ガンマ線加熱を受けるクラッド無限板に生ずる非定常熱応力

Transient temperature and thermal stresses distributions arising in an infinite clad slab subjected to internal heat generation decaying exponentially along the thickness due to γ-ray radiation are analyzed with the thermal condition of cooling by convention on both surfaces.Numerical calculations of the transient temperature and thermal stress distributions are carried out for the case of the stainless-carbon-steel clad material. The influence of the absorption coefficient, the Biot number and the clad thickness on the results are cosideredz.無限に広いクラッド厚板が，γ線放射により板厚方向に指数関数状に減衰する内部熱発生によって加熱されるとき，生ずる非定常温度場と非定常熱応力分布を，両表面が熱伝達によって冷却されているという熱的条件のもとに解析した。とくにステンレス―炭素鋼のクラッド材について，非定常温度と非定常熱応力分布の数値計算を行ない，吸収係数やビオ数及びクラッド厚さが結果に及ぼす影響を検討した

La inclusión de las familias inmigrantes en la escuela: el caso de una comunidad peruana en Japón

En las últimas décadas nos encontramos con una aceleración cada vez mayor de las migraciones internacionales, las cuales conllevan a una mayor diversidad dentro de las escuelas. El reto para ellas es no solamente atender a las necesidades y diferencias de los alumnos, sino también incluir a las familias inmigrantes dentro de la escuela y el proceso educativo de sus hijos. El presente artículo estudia el caso de las familias peruanas que han migrado a Japón y que están formando y educando a sus hijos en este país, dentro de una cultura y sociedad tan distinta a la suya. La inclusión de estas familias dentro de la escuela se hace imperante, pues muchas han decidido radicar permanentemente en el Japón. El objetivo del presente trabajo es centrarnos en la relación familia-escuela para analizar de qué manera se están integrando las familias peruanas a la escuela pública japonesa y qué factores estarían influyendo en este proceso de integración. Para ello, el trabajo de campo se realizó en una escuela secundaria en la que la población extranjera es predominantemente peruana, llevando a cabo entrevistas a padres de familia y maestros, así como sesiones de observación participante dentro de la escuela. En el presente artículo, demuestra que más allá de factores prácticos como el idioma y la falta de información; existen otros factores relacionados al capital cultural y la clase social de las familias que estarían influyendo en la relación familia-escuel

Five factors can reconstitute all three phases of microtubule polymerization dynamics

© The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Journal of Cell Biology 215 (2016): 357, doi:10.1083/jcb.201604118.Cytoplasmic microtubules (MTs) undergo growth, shrinkage, and pausing. However, how MT polymerization cycles are produced and spatiotemporally regulated at a molecular level is unclear, as the entire cycle has not been recapitulated in vitro with defined components. In this study, we reconstituted dynamic MT plus end behavior involving all three phases by mixing tubulin with five Drosophila melanogaster proteins (EB1, XMAP215Msps, Sentin, kinesin-13Klp10A, and CLASPMast/Orbit). When singly mixed with tubulin, CLASPMast/Orbit strongly inhibited MT catastrophe and reduced the growth rate. However, in the presence of the other four factors, CLASPMast/Orbit acted as an inducer of pausing. The mitotic kinase Plk1Polo modulated the activity of CLASPMast/Orbit and kinesin-13Klp10A and increased the dynamic instability of MTs, reminiscent of mitotic cells. These results suggest that five conserved proteins constitute the core factors for creating dynamic MTs in cells and that Plk1-dependent phosphorylation is a crucial event for switching from the interphase to mitotic mode.This work was supported by the Grants-in-Aid for Scientific Research (Japan Society for the Promotion of Science KAK ENHI; 15H01317 and 15KT0077).2017-04-3

