High-intensity light promotes adaptive divergence of photosynthetic traits between sun-exposed and shaded populations in Saxifraga fortunei.

PREMISE: Light is essential for plants, and local populations exhibit adaptive photosynthetic traits depending on their habitats. Although plastic responses in morphological and/or physiological characteristics to different light intensities are well known, adaptive divergence with genetic variation remains to be explored. This study focused on Saxifraga fortunei (Saxifragaceae) growing in sun-exposed and shaded habitats. METHODS: We measured the leaf anatomical structure and photosynthetic rate of plants grown in their natural habitats and in a common greenhouse (high- and low-intensity light experimental sites). To assess differences in ecophysiological tolerance to high-intensity light between the sun and shade types, we evaluated the level of photoinhibition of photosystem II and the leaf mortality rate under high-intensity light conditions. In addition, population genetic analysis was conducted to investigate phylogenetic origins. RESULTS: Clear phenotypic differences were found between the sun and shade types despite their recent phylogenetic origin. The leaf anatomical structure and photosynthetic rate showed plastic changes in response to growing conditions. Moreover, the sun type had a well-developed palisade parenchyma and a higher photosynthetic rate, which were genetically fixed, and a lower level of photoinhibition under high-intensity light. CONCLUSIONS: Our findings demonstrate that light intensity is a selective pressure that can rapidly promote phenotypic divergence between the sun and shade types. While phenotypic changes in multiple photosynthetic traits were plastic, genetic divergence in specific traits related to adaptation to high-intensity light would be fundamental for ecotypic divergence to different light regimes.

The COSPAR planetary protection policy for missions to Icy Worlds: A review of history, current scientific knowledge, and future directions.

Recent discoveries related to the habitability and astrobiological relevance of the outer Solar System have expanded our understanding of where and how life may have originated. As a result, the Icy Worlds of the outer Solar System have become among the highest priority targets for future spacecraft missions dedicated to astrobiology-focused and/or direct life detection objectives. This, in turn, has led to a renewed interest in planetary protection concerns and policies for the exploration of these worlds and has been a topic of discussion within the COSPAR (Committee on Space Research) Panel on Planetary Protection. This paper summarizes the results of those discussions, reviewing the current knowledge and the history of planetary protection considerations for Icy Worlds as well as suggesting ways forward. Based on those discussions, we therefore suggest to (1) Establish a new definition for Icy Worlds for Planetary Protection that captures the outer Solar System moons and dwarf planets like Pluto, but excludes more primitive bodies such as comets, centaurs, and asteroids: Icy Worlds in our Solar System are defined as all bodies with an outermost layer that is believed to be greater than 50 % water ice by volume and have enough mass to assume a nearly round shape. (2) Establish indices for the lower limits of Earth life with regards to water activity (LLAw) and temperature (LLT) and apply them into all areas of the COSPAR Planetary Protection Policy. These values are currently set at 0.5 and -28 °C and were originally established for defining Mars Special Regions; (3) Establish LLT as a parameter to assign categorization for Icy Worlds missions. The suggested categorization will have a 1000-year period of biological exploration, to be applied to all Icy Worlds and not just Europa and Enceladus as is currently the case. (4) Have all missions consider the possibility of impact. Transient thermal anomalies caused by impact would be acceptable so long as there is less than 10-4 probability of a single microbe reaching deeper environments where temperature is >LLT in the period of biological exploration. (5) Restructure or remove Category II* from the policy as it becomes largely redundant with this new approach, (6) Establish that any sample return from an Icy World should be Category V restricted Earth return.

Chapter 7: Assessing Habitability Beyond Earth.

