2,648 research outputs found
Relativistic Harmonic Oscillator with Spin Symmetry
The eigenfunctions and eigenenergies for a Dirac Hamiltonian with equal
scalar and vector harmonic oscillator potentials are derived. Equal scalar and
vector potentials may be applicable to the spectrum of an antinucleion imbedded
in a nucleus. Triaxial, axially deformed, and spherical oscillator potentials
are considered. The spectrum has a spin symmetry for all cases and, for the
spherical harmonic oscillator potential, a higher symmetry analogous to the
SU(3) symmetry of the non-relativistic harmonic oscillator is discussed
Chromosomal Gains and Losses in Uveal Melanomas Detected by Comparative Genomic Hybridization
Eleven uveal melanomas were analyzed using comparative genomic hybridization (CGH). The most abundant genetic changes were loss of chromosome 3, overrepresentation of 6p, loss of 6q, and multiplication of 8q. The smallest overrepresented regions on 6p and 8q were 6pterp21 and 8q24qter, respectively. Several additional gains and losses of chromosome segments were repeatedly observed, the most frequent one being loss of 9p (three cases). Monosomy 3 appeared to be a marker for ciliary body involvement.
CGH data were compared with the results of chromosome banding. Some alterations, e.g., gains of 6p and losses of 6q, were observed with higher frequencies after CGH, while others, e.g., 9p deletions, were detected only by CGH. The data suggest some similarities of cytogenetic alterations between cutaneous and uveal melanoma. In particular, the 9p deletions are of interest due to recent reports about the location of a putative tumor-suppressor gene for cutaneous malignant melanoma in this region
Equilibration in the time-dependent Hartree-Fock approach probed with the Wigner distribution function
Calculating the Wigner distribution function in the reaction plane, we are
able to probe the phase-space behavior in time-dependent Hartree-Fock during a
heavy-ion collision. We compare the Wigner distribution function with the
smoothed Husimi distribution function. Observables are defined to give a
quantitative measure for local and global equilibration. We present different
reaction scenarios by analyzing central and non-central and
collisions. It is shown that the initial phase-space
volumes of the fragments barely merge. The mean values of the observables are
conserved in fusion reactions and indicate a "memory effect" in time-dependent
Hartree-Fock. We observe strong dissipation but no evidence for complete
equilibration.Comment: 12 pages, 10 figure
Orbital magnetism in axially deformed sodium clusters: From scissors mode to dia-para magnetic anisotropy
Low-energy orbital magnetic dipole excitations, known as scissors mode (SM),
are studied in alkali metal clusters. Subsequent dynamic and static effects are
explored. The treatment is based on a self-consistent microscopic approach
using the jellium approximation for the ionic background and the Kohn-Sham mean
field for the electrons. The microscopic origin of SM and its main features
(structure of the mode in light and medium clusters, separation into low- and
high-energy plasmons, coupling high-energy M1 scissors and E2 quadrupole
plasmons, contributions of shape isomers, etc) are discussed. The scissors M1
strength acquires large values with increasing cluster size. The mode is
responsible for the van Vleck paramagnetism of spin-saturated clusters. Quantum
shell effects induce a fragile interplay between Langevin diamagnetism and van
Vleck paramagnetism and lead to a remarkable dia-para anisotropy in magnetic
susceptibility of particular light clusters. Finally, several routes for
observing the SM experimentally are discussed.Comment: 21 pages, 7 figure
Decay Rate of Triaxially-Deformed Proton Emitters
The decay rate of a triaxially-deformed proton emitter is calculated in a
particle-rotor model, which is based on a deformed Woods-Saxon potential and
includes a deformed spin-orbit interaction. The wave function of the
ground state of the deformed proton emitter Ho is obtained
in the adiabatic limit, and a Green's function technique is used to calculate
the decay rate and branching ratio to the first excited 2 state of the
daughter nucleus. Only for values of the triaxial angle
is good agreement obtained for both the total decay rate and the 2
branching ratio.Comment: 19 pages, 4 figure
Peranan Staf Sekretariat Dewan dalam Menunjang Fungsi Dewan Perwakilan Rakyat Daerah Kota Tomohon1
