1,880,526 research outputs found

    Father Time. I. Does the Cosmic Microwave Background Radiation Provide a Universal Arrow of Time ?

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    The existence of a non-thermodynamic arrow of time was demonstrated in a recent paper (Mod.Phys.Lett. A13, 1265 (1998)), in which a model of non-local Quantum Electrodynamics was formulated through the principle of gauge invariance. In this paper we show that the Cosmic Microwave Background Radiation is capable of making every particle of the universe (except those which are not acted upon by an electromagnetic field) follow this arrow of time.Comment: To appear in Mod.Phys.Lett. A. This is a slightly revised version which has been communicated to the EPS-HEP99 Conference at Tampere, Finland (15-21 July 1999) [Abs 12_204

    ‘The party’s over’: critical junctures, crises and the politics of housing policy

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    The key argument set out in this article is that historical and comparative forms of investigation are necessary if we are to better understand the ambitions and scope of contemporary housing interventions. To demonstrate the veracity of our claim, we have set out an analysis of the UK housing polices enacted in the mid-1970s as a basis for comparison with those pursued 40 years later. The article begins with a critical summary of some of the methodological approaches adopted by researchers used to interpret housing policy. In the main section, we present our critical analysis of housing policy reforms (implemented by the Labour government between 1974 and 1979) noting both their achievements and limitations. In the concluding section, we use our interpretation of this period as a basis to judge contemporary housing policy and reflect on the methodological issues that arise from our analysis

    Ground state of Li and Be+^+ using explicitly correlated functions

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    We compare the explicitly correlated Hylleraas and exponential basis sets in the evaluations of ground state of Li and Be+^+. Calculations with Hylleraas functions are numerically stable and can be performed with the large number of basis functions. Our results for ground state energies −7.47806032391010(32)-7.478 060 323 910 10(32), −14.32476317679043(22)-14.324 763 176 790 43(22) of Li and Be+^+ correspondingly, are the most accurate to date. When small basis set is considered, explicitly correlated exponential functions are much more effective. With only 128 functions we obtained about 10−910^{-9} relative accuracy, but the severe numerical instabilities make this basis costly in the evaluation.Comment: 15 page

    Single-crystal growth of underdoped Bi-2223

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    To investigate the origin of the enhanced Tc ({\approx} 110 K) of the trilayer cuprate superconductor Bi2Sr2Ca2Cu3O10+{\delta} (Bi-2223), its underdoped single crystals are a critical requirement. Here, we demonstrate the first successful in-plane resistivity measurements of heavily underdoped Bi-2223 (zero-resistivity temperatures {\approx} 20~35 K). Detailed crystal growth methods, the annealing process, as well as X-ray diffraction (XRD) and magnetic susceptibility measurement results are also reported.Comment: 4 pages, 4 figures, 27th International Symposium on Superconductivity, ISS 2014, to appear in Physics Procedi

    Quantum phase slip interference device based on superconducting nanowire

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    We propose a transistor-like circuit including two serially connected segments of a narrow superconducting nanowire joint by a wider segment with a capacitively coupled gate in between. This circuit is made of amorphous NbSi film and embedded in a network of on-chip Cr microresistors ensuring a sufficiently high external electromagnetic impedance. Assuming a virtual regime of quantum phase slips (QPS)in two narrow segments of the wire, leading to quantum interference of voltages on these segments, this circuit is dual to the dc SQUID. Our samples demonstrated appreciable Coulomb blockade voltage (analog of critical current of the SQUIDs) and periodic modulation of this blockade by an electrostatic gate (analog of flux modulation in the SQUIDs). The model of this QPS transistor is discussed.Comment: 5 pages including 3 figures; in v2 the title was updated, typos were fixed and 4 references adde

    Electron Mass Enhancement due to Anharmonic Local Phonons

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    In order to understand how electron effective mass is enhanced by anharmonic local oscillation of an atom in a cage composed of other atoms, i.e., {\it rattling}, we analyze anharmonic Holstein model by using a Green's function method. Due to the evaluation of an electron mass enhancement factor ZZ, we find that ZZ becomes maximum when zero-point energy is comparable with potential height at which the amplitude of oscillation is rapidly enlarged. Cooperation of such quantum and rattling effects is considered to be a key issue to explain the electron mass enhancement in electron-rattling systems.Comment: 3 pages, 3 figures, to appear in J. Phys. Soc. Jpn. Suppl. (Proceedings for International Conference on Heavy Electrons

    Quadrupole Susceptibility of Gd-Based Filled Skutterudite Compounds

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    It is shown that quadrupole susceptibility can be detected in Gd compounds contrary to our textbook knowledge that Gd3+^{3+} ion induces pure spin moment due to the Hund's rules in an LSLS coupling scheme. The ground-state multiplet of Gd3+^{3+} is always characterized by JJ=7/2, where JJ denotes total angular momentum, but in a jj-jj coupling scheme, one ff electron in jj=7/2 octet carries quadrupole moment, while other six electrons fully occupy jj=5/2 sextet, where jj denotes one-electron total angular momentum. For realistic values of Coulomb interaction and spin-orbit coupling, the ground-state wavefunction is found to contain significant amount of the jj-jj coupling component. From the evaluation of quadrupole susceptibility in a simple mean-field approximation, we point out a possibility to detect the softening of elastic constant in Gd-based filled skutterudites.Comment: 8 pages, 4 figure

    Majorana Fermion Induced Resonant Andreev Reflection

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    We describe experimental signatures of Majorana fermion edge states, which form at the interface between a superconductor and the surface of a topological insulator. If a lead couples to the Majorana fermions through electron tunneling, the Majorana fermions induce \textit{resonant} Andreev reflections from the lead to the grounded superconductor. The linear tunneling conductance is 00 (2e2/h2 e^2/h) if there is an even (odd) number of vortices in the superconductor. Similar resonance occurs for tunneling into the zero mode in the vortex core. We also study the current and noise of a two-lead device.Comment: 4 pages, 3 figures. Discussion on STM tunneling into the Majorana zero mode in the vortex core is adde
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