Oxygen, the Janus gas; its effects on human placental development and function

The accumulation of oxygen in the earth's atmosphere enabled metabolic pathways based on high-energy electron transfers that were capable of sustaining complex multicellular organisms to evolve. This advance came at a price, however, for the high reactivity of oxygen posed a major challenge as biological molecules became susceptible to oxidative damage, resulting in potential loss of function. Many extant physiological systems are therefore adapted, and homeostatically regulated, to supply sufficient oxygen to meet energy demands whilst also protecting cells, and mitochondria in particular, from excessive concentrations that could lead to oxidative damage. The invasive form of implantation displayed by the human conceptus presents particular challenges in this respect. During the first trimester, the conceptus develops in a low oxygen environment that favours organogenesis in the embryo, and cell proliferation and angiogenesis in the placenta. Later in pregnancy, higher oxygen concentrations are required to support the rapid growth of the fetus. This transition, which appears unique to the human placenta, must be negotiated safely for a successful pregnancy. Normally, onset of the maternal placental circulation is a progressive periphery-centre phenomenon, and is associated with extensive villous regression to form the chorion laeve. In cases of miscarriage, onset of the circulation is both precocious and disorganized, and excessive placental oxidative stress and villous regression undoubtedly contribute to loss of the pregnancy. Comparison of experimental and in vivo data indicates that fluctuations in placental oxygen concentration are a more powerful stimulus for the generation of oxidative stress than chronic hypoxia alone. Placental oxidative and endoplasmic reticulum stress appear to play key roles in the pathophysiology of complications of pregnancy, such as intrauterine growth restriction and preeclampsia, through their adverse impacts on placental function and growth. Establishing an inviolable maternal blood supply for the second and third trimesters is therefore one of the most crucial aspects of human placentation

On playing well in a sum of games

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engieering and Computer Science, 1985.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERING.Bibliography: leaves 84-86.by Laura Jo Yedwab.M.S

Las dimensiones de la actividad laboral y la satisfacción con el trabajo y con la vida: el caso de México

In this paper we evaluate the impact that a specific area in individuals’ lives- their job or occupation – has over their satisfaction with life in general and specifically with their labor activity. We analyze the working life of the participants in the labor force in Mexico on the basis of four fundamental dimensions: sector of employment (formal sector/informal sector), type of employment (formal employment/informal employment), relation with the means of production (owners/employees), and type of activity (white collar/blue collar). With data from the National Survey of Household Expenditure (ENGASTO) carried out in 2012 by the Statistics National Institute (INEGI), we found that - controlling for income, age, education and other relevant variables – working in the formal sector as well as being formally employed have a positive impact over the level of satisfaction with life and with work; being self-employed impacts negatively on both types of satisfaction, while being a white or blue collar participant in the work force, does not significantly influence life or work satisfaction.En este trabajo, investigamos el impacto que un área específica de la vida de los individuos, su trabajo u ocupación, tiene sobre su nivel de satisfacción con la vida y con el trabajo en particular. Analizamos la actividad laboral de los participantes en la fuerza de trabajo en México con base en cuatro de sus dimensiones fundamentales: sector de empleo (formal/informal); tipo de empleo (formal/informal); relación con los medios de producción (auto-empleado/subordinado) y tipo de actividad (cuello blanco/cuello azul). Con datos de la Encuesta Nacional de Gasto de los Hogares (ENGASTO) realizada por el INEGI en 2012, encontramos que –controlando por ingreso, edad, educación y otras variables relevantes- trabajar en el sector formal y tener un empleo formal tienen un impacto positivo sobre la satisfacción con la vida y con el trabajo; mientras que ser empleador impacta negativamente en estos dos tipos de satisfacción y el tipo de actividad que se realiza no incide significativamente en el bienestar subjetivo de los trabajadores

The network structure of women's studies: An analysis of Psychology Women Quarterly

Bibliometric analysis of the journa

Tipos de participación política y bienestar subjetivo: Un estudio mundial

Subjective well-being has been described as perhaps “the ultimate dependent variable” of the social sciences. Thus, it is understandable that much of the empirical research on the subject has focused on the identification of its correlates. In this paper we utilize the sixth wave of the World Value Survey carried out in sixty countries between 2010 and 2014, to evaluate the relationship between different types of political participation and the subjective well-being of citizens, Our research partially confirms the hypothesis that, when controlling for the democratic or undemocratic character of political institutions, conventional political participation is positively and significantly associated with life satisfaction, while unconventional conflictive political activities show the opposite relationship to well-being. On the other hand, the democratic nature of state institutions is universally and consistently related to higher levels of personal well-being among individuals.El bienestar subjetivo ha sido descrito como, tal vez, “la variable dependiente fundamental” de las ciencias sociales, por lo cual no resulta sorpresivo que una buena parte de la literatura empírica sobre el tema se ha enfocado en identificar sus correlatos. En este trabajo evaluamos la relación entre distintos tipos de participación política y bienestar subjetivo utilizando la sexta ola de la Encuesta Mundial de Valores para sesenta países levantada entre 2010 y 2014. Nuestros resultados sugieren que, controlando por el grado de libertad de los diferentes países, existen diferencias sustantivas en la fuerza y dirección de la asociación entre distintos tipos de participación política y el bienestar subjetivo de los ciudadanos. Nuestra investigación confirma parcialmente la hipótesis de que formas convencionales de participación se asocian de manera significativa y positiva con la satisfacción individual con la vida, mientras las formas menos convencionales y más conflictivas, muestran una relación opuesta. Por otra parte, la naturaleza democrática de las instituciones, está universal y consistentemente asociada a mayores niveles de bienestar subjetivo de los individuos