2,958 research outputs found
Fermions Tunneling from Higher-Dimensional Reissner-Nordstr\"om Black Hole: Semiclassical and Beyond Semiclassical Approximation
Based on semiclassical tunneling method, we focus on charged fermions
tunneling from higher-dimensional Reissner-Nordstr\"{o}m black hole. We first
simplify the Dirac equation by semiclassical approximation, and then a
semiclassical Hamilton-Jacobi equation is obtained. Using the Hamilton-Jacobi
equation, we study the Hawking temperature and fermions tunneling rate at the
event horizon of the higher-dimensional Reissner-Nordstr\"{o}m black hole
spacetime. Finally, the correct entropy is calculation by the method beyond
semiclassical approximation.Comment: 7 page
Financial Crimes in Web3-empowered Metaverse: Taxonomy, Countermeasures, and Opportunities
At present, the concept of metaverse has sparked widespread attention from
the public to major industries. With the rapid development of blockchain and
Web3 technologies, the decentralized metaverse ecology has attracted a large
influx of users and capital.
Due to the lack of industry standards and regulatory rules, the
Web3-empowered metaverse ecosystem has witnessed a variety of financial crimes,
such as scams, code exploit, wash trading, money laundering, and illegal
services and shops. To this end, it is especially urgent and critical to
summarize and classify the financial security threats on the Web3-empowered
metaverse in order to maintain the long-term healthy development of its
ecology.
In this paper, we first outline the background, foundation, and applications
of the Web3 metaverse. Then, we provide a comprehensive overview and taxonomy
of the security risks and financial crimes that have emerged since the
development of the decentralized metaverse. For each financial crime, we focus
on three issues: a) existing definitions, b) relevant cases and analysis, and
c) existing academic research on this type of crime. Next, from the perspective
of academic research and government policy, we summarize the current anti-crime
measurements and technologies in the metaverse. Finally, we discuss the
opportunities and challenges in behavioral mining and the potential regulation
of financial activities in the metaverse.
The overview of this paper is expected to help readers better understand the
potential security threats in this emerging ecology, and to provide insights
and references for financial crime fighting.Comment: 24pages, 6 figures, 140 references, submitted to the Open Journal of
the Computer Societ
Meta-analysis for Discovering Rare-Variant Associations: Statistical Methods and Software Programs
There is heightened interest in using next-generation sequencing technologies to identify rare variants that influence complex human diseases and traits. Meta-analysis is essential to this endeavor because large sample sizes are required for detecting associations with rare variants. In this article, we provide a comprehensive overview of statistical methods for meta-analysis of sequencing studies for discovering rare-variant associations. Specifically, we discuss the calculation of relevant summary statistics from participating studies, the construction of gene-level association tests, the choice of transformation for quantitative traits, the use of fixed-effects versus random-effects models, and the removal of shadow association signals through conditional analysis. We also show that meta-analysis based on properly calculated summary statistics is as powerful as joint analysis of individual-participant data. In addition, we demonstrate the performance of different meta-analysis methods by using both simulated and empirical data. We then compare four major software packages for meta-analysis of rare-variant associations—MASS, RAREMETAL, MetaSKAT, and seqMeta—in terms of the underlying statistical methodology, analysis pipeline, and software interface. Finally, we present PreMeta, a software interface that integrates the four meta-analysis packages and allows a consortium to combine otherwise incompatible summary statistics
Meta-Analysis of Sequencing Studies With Heterogeneous Genetic Associations
Recent advances in sequencing technologies have made it possible to explore the influence of rare variants on complex diseases and traits. Meta-analysis is essential to this exploration because large sample sizes are required to detect rare variants. Several methods are available to conduct meta-analysis for rare variants under fixed-effects models, which assume that the genetic effects are the same across all studies. In practice, genetic associations are likely to be heterogeneous among studies because of differences in population composition, environmental factors, phenotype and genotype measurements, or analysis method. We propose random-effects models which allow the genetic effects to vary among studies and develop the corresponding meta-analysis methods for gene-level association tests. Our methods take score statistics, rather than individual participant data, as input and thus can accommodate any study designs and any phenotypes. We produce the random-effects versions of all commonly used gene-level association tests, including burden, variable threshold, and variance-component tests. We demonstrate through extensive simulation studies that our random-effects tests are substantially more powerful than the fixed-effects tests in the presence of moderate and high between-study heterogeneity and achieve similar power to the latter when the heterogeneity is low. The usefulness of the proposed methods is further illustrated with data from National Heart, Lung, and Blood Institute Exome Sequencing Project (NHLBI ESP). The relevant software is freely available
MASS: meta-analysis of score statistics for sequencing studies
Summary: MASS is a command-line program to perform meta-analysis of sequencing studies by combining the score statistics from multiple studies. It implements three types of multivariate tests that encompass all commonly used association tests for rare variants. The input files can be generated from the accompanying software SCORE-Seq. This bundle of programs allows analysis of large sequencing studies in a time and memory efficient manner.Availability and implementation: MASS and SCORE-Seq, including documentations and executables, are available at http://dlin.web.unc.edu/software/.Contact: [email protected]
Barrier Inhomogeneity of Schottky Diode on Nonpolar AlN Grown by Physical Vapor Transport
An aluminum nitride (AlN) Schottky barrier diode (SBD) was fabricated on a
nonpolar AlN crystal grown on tungsten substrate by physical vapor transport.
The Ni/Au-AlN SBD features a low ideality factor n of 3.3 and an effective
Schottky barrier height (SBH) of 1.05 eV at room temperature. The ideality
factor n decreases and the effective SBH increases at high temperatures. The
temperature dependences of n and SBH were explained using an inhomogeneous
model. A mean SBH of 2.105 eV was obtained for the Ni-AlN Schottky junction
from the inhomogeneity analysis of the current-voltage characteristics. An
equation in which the parameters have explicit physical meanings in thermionic
emission theory is proposed to describe the current-voltage characteristics of
inhomogeneous SBDs.Comment: 6 pages, 6 figure
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