257 research outputs found
Superdeformation and clustering in Ca studied with Antisymmetrized Molecular Dynamics
Deformed states in Ca are investigated with a method of
antisymmetrized molecular dynamics. Above the spherical ground state,
rotational bands arise from a normal deformation and a superdeformation as well
as an oblate deformation. The calculated energy spectra and transition
strengths in the superdeformed band reasonably agree to the experimental data
of the superdeformed band starting from the state at 5.213 MeV. By the
analysis of single-particle orbits, it is found that the superdeformed state
has particle-hole nature of an - configuration. One of new findings is
parity asymmetric structure with C+Si-like clustering in the
superdeformed band. We predict that C+Si molecular bands may be
built above the superdeformed band due to the excitation of inter-cluster
motion. They are considered to be higher nodal states of the superdeformed
state. We also suggest negative-parity bands caused by the parity asymmetric
deformation.Comment: 13 figures, submitted to Phys. Rev.
FORMALDEHYDE FOR THE PREMIXED COMPRESSION-IGNITION ENGINE -AN ADDITIVE FOR IGNITION-TIMING CONTROL
Abstract Lean fuel/air mixtures with various fuel/fuel ratios betwee
Alpha clustering and weak coupling in the A=90 region
From the viewpoint of a unified description of cluster structure and
scattering in the
A=90 region, scattering from Y is investigated.
clustering and weak coupling in Nb is discussed.Comment: 8 pages, 4 figure
Deformed Base Antisymmetrized Molecular Dynamics and its Application to ^{20}Ne
A new theoretical framework named as deformed base antisymmetrized molecular
dynamics that uses the localized triaxially deformed Gaussian as the single
particle wave packet is presented. The model space enables us to describe
sufficiently well the deformed mean-field structure as well as the cluster
structure and their mixed structure within the same framework. The improvement
over the original version of the antisymmetrized molecular dynamics which uses
the spherical Gaussian is verified by the application to
nucleus. The almost pure cluster structure of the
= band, the distortion of the cluster structure in the
= band and the dominance of the deformed mean-field structure of
the = band are confirmed and their observed properties are
reproduced. Especially, the intra-band E2 transition probabilities in
= and bands are reproduced without any effective charge.
Since it has been long known that the pure
cluster model underestimates the intra-band transitions in the
= band by about 30%, we consider that this success is due to the
sufficient description of the deformed mean-field structure in addition to the
cluster structure by the present framework. From the successful description of
, we expect that the present framework presents us with a
powerful approach for the study of the coexistence and interplay of the
mean-field structure and the cluster structure
Roles of proton-neutron interactions in alpha-like four-nucleon correlations
An extended pairing plus QQ force model, which has been shown to successfully
explain the nuclear binding energy and related quantities such as the symmetry
energy, is applied to study the alpha-like four-nucleon correlations in
1f_{7/2} shell nuclei.
The double difference of binding energies, which displays a characteristic
behavior at , is interpreted in terms of the alpha-like
correlations. Important roles of proton-neutron interactions forming the
alpha-like correlated structure are discussed.Comment: 10 pages, 2 figures, RevTex, submitted to Phys. Rev.
Parity Violation in a Single Domain of Spin-Triplet Sr2RuO4 Superconductors
We observed an unconventional parity-violating vortex in single domain
Sr2RuO4 single crystals using a transport measurement. The current-voltage
characteristics of submicron Sr2RuO4 shows that the induced voltage has
anomalous components which are even function of the bias current. The results
may suggest that the vortex itself has a helical internal structure
characterized by a Hopf invariant (a topological invariant). We also discuss
that the hydrodynamics of such a helical vortex causes the parity violation to
retain the topological invariant.Comment: Accepted for publication in Solid State Communication
H- Beam Acceleration Test and Extraction Orbit Study at the CYRIC 680-Cyclotron
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-particle condensate states in O
The existence of a rotational band with the +C()
cluster structure, in which three particles in C() are
locally condensed, is demonstrated near the four- threshold of O
in agreement with experiment. This is achieved by studying structure and
scattering for the +C() system in a unified way. A
drastic reduction (quenching) of the moment of the inertia of the state
at 15.1 MeV just above the four- threshold in O suggests that it
could be a candidate for the superfluid state in -particle
condensation.Comment: 5 pages, 3 figure
Nuclear Alpha-Particle Condensates
The -particle condensate in nuclei is a novel state described by a
product state of 's, all with their c.o.m. in the lowest 0S orbit. We
demonstrate that a typical -particle condensate is the Hoyle state
( MeV, state in C), which plays a crucial role for
the synthesis of C in the universe. The influence of antisymmentrization
in the Hoyle state on the bosonic character of the particle is
discussed in detail. It is shown to be weak. The bosonic aspects in the Hoyle
state, therefore, are predominant. It is conjectured that -particle
condensate states also exist in heavier nuclei, like O,
Ne, etc. For instance the state of O at MeV
is identified from a theoretical analysis as being a strong candidate of a
condensate. The calculated small width (34 keV) of ,
consistent with data, lends credit to the existence of heavier Hoyle-analogue
states. In non-self-conjugated nuclei such as B and C, we discuss
candidates for the product states of clusters, composed of 's,
triton's, and neutrons etc. The relationship of -particle condensation
in finite nuclei to quartetting in symmetric nuclear matter is investigated
with the help of an in-medium modified four-nucleon equation. A nonlinear order
parameter equation for quartet condensation is derived and solved for
particle condensation in infinite nuclear matter. The strong qualitative
difference with the pairing case is pointed out.Comment: 71 pages, 41 figures, review article, to be published in "Cluster in
Nuclei (Lecture Notes in Physics) - Vol.2 -", ed. by C. Beck,
(Springer-Verlag, Berlin, 2011
Mature seed-derived callus of the model indica rice variety Kasalath is highly competent in Agrobacterium-mediated transformation
We previously established an efficient Agrobacterium-mediated transformation system using primary calli derived from mature seeds of the model japonica rice variety Nipponbare. We expected that the shortened tissue culture period would reduce callus browningâa common problem with the indica transformation system during prolonged tissue culture in the undifferentiated state. In this study, we successfully applied our efficient transformation system to Kasalathâa model variety of indica rice. The Luc reporter system is sensitive enough to allow quantitative analysis of the competency of rice callus for Agrobacterium-mediated transformation. We unexpectedly discovered that primary callus of Kasalath exhibits a remarkably high competency for Agrobacterium-mediated transformation compared to Nipponbare. Southern blot analysis and Luc luminescence showed that independent transformation events in primary callus of Kasalath occurred successfully at ca. tenfold higher frequency than in Nipponbare, and single copy T-DNA integration was observed in ~40% of these events. We also compared the competency of secondary callus of Nipponbare and Kasalath and again found superior competency in Kasalath, although the identification and subsequent observation of independent transformation events in secondary callus is difficult due to the vigorous growth of both transformed and non-transformed cells. An efficient transformation system in Kasalath could facilitate the identification of QTL genes, since many QTL genes are analyzed in a Nipponbare Ă Kasalath genetic background. The higher transformation competency of Kasalath could be a useful trait in the establishment of highly efficient systems involving new transformation technologies such as gene targeting
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