Competing electric and magnetic excitations in backward electron scattering from heavy deformed nuclei

Important $E2$ contributions to the $(e,e^{\prime})$ cross sections of low-lying orbital $M1$ excitations are found in heavy deformed nuclei, arising from the small energy separation between the two excitations with $I^{\pi}K = 2^+1$ and 1$^+1$, respectively. They are studied microscopically in QRPA using DWBA. The accompanying $E2$ response is negligible at small momentum transfer $q$ but contributes substantially to the cross sections measured at $\theta = 165 ^{\circ}$ for $0.6 < q_{\rm eff} < 0.9$ fm$^{-1}$ ($40 \le E_i \le 70$ MeV) and leads to a very good agreement with experiment. The electric response is of longitudinal $C2$ type for $\theta \le 175 ^{\circ}$ but becomes almost purely transverse $E2$ for larger backward angles. The transverse $E2$ response remains comparable with the $M1$ response for $q_{\rm eff} > 1.2$ fm$^{-1}$ ($E_i > 100$ MeV) and even dominant for $E_i > 200$ MeV. This happens even at large backward angles $\theta > 175 ^{\circ}$, where the $M1$ dominance is limited to the lower $q$ region.Comment: RevTeX, 19 pages, 8 figures included Accepted for publication in Phys Rev

Collective Excitations of (154)Sm nucleus at FEL{gamma}+LHC Collider

The production of collective excitations of the (154)Sm at FEL{gamma}+LHC collider is investigated. We show that this machine will be a powerful tool for investigation of high energy level excitations.Comment: 6 pages, 1 figure, 4 table

Thermal and electromagnetic properties of 166-Er and 167-Er

The primary gamma-ray spectra of 166-Er and 167-Er are deduced from the (3-He,alpha gamma) and (3-He,3-He' gamma) reaction, respectively, enabling a simultaneous extraction of the level density and the gamma-ray strength function. Entropy, temperature and heat capacity are deduced from the level density within the micro-canonical and the canonical ensemble, displaying signals of a phase-like transition from the pair-correlated ground state to an uncorrelated state at Tc=0.5 MeV. The gamma-ray strength function displays a bump around E-gamma=3 MeV, interpreted as the pygmy resonance.Comment: 21 pages including 2 tables and 11 figure

Association between rapidly progressive glomerulonephritis and the properdin factor BfF and different HLA-D region products

AbstractAssociation between rapidly progressive glomerulonephritis and the properdin factor BfF and different HLA-D region products. Frequencies of the HLA antigens ABC, DR and MT, as well as of the properdin factor alleles were determined in 24 unrelated patients presenting with immune complex mediated idiopathic rapidly progressive glomerulonephritis (RPGN) type II. As in Goodpasture syndrome (RPGN type I with pulmonary hemorrhage), a significant association with the B-cell alloantigen HLA-DR 2 was demonstrated (relative risk for HLA-DR 2 positive individuals was 3.54; P < 0.01). In addition a marked increase of the HLA specificity MT 3 was shown, which is supposed to belong to an antigen system of a second HLA-D region locus. The highest relative risk of 14.67 (P < 0.00001), however, was calculated for all patients carrying the BfF phenotype. Increased numbers of patients positive for HLA-DR 2 and -MT 3, as well as BfF suggested immune response genes or disease-related mutations on different haplotypes responsible for a MHC (major histocompatibility complex) associated predisposition of RPGN type II.Association entre la glomérulonéphrite rapidement progressive et le BfF du facteur de la properdine et les produits des différentes régions HLA-D. Les fréquences des antigènes HLA, ABC, DR et MT, ainsi que les allèles du facteur de la properdine ont été déterminées chez 24 malades non consanguins ayant une glomérulonéphrite rapidement progressive idiopathique médiée par des immunescomplexes (RPGN) de type IL Comme dans le syndrome de Goodpasture (RPGN de type I avec hémorragie pulmonaire), une association significative avec l'alloantigène cellulaire B HLA-DR 2 a été démontrée (le risque relatif pour des individus positifs à HLA-DR 2 était 3,54; P < 0,01). En plus, une augmentation marquée de la spécificité HLA-MT 3 a été montrée, laquelle est supposée appartenir à un système antigénique d'un second locus HLA-D. Le risque relatif le plus élevé, 14,67 (P < 0,00001), cependant, était calculé pour tous les malades porteurs du phénotype BfF. Les nombres augmentés de malades positifs pour HLA-DR 2 et-MT3, comme pour BfF suggéraient une réponse immune de gènes ou de mutations induites par la maladie sur différents haplotypes responsables d'une MHC (complexe principal d'histocompatibilité) associés à la prédisposition à une RPGN de type II

