Numerical simulation of flux jump behavior in REBaCuO ring bulks with an inhomogeneous J c profile during pulsed-field magnetization

Funder: Japan Agency for Medical Research and Development; doi: https://doi.org/10.13039/100009619Abstract: We have investigated the electromagnetic and thermal properties of a REBaCuO ring bulk with an inhomogeneous critical current density, Jc, profile during pulsed field magnetization (PFM) using a numerical simulation and compared those to a bulk with a homogeneous Jc profile. A notch was introduced in the bulk periphery, which was assumed as a crack existing in the actual bulk material. A sudden flux penetration (flux jump) took place through the notch area and as a result, a large temperature rise also took place around this notch. Consequently, the final trapped field profile was simulated to be a ‘C-shaped profile’, which qualitatively reproduced our previous experimental results. The size and position dependences of the notch on the flux penetration behaviour were also simulated, in which a larger and outer notch promotes the flux jump phenomenon easily. On the other hand, in the homogeneous model, under the same conditions, no flux jump phenomenon was observed. These results suggest that the imperfection in the bulk can be a possible starting point of the flux jump. The electromagnetic and thermal hoop stresses were also simulated in the ring bulk during PFM, in which the electromagnetic stress and the thermal stress were both observed to be lower than the fracture strength of the bulk material. This provides good evidence that the experimentally observed ‘C-shaped profile’ results from the flux jump rather than the fracture of the bulk

The Ser176 of T4 endonuclease IV is crucial for the restricted and polarized dC-specific cleavage of single-stranded DNA implicated in restriction of dC-containing DNA in host Escherichia coli

Endonuclease (Endo) IV encoded by denB of bacteriophage T4 is an enzyme that cleaves single-stranded (ss) DNA in a dC-specific manner. Also the growth of dC-substituted T4 phage and host Escherichia coli cells is inhibited by denB expression presumably because of the inhibitory effect on replication of dC-containing DNA. Recently, we have demonstrated that an efficient cleavage by Endo IV occurs exclusively at the 5′-proximal dC (dC1) within a hexameric or an extended sequence consisting of dC residues at the 5′-proximal and the 3′-proximal positions (dCs tract), in which a third dC residue within the tract affects the polarized cleavage and cleavage rate. Here we isolate and characterize two denB mutants, denB(W88R) and denB(S176N). Both mutant alleles have lost the detrimental effect on the host cell. Endo IV(W88R) shows no enzymatic activity (<0.4% of that of wild-type Endo IV). On the other hand, Endo IV(S176N) retains cleavage activity (17.5% of that of wild-type Endo IV), but has lost the polarized and restricted cleavage of a dCs tract, indicating that the Ser176 residue of Endo IV is implicated in the polarized cleavage of a dCs tract which brings about a detrimental effect on the replication of dC-containing DNA

knn-seq: Efficient, Extensible kNN-MT Framework

k-nearest-neighbor machine translation (kNN-MT) boosts the translation quality of a pre-trained neural machine translation (NMT) model by utilizing translation examples during decoding. Translation examples are stored in a vector database, called a datastore, which contains one entry for each target token from the parallel data it is made from. Due to its size, it is computationally expensive both to construct and to retrieve examples from the datastore. In this paper, we present an efficient and extensible kNN-MT framework, knn-seq, for researchers and developers that is carefully designed to run efficiently, even with a billion-scale large datastore. knn-seq is developed as a plug-in on fairseq and easy to switch models and kNN indexes. Experimental results show that our implemented kNN-MT achieves a comparable gain to the original kNN-MT, and the billion-scale datastore construction took 2.21 hours in the WMT'19 German-to-English translation task. We publish our knn-seq as an MIT-licensed open-source project and the code is available on https://github.com/naist-nlp/knn-seq . The demo video is available on https://youtu.be/zTDzEOq80m0

A New Technique for Improving Visualization of Mucosal Lesions During Endoscopic Photodynamic Therapy

A new device consisting of a conventional fiberscope and a new TV system (model OTV-S5, Olympus Optical Co., Tokyo, Japan) has been developed to achieve accurate irradiation of laser light in photodynamic therapy for gastric cancer. This model has high resolution and sensitivity, and its signal can be transmitted by red, green and blue. In front of the CCD we inserted a special interference filter which has specific absorption of red light with 2.3% transmissivity at a 630 nm wavelength and a 50 nm absorption band of full width at half maximum. The average transmittance in the visible region, except for at 630 nm, was 90%. A neutral density filter with 16% transmittance was added to adjust to the sensitivity of the CCD. The device makes it possible to perform accurate irradiation, because we can observe both the lesion and the laser spot on a monitor in original colors during irradiation

Characterization of highly efficient heavy-ion mutagenesis in Arabidopsis thaliana

<p>Abstract</p> <p>Background</p> <p>Heavy-ion mutagenesis is recognised as a powerful technology to generate new mutants, especially in higher plants. Heavy-ion beams show high linear energy transfer (LET) and thus more effectively induce DNA double-strand breaks than other mutagenic techniques. Previously, we determined the most effective heavy-ion LET (LET_max: 30.0 keV μm^-1) for <it>Arabidopsis </it>mutagenesis by analysing the effect of LET on mutation induction. However, the molecular structure of mutated DNA induced by heavy ions with LET_maxremains unclear. Knowledge of the structure of mutated DNA will contribute to the effective exploitation of heavy-ion beam mutagenesis.</p> <p>Results</p> <p>Dry <it>Arabidopsis thaliana </it>seeds were irradiated with carbon (C) ions with LET_maxat a dose of 400 Gy and with LET of 22.5 keV μm^-1at doses of 250 Gy or 450 Gy. The effects on mutation frequency and alteration of DNA structure were compared. To characterise the structure of mutated DNA, we screened the well-characterised mutants <it>elongated hypocotyls </it>(<it>hy</it>) and <it>glabrous </it>(<it>gl</it>) and identified mutated DNA among the resulting mutants by high-resolution melting curve, PCR and sequencing analyses. The mutation frequency induced by C ions with LET_maxwas two-fold higher than that with 22.5 keV μm^-1and similar to the mutation frequency previously induced by ethyl methane sulfonate. We identified the structure of 22 mutated DNAs. Over 80% of the mutations caused by C ions with both LETs were base substitutions or deletions/insertions of less than 100 bp. The other mutations involved large rearrangements.</p> <p>Conclusions</p> <p>The C ions with LET_maxshowed high mutation efficiency and predominantly induced base substitutions or small deletions/insertions, most of which were null mutations. These small alterations can be determined by single-nucleotide polymorphism (SNP) detection systems. Therefore, C ions with LET_maxmight be useful as a highly efficient reverse genetic system in conjunction with SNP detection systems, and will be beneficial for forward genetics and plant breeding.</p