9,172 research outputs found
B2 and G2 Toda systems on compact surfaces: a variational approach
We consider the B2 and G2 Toda systems on compact surfaces. We attack the
problem using variational techniques. We get existence and multiplicity of
solutions under a topological assumption on the surface and some generic
conditions on the parameters. We also extend some of the results to the case of
general systems.Comment: 28 pages, accepted on Journal of Mathematical Physic
Keeping watch over Colombia’s slumbering volcanoes
The Volcanological and Seismological Observatories of Manizales, Pasto and Popayan (Colombian Geological Survey) monitor and study the active volcanoes of Colombia using seismological, geodetic, geochemical and other techniques. Since 2009, permanent GNSS stations have been installed to complement classical geodetic measurements (e.g., tilt, EDM). At the moment, there are a total of 20 GNSS stations installed at Nevado del Ruiz, Cerro MachĂn, PuracĂ© and Galeras volcanoes.
Nevado del Ruiz has remained the most dynamic of the active Colombian volcanoes since its tragic eruption of 13 November 1985. The most significant deformation occurred between 2007 and 2012, when inflation, associated with magma migration and several small to moderate explosive eruptions in 2012 (VEI less or equal to 3), was observed.
Galeras has experienced more than 25 moderate Vulcanian eruptions (VEI less or equal to 3) since 1989. In particular, the deformation network detected significant signals associated with magma migration and the extrusion of lava domes in 1991, 2005, 2008 and 2012.
Puracé volcano has been the site of more than 10 minor eruptive episodes (VEI=2) in the past century, most recently in 1977. Monitoring of this volcano started in 1994. Unrest at Puracé since that time has been characterized by significant increases in seismic activity but with little or no deformation.
We employ GAMIT/GLOBK to process GPS data from the monitoring network with support from the Volcano Disaster Assistance Program (U.S. Geological Survey). Additionally, differential processing is carried out using the commercial package Trimble 4D Control. Preliminary results for 2012 show no significant deformation at Puracé and Galeras volcanoes. On the other hand, the time series from Nevado del Ruiz shows a minor inflation (2-4 cm/yr) associated with the eruptive activity of 2012
Identifying the contributions of Universal Extra Dimensions in the Higgs sector at linear e+ e- colliders
We study the dilepton-dijet signal in the dominant Higgs production channel
at a linear e+ e- collider. We estimate the effects of Universal Extra
Dimension (UED) by a simple analysis of the cross-sections. The heavy
Kaluza-Klein excitations of the Standard Model fields in UED can significantly
alter the decay properties of the Higgs boson to loop-driven final states. We
show that by taking a simple ratio between cross-sections of two different
final states this difference can be very easily highlighted.Comment: Some parts of the text modified. 1 figure added. Version to appear in
IJMP
Numerical simulation of sloshing in liquid storing tanks by an arbitrary Lagrangian-Eulerian strategy
La agitaciĂłn de fluidos contenidos en tanques de almacenamiento con superficie libre es numĂ©ricamente simulada mediante una formulaciĂłn lagrangiana-euleriana arbitraria. El fluido es considerado viscoso y de comportamiento newtoniano, mientras que el flujo se asume laminar e incompresible. Se emplea un cĂłdigo computacional particionado y distribuido, que resuelve tres instancias en cada paso de tiempo: (i) la determinaciĂłn del estado en el fluido, representado por las ecuaciones de Navier–Stokes; (ii) el desplazamiento de la superficie libre; y (iii) la actualizaciĂłn de la posiciĂłn de los nodos interiores de la malla de elementos finitos, que es deformada como consecuencia del desplazamiento de la superficie libre. El propĂłsito del trabajo es verificar la aplicabilidad del mĂ©todo en problemas de agitaciĂłn de soluciĂłn conocida, asĂ como tambiĂ©n resolver algunos ejemplos prácticos. Los ejemplos numĂ©ricos incluyen la validaciĂłn con soluciones analĂticas, en las cuales el perĂodo de la onda y la tasa de amortiguamiento viscoso son bien capturadas, comparaciones con soluciones de referencia tomadas de otros autores y un caso de agitaciĂłn inducida por acciĂłn sĂsmica.Sloshing of fluids with a free surface contained in liquid storage tanks is numerically simulated by an arbitrary Lagrangian-Eulerian formulation. The fluid is considered viscous and Newtonian, while the flow is assumed laminar and incompressible. A partitioned and distributed computational code is employed, which solves three instances each time step: (i) the determination of the fluid state, given by the Navier–Stokes equations; (ii) the displacement of the free surface; and (iii) the update of the position of the internal nodes of the mesh, that is deformed as a consequence of the free surface displacement. The purpose of the work is verifying the applicability of the method to sloshing problems with known solutions, as well as the resolution of some practical examples. Numerical examples include validations against analytical solutions, where the wave period and damping rate are well captured, comparisons with reference results from other authors and a sample of sloshing induced by seismic actions.Peer Reviewe
Cellular delivery of antibodies: effective targeted subcellular imaging and new therapeutic tool
It is already more than a century since the pioneering work of the Nobel Laureate Ehrlich gave birth to the side chain theory1, which helped to define antibodies and their ability to target specific biological sites. However, the use of antibodies is still restricted to the extracellular space due to the lack of a suitable delivery vehicle for the efficient transport of antibodies into live cells without inducing toxicity. In this work, we report the efficient encapsulation and delivery of antibodies into live cells with no significant loss of cell viability or any deleterious affect on the cell metabolic activity. This delivery system is based on poly(2-(methacryloyloxy)ethyl phosphorylcholine)-block-(2-(diisopropylamino)ethyl methacrylate), (PMPC-PDPA), a pH sensitive diblock copolymer that self-assembles to form nanometer-sized vesicles, also known as polymersomes, at physiological pH. These polymersomes can successfully deliver relatively high antibody payloads within live cells. Once inside the cells, we demonstrate that these antibodies can target their epitope by immune-labelling of cytoskeleton, Golgi, and transcription factor proteins in live cells. We also demonstrate that this effective antibody delivery mechanism can be used to control specific subcellular events, as well as modulate cell activity and pro-inflammatory process
Heavy Quark Parameters and Vcb from Spectral Moments in Semileptonic B Decays
We extract the heavy quark masses and non-perturbative parameters from the
Delphi preliminary measurements of the first three moments of the charged
lepton energy and hadronic mass distributions in semileptonic B decays, using a
multi-parameter fit. We adopt two formalisms, one of which does not rely on a
1/mc expansion and makes use of running quark masses. The data are consistent
and the level of accuracy of the experimental inputs largely determines the
present sensitivity. The results allow to improve on the uncertainty in the
extraction of Vcb.Comment: 13 pages, 2 figure
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