2,902 research outputs found
Strong valence fluctuation in the quantum critical heavy fermion superconductor beta-YbAlB4: A hard x-ray photoemission study
Electronic structures of the quantum critical superconductor beta-YbAlB4 and
its polymorph alpha-YbAlB4 are investigated by using bulk-sensitive hard x-ray
photoemission spectroscopy. From the Yb 3d core level spectra, the values of
the Yb valence are estimated to be ~2.73 and ~2.75 for alpha- and beta-YbAlB4,
respectively, thus providing clear evidence for valence fluctuations. The
valence band spectra of these compounds also show Yb2+ peaks at the Fermi
level. These observations establish an unambiguous case of a strong mixed
valence at quantum criticality for the first time among heavy fermion systems,
calling for a novel scheme for a quantum critical model beyond the conventional
Doniach picture in beta-YbAlB4.Comment: 4 pages, 3 figures, revised version accepted for publication in PR
Evolution of DNA Double-Strand Break Repair by Gene Conversion: Coevolution Between a Phage and Restriction-Modification System
The necessity to repair genome damage has been considered to be an immediate factor responsible for the origin of sex. Indeed, attack by a cellular restriction enzyme of invading DNA from several bacteriophages initiates recombinational repair by gene conversion if there is homologous DNA. In the present work, we modeled the interaction between a bacteriophage and a bacterium carrying a restriction enzyme as antagonistic coevolution. We assume a locus on the bacteriophage genome has either a restriction-sensitive or a -resistant allele, and another locus determines whether it is recombination/repair-proficient or -defective. A restriction break can be repaired by a co-infecting phage genome if one of them is recombination/repair-proficient. We define the fitness of phage (resistant/sensitive and repair-positive/-negative) genotypes and bacterial (restriction-positive/-negative) genotypes by assuming random encounter of the genotypes, with a given probabilities of single and double infections, and the costs of resistance, repair and restriction. Our results show the evolution of the repair allele depends on b1 / b0 , the ratio of the burst size b1 under damage to host cell physiology induced by an unrepaired double-strand break to the default burst size b0 . It was not until this effect was taken into account that the evolutionary advantage of DNA repair became apparent
Rare earth element geochemistry in zircons from basaltic eucrites.
第2回極域科学シンポジウム/第34回南極隕石シンポジウム 11月18日(金) 国立国語研究所 2階講
FINITE ELEMENT ANALYSIS USING A HIERARCHAL DECOMPOSITION FOR THE INTERACTION OF STRUCTURE, FLUID AND ELECTROSTATIC FIELD IN MEMS
In this study, a hierarchal decomposition for the interaction of the structure, fluid and electrostatic field or the structure-fluid-electrostatic interaction, which is one of typical phenomena in micro-electro-mechanical system (MEMS), is proposed in order to solve it efficiently. The proposed decomposition partitions the structure-fluid-electrostatic interaction into the fluid-structure interaction (FSI) and the electrostatic field, and, moreover, splits the FSI into the velocity and fluid pressure fields. In this way, the whole interaction system is decomposed into the three fields in a hierarchal way. The proposed decomposition is implemented using a finite element method and is applied to a micro cantilever beam actuated by the electrostatic force in air. It follows from the comparison among the results for the structure-fluid-electrostatic interaction, the FSI and the experiment that the proposed method taking into account the full-interaction can predict the vibration characteristic of the MEMS accurately.Ⅵ International Conference on Computational Methods for Coupled Problems in Science and Engineering (COUPLED PROBLEMS 2015), 18 - 20 May, 2015, Venice, Ital
Finite element analysis using a hierarchal decomposition for the interaction of structure, fluid and electrostatic field in mems
In this study, a hierarchal decomposition for the interaction of the structure, fluid
and electrostatic field or the structure-fluid-electrostatic interaction, which is one of typical
phenomena in micro-electro-mechanical system (MEMS), is proposed in order to solve it
efficiently. The proposed decomposition partitions the structure-fluid-electrostatic interaction
into the fluid-structure interaction (FSI) and the electrostatic field, and, moreover, splits the
FSI into the velocity and fluid pressure fields. In this way, the whole interaction system is
decomposed into the three fields in a hierarchal way. The proposed decomposition is
implemented using a finite element method and is applied to a micro cantilever beam actuated
by the electrostatic force in air. It follows from the comparison among the results for the
structure-fluid-electrostatic interaction, the FSI and the experiment that the proposed method
taking into account the full-interaction can predict the vibration characteristic of the MEMS
accurately
The Effective Particle-Hole Interaction and the Optical Response of Simple Metal Clusters
Following Sham and Rice [L. J. Sham, T. M. Rice, Phys. Rev. 144 (1966) 708]
the correlated motion of particle-hole pairs is studied, starting from the
general two-particle Greens function. In this way we derive a matrix equation
for eigenvalues and wave functions, respectively, of the general type of
collective excitation of a N-particle system. The interplay between excitons
and plasmons is fully described by this new set of equations. As a by-product
we obtain - at least a-posteriori - a justification for the use of the TDLDA
for simple-metal clusters.Comment: RevTeX, 15 pages, 5 figures in uufiles format, 1 figure avaible from
[email protected]
The bornavirus-derived human protein EBLN1 promotes efficient cell cycle transit, microtubule organisation and genome stability.
It was recently discovered that vertebrate genomes contain multiple endogenised nucleotide sequences derived from the non-retroviral RNA bornavirus. Strikingly, some of these elements have been evolutionary maintained as open reading frames in host genomes for over 40 million years, suggesting that some endogenised bornavirus-derived elements (EBL) might encode functional proteins. EBLN1 is one such element established through endogenisation of the bornavirus N gene (BDV N). Here, we functionally characterise human EBLN1 as a novel regulator of genome stability. Cells depleted of human EBLN1 accumulate DNA damage both under non-stressed conditions and following exogenously induced DNA damage. EBLN1-depleted cells also exhibit cell cycle abnormalities and defects in microtubule organisation as well as premature centrosome splitting, which we attribute in part, to improper localisation of the nuclear envelope protein TPR. Our data therefore reveal that human EBLN1 possesses important cellular functions within human cells, and suggest that other EBLs present within vertebrate genomes may also possess important cellular functions
Hiding solutions in random satisfiability problems: A statistical mechanics approach
A major problem in evaluating stochastic local search algorithms for
NP-complete problems is the need for a systematic generation of hard test
instances having previously known properties of the optimal solutions. On the
basis of statistical mechanics results, we propose random generators of hard
and satisfiable instances for the 3-satisfiability problem (3SAT). The design
of the hardest problem instances is based on the existence of a first order
ferromagnetic phase transition and the glassy nature of excited states. The
analytical predictions are corroborated by numerical results obtained from
complete as well as stochastic local algorithms.Comment: 5 pages, 4 figures, revised version to app. in PR
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