24,537 research outputs found

    Hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells

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    We study the hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells. The corresponding polariton states are given. The analytical solution and the numerical result of the stationary spectrum for the cavity field are finishedComment: 3 pages, 1 figure. appear in Communications in Theoretical Physic

    KDM2B/FBXL10 targets c-Fos for ubiquitylation and degradation in response to mitogenic stimulation.

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    KDM2B (also known as FBXL10) controls stem cell self-renewal, somatic cell reprogramming and senescence, and tumorigenesis. KDM2B contains multiple functional domains, including a JmjC domain that catalyzes H3K36 demethylation and a CxxC zinc-finger that recognizes CpG islands and recruits the polycomb repressive complex 1. Here, we report that KDM2B, via its F-box domain, functions as a subunit of the CUL1-RING ubiquitin ligase (CRL1/SCF(KDM2B)) complex. KDM2B targets c-Fos for polyubiquitylation and regulates c-Fos protein levels. Unlike the phosphorylation of other SCF (SKP1-CUL1-F-box)/CRL1 substrates that promotes substrates binding to F-box, epidermal growth factor (EGF)-induced c-Fos S374 phosphorylation dissociates c-Fos from KDM2B and stabilizes c-Fos protein. Non-phosphorylatable and phosphomimetic mutations at S374 result in c-Fos protein which cannot be induced by EGF or accumulates constitutively and lead to decreased or increased cell proliferation, respectively. Multiple tumor-derived KDM2B mutations impaired the function of KDM2B to target c-Fos degradation and to suppress cell proliferation. These results reveal a novel function of KDM2B in the negative regulation of cell proliferation by assembling an E3 ligase to targeting c-Fos protein degradation that is antagonized by mitogenic stimulations

    The Physical Connections Among IR QSOs, PG QSOs and Narrow-Line Seyfert 1 Galaxies

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    We study the properties of infrared-selected QSOs (IR QSOs), optically-selected QSOs (PG QSOs) and Narrow Line Seyfert 1 galaxies (NLS1s). We compare their properties from the infrared to the optical and examine various correlations among the black hole mass, accretion rate, star formation rate and optical and infrared luminosities. We find that the infrared excess in IR QSOs is mostly in the far infrared, and their infrared spectral indices suggest that the excess emission is from low temperature dust heated by starbursts rather than AGNs. The infrared excess is therefore a useful criterion to separate the relative contributions of starbursts and AGNs. We further find a tight correlation between the star formation rate and the accretion rate of central AGNs for IR QSOs. The ratio of the star formation rate and the accretion rate is about several hundred for IR QSOs, but decreases with the central black hole mass. This shows that the tight correlation between the stellar mass and the central black hole mass is preserved in massive starbursts during violent mergers. We suggest that the higher Eddington ratios of NLS1s and IR QSOs imply that they are in the early stage of evolution toward classical Seyfert 1's and QSOs, respectively.Comment: 32 pages, 6 figures, accepted by Ap

    Momentum Distribution of Near-Zero-Energy Photoelectrons in the Strong-Field Tunneling Ionization in the Long Wavelength Limit

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    We investigate the ionization dynamics of Argon atoms irradiated by an ultrashort intense laser of a wavelength up to 3100 nm, addressing the momentum distribution of the photoelectrons with near-zero-energy. We find a surprising accumulation in the momentum distribution corresponding to meV energy and a \textquotedblleft V"-like structure at the slightly larger transverse momenta. Semiclassical simulations indicate the crucial role of the Coulomb attraction between the escaping electron and the remaining ion at extremely large distance. Tracing back classical trajectories, we find the tunneling electrons born in a certain window of the field phase and transverse velocity are responsible for the striking accumulation. Our theoretical results are consistent with recent meV-resolved high-precision measurements.Comment: 5 pages, 4 figure

    The Focal Heat Flux Distribution Measurement of High-times Concentrating Directional Transmission System

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    The concentrating performance of solar energy plays an important role in its application at high temperature. Recently, High-times Concentrating Directional Transmission System (CDTS) was built in the authors’ laboratory. To evaluate the focal flux distribution of a solar concentrator, a kind of measurement system was established, in which an infrared camera and several thermocouples along with a heat flow meter were employed, and the clear heat flux distribution of focal spot was obtained. The skew ray tracing principle was used to simulate the process of solar energy transmission and compared with the test results. Keywords: measurement and instrument, CDTS, heat flux distribution, skew ray tracing principl