All known life on Earth inhabits environments that maintain conditions between certain extremes of temperature, chemical composition, energy availability, and so on (Chapter 6). Life may have emerged in similar environments elsewhere in the Solar System and beyond. The ongoing search for life elsewhere mainly focuses on those environments most likely to support life, now or in the past-that is, potentially habitable environments. Discussion of habitability is necessarily based on what we know about life on Earth, as it is our only example. This chapter gives an overview of the known and presumed requirements for life on Earth and discusses how these requirements can be used to assess the potential habitability of planetary bodies across the Solar System and beyond. We first consider the chemical requirements of life and potential feedback effects that the presence of life can have on habitable conditions, and then the planetary, stellar, and temporal requirements for habitability. We then review the state of knowledge on the potential habitability of bodies across the Solar System and exoplanets, with a particular focus on Mars, Venus, Europa, and Enceladus. While reviewing the case for the potential habitability of each body, we summarize the most prominent and impactful studies that have informed the perspective on where habitable environments are likely to be found.

Chapter 9: Life as We Don't Know It.

While Earth contains the only known example of life in the universe, it is possible that life elsewhere is fundamentally different from what we are familiar with. There is an increased recognition in the astrobiology community that the search for life should steer away from terran-specific biosignatures to those that are more inclusive to all life-forms. To start exploring the space of possibilities that life could occupy, we can try to dissociate life from the chemistry that composes it on Earth by envisioning how different life elsewhere could be in composition, lifestyle, medium, and form, and by exploring how the general principles that govern living systems on Earth might be found in different forms and environments across the Solar System. Exotic life-forms could exist on Mars or Venus, or icy moons like Europa and Enceladus, or even as a shadow biosphere on Earth. New perspectives on agnostic biosignature detection have also begun to emerge, allowing for a broader and more inclusive approach to seeking exotic life with unknown chemistry that is distinct from life as we know it on Earth.

Chapter 3: The Origins and Evolution of Planetary Systems.

The materials that form the diverse chemicals and structures on Earth-from mountains to oceans and biological organisms-all originated in a universe dominated by hydrogen and helium. Over billions of years, the composition and structure of the galaxies and stars evolved, and the elements of life, CHONPS, were formed through nucleosynthesis in stellar cores. Climactic events such as supernovae and stellar collisions produced heavier elements and spread them throughout the cosmos, often to be incorporated into new, more metal-rich stars. Stars typically form in molecular clouds containing small amounts of dust through the collapse of a high-density core. The surrounding nebular material is then pulled into a protoplanetary disk, from which planets, moons, asteroids, and comets eventually accrete. During the accretion of planetary systems, turbulent mixing can expose matter to a variety of different thermal and radiative environments. Chemical and physical changes in planetary system materials occur before and throughout the process of accretion, though many factors such as distance from the star, impact history, and level of heating experienced combine to ultimately determine the final geophysical characteristics. In Earth's planetary system, called the Solar System, after the orbits of the planets had settled into their current configuration, large impacts became rare, and the composition of and relative positions of objects became largely fixed. Further evolution of the respective chemical and physical environments of the planets-geosphere, hydrosphere, and atmosphere-then became dependent on their local geochemistry, their atmospheric interactions with solar radiation, and smaller asteroid impacts. On Earth, the presence of land, air, and water, along with an abundance of important geophysical and geochemical phenomena, led to a habitable planet where conditions were right for life to thrive.

Organic Input to Titan's Subsurface Ocean Through Impact Cratering.

Titan has an organic-rich atmosphere and surface with a subsurface liquid water ocean that may represent a habitable environment. In this work, we determined the amount of organic material that can be delivered from Titan's surface to its ocean through impact cratering. We assumed that Titan's craters produce impact melt deposits composed of liquid water that can founder in its lower-density ice crust and estimated the amount of organic molecules that could be incorporated into these melt lenses. We used known yields for HCN and Titan haze hydrolysis to determine the amount of glycine produced in the melt lenses and found a range of possible flux rates of glycine from the surface to the subsurface ocean. These ranged from 0 to 1011 mol/Gyr for HCN hydrolysis and from 0 to 1014 mol/Gyr for haze hydrolysis. These fluxes suggest an upper limit for biomass productivity of ∼103 kgC/year from a glycine fermentation metabolism. This upper limit is significantly less than recent estimates of the hypothetical biomass production supported by Enceladus's subsurface ocean. Unless biologically available compounds can be sourced from Titan's interior, or be delivered from the surface by other mechanisms, our calculations suggest that even the most organic-rich ocean world in the Solar System may not be able to support a large biosphere.

