2,833 research outputs found
Global exponential stability of classical solutions to the hydrodynamic model for semiconductors
In this paper, the global well-posedness and stability of classical solutions
to the multidimensional hydrodynamic model for semiconductors on the framework
of Besov space are considered. We weaken the regularity requirement of the
initial data, and improve some known results in Sobolev space. The local
existence of classical solutions to the Cauchy problem is obtained by the
regularized means and compactness argument. Using the high- and low- frequency
decomposition method, we prove the global exponential stability of classical
solutions (close to equilibrium). Furthermore, it is also shown that the
vorticity decays to zero exponentially in the 2D and 3D space. The main
analytic tools are the Littlewood-Paley decomposition and Bony's para-product
formula.Comment: 18 page
On the Origin of the Strong Optical Variability of Emission-line Galaxies
Emission-line galaxies (ELGs) are crucial in understanding the formation and
evolution of galaxies, while little is known about their variability. Here we
report the study on the optical variability of a sample of ELGs selected in the
COSMOS field, which has narrow-band observations in two epochs separated by
12 years. This sample was observed with Suprime-Cam (SC) and Hyper
Suprime-Cam (HSC) on the telescope in NB816 and bands,
respectively. After carefully removing the wing effect of a narrow-band filter,
we check the optical variability in a sample of 181 spectroscopically confirmed
ELGs. We find that 0 (0/68) Ha emitters, 11.9% (5/42) [OIII] emitters, and 0
(0/71) [OII] emitters show significant variability () in the two-epoch narrow-band
observations. We investigate the presence of active galactic nucleus (AGN) in
this variable ELG (var-ELG) sample with three methods, including X-ray
luminosity, mid-infrared activity, and radio-excess. We find zero bright AGN in
this var-ELG sample, but cannot rule out the contribution from faint AGN. We
find that SNe could also dominate the variability of the var-ELG sample. The
merger morphology shown in the HST/F814W images of all the var-ELG sample is in
agreement with the enhancement of star formation, i.e., the SNe activity.Comment: 20 pages, 10 figures, accepted for publication in The Astrophysical
Journa
Neural EGFL-Like 1 Regulates Cartilage Maturation through Runt-Related Transcription Factor 3–Mediated Indian Hedgehog Signaling
The pro-chondrogenic function of runt-related transcription factor 2 (Runx2) was previously considered to be dependent on direct binding with the promoter of Indian hedgehog (Ihh)—the major regulator of chondrocyte differentiation, proliferation, and maturation. The authors’ previous studies identified neural EGFL like 1 (Nell-1) as a Runx2-responsive growth factor for chondrogenic differentiation and maturation. In this study, it was further revealed that the pro-chondrogenic activities of Nell-1 also rely on Ihh signaling, by showing: i) Nell-1 significantly elevated Ihh signal transduction; ii) Nell-1 deficiency markedly reduced Ihh activation in chondrocytes; and iii) Nell-1–stimulated chondrogenesis was significantly reduced by the specific hedgehog inhibitor cyclopamine. Importantly, the authors demonstrated that Nell-1–responsive Ihh signaling and chondrogenic differentiation extended to Runx2 −/− models in vitro and in vivo. In Runx2 −/− chondrocytes, Nell-1 stimulated the expression and signal transduction of Runx3, another transcription factor required for complete chondrogenic differentiation and maturation. Furthermore, knocking down Runx3 in Runx2 −/− chondrocytes abolished Nell-1\u27s stimulation of Ihh-associated molecule expression, which validates Runx3 as a major mediator of Nell-1–stimulated Ihh activation. For the first time, the Runx2→Nell-1→Runx3→Ihh signaling cascade during chondrogenic differentiation and maturation has been identified as an alternative, but critical, pathway for Runx2 to function as a pro-chondrogenic molecule via Nell-1. © 2018 American Society for Investigative Patholog
The in Vitro Estrogenic Activities of Polyfluorinated Iodine Alkanes
Background: Polyfluorinated iodine alkanes (PFIs) are important intermediates in the synthesis of organic fluoride products. Recently, PFIs have been detected in fluoropolymers as residual raw materials, as well as in the ambient environment
Statistical Inference in a Directed Network Model with Covariates
Networks are often characterized by node heterogeneity for which nodes
exhibit different degrees of interaction and link homophily for which nodes
sharing common features tend to associate with each other. In this paper, we
propose a new directed network model to capture the former via node-specific
parametrization and the latter by incorporating covariates. In particular, this
model quantifies the extent of heterogeneity in terms of outgoingness and
incomingness of each node by different parameters, thus allowing the number of
heterogeneity parameters to be twice the number of nodes. We study the maximum
likelihood estimation of the model and establish the uniform consistency and
asymptotic normality of the resulting estimators. Numerical studies demonstrate
our theoretical findings and a data analysis confirms the usefulness of our
