Academic literature on the topic 'Gaia hypothesis'
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Journal articles on the topic "Gaia hypothesis"
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Clarke, Bruce. "Rethinking Gaia: Stengers, Latour, Margulis." Theory, Culture & Society 34, no. 4 (January 17, 2017): 3–26. http://dx.doi.org/10.1177/0263276416686844.
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At its inception innocent of philosophical or metaphysical designs, the Gaia hypothesis of James Lovelock and Lynn Margulis was soon liberated from the precincts of scientific cultivation to enter into cultural free association. Nonetheless, scientific and scholarly attention and debate have long precipitated a bona fide discourse of Gaia theory. Moreover, intellectually serious extra-scientific figures of Gaia have also been on the rise in the last decade. This essay treats a selection of these newer Gaian figures, specifically, Isabelle Stengers’s Gaia the Intruder and Bruno Latour’s secular Gaia, in relation to Lovelock’s Gaia and Lynn Margulis’s evocations of autopoietic Gaia. When nuanced through second-order systems theory, the discourse of autopoietic Gaia satisfies Stengers’s and Latour’s demands for a non-holistic, heterogeneous yet coherent Gaia concept fit for communicative efficacy in the so-called Anthropocene epoch.
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Alcabes, Olivia D. N., Stephanie Olson, and Dorian S. Abbot. "Robustness of Gaian feedbacks to climate perturbations." Monthly Notices of the Royal Astronomical Society 492, no. 2 (January 11, 2020): 2572–77. http://dx.doi.org/10.1093/mnras/staa055.
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ABSTRACT The Gaia hypothesis postulates that life regulates its environment to be favorable for its own survival. Most planets experience numerous perturbations throughout their lifetimes such as asteroid impacts, volcanism, and the evolution of their host star’s luminosity. For the Gaia hypothesis to be viable, life must be able to keep the conditions of its host planet habitable, even in the face of these challenges. ExoGaia, a model created to investigate the Gaia hypothesis, has been previously used to demonstrate that a randomly mutating biosphere is in some cases capable of maintaining planetary habitability. However, those model scenarios assumed that all non-biological planetary parameters were static, neglecting the inevitable perturbations that real planets would experience. To see how life responds to climate perturbations to its host planet, we created three climate perturbations in ExoGaia: one rapid cooling of a planet and two heating events, one rapid and one gradual. The planets on which Gaian feedbacks emerge without climate perturbations are the same planets on which life is most likely to survive each of our perturbation scenarios. Biospheres experiencing gradual changes to the environment are able to survive changes of larger magnitude than those experiencing rapid perturbations, and the magnitude of change matters more than the sign. These findings suggest that if the Gaia hypothesis is correct, then typical perturbations that a planet would experience may be unlikely to disrupt Gaian systems.
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Crosby, Sarah L. "Gaia Again // De nuevo Gaia." Ecozon@: European Journal of Literature, Culture and Environment 7, no. 1 (June 15, 2016): 228–33. http://dx.doi.org/10.37536/ecozona.2016.7.1.996.
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Book review of Toby Tyrrell's On Gaia: A Critical Investigation of the Relationship between Life and Earth and of Michael Ruse's The Gaia Hypothesis: Science on a Pagan Planet. Resumen Reseña de On Gaia: A Critical Investigation of the Relationship between Life and Earth de Tyrrell y de The Gaia Hypothesis: Science on a Pagan Planet de Michael Ruse.
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Mészáros, E. "Gaia hypothesis and atmospheric aerosol." Acta Physica Hungarica 65, no. 2-3 (June 1989): 343–47. http://dx.doi.org/10.1007/bf03156081.
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Lovelock, James E. "Hands up for the Gaia hypothesis." Nature 344, no. 6262 (March 1990): 100–102. http://dx.doi.org/10.1038/344100a0.
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Baerlocher, F. "The Gaia hypothesis: A fruitful fallacy?" Experientia 46, no. 3 (March 1990): 232–38. http://dx.doi.org/10.1007/bf01951752.
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Craik, J. C. A. "The Gaia Hypothesis - Fact or Fancy?" Journal of the Marine Biological Association of the United Kingdom 69, no. 4 (November 1989): 759–68. http://dx.doi.org/10.1017/s0025315400032136.
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Many large-scale properties of the biosphere are affected or determined by the activities of living organisms and are maintained at remarkably constant values over long periods. For example, the oxygen content of the atmosphere appears to have been maintained near its present value for hundreds of millions of years, despite the rapid flux of oxygen between production by plants and consumption by animals and decomposing microorganisms. (In this article, I shall use 'biosphere' to denote the whole of the concentric shell of the planet Earth which holds life, and 'biota' to mean all living organisms. Others have sometimes used 'biosphere' to mean the latter.) Lovelock was the first to show clearly how the composition of the Earth's atmosphere, unlike that of Mars or Venus, was held well away from thermodynamic equilibrium by the activities of living organisms (Lovelock, 1983). Other biospheric properties, such as temperature and oceanic pH and salinity, have similarly remained fairly constant despite the existence of large perturbing influences (Lovelock, 1979).
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Moody, David E. "Seven misconceptions regarding the Gaia hypothesis." Climatic Change 113, no. 2 (December 17, 2011): 277–84. http://dx.doi.org/10.1007/s10584-011-0382-4.
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Kovalenko, A. G. "“Gaia hypothesis”, or “Science of curse”." RUDN Journal of Sociology 23, no. 2 (June 30, 2023): 384–88. http://dx.doi.org/10.22363/2313-2272-2023-23-2-384-388.
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The article is a review of the book by A. Etkind, which is based on the data of sociology, history, economics, political science and statistics: the author describes the relationship between raw materials and humankind to suggest a way out of the dramatic collision ( The Nature of Evil. Raw Materials and the State . Moscow: New Literary Review, 2023. 504 p.). The second edition of the book confirms the relevance of its agenda in the contemporary situation. The chronological framework of the book covers the history from antiquity to the present day: the author shows how the key raw materials changed from timber and grain in the past to oil and gas in the present, and how such changes affected not only tastes and lifestyle but also political systems and economic vectors, which, in turn, had the opposite effect on the choice of raw materials. The author argues that the desire to possess raw materials and the intensity of their extraction and processing determined the geopolitical interests of the states, led to wars and, ultimately, to new state borders. The author introduces the concept “addictivity of raw materials” in the life of the individual and societies, which implies an unjustified dependence on a certain type of raw materials (sugar, tobacco, opium or oil), and this dependence led to global disproportions and changed the ‘natural’ historical process.
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Rubin, Sergio, and Michel Crucifix. "Taking the Gaia hypothesis at face value." Ecological Complexity 49 (March 2022): 100981. http://dx.doi.org/10.1016/j.ecocom.2022.100981.
Full textDissertations / Theses on the topic "Gaia hypothesis"
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Jacobs, Liza. "Gaia : an analysis of the critical literature with an emphasis on the philosophical and spiritual implications of the hypothesis." Title page, table of contents and abstract only, 1991. http://web4.library.adelaide.edu.au/theses/09ENV/09envj17.pdf.
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Meyers, Amanda. "The interrelationships of nature based on Thoreau's Walden and Lovelock's Gaia hypothesis." Thesis, This resource online, 1994. http://scholar.lib.vt.edu/theses/available/etd-06112009-063601/.
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Lana, Celaya María Aránzazu. "Marine aerosols, their precursors and their influence on clouds over the global ocean." Doctoral thesis, Universitat Politècnica de Catalunya, 2012. http://hdl.handle.net/10803/83367.
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Marine aerosols have a large potential to influence the Earth¿s climate through their effects on cloud properties. The CLAW hypothesis goes further, and suggests that marine aerosols formed by the sulphur cycle of the ocean and the atmosphere act as a mechanism for regulating the Earth's climate. This effect is produced through the influence of plankton emissions of sulphur compounds on cloud formation. Phytoplankton produces dimethylsulphide (DMS), a highly volatile sulphur compound. Once in the atmosphere, DMS is oxidized and becomes the main source of natural atmospheric sulphates. These sulphates act as condensation nuclei, particles that are essential for the formation of clouds. Those marine particles in the atmosphere play an important role in the Earth's radiation budget. Indirectly they produce a greater amount of cloud droplets. Higher cloud condensation nuclei imply smaller cloud droplets. The efficiency of smaller droplets in reflecting incident solar radiation is greater, resulting in an increase in cloud albedo, producing a cooling effect on the Earth's surface.
