the fibre number improves measurement but not
significantly .Comment: 15 pages, 9 figure
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SelfâHealable and Recyclable Tactile Force Sensors with PostâTunable Sensitivity
It is challenging to postâtune the sensitivity of a tactile force sensor. Herein, a facile method is reported to tailor the sensing properties of conductive polymer composites by utilizing the liquidâlike property of dynamic polymer matrix at low strain rates. The idea is demonstrated using dynamic polymer composites (CB/dPDMS) made via evaporationâinduced gelation of the suspending toluene solution of carbon black (CB) and acidâcatalyzed dynamic polydimethylsiloxane (dPDMS). The dPDMS matrices allow CB to redistribute to change the sensitivity of materials at the liquidâlike state, but exhibit typical solidâlike behavior and thus can be used as strain sensors at normal strain rates. It is shown that the gauge factor of the polymer composites can be easily postâtuned from 1.4 to 51.5. In addition, the dynamic polymer matrices also endow the composites with interesting selfâhealing ability and recyclability. Therefore, it is envisioned that this method can be useful in the design of various novel tactile sensing materials for many applications
Federated Learning Incentive Mechanism under Buyers' Auction Market
Auction-based Federated Learning (AFL) enables open collaboration among
self-interested data consumers and data owners. Existing AFL approaches are
commonly under the assumption of sellers' market in that the service clients as
sellers are treated as scarce resources so that the aggregation servers as
buyers need to compete the bids. Yet, as the technology progresses, an
increasing number of qualified clients are now capable of performing federated
learning tasks, leading to shift from sellers' market to a buyers' market. In
this paper, we shift the angle by adapting the procurement auction framework,
aiming to explain the pricing behavior under buyers' market. Our modeling
starts with basic setting under complete information, then move further to the
scenario where sellers' information are not fully observable. In order to
select clients with high reliability and data quality, and to prevent from
external attacks, we utilize a blockchain-based reputation mechanism. The
experimental results validate the effectiveness of our approach
Portfolio-Based Incentive Mechanism Design for Cross-Device Federated Learning
In recent years, there has been a significant increase in attention towards
designing incentive mechanisms for federated learning (FL). Tremendous existing
studies attempt to design the solutions using various approaches (e.g., game
theory, reinforcement learning) under different settings. Yet the design of
incentive mechanism could be significantly biased in that clients' performance
in many applications is stochastic and hard to estimate. Properly handling this
stochasticity motivates this research, as it is not well addressed in
pioneering literature. In this paper, we focus on cross-device FL and propose a
multi-level FL architecture under the real scenarios. Considering the two
properties of clients' situations: uncertainty, correlation, we propose FL
Incentive Mechanism based on Portfolio theory (FL-IMP). As far as we are aware,
this is the pioneering application of portfolio theory to incentive mechanism
design aimed at resolving FL resource allocation problem. In order to more
accurately reflect practical FL scenarios, we introduce the Federated Learning
Agent-Based Model (FL-ABM) as a means of simulating autonomous clients. FL-ABM
enables us to gain a deeper understanding of the factors that influence the
system's outcomes. Experimental evaluations of our approach have extensively
validated its effectiveness and superior performance in comparison to the
benchmark methods
A matter of time: Using dynamics and theory to uncover mechanisms of transcriptional bursting
Eukaryotic transcription generally occurs in bursts of activity lasting
minutes to hours; however, state-of-the-art measurements have revealed that
many of the molecular processes that underlie bursting, such as transcription
factor binding to DNA, unfold on timescales of seconds. This temporal
disconnect lies at the heart of a broader challenge in physical biology of
predicting transcriptional outcomes and cellular decision-making from the
dynamics of underlying molecular processes. Here, we review how new dynamical
information about the processes underlying transcriptional control can be
combined with theoretical models that predict not only averaged transcriptional
dynamics, but also their variability, to formulate testable hypotheses about
the molecular mechanisms underlying transcriptional bursting and control.Comment: 41 pages, 4 figures, review articl
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