2,808 research outputs found
Transformation of \u3cem\u3eTetrahymena thermophila\u3c/em\u3e with Hypermethylated rRNA Genes
The extrachromosomal rRNA genes (rDNA) of Tetrahymena thermophila contain 0.4% N6-methyladenine. C3 strain rDNA was isolated, hypermethylated in vitro, and microinjected into B strain host cells. Clonal cell lines were established, and transformants were selected on the basis of resistance to paromomycin, conferred by the injected rDNA. The effects of methylation by three enzymes which methylate the sequence 5\u27-NAT-3\u27, the dam, EcoRI, and ClaI methylases, were tested. Hypermethylation of the injected rDNA had no effect on transformation efficiency relative to mock-methylated controls. The injected C3 strain rDNA efficiently replaced host rDNA as the major constituent of the population of rDNA molecules. Hypermethylation of the injected DNA was not maintained through 20 to 25 cell generations
Nonfactorizable decay and QCD factorization
We study the unexpectedly large rate for the factorization-forbidden decay
within the QCD factorization approach. We use a non-zero
gluon mass to regularize the infrared divergences in vertex corrections. The
end-point singularities arising from spectator corrections are regularized and
carefully estimated by the off-shellness of quarks. We find that the
contributions arising from the vertex and leading-twist spectator corrections
are numerically small, and the twist-3 spectator contribution with chiral
enhancement and linear end-point singularity becomes dominant. With reasonable
choices for the parameters, the branching ratio for decay is
estimated to be in the range , which is compatible with
the Belle and BaBar data.Comment: Appendix added; it is emphasized that in the dominant twist-3
spectator corrections the end-point singularity contributions may be
estimated by the off-shellness of the charm quark (by the binding energy in
charmonium) and the gluon (by the transverse momentum of the light quark in
the kaon
Observational constraints on noncold dark matter and phenomenological emergent dark energy
It is well known that there are several long-standing problems implying the
discordance of the CDM model. Although most of the models proposed to
resolve these problems assume that dark matter is pressureless, it is still
possible that dark matter is not cold, as current observations have not ruled
out this possibility yet. Therefore, in this article, we treat the dark matter
equation of state parameter as a free parameter, and apply observational data
to investigate the non-coldness of dark matter. Impressing by the simplicity of
the phenomenological emergent dark energy (PEDE) and its ability to relieve the
Hubble tension, we propose the PEDE+ model based on PEDE and
non-cold dark matter. We then place constraints on this model in light of the
Planck 2018 Cosmic Microwave Background (CMB) anisotropies, baryon acoustic
oscillation (BAO) measurements, and the Pantheon compilation of Type Ia
supernovae. The results indicate a preference for a negative dark matter
equation of state parameter at CL for all data sets except CMB alone and
CMB+BAO, which suggests that the non-coldness assumption of dark matter worth
to be investigated further in order to understand the nature of dark matter.
The Hubble tension is alleviated in this scenario compared to the CDM
model, with a significance below 3 level for all data sets except
CMB+Pantheon. However, from the analysis based on Bayesian evidence, we clearly
see that the data sets favor CDM over the PEDE+ model.Comment: 8 pages, 2 figure, published on PR
Wedge Shaped Decompression to Remove Ear Cartilage For a Patient With an Ear intradermal Nevi
Few-Shot Knowledge Graph Completion
Knowledge graphs (KGs) serve as useful resources for various natural language
processing applications. Previous KG completion approaches require a large
number of training instances (i.e., head-tail entity pairs) for every relation.
The real case is that for most of the relations, very few entity pairs are
available. Existing work of one-shot learning limits method generalizability
for few-shot scenarios and does not fully use the supervisory information;
however, few-shot KG completion has not been well studied yet. In this work, we
propose a novel few-shot relation learning model (FSRL) that aims at
discovering facts of new relations with few-shot references. FSRL can
effectively capture knowledge from heterogeneous graph structure, aggregate
representations of few-shot references, and match similar entity pairs of
reference set for every relation. Extensive experiments on two public datasets
demonstrate that FSRL outperforms the state-of-the-art
Comprehensive analysis of industrial-scale heating plants based on different biomass slow pyrolysis technologies:Product property, energy balance, and ecological impact
Slow pyrolysis poly-generation technology for rural heating using agroforest residues has reached the stage of industrial demonstration application in China. Comprehensive assessment of technical characteristics and technical adaptability is essential as further industrialization development requires related plants to be sustainable and replicable. In this study, three typical technical processes and application models are discussed; namely, poly-generation for syngas and char using a rotary kiln (SCRK), poly-generation for syngas and char using a vertical kiln (SCVK), and poly-generation for hot water and char using a chain grate furnace (HCCF). The technical characteristics, adaptability to raw materials, product property, energy balance, and ecological impact were systematically analyzed by an empirical analysis based on industrial-scale project data. The SCRK was advantageous in terms of product quality and yield of char; the low heating value (LHV) of syngas exceeded 17.3 MJ/m3, which was approximately thrice that of the other two technical processes. The energy conversion efficiency of the SCVK was 76.8%, that is, approximately 4.0–5.7 percentage points higher than that of the HCCF and SCRK. The emergy sustainability indices of SCRK, SCVK, and HCCF, as ecological indicators, were 31.2, 21.4, and 24.5, respectively. The above results indicate that the heating plants based on biomass slow pyrolysis have promising application prospects. The technology promotion path was discussed by matching production situations, market demands, and technical characteristics based on a technical evaluation radar chart. Some targeted suggestions were proposed for the industrial application of different biomass slow pyrolysis poly-generation technologies. This study provides a reference for industrialization development of biomass slow pyrolysis technologies for rural heating.</p
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