The Effect of Side Traps on Ballistic Transistor in Kondo Regime

The effect of side-traps on conductance is calculated in the range of slave-boson mean field theory, especially when there are electrodes on both sides of the conductor. This corresponds to an investigation of transport properties in future ballistic transistors. An intrinsic dip as a result of the interference effect (Fano-Kondo effect) is expected to be observed as one of interesting interplays between physics and engineering devices.Comment: 3 pages, 5 figures. 2006 International Conference on Solid State Devices and Materials (SSDM2006), Sept. 12-15, 2006, Yokohama, Japa

ニワトリ胚頭褶形成時のアクチン局在の解析

At gastrulation, early chicken embryo consists of three germ layers, ectoderm, mesoderm and endoderm, spreading into a planer sheet. At neurula stage, anterior part of the embryo is lifted and makes a fold called the head fold. Along with the head fold formation, a sack-like structure the foregut, is formed on the ventral side and eventually the embryo has a three-dimensional head structure. It has been unclear how the sheet-like embryo starts to fold. To understand the mechanisms involved in making the head fold, I investigated actin localization during formation of head fold, because actin contraction regulates change of shape in cells or tissues. In this study, I observed the changes of structure and actin accumulation during the head fold formation using chicken embryos. First, I found that embryo has two folding points. Posterior hinge is future anterior intestinal portal and anterior one will become the deepest part of the foregut. I name them the head fold hinge and the foregut hinge, respectively. Next, original position of each hinge point was investigated by labeling the midline of the anterior embryo with DiI. The cells at the anterior end of the prechordal plate (PP) were found to become the head fold hinge and at the center of PP contributed to the foregut hinge. From the chicken developmental stages determined by Hamburger and Hamilton (1951) embryos in stage 5 have flat structure and those in stage 6 have the head fold, respectively. To describe folding process fully, I defined the stages between stage 5 and 6 depending on the structure around PP. Based on this stage I analyzed the shape and thickness of embryo and localization of polymerized actin by staining with phalloidin. In stage 5 the embryos were almost flat and actin was weak. Then, strong actin spots appeared on the apical side of the endoderm at PP. Next, embryo around PP became thicker, and actin in the endoderm became much stronger. The cell sheet around PP curved to the dorsal side before folding. After folding, accumulation of strong actin was found on the endoderm at the foregut hinge. The result of strong actin localization in apical side of the endoderm before and after folding around future foregut hinge suggests a possibility that actin may be very important for folding of foregut hinge. At the head fold hinge, strongly actin appeared in the ectoderm after the head fold formation. Therefore, in the head fold formation, actin may maintain the shape after the embryo is folded.ニワトリを含む有羊膜類の初期胚は背側から外胚葉、中胚葉および内胚葉の三層が平たく広がったシート状の構造をしている。平面構造であるステージ5から約4時間後、ステージ6になると胚の前方が背側に盛り上がり、頭褶と呼ばれるひだを作る。それに伴って内胚葉側に前腸と呼ばれる袋状の構造ができ、胚は立体的な頭部を持つようになる。そして後方および側方も折れ曲がることで、胚は胚体外から区別された細長い構造をとる。私はこの過程で胚の立体化の開始となる、前方の折れ曲がりである頭褶がどのようにしてできるのかに興味をもった。そこでシート状の胚が折れ曲がる時に、どのような力がどこにかかるのかを調べることにした。組織が収縮し立体構造を作る時にはしばしばアクチンの集積が見られることから、本研究ではニワトリ胚を用いて頭褶形成によって変化する構造とともに、どこにアクチンの集積が見られるかファロイジン染色によって調べた。まずアクチン局在の変化を見る前に、胚のどの部分が折れ曲がり、頭褶になるのかを調べた。原腸陥入後のステージ5では前方の正中線に沿って前から脊索前板(PP)、頭突起(HP)、ヘンゼン結節(HN)が並ぶ。そこでステージ5とステージ6の間の胚の腹側前方を正中線に沿ってDiIでラベルし、これをステージ6まで培養した。その結果、折れ曲がった胚には前腸門と、前腸の最も深い場所の2点でヒンジポイントが存在し、本研究ではそれぞれ頭褶側ヒンジポイント、前腸側ヒンジポイントと名付けた。PPの前端の細胞は頭褶側ヒンジポイントとなることがわかった。また、PPの中央付近の細胞は前腸内に寄与し前腸ヒンジポイントとなった。次に胚をファロイジンで染色し、屈曲前後のステージを詳細に分けて重合型アクチンが局在する場所や胚の厚さの変化を比較した。観察は将来の頭褶側、前腸側ヒンジポイントを中心に行った。ステージ5では胚はほぼ平面でアクチンは全体的に弱かった。しかし発生が進むと徐々にPP上の特に内胚葉頂端側で斑点状の強い領域が出現し、アクチンが弱く非常に薄いPPの前方と差が生じた。折れ曲がる直前のPP内は非常にアクチンが強く、その領域は背側に盛り上がり厚くなった。またPPの後端からHPの先端は外胚葉内胚葉共にアクチンが強く、胚は少し薄かった。折れ曲がると、アクチンが強い領域は前腸側のヒンジポイントに集中し、その後方は斑点状であった。よって前腸形成では、ステージ5以降にPP付近の内胚葉で強いアクチン局在が見られた。そして平面だったシートの肥厚と、前腸側ヒンジポイントにおける内胚葉組織の収縮の両方にアクチンが関与する可能性がある。また胚が折れ曲がり、前腸が形成され始めてから、前腸門の背側に位置する頭褶側ヒンジポイントの外胚葉に、アクチンが強く現れた。このことから頭褶形成では、胚が折れ曲がった後の形状維持にアクチンが関わる可能性が考えられる。首都大学東京, 2018-03-25, 修士（理学）首都大学東

