Persistence of Invariant Tori on Submanifolds in Hamiltonian Systems

AMS (MOS). Mathematics Subject Classification. 58F05, 58F27, 58F30.Generalizing the degenerate KAM theorem under the Rüssmann non-degeneracy and the isoenergetic KAM theorem, we employ a quasi-linear iterative scheme to study the persistence and frequency preservation of invariant tori on a smooth sub-manifold for a real analytic, nearly integrable Hamiltonian system. Under a nondegenerate condition of Rüssmann type on the sub-manifold, we shall show the following: a) the majority of the unperturbed tori on the sub-manifold will persist; b) the perturbed toral frequencies can be partially preserved according to the maximal degeneracy of the Hessian of the unperturbed system and be fully preserved if the Hessian is nondegenerate; c) the Hamiltonian admits normal forms near the perturbed tori of arbitrarily prescribed high order. Under a sub-isoenergetic nondegenerate condition on an energy surface, we shall show that the majority of unperturbed tori give rise to invariant tori of the perturbed system of the same energy which preserve the ratio of certain components of the respective frequencies.The first author is partially supported by NSFC grant 19971042, National 973 key Project: Nonlinearity in China and the outstanding youth project of Ministry of Education of China. The second author is partially supported by NSF grant DMS9803581. This work is partially done when the second and third authors were visiting the National University of Singapore

Separation of Different Contributions to the Total X-ray Luminosity in Gamma-ray Loud Blazars

The relativistic beaming model has been successfully used to explain many of the observational properties of active galactic nuclei. In this model the total emission is formed by two components, one beamed, one unbeamed. However, the exact contribution from each component in unresolved sources is still not clear. In the radio band, the core and extended emissions are clearly separated. We adopt the method proposed by Kembhavi to separate the two contributions in the X-ray emissions in a sample of 19 gamma-ray loud blazars. It is clearly shown that the beamed emission dominates the X-ray flux and the unbeamed X-ray emission is correlated with the extended radio emission of the considered objects. We also find that the ratio of the beamed to the unbeamed X-ray luminosity is correlated with the X-ray spectral index, an effect that should be a consequence of the underlying X-ray emission mechanism.Fil: Fan, Jun Hui. Guangzhou University. Center for Astrophysics; ChinaFil: Romero, Gustavo Esteban. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto Argentino de Radioastronomía. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto Argentino de Radioastronomía; ArgentinaFil: Wang, Yong Xiang. College of Science and Trade; ChinaFil: Zhang, Jiang Shui. Guangzhou University. Center for Astrophysics; Chin

Lattice Boltzmann Approach to High-Speed Compressible Flows

We present an improved lattice Boltzmann model for high-speed compressible flows. The model is composed of a discrete-velocity model by Kataoka and Tsutahara [Phys. Rev. E \textbf{69}, 056702 (2004)] and an appropriate finite-difference scheme combined with an additional dissipation term. With the dissipation term parameters in the model can be flexibly chosen so that the von Neumann stability condition is satisfied. The influence of the various model parameters on the numerical stability is analyzed and some reference values of parameter are suggested. The new scheme works for both subsonic and supersonic flows with a Mach number up to 30 (or higher), which is validated by well-known benchmark tests. Simulations on Riemann problems with very high ratios ($1000:1$) of pressure and density also show good accuracy and stability. Successful recovering of regular and double Mach shock reflections shows the potential application of the lattice Boltzmann model to fluid systems where non-equilibrium processes are intrinsic. The new scheme for stability can be easily extended to other lattice Boltzmann models.Comment: Figs.11 and 12 in JPEG format. Int. J. Mod. Phys. C (to appear

Chronic ingestion of alcohol modulates expression of ubiquitin editing enzyme A20 in lung macrophages

BACKGROUND: Alcohol abuse is involved in the pathogenesis of multiple organ disorders; the underlying mechanism is incompletely understood. The ubiquitin editing enzyme A20 is involved in regulating activities in the cell. Suppression of A20 is suggested as one factor in the initiation of inflammation. This study investigates the mechanism by which chronic alcohol consumption modulates the levels of ubiquitin editing enzyme A20 in macrophages and further contributes to induce endothelial barrier dysfunction in the lung. METHODS: Mice were gavage-fed with 40% alcohol daily for 0-3 weeks. Airway macrophages were collected by lung lavage. Expression of ubiquitin editing enzyme A20 in isolated macrophages was assessed at both mRNA and protein levels. The endothelial barrier function of the lung was evaluated by the Evans blue method. RESULTS: Mice treated with alcohol for 3 weeks showed an increase in cell infiltration in the lung in response to exposure to peptidoglycan; over 80% of the infiltrated cells were macrophages. Furthermore, we observed that A20 level was suppressed in macrophages of mice treated with alcohol; the levels of tumor necrosis factor, interleukin-6 and nuclear factor kappa B in macrophage were increased. In addition, the endothelial barrier function of the lung was compromised, showing excessive infiltration of Evans blue in the lung indicating lung edema. Pretreatment with synthesized A20 inhibited alcohol-induced lung endothelial barrier dysfunction. CONCLUSIONS: We conclude that chronic alcohol ingestion disturbs the endothelial barrier function in the lung by modulating macrophage properties. Increase in A20 in the cell may have potential for the treatment of inflammatory disorders

Percutaneous closure of a post-traumatic ventricular septal defect with a patent ductus arteriosus occluder

OBJECTIVE: Ventricular septal defects resulting from post-traumatic cardiac injury are very rare. Percutaneous closure has emerged as a method for treating this disorder. We wish to report our experience in three patients who underwent percutaneous closure of a post-traumatic ventricular septal defect with a patent ductus arteriosus occluder. METHODS: We treated three patients with post-traumatic ventricular septal defects caused by stab wounds with knives. After the heart wound was repaired, patient examinations revealed ventricular septal defects with pulmonary/systemic flow ratios (Qp/Qs) of over 1.7. The post-traumatic ventricular septal defects were closed percutaneously with a patent ductus arteriosus occluder (Lifetech Scientific (Shenzhen) Co., LTD, Guangdong, China) utilizing standard techniques. RESULTS: Post-operative transthoracic echocardiography revealed no residual left-to-right shunt and indicated normal ventricular function. In addition, 320-slice computerized tomography showed that the occluder was well placed and exhibited normal morphology. CONCLUSION: Our experiences indicate that closure of a post-traumatic ventricular septal defect using a patent ductus arteriosus occluder is feasible, safe, and effective

A general QoS aware flow-balancing and resource management scheme in distributed software-defined networks

Due to the limited service capabilities of centralized controllers, it is difficult to process high volume of flows within reasonable time. This particularly degrades the strict quality of service (QoS) requirements of interactive media applications, which is non-negligible factor. To alleviate this concern, distributed deployments of software-defined network (SDN) controllers are inevitable and have gained a predominant position. However, to maintain application specific QoS requirements, the number of resources used in network directly impacts the capital and operational expenditure. Hence, in distributed SDN architectures, issues such as flow arrival rate, resources required and operational cost have significant mutual dependencies on each other. Therefore, it is essential to research feasible methods to maintain QoS and minimize resources provisioning cost. Motivated from this, we propose a solution in a distributed SDN architectures that provides flow-balancing (with guaranteed QoS) in pro-active operations of SDN controllers, and attempts to optimize the use of instance resources provisioning costs. We validate our solution using the tools of queuing theory. Our studies indicate that with our solution, a network with minimum resources and affordable cost with guaranteed application QoS can be set-up