5,609 research outputs found
Delayed Scattering of Solitary Waves from Interfaces in a Granular Container
In granular media, the characterization of the behavior of solitary waves
around interfaces is of importance in order to look for more applications of
these systems. We study the behavior of solitary waves at both interfaces of a
symmetric granular container, a class of systems that has received recent
attention because it posses the feature of energy trapping. Hertzian contact is
assumed. We have found that the scattering process is elastic at one interface,
while at the other interface it is observed that the transmitted solitary wave
has stopped its movement during a time that gets longer when the ratio between
masses at the interfaces increases. The origin of this effect can be traced
back to the phenomenon of gaps opening, recently observed experimentally.Comment: To appear in Physical Review E, vol 7
Scattering of solitary waves in granular media
A detailed numerical study of the scattering of solitary waves by a barrier,
in a granular media with Hertzian contact, shows the existence of secondary
multipulse structures generated at the interface of two "sonic vacua", which
have a similar structure as the one previously found by Nesterenko and
coworkers.Comment: 4 pages, 9 figures (fig 5, replaced). Submitted to PR
Preliminary notes on invasion and proliferation of foodborne Listeria monocytogenes strains
In this study, virulence properties of L. monocytogenes strains isolated from food and food environments were evaluated. In particular, adhesion and invasion efficiencies were tested in a cell culture model (HeLa). Half of the isolates (9/18) exhibited a high invasion index. In particular, the strain isolated from smoked salmon had the highest invasion index. The remaining isolates showed an intermediate invasion index. All environmental isolates belonged to this group. Finally, no isolates revealed a low invasion index. Regarding intracellular growth, all tested isolates had a replication time between 2 and 6 hours. For this reason, they can be considered virulent. In spite of its capability to invade HeLa cells with a medium/high invasion index, a non-haemolytic rabbit isolate did not show any intracellular growth. In conclusion, differences in invasion efficiency and intracellular growth did not seem strictly related to the origin of the strains. Moreover, invasiveness of an organism is not the only requirement for establishing an infection. Virulence of L. monocytogenes also depends on ability to grow intracellularly and to spread from cell to cell. For these reasons, PCR detection of known virulence genes has the potential to gain additional insight into their pathogenic potential. A comprehensive comparative virulence characterization of different L. monocytogenes strains in studies that include tissue culture models and PCR detection of virulence genes will be necessary to investigate differences in human-pathogenic potentials among the subtypes of this bacterium
Drug-Related Cardiotoxicity for the Treatment of Haematological Malignancies in Elderly.
Meyer Paul Hugo. Diderot oder die Ambivalenz der Aufklärung, Neumann, 1987. In: Recherches sur Diderot et sur l'Encyclopédie, n°4, 1988. pp. 164-165
Relación entre la capacidad antioxidante de mieles con su origen botánico
Fil: Vergara-Roig, V. A. Universidad Nacional de Catamarca. Facultad de Ciencias Exactas y Naturales. Departamento de Química; Argentina.Fil: Costa, M. C. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Área Proyectos Especiales; Argentina.Fil: Kivatinitz, S. C. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Biológica-CIQUIBIC; Argentina.Partiendo de la hipótesis de que hay dependencia entre las variables físicoquímicas relacionadas con la capacidad antioxidante de la miel (contenido de
polifenoles, proteínas, flavonoides, capacidad antiradicalaria (CAR), color,
cenizas totales y acidez) con el origen botánico de la misma; se procedió a
analizar un conjunto de 39 mieles de diferente origen floral procedentes de
apiarios ubicados en distintas ecoregiones de la Provincia de Catamarca.Fil: Vergara-Roig, V. A. Universidad Nacional de Catamarca. Facultad de Ciencias Exactas y Naturales. Departamento de Química; Argentina.Fil: Costa, M. C. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Área Proyectos Especiales; Argentina.Fil: Kivatinitz, S. C. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Biológica-CIQUIBIC; Argentina.Otras Ciencias Naturales y Exacta
Lapatinib/Paclitaxel polyelectrolyte nanocapsules for overcoming multidrug resistance in ovarian cancer.
The sonication-assisted layer-by-layer (SLBL) technology was developed to combine necessary factors for an efficient drug-delivery system: (i) control of nanocolloid size within 100 - 300 nm, (ii) high drug content (70% wt), (iii) shell biocompatibility and biodegradability, (iv) sustained controlled release, and (v) multidrug-loaded system. Stable nanocolloids of Paclitaxel (PTX) and lapatinib were prepared by the SLBL method. In a multidrug-resistant (MDR) ovarian cancer cell line, OVCAR-3, lapatinib/PTX nanocolloids mediated an enhanced cell growth inhibition in comparison with the PTX-only treatment. A series of in vitro cell assays were used to test the efficacy of these formulations. The small size and functional versatility of these nanoparticles, combined with their ability to incorporate various drugs, indicates that lapatinib/PTX nanocolloids may have in vivo therapeutic applications
The Hopf Algebra of Renormalization, Normal Coordinates and Kontsevich Deformation Quantization
Using normal coordinates in a Poincar\'e-Birkhoff-Witt basis for the Hopf
algebra of renormalization in perturbative quantum field theory, we investigate
the relation between the twisted antipode axiom in that formalism, the Birkhoff
algebraic decomposition and the universal formula of Kontsevich for quantum
deformation.Comment: 21 pages, 15 figure
Riemannian submersions from almost contact metric manifolds
In this paper we obtain the structure equation of a contact-complex
Riemannian submersion and give some applications of this equation in the study
of almost cosymplectic manifolds with Kaehler fibres.Comment: Abh. Math. Semin. Univ. Hamb., to appea
Tunability of solitary wave properties in one dimensional strongly nonlinear phononic crystals
One dimentional strongly nonlinear phononic crystals were assembled from
chains of PTFE (polytetrafluoroethylene) and stainless steel spheres with
gauges installed inside the beads. Trains of strongly nonlinear solitary waves
were excited by an impact. A significant modification of the signal shape and
an increase of solitary wave speed up to two times (at the same amplitude of
dynamic contact force)were achieved through a noncontact magnetically induced
precompression of the chains. Data for PTFE based chains are presented for the
first time and data for stainless steel based chains were extended into a
smaller range of amplitudes by more than one order of magnitude than previously
reported. Experimental results were found to be in reasonable agreement with
the long wave approximation and with numerical calculations based on Hertz
interaction law for discrete chains.Comment: 36 pages, 7 figure
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