Non-BPS Solutions of the Noncommutative CP^1 Model in 2+1 Dimensions

We find non-BPS solutions of the noncommutative CP^1 model in 2+1 dimensions. These solutions correspond to soliton anti-soliton configurations. We show that the one-soliton one-anti-soliton solution is unstable when the distance between the soliton and the anti-soliton is small. We also construct time-dependent solutions and other types of solutions.Comment: 11 pages, minor correction

Noncommutative waves have infinite propagation speed

We prove the existence of global solutions to the Cauchy problem for noncommutative nonlinear wave equations in arbitrary even spatial dimensions where the noncommutativity is only in the spatial directions. We find that for existence there are no conditions on the degree of the nonlinearity provided the potential is positive. We furthermore prove that nonlinear noncommutative waves have infinite propagation speed, i.e., if the initial conditions at time 0 have a compact support then for any positive time the support of the solution can be arbitrarily large.Comment: 15 pages, references adde

high body mass index is associated with increased risk of implant dislocation following primary total hip replacement 2 106 patients followed for up to 8 years

Background and purpose Implant dislocation is one of the commonest complications following primary total hip replacement (THR). We investigated the effect of body mass index (BMI) and tobacco use on the risk of this complication.Subjects and methods Through linkage between the Swedish Construction Workers' cohort and the Swedish Inpatient Register, 2,106 male patients who had undergone primary THR between 1997 and 2004 were identified. We used Cox multivariable regression analysis to study the association between BMI and tobacco use and the risk of implant dislocation.Results 53 patients (2.5%) developed implant dislocation during a mean of 2 (0–3) years of follow-up. We found overweight and obesity to be associated with increased risk of implant dislocation (HR = 2.5,95% CI: 1.1–5.5 and HR = 3.7, 95% CI: 1.5–9.3, respectively as compared to those of normal weight). There was no statistically significant association between tobacco use and the risk of dislocation.Interpretation Greater attention should be..

Effect And Predictive Value Of Routine Preoperative Laboratory Testing For Endoscopic Retrograde Cholangiopancreatography

Background and Aims: Several studies and guidelines are questioning routine preoperative laboratory tests in surgical and endoscopic procedures. Their effect in endoscopic retrograde cholangiopancreatography is not currently known. This study was carried out to evaluate the risk of adverse effects in endoscopic retrograde cholangiopancreatography and their association with preoperative lab tests. Materials and Methods: A single-center, prospective observational study on all 956 patients undergoing 1196 endoscopic retrograde cholangiopancreatographies in the Endoscopy Unit of Helsinki University Central Hospital from 1 March 2012 to 28 February 2013. Routine preoperative laboratory test results (basic blood count, creatinine, potassium, sodium, international normalized ratio/thromboplastin time, and amylase), health status, medication, and demographic information of all patients were analyzed in relation to adverse effects related to endoscopic retrograde cholangiopancreatography and procedural sedation. Results: Multivariate analysis showed post-endoscopic retrograde cholangiopancreatography pancreatitis (43 cases, 3.6%) to have no association with abnormal routine preoperative laboratory tests. Respiratory depression caused by sedation (128 cases, 11%) was not associated with abnormal routine preoperative laboratory tests, and anemia was found to be a slightly protecting factor. Cardiovascular depression caused by sedation was associated with thrombocytopenia (odds ratio = 1.87, p = 0.025) and, in male patients, hyponatremia (odds ratio = 3.66, p <0.001). Incidence of other adverse effects was too low for statistical analysis. Conclusion: Routine universal preoperative lab testing was not found to be successful in predicting adverse effects in endoscopic retrograde cholangiopancreatography procedures. Laboratory testing should be done focusing on each patient's individual needs.Peer reviewe

Koebe 1/4-Theorem and Inequalities in N=2 Super-QCD

The critical curve ${\cal C}$ on which ${\rm Im}\,\hat\tau =0$, $\hat\tau=a_D/a$, determines hyperbolic domains whose Poincar\'e metric is constructed in terms of $a_D$ and $a$. We describe ${\cal C}$ in a parametric form related to a Schwarzian equation and prove new relations for $N=2$ Super $SU(2)$ Yang-Mills. In particular, using the Koebe 1/4-theorem and Schwarz's lemma, we obtain inequalities involving $u$, $a_D$ and $a$, which seem related to the Renormalization Group. Furthermore, we obtain a closed form for the prepotential as function of $a$. Finally, we show that $\partial_{\hat\tau} \langle {\rm tr}\,\phi^2\rangle_{\hat \tau}={1\over 8\pi i b_1}\langle \phi\rangle_{\hat\tau}^2$, where $b_1$ is the one-loop coefficient of the beta function.Comment: 11 pages, LaTex file, Expanded version: new results, technical details explained, misprints corrected and references adde

Monopoles and clusters

We define and study certain hyperkaehler manifolds which capture the asymptotic behaviour of the SU(2)-monopole metric in regions where monopoles break down into monopoles of lower charges. The rate at which these new metrics approximate the monopole metric is exponential, as for the Gibbons-Manton metric.Comment: v2.: relation to calorons mentioned; added explanation

Moduli-Space Dynamics of Noncommutative Abelian Sigma-Model Solitons

In the noncommutative (Moyal) plane, we relate exact U(1) sigma-model solitons to generic scalar-field solitons for an infinitely stiff potential. The static k-lump moduli space C^k/S_k features a natural K"ahler metric induced from an embedding Grassmannian. The moduli-space dynamics is blind against adding a WZW-like term to the sigma-model action and thus also applies to the integrable U(1) Ward model. For the latter's two-soliton motion we compare the exact field configurations with their supposed moduli-space approximations. Surprisingly, the two do not match, which questions the adiabatic method for noncommutative solitons.Comment: 1+15 pages, 2 figures; v2: reference added, to appear in JHE

Supersymmetric non-linear sigma-models with boundaries revisited

We study two-dimensional supersymmetric non-linear sigma-models with boundaries. We derive the most general family of boundary conditions in the non-supersymmetric case. Next we show that no further conditions arise when passing to the N=1 model. We present a manifest N=1 off-shell formulation. The analysis is greatly simplified compared to previous studies and there is no need to introduce non-local superspaces nor to go (partially) on-shell. Whether or not torsion is present does not modify the discussion. Subsequently, we determine under which conditions a second supersymmetry exists. As for the case without boundaries, two covariantly constant complex structures are needed. However, because of the presence of the boundary, one gets expressed in terms of the other one and the remainder of the geometric data. Finally we recast some of our results in N=2 superspace and discuss applications.Comment: LaTeX, 23 page