Lembaga DPRD (Dewan Perwakilan Rakyat Daerah) dalam melaksanakan tugastugasnya,tidak mungkin dapat menyelesaikan dan membagi tugas dan melaksanakan seluruhaktivitas dalam organisasi tersebut tanpa bantuan orang lain, dalam hal ini turut membantumenyelesaikan dan memilah tugas yang akan dikerjakan adalah staf.Dalam membantu dan mengerjakan tugas Dewan Perwakilan Rakyat Daerah, adalahstaf yang merupakan unsur pelayanan terhadap Dewan Perwakilan Rakyat Daerah. Didalamsistem pemerintahan di Daerah, dikenal dengan adanya pemerintah yang terdiri dari KepalaDaerah dan Dewan Perwakilan Rakyat Daerah yang merupakan mitra kerja dalam rangkapenyelenggaraan pemerintahan di daerah. Dalam pelaksanaan otonomi daerah dikenal denganadanya azas desentralisasi, dekonsentrasi dan asas tugas pembantuan sebagai prinsip yangdianut. Ada sebagian tugas pemerintah pusat yang dilaksanakan oleh daerah dan ada yang jugadiselenggarakan dan tetap menjadi tugas pemerintah pusat.Dalam penelitian mengkaji tentang bagaimana peran staf sekretaira DPRD dalammenunjang fungsi anggota dewa yakni Fungsi Legislasi, Budgeting dan Controling. Denganmenggunakan metode penelitian kualitatif agar dapat menggambarkan lebih jelas bagaimanaperan staf. Dari hasil penelitian dapat dilihat bahwa disiplin pegawai masih harus ditingkatkan
Soliton binding and low-lying singlets in frustrated odd-legged S=1/2 spin tubes
Motivated by the intriguing properties of the vanadium spin tube Na2V3O7, we
show that an effective spin-chirality model similar to that of standard
Heisenberg odd-legged S=1/2 spin tubes can be derived for frustrated inter-ring
couplings, but with a spin-chirality coupling constant alpha that can be
arbitrarily small. Using density matrix renormalization group and analytical
arguments, we show that, while spontaneous dimerization is always present,
solitons become bound into low-lying singlets as alpha is reduced. Experimental
implications for strongly frustrated tubes are discussed.Comment: 4 pages, 4 figure
Description of nuclear systems within the relativistic Hartree-Fock method with zero range self-interactions of the scalar field
An exact method is suggested to treat the nonlinear self-interactions (NLSI)
in the relativistic Hartree-Fock (RHF) approach for nuclear systems. We
consider here the NLSI constructed from the relativistic scalar nucleon
densities and including products of six and eight fermion fields. This type of
NLSI corresponds to the zero range limit of the standard cubic and quartic
self-interactions of the scalar field. The method to treat the NLSI uses the
Fierz transformation, which enables one to express the exchange (Fock)
components in terms of the direct (Hartree) ones. The method is applied to
nuclear matter and finite nuclei. It is shown that, in the RHF formalism, the
NLSI, which are explicitly isovector-independent, generate scalar, vector and
tensor nucleon self-energies strongly density-dependent. This strong isovector
structure of the self-energies is due to the exchange terms of the RHF method.
Calculations are carried out with a parametrization containing five free
parameters. The model allows a description of both types of systems compatible
with experimental data.Comment: 23 pages, 14 figures (v2: major quantitative changes
A new microscopic nucleon-nucleon interaction derived from relativistic mean field theory
A new microscopic nucleon-nucleon (NN) interaction has been derived for the
first time from the popular relativistic mean field theory (RMFT) Lagrangian.
The NN interaction so obtained remarkably relate to the inbuilt fundamental
parameters of RMFT. Furthermore, by folding it with the RMFT-densities of
cluster and daughter nuclei to obtain the optical potential, it's application
is also examined to study the exotic cluster radioactive decays, and results
obtained found comparable with the successfully used M3Y phenomenological
effective NN interactions. The presently derived NN-interaction can also be
used to calculate a number of other nuclear observables.Comment: 4 Pages 2 Figure
Measurement uncertainty relations
Measurement uncertainty relations are quantitative bounds on the errors in an
approximate joint measurement of two observables. They can be seen as a
generalization of the error/disturbance tradeoff first discussed heuristically
by Heisenberg. Here we prove such relations for the case of two canonically
conjugate observables like position and momentum, and establish a close
connection with the more familiar preparation uncertainty relations
constraining the sharpness of the distributions of the two observables in the
same state. Both sets of relations are generalized to means of order
rather than the usual quadratic means, and we show that the optimal constants
are the same for preparation and for measurement uncertainty. The constants are
determined numerically and compared with some bounds in the literature. In both
cases the near-saturation of the inequalities entails that the state (resp.
observable) is uniformly close to a minimizing one.Comment: This version 2 contains minor corrections and reformulation
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