História e memória de vidro: as fotografias brasileiras do eclipse de 1919 em Sobral / History and memory on glass: the Brazilian photographs of the 1919 eclipse in Sobral

Resumo O objetivo do artigo é divulgar as fotografias astronômicas feitas pela expedição brasileira enviada a Sobral para registrar o eclipse total do Sol de 29 de maio de 1919. Uma rica coleção de fotografias, na maioria inéditas, disponíveis em suporte de placas de vidro, encontra-se na Biblioteca do Observatório Nacional. A fotografia ocupou lugar central na astronomia do século XX. O eclipse de Sobral ganhou repercussão mundial devido à comprovação da teoria da relatividade geral pelas expedições inglesas. Neste texto ressaltamos a participação dos astrônomos do Observatório Nacional no evento, pois foram os primeiros brasileiros a ter sucesso na obtenção de fotografias da coroa solar.

Abstract The objective of this article is to disseminate the astronomical photographs taken by the Brazilian expedition sent to Sobral (state of Ceará) to record the total eclipse of the Sun on May 29, 1919. There is a rich collection of photographs, most unpublished, available on glass plates stored in the Library of the Observatório Nacional. Photography was central to astronomy in the twentieth century. Thus, while the eclipse in Sobral had worldwide repercussions due to the proof of the theory of general relativity by the English expeditions, in this article we highlight the participation of astronomers from the Observatório Nacional at the same event, since they were the first Brazilians to successfully obtain photographs of the Sun's corona.

Taxonomías digitales: fundamentos teóricos y metodología de construcción / Digital taxonomies: theoretical fundamentals and construction methodology

Resumen El artículo analiza las taxonomías digitales desde la perspectiva bibliotecológica. Su objetivo fue construir una taxonomía digital del área de conocimiento "Sistema solar" que pudiera ser implementada como sistema de acceso temático jerárquico-visual para un conjunto de recursos de información digitales albergados en un sitio web. La metodología empleada en la construcción de la taxonomía consistió en una propuesta particular que se nutre de dos metodologías relevantes sobre el tema. Se encontró que las taxonomías son un Sistema para la Organización del Conocimiento (SOC) que, debido a su potencial representador y organizador, han migrado al espacio de los Sistemas para la Organización del conocimiento en Red (SOCR) cuyas funciones en la web están asociadas, entre muchas aplicaciones, a la indización y clasificación de recursos de información. Se concluye que el conocimiento teórico y aplicado de las taxonomías digitales es prioritario para los profesionales de la información que día a día se enfrentan a más retos relacionados con el ordenamiento de recursos de información insertos en la World Wide Web.

Abstract The article analyzes digital taxonomies from the librarianship perspective. Its objective was to build a digital taxonomy about "Solar System" knowledge area that can be implemented as hierarchical-visual subject access system for a set of digital information resources stored in a website. The methodology used to build the taxonomy was a proposal based on two relevant methodologies about the topic. It was found that taxonomies are a Knowledge Organization Systems (KOS) that, due to its representational and organizer potential, have migrated to the space of Networked Knowledge Organization Systems (NKOS), whose tasks on the web are associated, among many applications, to the indexing and classification of information resources. It is concluded that the theoretical and applied knowledge of digital taxonomies is a priority for information professionals who every day deals with challenges related to the organization of information sources inserted in the World Wide Web.

Astrobiología, el origen de la vida y el cambio global / Astrobiology, the origin of life and global change

