Aspectos ecológicos de Chaetostoma sp. (Siluriformes: Loricariidae) en el alto río Magdalena, Colombia

We determined food and reproductive habits of Chaetostoma sp. in the Upper Magdalena basin, Colombia. The samplings were monthly between August 2001 and July 2012. We collected 1853 individuals in 11 size classes, between 34 â 114 mm SL, with an average length of 43.5 mm SL. The frequent recruitment was observed throughout the year, however the greater contribution of young individuals occurred between January and March 2012. Overall, Chaetostoma sp. was categorized as an hervibore with preference for diatoms. Navicula was the main food item, while Synedra, Gomphonema, Cymbella, Oscillatoria and Fragilaria were secondary food items. The sex ratio was 1:1. The average fecundity was 124 oocytes and average diameter of 1.54 mm, possibly related to a reproductive strategy K.Se determinaron los hábitos alimenticios y reproductivos de Chaetostoma sp. en el alto río Magdalena, Colombia. Los muestreos fueron mensuales entre agosto de 2011 y julio de 2012. Se colectaron 1853 individuos, distribuidos en 11 clases de tallas entre 34 â 114 mm LE, con una longitud media de 43,5 mm LE. Se observó un reclutamiento frecuente durante todo el año del muestreo, sin embargo el mayor aporte de individuos juveniles se presentó entre enero y marzo 2012. Chaetostoma sp. se categorizó como un herbívoro con preferencia por las diatomeas, donde Navicula fue el ítem principal, mientras que Synedra, Gomphonema, Cymbella, Oscillatoria y Fragilaria fueron ítems secundarios. La proporción sexual fue de 1:1, su fecundidad promedio fue de 124 oocitos y el diámetro de 1,54 mm, relacionado con estrategia reproductiva k. Proyecto financiado por Emgesa S. A. E.S.P

Synthesis and H+, Cu2+, and Zn2+ Coordination Behavior of a Bis(fluorophoric) Bibrachial Lariat Aza-Crown

The synthesis, protonation behavior, and Cu2+ and Zn2+ coordination chemistry of the novel bibrachial aza lariat ether (naphthalen-1-ylmethyl)[2-(20-{2-[(naphthalen-1-ylmethyl)amino]ethyl}-3,6,9,17,20,23,29,30-octaazatricyclo[23.3.1.1*11,15*]triaconta-1(29),11(30),12,14,25,27-hexaen-6-yl)ethyl]amine (L) are discussed. The macrocycle, which has two aminoethyl naphthyl moieties symmetrically appended to a 2:2 azapyridinophane structure, displays, in the pH range 2−11, six protonation steps that correspond to the protonation of the secondary amino groups. Steady-state fluorescence measurements show emissions due to the monomer and to the excimer formed between the two naphthalene fragments of the macrocycle. The time-resolved fluorescence data, obtained by the time-correlated single photon counting technique, show that a significant percentage of excimer is preformed as ground-state dimers. The ligand L forms with the metal ions Cu2+ and Zn2+ mono- and dinuclear complexes in aqueous solution. The influence of metal coordination in the fluorescence emission of L is analyzed. The acid−base, coordination capabilities, and emissive behavior of L are compared with those presented by its synthetic precursor L1, which has a tripodal tris(2-aminoethyl)amine structure functionalized at one of its terminal amino groups with a naphthyl moiet

Historia de vida del bagre Imparfinis usmai (Heptapteridae: Siluriformes) en el área de influencia del proyecto hidroeléctrico El Quimbo, alto río Magdalena, Colombia

In Colombia a dam, Betania Reservoir, has been constructed on the main cannel of the Magdalena River, and another, the El Quimbo Hydroelectric Project which is located upstream of the first, is under construction. The dams not only generate fragmentation processes in the aquatic ecosystems, but also create artificial hybrid systems that impact the populations of different species of fish that inhabit them. This study aims to determine the life history of Imparfinis usmai and establish its trophodynamics in the area of influence of the El Quimbo Hydroelectric Project. Monthly samples were made from August 2011 to July 2012 in Garzón, Rioloro, Guandinosa and Yaguilga streams, and Páez, Suaza and Magdalena rivers. A total of 278 specimens, distributed in nine size classes were collected. In general, the population has a positive allometric growth, although variations occur throughout the year. The species was categorized as an Invertivore - Insectivore, and preferably consumed Simuliidae. The sex ratio was 1: 1.8, with predominance of females. Average fecundity was 2846 oocytes, with an extensive reproductive period. Project funded by Emgesa S. A. E.S.P.En Colombia se ha construido el embalse de Betania en el cauce principal del río Magdalena y el proyecto hidroeléctrico El Quimbo, localizado aguas arriba de este, se encuentra bajo construcción. Los embalses no solo generan procesos de fragmentación en los ecosistemas acuáticos, sino también crean sistemas artificiales híbridos que impactan las poblaciones de diferentes especies de peces que los habitan. El presente estudio tiene como meta conocer la historia de vida de Imparfinis usmai, así como establecer su patrón alimenticio, en el área de influencia del proyecto hidroeléctrico El Quimbo, embalse en fase de construcción en el cauce del río Magdalena. Para esto se efectuaron muestreos mensuales entre agosto de 2011 y julio de 2012, en las quebradas Garzón, Rioloro, Yaguilga y Guandinosa, y los ríos Páez, Suaza y Magdalena. Se colectaron 278 ejemplares, los cuales se distribuyeron en nueve clases de tallas. En general, la población presentó un crecimiento alométrico positivo, aunque con variaciones a lo largo del año. La especie se catalogó como invertívora - insectívora, con preferencia de Simuliidae. La proporción sexual fue de 1:1,8, con predominio de las hembras. Su fecundidad promedio fue de 2846 oocitos, con un periodo reproductivo extenso. Proyecto financiado por Emgesa S. A. E.S.P

