1,467 research outputs found
Spectral conditions for a graph to be Hamilton-connected
In this paper we establish some spectral conditions for a graph to be
Hamilton-connected in terms of the spectral radius of the adjacency matrix or
the signless Laplacian of the graph or its complement. For the existence of
Hamiltonian paths or cycles in a graph, we also give a sufficient condition by
the signless Laplacian spectral radius
Limiting Magnitudes of the Wide Field Survey Telescope (WFST)
Expected to be of the highest survey power telescope in the northern
hemisphere, the Wide Field Survey Telescope (WFST) will begin its routine
observations of the northern sky since 2023. WFST will produce a lot of
scientific data to support the researches of time-domain astronomy, asteroids
and the solar system, galaxy formation and cosmology and so on. We estimated
that the 5 limiting magnitudes of WFST with 30 second exposure are
mag, mag, mag, mag, mag,
mag. The above values are calculated for the conditions of
, seeing = 0.75 arcsec, precipitable water vapour (PWV) = 2.5 mm
and Moon-object separation = at the darkest New Moon night of the
Lenghu site (V=22.30 mag, Moon phase ). The limiting
magnitudes in different Moon phase conditions are also calculated. The
calculations are based on the empirical transmittance data of WFST optics, the
vendor provided CCD quantum efficiency, the atmospherical model transmittance
and spectrum of the site. In the absence of measurement data such as sky
transmittance and spectrum, we use model data.Comment: 12 pages, 5 figures, accepted by RAA (Research in Astronomy and
Astrophysics
Genome-wide analysis and identification of microRNAs in Medicago truncatula under aluminum stress
Numerous studies have shown that plant microRNAs (miRNAs) play key roles in plant growth and development, as well as in response to biotic and abiotic stresses; however, the role of miRNA in legumes under aluminum (Al) stress have rarely been reported. Therefore, here, we aimed to investigate the role of miRNAs in and their mechanism of Al tolerance in legumes. To this end, we sequenced a 12-strand-specific library of Medicago truncatula under Al stress. A total of 195.80 M clean reads were obtained, and 876 miRNAs were identified, of which, 673 were known miRNAs and 203 were unknown. A total of 55 miRNAs and their corresponding 2,502 target genes were differentially expressed at various time points during Al stress. Further analysis revealed that mtr-miR156g-3p was the only miRNA that was significantly upregulated at all time points under Al stress and could directly regulate the expression of genes associated with root cell growth. Three miRNAs, novel_miR_135, novel_miR_182, and novel_miR_36, simultaneously regulated the expression of four Al-tolerant transcription factors, GRAS, MYB, WRKY, and bHLH, at an early stage of Al stress, indicating a response to Al stress. In addition, legume-specific miR2119 and miR5213 were involved in the tolerance mechanism to Al stress by regulating F-box proteins that have protective effects against stress. Our results contribute to an improved understanding of the role of miRNAs in Al stress in legumes and provide a basis for studying the molecular mechanisms of Al stress regulation
Flexible Coherent Optical Access: Architectures, Algorithms, and Demonstrations
To cope with the explosive bandwidth demand, significant progress has been
made in the ITU-T standardization sector to define a higher-speed passive
optical network (PON) with a 50Gb/s line rate. Recently, 50G PON becomes mature
gradually, which means it is time to discuss beyond 50G PON. For ensuring an
acceptable optical power budget, beyond 50G PON will potentially use coherent
technologies, which can simultaneously promote the applications of flexible
multiple access such as time/frequency-domain multiple access (TFDMA). In this
paper, we will introduce the architectures, algorithms, and demonstrations for
TFDMA-based coherent PON. The system architectures based on an ultra-simple
coherent transceiver and specific signal spectra are designed to greatly reduce
the cost of ONUs. Meanwhile, fast and low-complexity digital signal processing
(DSP) algorithms are proposed for dealing with upstream and downstream signals.
