484 research outputs found
Study on Law of Personnel Evacuation in Deep Buried Metro Station Based on the Characteristics of Fire Smoke Spreading
AbstractWith the improvement of people's life and the rapid development of urban traffic, the subway has the advantages of convenience and celerity, to a large extent, which greatly eases the traffic congestion phenomenon. With the attendant, the safety of the subway environment becomes vital. Many engineers focus on the study of the fire prevention and safety to escape. In this paper, a comprehensive study on the fire smoke spreading and the evacuation of the people in the deep buried metro model is carried out. First, the deep buried metro model is modeled on the STEPS software, and the personnel evacuation rule is obtained. According to the evacuation situation, the corresponding fire smoke monitoring points are built in the fire scenario which is set up on FDS+Evac software. Then, FDS+Evac program is used to simulate the evacuation in a fire scenario. It has not only analyzed the real time effect that the characteristics of fire smoke spread have on the personnel evacuation, but also improved the accuracy of the subway fire safety evaluation
The strong decay patterns of and states in the relativized quark model
Employing the relativized quark model and the quark-interchange model, we
investigate the decay of the charged heavy quarkonium-like states ,
, , and into the ground and
radially excited heavy quarkonia via emitting a pion meson. The and
states are assumed to be hadronic molecules composed of open-flavor heavy
mesons. The calculated decay ratios can be compared with the experimental data,
which are useful in judging whether the molecule state assignment for the
corresponding or state is reasonable or not. The theoretical
framework constructed in this work will be helpful in revealing the underlying
structures of some exotic hadrons.Comment: 19 pages, 4 figures, version published in EPJ
Experimental Decoy Quantum Key Distribution Up To 130KM Fiber
Decoy State Quantum Key Distribution (QKD), being capable of beating PNS
attack and uncon- ditionally secure, have become an attractive one recently.
But, in many QKD systems, disturbances of transmission channel make quantum bit
error rate (QBER) increase which limits both security distance and key bit rate
of real-life decoy state QKD systems. We demonstrate the two-intensity decoy
QKD with one-way Faraday-Michelson phase modulation system, which is free of
channel dis- turbance and keeps interference fringe visibility (99%) long
period, near 130KM single mode optical fiber in telecom (1550 nm) wavelength.
This is longest distance fiber decoy state QKD system based on two intensity
protocol.Comment: 4 pages, 2figure
Ethanol exposure leads to disorder of blood island formation in early chick embryo
Ethanol’s effect on embryonic vasculogenesis and its underlying mechanism is obscure. Using VE-cadherin in situ hybridization, we found blood islands formation was inhibited in area opaca, but abnormal VE-cadherin+ cells were seen in area pellucida. We hypothesise ethanol may affect blood island progenitor cell migration and differentiation. DiI and in vitro experiments revealed ethanol inhibited cell migration, Quantitative PCR analysis revealed that ethanol exposure enhanced cell differentiation in area pellucida of HH5 chick embryos and repressed cell differentiation in area pellucida of HH8 chick embryos. By exposing to 2,2′-azobis-amidinopropane dihydrochloride, a ROS inducer, which gave a similar anti-vasculogenesis effect as ethanol and this anti-vasculogenesis effect could be reversed by vitamin C. Overall, exposing early chick embryos to ethanol represses blood island progenitor cell migration but disturbed differentiation at a different stage, so that the disorder of blood island formation occurs through excess ROS production and altered vascular-associated gene expression
Tunable boson-assisted finite-range interaction and engineering Majorana corner modes in optical lattices
Nonlocal interaction between ultracold atoms trapped in optical lattices can
give rise to interesting quantum many-body phenomena. However, its realization
usually demands unconventional techniques, for example the artificial gauge
fields or higher-orbit Feshbach resonances, and is not highly controllable.
