A deformed QRPA formalism for single and two-neutrino double beta decay

We use a deformed QRPA formalism to describe simultaneously the energy distributions of the single beta Gamow-Teller strength and the two-neutrino double beta decay matrix elements. Calculations are performed in a series of double beta decay partners with A = 48, 76, 82, 96, 100, 116, 128, 130, 136 and 150, using deformed Woods-Saxon potentials and deformed Skyrme Hartree-Fock mean fields. The formalism includes a quasiparticle deformed basis and residual spin-isospin forces in the particle-hole and particle-particle channels. We discuss the sensitivity of the parent and daughter Gamow-Teller strength distributions in single beta decay, as well as the sensitivity of the double beta decay matrix elements to the deformed mean field and to the residual interactions. Nuclear deformation is found to be a mechanism of suppression of the two-neutrino double beta decay. The double beta decay matrix elements are found to have maximum values for about equal deformations of parent and daughter nuclei. They decrease rapidly when differences in deformations increase. We remark the importance of a proper simultaneous description of both double beta decay and single Gamow-Teller strength distributions. Finally, we conclude that for further progress in the field it would be useful to improve and complete the experimental information on the studied Gamow-Teller strengths and nuclear deformations.Comment: 33 pages, 19 figures. To be published in Phys. Rev.

Precise measurements of electron and hole g-factors of single quantum dots by using nuclear field

We demonstrated the cancellation of the external magnetic field by the nuclear field at one edge of the nuclear polarization bistability in single InAlAs quantum dots. The cancellation for the electron Zeeman splitting gives the precise value of the hole g-factor. By combining with the exciton g-factor that is obtained from the Zeeman splitting for linearly polarized excitation, the magnitude and sign of the electron and hole g-factors in the growth direction are evaluated.Comment: 3 pages, 2 figure

Effect of doping and oxygen vacancies on the octahedral tilt transitions in the BaCeO3 perovskite

We present a systematic study of the effect of Y doping and hydration level on the structural transformations of BaCeO3 based on anelastic spectroscopy experiments. The temperature of the intermediate transformation between rhombohedral and orthorhombic Imma phases rises with increasing the molar fraction x of Y roughly as (500 K)x in the hydrated state, and is depressed of more than twice that amount after complete dehydration. This is explained in terms of the effect of doping on the average (Ce/Y)-O and Ba-O bond lengths, and of lattice relaxation from O vacancies. The different behavior of the transition to the lower temperature Pnma orthorhombic phase is tentatively explained in terms of progressive flattening of the effective shape of the OH ion and ordering of the O vacancies during cooling.Comment: 8 pages, 5 figure

Low-Temperature Magnetoresistance in Magnesium and Aluminum Containing Small Concentrations of Manganese or Iron

Magnetoresistance measurements in magnetic fileds up to 21 kOe have been made on Mg-Mn, Mg-Cd, Mg-Al, Al-Mn, and Al-Fe alloys in the temperature region of liquid helium. Magnesium alloys containing more than 0.1-at.% Mn which exhibit a resistance maximum and minimum in zero filed, show a negative magnetoresistance, whereas the more dilute samples (0.001-0.1 at. % Mn) show a positive magnetoresistance, the magnitude of which decreases with decreasing temperature. The magnesium alloys containing non-transition element impurities, as well as the aluminum alloys containing transition metal impurities, are found to obey Kohler\u27s rule. From an analysis of these data it is found that the magnetoresistivity of a dilute alloy of magnesium containing manganese, can be considered as the sum of a normal positive magnetoresistivity (obeying Kohler\u27s rule) and an anomalous term which is negative in sign, does not obey Kohler\u27s rule and is presumably due to a magnetic scattering of the conduction electrons. Using values of thes s-d exchange integral and the Coulomb scattering integral derived from an analysis of the zero-field resistivity permits an explanation of the magnetoresistivity based on Kasuya\u27s theory, at temperatures near the Neel point

