7,977 research outputs found
Study of Radiative Leptonic D Meson Decays
We study the radiative leptonic meson decays of D^+_{(s)}\to
\l^+\nu_{\l}\gamma (\l=e,\mu,\tau), and D^0\to
\l^+\l^-\gamma () within the light front quark model. In the standard
model, we find that the decay branching ratios of , and
are (), (), and
(), and that of D^0\to\l^+\l^-\gamma (\l=e,\mu) and
are and ,
respectively.Comment: 23 pages, 6 Figures, LaTex file, a reference added, to be published
in Mod. Phys. Lett.
Screening of degradative plasmids from Arthrobacter sp. HW08 and their ability to degrade swainsonine
Arthrobacter sp. HW08 is capable of swainsonine (SW) degradation with high efficiency. The aim of this study was to screen the degradative plasmids from Arthrobacter sp. HW08 and investigate their ability of degrading SW. A genomic library of Arthrobacter sp. HW08 was successfully constructed by BamHI restriction digestion of genomic DNA and pUC19 vector, ligation and transformation into DH5. Five plasmids of different sizes were screened from 100 genomic library strains, and were named as pUCSW-1, pUCSW-2, pUCSW-3, pUCSW-4 and pUCSW-5, and their insertion elements had sizes of 6 684, 5 093, 136, 1 452 and 2 082 bp, respectively. They contained 7 major open reading frames. SW (400 mg l-1), as only carbon source, cultivated with the mixture of the five plasmid-transformants was degraded within 6 h. The degrading capability was equivalent to that of strain HW08. SW degradative ability of minimum combinations was pUCSW-2, 3, 5 > pUCSW-1, 2, 4 > pUCSW-1, 2, 5 > pUCSW-1, 3, 5, which were all slower than that of strain HW08. Any two or single transformant had no degradative ability. The results of this study support the search of the key genes of SW degradation and the investigating mechanism of SW biodegradation or exploration of its metabolic pathway, and even construction of transgene engineering bacteria to protect animals from lesion when locoweed is consumed.Key words: Swainsonine, biodegradation, degradative plasmids, Arthrobacter sp. HW08
Study of Long Distance Contributions to
We calculate long distance contributions to $K\to\pi\nu\bar{\nu}\,,\
\pi\pi\nu\bar{\nu}\pi\pi\pi\nu\bar{\nu}K\to \pi\nu\bar{\nu}K\to \pi\pi\nu\bar{\nu}$ in the chiral logarithmic
approximation are at least seven orders of magnitude suppressed relative to
those from the short distance parts. The long distance effects in this class of
decays are therefore negligible.Comment: 13 pages, LaTeX fil
CP Violation in Fermion Pair Decays of Neutral Boson Particles
We study CP violation in fermion pair decays of neutral boson particles with
spin 0 or 1. We study a new asymmetry to measure CP violation in decays and discuss the possibility of measuring it
experimentally. For the spin-1 particles case, we study CP violation in the
decays of to octet baryon pairs. We show that these decays can
be used to put stringent constraints on the electric dipole moments of
, and .Comment: 14p, OZ-93/22, UM-93/89, OITS 51
Entanglement of Nambu Spinors and Bell Inequality Test Without Beam Splitters
The identification of electronic entanglement in solids remains elusive so
far, which is owed to the difficulty of implementing spinor-selective beam
splitters with tunable polarization direction. Here, we propose to overcome
this obstacle by producing and detecting a particular type of entanglement
encoded in the Nambu spinor or electron-hole components of quasiparticles
excited in quantum Hall edge states. Due to the opposite charge of electrons
and holes, the detection of the Nambu spinor translates into a charge-current
measurement, which eliminates the need for beam splitters and assures a high
detection rate. Conveniently, the spinor correlation function at fixed
effective polarizations derives from a single current-noise measurement, with
the polarization directions of the detector easily adjusted by coupling the
edge states to a voltage gate and a superconductor, both having been realized
in experiments. We show that the violation of Bell inequality occurs in a large
parameter region. Our work opens a new route for probing quasiparticle
entanglement in solid-state physics exempt from traditional beam splitters.Comment: 7 pages, 2 figures, the version published on PR
A systematic study of Zr and Sn isotopes in the Relativistic Mean Field theory
The ground-state properties of Zr and Sn isotopes are studied within the
relativistic mean field theory. Zr and Sn isotopes have received tremendous
attention due to various reasons, including the predicted giant halos in the
neutron-rich Zr isotopes, the unique feature of being robustly spherical in the
region of Sn Sn and the particular interest of Sn
isotopes to nuclear astrophysics. Furthermore, four (semi-) magic neutron
numbers, 40, 50, 82 and 126, make these two isotopic chains particularly
important to test the pairing correlations and the deformations in a
microscopic model. In the present work, we carry out a systematic study of Zr
and Sn isotopes from the proton drip line to the neutron drip line with
deformation effects, pairing correlations and blocking effects for nuclei with
odd number of neutrons properly treated. A constrained calculation with
quadrupole deformations is performed to find the absolute minimum for each
nucleus on the deformation surface. All ground-state properties, including the
separation energies, the odd-even staggerings, the nuclear radii, the
deformations and the single-particle spectra are analyzed and discussed in
detail.Comment: the final version to appear in Modern Physics Letters A. more
figures, discussions, and references added. the data remain unchange
Zoolexis in Semantic Aspect (by Example of Nouns Derived from Zoonyms)
The article is devoted to semantic analysis zoonymic vocabulary of the Russian language. The paper presents definitions of terms zoonym and zoolexis . The characteristic of Russian nouns derived from zoonyms is given from the point of view of grammatical semantics. In accordance with the nature of grammatical semantics of nouns derived from zoonyms their semantic classes are distinguished. The focus is on the description of the whole semantic groups of nouns derived from zoonyms with a particular meaning. The relevance of the study is determined by the fact that nouns derived from zoonyms with the meaning of a particular item represent a considerable variety among all nouns derived from zoonyms (383 of 489 recorded in derivational dictionary) and are an important part of zoonymic vocabulary in nominative and communicative aspect. On the basis of definition and contextual analysis of lexical units the authors divided them into groups. It is shown that the semantic grouping of nouns derived from zoonyms with the specific meaning depend on belonging to a lexico-grammatical category of animate or inanimate nouns, as lexical representatives of each category form different semantic groups that have certain characteristics. The novelty of the research is seen in the fact that for the first time the Russian nouns derived from zoonyms and naming animals fully analysed from the point of view of semantics
Generalized r-matrix structure and algebro-geometric solution for integrable systems
The purpose of this paper is to construct a generalized r-matrix structure of
finite dimensional systems and an approach to obtain the algebro-geometric
solutions of integrable nonlinear evolution equations (NLEEs). Our starting
point is a generalized Lax matrix instead of usual Lax pair. The generalized
r-matrix structure and Hamiltonian functions are presented on the basis of
fundamental Poisson bracket. It can be clearly seen that various nonlinear
constrained (c-) and restricted (r-) systems, such as the c-AKNS, c-MKdV,
c-Toda, r-Toda, c-Levi, etc, are derived from the reduction of this structure.
All these nonlinear systems have {\it r}-matrices, and are completely
integrable in Liouville's sense. Furthermore, our generalized structure is
developed to become an approach to obtain the algebro-geometric solutions of
integrable NLEEs. Finally, the two typical examples are considered to
illustrate this approach: the infinite or periodic Toda lattice equation and
the AKNS equation with the condition of decay at infinity or periodic boundary.Comment: 41 pages, 0 figure
- …