679 research outputs found

    Indirect coupling method for structural analysis of refuge chamber

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    Structural analysis is important in the design of a refuge chamber, which can ensure the structural safety of the refuge chamber in case of an explosion. In this paper, an indirect coupling method is utilized to calculate deformation of a refuge chamber under explosion, when gas explosion is simulated in a roadway model, and the pressure waves on different locations of chamber are extracted. The extracted pressure-time curves are applied to a detailed model of the refuge chamber to obtain deformation values. However, reliabilities and validities of the simulation results are not provided. Thereby, we conducted three groups of small-scale physical experiments for comparing the corresponding simulation results calculated by the indirect coupling method. Meanwhile, the theoretical values were obtained by the method of extracting the specific impulse. The results show that the simulation values fit well with the experimental and theoretical values. The process of applying a pressure-time curve to the model covers the specific impulse which acts on the prototype. This method can be used to calculate the deformation of complex equipment under explosion

    Population Differences in the Polyalanine Domain and 6 New Mutations in HLXB9 in Patients with Currarino Syndrome

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    Abstract Background: The combination of partial absence of the sacrum, anorectal anomalies, and presacral mass constitutes Currarino syndrome (CS), which is associated with mutations in HLXB9. Methods: We analyzed 5 CS families and 6 sporadic cases for HLXB9 mutations by direct sequencing. Potentially pathologic expansions of HLXB9 GCC repeats were analyzed in patients, 4 general populations [Chinese, Japanese, Yoruba, and Centre du Etude Polymorphisme Human (CEPH)] from the HapMap project, and 145 healthy Chinese. Results: We identified 6 novel mutations affecting highly conserved residues (Ser185X, Trp215X, Ala26fs, Ala75fs, Met1Ile, and Arg273Cys). GCC allele and genotype distributions showed marked statistically significant differences. (GCC)11 was the most common allele overall; its frequency ranged from 90% in CEPH to 68% in Yoruba and 50% in Chinese and Japanese populations. (GCC)9 was almost as common as (GCC)11 in Chinese and Japanese populations, whereas its frequency was <10% in Yoruba and CEPH populations. The Yoruba population had the highest frequency of the largest alleles [(GCC)12 and (GCC)13], which were almost absent in the other groups. Conclusions: Lack of HLXB9 mutations in some patients and the presence of variable phenotypes suggest DNA alterations in HLXB9 noncoding regions and/or in other genes encoding HLXB9 regulatory molecules or protein partners. If HLXB9, like other homeobox genes, has a threshold beyond which triplet expansions are pathologic, those populations enriched with larger alleles would be at a higher risk. The data illustrate the importance of ethnicity adjustment if these polymorphic markers are to be used in association studies

    Prevalence of atrial fibrillation in different socioeconomic regions of China and its association with stroke: Results from a national stroke screening survey

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    Background: Atrial fibrillation (AF) is the most common sustained arrhythmia in clinical practice. This study aimed to estimate the prevalence of AF in different socioeconomic regions of China and identify its association with stroke, through a national survey. Methods: The study included 726,451 adults aged ≄40 years who were participants of the China National Stroke Screening and Prevention Project, a nationally representative cross-sectional study. Stepwise logistic regression analyses were conducted to investigate the association between AF and stroke. Results: The overall standardized prevalence rate of AF was 2.31%. The prevalence of AF was highest in high-income regions (2.54%), followed by middle-income regions (2.33%), and lowest in low-income regions (1.98%). Women had a higher prevalence of AF than men in all regions (low-income regions, 2.30% vs 1.65%; middle-income regions, 2.78% vs 1.89%; and high-income regions, 2.96% vs 2.12%). Compared with urban residents, the prevalence of AF among rural residents was higher in low- (2.03% vs 1.91%) and middle-income regions (2.69% vs 1.90%), but lower in high-income regions (2.44% vs 2.58%). Participants with AF were more likely to have a stroke than those without AF (9.48% vs 2.26%). After adjusting for age, sex, location, overweight or obese, smoking, drinking, physical inactivity, hypertension, diabetes, dyslipidemia, and a family history of stroke, results showed that AF was significantly associated with stroke. Conclusions: The prevalence of AF has increased in recent years, and it was positively correlated with socioeconomic status, sex (women), location (rural areas), and stroke

    Establishment of porcine and human expanded potential stem cells.

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    We recently derived mouse expanded potential stem cells (EPSCs) from individual blastomeres by inhibiting the critical molecular pathways that predispose their differentiation. EPSCs had enriched molecular signatures of blastomeres and possessed developmental potency for all embryonic and extra-embryonic cell lineages. Here, we report the derivation of porcine EPSCs, which express key pluripotency genes, are genetically stable, permit genome editing, differentiate to derivatives of the three germ layers in chimeras and produce primordial germ cell-like cells in vitro. Under similar conditions, human embryonic stem cells and induced pluripotent stem cells can be converted, or somatic cells directly reprogrammed, to EPSCs that display the molecular and functional attributes reminiscent of porcine EPSCs. Importantly, trophoblast stem-cell-like cells can be generated from both human and porcine EPSCs. Our pathway-inhibition paradigm thus opens an avenue for generating mammalian pluripotent stem cells, and EPSCs present a unique cellular platform for translational research in biotechnology and regenerative medicine
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