Based on the architectures and algorithms, we experimentally demonstrate the
first real-time TFDMA-based coherent PON, which can support at most 256 end
users, and peak line rates of 100Gb/s and 200Gb/s in the upstream and
downstream scenarios, respectively. In conclusion, the proposed technologies
for the coherent PON make it more possible to be applied in the future beyond
50G PON.Comment: The paper has been submitted to the Journal of Lightwave Technolog
Temperature-dependent striped antiferromagnetism of LaFeAsO in a Green's function approach
We use a Green's function method to study the temperature-dependent average
moment and magnetic phase-transition temperature of the striped
antiferromagnetism of LaFeAsO, and other similar compounds, as the parents of
FeAs-based superconductors. We consider the nearest and the next-nearest
couplings in the FeAs layer, and the nearest coupling for inter-layer spin
interaction. The dependence of the transition temperature TN and the
zero-temperature average spin on the interaction constants is investigated. We
obtain an analytical expression for TN and determine our temperature-dependent
average spin from zero temperature to TN in terms of unified self-consistent
equations. For LaFeAsO, we obtain a reasonable estimation of the coupling
interactions with the experimental transition temperature TN = 138 K. Our
results also show that a non-zero antiferromagnetic (AFM) inter-layer coupling
is essential for the existence of a non-zero TN, and the many-body AFM
fluctuations reduce substantially the low-temperature magnetic moment per Fe
towards the experimental value. Our Green's function approach can be used for
other FeAs-based parent compounds and these results should be useful to
understand the physical properties of FeAs-based superconductors.Comment: 12 page
(5R)-5-hydroxytriptolide inhibits the inflammatory cascade reaction in astrocytes
Many studies have shown that (5R)-5-hydroxytriptolide is the optimal modified analogue of triptolide, possessing comparable immunosuppressive activity but much lower cytotoxicity than triptolide. Whether (5R)-5-hydroxytriptolide has preventive effects on neuroinflammation is unclear. This study was designed to pretreat primary astrocytes from the brains of neonatal Sprague-Dawley rats with 20, 100 and 500 nM (5R)-5-hydroxytriptolide for 1 hour before establishing an in vitro neuroinflammation model with 1.0 μg/mL lipopolysaccharide for 24 hours. The generation of nitric oxide was detected by Griess reagents. Astrocyte marker glial fibrillary acidic protein was measured by immunohistochemical staining. The levels of tumor necrosis factor-α and interleukin-1β in the culture supernatant were assayed by enzyme linked immunosorbent assay. Nuclear factor-κB/p65 expression was examined by immunofluorescence staining. The phosphorylation of inhibitor of nuclear factor IκB-α and the location of nuclear factor-κB/P65 were determined using western blot assay. Our data revealed that (5R)-5-hydroxytriptolide inhibited the generation of nitric oxide, tumor necrosis factor-α and interleukin-1β from primary astrocytes activated by lipopolysaccharide, decreased the positive reaction intensity of glial fibrillary acidic protein, reduced the expression of tumor necrosis factor alpha and interleukin-1β in culture supernatant, inhibited the phosphorylation of IκB-α and the translocation of nuclear factor-κB/P65 to the nucleus. These results have confirmed that (5R)-5-hydroxytriptolide inhibits lipopolysaccharide-induced glial inflammatory response and provides cytological experimental data for (5R)-5-hydroxytriptolide in the treatment of neurodegenerative diseases
EMMNet: Sensor Networking for Electricity Meter Monitoring
Smart sensors are emerging as a promising technology for a large number of application domains. This paper presents a collection of requirements and guidelines that serve as a basis for a general smart sensor architecture to monitor electricity meters. It also presents an electricity meter monitoring network, named EMMNet, comprised of data collectors, data concentrators, hand-held devices, a centralized server, and clients. EMMNet provides long-distance communication capabilities, which make it suitable suitable for complex urban environments. In addition, the operational cost of EMMNet is low, compared with other existing remote meter monitoring systems based on GPRS. A new dynamic tree protocol based on the application requirements which can significantly improve the reliability of the network is also proposed. We are currently conducting tests on five networks and investigating network problems for further improvements. Evaluation results indicate that EMMNet enhances the efficiency and accuracy in the reading, recording, and calibration of electricity meters
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