Simply connected minimal symplectic 4-manifolds with signature less than - 1

For each pair (e,σ) of integers satisfying 2e + 3σ ≥ 0, σ ≤ - 2, and e + σ ≡0 (mod 4), with four exceptions, we construct a minimal, simply connected symplectic 4-manifold with Euler characteristic e and signature σ. We also produce simply connected, minimal symplectic 4-manifolds with signature zero (resp. signature-1) with Euler characteristic 4k (resp. 4k + 1) for all k ≥ 46 (resp. k ≥ 49). © European Mathematical Society 2010

Thrombotic risk assessment in antiphospholipid syndrome: do noncriteria antibodies contribute?

BACKGROUND/AIM: In this cross-sectional study, it was aimed to test the predictive value of noncriteria antiphospholipid antibodies (aPL) in addition to the global antiphospholipid syndrome score (GAPSS) in predicting vascular thrombosis (VT) in a cohort of patients with APS and aPL (+) systemic lupus erythematosus (SLE). MATERIAL AND METHODS: This study included 50 patients with primary APS, 68 with SLE/APS, and 52 with aPL (+) SLE who were classified according to VT as VT ± pregnancy morbidity (PM), PM only or aPL (+) SLE. Antiphospholipid serology consisting of lupus anticoagulant (LA), anticardiolipin (aCL) immunoglobulin G (IgG)/IgM/IgA, antibeta2 glycoprotein I (aβ2GPI) IgG/IgM/IgA, antiphosphatidylserine/prothrombin (aPS/PT) IgG/IgM and antidomain-I (aDI) IgG was determined for each patient. The GAPSS and adjusted GAPSS (aGAPSS) were calculated for each patient, as previously defined. Logistic regression analysis was carried out with thrombosis as the dependent variable and high GAPSS, aCL IgA, aβ2GPI IgA, and aDI IgG as independent variables. RESULTS: The mean GAPSS and aGAPSS of the study population were 11.6 ± 4.4 and 9.6 ± 3.8. Both the VT ± PM APS (n = 105) and PM only APS (n = 13) groups had significantly higher GAPSS and aGAPSS values compared to the aPL (+) SLE (n = 52) group. The patients with recurrent thrombosis had higher aGAPSS but not GAPSS than those with a single thrombotic event. The computed area under the receiver operating characteristic curve demonstrated that a GAPSS ≥13 and aGAPSS ≥10 had the best predictive values for thrombosis. Logistic regression analysis including a GAPSS ≥13, aCL IgA, aβ2GPI IgA, and aDI IgG showed that none of the factors other than a GAPSS ≥13 could predict thrombosis. CONCLUSION: Both the GAPSS and aGAPSS successfully predict the thrombotic risk in aPL (+) patients and aCL IgA, aβ2GPI IgA, and aDI IgG do not contribute to high a GAPSS or aGAPSS

Spin Accumulation in Diffusive Conductors with Rashba and Dresselhaus Spin-Orbit Interaction

We calculate the electrically induced spin accumulation in diffusive systems due to both Rashba (with strength $\alpha)$ and Dresselhaus (with strength $\beta)$ spin-orbit interaction. Using a diffusion equation approach we find that magnetoelectric effects disappear and that there is thus no spin accumulation when both interactions have the same strength, $\alpha=\pm \beta$. In thermodynamically large systems, the finite spin accumulation predicted by Chaplik, Entin and Magarill, [Physica E {\bf 13}, 744 (2002)] and by Trushin and Schliemann [Phys. Rev. B {\bf 75}, 155323 (2007)] is recovered an infinitesimally small distance away from the singular point $\alpha=\pm \beta$. We show however that the singularity is broadened and that the suppression of spin accumulation becomes physically relevant (i) in finite-sized systems of size $L$, (ii) in the presence of a cubic Dresselhaus interaction of strength $\gamma$, or (iii) for finite frequency measurements. We obtain the parametric range over which the magnetoelectric effect is suppressed in these three instances as (i) $|\alpha|-|\beta| \lesssim 1/mL$, (ii)$|\alpha|-|\beta| \lesssim \gamma p_{\rm F}^2$, and (iii) |\alpha|-|\beta| \lesssiM \sqrt{\omega/m p_{\rm F}\ell} with $\ell$ the elastic mean free path and $p_{\rm F}$ the Fermi momentum. We attribute the absence of spin accumulation close to $\alpha=\pm \beta$ to the underlying U (1) symmetry. We illustrate and confirm our predictions numerically

