226 research outputs found

    Invariant solutions to the Strominger system and the heterotic equations of motion

    Get PDF
    We construct many new invariant solutions to the Strominger system with respect to a 2-parameter family of metric connections ε,ρ\nabla^{\varepsilon,\rho} in the anomaly cancellation equation. The ansatz ε,ρ\nabla^{\varepsilon,\rho} is a natural extension of the canonical 1-parameter family of Hermitian connections found by Gauduchon, as one recovers the Chern connection c\nabla^{c} for (ε,ρ)=(0,12)({\varepsilon,\rho})=(0,\frac12), and the Bismut connection +\nabla^{+} for (ε,ρ)=(12,0)({\varepsilon,\rho})=(\frac12,0). In particular, explicit invariant solutions to the Strominger system with respect to the Chern connection, with non-flat instanton and positive α\alpha' are obtained. Furthermore, we give invariant solutions to the heterotic equations of motion with respect to the Bismut connection. Our solutions live on three different compact non-K\"ahler homogeneous spaces, obtained as the quotient by a lattice of maximal rank of a nilpotent Lie group, the semisimple group SL(2,C\mathbb{C}) and a solvable Lie group. To our knowledge, these are the only known invariant solutions to the heterotic equations of motion, and we conjecture that there is no other such homogeneous space admitting an invariant solution to the heterotic equations of motion with respect to a connection in the ansatz ε,ρ\nabla^{\varepsilon,\rho}.Comment: 27 pages, 3 figure

    On the influence of transitively normal subgroups on the structure of some infinite groups

    Get PDF
    A transitively normal subgroup of a group G is one that is normal in every subgroup in which it is subnormal. This concept is obviously related to the transitivity of normality because the latter holds in every subgroup of a group G if and only if every subgroup of G is transitively normal. In this paper we describe the structure of a group whose cyclic subgroups (or a part of them) are transitively normal

    Six-Dimensional Solvmanifolds with Holomorphically Trivial Canonical Bundle

    Get PDF
    We determine the 6D solvmanifolds admitting an invariant complex structure with holomorphically trivial canonical bundle. Such complex structures are classified up to isomorphism, and the existence of strong Kähler with torsion, generalized Gauduchon, balanced and strongly Gauduchon metrics is studied. As an application, we construct a holomorphic family (M,Ja) of compact complex manifolds such that (M,Ja) satisfies the ¿¿¯-lemma and admits a balanced metric for any a¿0, but the central limit neither satisfies the ¿¿¯-lemma nor admits balanced metrics

    On the structure of some infinite dimensional linear groups

    Get PDF
    If G is a group and if the upper hypercenter, Z, of G is such that G/Z is finite then a recent theorem shows that G contains a finite normal subgroup L such that G/L is hypercentral. The purpose of the current paper is to obtain a version of this result for subgroups G of GL(F,A), when A is an infinite dimensionalF-vector space

    Locally nilpotent linear groups with the weak chain conditions on subgroups of infinite central dimension

    Get PDF
    Let V be a vector space over a field F. If G≤GL(V, F), the central dimension of G is the F-dimension of the vector space V/CV (G). In [DEK] and [KS], soluble linear groups in which the set Licd(G) of all proper infinite central dimensional subgroups of G satisfies the minimal condition and the maximal condition, respectively, have been described. On the other hand, in [MOS], periodic locally radical linear groups in which Licd(G) satisfies one of the weak chain conditions (the weak minimal condition or the weak maximal condition) have been characterized. In this paper, we begin the study of the non-periodic case by describing locally nilpotent linear groups in which Licd(G) satisfies one of the two weak chain conditions

    Common iliac aneurysms with short or absent proximal necks: Endoluminal repair with a covered endoprosthesis

    Get PDF
    AbstractEur J Vasc Endovasc Surg 26, 334-336 (2003

    Direct decompositions of artinian modules related to formations of groups

    No full text
    We survey direct decompositions of artinian modules over group rings into two summands where all the chief factors of the first are X–central and all the chief factors of the other is X–eccentric, where X is a certain formation of finite groups

    Liver Resection after Downstaging Hepatocellular Carcinoma with Sorafenib

    Get PDF
    Background. Sorafenib is a molecular-targeted therapy used in palliative treatment of advanced hepatocellular carcinoma in Child A patients. Aims. To address the question of sorafenib as neoadjuvant treatment. Methods. We describe the cases of 2 patients who had surgery after sorafenib. Results. The patients had a large hepatocellular carcinoma in the right liver with venous neoplastic thrombi (1 in the right portal branch, 1 in the right hepatic vein). After 9 months of sorafenib, reassessment showed that tumours had decreased in size with a necrotic component. A right hepatectomy with thrombectomy was performed, and histopathology showed 35% to 60% necrosis. One patient had a recurrence after 6 months and had another liver resection; they are both recurrence-free since then. Conclusion. Sorafenib can downstage hepatocellular carcinoma and thus could represent a bridge to surgery. It may be possible to select patients in good general condition with partial regression of the tumour with sorafenib for a treatment in a curative intent

    Endovascular retrieval of two migrated venous stents by means of balloon catheters

    Get PDF
    AbstractThe usefulness of vascular stenting was demonstrated in both arterial and venous applications to restore patency and improve suboptimal results after percutaneous transluminal angioplasty. Dislodgment of venous stents with an embolization into the right cavities or the pulmonary artery, however, is one of the most feared complications of this procedure. Percutaneous removal of these migrated stents is an appealing method of replacing more invasive operative intervention with cardiopulmonary bypass, which may be very hazardous in these often severely ill patients. We describe the cases of two patients with stents that migrated into the right ventricle and the pulmonary artery. In one patient, we were able to successfully remove these stents by using an angioplasty balloon with an operative extraction from the iliac vein, thereby obviating the need for a major operative procedure. (J Vasc Surg 1998;28:541-6.
    corecore