Historia de vida del bagre <em>Imparfinis usmai<em> (Heptapteridae: Siluriformes) en el área de influencia del proyecto hidroeléctrico El Quimbo, alto río Magdalena, Colombia

In Colombia a dam, Betania Reservoir, has been constructed on the main cannel of the Magdalena River, and another, the El Quimbo Hydroelectric Project which is located upstream of the first, is under construction. The dams not only generate fragmentation processes in the aquatic ecosystems, but also create artificial hybrid systems that impact the populations of different species of fish that inhabit them. This study aims to determine the life history of Imparfinis usmai and establish its trophodynamics in the area of influence of the El Quimbo Hydroelectric Project. Monthly samples were made from August 2011 to July 2012 in Garzón, Rioloro, Guandinosa and Yaguilga streams, and Páez, Suaza and Magdalena rivers. A total of 278 specimens, distributed in nine size classes were collected. In general, the population has a positive allometric growth, although variations occur throughout the year. The species was categorized as an Invertivore - Insectivore, and preferably consumed Simuliidae. The sex ratio was 1: 1.8, with predominance of females. Average fecundity was 2846 oocytes, with an extensive reproductive period. Project funded by Emgesa S. A. E.S.P

Temas Socio-Jurídicos. Volumen 16 No. 35 Diciembre de 1998

La presente edición de la revista Temas socio-jurídicos, la número 35, en el año 16 de publicación periódica semestral, hace un reconocimiento expreso a la labor intelectual de uno de los creadores de la Facultad de Derecho, el doctor Alfonso Gómez Gómez, al cumplirse cincuenta años de haber optado el título de Doctor en Derecho.This issue of the Temas socio-jurídicos magazine, number 35, in its 16th year of semi-annual publication, expressly acknowledges the intellectual work of one of the creators of the Faculty of Law, Dr. Alfonso Gómez Gómez, by fifty years after having obtained the title of Doctor of Law

Measurement of the cosmic ray spectrum above 4×10184{\times}10^{18} eV using inclined events detected with the Pierre Auger Observatory

A measurement of the cosmic-ray spectrum for energies exceeding $4{\times}10^{18}$ eV is presented, which is based on the analysis of showers with zenith angles greater than $60^{\circ}$ detected with the Pierre Auger Observatory between 1 January 2004 and 31 December 2013. The measured spectrum confirms a flux suppression at the highest energies. Above $5.3{\times}10^{18}$ eV, the "ankle", the flux can be described by a power law $E^{-\gamma}$ with index $\gamma=2.70 \pm 0.02 \,\text{(stat)} \pm 0.1\,\text{(sys)}$ followed by a smooth suppression region. For the energy ($E_\text{s}$) at which the spectral flux has fallen to one-half of its extrapolated value in the absence of suppression, we find $E_\text{s}=(5.12\pm0.25\,\text{(stat)}^{+1.0}_{-1.2}\,\text{(sys)}){\times}10^{19}$ eV.Comment: Replaced with published version. Added journal reference and DO

Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory

The Auger Engineering Radio Array (AERA) is part of the Pierre Auger Observatory and is used to detect the radio emission of cosmic-ray air showers. These observations are compared to the data of the surface detector stations of the Observatory, which provide well-calibrated information on the cosmic-ray energies and arrival directions. The response of the radio stations in the 30 to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of the incoming electric field. For the latter, the energy deposit per area is determined from the radio pulses at each observer position and is interpolated using a two-dimensional function that takes into account signal asymmetries due to interference between the geomagnetic and charge-excess emission components. The spatial integral over the signal distribution gives a direct measurement of the energy transferred from the primary cosmic ray into radio emission in the AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air shower arriving perpendicularly to the geomagnetic field. This radiation energy -- corrected for geometrical effects -- is used as a cosmic-ray energy estimator. Performing an absolute energy calibration against the surface-detector information, we observe that this radio-energy estimator scales quadratically with the cosmic-ray energy as expected for coherent emission. We find an energy resolution of the radio reconstruction of 22% for the data set and 17% for a high-quality subset containing only events with at least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO

Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy

We measure the energy emitted by extensive air showers in the form of radio emission in the frequency range from 30 to 80 MHz. Exploiting the accurate energy scale of the Pierre Auger Observatory, we obtain a radiation energy of 15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV arriving perpendicularly to a geomagnetic field of 0.24 G, scaling quadratically with the cosmic-ray energy. A comparison with predictions from state-of-the-art first-principle calculations shows agreement with our measurement. The radiation energy provides direct access to the calorimetric energy in the electromagnetic cascade of extensive air showers. Comparison with our result thus allows the direct calibration of any cosmic-ray radio detector against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI. Supplemental material in the ancillary file