6,606 research outputs found
Review of the Genus Andropogon (Poaceae: Andropogoneae) in America Based on Cytogenetic Studies
Andropogon is a pantropical grass genus comprising 100–120 species and found mainly in the grasslands of Africa and the Americas. In the new world the genus is represented by approximately sixty (diploids or hexaploids) species grouped in three sections. The hexaploid condition occurs only in the Americas and the full process of this origin is still uncertain, although cytogenetic analysis coupled with taxonomic evidence have provided strong support for new hypothesis. Stebbins proposed the first hypothesis suggesting that the origin of polyploidy in species of Andropogon in North America resulted from duplication of the genome of some diploid species, and then by intergeneric crosses with species of a related genus. Since then, numerous studies were performed to clarify the evolutionary history of the genus in America. In this paper, we present a review of cytogenetic studies in the American Andropogon species during the last four decades.Fil: Nagahama, Nicolas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Norrmann, Guillermo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Botanica del Nordeste. Universidad Nacional del Nordeste. Facultad de Ciencias Agrarias. Instituto de Botanica del Nordeste; Argentin
Clostridium perfringensepsilon toxin H149A mutant as a platform for receptor binding studies
Clostridium perfringens epsilon toxin (Etx) is a pore-forming toxin responsible for a severe and rapidly fatal enterotoxemia of ruminants. The toxin is classified as a category B bioterrorism agent by the U.S. Government Centres for Disease Control and Prevention (CDC), making work with recombinant toxin difficult. To reduce the hazard posed by work with recombinant Etx, we have used a variant of Etx that contains a H149A mutation (Etx-H149A), previously reported to have reduced, but not abolished, toxicity. The three-dimensional structure of H149A prototoxin shows that the H149A mutation in domain III does not affect organisation of the putative receptor binding loops in domain I of the toxin. Surface exposed tyrosine residues in domain I of Etx-H149A (Y16, Y20, Y29, Y30, Y36 and Y196) were mutated to alanine and mutants Y30A and Y196A showed significantly reduced binding to MDCK.2 cells relative to Etx-H149A that correlated with their reduced cytotoxic activity. Thus, our study confirms the role of surface exposed tyrosine residues in domain I of Etx in binding to MDCK cells and the suitability of Etx-H149A for further receptor binding studies. In contrast, binding of all of the tyrosine mutants to ACHN cells was similar to that of Etx-H149A, suggesting that Etx can recognise different cell surface receptors. In support of this, the crystal structure of Etx-H149A identified a glycan (β-octyl-glucoside) binding site in domain III of Etx-H149A, which may be a second receptor binding site. These findings have important implications for developing strategies designed to neutralise toxin activity
Studies on secretion and proteolytic processing of prorenins
Thesis (Ph.D.)--University of Tsukuba, (A), no. 930, 1991.12.3
The Development of Values Education Under the Integrated Learning Subject in the Philippines: Islamic Concepts and Peace Building
This research on the Philippine values education clarifies how much their understandings on values have been diversified, especially between Christians and Muslims
Magnetic properties of epitaxial FeO films with various crystal orientations and TMR effect in room temperature
FeO is a ferrimagnetic spinel ferrite that exhibits electric
conductivity at room temperature (RT). Although the material has been predicted
to be a half metal according to ab-initio calculations, magnetic tunnel
junctions (MTJs) with FeO electrodes have demonstrated a small tunnel
magnetoresistance effect. Not even the sign of the TMR ratio has been
experimentally established. Here, we report on the magnetic properties of
epitaxial FeO films with various crystal orientations. The films
exhibited apparent crystal orientation dependence on hysteresis curves. In
particular, FeO(110) films exhibited in-plane uniaxial magnetic
anisotropy. With respect to the squareness of hysteresis, FeO (111)
demonstrated the largest squareness. Furthermore, we fabricated MTJs with
FeO(110) electrodes, and obtained an TMR effect of -12\% at RT. The
negative TMR ratio corresponded to the negative spin polarization of
FeO predicted from band calculations
Computational ghost imaging using deep learning
Computational ghost imaging (CGI) is a single-pixel imaging technique that
exploits the correlation between known random patterns and the measured
intensity of light transmitted (or reflected) by an object. Although CGI can
obtain two- or three- dimensional images with a single or a few bucket
detectors, the quality of the reconstructed images is reduced by noise due to
the reconstruction of images from random patterns. In this study, we improve
the quality of CGI images using deep learning. A deep neural network is used to
automatically learn the features of noise-contaminated CGI images. After
training, the network is able to predict low-noise images from new
noise-contaminated CGI images
Random phase-free kinoform for large objects
We propose a random phase-free kinoform for large objects. When not using the
random phase in kinoform calculation, the reconstructed images from the
kinoform are heavy degraded, like edge-only preserved images. In addition, the
kinoform cannot record an entire object that exceeds the kinoform size because
the object light does not widely spread. In order to avoid this degradation and
to widely spread the object light, the random phase is applied to the kinoform
calculation; however, the reconstructed image is contaminated by speckle noise.
In this paper, we overcome this problem by using our random phase-free method
and error diffusion method
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