Mean Curvature Flow, Orbits, Moment Maps

Given a compact Riemannian manifold together with a group of isometries, we discuss MCF of the orbits and some applications: eg, finding minimal orbits. We then specialize to Lagrangian orbits in Kaehler manifolds. In particular, in the Kaehler-Einstein case we find a relation between MCF and moment maps which, for example, proves that the minimal Lagrangian orbits are isolated.Comment: 18 pages; minor change

Deformations of Asymptotically Conical Special Lagrangian Submanifolds

McLean studied the deformations of compact special Lagrangian submanifolds, showing in particular that they come in moduli spaces whose dimension depends only on the topology of the submanifold. In this article we study the analogous problem for non-compact, "asymptotically conical" SL submanifolds, with respect to various "boundary conditions at infinity".Comment: 38 pages. Several modifications, new references. To appear in Pacific J. Mat

Multidimensional relativistic MHD simulations of Pulsar Wind Nebulae: dynamics and emission

Pulsar Wind Nebulae, and the Crab nebula in particular, are the best cosmic laboratories to investigate the dynamics of magnetized relativistic outflows and particle acceleration up to PeV energies. Multidimensional MHD modeling by means of numerical simulations has been very successful at reproducing, to the very finest details, the innermost structure of these synchrotron emitting nebulae, as observed in the X-rays. Therefore, the comparison between the simulated source and observations can be used as a powerful diagnostic tool to probe the physical conditions in pulsar winds, like their composition, magnetization, and degree of anisotropy. However, in spite of the wealth of observations and of the accuracy of current MHD models, the precise mechanisms for magnetic field dissipation and for the acceleration of the non-thermal emitting particles are mysteries still puzzling theorists to date. Here we review the methodologies of the computational approach to the modeling of Pulsar Wind Nebulae, discussing the most relevant results and the recent progresses achieved in this fascinating field of high-energy astrophysics.Comment: 29 pages review, preliminary version. To appear in the book "Modelling Nebulae" edited by D. Torres for Springer, based on the invited contributions to the workshop held in Sant Cugat (Barcelona), June 14-17, 201

Deformations of calibrated subbundles of Euclidean spaces via twisting by special sections

We extend the "bundle constructions" of calibrated submanifolds, due to Harvey--Lawson in the special Lagrangian case, and to Ionel--Karigiannis--Min-Oo in the cases of exceptional calibrations, by "twisting" the bundles by a special (harmonic, holomorphic, parallel) section of a complementary bundle. The existence of such deformations shows that the moduli space of calibrated deformations of these "calibrated subbundles" includes deformations which destroy the linear structure of the fibre.Comment: 16 pages, no figures. Version 2: Only minor cosmetic and typographical revisions. To appear in "Annals of Global Analysis and Geometry.

Early and midterm results of frozen elephant trunk operation with Evita open stent-graft in patients with Marfan syndrome: results of a multicentre study

Background: Endovascular treatment of patients with Marfan syndrome (MFS) is not recommended. Hybrid procedures such as frozen elephant trunk (FET), which combines stent-graft deployment with an integrated non-stented fabric graft for proximal grafting and suturing, have not been previously evaluated. The aim of this study was to assess the safety and feasibility of FET operation in patients with MFS. Methods: Patients enrolled in the International E-vita Open Registry (IEOR) who underwent FET procedure between January 2001 and February 2020 meeting Ghent criteria for MFS were included in the study. Early and midterm results were retrospectively analyzed. Preoperative, postoperative and follow-up computed tomography angiography scans were analysed. Results: We analyzed 37 patients [mean age 38 ± 11 years, 65% men]. Acute or chronic aortic dissection was present in 35 (95%) patients (14 and 21 patients respectively). Two (5%) patients had an aneurysm without dissection. Malperfusion syndrome was present in 4 patients. Twenty-nine (78%) patients had history of aortic surgical interventions. The 30-day and in-hospital mortality amounted to 8 and 14% respectively. False lumen exclusion was present in 73% in stented segment in last postoperative CT. The overall 5-year survival was 71% and freedom from reintervention downstream was 58% at 5 years. Of the nine patients who required reintervention for distal aortic disease, one patient died. Conclusions: FET operation for patients with MFS can be performed with acceptable mortality and morbidity. In long-term follow-up no reinterventions on the aortic arch were required. FET allows for easier second stage operations providing platform for surgical and endovascular reinterventions

Prevalence, virulence and antimicrobial susceptibility of Salmonella spp., Yersinia enterocolitica and Listeria monocytogenes in european wild boar (Sus scrofa) hunted in Tuscany (central Italy)

Wild boar is an animal the population of which constantly increases in Europe. This animal plays an important role as a reservoir for several pathogens, including three of the most important zoonoses: salmonellosis, yersiniosis and listeriosis. The aim of this investigation was to eval-uate the occurrence of antimicrobial-resistant and virulence factor genes of Salmonella spp., Yersinia enterocolitica and Listeria monocytogenes isolated from wild boar in Tuscany (Central Italy). During two consequent hunting seasons (2018/2019 and 2019/2020), rectal swabs, spleens and livers were collected from 287 hunted wild boar to isolate strains. Each isolate was tested to investigate its an-timicrobial resistance and to detect virulence factor genes by PCR. Eighteen Salmonella strains (6.27%) were isolated. Of these, 66.7% were resistant to streptomycin, 13.4% to cephalothin, 6.67% to imipenem and one isolate (6.67%) was resistant simultaneously to five antimicrobials. Moreover, the most detected genes were sopE (73.4%), pipB (66.7%), sodCI (53.3%), spvR and spvC (46.7%). In total, 54 (17.8%) Yersinia enterocolitica were isolated; of them, 26 (48.1%), 9 (16.7%), 17 (31.5%), 1 (1.85%) and 1 (1.85%) belonged to biotypes 1, 2, 3, 4 and 5, respectively. All strains (100%) demon-strated resistance to cephalothin and 70.4% to amoxicillin-clavulanic acid, 55.6% to ampicillin, and 37.0% to cefoxitin. Additionally, the most detected genes were ystA (25.9%), inv (24.1%), ail (22.2%), ystB (18.5%) and virF (14.8%). Finally, only one Listeria monocytogenes isolate (0.35%) was obtained, belonging to serogroup IVb, serovar 4b, and it was found to be resistant to cefoxitin, cefotaxime and nalidixic acid. The results highlighted the role of wild boar as a carrier for pathogenic and antimi-crobial-resistant Salmonella spp., Yersinia enterocolitica and Listeria monocytogens, representing a possible reservoir for domestic animals and human pathogens

Equation of state and magnetic susceptibility of spin polarized isospin asymmetric nuclear matter

Properties of spin polarized isospin asymmetric nuclear matter are studied within the framework of the Brueckner--Hartree--Fock formalism. The single-particle potentials of neutrons and protons with spin up and down are determined for several values of the neutron and proton spin polarizations and the asymmetry parameter. It is found an almost linear and symmetric variation of the single-particle potentials as increasing these parameters. An analytic parametrization of the total energy per particle as a function of the asymmetry and spin polarizations is constructed. This parametrization is employed to compute the magnetic susceptibility of nuclear matter for several values of the asymmetry from neutron to symmetric matter. The results show no indication of a ferromagnetic transition at any density for any asymmetry of nuclear matter.Comment: 23 pages, 8 figures, 2 tables (submitted to Phys. Rev. C