206 research outputs found
The fate of porcine sperm CRISP2 from the perinuclear theca before and after in vitro fertilization
In a previous study, we reported that porcine sperm cysteine-rich secretory protein 2 (CRISP2) is localized in the post-acrosomal sheath-perinuclear theca (PT) as reduction-sensitive oligomers. In the current study, the decondensation and removal of CRISP2 was investigated during in vitro sperm capacitation, after both the induction of the acrosome reaction and in vitro fertilization. Confocal immunofluorescent imaging revealed that additional CRISP2 fluorescence appeared on the apical ridge and on the equatorial segment (EqS) of the sperm head following capacitation, likely due to cholesterol removal. After an ionophore A23187-induced acrosome reaction, CRISP2 immunofluorescence disappeared from the apical ridge and the EqS area partly not only owing to the removal of the acrosomal shroud vesicles, but to its presence in a subdomain of EqS. The fate of sperm head CRISP2 was further examined post-fertilization. In vitro matured porcine oocytes were co-incubated with boar sperm cells for 6-8 h and the zygotes were processed for CRISP2 immunofluorescent staining. Notably, decondensation of CRISP2, and thus of the sperm PT, occurred while the sperm nucleus was still fully condensed. CRISP2 was no longer detectable in fertilized oocytes in which sperm nuclear decondensation and paternal pronucleus formation were apparent. This rapid dispersal of CRISP2 in the PT is likely regulated by redox reactions for which its cysteine-rich domain is sensitive. Reduction of disulfide bridges within CRISP2 oligomers may be instrumental for PT dispersal and elimination
The Weyl bundle as a differentiable manifold
Construction of an infinite dimensional differentiable manifold not modelled on any Banach space is proposed. Definition, metric
and differential structures of a Weyl algebra and a Weyl algebra bundle are
presented. Continuity of the -product in the Tichonov topology is
proved. Construction of the -product of the Fedosov type in terms of theory
of connection in a fibre bundle is explained.Comment: 31 pages; revised version - some typoes have been eliminated,
notation has been simplifie
Weyl-Underhill-Emmrich quantization and the Stratonovich-Weyl quantizer
Weyl-Underhill-Emmrich (WUE) quantization and its generalization are
considered. It is shown that an axiomatic definition of the Stratonovich-Weyl
(SW) quantizer leads to severe difficulties. Quantization on the cylinder
within the WUE formalism is discussed.Comment: 15+1 pages, no figure
The rigged Hilbert space approach to the Lippmann-Schwinger equation. Part II: The analytic continuation of the Lippmann-Schwinger bras and kets
The analytic continuation of the Lippmann-Schwinger bras and kets is obtained
and characterized. It is shown that the natural mathematical setting for the
analytic continuation of the solutions of the Lippmann-Schwinger equation is
the rigged Hilbert space rather than just the Hilbert space. It is also argued
that this analytic continuation entails the imposition of a time asymmetric
boundary condition upon the group time evolution, resulting into a semigroup
time evolution. Physically, the semigroup time evolution is simply a (retarded
or advanced) propagator.Comment: 32 pages, 3 figure
The rigged Hilbert space approach to the Lippmann-Schwinger equation. Part I
We exemplify the way the rigged Hilbert space deals with the
Lippmann-Schwinger equation by way of the spherical shell potential. We
explicitly construct the Lippmann-Schwinger bras and kets along with their
energy representation, their time evolution and the rigged Hilbert spaces to
which they belong. It will be concluded that the natural setting for the
solutions of the Lippmann-Schwinger equation--and therefore for scattering
theory--is the rigged Hilbert space rather than just the Hilbert space.Comment: 34 pages, 1 figur
Deformation Quantization of Bosonic Strings
Deformation quantization of bosonic strings is considered. We show that the
light-cone gauge is the most convenient classical description to perform the
quantization of bosonic strings in the deformation quantization formalism.
Similar to the field theory case, the oscillator variables greatly facilitates
the analysis. The mass spectrum, propagators and the Virasoro algebra are
finally described within this deformation quantization scheme.Comment: 33+1 pages, harvmac file, no figure
Relativistic resonances: Their masses, widths, lifetimes, superposition, and causal evolution
Whether one starts form the analytic S-matrix definition or the requirement
of gauge parameter independence in renormalization theory, a relativistic
resonance is given by a pole at a complex value s of energy squared. The
complex number s does not define the mass and width separately and this
definition does not lead to interfering Breit-Wigner if two or more resonances
are involved. To accomplish both we invoke the decaying particle aspect of a
resonance and associate to each pole a space of relativistic Gamow kets which
transform irreducibly under causal Poincare transformations. A Gamow state has
an exponential time evolution and one can choose of the many possible width
parameters, that parameter as the width of the relativistic resonance which
equals the inverse lifetime. This uniquely defines the mass and width
parameters for a relativistic resonance. Two or more poles in the same partial
wave are given by the sum of Breit-Wigners in the scattering amplitude and by a
superposition of Gamow vectors with each Gamow vector corresponding to one
Breit-Wigner. In addition to the sum of Breit-Wigners the scattering amplitude
contains a background amplitude representing direct production of the final
state (contact terms).This contact amplitude is associated to a background
vector which is a continuous superposition of Lippmann-Schwinger states.
Omitting this continuum gives the Weisskopf-Wigner approximation.Comment: 22 pages, REVTe
Phase-space formulation of quantum mechanics and quantum state reconstruction for physical systems with Lie-group symmetries
We present a detailed discussion of a general theory of phase-space
distributions, introduced recently by the authors [J. Phys. A {\bf 31}, L9
(1998)]. This theory provides a unified phase-space formulation of quantum
mechanics for physical systems possessing Lie-group symmetries. The concept of
generalized coherent states and the method of harmonic analysis are used to
construct explicitly a family of phase-space functions which are postulated to
satisfy the Stratonovich-Weyl correspondence with a generalized traciality
condition. The symbol calculus for the phase-space functions is given by means
of the generalized twisted product. The phase-space formalism is used to study
the problem of the reconstruction of quantum states. In particular, we consider
the reconstruction method based on measurements of displaced projectors, which
comprises a number of recently proposed quantum-optical schemes and is also
related to the standard methods of signal processing. A general group-theoretic
description of this method is developed using the technique of harmonic
expansions on the phase space.Comment: REVTeX, 18 pages, no figure
On two superintegrable nonlinear oscillators in N dimensions
We consider the classical superintegrable Hamiltonian system given by
, where U
is known to be the "intrinsic" oscillator potential on the Darboux spaces of
nonconstant curvature determined by the kinetic energy term T and parametrized
by {\lambda}. We show that H is Stackel equivalent to the free Euclidean
motion, a fact that directly provides a curved Fradkin tensor of constants of
motion for H. Furthermore, we analyze in terms of {\lambda} the three different
underlying manifolds whose geodesic motion is provided by T. As a consequence,
we find that H comprises three different nonlinear physical models that, by
constructing their radial effective potentials, are shown to be two different
nonlinear oscillators and an infinite barrier potential. The quantization of
these two oscillators and its connection with spherical confinement models is
briefly discussed.Comment: 11 pages; based on the contribution to the Manolo Gadella Fest-60
years-in-pucelandia, "Recent advances in time-asymmetric quantum mechanics,
quantization and related topics" hold in Valladolid (Spain), 14-16th july
201
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