Evolution along the sequence of S0 Hubble types induced by dry minor mergers. II - Bulge-disk coupling in the photometric relations through merger-induced internal secular evolution

Galaxy mergers are considered as questionable mechanisms for the evolution of lenticular galaxies (S0's), on the basis that even minor ones induce structural changes that are difficult to reconcile with the strong bulge-disk coupling observed in the photometric scaling relations of S0's. We check if the evolution induced onto S0's by dry intermediate and minor mergers can reproduce their photometric scaling relations, analysing the bulge-disk decompositions of the merger simulations presented in Eliche-Moral et al. (2012). The mergers induce an evolution in the photometric planes compatible with the data of S0's, even in those ones indicating a strong bulge-disk coupling. The mergers drive the formation of the observed photometric relation in some cases, whereas they induce a slight dispersion compatible with data in others. Therefore, this evolutionary mechanism tends to preserve these scaling relations. In those photometric planes where the morphological types segregate, the mergers always induce evolution towards the region populated by S0's. The structural coupling of the bulge and the disk is preserved or reinforced because the mergers trigger internal secular processes in the primary disk that induce significant bulge growth, even although these models do not induce bars. Intermediate and minor mergers can thus be considered as plausible mechanisms for the evolution of S0's attending to their photometric scaling relations, as they can preserve and even strengthen any pre-existing structural bulge-disk coupling, triggering significant internal secular evolution (even in the absence of bars or dissipational effects). This means that it may be difficult to isolate the effects of pure internal secular evolution from those of the merger-driven one in present-day early-type disks (abridged).Comment: Accepted for publication in Astronomy & Astrophysics, 13 pages, 8 figures. Definitive version after proofs. Added references and corrected typo

Evaluación financiera de producción de pejelagarto (atractosteus tropicus): Caso cooperativa de producción pesquera acuícola "El pejelagarto", S.C. de R.L.

Se evalúo la rentabilidad de la producción de pejelagarto (Atractosteus tropicus) en dos modalidades de cultivo, en condiciones de cautiverio y en cautiverio en asociación con la mojarra castarrica y tilapia en la Sociedad Cooperativa de Producción Acuícola "El Pejelagarto", localizada en Sabancuy, municipio de Carmen, Campeche, México. Para tal efecto, se utilizaron los registros de 10 años para el cálculo de los indicadores de evaluación económica siguientes para el primer modo de cultivo: valor actual neto (VAN), relación beneficio-costo (B/C), relación beneficio-inversión neta (K/N) y la tasa interna de retorno (TIR). Los resultados obtenidos, para este período, fueron: VAN = 119,825.00, B/C = 1.08, N/K = 1.88 y TIR = 25.6%. Los indicadores para el cultivo en asociación fueron VAN = 629,254, B/C = 1.43, N/K = 10.15 y TIR = 145.0%. Con base en los resultados de los indicadores, se concluye que el proyecto productivo es viable en sus dos modalidades de cultivo, desde el punto de vista económico; por lo anterior, la cría, producción y comercialización de pejelagarto, tiene una gran oportunidad de negocio, por ser una especie con demanda, dentro y fuera de la región, por su rusticidad en la cría además de ser considerado un platillo exótico

Lyapunov exponents from CHUA's circuit time series using artificial neural networks

In this paper we present the general problem of identifying if a nonlinear dynamic system has a chaotic behavior. If the answer is positive the system will be sensitive to small perturbations in the initial conditions which will imply that there is a chaotic attractor in its state space. A particular problem would be that of identifying a chaotic oscillator. We present an example of three well known different chaotic oscillators where we have knowledge of the equations that govern the dynamical systems and from there we can obtain the corresponding time series. In a similar example we assume that we only know the time series and, finally, in another example we have to take measurements in the Chua's circuit to obtain sample points of the time series. With the knowledge about the time series the phase plane portraits are plotted and from them, by visual inspection, it is concluded whether or not the system is chaotic. This method has the problem of uncertainty and subjectivity and for that reason a different approach is needed. A quantitative approach is the computation of the Lyapunov exponents. We describe several methods for obtaining them and apply a little known method of artificial neural networks to the different examples mentioned above. We end the paper discussing the importance of the Lyapunov exponents in the interpretation of the dynamic behavior of biological neurons and biological neural networks