model.Comment: 29 pages. minor revisio
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Neural EGFL Like 1 as a Potential Pro-Chondrogenic, Anti-Inflammatory Dual-Functional Disease-Modifying Osteoarthritis Drug
Arthritis, an inflammatory condition that causes pain and cartilage destruction in joints, affects over 54.4 million people in the US alone. Here, for the first time, we demonstrated the emerging role of neural EGFL like 1 (NELL-1) in arthritis pathogenesis by showing that Nell-1-haploinsufficient (Nell-1+/6R) mice had accelerated and aggravated osteoarthritis (OA) progression with elevated inflammatory markers in both spontaneous primary OA and chemical-induced secondary OA models. In the chemical-induced OA model, intra-articular injection of interleukin (IL)1β induced more severe inflammation and cartilage degradation in the knee joints of Nell-1+/6R mice than in wildtype animals. Mechanistically, in addition to its pro-chondrogenic potency, NELL-1 also effectively suppressed the expression of inflammatory cytokines and their downstream cartilage catabolic enzymes by upregulating runt-related transcription factor (RUNX)1 in mouse and human articular cartilage chondrocytes. Notably, NELL-1 significantly reduced IL1β-stimulated inflammation and damage to articular cartilage in vivo. In particular, NELL-1 administration markedly reduced the symptoms of antalgic gait observed in IL1β-challenged Nell-1+/6R mice. Therefore, NELL-1 is a promising pro-chondrogenic, anti-inflammatory dual-functional disease-modifying osteoarthritis drug (DMOAD) candidate for preventing and suppressing arthritis-related cartilage damage. © 2019 Elsevier Lt
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Neural EGFL-Like 1 Is a Downstream Regulator of Runt-Related Transcription Factor 2 in Chondrogenic Differentiation and Maturation
Recent studies indicate that neural EGFL-like 1 (Nell-1), a secretive extracellular matrix molecule, is involved in chondrogenic differentiation. Herein, we demonstrated that Nell-1 serves as a key downstream target of runt-related transcription factor 2 (Runx2), a central regulator of chondrogenesis. Unlike in osteoblast lineage cells where Nell-1 and Runx2 demonstrate mutual regulation, further studies in chondrocytes revealed that Runx2 tightly regulates the expression of Nell-1; however, Nell-1 does not alter the expression of Runx2. More important, Nell-1 administration partially restored Runx2 deficiency–induced impairment of chondrocyte differentiation and maturation in vitro, ex vivo, and in vivo. Mechanistically, although the expression of Nell-1 is highly reliant on Runx2, the prochondrogenic function of Nell-1 persisted in Runx2−/− scenarios. The biopotency of Nell-1 is independent of the nuclear import and DNA binding functions of Runx2 during chondrogenesis. Nell-1 is a key functional mediator of chondrogenesis, thus opening up new possibilities for the application of Nell-1 in cartilage regeneration. © 2017 American Society for Investigative Patholog
Discovery of Five Green Pea Galaxies with Double-peaked Narrow [OIII] Lines
Although double-peaked narrow emission-line galaxies have been studied
extensively in the past years, only a few are reported with the green pea
galaxies (GPs). Here we present our discovery of five GPs with double-peaked
narrow [OIII] emission lines, referred to as DPGPs, selected from the LAMOST
and SDSS spectroscopic surveys. We find that these five DPGPs have blueshifted
narrow components more prominent than the redshifted components, with velocity
offsets of [OIII]5007 lines ranging from 306 to 518
and full widths at half maximums (FWHMs) of individual components ranging from
263 to 441 . By analyzing the spectra and the spectral energy
distributions (SEDs), we find that they have larger metallicities and stellar
masses compared with other GPs. The H line width, emission-line
diagnostic, mid-infrared color, radio emission, and SED fitting provide
evidence of the AGN activities in these DPGPs. They have the same spectral
properties of Type 2 quasars. Furthermore, we discuss the possible nature of
the double-peaked narrow emission-line profiles of these DPGPs and find that
they are more likely to be dual AGN. These DPGP galaxies are ideal laboratories
for exploring the growth mode of AGN in the extremely luminous emission-line
galaxies, the co-evolution between AGN and host galaxies, and the evolution of
high-redshift galaxies in the early Universe.Comment: 13 pages, 8 figures, 3 tables; Accepted for publication in MNRA
Diffusion Thermopower at Even Denominator Fractions
We compute the electron diffusion thermopower at compressible Quantum Hall
states corresponding to even denominator fractions in the framework of the
composite fermion approach. It is shown that the deviation from the linear low
temperature behavior of the termopower is dominated by the logarithmic
temperature corrections to the conductivity and not to the thermoelectric
coefficient, although such terms are present in both quantities. The enhanced
magnitude of this effect compared to the zero field case may allow its
observation with the existing experimental techniques.Comment: Latex, 12 pages, Nordita repor
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