35,828 research outputs found
Chilodonella cyprini (Moroff, 1902) [Translation from: Izv.gos.nauchno-issled.Inst.ozer.i rech.ryb.kh-va 49 25-28, 1959]
The ciliated protozoan Chilodonella cyprini is described. Chilodon parasitizes the body, gills and fins of fishes. The infusoria produce irritation of the integument and strengthened mucous secretion. The sparse knowledsge of the ecology of chilodon is summarised and some advice on the struggle against cholodoniasis in carp given
On Extracting Heavy Quark Parameters from Moments with Cuts
We point out that applying the photon energy cut significantly modifies the
moments of energy spectrum in B->X_s+gamma decays, with a certain class of
effects not accounted for in the mostly used OPE expressions. This leads to a
systematic bias in the extracted values of the b quark mass and other heavy
quark parameters. The apparent b quark mass increases typically by 70MeV or
more, together with an even more dramatic downward shift in the kinetic
expectation value. Accounting for these cut-related shifts brings different
measurements into a good agreement, when the OPE-based theory employs the
robust approach. These nonperturbative effects are exponential in the effective
hardness severely lowered by high cuts, and do not signify a breakdown of the
1/m_b expansion itself. Similar effects in semileptonic b->c decays are briefly
addressed. We stress the utility of the second moment of E_gamma once these
effects are incorporated.Comment: 8 pages, LaTeX, two figure. Contributed to the Lepton-Photon
Conference, 2003, FNA
Singular vectors by Fusions in affine su(2)
Explicit expressions for the singular vectors in the highest weight
representations of are obtained using the fusion formalism of
conformal field theory.Comment: 7 page
Harmonic generation by atoms in circularly polarized laser fields: far-off and near resonances regimes
The generation of harmonics by atoms interacting with two circularly
polarized and frequency related laser fields is addressed through ab initio
numerical simulations. A detailed charaterization of a few specific harmonics
is given. In particular, the two different cases where the total energy
absorbed through photons is far-off or close to the energy gap between
different atomic states are investigated. It is found that the conversion
efficiency in the harmonic generation is strongly dependent on the inner atomic
structure and in certain specific cases it can be significantly enhanced within
a small frequency range.Comment: Submitted to Appl. Phys. B, 4 page
Superconductivity in the Kondo lattice model
We study the Kondo lattice model with additional attractive interaction
between the conduction electrons within the dynamical mean-field theory using
the numerical renormalization group to solve the effective quantum impurity
problem. In addition to normal-state and magnetic phases we also allow for the
occurrence of a superconducting phase. In the normal phase we observe a very
sensitive dependence of the low-energy scale on the conduction-electron
interaction. We discuss the dependence of the superconducting transition on the
interplay between attractive interaction and Kondo exchange.Comment: Submitted to ICM 2009 Conference Proceeding
Towards pair production near threshold with unstable particle effective theory
We illustrate the use of effective theory techniques to describe processes
involving unstable particles close to resonance. First, we present the main
ideas in the context of a scalar resonance in an Abelian gauge-Yukawa model. We
then outline the necessary modifications to describe W-pair production close to
threshold in electron-positron collisions.Comment: Invited talk given at the 11th International Conference on QCD,
Montpellier, France (5--10th July 2004
Large magnetoresistance in the antiferromagnetic semi-metal NdSb
There has been considerable interest in topological semi-metals that exhibit
extreme magnetoresistance (XMR). These have included materials lacking
inversion symmetry such as TaAs, as well Dirac semi-metals such as Cd3As2.
However, it was reported recently that LaSb and LaBi also exhibit XMR, even
though the rock-salt structure of these materials has inversion symmetry, and
the band-structure calculations do not show a Dirac dispersion in the bulk.
Here, we present magnetoresistance and specific heat measurements on NdSb,
which is isostructural with LaSb. NdSb has an antiferromagnetic groundstate,
and in analogy with the lanthanum monopnictides, is expected to be a
topologically non-trivial semi-metal. We show that NdSb has an XMR of 10^4 %,
even within the AFM state, illustrating that XMR can occur independently of the
absence of time reversal symmetry breaking in zero magnetic field. The
persistence of XMR in a magnetic system offers promise of new functionality
when combining topological matter with electronic correlations. We also find
that in an applied magnetic field below the Neel temperature there is a first
order transition, consistent with evidence from previous neutron scattering
work.Comment: 5 pages, 6 figure
Efficient Magnetization Reversal with Noisy Currents
We propose to accelerate reversal of the ferromagnetic order parameter in
spin valves by electronic noise. By solving the stochastic equations of motion
we show that the current-induced magnetization switching time is drastically
reduced by a modest level of externally generated current (voltage) noise. This
also leads to a significantly lower power consumption for the switching
process.Comment: 4 pages, 3 figure
A first step toward higher order chain rules in abelian functor calculus
One of the fundamental tools of undergraduate calculus is the chain rule. The
notion of higher order directional derivatives was developed by Huang,
Marcantognini, and Young, along with a corresponding higher order chain rule.
When Johnson and McCarthy established abelian functor calculus, they proved a
chain rule for functors that is analogous to the directional derivative chain
rule when . In joint work with Bauer, Johnson, and Riehl, we defined an
analogue of the iterated directional derivative and provided an inductive proof
of the analogue to the chain rule of Huang et al.
This paper consists of the initial investigation of the chain rule found in
Bauer et al., which involves a concrete computation of the case when . We
describe how to obtain the second higher order directional derivative chain
rule for abelian functors. This proof is fundamentally different in spirit from
the proof given in Bauer et al. as it relies only on properties of cross
effects and the linearization of functors
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