Caracterización de las rutas metabólicas de un lodo activado enriquecido en bacterias acumuladoras

Uno de los aspectos más importantes dentro del tratamiento de aguas residuales, con el sistema de lodos activados, es mantener una buena sedimentación para poder lograr un proceso más eficiente. Para ello, en ocasiones, se utilizan selectores con los cuales se favorece el crecimiento de las bacterias formadoras de flóculos sobre las filamentosas, que causan esponjamiento o “bulking” del lodo. En ese sentido, este trabajo de investigación buscó caracterizar un lodo operado con un selector no aireado. Esto con la finalidad de conocer a cuál modelo de lodos activados se ajustaba mejor y así lograr tener un mayor control del proceso y evitar problemas de sedimentación, los cuales ya se habían presentado en años anteriores. Además, aprovechando el uso de un selector, se planteó la posibilidad de estar trabajando con un cultivo enriquecido en bacterias acumuladoras de sustrato o fósforo. Siendo éstas últimas de gran importancia en la remoción biológica de nutrientes. Para lograr el objetivo anterior, se realizaron corridas de degradación en batch utilizando el lodo de los dos RBS con los que se trabajó en el proyecto. En éstas corridas se midieron cinéticas de DQO, fósforo, nitrógeno y utilización de oxígeno. Con los resultados obtenidos se verificó que las bacterias predominantes en el lodo fueron del tipo acumuladoras de sustrato, ajustándose mejor al modelo de lodos activados No.3 (ASM3), y se optimizó la operación teniendo especial cuidado en alcanzar una concentración de oxígeno disuelto óptimo (alrededor de 2 mg/L) al inicio de la fase aerobia en los reactores. Después se probó la hipótesis de que al aumentar la cantidad de fósforo presente en el agua residual, utilizada como alimento en los RBS, se puede favorecer el crecimiento de las bacterias acumuladoras de fósforo. Para ello, se montó otro reactor al que se le aumentó la concentración de fósforo en el alimento, pasando de 2 a 18 mg/L de P, y se estuvo monitoreando el comportamiento de los ortofosfatos en los ciclos de operación. Luego del monitoreo, se observó una remoción de fósforo importante pero no así el comportamiento metabólico típico para organismos de este tipo. Para descartar una remoción por precipitación química, debido al pH alto que se maneja en los reactores (>8.5), se montó un experimento controlando el pH a 7 utilizando el mismo lodo y la misma alimentación enriquecida con fósforo. Con esta prueba se observó que al descender el valor de pH ya no hubo remoción significativa de fósforo. Por lo que la ruta metabólica más predominante en el cultivo del lodo fue la de los GAO. Los resultados de toda la investigación lograron mantener estables los reactores biológicos y descartar que los problemas de sedimentación fueron por falta de nutrientes, si no por falta de oxígeno disuelto al momento de la degradación del sustrato. Además, dio las bases y conocimientos necesarios para desarrollar un proceso de remoción biológica de fósforo en futuros proyectos.CONACY

Pulsar J0453+1559, the 10th double neutron star system in the universe

Pulsars are neutron stars that spin rapidly, are highly magnetized, and they emit beams of electromagnetic radiation like a lighthouse out in space. These beams of radiation are only observed when the beams face towards Earth and can be measured by a radio telescope. Pulsar studies have an abundance of scientific implementations in solid state physics, general relativity, galactic astronomy, astronomy, planetary physics and have even opened windows in cosmology. This thesis reports the results of a study of pulsar (PSR) J0453+1559, a new binary pulsar discovered in the Arecibo All-Sky 327 MegaHertz Drift Pulsar Survey. The recorded observations of the times of arrivals of the pulses of the pulsar in the system, J0453+1559, span a period of about 320 days, which allowed precise measurement of its spin period (45.7 ms) and its derivative (1.85 ± 0.13 × 10−19 ss−1). From these measurements we derived the characteristic age of the system as ∼ 3.9 × 106 years and having a magnetic field of ∼ 2.9 × 109 G. These measurements point out that this pulsar was mildly recycled by gradual accumulation of matter from the companion star. The cyclic dance of this system has an eccentric (e = 0.11) 4.07-day orbit. This eccentricity enables a highly significant quantification of the rate of advance of periastron as ω˙ = 0.0379 ± 0.0005◦yr−1, which entails the total mass of the system as M = 2.73 ± 0.006 M. We also discovered the Shapiro delay, which allows an approximation of the individual masses being mp = 1.54 ± 0.006 M and mc = 1.19 ± 0.011 M,appropriately. These masses, along with the orbital eccentricity, propose that PSR J0453+1559 is a double neutron star system with a mass asymmetry. The anticipated coalescence time due to the outflow of gravitational waves is ∼1.4 x 1012, approximately 100 times greater than the age of the Universe. This is the 10th recognized double neutron star system in the known Universe, and below is its story

Workplace Incivility as Experienced by Hispanic Female Teachers in a South Texas Public High School Led by a Hispanic Female Principal

Workplace incivility is a recent phenomenon and, although much of the research conducted in this area to date has been in organizations other than public schools, incivility in the educational field has been identified as a challenge for teachers due to the mounting pressure experienced by educators. Several studies have shown that women who reach top-level positions are unhelpful to their subordinate female workers, presumably due to their desire to remain unique in their organization and due to the fear of competition. This type of behavior is called the “queen bee effect.” The goal of this qualitative study was to explore the existence of the queen bee syndrome in the public high school setting as displayed by the Hispanic female principal. This study also identified experiences and resiliency approaches employed by the Hispanic female teacher targets to cope with this behavior in the workplace

Essays on Violence-Driven Migration and its Impact on Immigrants’ Origin Countries

