792 research outputs found

    Singular maps on exotic 4-manifold pairs

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    We show examples of pairs of smooth, compact, homeomorphic 4-manifolds, whose diffeomorphism types are distinguished by the topology of the singular sets of smooth stable maps defined on them. In this distinction we rely on results from Seiberg-Witten theory.Comment: 17 pages, 6 figures, minor modifications following referee's comment

    The Qupit Stabiliser ZX-travaganza: Simplified Axioms, Normal Forms and Graph-Theoretic Simplification

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    We present a smorgasbord of results on the stabiliser ZX-calculus for odd prime-dimensional qudits (i.e. qupits). We derive a simplified rule set that closely resembles the original rules of qubit ZX-calculus. Using these rules, we demonstrate analogues of the spider-removing local complementation and pivoting rules. This allows for efficient reduction of diagrams to the affine with phases normal form. We also demonstrate a reduction to a unique form, providing an alternative and simpler proof of completeness. Furthermore, we introduce a different reduction to the graph state with local Cliffords normal form, which leads to a novel layered decomposition for qupit Clifford unitaries. Additionally, we propose a new approach to handle scalars formally, closely reflecting their practical usage. Finally, we have implemented many of these findings in DiZX, a new open-source Python library for qudit ZX-diagrammatic reasoning.Comment: 44 pages, lots of figures, accepted to QPL 202

    Basidiocarp and mycelium morphology of Ganoderma lucium Karst. Strains isolated in Hungary

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    Morphological, anatomical and cultural characteristics of 14 Ganoderma lucidum(Fr.) Karst strains isolated in Hungary have been investigated. Macroscopically the basidiocarps of the Hungarian strains are absolutely identical with those of described previously about the Ganoderma lucidumspecies-complex. Microscopic features of the fruitbodies and basidiospores showed some differences from the typical G. lucidumspecies. Pilocystidia, forming a homogenous layer on the surface of the pileus, have smooth heads without protrusions and stalks not ramifying. Cell wall pillar density and width of the basidiospores also differ from that of regarded to be characteristic toG. lucidum. Although according to several authors chlamydospore formation is a characteristic feature of G. lucidumit has not been observed in mycelial cultures of the Hungarian strains. Antagonistic reactions between the Hungarian and Far Eastern G. lucidumisolates were mostly similar to the interspecific reactions between the two speciesG. lucidumand G. applanatumand corresponded only in a few cases to the interactions within one species. Our results suggest that the Hungarian strains significantly differ from the Far Eastern strains. To determine the taxonomic degree of this divergence genetical examinations should be carried out

    Ancillary science with Ariel: Feasibility and scientific potential of young stellar object observations

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    To investigate the feasibility of ancillary target observations with ESA's Ariel mission, we compiled a list of potentially interesting young stars: FUors, systems harbouring extreme debris discs and a larger sample of young stellar objects showing strong near/mid-infrared excess. These objects can be observed as additional targets in the waiting times between the scheduled exoplanet transit and occultation observations. After analyzing the schedule for Ariel an algorithm was constructed to find the optimal target to be observed in each gap. The selection was mainly based on the slew and stabilization time needed to observe the selected YSO, but it also incorporated the scientific importance of the targets and whether they have already been sufficiently measured. After acquiring an adequately large sample of simulation data, it was concluded that approximately 99.2% of the available -- at least one hour long -- gaps could be used effectively. With an average slewing and stabilization time of about 16.7 minutes between scheduled exoplanet transits and ancillary targets, this corresponds to an additional 2881±562881 \pm 56 hours of active data gathering. When this additional time is used to observe our selected 200 ancillary targets, a typical signal-to-noise ratio of \sim104^4 can be achieved along the whole spectral window covered by Ariel.Comment: Accepted for publication in Experimental Astronom

    Pairing Fluctuation Theory of Superconducting Properties in Underdoped to Overdoped Cuprates

