Filosofía para no filósofos

-¿Quiénes son los no filósofos y qué es la filosofía? Contestar a la pregunta sobre quiénes no son filósofos es relativamente fácil, y la respuesta es simple: son los que no estudiaron filosofía, quienes no poseen el título académico de filósofo. En este sentido, resulta casi un hecho que pocos hombres o mujeres sean filósofos o filósofas, pero esto no es necesariamente así. En el presente trabajo se da cuenta de la labor de la filosofía fuera de la academis, es decir, en el transcurrir diario

Monthly 43 GHz VLBA Polarimetric Monitoring of 3C120 over 16 Epochs: Evidence for Trailing Shocks in a Relativistic Jet

We present a 16-month sequence of monthly polarimetric 43 GHz VLBA images of the radio galaxy 3C 120. The images probe the inner regions of the radio jet of this relatively nearby superluminal radio galaxy at a linear resolution of 0.07 $h_{65}^{-1}$ pc ($H_o= 65 h_{65}$ km s$^{-1}$ Mpc$^{-1}$). We follow the motion of a number of features with apparent velocities between 4.01$\pm$0.08 and $5.82\pm 0.13 h_{65}^{-1} c$. A new superluminal knot, moving at $4.29\pm 0.16 h_{65}^{-1} c$, is observed to be ejected from the core at a time coincident with the largest flare ever observed for this source at millimeter wavelengths. Changes in the position angle of this component, as well as a progressive rotation of its magnetic polarization vector, suggest the presence of a twisted (resembling a helix in projection) configuration of the underlying jet magnetic field and jet geometry. We identify several knots that appear in the wake of the new superluminal component, moving at proper motions $\sim 4$ times slower than any of the other moving knots observed in 3C 120. These features have properties similar to those of the ``trailing'' shocks seen in relativistic, time-dependent, hydrodynamical and emission simulations of compact jets. Such trailing compressions are triggered by pinch-mode jet-body instabilities caused by the propagation of a strong perturbation, which we associate with the new strong superluminal component.Comment: 4 pages, 5 figures, accepted for publication in Astrophysical Journal Letter

The CreC regulator of Escherichia coli, a new target for metabolic manipulations

The CreBC (carbon source-responsive) two-component regulation system of Escherichia coli affects a number of functions, including intermediary carbon catabolism. The impacts of different creC mutations (a ΔcreC mutant and a mutant carrying the constitutive creC510 allele) on bacterial physiology were analyzed in glucose cultures under three oxygen availability conditions. Differences in the amounts of extracellular metabolites produced were observed in the null mutant compared to the wild-type strain and the mutant carrying creC510 and shown to be affected by oxygen availability. The ΔcreC strain secreted more formate, succinate, and acetate but less lactate under low aeration. These metabolic changes were associated with differences in AckA and LdhA activities, both of which were affected by CreC. Measurement of the NAD(P)H/NAD(P)+ ratios showed that the creC510 strain had a more reduced intracellular redox state, while the opposite was observed for the ΔcreC mutant, particularly under intermediate oxygen availability conditions, indicating that CreC affects redox balance. The null mutant formed more succinate than the wild-type strain under both low aeration and no aeration. Overexpression of the genes encoding phosphoenolpyruvate carboxylase from E. coli and a NADH-forming formate dehydrogenase from Candida boidinii in the ΔcreC mutant further increased the yield of succinate on glucose. Interestingly, the elimination of ackA and adhE did not significantly improve the production of succinate. The diverse metabolic effects of this regulator on the central biochemical network of E. coli make it a good candidate for metabolic-engineering manipulations to enhance the formation of bioproducts, such as succinate.Fil: Godoy, Manuel Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Nikel, Pablo Ivan. Consejo Superior de Investigaciones Científicas; EspañaFil: Cabrera Gomez, José Gregorio. Unviversidad de San Pablo; BrasilFil: Pettinari, María Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentin

MAPCAT: Monitoring AGN with Polarimetry at the Calar Alto Telescopes

We introduce MAPCAT, a long-term observing program for "Monitoring of AGN with Polarimetry at the Calar Alto Telescopes". Multi-spectral-range studies are critical to understand some of the most relevant current problems of high energy astrophysics of blazars such as their high energy emission mechanisms and the location of their gamma-ray emission region through event associations across the spectrum. Adding multi-spectral-range polarimetry allows for even more reliable identification of polarized flares across the spectrum in these kind of objects, as well as for more accurate modeling of their magnetic field. As part of a major international effort to study the long term multi-spectral range polarimetric behavior of blazars, MAPCAT uses -since mid 2007- CAFOS on the 2.2m Telescope at the Calar Alto Observatory (Almeria, Spain) to obtain monthly optical (R-band) photo-polarimetric measurements of a sample of 34 of the brightest gamma-ray, optical, and radio-millimeter blazars accessible from the northern hemisphere.Comment: To be published in the proceedings of High Energy Phenomena in Relativistic Outflows III (HEPRO III, IJMPCS). 4 page