Rampant gang-related violence in the Northern Triangle of Central America is increasingly pushing both children and adults to make the risky migration journey to the north. Simultaneously, as a result of the strengthening of U.S. immigration enforcement policies, an increasing number of Central Americans are being repatriated to their countries of origin. This dissertation presents a collection of essays that evaluate the consequences of these migration flows in the country of origin of immigrants providing evidence from El Salvador, a country with nearly one quarter of its population residing abroad and exhibiting one of the highest homicide rates in the world. Chapter 2 advances understanding on the formation, development and consequences of gangs in Central America by bringing together multi-disciplinary evidence. These studies show that gangs are the result of internal conflicts and violence, marginalization, migration, social exclusion, rapid urbanization and lack of economic opportunities for youths, which have existed in these countries for decades. Central American gangs, whose origin can be traced to the U.S. deportation of Salvadorans with a criminal background, grew in power and organization through the implementation of tough-on-crime or \textit{Mano Dura} policies. Gangs are now evidenced to adversely impact the communities they govern by hindering economic and human capital development. Chapter 3 empirically examines how recent deportations of Salvadorans with and without a criminal background impact local gangs and violent crime. This study finds that in municipalities dominated by gangs, the repatriation of Salvadorans without a criminal background leads to an increase in homicides, whereas criminal deportations lead to a reduction in violent crime. These contrasting effects are explained by three main mechanisms: most-serious criminal deportees continue contributing to gang membership and gang-related violence; less-serious criminal deportees have a positive contribution to the local labor market, which decreases their likelihood of re-offending and in turn reduces violent crime; young male non-criminal deportees are becoming the victims of violent crime as they represent the perfect target for gang recruitment. Lastly, Chapter 4 evaluates the impact of parent international migration on educational outcomes of children left behind in El Salvador. This study evidences that children with migrant parents exhibit a lower probability of attending school, where the effect is driven by older boys and girls, ages 13 to 17. Although remittances play an important role in decreasing financial constraints in Salvadoran households, they do not fully compensate for the adverse consequences of parental absence due to migration. As a result, there are labor readjustments within the household where boys are replacing school for work and girls are more prone to be inactive, likely carrying out more housework

Educational Technology Workshops for the Seniors Adults

The City of Watsonville Parks and Community Services works with various ages, from toddlers to seniors, depending on the program or organization. The main focus of this project was to work towards keeping seniors up to date with advanced technology. The problem was that many seniors don’t have the knowledge when it comes to using technology properly. The project\u27s purpose was to educate as many senior citizens with basic computer skills. The workshop was offered both in Spanish and English once every month. The individual appointments are every week on Tuesdays. The project has exceeded expectations. The individual appointments get booked very quickly and the group tech workshop was somewhat successful. Some recommendations for the senior tech workshop was providing more dates available for individual consultations. The individual consultations seem more popular than the group workshops

Pulsar Searching and Timing with the Arecibo and Effelsberg Radio Telescopes

Pulsars are rapidly rotating, highly magnetized, neutron star remnants of the supernova explosions of massive stars. In this thesis, I mostly focus on recycled pulsars, which are old (approx 100 million years old) neutron stars that are descendants from close, interacting binary systems. They have extraordinary rotational stability due to being spun-up (recycled) to fast spin periods (few to tenths of milliseconds) by accretion of mass and angular momentum from their companion star. Their extreme properties have made them fundamental tools for a broad range of applications, including the study of ultra-dense matter, the tests of relativistic theories of gravity, and the search for low-frequency gravitational waves. I will present the discovery and follow-up of PSR J04531559 and PSR J1411+2551, which both are double neutron star systems (DNS). DNS are rare systems of which two massive stars orbit each other their entire life and survived each other's explosive supernova deaths leaving behind two neutron stars in an eccentric orbit. PSR J0453+1559 is the first asymmetric DNS that has a pulsar mass of 1.559(5) solar masses and the mass of the companion is 1.174(4) solar masses, the lightest precise neutron star mass measurement as of today. PSR J1411+2551 is among one of the lightest total mass systems from all the known DNS population, that could leave behind a massive neutron star after its merger event. Additionally, I will present other 6 recycled pulsars, five which are in a binary and one isolated millisecond pulsar

Campyloneurum angustifolium, a new Polypodiaceae record for Argentina

Campyloneurum angustifolium (Sw.) Fée (Polypodiaceae) es un nuevo registro para la flora Argentina. El género tiene seis especies conocidas para el noroeste argentino. Se presentan una descripción, ilustraciones y fotografías de la planta, así como un mapa y una clave para las especies de Campyloneurum que crecen en el noroeste argentino.Campyloneurum angustifolium (Sw.) Fée (Polypodiaceae) is a new record for Argentina. A description and illustrations are provided, as well as a map and a key of Campyloneurum species from northwestern Argentina.Fil: Jaimez, Dalma Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Bio y Geociencias del NOA. Universidad Nacional de Salta. Facultad de Ciencias Naturales. Museo de Ciencias Naturales. Instituto de Bio y Geociencias del NOA; ArgentinaFil: Martinez, Olga Gladys. Universidad Nacional de Jujuy. Instituto de Ecorregiones Andinas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Salta. Instituto de Ecorregiones Andinas; Argentina. Universidad Nacional de Salta; Argentin

Género y gobiernos municipales. El caso de Villa Guerrero, Estado de México (2003-2006)

Este documento analiza algunas causas que obstaculizan la representación femenina en la toma de decisiones de los gobiernos municipales mexicanos. Para ello, utiliza el enfoque de género que permite explicar la inequidad social y política entre mujeres y hombres así como sus consecuencias. En un segundo momento, presenta un estudio de caso que refiere los obstáculos socioculturales que enfrentó una alcaldesa para lograr el triunfo en un contexto con hegemonía política masculina