997 research outputs found
The Pauli principle in a three-body cluster model and the momentum distributions after fragmentation of 6He and 11Li
We investigate two simple prescriptions to account for the Pauli principle in
a three-body cluster model employing a new method based on an adiabatic
hyperspherical expansion to solve the Faddeev equations in coordinate space.
The resulting wave functions are computed and compared. They are furthermore
tested on halo nuclei by calculations of momentum distributions and invariant
mass spectra arising after fragmentation of fast He and Li in
collisions with light targets. The prescriptions are very accurate and the
available measured quantities are remarkably well reproduced when final state
interactions are included.Comment: 18 pages, LaTex file, 15 postscript figures included using epsf.st
Study of the radiation hardness of CsI(Tl) scintillation crystals
This paper is devoted to the study of a degradation of CsI(Tl)crystals
scintillation characteristics under irradiation with gamma-quanta at the
uniformly distributed absorbed dose up to 3700 rad. The sample set consisted of
25 crystals of 30 cm long having a truncated pyramid shape and 30 rectangular
crystals of the same length. A large difference in the light output
deterioration caused by the radiation was observed for the samples of the same
shape. A substantial dependence of the average light output loss from the
sample shape is seen as well. On the other hand, the crystals from the same
ingot behave very similarly under irradiation
Theory of Transition Temperature of Magnetic Double Perovskites
We formulate a theory of double perovskite coumpounds such as SrFeReO
and SrFeMoO which have attracted recent attention for their possible
uses as spin valves and sources of spin polarized electrons. We solve the
theory in the dynamical mean field approximation to find the magnetic
transition temperature . We find that is determined by a subtle
interplay between carrier density and the Fe-Mo/Re site energy difference, and
that the non-Fe same-sublattice hopping acts to reduce . Our results
suggest that presently existing materials do not optimize
Ab-initio study of disorder effects on the electronic and magnetic structures of SrFeMoO
We have investigated the electronic structure of ordered and disordered
SrFeMoO using {\it ab-initio} band structure methods. The effect of
disorder was simulated within super-cell calculations to realize several
configurations with mis-site disorders. It is found that such disorder effects
destroy the half-metallic ferro-magnetic state of the ordered compound. It also
leads to a substantial reduction of the magnetic moments at the Fe sites in the
disordered configurations. Most interestingly, it is found for the disordered
configurations, that the magnetic coupling within the Fe sub-lattice as well as
that within the Mo sub-lattice always remain ferro-magnetic, while the two
sub-lattices couple anti-ferromagnetically, in close analogy to the magnetic
structure of the ordered compound, but in contrast to recent suggestions.Comment: 7 pages, 3 figure
Cross sections for Coulomb and nuclear breakup of three-body halo nuclei
All possible dissociation cross sections for the loosely bound three-body
halo nuclei He (n+n+) and Li (n+n+Li) are computed as
functions of target and beam energy. Both Coulomb and nuclear interactions are
included in the same theoretical framework. The measurements agree with the
calculations for energies above 100 Mev/nucleon. The largest cross sections
correspond to final states with zero or three particles for heavy and with two
neutrons for light targets.Comment: 5 pages, 3 figures, revte
Momentum distributions and reaction mechanisms for breakup of two--neutron halos
A theoretical model able to describe fragmentation reactions of three--body
halo nuclei on different targets, from light to heavy, is used to compute
neutron and core momentum distributions. Both Coulomb and nuclear interactions
are simultaneously included. We specify the different reaction mechanisms
related to various processes. The method is applied to fragmentation of He
and Li on C and Pb. We find good agreement with the available
experimental results.Comment: 10 pages, 3 figures, Phys.Lett.B in pres
Plastic Flow in Two-Dimensional Solids
A time-dependent Ginzburg-Landau model of plastic deformation in
two-dimensional solids is presented. The fundamental dynamic variables are the
displacement field \bi u and the lattice velocity {\bi v}=\p {\bi u}/\p t.
Damping is assumed to arise from the shear viscosity in the momentum equation.
The elastic energy density is a periodic function of the shear and tetragonal
strains, which enables formation of slips at large strains. In this work we
neglect defects such as vacancies, interstitials, or grain boundaries. The
simplest slip consists of two edge dislocations with opposite Burgers vectors.
