1,487 research outputs found
Lunar recession encoded in tidal rhythmites: a selective overview with examples from Argentina
No full textThe study of tides from the sedimentary record of tidal rhythmites, applying fast Fourier transform analysis, contributes to the understanding of the surficial evolution of our highly dynamic planet, and of the astronomical cycles that influenced the ancient tidal systems. This overview of lunar retreat rates, which includes examples from Argentina, displays a generalized pattern of nonlinear, progressively extended lunar cycles up to the present day. The lunar retreat calculated at different stages of the Earth’s history identifies three time spans of extremely high recession rates, amounting to almost twice that of the present day: Archean–Paleoproterozoic (6.93 cm/year), Neoproterozoic I–Ediacaran (7.01 cm/year) and Ediacaran–early Cambrian (6.48 cm/year). Older comparable recession rates are difficult to recognize because of the lack of tidal rhythmic sequences. The maximum lunar retreat rate is registered after the Copernican meteor bombardment event on the Moon at ~900 Ma, and the time span coincides with the continental dispersal of Rodinia. Every acceleration of the lunar retreat rate coincides with two main processes: (1) meteorite impacts on the Earth or Moon, and (2) reconfiguration of landmasses accompanied by earthquakes that generated changes in the rotational axis of the Earth, inundation surfaces, and glaciation/deglaciation processes. The simultaneous occurrence of such processes makes it difficult to distinguish the causes and effects of each individual process, but its conjunction would have promoted the destabilization of the Earth–Moon system in terms of moment of inertia that was transferred to the Moon rotation.Fil: López, Vanina Lucrecia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Correlación Geológica. Grupo Vinculado al INSUGEO- Centro de Estudios Geologicos Andinos; ArgentinaFil: Azarevich, Miguel Basilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Correlación Geológica. Grupo Vinculado al INSUGEO- Centro de Estudios Geologicos Andinos; Argentin
Lithium and potassium brine deposits from South America: characterization, hydrochemistry, depocenters and resources
No full textLos depósitos de Li y K en salmueras constituyen recursos ácueos caracterizados por una salinidad elevada (> 400% NaCl) y elementos en solución con >350 ppm Li y 0,5-1 % K, acompañados principalmente de Mg, Na, Ca y B. Su génesis está condicionada por la evolución de cuencas endorreicas en clima árido, donde el Li es aportado por lixiviación de rocas circundantes o fuentes termales, y concentrado en los acuíferos por evapotranspiración. En Sudamérica occidental, las condiciones de aridez se desarrollaron a partir del Cretácico, favorecidas por el levantamiento del Altiplano y la Puna y el emplazamiento del arco volcánico andino desde el Mioceno. La configuración de las cuencas corresponde a ante-arco (Atacama) e intra-arco (salares de la Puna), de las cuáles éstas últimas evolucionan a partir de depocentros cretácico-terciarios en Puna Septentrional y como depocentros individuales terciarios en Puna Austral. Los recursos de Li sudamericanos suman el 68% de los mundiales, la producción mundial de LCE es de 82.000 t/a (38% Chile y Argentina), y la capacidad de producción de los salares argentinos es de 400.000 t/a LCE. Este trabajo proporciona una revisión de la evolución de las cuencas salinas desde el límite K-T hasta la actualidad, así como los resultados de la exploración de salmueras de Li y las proyecciones económicas disponibles, en la Puna y el Altiplano.Lithium and K brine deposits constitute water resources characterized by high salinity (> 400% NaCl) and elements in solution in the order of >350 ppm Li and 0.5-1% K, accompanied mainly by Mg, Na, Ca and B. Its genesis is conditioned to the evolution of endorheic basins in arid climates, to which Li is contributed by leaching from surrounding rocks or thermal sources, and concentrated in the aquifers by evapotranspiration. Halite crystallization occurs in the saline nucleus, decreasing the Na+ in solution, enriching itself in Li+ and 7 Li. In western South America, arid conditions developed from the Cretaceous and were enhanced by the uplift of the Altiplano and Puna and the emplacement of the Andean volcanic arc since the Miocene. The basins configuration corresponds to antearc (Atacama) and intra-arc (Puna salars), of which the latter evolve from CretaceousTertiary depocentres in Northern Puna and as individual Tertiary depocentres in Southern Puna. South American Li resources add up to 68% of total resources, global LCE (lithium carbonate equivalent) production is 82,000 t/y (38% Chile and Argentina), and Argentina salars’ production capacity is 400,000 t/y LCE. Lithium is used in the industry of batteries, aluminum and its alloys, glass and ceramics, greases and lubricants, air conditioning, medicine and pharmaceuticals, polymers. Also, 6 Li is used in the