En 1996, la Administración Nacional de Aeronáutica y Espacio de los Estados Unidos (NASA) invitó a la comunidad científica a crear un Instituto de Astrobiología. El primer taller sobre el tema se realizó en NASA Ames y marcó el comienzo oficial de esta rama de la ciencia que tiene sus raíces en la Exobiología de los Estados Unidos y la Biología Cósmica de la ex Unión Soviética. En el nuevo concepto, las Ciencias de la Tierra tienen una presencia mayor y se pone el acento en el enfoque interdisciplinario. En otros tralleres se analizaron los méritos de los componentes a incluir en el "mapa de ruta" de la Astrobiología. El taller organizado por Carlos Lasta y colaboradores en Mar del Plata (1999) analizó las costas y estuarios como colectores de señales complejas de ecosistemas continentales y trató varias facetas de la actividad humana y el cambio ambiental. Hoy la Astrobiología trata de responder las siguientes preguntas: ¿Cómo comienza y evoluciona la vida? ¿Existe vida en otros lugares del universo? ¿Cuál es el futuro de la vida en la Tierra y más allá? Algunas evidencias recientes sumadas al desarrollo de la Bioquímica y Biología Molecular estimulan la formulación de hipótesis sobre el origen espontáneo, el de un antecesor común muy simple y aun desconocido, o su procedencia desde el espacio exterior. La emergencia de la vida cambió la composición química de la armósfera con la inyección de oxígeno, producto de la fotosintesis, y enseguida formó la capa de ozono estratosférico que cambió las condiciones para la vida en la tierra facilitando la colonización de los continentes. Las etapas más recientes de la historia humana introdujeron otra clase de cambio. En 1896 el químico sueco Svante Arrhenius predijo que la temperatura global de la Tierra ascendería varios grados si la concentración de dióxido de carbono (CO2) en la atmósfera se duplica. El CO2 y otros gases transparentes a la luz y opacos al calor producen el efecto invernadero...

Secador solar móvil de estructura metálica para plantas medicinales / Mobile solar dryer of metallic structure for medicinal plants

En el presente trabajo se evaluaron los resultados de los estudios realizados en el secador solar móvil de estructura metálica construido con materiales de desecho en la Estación Experimental de Plantas Medicinales ôDr. Juan Tomás Roigö. Las especies con las que se realizaron los experimentos fueron: Plantago lanceolata L. (llantén menor), Plantago major L. (llantén), Calendula officinalis L. (caléndula), Matricaria recutita L. (manzanilla), Ocimum basilicum L. (albahaca). La droga obtenida en el equipo no se diferenció apreciablemente de la secada en tamices colocados paralelamente al sol, mantuvo en todos los casos su color y olor característicos, así como presentó que los índices farmacognósticos determinados se encontraban dentro de los rangos permisibles establecidos en las normas de calidad para su comercialización. Se comprobó además que el equipo es altamente productivo y rentable

Tratamento nao medicamentoso, profilatico e prognostico da osteoporose / Alternative treatment, profilatic and prognostic of osteoporosis

A osteoporose e um problema de saude publica que tende a crescer com o aumento da longevidade e que merece atencao especial para melhorar a morbidade e qualidade de vida. O tratamento nao medicamentoso representado por exercicios e suplementacao alimentar com calcio, vitamina D e fluor constituem medidas profilaticas de comprovada eficacia. O prognostico da osteoporose reveste-se de importancia, sendo fornecido pelo...

La lógica de una de las creencias tradicionales en salud: eclipse y embarazo en Ocuituco, México / The logic of a traditional health belief: eclipse and pregnancy in Ocuituco, Mexico

Se presenta un análisis de la lógica de una de las creencias tradicionales en salud más comunes en el ámbito rural mexicano, a partir de testimonios recogidos en la zona de Ocuituco, Morelos, México; la creencia se refiere al peligro que corre una mujer embarazada si se expone directamente a un eclipse de sol, o a la luna llena. Se discute la importancia que, desde la perspectiva de la investigación en salud pública, representa conocer la lógica que subyace a estas creencias, pues éstas se asocian a formas específicas de sufrimiento y, a su vez, dan lugar a conductas preventivas determinadas, que es importante tomar en cuenta si se busca incrementar la eficiencia de los programas de salud. Se discute la interrelación de otros elementos tradicionales (tales como la enfermedad "pérdida de la sombra" y la "teoría de lo frío-caliente") con esta creencia y se analizan algunas de las interpretaciones que se han formulado en torno a ella, y que han buscado vincular la pérdida de la sombra con la creencia del eclipse. Finalmente, se propone una interpretación alternativa a las existentes, a partir de una propuesta metodológica de tipo estructuralista. Esta interpretación se apoya en el mito náhuatl de la creación del sol y de la luna, y en información provista en fuentes historicas acerca de la naturaleza de los conejos dentro de aquella cultura. Se propone que la creencia sobre el eclipse debe vincularse a la teoría de lo "frío-caliente" pero no a la "pérdida de la sombra". El artículo concluye haciendo énfasis en la importancia de este tipo de investigaciones dentro del campo de la salud pública, pues a través de ellas es posible, por una parte, comprender la lógica que subyace a este tipo de concepciones y, por otra, reforzar el diálogo entre la medicina moderna y las medicinas alternativas; esto es, facilitar el encuentro que entre ambas tiene lugar todos los días en diversas comunidades del país