To properly study the marine aerosols we need accurate knowledge of the global seawater distribution of the aerosol precursors. Our work focused on the ocean-to-atmosphere emissions of DMS and other biogenic gases that can have an impact on cloud microphysics. During the thesis we updated the monthly global DMS climatology taking advantage of the three-fold increased size and better resolved distribution of the observations available in the DMS database. The emerging patterns found with the previous versions of the database and climatology were explored with the updated version. The statistical relationships between the seasonalities of DMS concentrations and solar radiation doses and chlorophyll a concentrations were here re-examined. Analyses of nine years of satellite data suggested that there is a natural inverse correlation between the spatial cover of low marine clouds and the cloud droplet size, which is related to the presence of small aerosols. This coupled seasonality pushes cloud albedo to contribute higher negative radiative forcing in summer and lower in winter. This relation is disrupted in the marine atmosphere regions heavily impacted by anthropogenic aerosols. Consequently, the potential influence the aerosol precursors have on marine clouds was next analysed over unpolluted and polluted ocean, separately. The 9 years of global satellite data and ocean climatologies were used to derive parameterizations of the production fluxes of secondary aerosols formed by oxidation of DMS and other biogenic organic volatiles. Further, the emission fluxes of biogenic primary organic and sea salt aerosols ejected by wind action on sea surface were also globally studied. Series of weekly estimates of these fluxes were correlated to series of cloud droplet effective radius. The outcome of the statistical analyses indicated that sulphur and organic secondary aerosols might be important in seeding cloud nucleation and droplet activation over mid and high latitude unpolluted oceanic regions. Conversely, primary aerosols (organic and sea salt) showed that, despite contributing to large shares of the marine aerosol mass, they do not seem to be major drivers of the variability of cloud microphysics.
Our results provide partial support for the feasibility of the CLAW hypothesis at the seasonal scale. Despite that DMS has drawn much of the attention on the links between marine biota and climate regulation, the implication of other biogenic precursors on cloud formation provides and suggests a wider scope on the formulation of such hypothesis.Los aerosoles marinos tienen un gran potencial para influir en el clima de la Tierra a través de sus efectos en las propiedades de las nubes. La hipótesis de CLAW va más allá y sugiere que los aerosoles marinos formados por el ciclo del azufre en océanos y atmósfera actúan como un mecanismo para la regulación del clima de la Tierra. Este efecto se produce a través de la influencia de las emisiones de plancton de compuestos de azufre en la formación de nubes. El fitoplancton produce sulfuro de dimetilo (DMS), un compuesto de azufre altamente volátil. Una vez en la atmósfera, el DMS se oxida y se convierte en la principal fuente de sulfatos naturales atmosféricos. Estos sulfatos actúan como núcleos de condensación, partículas esenciales para la formación de nubes. Estas partículas presentes en la atmósfera marina juegan un papel importante en el ciclo radiativo de la Tierra. Indirectamente, producen una mayor cantidad de gotas de las nubes. Mayor número de núcleos de condensación en las nubes implica gotas de nubes más pequeñas. La eficacia de las pequeñas gotas en reflejar la radiación solar incidente es mayor, lo que resulta en un aumento del albedo de las nubes, produciendo un efecto de enfriamiento en la superficie de la Tierra. Para estudiar adecuadamente los aerosoles marinos necesitamos tener un correcto conocimiento de la distribución oceánica global de los precursores de aerosoles. Nuestro trabajo se ha centrado en las emisiones del océano a la atmósfera de DMS y otros gases biogénicos que puede tener un impacto en la microfísica de nubes. Durante la tesis se ha actualizado la climatología mensual global de DMS, aprovechando el aumento en tres veces del número de observaciones y una mejor distribución global de las mismas, en la base de datos de DMS. Los patrones emergentes encontrados con las versiones anteriores de la base de datos y de la climatología se han re-evaluado con la versión actualizada. Las relaciones estadísticas encontradas entre la evolución temporal de las concentraciones de DMS y las dosis de radiación solar y concentraciones de clorofila han sido re-examinadas. Los análisis de nueve años de datos de satélite sugieren que existe una correlación inversa entre la cubierta espacial de nubes marinas bajas y el tamaño de las gotas de nubes, relacionado con la presencia de aerosoles pequeños. Esta estacionalidad acoplada conduce al albedo de las nubes a contribuir a un forzamiento radiativo negativo superior en verano, y más bajo en invierno. Esta relación se interrumpe en las regiones de la atmósfera marina con un alto impacto de los aerosoles antropogénicos. En consecuencia, la posible influencia de los precursores de aerosoles marinos en las nubes se ha analizado en una atmósfera marina limpia y contaminada, por separado. Los 9 años de datos satelitales globales y climatologías oceánicas se han utilizado para derivar las parametrizaciones de los flujos de producción de aerosoles secundarios, formados por la oxidación de DMS, y otros compuestos volátiles orgánicos biogénicos. Además, los flujos de emisiones biogénicas de aerosoles primarios orgánicos y aerosoles de sal marina expulsados por acción del viento sobre la superficie del mar se ha estudiado también a nivel global. Las series semanales de las estimaciones de estos flujos se han correlacionado con las series temporales de los radios de las gotas de nubes. El resultado de los análisis estadísticos ha indicado que el azufre orgánico y otros aerosoles secundarios pueden ser importantes en la nucleación y la activación de sus gotas sobre las regiones oceánicas no contaminadas en latitudes medias y altas. Por el contrario, aerosoles primarios (orgánico y la sal del mar) han mostrado que, a pesar de que contribuyen a una gran proporción de la masa de aerosol marino, no parecen ser los principales motores de la variabilidad de la microfísica de nubes. Nuestros resultados proporcionan un apoyo parcial a la viabilidad de la hipótesis de CLAW a escala estacional. A pesar de que el DMS ha llamado mucho la atención sobre los vínculos entre la biota marina y la regulación del clima, la implicación de otros precursores biogénicos en la formación de nubes ofrece y sugiere un mayor alcance en la formulación de esta hipótesis.
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Mazzola, Homero Jorge. "Incertezas, bifurcações e dilemas na jornada humana." Pontifícia Universidade Católica de São Paulo, 2017. https://tede2.pucsp.br/handle/handle/20589.
