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Control of the persistent currents in two interacting quantum rings through the Coulomb interaction and inter-ring tunneling

The persistent current in two vertically coupled quantum rings containing few electrons is studied. We find that the Coulomb interaction between the rings in the absence of tunneling affects the persistent current in each ring and the ground state configurations. Quantum tunneling between the rings alters significantly the ground state and the persistent current in the system.Comment: accepted for publication in Phys. Rev.

Linking Ultracold Polar Molecules

We predict that pairs of polar molecules can be weakly bound together in an ultracold environment, provided that a dc electric field is present. The field that links the molecules together also strongly influences the basic properties of the resulting dimer, such as its binding energy and predissociation lifetime. Because of their long-range character these dimers will be useful in disentangling cold collision dynamics of polar molecules. As an example, we estimate the microwave photoassociation yield for OH-OH cold collisions.Comment: 4 pages 2 figure

The Impact of Volunteer Experience on Adolescent Social Development: Evidence of Program Effects

The Social and Personal Responsibility Scale was employed in a study of the Youth Volunteers program, involving 44 adolescents in 12 projects, equally divided between child care and community service. Participants showed statistically significant gains on the Social Responsibility sub-scale. Girls gained more than boys and volunteers in community improvement projects gained more than those in child care. However, as in previous studies, gains were quite modest. Testimony from adolescents and adult participants was more strongly positive, volunteers citing improvement in their knowledge of themselves and others and the acquisition of new skills, adults seeing greater willingness to make decisions. Child care volunteers and their adult advisers said they gained competence in working with young children. The generalized impact of volunteer experience on enduring attitudes appears to be positive but small. Future studies should attend as well to differences in the nature of the experiences adolescent volunteers have and to effects that vary among participants

SP mountain data analysis

An analysis of synthetic aperture radar data of SP Mountain was undertaken to demonstrate the use of digital image processing techniques to aid in geologic interpretation of SAR data. These data were collected with the ERIM X- and L-band airborne SAR using like- and cross-polarizations. The resulting signal films were used to produce computer compatible tapes, from which four-channel imagery was generated. Slant range-to-ground range and range-azimuth-scale corrections were made in order to facilitate image registration; intensity corrections were also made. Manual interpretation of the imagery showed that L-band represented the geology of the area better than X-band. Several differences between the various images were also noted. Further digital analysis of the corrected data was done for enhancement purposes. This analysis included application of an MSS differencing routine and development of a routine for removal of relief displacement. It was found that accurate registration of the SAR channels is critical to the effectiveness of the differencing routine. Use of the relief displacement algorithm on the SP Mountain data demonstrated the feasibility of the technique

Power Spectrum Correlations Induced by Non-Linear Clustering

Gravitational clustering is an intrinsically non-linear process that generates significant non-Gaussian signatures in the density field. We consider how these affect power spectrum determinations from galaxy and weak-lensing surveys. Non-Gaussian effects not only increase the individual error bars compared to the Gaussian case but, most importantly, lead to non-trivial cross-correlations between different band-powers. We calculate the power-spectrum covariance matrix in non-linear perturbation theory (weakly non-linear regime), in the hierarchical model (strongly non-linear regime), and from numerical simulations in real and redshift space. We discuss the impact of these results on parameter estimation from power spectrum measurements and their dependence on the size of the survey and the choice of band-powers. We show that the non-Gaussian terms in the covariance matrix become dominant for scales smaller than the non-linear scale, depending somewhat on power normalization. Furthermore, we find that cross-correlations mostly deteriorate the determination of the amplitude of a rescaled power spectrum, whereas its shape is less affected. In weak lensing surveys the projection tends to reduce the importance of non-Gaussian effects. Even so, for background galaxies at redshift z=1, the non-Gaussian contribution rises significantly around l=1000, and could become comparable to the Gaussian terms depending upon the power spectrum normalization and cosmology. The projection has another interesting effect: the ratio between non-Gaussian and Gaussian contributions saturates and can even decrease at small enough angular scales if the power spectrum of the 3D field falls faster than 1/k^2.Comment: 34 pages, 15 figures. Revised version, includes a clearer explanation of why the hierarchical ansatz does not provide a good model of the covariance matrix in the non-linear regime, and new constraints on the amplitudes Ra and Rb for general 4-pt function configurations in the non-linear regim

Artificial molecular quantum rings: Spin density functional theory calculations

The ground states of artificial molecules made of two vertically coupled quantum rings are studied within the spin density functional theory for systems containing up to 13 electrons. Quantum tunneling effects on the electronic structure of the coupled rings are analyzed. For small ring radius, our results recover those of coupled quantum dots. For intermediate and large ring radius, new phases are found showing the formation of new diatomic artificial ring molecules. Our results also show that the tunneling induced phase transitions in the coupled rings occur at much smaller tunneling energy as compared to those for coupled quantum dot systems.Comment: 10 pages, 6 figure

Switching treatments in clinically stable relapsing remitting multiple sclerosis patients planning for pregnancy

Background: The decision to have children can be complex, particularly for people with multiple sclerosis (MS). A key concern is the use of disease modifying drugs (DMDs) during pregnancy, and how continuing, stopping or switching them may affect the mother and child. In people with active MS, stopping medications puts the mother at risk of relapse and disease rebound. Objectives: Review evidence on the effect of different switching strategies in people with stable relapsing remitting MS (RRMS). Methods: We searched MEDLINE, EMBASE, EMCARE, CINAHL, SCOPUS, Cochrane Library up to March 2020. Only papers in English were included and no other limits were applied. Seven articles were included: four cohorts, two case reports and one randomized controlled trial (RCT). Results: Two strategies were found: de-escalating, which was associated with an increased risk of relapses, and switching between first line injectables, with no change in relapse rate observed. Conclusion: Evidence on the effect of switching strategy on disease course in stable RRMS patients planning for pregnancy is scarce, but when switching, current evidence suggests the risk of relapses mirrors known medication efficacy