Double Beta Decay in pn-QRPA Model with Isospin and SU(4) Symmetry Constraints

The transition matrix elements for the $0^{+}\to 0^{+}$ double beta decays are calculated for $^{48}Ca$, $^{76}Ge$, $^{82}Se$, $^{100}Mo$, $^{128}Te$ and $^{130}Te$ nuclei, using a ${\delta}$-interaction. As a guide, to fix the particle-particle interaction strengths, we exploit the fact that the missing symmetries of the mean field approximation are restored in the random phase approximation by the residual interaction. Thus, the T=1, S=0 and T=0, S=1 coupling strengths have been estimated by invoking the partial restoration of the isospin and Wigner SU(4) symmetries, respectively. When this recipe is strictly applied, the calculation is consistent with the experimental limit for the $2\nu$ lifetime of $^{48}Ca$ and it also correctly reproduces the $2\nu$ lifetime of $^{82}Se$. In this way, however, the two-neutrino matrix elements for the remaining nuclei are either underestimated (for $^{76}Ge$ and $^{100}Mo$) or overestimated (for $^{128}Te$ and $^{130}Te$) approximately by a factor of 3. With a comparatively small variation ($<10$) of the spin-triplet parameter, near the value suggested by the SU(4) symmetry, it is possible to reproduce the measured $T_{1/2}^{2\nu}$ in all the cases. The upper limit for the effective neutrino mass, as obtained from the theoretical estimates of $0\nu$ matrix elements, is $\cong 1$ eV. The dependence of the nuclear matrix elements on the size of the configuration space has been also analyzed.Comment: 25 pages (LaTex) and 3 figures upon request, to be published in Nucl. Phys.

Informed consent in clinical trials using stem cells: Suggestions and points of attention from informed consent training workshops in Japan

Informed consent (IC) is an essential requirement of ethical research involving human participants, and is usually achieved by providing prospective research participants (PRPs) with a document that explains the study and its procedures. However, results of a series of IC workshops held in Tokyo during 2014 indicate that consent forms alone are not enough to achieve full IC in regenerative medicine research, due to the necessity of long-term patient-safety observations to meet the ethical challenges of such research. Adequate training of the people who are responsible for obtaining IC (elucidators) is also necessary to ensure full IC. Elucidators must be able to provide PRPs with sufficient information to ensure adequate comprehension of the study and its potential after-effects; judge PRPs’ voluntariness and eligibility; and establish and/or maintain partnerships with PRPs. The workshops used role-playing simulations, to demonstrate how to effectively obtain fuller IC, to members of several Japanese research groups preparing for clinical stem cell trials. Workshop results were correlated with the results of a 2013 workshop on what information patients want when considering participation in induced pluripotent stem cell (iPSC) research. The correlated results showed the need for continuous training and education of elucidators in order to make sure that they acquire and maintain IC competency

The Pauli principle, QRPA and the two-neutrino double beta decay

We examine the violation of the Pauli exclusion principle in the Quasiparticle Random Phase Approximation (QRPA) calculation of the two-neutrino double beta decay matrix elements, which has its origin in the quasi-boson approximation. For that purpose we propose a new renormalized QRPA with proton-neutron pairing method (full-RQRPA) for nuclear structure studies, which includes ground state correlation beyond the QRPA. This is achieved by using of renormalized quasi-boson approximation, in which the Pauli exclusion principle is taken into account more carefully. The full-RQRPA has been applied to two-neutrino double beta decay of $^{76}Ge$, $^{82}Se$, $^{128}Te$ and $^{130}Te$. The nuclear matrix elements have been found significantly less sensitive to the increasing strength of particle-particle interaction in the physically interesting region in comparison with QRPA results. The strong differences between the results of both methods indicate that the Pauli exclusion principle plays an important role in the evaluation of the double beta decay. The inclusion of the Pauli principle removes the difficulties with the strong dependence on the particle-particle strength $g_{pp}$ in the QRPA on the two-neutrino double beta decay.Comment: Accepted for publication in Nucl. Phys. A, 22 pages, including 5 figures, LaTeX (using REVTeX and epsfig-style

Spinal vascular lesions: anatomy, imaging techniques and treatment

Vascular lesions of the spinal cord are rare but potentially devastating conditions whose accurate recognition critically determines the clinical outcome. Several conditions lead to myelopathy due to either arterial ischemia, venous congestion or bleeding within the cord. The clinical presentation varies, according with the different aetiology and mechanism of damage

Shell Model Study of the Double Beta Decays of 76^{76}Ge, 82^{82}Se and 136^{136}Xe

The lifetimes for the double beta decays of $^{76}$Ge, $^{82}$Se and $^{136}$Xe are calculated using very large shell model spaces. The two neutrino matrix elements obtained are in good agreement with the present experimental data. For $<1$ eV we predict the following upper bounds to the half-lives for the neutrinoless mode: $T^{(0\nu)}_{1/2}(Ge) > 1.85\,10^{25} yr.$, $T^{(0\nu)}_{1/2}(Se) > 2.36\,10^{24} yr.$ and $T^{(0\nu)}_{1/2}(Xe) > 1.21\,10^{25} yr$. These results are the first from a new generation of Shell Model calculations reaching O(10$^{8}$) dimensions