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To build a sustainable future is humanity's great mission in a world characterized by deep social inequalities and environmental changes. Saint-Exupéry said: "The future is not a place where we are going, but a place we are creating. The path to it is not found but built and the act of doing so transforms both the creator and his destiny". Man has the competence to begin its construction, however, must transform himself to make it happen. The purpose of this thesis, elaborated in the form of an essay, is to explore possibilities to build this auspicious future, committed to future generations without under valuating the forces that defend the continuity of our way of life. Three fundamental questions ground this work: where do we come from, what are we and where are we going to, that are structured in three human journeys: past, present and future. In the first we find the lessons and learnings of the evolution process, essential for understanding the present and planning the future. The second journey depicts both the human capacity to transform the planet, adapting it to its needs and desires, as the resistance of those who stand against the continuity of the capitalist world system and defy humanity to metamorphose into a meta system rich in possibilities or to sink in a generalized insignificance. On the last journey, the future, it is approached a vision of the complexity of the world and the human psychic nature, which feed discussions about the individual and collective transformations that must occur to generate a desired future. Man has before him uncertainties, bifurcations and dilemmas, which can result in catastrophe or well-being. The social and climatic deterioration, perverse by itself, can also be good, taking the humanity off passivity, leading it to an overall transformation. A plausible path is a new civilizing context grounded in holistic and ecological educational reform, and structured through a truly global society: the World-Society. There is a great challenge ahead. What will happen, however, only the future will show
Construir um futuro sustentável é a grande missão da humanidade em um mundo assinalado por desigualdades sociais enraizadas e mudanças ambientais profundas. Saint-Exupéry disse: “O futuro não é um lugar para onde estamos indo, mas um lugar que estamos criando. O caminho para ele não é encontrado, mas construído e o ato de fazê-lo transforma tanto o realizador quando o destino”. O homem tem competência para iniciar sua construção, mas deverá se transformar para concretizá-lo. Com esta tese, elaborada na forma de um ensaio, exploram-se possibilidades para se construir esse futuro auspicioso, comprometido com as gerações futuras, sem desprezar as forças que defendem a continuidade do nosso modo de vida. Três questões fundamentais a embasam: de onde viemos, quem somos e para onde vamos, que na tese são abordadas na forma de jornadas humanas: passada, presente e futura. Da primeira extraem-se as lições e aprendizados da história evolutiva, imprescindíveis para se compreender o presente e planejar o futuro. A segunda jornada retrata tanto as profundas transformações que o homem produziu no planeta, adequando-o às suas necessidades e desejos, como as reações dos se posicionam contra a continuidade do sistema mundo capitalista e convidam a humanidade a metamorfosear-se em um metassistema rico em possibilidades ou sucumbir no abismo da insignificância generalizada. Na última jornada, a futura, são abordados conhecimentos sobre a complexidade do mundo e sobre a natureza psíquica humana, que alimentam discussões sobre as transformações individuais e coletivas que devem ocorrer para que se possa engendrar um futuro desejado. O homem tem diante de si incertezas, bifurcações e dilemas, que podem conduzi-lo à catástrofe ou ao bem-estar. A deterioração social e climática, perversa por si, pode ser também um bem e tirar a humanidade da passividade, conduzindo a uma mudança abrangente. Um caminho plausível é um novo contexto civilizatório embasado em uma reforma educacional holística e ecológica, e estruturado através de uma sociedade realmente global: uma Sociedade-Mundo. Há um grande desafio à frente. O que acontecerá, entretanto, só o futuro dirá
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Dutreuil, Sébastien. "Gaïa : hypothèse, programme de recherche pour le système terre, ou philosophie de la nature ?" Thesis, Paris 1, 2016. http://www.theses.fr/2016PA01H231.
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Cette thèse est une enquête d'histoire et de philosophie des sciences sur l'hypothèse Gaïa (HG) proposée par Lovelock et Margulis dans les années 1970. L'examen historique de l'élaboration d'HG et de sa très riche réception dans diverses disciplines scientifiques (climatologie, biogéochimie, géochimie, biologie de l'évolution, écologie et sciences de la complexité) et au sein des mouvements environnementalistes nous conduit à montrer qu'une ambiguïté majeure sur le statut d'HG grève la littérature : qu'est-ce qu'HG ? Nous montrons qu'HG a été considérée tantôt comme une hypothèse, tantôt comme une théorie, tantôt comme un programme de recherche, tantôt comme une philosophie de la nature. Chacune de ces lectures est ensuite examinée. Nous proposons une caractérisation épistémologique et historique d'HG montrant qu'HG ne doit pas être interprétée comme une hypothèse devant être confrontée de manière directe aux faits, mais comme une théorie élaborée avec des modèles. Nous clarifions alors le rôle et le statut méthodologique des modèles et théories d'HG ainsi que les concepts et hypothèses fondamentales qui les sous-tendent. La reconnaissance de Gaïa comme un système constitué des vivants et de l'environnement avec lequel ils interagissent a été l'origine de la constitution d'un nouveau programme de recherche: les sciences du système Terre. Nous proposons une histoire et une caractérisation de ce programme, repérons les déplacements philosophiques qu'il a opérés à propos des concepts de vie, d'environnement et de nature puis analysons les liens entre les conceptions que Lovelock a de Gaïa et les prescriptions environnementales qu'il a prononcées au nom de GaïaThe Gaia hypothesis (GH) proposed in the 1970's by Lovelock and Margulis is here analyzed from a history and philosophy of science perspective. The historical analysis of GH's elaboration and rich reception across various disciplines (climatology, biogeochemistry, geochemistry, evolutionary biology, ecology and complexity sciences) and within environmentalist movements leads me to argue that a major ambiguity plagues the relevant literatures: what is GH? I show that GH has been considered as a hypothesis, as a theory, as a research program, or as a philosophy of nature. Each of these interpretations is then analyzed. An epistemological and historical characterisation of GH shows that GH should not be interpreted as a hypothesis which ought to be confronted directly to empirical facts, but as a theory elaborated with models. I elucidate the methodological role and status of GH's models and theories before clarifying the concepts and expliciting the fundamental hypotheses underlying these models and theories. The recognition of Gaia as a system constituted of living organisms and the environment with which they internet led to the constitution of a new research program: the Earth system sciences. I offer a history and a characterisation of this research program, specify the philosophical shifts it brought about concepts such as life, the environment and nature and I analyze the relationships between Lovelock's conceptions of Gaia and the environmental prescriptions he pronounced in the name of Gaia
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Dicks, Henry. "Being and earth : an ecological criticism of late twentieth-century French thought." Thesis, University of Oxford, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.669967.
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Singh, Bhupinder. "The Interplay Between Obesity, Biomechanics and Fitness Within the Reverse Causation Hypothesis." Diss., University of Iowa, 2013. https://ir.uiowa.edu/etd/4912.
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Obesity is a significant public health concern, with implications for the health and well being of millions of people in the United States and world. The purpose of this thesis is to explore the relationship between obesity, segment biomechanics in the form of joint stress and restricted range of motion, and cardiorespiratory fitness. In three studies, anatomical modeling using three dimensional infrared motion capture system was used to calculate joint stresses and range of motion limitations. The results are applied to better understand the impact that obesity has on biomechanics, taking into consideration factors of fitness and fatigue, during walking and common rehabilitation exercises.
The first study compared the biomechanical differences between ten obese and ten normal weight adults while performing squat and lunge exercises and found significant increases in lower limb moments in obese females. Increased moments suggest that obese individuals experience higher biomechanical stress than normal weight individuals and may have less flexibility in selecting movement strategies while performing basic rehabilitation exercises.
The second study examined how walking, a commonly prescribed exercise to combat obesity, may impact an obese individual's joint biomechanics. While the results of this study, comparing joint stress in ten obese and ten normal weight females, did not observe significant differences between the obese and normal weight groups, stronger relationships were present between moments and VO2 max, rather than BMI, suggesting the importance of fitness in context of developing walking programs.
The final study explicitly addressed the relationship between obesity, fitness and biomechanics. Walking and jogging biomechanics was reported in 30 boys and girls, aged 8-11, before and after a fatigue protocol. Hip and knee moments were moderately associated with cardiorespiratory fitness and showed significant increase after cardiorespiratory fatigue. Including measures of adiposity and strength improved the associations between fitness and moments.
This thesis concludes that the relationship between biomechanics and obesity, observed in adults and children, should be understood in the larger framework of the reverse causation hypothesis. The reverse causation hypothesis describes obesity as a positive feedback loop, in which certain factors are related to obesity in a bi-directional manner: both causing, but also amplified by, the presence of excess adipose tissue. While further study is required to clarify these relationships, these associations may have implications for participation in physical activities and long-term effects on the musculoskeletal system, thus illustrating the positive feedback loop of the reverse causation hypothesis.
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Savon, Alexander Able. "The Effect Of Knowledge Gain On Capital Punishment: A Partial Test Of The Marshall Hypothesis." [Tampa, Fla.] : University of South Florida, 2005. http://purl.fcla.edu/fcla/etd/SFE0001181.
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Bauer, Joa. "Industrielle Ökologie theoretische Annäherung an ein Konzept nachhaltiger Produktionsweisen /." [S.l. : s.n.], 2008. http://nbn-resolving.de/urn:nbn:de:bsz:93-opus-36109.
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Jamalabadi, Hamidreza [Verfasser], and Steffen [Akademischer Betreuer] Gais. "Optimizing parameters and algorithms of multivariate pattern classification for hypothesis testing in high-density EEG / Hamidreza Jamalabadi ; Betreuer: Steffen Gais." Tübingen : Universitätsbibliothek Tübingen, 2017. http://d-nb.info/119946936X/34.
