Decoupling Transition I. Flux Lattices in Pure Layered Superconductors

We study the decoupling transition of flux lattices in a layered superconductors at which the Josephson coupling J is renormalized to zero. We identify the order parameter and related correlations; the latter are shown to decay as a power law in the decoupled phase. Within 2nd order renormalization group we find that the transition is always continuous, in contrast with results of the self consistent harmonic approximation. The critical temperature for weak J is ~1/B, where B is the magnetic field, while for strong J it is~1/sqrt{B} and is strongly enhanced. We show that renormaliztion group can be used to evaluate the Josephson plasma frequency and find that for weak J it is~1/BT^2 in the decoupled phase.Comment: 14 pages, 5 figures. New sections III, V. Companion to following article on "Decoupling and Depinning II: Flux lattices in disordered layered superconductors

Strong contraction of the representations of the three dimensional Lie algebras

For any Inonu-Wigner contraction of a three dimensional Lie algebra we construct the corresponding contractions of representations. Our method is quite canonical in the sense that in all cases we deal with realizations of the representations on some spaces of functions; we contract the differential operators on those spaces along with the representation spaces themselves by taking certain pointwise limit of functions. We call such contractions strong contractions. We show that this pointwise limit gives rise to a direct limit space. Many of these contractions are new and in other examples we give a different proof

Ring-type singular solutions of the biharmonic nonlinear Schrodinger equation

We present new singular solutions of the biharmonic nonlinear Schrodinger equation in dimension d and nonlinearity exponent 2\sigma+1. These solutions collapse with the quasi self-similar ring profile, with ring width L(t) that vanishes at singularity, and radius proportional to L^\alpha, where \alpha=(4-\sigma)/(\sigma(d-1)). The blowup rate of these solutions is 1/(3+\alpha) for 4/d\le\sigma<4, and slightly faster than 1/4 for \sigma=4. These solutions are analogous to the ring-type solutions of the nonlinear Schrodinger equation.Comment: 21 pages, 13 figures, research articl

Scalable Task-Based Algorithm for Multiplication of Block-Rank-Sparse Matrices

A task-based formulation of Scalable Universal Matrix Multiplication Algorithm (SUMMA), a popular algorithm for matrix multiplication (MM), is applied to the multiplication of hierarchy-free, rank-structured matrices that appear in the domain of quantum chemistry (QC). The novel features of our formulation are: (1) concurrent scheduling of multiple SUMMA iterations, and (2) fine-grained task-based composition. These features make it tolerant of the load imbalance due to the irregular matrix structure and eliminate all artifactual sources of global synchronization.Scalability of iterative computation of square-root inverse of block-rank-sparse QC matrices is demonstrated; for full-rank (dense) matrices the performance of our SUMMA formulation usually exceeds that of the state-of-the-art dense MM implementations (ScaLAPACK and Cyclops Tensor Framework).Comment: 8 pages, 6 figures, accepted to IA3 2015. arXiv admin note: text overlap with arXiv:1504.0504

Velocity fluctuations of noisy reaction fronts propagating into a metastable state: testing theory in stochastic simulations

The position of a reaction front, propagating into a metastable state, fluctuates because of the shot noise of reactions and diffusion. A recent theory [B. Meerson, P.V. Sasorov, and Y. Kaplan, Phys. Rev. E 84, 011147 (2011)] gave a closed analytic expression for the front diffusion coefficient in the weak noise limit. Here we test this theory in stochastic simulations involving reacting and diffusing particles on a one-dimensional lattice. We also investigate a small noise-induced systematic shift of the front velocity compared to the prediction from the spatially continuous deterministic reaction-diffusion equation.Comment: 5 pages, 5 figure

Psychological interventions for caregivers of people with bipolar disorder: A systematic review and meta-analysis

