282 research outputs found

    The difference between individuals and social groups in multidirectional movement

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    Social groups exhibit some degree of social cohesion that is more than a simple collection or aggregation of individuals. The study on behaviours of social groups is essential to gain a deeper understanding on pedestrian dynamics. In this paper, the crowd movement among individuals and social groups are studied by performing a series of multidirectional pedestrian flow experiments under laboratory condition. Interestingly, we found that the speed of individual is not always higher than that of social groups. Pedestrians try to use different strategies to arrive their destination. With different strategies, their speed and movement time show different properties. These findings may provide basis for facility design and evacuation plan

    Structural reliability and its sensitivity analysis based on the saddlepoint approximation-line sampling method by dichotomy of golden section

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    In order to solve the structural reliability and its sensitivity of the implicit nonlinear performance function (PF)  the advantages of the saddlepoint approximation (SA) and line sampling (LS) are merged. Also, the merits of dichotomy and the solution efficiency of the golden section method are combined to propose the saddlepoint approximation-line sampling (SA-LS) method based on the dichotomy of the golden section point. This is complicated and changeable in the non normal variable space, which is a very hot issue of the present international study.  For each sample, it is quick to find its zeropoint in PF along the important line sampling direction by the  previously mentioned dichotomy so that the structural failure probability can be transformed into the mean of a series linear PFs failure probability, and the reliability sensitivity is just the derivative or partial one of the probability with respect to the relational variables. Examples show that the SA-LS method based on the dichotomy of the golden section point is of high precision and fast velocity in analyzing the structural reliability and sensitivity of the implicit nonlinear PF that are complicated and changeable in the non-normal variable space

    Evacuation characteristics of preschool children through bottlenecks

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    Pedestrian movement through bottlenecks have been widely studied from various aspects to understand the effects of bottlenecks on the pedestrian flow. However, few attentions have been paid to the movement characteristics of preschool children, who show obvious differences behaviour compared to adults due to the poor balance and understanding of danger especial under emergencies. In this study, we focus on the evacuation characteristics of preschool children through bottlenecks with laboratory experiments. From all the experiment, we do not observe clear lane formation process from the trajectories diagrams. It is found that the first arrive first out principle does not work in the situation with competition. Compared to adults, children are more likely to fall and hard to be controlled during movement, which is very dangerous in emergencies. The highest speed for the preschool children can beyond 3 m/s and is depend on the location in the crowd for each individual. For a given number of evacuees, the total evacuation time firstly decreases a linear with the increasing the bottleneck width and then keeps a constant if nobody falls down during the movement. Falling down of children will increase the evacuation time incredibly. The findings will be beneficial for the evacuation drill design in kindergarten as well as the facility design for young children

    Influences of phase transition and microstructure on dielectric properties of Bi0.5Na0.5Zr1-xTixO3 ceramics

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    Bismuth sodium zirconate titanate ceramics with the formula Bi0.5Na0.5Zr1-xTixO3 [BNZT], where x = 0.3, 0.4, 0.5, and 0.6, were prepared by a conventional solid-state sintering method. Phase identification was investigated using an X-ray diffraction technique. All compositions exhibited complete solubility of Ti4+ at the Zr4+ site. Both a decrease of unit cell size and phase transition from an orthorhombic Zr-rich composition to a rhombohedral crystal structure in a Ti-rich composition were observed as a result of Ti4+ substitution. These changes caused dielectric properties of BNZT ceramics to enhance. Microstructural observation carried out employing SEM showed that average grain size decreased when addition of Ti increased. Grain size difference of BNZT above 0.4 mole fraction of Ti4+ displayed a significant increase of dielectric constant at room temperature

    A Prospective Study of the Surgical Outcome of Simple Uvulopalatopharyngoplasty (UPPP), UPPP Combined With Genioglossus Advancement or Tongue Base Advancement for Obstructive Sleep Apnea Hypopnea Syndrome Patients With Multilevel Obstruction

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    ObjectivesTo investigate the surgical outcomes of different uvulopalatopharyngoplasty (UPPP).Methods All subjects underwent overnight polysomnography and were evaluated using the Epworth sleepiness scale (ESS), the Quebec sleep questionnaire and the snoring scale at the baseline and 3 and 12 months following operation. The primary endpoint was the overall effective rate representing the sum of the surgical success rate and effective rate.ResultsThe overall effective rate at 12 months post surgery was 55.6% for simple UPPP, 95.8% for UPPP+GA, and 92.3% for UPPP+TBA. The surgical success rate at 3 and 12 months postoperation for UPPP+GA or UPPP+TBA was significantly higher than simple UPPP (P<0.05). Marked improvement was observed in all patients in the snoring scale score and the ESS score 3 and 12 months following surgery compared to the baseline (P<0.05 in all).ConclusionUPPP, UPPP+GA, and UPPP+TBA are all effective in improving the surgical outcome of obstructive sleep apnea hypopnea syndrome (OSAHS) patients with multilevel obstruction. UPPP+TBA appears to be the most effective in treating OSAHS patients

    Genomic Analyses Reveal Mutational Signatures and Frequently Altered Genes in Esophageal Squamous Cell Carcinoma

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    Esophageal squamous cell carcinoma (ESCC) is one of the most common cancers worldwide and the fourth most lethal cancer in China. However, although genomic studies have identified some mutations associated with ESCC, we know little of the mutational processes responsible. To identify genome-wide mutational signatures, we performed either whole-genome sequencing (WGS) or whole-exome sequencing (WES) on 104 ESCC individuals and combined our data with those of 88 previously reported samples. An APOBEC-mediated mutational signature in 47% of 192 tumors suggests that APOBEC-catalyzed deamination provides a source of DNA damage in ESCC. Moreover, PIK3CA hotspot mutations (c.1624G>A [p.Glu542Lys] and c.1633G>A [p.Glu545Lys]) were enriched in APOBEC-signature tumors, and no smoking-associated signature was observed in ESCC. In the samples analyzed by WGS, we identified focal (<100 kb) amplifications of CBX4 and CBX8. In our combined cohort, we identified frequent inactivating mutations in AJUBA, ZNF750, and PTCH1 and the chromatin-remodeling genes CREBBP and BAP1, in addition to known mutations. Functional analyses suggest roles for several genes (CBX4, CBX8, AJUBA, and ZNF750) in ESCC. Notably, high activity of hedgehog signaling and the PI3K pathway in approximately 60% of 104 ESCC tumors indicates that therapies targeting these pathways might be particularly promising strategies for ESCC. Collectively, our data provide comprehensive insights into the mutational signatures of ESCC and identify markers for early diagnosis and potential therapeutic targets
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