    Thermal Performance Analysis of High-temperature Heat Transfer Process of Solar Energy

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    Volumetric solar receivers (VSR) have become a promising technology for the solar thermal conversion. The absorption of the concentrated solar radiation and the heat transfer to the working fluid are the two dominant processes. Firstly, the effects of two typical modeling approaches of the concentrated solar radiation for receiver are compared in view of porosity and mean cell size. Then, the radiation transport within the solar window and the porous absorber is fully simulated. The effects of porous structure parameters, slope error of the concentrator, and the alignment error of the receiver are analyzed. Keywords: volumetric solar receivers (VSR), Monte Carlo ray tracing method, concentrated solar radiation, heat transfe

    Luminous Infrared Galaxies in the Local Universe

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    We study the morphology and star formation properties of 159 local luminous infrared galaxy (LIRG) using multi-color images from Data Release 2 (DR2) of the Sloan Digital Sky Survey (SDSS). The LIRGs are selected from a cross-correlation analysis between the IRAS survey and SDSS. They are all brighter than 15.9 mag in the r-band and below redshift ~ 0.1, and so can be reliably classified morphologically. We find that the fractions of interacting/merging and spiral galaxies are ~ 48% and ~ 40% respectively. Our results complement and confirm the decline (increase) in the fraction of spiral (interacting/merging) galaxies from z ~1 to z ~ 0.1, as found by Melbourne, Koo & Le Floc'h (2005). About 75% of spiral galaxies in the local LIRGs are barred, indicating that bars may play an important role in triggering star formation rates > 20 M_{sun}/yr in the local universe. Compared with high redshift LIRGs, local LIRGs have lower specific star formation rates, smaller cold gas fractions and a narrower range of stellar masses. Local LIRGs appear to be either merging galaxies forming intermediate mass ellipticals or spiral galaxies undergoing high star formation activities regulated by bars.Comment: 22 pages, 5 figures, accepted for publication in ApJ, title changed, typos corrected,major revisions following referee's comments,updated reference

    The Properties of H{\alpha} Emission-Line Galaxies at z = 2.24

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    Using deep narrow-band H2S1H_2S1 and KsK_{s}-band imaging data obtained with CFHT/WIRCam, we identify a sample of 56 Hα\alpha emission-line galaxies (ELGs) at z=2.24z=2.24 with the 5σ\sigma depths of H2S1=22.8H_2S1=22.8 and Ks=24.8K_{s}=24.8 (AB) over 383 arcmin2^{2} area in the ECDFS. A detailed analysis is carried out with existing multi-wavelength data in this field. Three of the 56 Hα\alpha ELGs are detected in Chandra 4 Ms X-ray observation and two of them are classified as AGNs. The rest-frame UV and optical morphologies revealed by HST/ACS and WFC3 deep images show that nearly half of the Hα\alpha ELGs are either merging systems or with a close companion, indicating that the merging/interacting processes play a key role in regulating star formation at cosmic epoch z=2-3; About 14% are too faint to be resolved in the rest-frame UV morphology due to high dust extinction. We estimate dust extinction from SEDs. We find that dust extinction is generally correlated with Hα\alpha luminosity and stellar mass (SM). Our results suggest that Hα\alpha ELGs are representative of star-forming galaxies (SFGs). Applying extinction correction for individual objects, we examine the intrinsic Hα\alpha luminosity function (LF) at z=2.24z=2.24, obtaining a best-fit Schechter function characterized by a faint-end slope of α=1.3\alpha=-1.3. This is shallower than the typical slope of α1.6\alpha \sim -1.6 in previous works based on constant extinction correction. We demonstrate that this difference is mainly due to the different extinction corrections. The proper extinction correction is thus key to recovering the intrinsic LF as the extinction globally increases with Hα\alpha luminosity. Moreover, we find that our Hα\alpha LF mirrors the SM function of SFGs at the same cosmic epoch. This finding indeed reflects the tight correlation between SFR and SM for the SFGs, i.e., the so-called main sequence.Comment: 15 pages, 12 figures, 2 tables, Received 2013 October 11; accepted 2014 February 13; published 2014 March 18 by Ap
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