OH rotational lines as a diagnostic of the warm neutral gas in galaxies

We present Infrared Space Observatory (ISO) observations of several OH, CH and H2O rotational lines toward the bright infrared galaxies NGC253 and NGC1068. As found in the Galactic clouds in SgrB2 and Orion, the extragalactic far-IR OH lines change from absorption to emission depending on the physical conditions and distribution of gas and dust along the line of sight. As a result, most of the OH rotational lines that appear in absorption toward NGC253 are observed in emission toward NGC1068. We show that the far-IR spectrum of OH can be used as a powerful diagnostic to derive the physical conditions of extragalactic neutral gas. In particular, we find that a warm (Tk~150 K, n(H2)< 5 10^4 cm^-3) component of molecular gas with an OH abundance of 10^{-7} from the inner <15'' can qualitatively reproduce the OH lines toward NGC253. Similar temperatures but higher densities (5 10^5 cm^-3) are required to explain the OH emission in NGC1068.Comment: 5 pages, 4 figures, accepted in ApJ Part I (2004, October 6

Measuring The Costs Of Protection In Venezuela

This research looks into the static effects on the Venezuelan economy of removing trade barriers in the form of tariffs in textiles, agricultural products, steel and automobile. Based on a methodology used by the United States International Trade Commission, this paper documents that gains to consumers for every job lost range from $85,384 in the agricultural industry to$1,096,714 in the automobile industry. Removal of these barriers would increase national welfare in excess of $1 billion per year, which is equivalent to 1% of Venezuelas GDP (based on statistics from the 90s). This evidence suggests significant misallocation of resources that may retard the growth process

Compuestos polímero-metal con aplicaciones biomédicas

Este artículo describe la síntesis por plasma y la caracterización de compuestos polímero-metal con posibles aplicaciones como biomateriales. Se tomó particular atención en el tamaño de los agregados metálicos, en la rugosidad y en su hidrofilicidad. Se obtuvieron compuestos con conductividades eléctricas que van desde el intervalo correspondiente al de los semiconductores, hasta compuestos con conductividad metálica

Learning-related translocation of δ-opioid receptors on ventral striatal cholinergic interneurons mediates choice between goal-directed actions.

The ability of animals to extract predictive information from the environment to inform their future actions is a critical component of decision-making. This phenomenon is studied in the laboratory using the pavlovian-instrumental transfer protocol in which a stimulus predicting a specific pavlovian outcome biases choice toward those actions earning the predicted outcome. It is well established that this transfer effect is mediated by corticolimbic afferents on the nucleus accumbens shell (NAc-S), and recent evidence suggests that delta-opioid receptors (DORs) play an essential role in this effect. In DOR-eGFP knock-in mice, we show a persistent, learning-related plasticity in the translocation of DORs to the somatic plasma membrane of cholinergic interneurons (CINs) in the NAc-S during the encoding of the specific stimulus-outcome associations essential for pavlovian-instrumental transfer. Wefound that increased membrane DOR expression reflected both stimulus-based predictions of reward and the degree to which these stimuli biased choice during the pavlovian-instrumental transfer test. Furthermore, this plasticity altered the firing pattern of CINs increasing the variance of action potential activity, an effect that was exaggerated by DOR stimulation. The relationship between the induction of membrane DOR expression in CINs and both pavlovian conditioning and pavlovian-instrumental transfer provides a highly specific function for DOR-related modulation in the NAc-S, and it is consistent with an emerging role for striatal CIN activity in the processing of predictive information. Therefore, our results reveal evidence of a long-term, experience-dependent plasticity in opioid receptor expression on striatal modulatory interneurons critical for the cognitive control of action