2,409 research outputs found
Tetrahedral and Triangular Deformations of Nuclei in Mass Region
We study static non-axial octupole deformations in proton-rich nuclei,
Ge, Se, Kr, Sr, Zr and Mo, by using
the Skyrme Hartree-Fock plus BCS calculation with no restrictions on the
nuclear shape. The calculation predicts that the oblate ground state in
Se is extremely soft for the triangular deformation, and that
in Zr the low-lying local minimum state coexisting with the prolate
ground state has the tetrahedral deformation.Comment: 8 pages, 4 Postscript figures, REVTE
Dinoflagellate Phylogeny as Inferred from Heat Shock Protein 90 and Ribosomal Gene Sequences
Interrelationships among dinoflagellates in molecular phylogenies are largely unresolved, especially in the deepest branches. Ribosomal DNA (rDNA) sequences provide phylogenetic signals only at the tips of the dinoflagellate tree. Two reasons for the poor resolution of deep dinoflagellate relationships using rDNA sequences are (1) most sites are relatively conserved and (2) there are different evolutionary rates among sites in different lineages. Therefore, alternative molecular markers are required to address the deeper phylogenetic relationships among dinoflagellates. Preliminary evidence indicates that the heat shock protein 90 gene (Hsp90) will provide an informative marker, mainly because this gene is relatively long and appears to have relatively uniform rates of evolution in different lineages.We more than doubled the previous dataset of Hsp90 sequences from dinoflagellates by generating additional sequences from 17 different species, representing seven different orders. In order to concatenate the Hsp90 data with rDNA sequences, we supplemented the Hsp90 sequences with three new SSU rDNA sequences and five new LSU rDNA sequences. The new Hsp90 sequences were generated, in part, from four additional heterotrophic dinoflagellates and the type species for six different genera. Molecular phylogenetic analyses resulted in a paraphyletic assemblage near the base of the dinoflagellate tree consisting of only athecate species. However, Noctiluca was never part of this assemblage and branched in a position that was nested within other lineages of dinokaryotes. The phylogenetic trees inferred from Hsp90 sequences were consistent with trees inferred from rDNA sequences in that the backbone of the dinoflagellate clade was largely unresolved.The sequence conservation in both Hsp90 and rDNA sequences and the poor resolution of the deepest nodes suggests that dinoflagellates reflect an explosive radiation in morphological diversity in their recent evolutionary past. Nonetheless, the more comprehensive analysis of Hsp90 sequences enabled us to infer phylogenetic interrelationships of dinoflagellates more rigorously. For instance, the phylogenetic position of Noctiluca, which possesses several unusual features, was incongruent with previous phylogenetic studies. Therefore, the generation of additional dinoflagellate Hsp90 sequences is expected to refine the stem group of athecate species observed here and contribute to future multi-gene analyses of dinoflagellate interrelationships
Chief Justice Greene on Mob Law
On January 18, 1882, three men were hung by a mob in Seattle on what is now James Street between First and Second Avenues. Two of them had just been held for trial after a hearing before a justice of the peace for the murder the evening before of a popular Seattle citizen. They were seized by a mob in the court room and hurried to the place of execution, the sheriff and his deputies present being overpowered. The third was in jail awaiting trial for the murder of a policeman and was taken from the jail on the same day after the death of the first two, the jail doors being broken down by the mob. Prominent citizens of the city were members of the mob. At the April term following the lynching, a grand jury was called and Judge Greene gave to it the charge hereinafter set forth. No indictment was found by the grand jury. Probably there has been no case of like character in the nation in which members of such a vigilance committee have been punished. But, published in full in the press some three months after the mob executions, Judge Greene\u27s charge must have had a sobering and helpful effect upon the citizens of Seattle, and in large measure counteracted the educational evils of the tragedy. There may have been more inspiring words written of the sacredness of our constitutional rights and the value and obligations of citizenship in this, our country, but if so, they have not come to my attention
Performance of Seedigated and Conventionally Planted Crops