production of nuclear energy as a source of tritium, and 7 Li is used as a hydroxide to regulate the pH of the cooling material in the primary circuits of pressurized water nuclear reactors, where it is used as a heat conductor due to its high melting temperature, and as fluoride in molten salt reactors. This paper provides an overall review of salar basins’ evolution from K-T boundary to recent, as well as available Li brine exploration results and economic projections, over the Puna and Altiplano.Fil: López, Vanina Lucrecia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Correlación Geológica. Grupo Vinculado al INSUGEO- Centro de Estudios Geológicos Andinos; Argentina. Universidad Nacional de Salta. Facultad de Cs.naturales. Carrera de Geología; ArgentinaFil: Schalamuk, Bernardo Isidoro. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Instituto de Recursos Minerales. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas. Instituto de Recursos Minerales; ArgentinaFil: Azarevich, Miguel Basilio. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto Superior de Correlación Geológica. Grupo Vinculado al INSUGEO- Centro de Estudios Geologicos Andinos; Argentin
Author Correction: Climatic controls of decomposition drive the global biogeography of forest-tree symbioses
No full text© 2019, The Author(s), under exclusive licence to Springer Nature Limited. In this Letter, the middle initial of author G. J. Nabuurs was omitted, and he should have been associated with an additional affiliation: ‘Forest Ecology and Forest Management Group, Wageningen University and Research, Wageningen, The Netherlands’ (now added as affiliation 182). In addition, the following two statements have been added to the Supplementary Acknowledgements. (1): ‘We would particularly like to thank The French NFI for the work of the many field teams and engineers, who have made extraordinary efforts to make forest inventory data publicly available.’ (1): ‘Sergio de Miguel benefited from a Serra- Húnter Fellowship provided by the Generalitat of Catalonia.’ Finally, the second sentence of the Methods section should have cited the French NFI, which provided a national forestry database used in our analysis, to read as follows: ‘The GFBi database consists of individual-based data that we compiled from all the regional and national GFBi forest-inventory datasets, including the French NFI (IGN—French National Forest Inventory, raw data, annual campaigns 2005 and following, https://inventaire-forestier.ign.fr/spip.php?rubrique159, site accessed on 01 January 2015)’. All of these errors have been corrected online
Status assessment of the Critically Endangered Azores Bullfinch Pyrrhula murina
No full text'This work was part of the Azores Bullfinch monitoring programme included in the project LIFE NAT/P/000013 “Recovery of Azores Bullfinch’s habitat in the Special Protection Area of Pico da Vara / Ribeira do Guilherme”'The Azores Bullfinch is endemic to the island of São Miguel (Azores, Portugal). Its status was uplisted to Critically Endangered in 2005 on the basis of an extremely small and declining population that was considered to be restricted to a very small mountain range (43 km2), in a single location, within which the spread of invasive plants constituted a threat to habitat quality. Nevertheless, information was mostly inferred, or the product of, non-systematic studies. In order to carry out a complete assessment of the conservation status we analysed: (i) population trend, calculated from annual monitoring 1991–2008, (ii) population size, and (iii) range size, obtaining estimates in a single morning study in 2008 involving the simultaneous participation of 48 observers. Contrary to previous inferences, the population is no longer decreasing, although quality of laurel forest habitat continues to decline due to the persistent threat of invasive species. Population size (mean ± SE) was estimated at 1,064 ± 304 individuals using distance sampling methods, although the estimate was very sensitive to the survey method used. Range size estimates (extent of occurrence and area of occupancy) were 144 km2 and 83 km2 respectively. Given the present information, we propose the downlisting of Azores Bullfinch to Endangered on the IUCN Red List.Peer reviewe
Better Resolved Dielectric Dispersions by the Apt Use of Kramers-Kronig Relations, Differential Operators, and All-In-1 Modeling