An analysis of the logic of one of the commonest health beliefs in rural areas of Mexico is made, taking as a starting point testimonies collected in the area of Ocuituco, in the state of Morelos. This belief suggests that a pregnant woman is in danger of having a harelipped baby during a solar eclipse. The importance of the knowledge about the logic of this kind of beliefs is discussed from a public health perspective. These beliefs are associated with specific forms of suffering and give way to particular preventive measures which must be taken into account if the efficacy of health programs is to be increased. The interrelation of these beliefs with other traditional elements (such as the "loss of the shadow" and the "hot-cold theory") is discussed. Also, some of the already existing interpretations of this belief which seek to link the "loss of the shadow" with the solar eclipse belief are reviewed. Finally, an alternative interpretation of this belief is made from a structuralist methodological perspective. This interpretation is grounded in the Nahuatl myth on the creation of the sun and the moon, and in an analysis of the nature of rabbits in the Nahuatl culture, according to historic secondary sources. It is suggested that the belief about the danger of a solar eclipse must be interpreted in connection to the "hot-cold theory", but not to the "loss of the shadow". This paper concludes by emphasizing the importance of this type of research within the public health field, as it enables us both to understand the underlying logic of this type of conceptions, and to reinforce the dialogue between modern and alternative medicine, so that the daily encounter between these two types of medicine can be facilitated.

Conductas de reposo (letargo) de los macacos cola de muñón (Macaca arctoides) en cautiverio, causadas por un eclipse solar / Resting (lethargic) behaviors of captive stumptail macaca (Macaca arctoides) caused by a colar eclipse

Se estudió la influencia de un eclipse total del sol (México, 11 de julio de 1991) sobre el comportamiento de un grupo de macacos cola de muñón (M. arctoides) que viven en cautiverio exterior. Se empleó un grupo heterosexual de nueve monos de diferentes edades y cada sujeto sirvió como su propio control. Los animales fueron filmados durante aproximadamente una hora continua el día del eclipse (de 1300 a 1405 h), para comparar sus reacciones conductuales con aquellas observadas durante el anochecer y amanecer en días veraniegos ordinarios (de 19:00 h de un día a las 06:00 h del día siguiente). Durante la fase de totalidad del eclipse (13:20 h), los animales formaron un solo grupo y ascendieron lentamente a la plataforma superior dentro del área de vivienda. Este lugar fue el sitio principal para dormir durante los días de control. Mostraron conductas de búsqueda grupal de abrigo, disminuyó la actividad motora y guardaron absoluto silencio. Conforme finalizó el eclipse, la actividad general volvió a la normalidad. Las reacciones conductuales fueron iniciadas por una hembra juvenil, incluyendo una conducta atípica de exploración. Los resultados sugieren que el cambio en el nivel de iluminación fue el factor principal que afectó la conducta de los primates, lo que confirma la dependencia fotoperiódica de sus sistemas circadianos de reposo

Seasonal variation in the orientation of homing pigeons: new evidence for a latency in the sun compass

Homing pigeons must keep track of the seasonal variations in the sun's daily motion to use the sun as a reference. A delay of seven weeks in such updating of their ephemerides was previously interpreted as being the cause of the behavior of control pigeons studied near the equator in September, when birds released in the morning flew anomalously to the right of birds released in the afternoon. Demonstration of the chronic existence of a delay was obtained by observing that the anomaly was still present but inverted in sign in March, when the pigeons released in the morning flew to the left of those released in the afternoon