Full textBooks on the topic "Gaia hypothesis"
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Canadian Broadcasting Corporation. The leading edge: Gaia hypothesis. Montreal: CBC Transcripts, 1985.
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Kump, Lee R. The earth system. 2nd ed. Upper Saddle River, N.J: Prentice Hall, 2000.
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Camelford Conference on the Implications of the Gaia Thesis (2nd 1988 Camelford, England). Gaia and evolution: Proceedings of the Second Annual Camelford Conference on the Implications of the Gaia Thesis. Camelford, Cornwall [England]: Wadebridge Ecological Centre, 1989.
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Sahtouris, Elisabet. Gaia: The human journey from chaos to cosmos. New York: Pocket Books, 1989.
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Sahtouris, Elisabet. Earthdance: Living systems in evolution. Santa Barbara, CA: Metalog Books, 1996.
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Irwin, Thompson William, Lindisfarne Association, and Lindisfarne Fellows Conference (1981 : San Francisco Zen Center), eds. Gaia, a way of knowing: Political implications of the new biology. Great Barrington, MA: Lindisfarne Press, 1987.
Find full textBook chapters on the topic "Gaia hypothesis"
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Amils, Ricardo. "Gaia Hypothesis." In Encyclopedia of Astrobiology, 1–2. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-27833-4_613-2.
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Amils, Ricardo. "Gaia Hypothesis." In Encyclopedia of Astrobiology, 906. Berlin, Heidelberg: Springer Berlin Heidelberg, 2015. http://dx.doi.org/10.1007/978-3-662-44185-5_613.
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Amils, Ricardo. "Gaia Hypothesis." In Encyclopedia of Astrobiology, 626. Berlin, Heidelberg: Springer Berlin Heidelberg, 2011. http://dx.doi.org/10.1007/978-3-642-11274-4_613.
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Amils, Ricardo. "Gaia Hypothesis." In Encyclopedia of Astrobiology, 1104–5. Berlin, Heidelberg: Springer Berlin Heidelberg, 2023. http://dx.doi.org/10.1007/978-3-662-65093-6_613.
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Visconti, Guido. "The Gaia Hypothesis, Evolution and Ecology." In Climate, Planetary and Evolutionary Sciences, 345–64. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-74713-8_11.
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Margulis, Lynn, and James E. Lovelock. "The Atmosphere as Circulatory System of the Biosphere— The Gaia Hypothesis." In Slanted Truths, 127–43. New York, NY: Springer New York, 1997. http://dx.doi.org/10.1007/978-1-4612-2284-2_10.
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McIntyre Burnham, W., and Georgia A. Cottrell. "The GABA Hypothesis of Kindling." In Advances in Behavioral Biology, 127–39. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4684-5796-4_10.
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Jones, E. Anthony, Cihan Yurdaydin, and Anthony S. Basile. "The GABA Hypothesis — State of the Art." In Advances in Experimental Medicine and Biology, 89–101. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4615-1989-8_9.
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Podbregar, Nadja. "Organismus Erde? Von der Gaia-Hypothese zum System Erde." In Im Fokus: Geowissen, 153–60. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-34791-7_12.
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Ferenci, Peter. "The GABA Hypothesis of the Pathogenesis of Hepatic Encephalopathy: Current Status." In Assessment and Management of Hepatobiliary Disease, 431–35. Berlin, Heidelberg: Springer Berlin Heidelberg, 1987. http://dx.doi.org/10.1007/978-3-642-72631-6_56.
Full textConference papers on the topic "Gaia hypothesis"
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Tsamis, Alexandros, Ana Cecilia Toledano, and Mohammed Alnaggar. "Towards Functionally Graded Bio-Composites in Additive Manufacturing." In 108th Annual Meeting Proceedings. ACSA Press, 2020. http://dx.doi.org/10.35483/acsa.am.108.9.
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Anthropogenic greenhouse gas emissions warming up the Earth’s atmosphere and triggering a climatic shift around the world evidence how the construction industry must provide a resilient built environment for an increasingly growing population, while at the same time reduce the use of cement and the demand for energy use from heating and cooling in an intensely urbanized world. Construction using Additive Manufacturing (AM) has gained traction in recent years, promising benefits such as: reduction in waste, building time, and need for formwork; customization and fabrication of complex geometries at no extra cost; and the reduction of human labor and on-site hazards. While most implementations of AM use cement as a primary material, development of alternative technologies that use earth-abundant, low-carbon renewable materials can be seen in projects such as Gaia by WASP, as well as efforts from the Institute for Advanced Architecture of Catalonia (IAAC). As a research framework, this project extends the efforts of building with renewable materials by developing a Functionally Graded Material (FGM) 3d Printing technology to create a bio-composite wall using lime, clay and hemp bast fiber. Unlike traditional, singular material deploying AM technologies, FGMs are a type of composite that use different materials according to where they are needed, with gradient transitioning between the materials to achieve non-discrete interphases. We work under the hypothesis that FGMs can achieve better strength-to-weight ratios than regular ceramics, and at the same time allow, through the 3d printing process, for an expression of the functional requirements of material change through form. While used in fields other than architecture, FGMs in AM have yet to be implemented in building construction.
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Berry, John. "Culture + Behaviour + Comparison = Cross-Cultural Psychology." In International Association of Cross Cultural Psychology Congress. International Association for Cross-Cultural Psychology, 2016. http://dx.doi.org/10.4087/hvih1135.
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For many years I have advocated the view that cross-cultural psychology should have the following characteristics: it begins with an ethnographic search to select those settings that may provide the cultural and ecological contexts that are theoretically-relevant to the development of the particular behaviour of interest; this is followed by advancing hypotheses that link the context to the behaviour; then fieldwork is undertaken to further examine these cultural attributes, and to carry out the assessment of the behaviour of individuals. These activities are carried out across contexts for three reasons: (i) in order to gain sufficient variation in the cultural and behavioural information to allow the examination of their co-variation (ie. to assess the hypothesis); (ii) to search for universals in the structure of behaviours; and (iii) to allow the possible discovery of universals in culture- behaviour relationships. In my view, cross-cultural psychology is cultural first, then psychological, and then comparative.
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Blazek, Katerina, Jennifer Erhart, Jessica Asay, and Thomas Andriacchi. "Relationship of Knee Articular Cartilage Thickness to Body Mass Index and Gait Mechanics." In ASME 2010 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2010. http://dx.doi.org/10.1115/sbc2010-19409.
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In longitudinal studies, obesity has been shown to be a major risk factor for knee osteoarthritis (OA) (Felson, 1988), but the cause of this increased prevalence is not yet clear. A common hypothesis is that obesity increases joint loads due to increased body mass, causing the articular cartilage to experience higher load and degenerate more quickly (Griffin, 2005). However, it has been shown that in healthy, normal-weight subjects, knee cartilage thickness increases in proportion to the loads applied during ambulation (Andriacchi, 2004). It is not known whether this same relationship also holds true for obese people who do not have OA. Because it is difficult to measure joint loads directly in vivo, the external adduction moment can be used as a surrogate measure of the relative load distribution between the medial and lateral compartments of the knee (Andriacchi 2004). If cartilage responds positively to load, a higher adduction moment will be correlated with thicker cartilage on the medial side and thinner cartilage in the lateral compartment. Similarly, average cartilage thickness should be proportional to body mass index. Therefore the purpose of this study was to examine the following hypotheses in a group of healthy-weight, overweight, and obese individuals: 1. Average cartilage thickness in both compartments is proportional to body mass index (BMI). 2. Average cartilage thickness in the lateral compartment is inversely proportional to the knee adduction moment. 3. Average cartilage thickness in the medial compartment is proportional to the knee adduction moment. 4. The ratio of medial to lateral cartilage thickness is proportional to the adduction moment.
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Mamedov, Farrukh, Viktor Artemyev, and Vitaly Kargin. "Using Statistical Methods to Assess the Accuracy of Production Process Control Systems." In 2nd International Scientific-Practical Conference "Machine Building and Energy: New Concepts and Technologies". Switzerland: Trans Tech Publications Ltd, 2024. http://dx.doi.org/10.4028/p-udgl54.
