28 research outputs found

    IPHAS and the symbiotic stars. I. Selection method and first discoveries

    Full text link
    The study of symbiotic stars is essential to understand important aspects of stellar evolution in interacting binaries. Their observed population in the Galaxy is however poorly known, and is one to three orders of magnitudes smaller than the predicted population size. IPHAS, the INT Photometric Halpha survey of the Northern Galactic plane, gives us the opportunity to make a systematic, complete search for symbiotic stars in a magnitude-limited volume, and discover a significant number of new systems. A method of selecting candidate symbiotic stars by combining IPHAS and near-IR (2MASS) colours is presented. It allows us to distinguish symbiotic binaries from normal stars and most of the other types of Halpha emission line stars in the Galaxy. The only exception are T Tauri stars, which can however be recognized because of their concentration in star forming regions. Using these selection criteria, we discuss the classification of a list of 4338 IPHAS stars with Halpha in emission. 1500 to 2000 of them are likely to be Be stars. Among the remaining objects, 1183 fulfill our photometric constraints to be considered candidate symbiotic stars. The spectroscopic confirmation of three of these objects, which are the first new symbiotic stars discovered by IPHAS, proves the potential of the survey and selection method.Comment: Accepted for publication on Astronomy and Astrophysics. 12 pages, 8 figure

    Efectos de la fibra dietética en la reducción de factores de riesgo cardiovasculares asociados a la obesidad

    Get PDF
    La obesidad es una pandemia que afecta a más de 650 millones de personas en todo el mundo. Los principales efectos del aumento y la acumulación de grasa corporal son la resistencia a la insulina, la dislipidemia y la hipertensión, los cuales son factores de riesgo para presentar enfermedades cardiovasculares. Por lo tanto, una de las terapias nutricionales para revertir estas alteraciones es el consumo de fibra dietética, que al evadir la digestión por enzimas humanas y la absorción intestinal, tienen efectos en todo el tracto digestivo disminuyendo la absorción de macronutrientes, aumentando la saciedad y modificando la microbiota intestinal. Por lo mencionado anteriormente, la presente revisión tiene como objetivo describir los efectos de la fibra dietética en la reducción de los factores de riesgo cardiovasculares asociados a la obesidad. Para el desarrollo de tal objetivo describiremos los factores de riesgo mencionados. Asimismo, describiremos la fibra dietética y los mecanismos implicados en la reducción de dichos factores. Palabras claves: Fibra dietética, enfermedades cardiovasculares y obesidad (DeCS). DOI: http://dx.doi.org/10.17268/rmt.2021.v16i02.0

    Extinction risk of Mesoamerican crop wild relatives

    Get PDF
    Ensuring food security is one of the world's most critical issues as agricultural systems are already being impacted by global change. Crop wild relatives (CWR)—wild plants related to crops—possess genetic variability that can help adapt agriculture to a changing environment and sustainably increase crop yields to meet the food security challenge. Here we report the results of an extinction risk assessment of 224 wild relatives of some of the world's most important crops (i.e. chilli pepper, maize, common bean, avocado, cotton, potato, squash, vanilla and husk tomato) in Mesoamerica—an area of global significance as a centre of crop origin, domestication and of high CWR diversity. We show that 35% of the selected CWR taxa are threatened with extinction according to The International Union for Conservation of Nature (IUCN) Red List demonstrates that these valuable genetic resources are under high anthropogenic threat. The dominant threat processes are land use change for agriculture and farming, invasive and other problematic species (e.g. pests, genetically modified organisms) and use of biological resources, including overcollection and logging. The most significant drivers of extinction relate to smallholder agriculture—given its high incidence and ongoing shifts from traditional agriculture to modern practices (e.g. use of herbicides)—smallholder ranching and housing and urban development and introduced genetic material. There is an urgent need to increase knowledge and research around different aspects of CWR. Policies that support in situ and ex situ conservation of CWR and promote sustainable agriculture are pivotal to secure these resources for the benefit of current and future generations
    corecore