29,618 research outputs found

    Modes of zonal mean temperature variability 20–100 km from the TIMED/SABER observations

    Get PDF
    In this study we investigate the spatial variabilities of the zonal mean temperature (20–100 km) from the TIMED (Thermosphere, Ionosphere, Mesosphere, Energetics and Dynamics)/SABER (Sounding of the Atmosphere using Broadband Emission Radiometry) satellite using the empirical orthogonal functions (EOFs). After removing the climatological annual mean, the first three EOFs are able to explain 87.0% of temperature variabilities. The primary EOF represents 74.1% of total anomalies and is dominated by the north–south contrast. Patterns in the second and third EOFs are related to the semiannual oscillations (SAO) and mesospheric temperature inversions (MTI), respectively. The quasi-biennial oscillation (QBO) component is also decomposed into the seventh EOF with contributions of 1.2%. Last, we use the first three modes and annual mean temperature to reconstruct the data. The result shows small differences are in low latitude, which increase with latitude in the middle stratosphere and upper mesosphere

    Temperature dependence of electron-spin relaxation in a single InAs quantum dot at zero applied magnetic field

    Full text link
    The temperature-dependent electron spin relaxation of positively charged excitons in a single InAs quantum dot (QD) was measured by time-resolved photoluminescence spectroscopy at zero applied magnetic fields. The experimental results show that the electron-spin relaxation is clearly divided into two different temperature regimes: (i) T < 50 K, spin relaxation depends on the dynamical nuclear spin polarization (DNSP) and is approximately temperature-independent, as predicted by Merkulov et al. (ii) T > about 50 K, spin relaxation speeds up with increasing temperature. A model of two LO phonon scattering process coupled with hyperfine interaction is proposed to account for the accelerated electron spin relaxation at higher temperatures.Comment: 10 pages, 4 figure

    Fabrication and characterizations of proton-exchanged LiNbO3 waveguides fabricated by inductively coupled plasma technique

    Get PDF
    This Letter reports the use of an inductively coupled plasma technique for fabrication of proton-exchanged (PE) LiNbO3 (LN) waveguides. Planar and stripe waveguides have been formed in Y-cut LN which are difficult to obtain with the conventional molten acid method due to the occurrence of surface damage. Secondary ion mass spectrometry, scanning electron microscopy, and infrared absorption spectrum characterization results revealed that a uniform vertical PE profile with a single low order crystal phase has been directly obtained as a result of this unique process. X-ray photoelectron spectroscopy characterization of the treated surface revealed the existence of NbO as the cause for a sometimes darkened surface and confirms the ability to completely restore the surface to LN by oxygen plasma treatment. Atomic force microscopy measurement confirms that good surface quality has been maintained after regeneration of the surface to LN

    TRED: a transcriptional regulatory element database, new entries and other development

    Get PDF
    Transcriptional factors (TFs) and many of their target genes are involved in gene regulation at the level of transcription. To decipher gene regulatory networks (GRNs) we require a comprehensive and accurate knowledge of transcriptional regulatory elements. TRED () was designed as a resource for gene regulation and function studies. It collects mammalian cis- and trans-regulatory elements together with experimental evidence. All the regulatory elements were mapped on to the assembled genomes. In this new release, we included a total of 36 TF families involved in cancer. Accordingly, the number of target promoters and genes for TF families has increased dramatically. There are 11 660 target genes (7479 in human, 2691 in mouse and 1490 in rat) and 14 908 target promoters (10 225 in human, 2985 in mouse and 1698 in rat). Additionally, we constructed GRNs for each TF family by connecting the TF–target gene pairs. Such interaction data between TFs and their target genes will assist detailed functional studies and help to obtain a panoramic view of the GRNs for cancer research

    Does high-quality financial reporting mitigate the negative impact of global financial crises on firm performance? Evidence from the United Kingdom

    Get PDF
    © 2015 Australasian Accounting Business and Finance Journal and Authors. Prior literature has claimed that accounting plays a negative role in a financial crisis. The current study sought to determine whether this effect is dependent on the quality of financial reporting. Specifically, this study examined the impact of the quality of financial reporting (as measured via earnings quality) on liquidity (measured by the bid-ask spread) in the equity market during the 2008–2009 global financial crisis in the United Kingdom. We found, as expected, that market liquidity was much lower during the crisis than prior to the crisis; however, firms with high-quality financial reporting suffered fewer negative effects as a result of the financial crisis. The results were robust after controlling for other influences, such as return volatility, loss making, market value of equity, and other potential endogeneity problems. In addition, adopting alternative models for earnings quality did not alter our inferences. Our results support the notion that high-quality accounting information can reduce information asymmetry and hence enhance investor confidence during a financial crisis. The results suggest that a stable financial reporting system is an important part of that overall economic fabric. Our findings will help build a framework on which an overall financial crisis risk-management strategy can be developed to avoid future crises
    • …
    corecore