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In today's highly competitive industrial landscape, maintaining the accuracy of production processes is paramount. This article explores the critical role of statistical methods in evaluating and enhancing the precision of production process control systems. Statistical techniques offer a data-driven approach to monitor and optimize production processes, enabling early issue detection, resource optimization, and continuous improvement. By assessing the accuracy of these control systems, organizations can not only deliver higher-quality products but also gain a competitive edge, reduce risks, and enhance customer satisfaction. While production process control systems are critical for maintaining product quality and efficiency, several challenges persist in their implementation. Variability in raw materials, equipment wears and tear, and external factors can all contribute to deviations from desired standards. These challenges necessitate a robust approach to control and monitoring, which is where statistical methods play a pivotal role. One of the fundamental statistical tools used in assessing the accuracy of production process control systems is hypothesis testing. By formulating hypotheses regarding process parameters and conducting statistical tests, manufacturers can determine whether their processes are operating within acceptable limits. This article underscores the significance of integrating statistical methods into modern manufacturing practices and highlights the benefits they bring to industries seeking sustainable growth.
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Hurwitz, D. E., K. C. Foucher, T. P. Andriacchi, A. G. Rosenberg, and J. O. Galante. "Similarities Between Gait Adaptations in Preoperative and Postoperative Total Hip Replacement Patients." In ASME 1997 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1997. http://dx.doi.org/10.1115/imece1997-0334.
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Abstract Gait adaptations among postoperative total hip replacement (THR) patients may be a response to the prosthesis and changes in the reconstructed joint mechanics or may be a learned response from an adaptation that was present preoperatively. Similarities have been reported between gait adaptations in preoperative and postoperative patients for THRs (1), but this was demonstrated in cross-sectional data and not longitudinal data. These gait adaptations may have implications on hip joint loading, rehabilitation protocols and can result in additional compensations at other joints. This longitudinal study tested the hypothesis that gait adaptations present preoperatively persist postoperatively.
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Higo, Eishiro, and Mahesh D. Pandey. "Value of Information and Hypothesis Testing Approaches for Sample Size Determination in Engineering Component Inspection: A Comparison." In ASME 2016 Pressure Vessels and Piping Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/pvp2016-63932.
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A sample size determination method is developed for a two-action problem that represents a component maintenance scenario requiring current state estimation. For safety and generation efficiency, each component of a nuclear power plant must be regularly inspected. In terms of safety, the larger the sample size inspected, the less the uncertainty about current and future states of the components; however, such inspections are expensive. Thus, sample size determination becomes an important problem. A key idea for solving this problem is the Value of Information (VoI) and its derivation: the Expected Net Gain of Sampling (ENGS). The ENGS is a function of sample size and represents by how much a decision maker benefits from the observed data. By maximizing the ENGS, the optimal sample size is determined in terms of cost-benefit analysis.
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Borrelli, James, and Henry W. Haslach. "Rationale for a Modified Crutch Use Methodology for Individuals With Weak or Paralyzed Hip Abductor Muscles." In ASME 2013 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/detc2013-12642.
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Individuals with weak or paralyzed hip abductors may make use of two methods to reduce pathological gait kinematics as a result of their disability; reducing the need for the hip abductors or developing an equivalent torque on the body. Compensatory motions such as torso tilting or hip hiking “balance” the body reducing the need for the torque that would be developed by the hip abductors. A contralateral crutch develops a body torque that is equivalent to that developed by the hip abductors. Individuals with weak or paralyzed hip abductors intuitively adopt a wide crutch stance, contrary to the prescribed method where the crutches are vertical in the frontal plane. Using a wide stance angle in the frontal plane is hypothesized to improve gait with weak or paralyzed hip abductors more so than when using crutches in the traditional manner. Crutches develop a torque on the body that is equivalent to what would be developed by the hip abductors while standing still. A wide stance angle increases the moment arm that the crutch force acts through while standing still, increasing the torque developed, potentially increasing the positive effect of the crutch which may reduce the need for compensatory motions. However, a similar effect has not been characterized during gait. The hypothesis is that a wide crutch stance angle improves a gait with paralyzed hip abductors more so than a crutch used vertically in the frontal plane. The assumption is that this is accomplished by decreasing energy expenditure and/or reducing the need for compensatory motions more so than a crutch used vertically in the frontal plane. A three-dimensional dynamic model is used to test the hypothesis. The model predicts that excessive pelvis depression and decreased pelvic rotation result when the hip abductors are paralyzed. Compensatory motions, hip hiking and torso tilting, and crutch use are shown to decrease the prevalence of pathological kinematics. Crutch use with a wide stance angle improves gait kinematics more than a vertical crutch with the same body weight supported on it. This study provides evidence that the need for compensatory motions and the prevalence of pathological gait kinematics may be reduced when using a wide crutch stance angle compared to a vertical crutch stance angle.
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Hurwitz, D. E., C. H. Hulet, R. D. Sumner, T. P. Andriacchi, J. O. Galante, and A. G. Rosenberg. "The Influence of Loading During Gait on Bone Loss in Preoperative Patients for Total Hip Replacement." In ASME 1996 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 1996. http://dx.doi.org/10.1115/imece1996-1327.
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Abstract Extensive periprosthetic bone loss in total hip replacement (THR) has been attributed primarily to stress shielding. However, it is well known that decreased loading can result in bone loss (1). There is also evidence that subjects with a THR walk in an asymmetric manner that reduces the loads on the affected side (2). Decreased loading during daily activities may contribute to periprosthetic bone loss in addition to that due to stress-shielding. This study tested the hypothesis that asymmetries during gait were related to asymmetries in femoral bone mineral density (BMD).
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Habibi, S. R., J. Roach, and G. Luecke. "Inner-Loop Feedback for Deadband Compensation in Electromechanical Flight Surface Actuation Systems." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-81092.
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This manuscript pertains to the application of an inner-loop control strategy to electro-mechanical flight surface actuation systems. Modular Electro-Mechanical Actuators (EMA) are increasingly used in-lieu of centralized hydraulics for the control of flight surfaces in the aerospace sector. The presence of what is termed as a dead zone in these actuators significantly affects the maneuverability, stability, and the flight profiles of aircrafts that use this actuation concept. The hypothesis of our research is that flight surface actuation systems may be desensitized to the effects of dead zone by using a control strategy with multiple inner-loops. The proposed strategy involves: high-gain inner-loop velocity control of the driving motor; and inner-loop compensation for the differential velocity between the motor versus the aileron. Our results indicate that this strategy is very effective and that it can considerably improve the system’s performance. The above hypothesis is confirmed by theoretical and simulated analysis using the model of an EMA flight surface actuator.
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Garafolo, Nicholas G., and Christopher C. Daniels. "Geometrical Consideration of Permeation in Elastomers." In ASME 2013 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/fedsm2013-16059.
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Elastomer seals for space applications are integral for the success of manned space flight. These seals inhibit the loss of habitable cabin air to the vacuum of Space. The loss of breathable atmosphere due to leaks of a seal must be replaced through the use of a costly make-up air system. A cost-effective sealing solution for long-duration manned space flight is thereby enabled by seal leak mitigation, while maintaining acceptable behavior in other requirements (e.g., closure force, reusability). Thus, there is a need for optimization from a multitude of geometric possibilities. To facilitate the selection of space seals mechanisms, designers and researchers have relied heavily on engineering judgment and intuition in the design phase of equipment. The main geometric hypothesis utilized in past design is that the leak rate depends on two aspects: (1) the permeation path length, and (2) the wetted gas-elastomer contact area. The research detailed herein highlights the necessity for computational prediction methods in the preliminary phase of space seal design. To this end, a series of computational analyses were performed utilizing a compressible permeation approach to elastomeric space seals. Utilizing a simple rectangular domain, the hypotheses were confirmed and are reflected in an analysis of the model equations, however, for one-dimensional flow. Unique to this analysis, additional domains were studied incorporating a periodic perturbation in the sidewalls. The analysis simulated the leak rate of each seal design domain, as manufactured from silicone elastomer S0383-70. Foremost, results highlight the significance of the leak rate prediction methodology, as mere engineering intuition does not always lead to true design optimization. A study in the boundary conditions is also presented, whereas the elastomeric nature of space seal materials can be utilized for a strategic gain in leak rate performance. As an additional benefit, the analysis proved its merit as a cost reduction technique. Whereas by undergoing design iterations in a virtual environment, the cost associated with manufacturing faulty designs are eliminated.