No full textThe dielectric spectra of colloidal systems and other dielectric media often contain a typical low frequency dispersion, which usually remains unnoticed, because of the presence of strong conduction losses. The KK relations offer a means for converting ' into " data. This allows us to calculate conduction free " spectra in which the l.f. dispersion will show up undisturbed. This interconversion can be done on line with a moving frame of logarithmically spaced ' data. The coefficients of the conversion frames were obtained by kernel matching and by using symbolic differential operators. Logarithmic derivatives and differences of ' and " provide another option for conduction free data analysis. These difference-based functions actually derived from approximations to the distribution function, have the additional advantage of improving the resolution power of dielectric studies. A high resolution is important because of the rich relaxation structure of colloidal suspensions and most other dielectric media. The development of all-in-1 modeling facilitates the conduction free and high resolution data analysis. This mathematical tool allows the apart-together fitting of multiple data and multiple model functions. It proved also useful to go around the KK conversion altogether. This was achieved by the combined approximating ' and " data with a complex rational fractional power function. The all-in-1 minimization turned out to be also highly useful for the dielectric modeling of a suspension with the complex dipolar coefficient. It guarantees a secure correction for the electrode polarization, so that the modeling with the help of the differences ' and " can zoom in on the genuine colloidal relaxations.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Team Kevin Ross
Naturaleza y culturas: reflexiones sobre la “nueva etnografía”. 4-5 Año 1 (2014) septiembre-diciembre. Rutas de Campo. Etnografía de las regiones indígenas de México. 15 años de trabajo
No full textBarabas, Alicia, “La ética del don en Oaxaca: los sistemas indígenas de reciprocidad”, en S. Millán y J. Valle (coords.), La comunidad sin límites: organización social y estructura comunitaria en las regiones indígenas de México, vol. I, México, INAH-Conaculta (Ensayos), 2003.Barabas, Alicia, “Los zapotecos”, en A. Barabas y M. Bartolomé (coords.), Configuraciones étnicas en Oaxaca: perspectivas etnográficas para las autonomías, 3 tt., México, INAH/INI, 1999.Bartolomé, Miguel, “Tradición civilizatoria y diversidad: pasado y presente del pluralismo cultural en Oaxaca”, conferencia inaugural de la VI Mesa Redonda de Monte Albán, México, INAH, 2011.Bartolomé, Miguel, “El pueblo de la lluvia: el grupo etnolingüístico ñu savi (mixtecos)”, en A. Barabas y M. Bartolomé (coords.), Configuraciones étnicas en Oaxaca, México, INAH/INI, t. I, 1999.Bartolomé, Miguel, Gente de costumbre y gente de razón: las identidades étnicas en México, México, Siglo XXI, 1997.Descola, Philippe, Más allá de naturaleza y cultura, Buenos Aires, Amorrortu, 2012 [2005].Descola, Philippe, Las lanzas del crepúsculo: relatos jívaros Alta Amazonia, Buenos Aires, FCE, 2005 [1993].Descola, Philippe, “Construyendo naturalezas: ecología simbólica y práctica social”, en P. Descola y G. Pálsson (coords.), Naturaleza y sociedad, México, Siglo XXI, 2001.Descola, Philippe, La selva culta: simbolismo y práxis en la ecología de los achuar, Quito, Abya-Yala (Pueblos de Ecuador, 3), 1996 [1987].Descola, Philippe y Gísli Pálsson (coords.), Naturaleza y sociedad: perspectivas antropológicas, México, Siglo XXI, 2001 [1996].Durkheim, Émile y Marcel Mauss, “De ciertas formas primitivas de clasificación. Contribución al estudio de las representaciones colectivas”, Obras II: Institución y culto, Seix Barral, Barcelona, 1971 [1903].Lévi-Strauss, Claude, “The Culinary Triangle”, en Carole Counihan y Penny van Esterik, Food and Culture: A Reader, Londres, Routledge, 1997.Lévi-Strauss, Claude, Tristes trópicos, Buenos Aires, Eudeba, 1970.Lévi-Strauss, Claude, Antropología estructural, Buenos Aires, Eudeba, 1968 [1958].Schaden, Egon, Aspectos fundamentais da cultura guaraní, São Paulo, 1954.Tylor, Edward B., Primitive Culture, Londres, Routledge, 1981 [1871].Viveiros de Castro, Eduardo B., A Inconstância da Alma Selvagem e Outros Ensaios de Antropologia, São Paulo, Cosac & Naify, 2002
A new approach to institutional domain analysis: Multilevel research fronts structure
No full textThe intellectual structure and main research fronts of the Faculty of Natural Sciences and
Museum of the National University of La Plata, Argentina is studied, based on the cocitation analysis of subject categories, journals and authors of their scientific publications collected in the Science Citation Index, CD-ROM version, for the period 1991–2000. The objective of this study is to test the utility of those techniques to explore and to visualize the intellectual structure and research fronts of multidisciplinary institutional domains. Special emphasis is laid on the identification of multilevel structures, by means of arrangements of subject categories cocitation analysis and journal cocitation analysis
Studies in the Bromeliaceae, XII
No full textIn the preliminary part the author publishes the news: Hohenbergia guatenialensis L. B. Smith, Piteairnia heterophylla (Lindl.) Beer forma albiflora Standley et L. B. Smith, P. nutckheimii Donn. Smith var. macrolepis L. B. Smith, Tillandsia ionantha Planch. var. scaposa L. B. Smith, T. penlandii L. B. Smith and their var. pedunculata L. B. Smith, T. polita L. B. Smith, Vriesia lancifolia (Baker) L. B. Smith, V. pectinata L. B. Smith and V. racinae L. B. Smith.
