451 research outputs found
Unconditional convergence and optimal error estimates of a Galerkin-mixed FEM for incompressible miscible flow in porous media
In this paper, we study the unconditional convergence and error estimates of
a Galerkin-mixed FEM with the linearized semi-implicit Euler time-discrete
scheme for the equations of incompressible miscible flow in porous media. We
prove that the optimal error estimates hold without any time-step
(convergence) condition, while all previous works require certain time-step
condition. Our theoretical results provide a new understanding on commonly-used
linearized schemes for nonlinear parabolic equations. The proof is based on a
splitting of the error function into two parts: the error from the time
discretization of the PDEs and the error from the finite element discretization
of corresponding time-discrete PDEs. The approach used in this paper is
applicable for more general nonlinear parabolic systems and many other
linearized (semi)-implicit time discretizations
Gender differentials in the payoff to schooling in rural China
This article examines the gender differential in the payoff to schooling in rural China. The analyses are based on a framework provided by the over education/required education/under education literature, and the decomposition developed by Chiswick and Miller (2008). It shows that the payoff to correctly matched education in rural China is much higher for females than for males. Associated with this, the wage penalty where workers are under qualified in their occupation is greater for females than for males. Over educated females, however, are advantaged compared with their male counterparts. These findings are interpreted using the explanations offered for the gender differential in the payoff to schooling in the growing literature on earnings determination in China
Dirac-Electrons-Mediated Magnetic Proximity Effect in Topological Insulator / Magnetic Insulator Heterostructures
The possible realization of dissipationless chiral edge current in a
topological insulator / magnetic insulator heterostructure is based on the
condition that the magnetic proximity exchange coupling at the interface is
dominated by the Dirac surface states of the topological insulator. Here we
report a polarized neutron reflectometry observation of Dirac electrons
mediated magnetic proximity effect in a bulk-insulating topological insulator
(BiSb)Te / magnetic insulator EuS heterostructure.
We are able to maximize the proximity induced magnetism by applying an
electrical back gate to tune the Fermi level of topological insulator to be
close to the charge neutral point. A phenomenological model based on
diamagnetic screening is developed to explain the suppressed proximity induced
magnetism at high carrier density. Our work paves the way to utilize the
magnetic proximity effect at the topological insulator/magnetic insulator
hetero-interface for low-power spintronic applications.Comment: 5 pages main text with 4 figures; 2 pages supplemental materials;
suggestions and discussions are welcome
Observation of the Quantum Anomalous Hall Insulator to Anderson Insulator Quantum Phase Transition and its Scaling Behavior
Fundamental insight into the nature of the quantum phase transition from a superconductor to an insulator in two dimensions, or from one plateau to the next or to an insulator in the quantum Hall effect, has been revealed through the study of its scaling behavior. Here, we report on the experimental observation of a quantum phase transition from a quantum-anomalous-Hall insulator to an Anderson insulator in a magnetic topological insulator by tuning the chemical potential. Our experiment demonstrates the existence of scaling behavior from which we extract the critical exponent for this quantum phase transition. We expect that our work will motivate much further investigation of many properties of quantum phase transition in this new context.STC Center for Integrated Quantum Materials (NSF Grant No. DMR-1231319)National Science Foundation (U.S.) (Grant DMR-1207469)National Science Foundation (U.S.) (Grant DMR- 0819762)United States. Office of Naval Research (Grant N00014-13-1- 0301)National Science Foundation (U.S.) (STC Center for Integrated Quantum Materials. Grant DMR-1231319
A Truncated IL‐17RC Peptide Ameliorates Synovitis and Bone Destruction of Arthritic Mice
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134880/1/adhm201600668_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134880/2/adhm201600668-sup-0001-S1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134880/3/adhm201600668.pd
Influenza A virus preferentially snatches noncoding RNA caps
Influenza A virus (IAV) lacks the enzyme for adding 5\u27 caps to its RNAs and snatches the 5\u27 ends of host capped RNAs to prime transcription. Neither the preference of the host RNA sequences snatched nor the effect of cap-snatching on host processes is completely defined. Previous studies of influenza cap-snatching used poly(A)-selected RNAs from infected cells or relied on annotated host genes to define the snatched host RNAs, and thus lack details on many noncoding host RNAs including snRNAs, snoRNAs, and promoter-associated capped small (cs)RNAs, which are made by paused Pol II during transcription initiation. In this study, we used a nonbiased technique, CapSeq, to identify host and viral-capped RNAs including nonpolyadenylated RNAs in the same samples, and investigated the substrate-product correlation between the host RNAs and the viral RNAs. We demonstrated that noncoding host RNAs, particularly U1 and U2, are the preferred cap-snatching source over mRNAs or pre-mRNAs. We also found that csRNAs are highly snatched by IAV. Because the functions of csRNAs remain mostly unknown, especially in somatic cells, our finding reveals that csRNAs at least play roles in the process of IAV infection. Our findings support a model where nascent RNAs including csRNAs are the preferred targets for cap-snatching by IAV and raise questions about how IAV might use snatching preferences to modulate host-mRNA splicing and transcription
Oxidation resistance of graphene-coated Cu and Cu/Ni alloy
The ability to protect refined metals from reactive environments is vital to
many industrial and academic applications. Current solutions, however,
typically introduce several negative effects, including increased thickness and
changes in the metal physical properties. In this paper, we demonstrate for the
first time the ability of graphene films grown by chemical vapor deposition to
protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy
from air oxidation. SEM, Raman spectroscopy, and XPS studies show that the
metal surface is well protected from oxidation even after heating at 200
\degree C in air for up to 4 hours. Our work further shows that graphene
provides effective resistance against hydrogen peroxide. This protection method
offers significant advantages and can be used on any metal that catalyzes
graphene growth
The FAST discovery of an Eclipsing Binary Millisecond Pulsar in the Globular Cluster M92 (NGC 6341)
We report the discovery of an eclipsing binary millisecond pulsar in the
globular cluster M92 (NGC6341) with the Five-hundred-meter Aperture Spherical
radio Telescope (FAST). PSR J1717+4308A, or M92A, has a pulse frequency of
316.5~Hz (3.16~ms) and a dispersion measure of 35.45 pc cm. The pulsar
is a member of a binary system with an orbital period of 0.20~days around a
low-mass companion which has a median mass of 0.18~\Ms. From observations
so far, at least two eclipsing events have been observed in each orbit. The
longer one lasted for ~5000~s in the orbital phase range 0.1--0.5. The other
lasted for ~500~s and occurred between 1000--2000~s before or after the longer
eclipsing event. The lengths of these two eclipsing events also change. These
properties suggest that J1717+4308A is a ``red-back'' system with a low-mass
main sequence or sub-giant companion. Timing observations of the pulsar and
further searches of the data for additional pulsars are ongoing.Comment: 9 pages, 2 figures, submitted to ApJL, comments are welcomed
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