The formation energy of a slip is minimized if its orientation is parallel or
perpendicular to the flow in simple shear deformation and if it makes angles of
with respect to the stretched direction in uniaxial stretching.
High-density dislocations produced in plastic flow do not disappear even if
the flow is stopped. Thus large applied strains give rise to metastable,
structurally disordered states. We divide the elastic energy into an elastic
part due to affine deformation and a defect part. The latter represents degree
of disorder and is nearly constant in plastic flow under cyclic straining.Comment: 16pages, Figures can be obtained at
http://stat.scphys.kyoto-u.ac.jp/index-e.htm
Exploring the Unitarity Triangle through CP violation observables in
We discuss the determination of the CKM parameters from the forthcoming
violation observables in decays. Combining the information on
mixing induced CP violation in , with the
precision observable and the -- mixing phase
, we propose a determination of the unitarity triangle . Computing the penguin parameters within QCD
factorization yield precise determination of , reflected
by a weak dependence on the which is shown as a second order effect.
The impact of the direct CP violation observable on the penguin
parameters are investigated and a lower bound on is extracted. We also
discuss the effect of the -- new physics mixing phase on
the penguin parameters and . Using the SU(3)-flavour
symmetry argument and the current -factories data provided by the modes, we complement the CP-violating
observables in a variety of ways, in particular we find that .
Finally we analyze systematically the SU(3)-symmetry breaking factor within QCD
factorization.Comment: 22 pages, 6 figures, typos corrected, reference and some remarks
adde
Comparing responsiveness of the EQ-5D-5L, EQ-5D-3L and EQ VAS in stroke patients
Aims: To date, evidence to support the construct validity of the EQ-5D-5L has primarily focused on cross-sectional data. The aims of this study were to examine the responsiveness of EQ-5D-5L in patients with stroke and to compare it with responsiveness of EQ-5D-3L and visual analogue scale (EQ VAS). Methods: We performed an observational longitudinal cohort study of patients with stroke. At 1Â week and 4Â months post-stroke, patients were assessed with modified Rankin Scale (mRS) and Barthel Index (BI)Â and were administered the EQ-5D-5L and EQ-5D-3L, including the EQ VAS. The EQ-5D-5L index scores were derived using the crosswalk methodology developed by the EuroQol Group. We classified patients according to two external criteria, based on mRS or BI, into 3 categories: âimprovement,â âstableâ or âdeteriorationâ. We assessed the responsiveness of each measure in each patient subgroup using: effect size (ES), standardized response mean (SRM), F-statistic, relative efficiency and area under the receiver operating characteristic curve. Results: A total of 112 patients (52Â % females; mean age 70.6Â years; 93Â % ischemic stroke) completed all the instruments at both occasions. In subjects with clinical improvement, EQ-5D-5L was consistently responsive, showing moderate ES (0.51â0.71) and moderate to large SRM (0.69â0.86). In general, EQ-5D-3L index appeared to be more responsive (ES 0.63â0.82; SRM 0.77â1.06) and EQ VAS less responsive (ES 0.51â0.65; SRM 0.59â0.69) than EQ-5D-5L index. Conclusions: The EQ-5D-5L index, based on the crosswalk value set, seems to be appropriately responsive in patients with stroke, 4Â months after disease onset. As far as EQ-5D-5L index is scored according to crosswalk approach, the EQ-5D-3L index appears to be more responsive in stroke population
Spontaneous CP Violating Phase as the Phase in PMNS Matrix
We study the possibility of identifying the CP violating phases in the PMNS
mixing matrix in the lepton sector and also that in the CKM mixing matrix in
the quark sector with the phase responsible for the spontaneous CP violation in
the Higgs potential, and some implications. Since the phase in the CKM mixing
matrix is determined by experimental data, the phase in the lepton sector is
therefore also fixed. The mass matrix for neutrinos is constrained leading to
constraints on the Jarlskog CP violating parameter , and the effective mass
for neutrinoless double beta decay. The Yukawa couplings are
also constrained. Different ways of identifying the phases have different
predictions for and . Future
experimental data can be used to distinguish different models.Comment: 16 pages, 3 figure
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