29,331 research outputs found
Modes of zonal mean temperature variability 20–100 km from the TIMED/SABER observations
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
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
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
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
- …