Drosophila kinesin-8 stabilizes the kinetochore–microtubule interaction

© The Authors, 2019. This article is distributed under the terms of the Creative Commons Attribution-Noncommercial-Share Alike 4.0 International License. The definitive version was published in Journal of Cell Biology 218(2), (2019): 474-488, doi: 10.1083/jcb.201807077.Kinesin-8 is required for proper chromosome alignment in a variety of animal and yeast cell types. However, it is unclear how this motor protein family controls chromosome alignment, as multiple biochemical activities, including inconsistent ones between studies, have been identified. Here, we find that Drosophila kinesin-8 (Klp67A) possesses both microtubule (MT) plus end–stabilizing and –destabilizing activity, in addition to kinesin-8's commonly observed MT plus end–directed motility and tubulin-binding activity in vitro. We further show that Klp67A is required for stable kinetochore–MT attachment during prometaphase in S2 cells. In the absence of Klp67A, abnormally long MTs interact in an “end-on” fashion with kinetochores at normal frequency. However, the interaction is unstable, and MTs frequently become detached. This phenotype is rescued by ectopic expression of the MT plus end–stabilizing factor CLASP, but not by artificial shortening of MTs. We show that human kinesin-8 (KIF18A) is also important to ensure proper MT attachment. Overall, these results suggest that the MT-stabilizing activity of kinesin-8 is critical for stable kinetochore–MT attachment.We thank Kosuke Ariga for helping data analysis, Tomoko Nishiyama for technical support, Tomomi Kiyomitsu for valuable comments on the manuscript, and Elsa Tungadi for proofreading. This work was funded by Japan Society for the Promotion of Science (JSPS) KAK ENHI (15KT0077 and 17H01431) and Laura and Arthur Colwin Endowed Summer Research Fellowship Fund (2015) of the Marine Biological Laboratory to G. Goshima. T. Edzuka is a recipient of a JSPS pre-doctoral fellowship (16J02807)

Simultaneous Measurements of Gas-Solid Flow Rates and Pressure Drop in Downcomer of J-Valve in CFB

To monitor the gas and solid streams in a downcomer of a J-valve in a CFB, the simultaneous measurement technique using the oxygen gas tracer, the hot particle tracer and the pressure drop was developed. By using this novel measurement technique, the dependence of the solid flow on the gas flow in the moving bed in the downcomer of J-valve was investigated. The pressure profile and the pressure balance in the J-valve as well as the CFB were measured. It was clarified that the circulating mass flux in a CFB or solid flow in a J-valve was governed by the pressure drop in the downcomer of the J-valve. The pressure drop in the downcomer of the J-valve was well estimated using the modified Ergun’s equation. To quantitatively control the circulating rate of the solid particles in the CFB, the monitor and tuning of the superficial gas velocity in the downcomer of the J-valve was important

Spontaneous strain due to ferroquadrupolar ordering in UCu2_2Sn

The ternary uranium compound UCu$_2$Sn with a hexagonal ZrPt$_2$Al-type structure shows a phase transition at 16 K. We reported previously that huge lattice-softening is accompanied by the phase transition, which originates from ferroquadrupolar ordering of the ground state non-Kramers doublet $\Gamma_5$. A macroscopic strain, which is expected to emerge spontaneously, was not detected by powder X-ray diffraction in the temperature range between 4.2 and 300 K. To search the spontaneous strain, we have carried out thermal expansion measurements on a single-crystalline sample along the $a$, $b$ and $c$ axes using a capacitance technique with the resolution of $10^{-8}$. In the present experiment, we found the spontaneous $e_{xx} - e_{yy}$ strain which couples to the ground state doublet $\Gamma_5$. The effect of uniaxial pressure along the $a$, $b$ and $c$ axes on the transition temperature is also discussed.Comment: 4 pages, 5 figures, submitted to Phys. Rev.

The roles of microtubule-based motor proteins in mitosis: comprehensive RNAi analysis in the Drosophila S2 cell line

Kinesins and dyneins play important roles during cell division. Using RNA interference (RNAi) to deplete individual (or combinations of) motors followed by immunofluorescence and time-lapse microscopy, we have examined the mitotic functions of cytoplasmic dynein and all 25 kinesins in Drosophila S2 cells. We show that four kinesins are involved in bipolar spindle assembly, four kinesins are involved in metaphase chromosome alignment, dynein plays a role in the metaphase-to-anaphase transition, and one kinesin is needed for cytokinesis. Functional redundancy and alternative pathways for completing mitosis were observed for many single RNAi knockdowns, and failure to complete mitosis was observed for only three kinesins. As an example, inhibition of two microtubule-depolymerizing kinesins initially produced monopolar spindles with abnormally long microtubules, but cells eventually formed bipolar spindles by an acentrosomal pole-focusing mechanism. From our phenotypic data, we construct a model for the distinct roles of molecular motors during mitosis in a single metazoan cell type

Theory for Photon-Assisted Macroscopic Quantum Tunneling in a Stack of Intrinsic Josephson Junctions

We propose a theory for photon-assisted macroscopic quantum tunneling (MQT) in a stack of capacitively-coupled intrinsic Josephson junctions in which the longitudinal Josephson plasma, i.e., longitudinal collective phase oscillation modes, is excited. The scheme of energy-level quantization in the collective oscillatory states is clarified in the $N$-junction system. When the MQT occurs from the single-plasmon states excited by microwave irradiation in the multi-photon process to the uniform voltage state, our theory predicts that the escape rate is proportional to $N^2$. This result is consistent with the recent observation in Bi-2212 intrinsic Josephson junctions.Comment: 5 pages, 2 figure