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Moiré-pattern interlayer potentials in van der Waals materials in the random-phase approximation
Leconte, Nicolas,Jung, Jeil,Lebè,gue, Sé,bastien,Gould, Tim American Physical Society 2017 Physical review. B Vol.96 No.19
<P>Stacking-dependent interlayer interactions are important for understanding the structural and electronic properties in incommensurable two-dimensional material assemblies where long-range moire patterns arise due to small lattice constant mismatch or twist angles. Here we study the stacking-dependent interlayer coupling energies between graphene (G) and hexagonal boron nitride (BN) homo-and heterostructures using high-level random-phase approximation (RPA) ab initio calculations. Our results show that although total binding energies within LDA and RPA differ substantially by a factor of 200%-400%, the energy differences as a function of stacking configuration yield nearly constant values with variations smaller than 20%, meaning that LDAestimates are quite reliable. We produce phenomenological fits to these energy differences, which allows us to calculate various properties of interest including interlayer spacing, sliding energetics, pressure gradients, and elastic coefficients to high accuracy. The importance of long-range interactions (captured by RPA but not LDA) on various properties is also discussed. Parametrizations for all fits are provided.</P>
Gulati, Reema,Komuravelly, Arpitha,Leb, Stephen,Mhanna, Maroun J,Ghori, Abdullah,Leon, Janeen,Needlman, Robert The Korean Society of Pediatric Gastroenterology 2018 Pediatric gastroenterology, hepatology & nutrition Vol.21 No.2
Purpose: Rome criteria are considered the gold standard for diagnosing functional constipation. The modified Bristol stool form scale (m-BSFS) was validated to measure stool form in children. However, neither the potential use of the m-BSFS as a tool to facilitate the diagnosis of potential constipation, nor the agreement between m-BSFS and stool consistency by Rome has been studied. Our objective is to determine if m-BSFS is a reliable tool to facilitate detection of constipation; and the agreement between stool form by m-BSFS and hard stool criteria in Rome. Methods: A survey tool with the Rome III criteria and the m-BSFS was developed. A Likert-scale addressed frequency of each stool form on the m-BSFS. Responses to Rome III and m-BSFS were compared. Results: The sensitivity and specificity of the m-BSFS was 79.2% and 66.0% respectively; and in children <4 years. improved to 81.2% and 75.0% respectively. There was poor agreement between hard stools by m-BSFS and the painful or hard bowel movement question of Rome Criteria. Conclusion: The potential utility of m-BSFS as a reasonably good tool to facilitate the diagnosis of potential constipation in children is shown. The poor agreement between painful or hard stool question in Rome III, and ratings for hard stool on the m-BSFS illustrates that one's perception may differ between a question and a picture. A useful pictorial tool to appraise stool form may, thus, be a favorable complement in the process of enquiry about bowel habits in well-child care.
Reema Gulati,Arpitha Komuravelly,Stephen Leb,Maroun J Mhanna,Abdullah Ghori,Janeen Leon,Robert Needlman 대한소아소화기영양학회 2018 Pediatric gastroenterology, hepatology & nutrition Vol.21 No.2
Purpose: Rome criteria are considered the gold standard for diagnosing functional constipation. The modified Bristol stool form scale (m-BSFS) was validated to measure stool form in children. However, neither the potential use of the m-BSFS as a tool to facilitate the diagnosis of potential constipation, nor the agreement between m-BSFS and stool consistency by Rome has been studied. Our objective is to determine if m-BSFS is a reliable tool to facilitate detection of constipation; and the agreement between stool form by m-BSFS and hard stool criteria in Rome. Methods: A survey tool with the Rome III criteria and the m-BSFS was developed. A Likert-scale addressed frequency of each stool form on the m-BSFS. Responses to Rome III and m-BSFS were compared. Results: The sensitivity and specificity of the m-BSFS was 79.2% and 66.0% respectively; and in children <4 years. improved to 81.2% and 75.0% respectively. There was poor agreement between hard stools by m-BSFS and the painful or hard bowel movement question of Rome Criteria. Conclusion: The potential utility of m-BSFS as a reasonably good tool to facilitate the diagnosis of potential constipation in children is shown. The poor agreement between painful or hard stool question in Rome III, and ratings for hard stool on the m-BSFS illustrates that one’s perception may differ between a question and a picture. A useful pictorial tool to appraise stool form may, thus, be a favorable complement in the process of enquiry about bowel habits in well-child care.
First-principles investigation of two-dimensional trichalcogenide and sesquichalcogenide monolayers
Debbichi, L.,Kim, H.,Bjö,rkman, T.,Eriksson, O.,Lebè,gue, S. American Physical Society 2016 Physical Review B Vol.93 No.24
<P>We have used density functional theory to investigate the dynamical stability and the electronic structure of several new semiconducting two-dimensional single layers, with chemical compositions such as ABX(3) and A(2)X(3). The calculated interlayer binding energies and the absence of imaginary states in the phonon spectra indicate the possibility to isolate them in the form of a single layer. Also, the calculated band edges reveal that some of these two-dimensional materials are promising candidates for water-splitting applications.</P>