3,879 research outputs found

    Pressure-temperature phase diagram of ferromagnetic superconductors

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    The symmetry approach to the description of the (P,T) phase diagram of ferromagnet superconductors with triplet pairing is developed. Taking into account the recent experimental observations made on UCoGe it is considered the case of a crystal with orthorhombic structure and strong spin-orbital coupling. It is shown that formation of ferromagnet superconducting state from a superconducting state is inevitably accompanied by the first order type transition.Comment: 4 pages, 1 figur

    One dimensional chain of quantum molecule motors as a mathematical physics model for muscle fibre

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    A quantum chain model of many molecule motors is proposed as a mathematical physics theory on the microscopic modeling of classical force-velocity relation and tension transients of muscle fibre. We proposed quantum many-particle Hamiltonian to predict the force-velocity relation for the slow release of muscle fibre which has no empirical relation yet, it is much more complicate than hyperbolic relation. Using the same Hamiltonian, we predicted the mathematical force-velocity relation when the muscle is stimulated by alternative electric current. The discrepancy between input electric frequency and the muscle oscillation frequency has a physical understanding by Doppler effect in this quantum chain model. Further more, we apply quantum physics phenomena to explore the tension time course of cardiac muscle and insect flight muscle. Most of the experimental tension transients curves found their correspondence in the theoretical output of quantum two-level and three-level model. Mathematically modeling electric stimulus as photons exciting a quantum three-level particle reproduced most tension transient curves of water bug Lethocerus Maximus.Comment: 16 pages, 12 figures, Arguments are adde

    Immunomodulatory potential of marine secondary metabolites against bacterial diseases of shrimp

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    Shrimp disease management using bioactive marine secondary metabolites (MSMs) was developed as a package of practice for the sustainable shrimp farming. Therefore, the effect of MSMs on the host defense factors of shrimp was evaluated in the present study. Findings indicated that Ulva diet significantly increase the defense factors such as haemogram, agglutination index, phagocytic rate, bacterial clearance and serum bactericidal activity of treated shrimps over the control group. Based on the gut bacterial load, Ulva diet was considered as proactive drug whereas Dendrilla diet was determined as a curative agent

    Pathogenicity, antibiogram and biochemical characteristics of Luminescent Vibrio harveyi, associated with 'Black Shell Disease' of Penaeus monodon

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    Bacterial isolation was made from shrimps Penaeus monodon showing characteristic external symptoms of 'black shell disease' from shrimp farms located in southeast coast of India. The isolates were screened on TeBS agar plates and 0/129 for the selective isolation of Vibrio sp. Based on the morphological, biochemical and physiological characteristics, the isolate (RJM5) was characterized as luminescent Vibrio harveyi." Antibiogram of V. Imrueyi indicated that it was highly sensitive to chloramphenicol. ciprofloxacin, nalidixic acid and streptomycin. The pathogenicity studies confirmed that the isolate (V.harveyi) was moderately virulent

    Microscopic theories for cubic and tetrahedral superconductors: application to PrOs_4Sb_{12}

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    We examine weak-coupling theory for unconventional superconducting states of cubic or tetrahedral symmetry for arbitrary order parameters and Fermi surfaces and identify the stable states in zero applied field. We further examine the possibility of having multiple superconducting transitions arising from the weak breaking of a higher symmetry group to cubic or tetrahedral symmetry. Specifically, we consider two higher symmetry groups. The first is a weak crystal field theory in which the spin-singlet Cooper pairs have an approximate spherical symmetry. The second is a weak spin orbit coupling theory for which spin-triplet Cooper pairs have a cubic orbital symmetry and an approximate spherical spin rotational symmetry. In hexagonal UPt_3, these theories easily give rise to multiple transitions. However, we find that for cubic materials, there is only one case in which two superconducting transitions occur within weak coupling theory. This sequence of transitions does not agree with the observed properties of PrOs_4Sb_{12}. Consequently, we find that to explain two transitions in PrOs_4Sb_{12} using approximate higher symmetry groups requires a strong coupling theory. In view of this, we finally consider a weak coupling theory for which two singlet representations have accidentally nearly degenerate transition temperatures (not due to any approximate symmetries). We provide an example of such a theory that agrees with the observed properties of PrOs_4Sb_{12}.Comment: 11 pages,1 figur

    Additive twists of Fourier coefficients of symmetric-square lifts

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    We study the sum of additively twisted Fourier coefficients of a symmetric-square lift of a Maass form invariant under the full modular group. Our bounds are uniform in terms of the spectral parameter of the Maass form, as well as in terms of the additive twist.Comment: 13 pages. v2: fixed the relation between T and t_j on p.2 and added clarification to some reference

    Force Dependence of the Michaelis Constant in a Two-State Ratchet Model for Molecular Motors

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    We present a quantitative analysis of recent data on the kinetics of ATP hydrolysis, which has presented a puzzle regarding the load dependence of the Michaelis constant. Within the framework of coarse grained two-state ratchet models, our analysis not only explains the puzzling data, but provides a modified Michaelis law, which could be useful as a guide for future experiments.Comment: 4 pages, 3 eps figures, accepted for publication on Physical Review Letter

    Observation of a Triangular to Square Flux Lattice Phase Transition in YBCO

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    We have used the technique of small-angle neutron scattering to observe magnetic flux lines directly in an YBCO single crystal at fields higher than previously reported. For field directions close to perpendicular to the CuO2 planes, we find that the flux lattice structure changes smoothly from a distorted triangular co-ordination to nearly perfectly square as the magnetic induction approaches 11 T. The orientation of the square flux lattice is as expected from recent d-wave theories, but is 45 deg from that recently observed in LSCO

    Optical spectra of the heavy fermion uniaxial ferromagnet UGe2_2

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    We report a detailed study of UGe2_{2} single crystals using infrared reflectivity and spectroscopic ellipsometry. The optical conductivity suggests the presence of a low frequency interband transition and a narrow free-carrier response with strong frequency dependence of the scattering rate and effective mass. We observe sharp changes in the low frequency mass and scattering rate below the upper ferromagnetic transition TC=53KT_C = 53 K. The characteristic changes are exhibited most strongly at an energy scale of around 12 meV (100 cm1^{-1}). They recover their unrenormalized value above TCT_C and for ω>\omega > 40 meV. In contrast no sign of an anomaly is seen at the lower transition temperature of unknown nature TxT_x \sim 30 K, observed in transport and thermodynamic experiments. In the ferromagnetic state we find signatures of a strong coupling to the longitudinal magnetic excitations that have been proposed to mediate unconventional superconductivity in this compound
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