3,858 research outputs found
Pressure-temperature phase diagram of ferromagnetic superconductors
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
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
Pathogenicity, antibiogram and biochemical characteristics of Luminescent Vibrio harveyi, associated with 'Black Shell Disease' of Penaeus monodon
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
Immunomodulatory potential of marine secondary metabolites against bacterial diseases of shrimp
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
Microscopic theories for cubic and tetrahedral superconductors: application to PrOs_4Sb_{12}
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
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
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
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 UGe
We report a detailed study of UGe 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 . The characteristic
changes are exhibited most strongly at an energy scale of around 12 meV (100
cm). They recover their unrenormalized value above and for 40 meV. In contrast no sign of an anomaly is seen at the lower transition
temperature of unknown nature 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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