3,133 research outputs found

    Diffractive parton distributions from the saturation model

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    We review diffractive deep inelastic scattering (DIS) in the light of the collinear factorization theorem. This theorem allows to define diffractive parton distributions in the leading twist approach. Due to its selective final states, diffractive DIS offers interesting insight into the form of the diffractive parton distributions which we explore with the help of the saturation model. We find Regge-like factorization with the correct energy dependence measured at HERA. A remarkable feature of diffractive DIS is the dominance of the twist-4 contribution for small diffractive masses. We quantify this effect and make a comparison with the data.Comment: 18 pages, 6 figures, latex, Q_0^2 corrected in comparison to the journal versio

    Flow Friction or Spontaneous Ignition?

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    "Flow friction," a proposed ignition mechanism in oxygen systems, has proved elusive in attempts at experimental verification. In this paper, the literature regarding flow friction is reviewed and the experimental verification attempts are briefly discussed. Another ignition mechanism, a form of spontaneous combustion, is proposed as an explanation for at least some of the fire events that have been attributed to flow friction in the literature. In addition, the results of a failure analysis performed at NASA Johnson Space Center White Sands Test Facility are presented, and the observations indicate that spontaneous combustion was the most likely cause of the fire in this 2000 psig (14 MPa) oxygen-enriched system

    Smoking behaviour, involuntary smoking, attitudes towards smoke-free legislations, and tobacco control activities in the European Union

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    The six most important cost-effective policies on tobacco control can be measured by the Tobacco Control Scale (TCS). The objective of our study was to describe the correlation between the TCS and smoking prevalence, self-reported exposure to secondhand smoke (SHS) and attitudes towards smoking restrictions in the 27 countries of the European Union (EU27)

    Burning of CP Titanium (Grade 2) in Oxygen-Enriched Atmospheres

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    The flammability in oxygen-enriched atmospheres of commercially pure (CP) titanium rods as a function of diameter and test gas pressure was determined. Test samples of varying diameters were ignited at the bottom and burned upward in 70% O2/balance N2 and in 99.5+% O2 at various pressures. The burning rate of each ignited sample was determined by observing the apparent regression rate of the melting interface (RRMI) of the burning samples. The burning rate or RRMI increased with decreasing test sample diameter and with increasing test gas pressure and oxygen concentratio

    Reasons for tubal sterilisation, regret and depressive symptoms

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    Objective—To examine the associations between sterilisation reasons, regret, and depressive symptoms. Study Design—Black, Hispanic, and non-Hispanic White US women ages 25–45 who participated in the National Survey of Fertility Barriers (NSFB) and reported a tubal sterilisation surgery were included in the sample for this study (n=837). Logistic regression was used to examine how characteristics of the sterilisation surgery (reasons for sterilisation, time since sterilisation, and new relationship since sterilisation) are associated with the odds of sterilisation regret, and linear regression was used to examine associations between sterilisation regret, sociodemographic factors, and depressive symptoms. Results—Findings revealed that 28 percent of U.S. women who have undergone tubal sterilisation report regret. Time since sterilisation and having a reason for sterilisation other than simply not wanting (more) children (e.g., situational factors, health problems, encouragement by others, and other reasons) are associated with significantly higher odds of sterilisation regret. Finally, sterilisation regret is significantly associated with depressive symptoms after controlling for sociodemographic characteristics. Conclusion—Sterilisation regret is relatively common among women who have undergone tubal sterilisation, and regret is linked to elevated, but not necessarily clinical depressive symptoms. The reasons for sterilisation can have important implications for women’s sterilisation regret and associated depressive symptoms

    2 Novel deletions of the sterol 27-hydroxylase gene in a Chinese Family with Cerebrotendinous Xanthomatosis

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    <p>Abstract</p> <p>Background</p> <p>Cerebrotendinous xanthomatosis (CTX) is a rare lipid-storage disease. We investigated the clinic manifestation, histopathology and sterol 27-hydroxylase gene (CYP27A1) in a Chinese family with Cerebrotendinous Xanthomatosis (CTX).</p> <p>Case Presentation</p> <p>A 36-year-old female with typical CTX clinical manifestation had Spindle-shaped lipid crystal clefts in xanthomas and "onion-like demyelination" in sural nerve. The patient was compound heterozygote carrying two deletions in exon 1 (c.73delG) and exon 2 (c.369_375delGTACCCA). The family memebers were carriers.</p> <p>Conclusions</p> <p>A Chinese family with Cerebrotendinous Xanthomatosis had typical clinical manifestation. CYP27A1 mutations were found in the proband and all other family members.</p

    Aspirin and the risk of colorectal and other digestive tract cancers: an&#160;updated meta-analysis through 2019

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    Aspirin has been associated with a reduced risk of colorectal cancer, and possibly of a few other digestive tract cancers. The quantification of risk reduction and the optimal dose and duration of aspirin use for the prevention of colorectal and other digestive tract cancers remains unclear

    Reasons for tubal sterilisation, regret and depressive symptoms

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    Objective—To examine the associations between sterilisation reasons, regret, and depressive symptoms. Study Design—Black, Hispanic, and non-Hispanic White US women ages 25–45 who participated in the National Survey of Fertility Barriers (NSFB) and reported a tubal sterilisation surgery were included in the sample for this study (n=837). Logistic regression was used to examine how characteristics of the sterilisation surgery (reasons for sterilisation, time since sterilisation, and new relationship since sterilisation) are associated with the odds of sterilisation regret, and linear regression was used to examine associations between sterilisation regret, sociodemographic factors, and depressive symptoms. Results—Findings revealed that 28 percent of U.S. women who have undergone tubal sterilisation report regret. Time since sterilisation and having a reason for sterilisation other than simply not wanting (more) children (e.g., situational factors, health problems, encouragement by others, and other reasons) are associated with significantly higher odds of sterilisation regret. Finally, sterilisation regret is significantly associated with depressive symptoms after controlling for sociodemographic characteristics. Conclusion—Sterilisation regret is relatively common among women who have undergone tubal sterilisation, and regret is linked to elevated, but not necessarily clinical depressive symptoms. The reasons for sterilisation can have important implications for women’s sterilisation regret and associated depressive symptoms

    Surface Display of Complex Enzymes by in Situ SpyCatcher-SpyTag Interaction

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    The display of complex proteins on the surface of cells is of great importance for protein engineering and other fields of biotechnology. Herein, we describe a modular approach, in which the membrane anchor protein Lpp-OmpA and a protein of interest (passenger) are expressed independently as genetically fused SpyCatcher and SpyTag units and assembled in situ by post-translational coupling. Using fluorescent proteins, we first demonstrate that this strategy allows the construct to be installed on the surface of E. coli cells. The scope of our approach was then demonstrated by using three different functional enzymes, the stereoselective ketoreductase Gre2p, the homotetrameric glucose 1-dehydrogenase GDH, and the bulky heme- and diflavin-containing cytochrome P450 BM3 (BM3). In all cases, the SpyCatcher-SpyTag method enabled the generation of functional whole-cell biocatalysts, even for the bulky BM3, which could not be displayed by conventional fusion with Lpp-OmpA. Furthermore, by using a GDH variant carrying an internal SpyTag, the system could be used to display an enzyme with unmodified N- and C-termini
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