6,035 research outputs found
Phase operators, phase states and vector phase states for SU(3) and SU(2,1)
This paper focuses on phase operators, phase states and vector phase states
for the sl(3) Lie algebra. We introduce a one-parameter generalized oscillator
algebra A(k,2) which provides a unified scheme for dealing with su(3) (for k <
0), su(2,1) (for k > 0) and h(4) x h(4) (for k = 0) symmetries. Finite- and
infinite-dimensional representations of A(k,2) are constructed for k < 0 and k
> 0 or = 0, respectively. Phase operators associated with A(k,2) are defined
and temporally stable phase states (as well as vector phase states) are
constructed as eigenstates of these operators. Finally, we discuss a relation
between quantized phase states and a quadratic discrete Fourier transform and
show how to use these states for constructing mutually unbiased bases
Robustness of individual score methods against model misspecification in autoregressive panel models
Occupation probability of harmonic-oscillator quanta for microscopic cluster-model wave functions
We present a new and simple method of calculating the occupation probability
of the number of total harmonic-oscillator quanta for a microscopic
cluster-model wave function. Examples of applications are given to the recent
calculations including -model for He, -model for
Li, and -model for Be as well as the classical
calculations of -model for Li and -model
for C. The analysis is found to be useful for quantifying the amount of
excitations across the major shell as well as the degree of clustering. The
origin of the antistretching effect is discussed.Comment: 9 page
Observation of Brewster's effect for transverse-electric electromagnetic waves in metamaterials: Experiment and theory
We have experimentally realized Brewster's effect for transverse-electric
waves with metamaterials. In dielectric media, Brewster's no-reflection effect
arises only for transverse-magnetic waves. However, it has been theoretically
predicted that Brewster's effect arises for TE waves under the condition that
the relative permeability r is not equal to unity. We have designed an array of
split-ring resonators as a metamaterial with mu_r 1 using a finite-difference
time-domain method. The reflection measurements were carried out in a 3-GHz
region and the disappearance of reflected waves at a particular incident angle
was confirmed.Comment: 4 pages, 5 figure
Observing the Profile of an Atom Laser Beam
We report on an investigation of the beam profile of an atom laser extracted
from a magnetically trapped Rb Bose-Einstein condensate. The transverse
momentum distribution is magnified by a curved mirror for matter waves and a
momentum resolution of 1/60 of a photon recoil is obtained. We find the
transverse momentum distribution to be determined by the mean-field potential
of the residing condensate, which leads to a non-smooth transverse density
distribution. Our experimental data are compared with a full 3D simulation of
the output coupling process and we find good agreement.Comment: 4 pages, 4 figure
Vector coherent state theory of the generic representations of so(5) in an so(3) basis
For applications of group theory in quantum mechanics, one generally needs
explicit matrix representations of the spectrum generating algebras that arise
in bases that reduce the symmetry group of some Hamiltonian of interest. Here
we use vector coherent state techniques to develop an algorithm for
constructing the matrices for arbitrary finite-dimensional irreps of the SO(5)
Lie algebra in an SO(3) basis. The SO(3) subgroup of SO(5) is defined by
regarding SO(5) as linear transformations of the five-dimensional space of an
SO(3) irrep of angular momentum two. A need for such irreps arises in the
nuclear collective model of quadrupole vibrations and rotations. The algorithm
has been implemented in MAPLE, and some tables of results are presented.Comment: 20 pages, uses multirow.sty, submitted to J. Math. Phy
Mass and Spin of Poincare Gauge Theory
We discuss two expressions for the conserved quantities (energy momentum and
angular momentum) of the Poincar\'e Gauge Theory. We show, that the variations
of the Hamiltonians, of which the expressions are the respective boundary
terms, are well defined, if we choose an appropriate phase space for asymptotic
flat gravitating systems. Furthermore, we compare the expressions with others,
known from the literature.Comment: 16 pages, plain-tex; to be published in Gen. Rel. Gra
Quantification of Plasma and Urine Thymidine and 2'-Deoxyuridine by LC-MS/MS for the Pharmacodynamic Evaluation of Erythrocyte Encapsulated Thymidine Phosphorylase in Patients with Mitochondrial Neurogastrointestinal Encephalomyopathy.
Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an ultra-rare disorder caused by mutations in TYMP, leading to a deficiency in thymidine phosphorylase and a subsequent systemic accumulation of thymidine and 2'-deoxyuridine. Erythrocyte-encapsulated thymidine phosphorylase (EE-TP) is under clinical development as an enzyme replacement therapy for MNGIE. Bioanalytical methods were developed according to regulatory guidelines for the quantification of thymidine and 2'-deoxyuridine in plasma and urine using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for supporting the pharmacodynamic evaluation of EE-TP. Samples were deproteinized with 5% perchloric acid (v/v) and the supernatants analyzed using a Hypercarb column (30 × 2.1 mm, 3 µm), with mobile phases of 0.1% formic acid in methanol and 0.1% formic acid in deionized water. Detection was conducted using an ion-spray interface running in positive mode. Isotopically labelled thymidine and 2'-deoxyuridine were used as internal standards. Calibration curves for both metabolites showed linearity (r > 0.99) in the concentration ranges of 10-10,000 ng/mL for plasma, and 1-50 µg/mL for urine, with method analytical performances within the acceptable criteria for quality control samples. The plasma method was successfully applied to the diagnosis of two patients with MNGIE and the quantification of plasma metabolites in three patients treated with EE-TP
Neutron-Proton Correlations in an Exactly Solvable Model
We examine isovector and isoscalar neutron-proton correlations in an exactly
solvable model based on the algebra SO(8). We look particularly closely at
Gamow-Teller strength and double beta decay, both to isolate the effects of the
two kinds of pairing and to test two approximation schemes: the renormalized
neutron-proton QRPA (RQRPA) and generalized BCS theory. When isoscalar pairing
correlations become strong enough a phase transition occurs and the dependence
of the Gamow-Teller beta+ strength on isospin changes in a dramatic and
unfamiliar way, actually increasing as neutrons are added to an N=Z core.
Renormalization eliminates the well-known instabilities that plague the QRPA as
the phase transition is approached, but only by unnaturally suppressing the
isoscalar correlations. Generalized BCS theory, on the other hand, reproduces
the Gamow-Teller strength more accurately in the isoscalar phase than in the
usual isovector phase, even though its predictions for energies are equally
good everywhere. It also mixes T=0 and T=1 pairing, but only on the isoscalar
side of the phase transition.Comment: 13 pages + 11 postscript figures, in RevTe
- …