226 research outputs found
Invariant solutions to the Strominger system and the heterotic equations of motion
We construct many new invariant solutions to the Strominger system with
respect to a 2-parameter family of metric connections
in the anomaly cancellation equation. The ansatz
is a natural extension of the canonical 1-parameter
family of Hermitian connections found by Gauduchon, as one recovers the Chern
connection for , and the Bismut
connection for . In particular,
explicit invariant solutions to the Strominger system with respect to the Chern
connection, with non-flat instanton and positive 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,) 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 .Comment: 27 pages, 3 figure
On the influence of transitively normal subgroups on the structure of some infinite groups
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
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
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
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
AbstractEur J Vasc Endovasc Surg 26, 334-336 (2003
Direct decompositions of artinian modules related to formations of groups
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
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
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.
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