Orbital current mode in elliptical quantum dots

An orbital current mode peculiar to deformed quantum dots is theoretically investigated; first by using a simple model that allows to interpret analytically its main characteristics, and second, by numerically solving the microscopic equations of time evolution after an initial perturbation within the time-dependent local-spin-density approximation. Results for different deformations and sizes are shown.Comment: 4 REVTEX pages, 4 PDF figures, accepted in PRB:R

Level densities and γ\gamma-strength functions in 148,149^{148,149}Sm

The level densities and $\gamma$-strength functions of the weakly deformed $^{148}$Sm and $^{149}$Sm nuclei have been extracted. The temperature versus excitation energy curve, derived within the framework of the micro canonical ensemble, shows structures, which we associate with the break up of Cooper pairs. The nuclear heat capacity is deduced within the framework of both the micro canonical and the canonical ensemble. We observe negative heat capacity in the micro canonical ensemble whereas the canonical heat capacity exhibits an S-shape as function of temperature, both signals of a phase transition. The structures in the $\gamma$-strength functions are discussed in terms of the pygmy resonance and the scissors mode built on exited states. The samarium results are compared with data for the well deformed $^{161,162}$Dy, $^{166,167}$Er and $^{171,172}$Yb isotopes and with data from (n,$\gamma$)-experiments and giant dipole resonance studies.Comment: 12 figure

Temperature Dependence of Damping and Frequency Shifts of the Scissors Mode of a trapped Bose-Einstein Condensate

We have studied the properties of the scissors mode of a trapped Bose-Einstein condensate of $^{87}$Rb atoms at finite temperature. We measured a significant shift in the frequency of the mode below the hydrodynamic limit and a strong dependence of the damping rate as the temperature increased. We compared our damping rate results to recent theoretical calculations for other observed collective modes finding a fair agreement. From the frequency measurements we deduce the moment of inertia of the gas and show that it is quenched below the transition point, because of the superfluid nature of the condensed gas.Comment: 5 pages, 4 figure

Switchable Coupling of Vibrations to Two-Electron Carbon-Nanotube Quantum Dot States

We report transport measurements on a quantum dot in a partly suspended carbon nanotube. Electrostatic tuning allows us to modify and even switch 'on' and 'off' the coupling to the quantized stretching vibration across several charge states. The magnetic-field dependence indicates that only the two-electron spin-triplet excited state couples to the mechanical motion, indicating mechanical coupling to both the valley degree of freedom and the exchange interaction, in contrast to standard models

Gamma-ray strength function and pygmy resonance in rare earth nuclei

The gamma-ray strength function for gamma energies in the 1-7 MeV region has been measured for 161,162-Dy and 171,172-Yb using the (3-He,alpha gamma) reaction. Various models are tested against the observed gamma-ray strength functions. The best description is based on the Kadmenskii, Markushev and Furman E1 model with constant temperature and the Lorentzian M1 model. A gamma-ray bump observed at E_gamma=3 MeV is interpreted as the so-called pygmy resonance, which has also been observed previously in (n,gamma) experiments. The parameters for this resonance have been determined and compared to the available systematics.Comment: 11 pages, including 4 figures and 2 table