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    We propose a theoretical description of the superconducting state of under- to overdoped cuprates, based on the short coherence length of these materials and the associated strong pairing fluctuations. The calculated TcT_c and the zero temperature excitation gap Δ(0)\Delta(0), as a function of hole concentration xx, are in semi-quantitative agreement with experiment. Although the ratio Tc/Δ(0)T_c/\Delta(0) has a strong xx dependence, different from the universal BCS value, and Δ(T)\Delta(T) deviates significantly from the BCS prediction, we obtain, quite remarkably, quasi-universal behavior, for the normalized superfluid density ρs(T)/ρs(0)\rho_s(T)/\rho_s(0) and the Josephson critical current Ic(T)/Ic(0)I_c(T)/I_c(0), as a function of T/TcT/T_c. While experiments on ρs(T)\rho_s(T) are consistent with these results, future measurements on Ic(T)I_c(T) are needed to test this prediction.Comment: 4 pages, 3 figures, REVTeX, submitted to Phys. Rev. Let

    VHMPID: a new detector for the ALICE experiment at LHC

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    This article presents the basic idea of VHMPID, an upgrade detector for the ALICE experiment at LHC, CERN. The main goal of this detector is to extend the particle identification capabilities of ALICE to give more insight into the evolution of the hot and dense matter created in Pb-Pb collisions. Starting from the physics motivations and working principles the challenges and current status of development is detailed.Comment: 4 pages, 6 figures. To be published in EPJ Web of Conference

    Theory of Scanning Tunneling Spectroscopy of Magnetic-Field-Induced Discrete Nodal States in a D-Wave Superconductor

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    In the presence of an external magnetic field, the low lying elementary excitations of a d-wave superconductor have quantized energy and their momenta are locked near the node direction. It is argued that these discrete states can most likely be detected by a local probe, such as a scanning tunneling microscope. The low temperature local tunneling conductance on the Wigner-Seitz cell boundaries of the vortex lattice is predicted to show peaks spaced as ±n,n=0,1,2,...\pm \sqrt{n}, n ={0,1,2, ...}. The n=0n=0 peak is anomalous, and it is present only if the superconducting order parameter changes sign at certain points on the Fermi surface. Away from the cell boundary, where the superfluid velocity is nonzero, each peak splits, in general, into four peaks, corresponding to the number of nodes in the order parameter.Comment: RevTeX 3.0, 4 pages, 3 figures (included

    Incoherent Pair Tunneling as a Probe of the Cuprate Pseudogap

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    We argue that incoherent pair tunneling in a cuprate superconductor junction with an optimally doped superconducting and an underdoped normal lead can be used to detect the presence of pairing correlations in the pseudogap phase of the underdoped lead. We estimate that the junction characteristics most suitable for studying the pair tunneling current are close to recently manufactured cuprate tunneling devices.Comment: ReVTeX 3.1; 4 pages, 2 EPS figures (included

    Dispersion of the neutron resonance in cuprate superconductors

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    We argue that recently measured downward dispersion of the neutron resonance peak in cuprate superconductors is naturally explained if the resonance is viewed as a spin-1 collective mode in a d-wave superconductor. The reduction of the resonant frequency away from the antiferromagnetic wave vector is a direct consequence of the momentum dependence of the d-wave superconducting gap. When the magnetic correlation length becomes large, the dispersion should become magnon-like, i.e., curve upwards from (pi,pi).Comment: 4 pages, 3 inline PostScript figures. Added reference

    Superconducting transitions from the pseudogap state: d-wave symmetry, lattice, and low-dimensional effects

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    We investigate the behavior of the superconducting transition temperature within a previously developed BCS-Bose Einstein crossover picture. This picture, based on a decoupling scheme of Kadanoff and Martin, further extended by Patton, can be used to derive a simple form for the superconducting transition temperature in the presence of a pseudogap. We extend previous work which addressed the case of s-wave pairing in jellium, to explore the solutions for T_c as a function of variable coupling in more physically relevant situations. We thereby ascertain the effects of reduced dimensionality, periodic lattices and a d-wave pairing interaction. Implications for the cuprate superconductors are discussed.Comment: REVTeX, 11 pages, 6 EPS figures included, Replace with published versio
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