Reports on the topic "Gaia hypothesis"
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Montiel, Peter J., and Eduardo Fernández-Arias. Reform and Growth in Latin America: all Pain, no Gain? Inter-American Development Bank, June 1997. http://dx.doi.org/10.18235/0011599.
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This paper addresses the adequacy of post-reform growth in Latin America in the 1990s on the basis of international comparison and other relevant standards. It analytically explores and empirically tests a number of hypotheses to explain the perceived dissatisfaction with growth performance.
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O'Rourke, Kevin, and Jeffrey Williamson. Did Vasco da Gama Matter for European Markets? Testing Frederick Lane's Hypotheses Fifty Years Later. Cambridge, MA: National Bureau of Economic Research, December 2005. http://dx.doi.org/10.3386/w11884.
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Canto, Patricia, ed. Learning Modes, Types of Innovation and Economic Performance. Universidad de Deusto, 2012. http://dx.doi.org/10.18543/xebj1954.
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This contribution focuses on a current heated debate on learning modes employed by the firms, and their impact on innovation and economic output. The interactive approach developed by the Scandinavian school on innovation systems characterized two key learning modes as „science and technology-based innovation? (STI) and „learning-by-doing, by-using and by-interacting-based innovation (DUI). This work analyzes first the separate and combined impact of such modes of learning and innovation on two types of innovation output: product and process. In this operation, this work produces interesting and challenging results. Moreover, this paper offers the original hypothesis that these learning modes have a differentiated impact on product and process innovation. Simultaneously, this contribution adds a further analytical element, which is the explicit connection to the capacity of firms to transform innovation output (product and process) in economic performance. A two-stage mode is formulated and applied in the context of an extensive database of Spanish manufacturing and service firms (PITEC). This allows implementing an original time-series analysis that leads to obtaining insightful results that question former analyses and might heat further the debate on the most effective learning and innovation modes applied by firms as a means to gain competitiveness in open markets.
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Paterson, Andrew H., Yehoshua Saranga, and Dan Yakir. Improving Productivity of Cotton (Gossypsum spp.) in Arid Region Agriculture: An Integrated Physiological/Genetic Approach. United States Department of Agriculture, December 1999. http://dx.doi.org/10.32747/1999.7573066.bard.
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Objectives: We seek to establish the basis for improving cotton productivity under arid conditions, by studying the water use efficiency - evaporative cooling interrelationship. Specifically, we will test the hypothesis that cotton productivity under arid conditions can be improved by combining high seasonal WUE with efficient evaporative cooling, evaluate whether high WUE and/or evaporative cooling are based on specific physiological factors such as diurnal flexibility in stomatal conductance, stomatal density, photosynthetic capacity, chlorophyll fluorescence, and plant water status. Genes influencing both WUE and evaporative cooling, as well as other parameters such as economic products (lint yield, quality, harvest index) of cotton will also be mapped, in order to evaluate influences of water relations on these parameters. Approach: Carbon isotope ratio will be used to evaluate WUE, accompanied by additional parameters to elucidate the relationship between WUE, evaporative cooling, and cotton productivity. A detailed RFLP map will be used to determine the number, location, and phenotypic effects of genes underlying genetic variation in WUE between cultivated cottons, as well as test associations of these genes with traits of economic importance such as harvest index, lint yield, and lint quality. Major Conclusions: Productivity and quality of cotton grown under well-watered versus water-limited conditions was shown to be partly accounted for by different quantitative trait loci (QTLs). Among a suite of physiological traits often found to differ between genotypes adapted to arid versus well-watered conditions, genetic mapping implicated only reduced plant osmotic potential in improved cotton productivity under arid conditions. Our findings clearly implicate OP as a major component of cotton adaptation to arid conditions. However, testing of further physiological hypotheses is clearly needed to account for additional QTL alleles conferring higher seed-cotton yield under arid conditions, such as three of the five we found. Near-isogenic lines being made for QTLs discovered herein will offer a powerful new tool useful toward identification of the underlying gene(s) by using fine-scale mapping approaches (Paterson et al 1990). Implications: Adaptation to both arid and favorable conditions can be combined into the same genotype. We have identified diagnostic DNA markers that are being applied to creation of such desirable genotypes. Simultaneous improvement of productivity (and/or quality) for both arid and irrigated conditions will require more extensive field testing and the manipulation of larger numbers of genes, reducing the expected rate of genetic gain These difficulties may be at least partly ameliorated by efficiencies gained through identification and use of diagnostic DNA markers. Genomic tools and approaches may expedite adaptation of crops to arid cultivation, help to test roles of additional physiological factors, and guide the isolation of the underlying genes that protect crop performance under arid conditions.
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Wisniewski, Michael E., Samir Droby, John L. Norelli, Noa Sela, and Elena Levin. Genetic and transcriptomic analysis of postharvest decay resistance in Malus sieversii and the characterization of pathogenicity effectors in Penicillium expansum. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7600013.bard.
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Blue mold of apple caused by Penicilliumexpansumis a major postharvest disease. Selection for postharvest disease resistance in breeding programs has been ignored in favor of fruit quality traits such as size, color, taste, etc. The identification of postharvest disease resistance as a heritable trait would represent a significant accomplishment and has not been attempted in apple. Furthermore, insight into the biology of the pathogenicity of P. expansumin apple could provide new approaches to postharvest decay management. Hypothesis: Postharvest resistance of apple to P. expansumcan be mapped to specific genetic loci and significant quantitative-trait-loci (QTLs) can be identified that account for a major portion of the population variance. Susceptibility of apple fruit to P. expansumis dependent on the ability of the pathogen to produce LysM effectors that actively suppress primary and/or secondary resistance mechanisms in the fruit. Objectives: 1) Identify QTL(s) and molecular markers for blue mold resistance in GMAL4593 mapping population (‘Royal Gala’ X MalussieversiiPI613981), 2) Characterize the transcriptome of the host and pathogen (P. expansum) during the infection process 3) Determine the function of LysM genes in pathogenicity of P. expansum. Methods: A phenotypic evaluation of blue mold resistance in the GMAL4593 mapping population, conducted in several different years, will be used for QTL analysis (using MapQTL 6.0) to identify loci associated with blue mold resistance. Molecular markers will be developed for the resistance loci. Transcriptomic analysis by RNA-seq will be used to conduct a time course study of gene expression in resistant and susceptible apple GMAL4593 genotypes in response to P. expansum, as well as fungal responses to both genotypes. Candidate resistance genes identified in the transcriptomic study and or bioinformatic analysis will be positioned in the ‘Golden Delicious’ genome to identify markers that co-locate with the identified QTL(s). A functional analysis of LysM genes on pathogenicity will be conducted by eliminating or reducing the expression of individual effectors by heterologous recombination and silencing technologies. LysMeffector genes will also be expressed in a yeast expression system to study protein function. Expected Results: Identification of postharvest disease resistance QTLs and tightly-linked genetic markers. Increased knowledge of the role of effectors in blue mold pathogenic
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Weinberg, Zwi G., Richard E. Muck, Nathan Gollop, Gilad Ashbell, Paul J. Weimer, and Limin Kung, Jr. effect of lactic acid bacteria silage inoculants on the ruminal ecosystem, fiber digestibility and animal performance. United States Department of Agriculture, September 2003. http://dx.doi.org/10.32747/2003.7587222.bard.
