2,911 research outputs found

    Origin of stabilization of macrotwin boundaries in martensites

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    The origin of stabilization of complex microstructures along macrotwin boundaries in martensites is explained by comparing two models based on Ginzburg-Landau theory. The first model incorporates a geometrically nonlinear strain tensor to ensure that the Landau energy is invariant under rigid body rotations, while the second model uses a linearized strain tensor under the assumption that deformations and rotations are small. We show that the approximation in the second model does not always hold for martensites and that the experimental observations along macrotwin boundaries can only be reproduced by the geometrically nonlinear (exact) theory

    Classification of the phases of 1D spin chains with commuting Hamiltonians

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    We consider the class of spin Hamiltonians on a 1D chain with periodic boundary conditions that are (i) translational invariant, (ii) commuting and (iii) scale invariant, where by the latter we mean that the ground state degeneracy is independent of the system size. We correspond a directed graph to a Hamiltonian of this form and show that the structure of its ground space can be read from the cycles of the graph. We show that the ground state degeneracy is the only parameter that distinguishes the phases of these Hamiltonians. Our main tool in this paper is the idea of Bravyi and Vyalyi (2005) in using the representation theory of finite dimensional C^*-algebras to study commuting Hamiltonians.Comment: 8 pages, improved readability, added exampl

    Unconventional superconductivity in CuxBi2Se3

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    We report point contact measurements in high quality single crystals of Cu0.2Bi2Se3. We observe three different kinds of spectra: (1) Andreev-reflection spectra, from which we infer a superconducting gap size of 0.6mV; (2) spectra with a large gap which closes above Tc at about 10K; and (3) tunneling-like spectra with zero-bias conductance peaks. These tunneling spectra show a very large gap of ~2meV (2Delta/KTc ~ 14)

    Muon diffusion and electronic magnetism in Y2_2Ti2_2O7_7

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    We report a ÎŒ\muSR study in a Y2_2Ti2_2O7_7 single crystal. We observe slow local field fluctuations at low temperature which become faster as the temperature is increased. Our analysis suggests that muon diffusion is present in this system and becomes small below 40 K and therefore incoherent. A surprisingly strong electronic magnetic signal is observed with features typical for muons thermally diffusing towards magnetic traps below ≈100\approx 100 K and released from them above this temperature. We attribute the traps to Ti3+^{3+} defects in the diluted limit. Our observations are highly relevant to the persistent spin dynamics debate on R2R_2Ti2_2O7_7 pyrochlores and their crystal quality

    Ketepatan dan Kecepatan Pembidikan Pisir Penjera pada Latihan Bidik Kering Menggunakan Fuzzy Logic

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    Lesan Tembak Bidik Kering dibuat untuk mendukung tugas pokok TNI AD dalam rangka membantu prajurit pada bidang menembak untuk mendapatkan prajurit yang handal, dimana setiap prajurit harus mahir menembak.Perencanaan dan pembuatan alat dibangun dengan meggunakan alat perangkat keras dan perangkat lunak. Perangkat keras yang digunakan yaitu motor DC, mikrokontroler ATMega16, driver ULN2003, bluetooth, joystick, limit switch dan mekanik. Sedangkan perangkat lunak yang digunakan yaitu Software Code Vision AVR sebagai alat pengendali. Dalam pembuatan alat yang dimaksud supaya dapat berfungsi dengan baik, maka diperlukan pemahaman yang mendalam tentang karakteristik dan cara kerja komponen-komponen yang digunakan. Hal ini perlu dikuasa sebaik-baiknya untuk menghindari kesalan penggunaan komponen yang mengakibatkan kegagalan dalam pembuatan alat.Pada perencanaan hardware akan meliputi seluruh perihal yang digunakan pada sistem. Pada perencanaan software merupakan piranti lunak meliputi flowchart dan software secara umum. Perangkat tersebut saling terintegrasi sehingga dalam kerjanya akan maksimum sesuai apa yang diharapkan.Software ini diharapkan mampu memenuhi tugas pokok TNI AD khususnya keahlian menembak agar lebih efektif, akurat dan tepat dalam melaksanakan latihan menembak di satuan TNI AD

    Evaluation and phytochemical screening and antibacterial activity of Ficus dalhousiae Miq

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    The aim of the present study was to isolate the Extract from the leaves of Ficus dalhousiae Miq and subse-quently evaluate their antibacterial and antifungal activity. The crude various extracts of the plant n-Hexane, Chloroform, Ethyl acetate, Methanol extract was obtained by using continuous soxhlation tech-nique using soxhlet apparatus. The antibacterial activity of plant extract were carried using cup plate method against three bacterial species Staphylococcus aures, Bacillus subtilis, Escherichia coli using agar diffusion method. those are compared with standard reference drug Ciprofloxacin. This study confirmed that bark extracts have more active constituents compare to leaf extracts. by pharmacological evaluation of Ficus dalhousea Miq. Various extracts, most of them are capable of showing moderate antibacterial activity
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