Seedigation is the use of a moving sprinkler irrigation system to broadcast seeds on the soil surface. Seed germination, plant characteristics and yield for grain sorghum, winter wheat and soybeans that were seedigated and conventionally planted are compared. When the seeding rates for seedigation were increased above that for conventional planting, and adequate moisture was available for germination, grain sorghum and wheat seedigated on tilled surfaces produced yields similar to conventionally planted crops. Seedigation of soybeans into fallow conditions, or when used as a relay crop, was unsuccessful. Shallow disking following seedigation did not improve germination or yield of grain sorghum or winter wheat. Using seedigation to plant wheat into soybeans offers good potential. Seedigating wheat into dense grain sorghum canopies was less successful
Performance of Seedigated and Conventionally Planted Crops
Seedigation is the use of a moving sprinkler irrigation system to broadcast seeds on the soil surface. Seed germination, plant characteristics and yield for grain sorghum, winter wheat and soybeans that were seedigated and conventionally planted are compared. When the seeding rates for seedigation were increased above that for conventional planting, and adequate moisture was available for germination, grain sorghum and wheat seedigated on tilled surfaces produced yields similar to conventionally planted crops. Seedigation of soybeans into fallow conditions, or when used as a relay crop, was unsuccessful. Shallow disking following seedigation did not improve germination or yield of grain sorghum or winter wheat. Using seedigation to plant wheat into soybeans offers good potential. Seedigating wheat into dense grain sorghum canopies was less successful
Collective T- and P- Odd Electromagnetic Moments in Nuclei with Octupole Deformations
Parity and time invariance violating forces produce collective P- and T- odd
moments in nuclei with static octupole deformation. Collective Schiff moment,
electric octupole and dipole and also magnetic quadrupole appear due to the
mixing of rotational levels of opposite parity and can exceed single-particle
moments by more than a factor of 100. This enhancement is due to two factors,
the collective nature of the intrinsic moments and the small energy separation
between members of parity doublets. The above moments induce T- and P- odd
effects in atoms and molecules. Experiments with such systems may improve
substantially the limits on time reversal violation.Comment: 9 pages, Revte
Enhanced T-odd P-odd Electromagnetic Moments in Reflection Asymmetric Nuclei
Collective P- and T- odd moments produced by parity and time invariance
violating forces in reflection asymmetric nuclei are considered. The enhanced
collective Schiff, electric dipole and octupole moments appear due to the
mixing of rotational levels of opposite parity. These moments can exceed
single-particle moments by more than two orders of magnitude. The enhancement
is due to the collective nature of the intrinsic moments and the small energy
separation between members of parity doublets. In turn these nuclear moments
induce enhanced T- and P- odd effects in atoms and molecules. First a simple
estimate is given and then a detailed theoretical treatment of the collective
T-, P- odd electric moments in reflection asymmetric, odd-mass nuclei is
presented and various corrections evaluated. Calculations are performed for
octupole deformed long-lived odd-mass isotopes of Rn, Fr, Ra, Ac and Pa and the
corresponding atoms. Experiments with such atoms may improve substantially the
limits on time reversal violation.Comment: 28 pages, Revte
Structure and mechanism of the RNA dependent RNase Cas13a from Rhodobacter capsulatus
Cas13a are single-molecule effectors of the Class II, Type VI family of CRISPR-Cas systems that are part of the bacterial and archaeal defense systems. These RNA-guided and RNA-activated RNA endonucleases are characterized by their ability to cleave target RNAs complementary to the crRNA-spacer sequence, as well as bystander RNAs in a sequence-unspecific manner. Due to cleavage of cellular transcripts they induce dormancy in the host cell and thus protect the bacterial population by aborting the infectious cycle of RNA-phages. Here we report the structural and functional characterization of a Cas13a enzyme from the photo-auxotrophic purple bacteria Rhodobacter capsulatus. The X-ray crystal structure of the RcCas13a-crRNA complex reveals its distinct crRNA recognition mode as well as the enzyme in its contracted, pre-activation conformation. Using site-directed mutagenesis in combination with mass spectrometry, we identified key residues responsible for pre-crRNA processing by RcCas13a in its distinct catalytic site, and elucidated the acid-base mediated cleavage reaction mechanism. In addition, RcCas13a cleaves target-RNA as well as bystander-RNAs in Escherichia coli which requires its catalytic active HEPN (higher eukaryotes and prokaryotes nucleotide binding) domain nuclease activity. Our data provide further insights into the molecular mechanisms and function of this intriguing family of RNA-dependent RNA endonucleases that are already employed as efficient tools for RNA detection and regulation of gene expression
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