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The overall objective of the whole research was to elucidate the mechanisms by which LAB silage inoculants enhance ruminant performance. The results generated will permit the development of better silage inoculants that maximize both silage preservation and animal performance. For this one-year BARD feasibility study, the objectives were to: 1. determine whether lactic acid bacteria (LAB) used in inoculants for silage can survive in rumen fluid (RF) 2.select the inoculants that survived best, and 3. test whether LAB silage inoculants produce bacteriocins-like substances. The most promising strains will be used in the next steps of the research. Silage inoculants containing LAB are used in order to improve forage preservation efficiency. In addition, silage inoculants enhance animal performance in many cases. This includes improvements in feed intake, liveweight gain and milk production in 25-40% of studies reviewed. The cause for the improvement in animal performance is not clear but appears to be other than direct effect of LAB inoculants on silage fermentation. Results from various studies suggest a possible probiotic effect. Our hypothesis is that specific LAB strains interact with rumen microorganisms which results in enhanced rumen functionality and animal performance. The first step of the research is to determine whether LAB of silage inoculants survive in RF. Silage inoculants (12 in the U.S. and 10 in Israel) were added to clarified and strained RF. Inoculation rate was 10 ⁶ (clarified RF), 10⁷ (strained RF) (in the U.S.) and 10⁷, 10⁸ CFU ml⁻¹ in Israel (strained RF). The inoculated RF was incubated for 72 and 96 h at 39°C, with and without 5 g 1⁻¹ glucose. Changes in pH, LAB numbers and fermentation products were monitored throughout the incubation period. The results indicated that LAB silage inoculants can survive in RF. The inoculants with the highest counts after 72 h incubation in rumen fluid were Lactobacillus plantarum MTD1 and a L. plantarum/P. cerevisiae mixture (USA) and Enterococcus faecium strains and Lactobacillus buchneri (Israel). Incubation of rumen fluid with silage LAB inoculants resulted in higher pH values in most cases as compared with that of un-inoculated controls. The magnitude of the effect varied among inoculants and typically was enhanced with the inoculants that survived best. This might suggest the mode of action of LAB silage inoculants in the rumen as higher pH enhances fibrolytic microorganisms in the rumen. Volatile fatty acid (VFA) concentrations in the inoculated RF tended to be lower than in the control RF after incubation. However, L. plalltarull1 MTDI resulted in the highest concentrations of VFA in the RF relative to other inoculants. The implication of this result is not as yet clear. In previous research by others, feeding silages which were inoculated with this strain consistently enhanced animal performance. These finding were recently published in Weinberg et.al.. (2003), J. of Applied Microbiology 94:1066-1071 and in Weinberg et al.. (2003), Applied Biochemistry and Biotechnology (accepted). In addition, some strains in our studies have shown bacteriocins like activity. These included Pediococcus pentosaceus, Enterococcus faecium and Lactobacillus plantarum Mill 1. These results will enable us to continue the research with the LAB strains that survived best in the rumen fluid and have the highest potential to affect the rumen environment.
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Dudley, Lynn M., Uri Shani, and Moshe Shenker. Modeling Plant Response to Deficit Irrigation with Saline Water: Separating the Effects of Water and Salt Stress in the Root Uptake Function. United States Department of Agriculture, March 2003. http://dx.doi.org/10.32747/2003.7586468.bard.
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Standard salinity management theory, derived from blending thermodynamic and semi- empirical considerations leads to an erroneous perception regarding compensative interaction among salinity stress factors. The current approach treats matric and osmotic components of soil water potential separately and then combines their effects to compute overall response. With deficit water a severe yield decrease is expected under high salinity, yet little or no reduction is predicted for excess irrigation, irrespective of salinity level. Similarly, considerations of competition between chloride and nitrate ions have lead to compensation hypothesis and to application of excess nitrate under saline conditions. The premise of compensative interaction of growth factors behind present practices (that an increase in water application alleviates salinity stress) may result in collateral environmental damage. Over-irrigation resulting in salinization and elevated ground water threatens productivity on a global scale. Other repercussions include excessive application of nitrate to compensate for salinity, unwillingness to practice deficit irrigation with saline water, and under-utilization of marginal water. The objectives for the project were as follows: 1) To develop a database for model parameterization and validation by studying yield and transpiration response to water availability, excessive salinity and salt composition. 2) To modify the root sink terms of an existing mechanism-based model(s) of water flow, transpiration, crop yield, salt transport, and salt chemistry. 3) To develop conceptual and quantitative models of ion uptake that considers the soil solution concentration and composition. 4) To develop a conceptual and quantitative models of effects of NaCl and boron accumulation on yield and transpiration. 5) To add a user interface to the water flow, transpiration, crop yield, salt transport, chemistry model to make it easy for others to use. We conducted experiments in field plots and lysimeters to study biomass production and transpiration of com (Zeamays cv. Jubilee), melon (Cucumismelo subsp. melo cv. Galia), tomato (Lycopersiconesculentum Mill. cv. 5656), onion (Alliumcepa L. cv. HA 944), and date palms (Phoenix Dactylifera L. cv. Medjool) under salinity combined with water or with nitrate (growth promoters) or with boron (growth inhibitor). All factors ranged from levels not limiting to plant function to severe inhibition. For cases of combined salinity with water stress, or excess boron, we observed neither additive nor compensative effects on plant yield and transpiration. In fact, yield and transpiration at each combination of the various factors were primarily controlled by one of them, the most limiting factor to plant activity. We proposed a crop production model of the form Yr = min{gi(xi), where Yr = Yi ym-1 is relative yield,Ym is the maximum yield obtained in each experiment, Xi is an environmental factor, gi is a piecewise-linear response function, Yi is yield of a particular treatment. We selected a piecewise-linear approach because it highlights the irrigation level where the response to one factor ceases and a second factor begins. The production functions generate response "envelopes" containing possible yields with diagonal lines represent response to Xi alone and the lines parallel to the X-axis represent response to salinity alone. A multiplicative model was also derived approximating the limiting behaviour for incorporation in a hydrochemical model. The multiplicative model was selected because the response function was required to be continuous. The hydrochemical model was a better predictor of field-measured water content and salt profiles than models based on an additive and compensative model of crop response to salinity and water stress.
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Weller, Joel I., Derek M. Bickhart, Micha Ron, Eyal Seroussi, George Liu, and George R. Wiggans. Determination of actual polymorphisms responsible for economic trait variation in dairy cattle. United States Department of Agriculture, January 2015. http://dx.doi.org/10.32747/2015.7600017.bard.
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The project’s general objectives were to determine specific polymorphisms at the DNA level responsible for observed quantitative trait loci (QTLs) and to estimate their effects, frequencies, and selection potential in the Holstein dairy cattle breed. The specific objectives were to (1) localize the causative polymorphisms to small chromosomal segments based on analysis of 52 U.S. Holstein bulls each with at least 100 sons with high-reliability genetic evaluations using the a posteriori granddaughter design; (2) sequence the complete genomes of at least 40 of those bulls to 20 coverage; (3) determine causative polymorphisms based on concordance between the bulls’ genotypes for specific polymorphisms and their status for a QTL; (4) validate putative quantitative trait variants by genotyping a sample of Israeli Holstein cows; and (5) perform gene expression analysis using statistical methodologies, including determination of signatures of selection, based on somatic cells of cows that are homozygous for contrasting quantitative trait variants; and (6) analyze genes with putative quantitative trait variants using data mining techniques. Current methods for genomic evaluation are based on population-wide linkage disequilibrium between markers and actual alleles that affect traits of interest. Those methods have approximately doubled the rate of genetic gain for most traits in the U.S. Holstein population. With determination of causative polymorphisms, increasing the accuracy of genomic evaluations should be possible by including those genotypes as fixed effects in the analysis models. Determination of causative polymorphisms should also yield useful information on gene function and genetic architecture of complex traits. Concordance between QTL genotype as determined by the a posteriori granddaughter design and marker genotype was determined for 30 trait-by-chromosomal segment effects that are segregating in the U.S. Holstein population; a probability of <10²⁰ was used to accept the null hypothesis that no segregating gene within the chromosomal segment was affecting the trait. Genotypes for 83 grandsires and 17,217 sons were determined by either complete sequence or imputation for 3,148,506 polymorphisms across the entire genome. Variant sites were identified from previous studies (such as the 1000 Bull Genomes Project) and from DNA sequencing of bulls unique to this project, which is one of the largest marker variant surveys conducted for the Holstein breed of cattle. Effects for stature on chromosome 11, daughter pregnancy rate on chromosome 18, and protein percentage on chromosome 20 met 3 criteria: (1) complete or nearly complete concordance, (2) nominal significance of the polymorphism effect after correction for all other polymorphisms, and (3) marker coefficient of determination >40% of total multiple-regression coefficient of determination for the 30 polymorphisms with highest concordance. The missense polymorphism Phe279Tyr in GHR at 31,909,478 base pairs on chromosome 20 was confirmed as the causative mutation for fat and protein concentration. For effect on fat percentage, 12 additional missensepolymorphisms on chromosome 14 were found that had nearly complete concordance with the suggested causative polymorphism (missense mutation Ala232Glu in DGAT1). The markers used in routine U.S. genomic evaluations were increased from 60,000 to 80,000 by adding markers for known QTLs and markers detected in BARD and other research projects. Objectives 1 and 2 were completely accomplished, and objective 3 was partially accomplished. Because no new clear-cut causative polymorphisms were discovered, objectives 4 through 6 were not completed.
