2,931 research outputs found
A New Calculation Model of Detection Time for Heat Detector in Long and Narrow Space
AbstractFire detector plays an important role in ship fire safety system. Usually, there are two types of fire detectors including fire smoke detector and heat detector, which are widely used in exit passageway, corridor, ladderway, and other long and narrow spaces in ship. Due to the smoke plume characteristics in these limited spaces are different to that of free plume in open place, the detection time calculating model of heat detector for these two different conditions are consequently different. This work is to develop a new detection time calculating model based on the fire plume rules including characteristics of temperature and velocity of fire smoke distributing in long and narrow spaces. Numeric method for calculating detection time is also presented. Finally, some calculations and analysis for a given fire scenario are performed. The numeric results are compared with that of the existing detection time calculating model based on free plume theory, which demonstrate the applicability of the model proposed in this article
The Tissue Response and Degradation of Electrospun Poly( ε
Due to the advantage of controllability on the mechanical property and the degradation rates, electrospun PCL/PTMC nanofibrous scaffold could be appropriate for vascular tissue engineering. However, the tissue response and degradation of electrospun PCL/PTMC scaffold in vivo have never been evaluated in detail. So, electrospun PCL/PTMC scaffolds with different blend ratios were prepared in this study. Mice subcutaneous implantation showed that the continuous degradation of PCL/PTMC scaffolds induced a lasted macrophage-mediated foreign body reaction, which could be in favor of the tissue regeneration in graft
1,3-Diprop-2-ynyl-1H-imidazol-3-ium bromide
In the title salt, C9H9N2
+·Br−, the ethynyl groups are nearly antiparallel to each other [the angle between the two ethynyl groups is179.7 (2)°]. No classical hydrogen bonds or π–π interactions are observed. The molecules are linked by C—H⋯Br hydrogen bonds. The bromide anions are involved in interactions with three H atoms
DEFB1 rs11362 Polymorphism and Risk of Chronic Periodontitis: A Meta-Analysis of Unadjusted and Adjusted Data
Objective: Chronic periodontitis (CP) is a growing problem that affects the worldwide population, having significant impacts on people's daily lives and economic development. Genetics is an important component in the determination of individual susceptibility to periodontal diseases. Numerous studies have been performed to investigate the association between beta defensin 1 (DEFB1) rs11362 polymorphism and risk of CP, but the results are still inconclusive. Therefore, we conducted this meta-analysis to ascertain whether this variation in DEFB1 is associated with CP susceptibility.Methods: The relevant studies were searched in PubMed and Chinese National Knowledge Infrastructure (CNKI) databases up to January 9, 2018. Two independent authors selected citations and extracted the data from eligible studies. Odds ratios (ORs) with their 95% confidence intervals (95% CIs) were used to assess the strength of the association.Results: Seven case-control studies were included in this meta-analysis. Based on unadjusted data, there was no obvious association between DEFB1 rs11362 polymorphism and CP risk in all genetic models (A vs. G: OR = 0.86, 95%CI = 0.61–1.20; AA vs. GG: OR = 0.83, 95% CI = 00.50–1.39; AG vs. GG: OR = 1.01, 95%CI = 0.73–1.39; AG+AA vs. GG: OR = 0.91, 95% CI = 00.74–1.11; and AA vs. AG+GG: OR = 0.83, 95% CI = 00.57–1.21); the results of adjusted data also showed no significant relationship. Subgroup analyses based on ethnicity, participants' smoking status, HWE in controls and severity of CP all revealed similar results to that of the overall analysis. Sensitivity analysis indicated the results were robust and no evidence of publication bias was found.Conclusions: Our meta-analysis suggests that DEFB1 rs11362 polymorphism may not have an important effect on the risk of CP. Further large-scale and well-designed studies are necessary to validate our conclusion in the future
Empirical study on clique-degree distribution of networks
The community structure and motif-modular-network hierarchy are of great
importance for understanding the relationship between structures and functions.
In this paper, we investigate the distribution of clique-degree, which is an
extension of degree and can be used to measure the density of cliques in
networks. The empirical studies indicate the extensive existence of power-law
clique-degree distributions in various real networks, and the power-law
exponent decreases with the increasing of clique size.Comment: 9 figures, 4 page
Optical and Gamma-Ray Variability Behaviors of 3C 454.3 from 2006 to 2011
We present our photometric monitoring of a flat spectrum radio quasar (FSRQ)
3C 454.3 at Yunnan observatories from 2006 to 2011. We find that the optical
color of 3C 454.3 shows obvious redder-when-brighter trend, which reaches a
saturation stage when the source is brighter than 15.15 mag at V band. We
perform a simulation with multiple values of disk luminosity and spectral index
to reproduce the magnitude-color diagram. The results show that the
contamination caused by the disk radiation alone is difficult to produce the
observed color variability. The variability properties during the outburst in
December 2009 are also compared with -ray data derived from Fermi
-ray space telescope. The flux variation of these two bands follow a
linear relation with , which provides an
observational evidence for external Compton process in 3C 454.3. Meanwhile,
this flux correlation indicates that electron injection is the main mechanism
for variability origin. We also explore the variation of the flux ratio
and the detailed structures in the lightcurves, and discuss
some possible origins for the detailed variability behaviors.Comment: accepted for publication in The Astrophysical Journal, 5 figures, 2
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