In the second part the author continues his synopses of the Tribe Tillandsieae (now subfamily Tillandsioideae according to Harms). In this part he studies the species with simple inflorescences and flowers that all go to one side, with a total of 26 of the genus Vriesia. The first part of the synopses has been published in numbers LXXXVI and CVI of ?Contributions from the Gray Herbariam of Harvard University?
The B corp certification in Germany: an analysis of factors influencing the decertification of B corps
No full textThis paper explores factors provoking certified B Corps to reconsider their certification status in Germany and thus, bridges a research gap on decertification. To investigate this issue, the author follows a qualitative research design that relies on ten semi-structured interviews with company representatives, who provide insights on critical factors and potential pitfalls. Although B Corp certification presents a promising tool, the German B movement is found to be at risk due to its lack of benefits, mainstream transformation, underestimation of renewal and internal stakeholder changes. The implications of the findings are discussed by means of propositions and recommendations for further research. On this basis, B Lab can take timely action and strengthen its vision of “using business as a force for good.
Analysis of watersheds and river systems: short course
No full textShort course: Analysis of Watersheds and River Systems, Session I and II, held on May 28-June 1, 1979 and June 4-June 8, 1979 at Colorado State University, Fort Collins, Colorado.Speakers: Dr. E. V. Richardson, Dr. David Duttweiller, Mr. Lee Mulkey, Dr. Stanley A. Schumm, Dr. Daryl B. Simons, Dr. Ross Carder.Includes bibliographical references.This short course is designed for individuals dealing with the analysis of watersheds and rivers. Practical applications concerning physical processes will be emphasized.Chapter 1. General introduction / Daryl B. Simons and Ruh-Ming Li -- Chapter 2. Introduction to watershed and river analysis / Daryl B. Simons and Ruh-Ming Li -- Chapter 3. Physical processes governing response of watersheds and rivers / Daryl B. Simons, Timothy J. Ward and Ruh-Ming Li -- Chapter 4. Sediment transport / H. W. Shen -- Chapter 5. Alluvial bed roughness / H. W. Shen -- Chapter 6. Overview of flood routing methods / Ruh-Ming Li and V. Miguel Ponce -- Chapter 7. Water routing and yield from watersheds, Part I and II / Ruh-Ming Li, Daryl B. Simons, and Kenneth G. Eggert -- Chapter 8. Water routing in rivers / Yung-Hai Chen -- Chapter 9. Stage discharge relations / Robert K. Simons, Ruh-Ming Li, and Daryl B. Simons -- Chapter 10. Watershed sediment yield / Ruh-Ming Li, Daryl B. Simons, and Timothy J. Ward -- Chapter 11. Unsteady sediment routing models in rivers / Yung-Hai Chen and Daryl B. Simons -- Chapter 12. Known discharge sediment routing / Glenn O. Brown and Ruh-Ming Li -- Chapter 13. Landslide potential delineation / Timothy J. Ward, Ruh-Ming Li, and Daryl B. Simons -- Chapter 14. Application of Kalman filtering in watershed and river analysis / Nguyen Duong -- Chapter 15. Handheld calculator programs for analysis / Kenneth G. Eggert, Ruh-Ming Li, and Daryl B. Simons -- Chapter 16. Overview of case studies and data management / Daryl B. Simons, Ruh-Ming Li, and Nguyen Duong -- Chapter 17. Canal and channel design and river response analysis / Daryl B. Simons, Ruh-Ming Li, and Yung-Hai Chen -- Chapter 18. Degradation and aggradation analysis / Ruh-Ming Li and Daryl B. Simons -- Chapter 19. Watershed best management analysis / Ruh-Ming Li, Timothy J. Ward, and Daryl B. Simons -- Chapter 20. Large river basin analysis: Yazoo River Sedimentation Study / Daryl B. Simons and Ruh-Ming Li
- …