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Meir, Shimon, Michael S. Reid, Cai-Zhong Jiang, Amnon Lers, and Sonia Philosoph-Hadas. Molecular Studies of Postharvest Leaf and Flower Senescence. United States Department of Agriculture, January 2011. http://dx.doi.org/10.32747/2011.7592657.bard.
Full textAbstract:
Original objectives: To understand the regulation of abscission by exploring the nature of changes of auxin-related gene expression in tomato (Lycopersicon esculatumMill) abscission zones (AZs) following organ removal, and by analyzing the function of these genes. Our specific goals were: 1) To complete the microarray analyses in tomato flower and leaf AZs, for identifying genes whose expression changes early in response to auxin depletion; 2) To examine, using virus-induced gene silencing (VIGS), the effect of silencing target genes on ethylene sensitivity and abscission competence of the leaf and flower AZs; 3) To isolate and characterize promoters from AZ-specific genes to be used in functional analysis; 4) To generate stable transgenic tomato plants with selected genes silenced with RNAi, under the control of an AZ-specific promoter, for further characterization of their abscission phenotypes. Background: Abscission, the separation of organs from the parent plant, results in postharvest quality loss in many ornamentals and other fresh produce. The process is initiated by changes in the auxin gradient across the AZ, and is triggered by ethylene. Although changes in gene expression have been correlated with the ethylene-mediated execution of abscission, there is almost no information on the initiation of the abscission process, as the AZ becomes sensitized to ethylene. The present project was focused on elucidating these early molecular regulatory events, in order to gain a better control of the abscission process for agricultural manipulations. Major conclusions, solutions, achievements: Microarray analyses, using the Affymetrix Tomato GeneChip®, revealed changes in expression, occurring early in abscission, of many genes with possible regulatory functions. These included a range of auxin- and ethylene-related transcription factors (TFs), other TFs that are transiently induced just after flower removal, and a set of novel AZ-specific genes. We also identified four different defense-related genes, including: Cysteine-type endopeptidase, α- DOX1, WIN2, and SDF2, that are newly-associated with the late stage of the abscission process. This supports the activation of different defense responses and strategies at the late abscission stages, which may enable efficient protection of the exposed tissue toward different environmental stresses. To facilitate functional studies we implemented an efficient VIGS system in tomato, and isolated two abscission-specific promoters (pTAPG1 and pTAPG4) for gene silencing in stable transformation. Using the VIGS system we could demonstrate the importance of TAPGs in abscission of tomato leaf petioles, and evaluated the importance of more than 45 genes in abscission. Among them we identified few critical genes involved in leaf and flower abscission. These included: PTRP-F1, PRP, TKN4, KNOTTED-like homeobox TF, KD1, and KNOX-like homeodomain protein genes, the silencing of which caused a striking retardation of pedicel abscission, and ERF1, ERF4, Clavata-like3 protein, Sucrose transporter protein, and IAA10 genes, the silencing of which delayed petiole abscission. The importance of PRPand KD1 genes in abscission was confirmed also by antisense–silencing using pTAPG4. Experiments testing the effects of RNAi silencing of few other genes are still in progress, The analysis of the microarray results of flower and leaf AZs allowed us to establish a clear sequence of events occurring during acquisition of tissue sensitivity to ethylene, and to confirm our hypothesis that acquisition of ethylene sensitivity in the AZ is associated with altered expression of auxin-regulated genes in both AZs. Implication, both scientific and agricultural: Our studies had provided new insights into the regulation of the abscission process, and shaded light on the molecular mechanisms that drive the acquisition of abscission competence in the AZ. We pointed out some critical genes involved in regulation of abscission, and further expanded our knowledge of auxin-ethylene cross talk during the abscission process. This permits the development of novel techniques for manipulating abscission, and thereby improving the postharvest performance of ornamentals and other crops.
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Yahav, Shlomo, John Brake, and Orna Halevy. Pre-natal Epigenetic Adaptation to Improve Thermotolerance Acquisition and Performance of Fast-growing Meat-type Chickens. United States Department of Agriculture, September 2009. http://dx.doi.org/10.32747/2009.7592120.bard.
Full textAbstract:
: The necessity to improve broiler thermotolerance and performance led to the following hypothesis: (a) thethermoregulatory-response threshold for heat production can be altered by thermal manipulation (TM) during incubation so as to improve the acquisition of thermotolerance in the post-hatch broiler;and (b) TM during embryogenesis will improve myoblast proliferation during the embryonic and post-hatch periods with subsequent enhanced muscle growth and meat production. The original objectives of this study were as follow: 1. to assess the timing, temperature, duration, and turning frequency required for optimal TM during embryogenesis; 2. to evaluate the effect of TM during embryogenesis on thermoregulation (heat production and heat dissipation) during four phases: (1) embryogenesis, (2) at hatch, (3) during growth, and (4) during heat challenge near marketing age; 3. to investigate the stimulatory effect of thermotolerance on hormones that regulate thermogenesis and stress (T₄, T₃, corticosterone, glucagon); 4. to determine the effect of TM on performance (BW gain, feed intake, feed efficiency, carcass yield, breast muscle yield) of broiler chickens; and 5. to study the effect of TM during embryogenesis on skeletal muscle growth, including myoblast proliferation and fiber development, in the embryo and post-hatch chicks.This study has achieved all the original objectives. Only the plasma glucagon concentration (objective 3) was not measured as a result of technical obstacles. Background to the topic: Rapid growth rate has presented broiler chickens with seriousdifficulties when called upon to efficiently thermoregulate in hot environmental conditions. Being homeotherms, birds are able to maintain their body temperature (Tb) within a narrow range. An increase in Tb above the regulated range, as a result of exposure to environmental conditions and/or excessive metabolic heat production that often characterize broiler chickens, may lead to a potentially lethal cascade of irreversible thermoregulatory events. Exposure to temperature fluctuations during the perinatal period has been shown to lead to epigenetic temperature adaptation. The mechanism for this adaptation was based on the assumption that environmental factors, especially ambient temperature, have a strong influence on the determination of the “set-point” for physiological control systems during “critical developmental phases.” In order to sustain or even improve broiler performance, TM during the period of embryogenesis when satellite cell population normally expand should increase absolute pectoralis muscle weight in broilers post-hatch. Major conclusions: Intermittent TM (39.5°C for 12 h/day) during embryogenesis when the thyroid and adrenal axis was developing and maturing (E7 to E16 inclusive) had a long lasting thermoregulatory effect that improved thermotolerance of broiler chickens exposed to acute thermal stress at market age by lowering their functional Tb set point, thus lowering metabolic rate at hatch, improving sensible heat loss, and significantly decreasing the level of stress. Increased machine ventilation rate was required during TM so as to supply the oxygen required for the periods of increased embryonic development. Enhancing embryonic development was found to be accomplished by a combination of pre-incubation heating of embryos for 12 h at 30°C, followed by increasing incubation temperature to 38°C during the first 3 days of incubation. It was further facilitated by increasing turning frequency of the eggs to 48 or 96 times daily. TM during critical phases of muscle development in the late-term chick embryo (E16 to E18) for 3 or 6 hours (39.5°C) had an immediate stimulatory effect on myoblast proliferation that lasted for up to two weeks post-hatch; this was followed by increased hypertrophy at later ages. The various incubation temperatures and TM durations focused on the fine-tuning of muscle development and growth processes during late-term embryogenesis as well as in post-hatch chickens.