Here, we propose a valid and feasible scheme for realizing a tunable
finite-range interaction for spinless fermions immersed into the bath of
bosons. The strength of the effective interaction for the fermionic subsystem
is artificially tunable by manipulating bosons, ranging from the repulsive to
attractive regime. And the interaction distance is locked to the hopping of
bosons, making the finite-range interaction perfectly clean for the fermionic
subsystem. Specifically we find that, by introducing an additional staggered
hopping of bosons, the proposal is readily applied to search the Majorana
corner modes in such a spinless system, without implementation of complex
artificial gauge fields, which is totally distinct from existing results
reported in spinful systems. Therefore this scheme provides a potential
platform for exploring the unconventional topological superfluids and other
nontrivial phases induced by long-range interactions in ultracold atoms.Comment: 11 pages, 6 figure
Gate-tuned Aharonov-Bohm interference of surface states in a quasi-ballistic Dirac semimetal nanowire
We report an observation of a topologically protected transport of surface
carriers in a quasi-ballistic Cd3As2 nanowire.The nanowire is thin enough for
the spin-textured surface carriers to form 1D subbands, demonstrating
conductance oscillations with gate voltage even without magnetic field. The
{\pi} phase-shift of Aharonov-Bohm oscillations can periodically appear or
disappear by tuning gate voltage continuously. Such a {\pi} phase shift
stemming from the Berry's phase demonstrates the topological nature of surface
states.The topologically protected transport of the surface states is further
revealed by four-terminal nonlocal measurements.Comment: 15 pages, 4 figure
Phosphatase activities and available nutrients in soil aggregates affected by straw returning to a calcareous soil under the maize–wheat cropping system
The objective of this study was to investigate the effects of different rates of straw returning on soil aggregate stability, phosphatase activities, and the available nitrogen (N) and phosphorus (P) within different soil aggregate sizes. The experiment included five treatments: 1) no straw returning and no chemical fertilizer, 2) chemical fertilizer only (150 kg N ha-1, 75 kg P ha-1, and 75 kg K ha-1), 3) 20% straw returning with chemical fertilizer, 4) 60% straw returning with chemical fertilizer, and 5) 100% straw returning with chemical fertilizer. Soil samples were collected 3.5 years after the start of the experiment and separated into four aggregate sizes (<0.25 mm, 0.25–1 mm, 1–2 mm, and 2–7 mm) using the dry sieving method. Soil acid phosphomonoesterase (AcP) and alkaline phosphomonoesterase (AlP); phosphodiesterase (PD); pyrophosphatase (PrA) activities; and soil NO3−−N, NH4+−N, and resin-P were determined within soil aggregates. The results showed that straw returning rates did not significantly impact soil aggregate distribution. However, straw returning increased soil AcP, AlP, and PD in <2 mm aggregates, and high rates of straw returning led to high enzyme activities. Soil phosphatase activities were also higher in 1–2 mm aggregates. All straw returning and chemical fertilization treatments increased soil NO3−−N and resin-P concentrations but had much less effect on soil NH4+−N concentrations. Additionally, the study revealed that soil pH, the concentrations of NH4+−N, NO3−−N, resin-P, and CaCO3 significantly influenced soil phosphatase activities, but their impact varied across different sizes of aggregates
Loop-Mediated Isothermal Amplification Assay Targeting the MOMP Gene for Rapid Detection of Chlamydia psittaci Abortus Strain
For rapid detection of the Chlamydia psittaci abortus strain, a loop-mediated isothermal amplification (LAMP) assay was developed and evaluated in this study. The primers for the LAMP assay were designed on the basis of the main outer membrane protein (MOMP) gene sequence of C. psittaci. Analysis showed that the assay could detect the abortus strain of C. psittaci with adequate specificity. The sensitivity of the test was the same as that of the nested-conventional PCR and higher than that of chick embryo isolation. Testing of 153 samples indicated that the LAMP assay could detect the genome of the C. psittaci abortus strain effectively in clinical samples. This assay is a useful tool for rapid diagnosis of C. psittaci infection in sheep, swine and cattle
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