AIMS: Clinical guidelines recommend psychological interventions be offered to caregivers of people with bipolar disorder. However, there is little clarity about the efficacy of such interventions. This review examined the efficacy of psychological interventions in improving caregiver-focused outcomes, including burden, psychological symptoms and knowledge. METHOD: A systematic search for controlled trials was conducted using a combination of electronic database searches (PsycINFO, MEDLINE, and CENTRAL), and hand searches. Risk of bias was assessed using the Cochrane Collaboration tool. Outcomes were meta-analysed using Review Manager (RevMan). RESULTS: Nine studies met inclusion criteria. All meta-analyses compared psychoeducation to a control. At post-treatment there was a large effect of psychoeducation on burden (g = -0.8, 95% CI: -1.32, -0.27). However, there was high heterogeneity, confidence intervals were wide, and the effect was not maintained at follow-up. The apparent effect of psychoeducation on psychological symptoms was driven by a single outlying study. There was a very large effect on knowledge at post-treatment (g = 2.60, 95% CI: 1.39, 3.82) and follow-up (g =2.41, 95% CI: 0.85, 3.98). LIMITATIONS: There was considerable diversity in study methodology and quality. The number of included studies and sample sizes were small. CONCLUSIONS: This review provides tentative meta-analytic evidence for the efficacy of psychoeducation in improving caregiver burden at post-treatment, and knowledge at post-treatment and follow-up. Services could consider offering psychoeducation as part of a multi-disciplinary package of care. However, more methodologically rigorous research is needed before clinical recommendations can be made with confidence

'Between a rock and a hard place': family members' experiences of supporting a relative with bipolar disorder

Purpose: Clinical guidelines emphasise the central role of family members in supporting people with bipolar disorder. However, there has been little focus on the challenges family members face in supporting their relative. This qualitative study explored the challenges of providing support to a relative with bipolar disorder, and how family members attempted to meet these challenges. Factors that helped or hindered their efforts were also explored, including experiences of professional support. Methods: Semi-structured interviews were conducted with 18 family members (partners, parents, adult children, and siblings). Transcripts were analysed using the Framework approach. Results: Participants faced numerous challenges pertaining to the nature of the disorder and specific illness phases, their relative’s responses to their attempts to help, and the limitations of support from healthcare professionals. Although participants were resourceful in managing these challenges, they strongly valued professional input. Six themes were identified: ‘Not knowing: like being in a minefield’, ‘It’s out of my control: sitting waiting for the next thing to happen’, ‘Treading on eggshells’, ‘Picking up on signs’, ‘Times of crisis: between a rock and a hard place’, and ‘I have to make my voice heard’. Conclusions: Family members supporting a relative with bipolar disorder face significant challenges but show considerable resourcefulness in managing them. The findings underline the importance of input from healthcare professionals to help family members effectively support their relative and manage the challenges they face. Professional support should be strengths-based, and tailored to family members’ needs

Spectral signatures of modulated d-wave superconducting phases

We calculate within a mean-field theory the spectral signatures of various striped d-wave superconducting phases. We consider both in-phase and anti-phase modulations of the superconducting order across a stripe boundary, and the effects of coexisting inhomogeneous orders, including spin stripes, charge stripes, and modulated d-density-wave. We find that the anti-phase modulated d-wave superconductor exhibits zero-energy spectral weight, primarily along extended arcs in momentum space. Concomitantly, a Fermi surface appears and typically includes both open segments and closed pockets. When weak homogeneous superconductivity is also present the Fermi surface collapses onto nodal points. Among them are the nodal points of the homogeneous d-wave superconductor, but others typically exist at positions which depend on the details of the modulation and the band structure. Upon increasing the amplitude of the constant component these additional points move towards the edges of the reduced Brillouin zone where they eventually disappear. The above signatures are also manifested in the density of states of the clean, and the disordered system. While the presence of coexisting orders changes some details of the spectral function, we find that the evolution of the Fermi-surface and the distribution of the low-energy spectral weight are largely unaffected by them.Comment: Published version. We added an appendix including the detailed Hamiltonians, and made other minor change