Quantum Computer Using Coupled Quantum Dot Molecules

We propose a method for implementation of a quantum computer using artificial molecules. The artificial molecule consists of two coupled quantum dots stacked along z direction and one single electron. One-qubit and two-qubit gates are constructed by one molecule and two coupled molecules, respectively.The ground state and the first excited state of the molecule are used to encode the |0> and |1> states of a qubit. The qubit is manipulated by a resonant electromagnetic wave that is applied directly to the qubit through a microstrip line. The coupling between two qubits in a quantum controlled NOT gate is switched on (off) by floating (grounding) the metal film electrodes. We study the operations of the gates by using a box-shaped quantum dot model and numerically solving a time-dependent Schridinger equation, and demonstrate that the quantum gates can perform the quantum computation. The operating speed of the gates is about one operation per 4ps. The reading operation of the output of the quantum computer can be performed by detecting the polarization of the qubits.Comment: 18 pages, 7 figures, submitted to Jpn. J. Appl. Phys, please send your e-mail to Nan-Jian Wu <[email protected]

Chiral spin-orbital liquids with nodal lines

Strongly correlated materials with strong spin-orbit coupling hold promise for realizing topological phases with fractionalized excitations. Here we propose a chiral spin-orbital liquid as a stable phase of a realistic model for heavy-element double perovskites. This spin liquid state has Majorana fermion excitations with a gapless spectrum characterized by nodal lines along the edges of the Brillouin zone. We show that the nodal lines are topological defects of a non-Abelian Berry connection and that the system exhibits dispersing surface states. We discuss some experimental signatures of this state and compare them with properties of the spin liquid candidate Ba_2YMoO_6.Comment: 5 pages + supplementary materia

The design and development of a two-dimensional adaptive truss structure

The functional model of a two dimensional adaptive truss structure which can purposefully change its geometrical configuration is introduced. The details of design and fabrication such as kinematic analysis, dynamic characteristics analysis and some test results are presented for the demonstration of this two dimensional truss concept

Chiral Spin-orbital Liquids With Nodal Lines

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Strongly correlated materials with strong spin-orbit coupling hold promise for realizing topological phases with fractionalized excitations. Here, we propose a chiral spin-orbital liquid as a stable phase of a realistic model for heavy-element double perovskites. This spin liquid state has Majorana fermion excitations with a gapless spectrum characterized by nodal lines along the edges of the Brillouin zone. We show that the nodal lines are topological defects of a non-Abelian Berry connection and that the system exhibits dispersing surface states. We discuss some experimental signatures of this state and compare them with properties of the spin liquid candidate Ba2YMoO6.117Brazilian agency FAPESPBrazilian agency CNPqFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq