3,397 research outputs found
2-(Furan-2-yl)-5-(2-nitrobenzyl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one
The title compound, C20H16N2O4S, was prepared by introduction of a 2-nitrobenzyl group to 2-(furan-2-yl)-2,3-dihydro-1,5-benzothiazepin-4(5H)-one via an alkaline-catalysed reaction. The thiazepine ring adopts a twist-boat conformation. The furan ring is oriented at dihedral angles of 56.75 (14) and 10.82 (14)° with respect to the two benzene rings, while the two benzene rings make a dihedral angle of 62.96 (10)°. Weak intermolecular C—H⋯O hydrogen bonds occur in the crystal structure
Light-cone Sum Rule Analysis of Semileptonic Decays
In this work, we analyze the semileptonic decay processes of in the light-cone sum rule approach. In the calculation of the form
factors of baryon transition matrix element, the light-cone
distribution amplitudes of which are obtained from QCD sum rule in
the heavy quark effective field theory framework are used. With the calculation
of the six form factors of transition matrix element,
the differential decay widths of and absolute branching fractions are
obtained. Additionally the ratio of is
obtained. These results are in accordance with the newest experimental result
and other theoretical calculations and predictions.Comment: 10 pages,6 figure
Bayesian System Identification based on Hierarchical Sparse Bayesian Learning and Gibbs Sampling with Application to Structural Damage Assessment
The focus in this paper is Bayesian system identification based on noisy
incomplete modal data where we can impose spatially-sparse stiffness changes
when updating a structural model. To this end, based on a similar hierarchical
sparse Bayesian learning model from our previous work, we propose two Gibbs
sampling algorithms. The algorithms differ in their strategies to deal with the
posterior uncertainty of the equation-error precision parameter, but both
sample from the conditional posterior probability density functions (PDFs) for
the structural stiffness parameters and system modal parameters. The effective
dimension for the Gibbs sampling is low because iterative sampling is done from
only three conditional posterior PDFs that correspond to three parameter
groups, along with sampling of the equation-error precision parameter from
another conditional posterior PDF in one of the algorithms where it is not
integrated out as a "nuisance" parameter. A nice feature from a computational
perspective is that it is not necessary to solve a nonlinear eigenvalue problem
of a structural model. The effectiveness and robustness of the proposed
algorithms are illustrated by applying them to the IASE-ASCE Phase II simulated
and experimental benchmark studies. The goal is to use incomplete modal data
identified before and after possible damage to detect and assess
spatially-sparse stiffness reductions induced by any damage. Our past and
current focus on meeting challenges arising from Bayesian inference of
structural stiffness serve to strengthen the capability of vibration-based
structural system identification but our methods also have much broader
applicability for inverse problems in science and technology where system
matrices are to be inferred from noisy partial information about their
eigenquantities.Comment: 12 figure
Establishment of persistent infection with foot-and-mouth disease virus in BHK-21 cells
<p>Abstract</p> <p>Background</p> <p>Foot-and-mouth disease virus (FMDV) is able to cause persistent infection in ruminants besides acute infection and disease. Since the mechanisms of viral persistence and the determining factors are still unknown, <it>in vitro </it>systems help explore and reveal mechanisms of persistence <it>in vivo </it>by providing useful models for the study of RNA genome mutations and evolution. Ammonium chloride, a lysosomotropic agent that raises intralysosomal pH, reduces the yield of FMDV during infection of BHK-21 cells.</p> <p>Results</p> <p>The persistent infection with FMDV serotype O in BHK-21 cells was selected and established readily after treatment of ammonium chloride that acts primarily on the cells. Intact virions were observed located inside the endosomes. Viral genome RNAs and specific proteins were detected in the persistent cells to validate the establishment of viral persistence. Infection of the persistent viruses could not form plaques in host cells but virulence was enhanced. Basing on analysis and comparison of cDNA sequences of resident viruses and wild type viruses, 15 amine acid mutations were found, all of which were located in nonstructural proteins rather than in structural proteins.</p> <p>Conclusions</p> <p>Therefore, persistent infection of cell cultures with FMDV is successfully established with some distinctive features. It would be worthwhile to further investigate the mechanisms of viral persistence.</p
Radio Polarization of BL Lacertae objects
In this paper, using the database of the university of Michigan Radio
Astronomy Observatory (UMRAO) at three (4.8 GHz, 8 GHZ, and 14.5 GHz) radio
frequencies, we studied the polarization properties for 47 BL Lacertae
objects(38 radio selected BL Lacertae objects, 7 X-ray selected BL Lacertae,
and two inter-middle objects (Mkn 421 and Mkn 501), and found that (1) The
polarizations at higher radio frequency is higher than those at lower
frequency, (2) The variability of polarization at higher radio frequency is
higher than those at lower frequency, (3) The polarization is correlated with
the radio spectral index, and (4) The polarization is correlated with
core-dominance parameter for those objects with known core-dominance parameters
suggesting that the relativistic beaming could explain the polarization
characteristic of BL Lacs.Comment: 5 pages, 3 figures, 1 table. PASJ, in pres
MicroRNA-23a promotes myelination in the central nervous system.
Demyelinating disorders including leukodystrophies are devastating conditions that are still in need of better understanding, and both oligodendrocyte differentiation and myelin synthesis pathways are potential avenues for developing treatment. Overexpression of lamin B1 leads to leukodystrophy characterized by demyelination of the central nervous system, and microRNA-23 (miR-23) was found to suppress lamin B1 and enhance oligodendrocyte differentiation in vitro. Here, we demonstrated that miR-23a-overexpressing mice have increased myelin thickness, providing in vivo evidence that miR-23a enhances both oligodendrocyte differentiation and myelin synthesis. Using this mouse model, we explored possible miR-23a targets and revealed that the phosphatase and tensin homologue/phosphatidylinositol trisphosphate kinase/Akt/mammalian target of rapamycin pathway is modulated by miR-23a. Additionally, a long noncoding RNA, 2700046G09Rik, was identified as a miR-23a target and modulates phosphatase and tensin homologue itself in a miR-23a-dependent manner. The data presented here imply a unique role for miR-23a in the coordination of proteins and noncoding RNAs in generating and maintaining healthy myelin
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