Exact microscopic analysis of a thermal Brownian motor

We study a genuine Brownian motor by hard disk molecular dynamics and calculate analytically its properties, including its drift speed and thermal conductivity, from microscopic theory.Comment: 4 pages, 5 figure

Low-energy quasiparticle states near extended scatterers in d-wave superconductors and their connection with SUSY quantum mechanics

Low-energy quasiparticle states, arising from scattering by single-particle potentials in d-wave superconductors, are addressed. Via a natural extension of the Andreev approximation, the idea that sign-variations in the superconducting pair-potential lead to such states is extended beyond its original setting of boundary scattering to the broader context of scattering by general single-particle potentials, such as those due to impurities. The index-theoretic origin of these states is exhibited via a simple connection with Witten's supersymmetric quantum-mechanical model.Comment: 5 page

Probing d-wave pairing correlations in the pseudogap regime of the cuprate superconductors via low-energy states near impurities

The issue of probing the pseudogap regime of the cuprate superconductors, specifically with regard to the existence and nature of superconducting pairing correlations of d-wave symmetry, is explored theoretically. It is shown that if the d-wave correlations believed to describe the superconducting state persist into the pseudogap regime, but with pair-potential phase-fluctuations that destroy their long-range nature, then the low-energy quasiparticle states observed near extended impurities in the truly superconducting state should also persist as resonances in the pseudogap regime. The scattering of quasiparticles by these phase-fluctuations broadens what was (in the superconducting state) a sharp peak in the single-particle spectral function at low energy, as we demonstrate within the context of a simple model. This peak and its broadening is, in principle, accessible via scanning tunneling spectroscopy near extended impurities in the pseudogap regime. If so, such experiments would provide a probe of the extent to which d-wave superconducting correlations persist upon entering the pseudogap regime, thus providing a stringent diagnostic of the phase-fluctuation scenario.Comment: 8 pages, 2 figure

The views and experiences of fathers regarding their young child's intellectual and developmental disability diagnosis: Findings from a qualitative study

AIMS AND OBJECTIVES: To report the views and experiences of fathers following their child's diagnosis of an intellectual and developmental disability (IDD). BACKGROUND: There is a growing interest in understanding the experiences of fathers of children with IDD given the transformation of the structural change of fathers' roles within the family and wider society. DESIGN: A qualitative design was used to elicit the view and experiences of fathers. METHODS: A total of ten Irish fathers participated in face-to-face interviews. The data were thematically analysed. The COREQ guidelines for reporting qualitative studies were used in the development of this paper. RESULTS: The key themes that emerged were (a) the confirmation of the child's diagnosis (b) the impact of the diagnosis and (c) father's motivation to participate in disability research. CONCLUSIONS: This study informs and develops a further understanding of the international evidence base of fathers receiving a confirmation of a child's diagnosis of an intellectual and developmental disability, the impact of the diagnosis on fathers and their motivation to share their stories to add to the disability research. Health and social care practitioners have important contributions to make in meeting the needs of fathers. There are specific areas to consider in terms of practice, education and research that require further attention and development to ensure fathers' distinct needs regarding their child's diagnosis of IDD are known and responded to effectively. RELEVANCE TO CLINICAL PRACTICE: This study highlights that when the child's disability is confirmed, fathers experience a diverse range of mixed emotions. Health and social care practitioners including nurses need to be aware of the impact of the diagnosis upon fathers. There is scope to develop the knowledge, skills and confidence of health and social care practitioners regarding the experiences of fathers and how they can further support fathers and their families during the critical time of a disability disclosure