748 research outputs found
High Confidence Level Inference is Almost Free using Parallel Stochastic Optimization
Uncertainty quantification for estimation through stochastic optimization
solutions in an online setting has gained popularity recently. This paper
introduces a novel inference method focused on constructing confidence
intervals with efficient computation and fast convergence to the nominal level.
Specifically, we propose to use a small number of independent multi-runs to
acquire distribution information and construct a t-based confidence interval.
Our method requires minimal additional computation and memory beyond the
standard updating of estimates, making the inference process almost cost-free.
We provide a rigorous theoretical guarantee for the confidence interval,
demonstrating that the coverage is approximately exact with an explicit
convergence rate and allowing for high confidence level inference. In
particular, a new Gaussian approximation result is developed for the online
estimators to characterize the coverage properties of our confidence intervals
in terms of relative errors. Additionally, our method also allows for
leveraging parallel computing to further accelerate calculations using multiple
cores. It is easy to implement and can be integrated with existing stochastic
algorithms without the need for complicated modifications
What drives housing consumption in China? Based on a dynamic optimal general equilibrium model and spatial panel data analysis
Abstract. This paper examines the housing sales in China from 2004 to 2015 utilizing an optimal dynamic general equilibrium theoretical framework combined with a macroeconomic model. The spatial panel econometric empirical results suggest that housing prices and economic growth have increased housing sales in China. However, since house is considered as a special commodity in China, and unemployment show negative impacts on housing sales.Keywords. Energy use, Housing values, Optimal dynamic general equilibrium, Spatial panel econometrics, China.JEL. Q41, R31, E10
Programmed Design of a Lithium–Sulfur Battery Cathode by Integrating Functional Units
Sulfur is considered to be one of the most promising cathode materials due to its high theoretical specific capacity and low cost. However, the insulating nature of sulfur and notorious “shuttle effect” of lithium polysulfides (LiPSs) lead to severe loss of active sulfur, poor redox kinetics, and rapid capacity fade. Herein, a hierarchical electrode design is proposed to address these issues synchronously, which integrates multiple building blocks with specialized functions into an ensemble to construct a self‐supported versatile cathode for lithium–sulfur batteries. Nickel foam acts as a robust conductive scaffold. The heteroatom‐doped host carbon with desired lithiophilicity and electronic conductivity serving as a reservoir for loading sulfur can trap LiPSs and promote electron transfer to interfacial adsorbed LiPSs and Ni3S2 sites. The sulfurized carbon nanofiber forest can facilitate the Li‐ion and electron transport and retard the LiPSs diffusion as a barrier layer. Sulfiphilic Ni3S2 acts as both a chemical anchor with strong adsorption affinity to LiPSs and an efficient electrocatalyst for accelerating kinetics for redox conversion reactions. Synergistically, all functional units promote the lithium ion coupled electron transfer for binding and redox conversion of LiPSs, resulting in high reversible capacities, remarkable cycle stability, and excellent rate capability
Scalable manifold learning by uniform landmark sampling and constrained locally linear embedding
As a pivotal approach in machine learning and data science, manifold learning
aims to uncover the intrinsic low-dimensional structure within complex
nonlinear manifolds in high-dimensional space. By exploiting the manifold
hypothesis, various techniques for nonlinear dimension reduction have been
developed to facilitate visualization, classification, clustering, and gaining
key insights. Although existing manifold learning methods have achieved
remarkable successes, they still suffer from extensive distortions incurred in
the global structure, which hinders the understanding of underlying patterns.
Scalability issues also limit their applicability for handling large-scale
data. Here, we propose a scalable manifold learning (scML) method that can
manipulate large-scale and high-dimensional data in an efficient manner. It
starts by seeking a set of landmarks to construct the low-dimensional skeleton
of the entire data, and then incorporates the non-landmarks into the learned
space based on the constrained locally linear embedding (CLLE). We empirically
validated the effectiveness of scML on synthetic datasets and real-world
benchmarks of different types, and applied it to analyze the single-cell
transcriptomics and detect anomalies in electrocardiogram (ECG) signals. scML
scales well with increasing data sizes and embedding dimensions, and exhibits
promising performance in preserving the global structure. The experiments
demonstrate notable robustness in embedding quality as the sample rate
decreases.Comment: 33 pages, 10 figure
Distributed and Asynchronous Data Collection in Cognitive Radio Networks with Fairness Consideration
As a promising communication paradigm, Cognitive Radio Networks (CRNs) have paved a road for Secondary Users (SUs) to opportunistically exploit unused licensed spectrum without causing unacceptable interference to Primary Users (PUs). In this paper, we study the distributed data collection problem for asynchronous CRNs, which has not been addressed before. We study the Proper Carrier-sensing Range (PCR) for SUs. By working with this PCR, an SU can successfully conduct data transmission without disturbing the activities of PUs and other SUs. Subsequently, based on the PCR, we propose an Asynchronous Distributed Data Collection (ADDC) algorithm with fairness consideration for CRNs. ADDC collects a snapshot of data to the base station in a distributed manner without the time synchronization requirement. The algorithm is scalable and more practical compared with centralized and synchronized algorithms. Through comprehensive theoretical analysis, we show that ADDC is order-optimal in terms of delay and capacity, as long as an SU has a positive probability to access the spectrum. Furthermore, we extend ADDC to deal with the continuous data collection issue, and analyze the delay and capacity performances of ADDC for continuous data collection, which are also proven to be order-optimal. Finally, extensive simulation results indicate that ADDC can effectively accomplish a data collection task and significantly reduce data collection delay. [ABSTRACT FROM PUBLISHER
Epithelial-Mesenchymal Transition in tumor microenvironment
The epithelial to mesenchymal transition (EMT) plays crucial roles in the formation of the body plan and also in the tumor invasion process. In addition, EMT also causes disruption of cell-cell adherence, loss of apico-basal polarity, matrix remodeling, increased motility and invasiveness in promoting tumor metastasis. The tumor microenvironment plays an important role in facilitating cancer metastasis and may induce the occurrence of EMT in tumor cells. A large number of inflammatory cells infiltrating the tumor site, as well as hypoxia existing in a large area of tumor, in addition many stem cells present in tumor microenvironment, such as cancer stem cells (CSCs), mesenchymal stem cells (MSCs), all of these may be the inducers of EMT in tumor cells. The signaling pathways involved in EMT are various, including TGF-β, NF-κB, Wnt, Notch, and others. In this review, we discuss the current knowledge about the role of the tumor microenvironment in EMT and the related signaling pathways as well as the interaction between them
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