scholarly journals Using multielement isotopic analysis to decipher drought impacts and adaptive management in ancient agricultural systems: Fig. 1.

2014 ◽  
Vol 111 (45) ◽  
pp. E4807-E4808 ◽  
Author(s):  
Toby M. Maxwell ◽  
Lucas C. R. Silva ◽  
William R. Horwath
Author(s):  
D.E. Brownlee ◽  
A.L. Albee

Comets are primitive, kilometer-sized bodies that formed in the outer regions of the solar system. Composed of ice and dust, comets are generally believed to be relic building blocks of the outer solar system that have been preserved at cryogenic temperatures since the formation of the Sun and planets. The analysis of cometary material is particularly important because the properties of cometary material provide direct information on the processes and environments that formed and influenced solid matter both in the early solar system and in the interstellar environments that preceded it.The first direct analyses of proven comet dust were made during the Soviet and European spacecraft encounters with Comet Halley in 1986. These missions carried time-of-flight mass spectrometers that measured mass spectra of individual micron and smaller particles. The Halley measurements were semi-quantitative but they showed that comet dust is a complex fine-grained mixture of silicates and organic material. A full understanding of comet dust will require detailed morphological, mineralogical, elemental and isotopic analysis at the finest possible scale. Electron microscopy and related microbeam techniques will play key roles in the analysis. The present and future of electron microscopy of comet samples involves laboratory study of micrometeorites collected in the stratosphere, in-situ SEM analysis of particles collected at a comet and laboratory study of samples collected from a comet and returned to the Earth for detailed study.


2020 ◽  
Vol 9 (4) ◽  
pp. e04942784
Author(s):  
Andrea Aline Mombach ◽  
Carla Grasiele Zanin Hegel ◽  
Rogério Luis Cansian ◽  
Sônia Beatris Balvedi Zakrzevski

The perception of a basic education of the importance of agroecological agricultural systems for human and environmental health is fundamental for changes in consumption habits, the conservation of local biodiversity and long-term social transformation. We analyzed, by utilizing a questionnaire consisting of open and closed questions, the perceptions about agroecological and conventional agricultural production systems in 360 final students of basic education residing in nine Functional Planning Regions of southern Brazil. We used classification categories for answers within thematic axes, expressed in percentages and analyzed by means of Chi-square and Kruskal-Wallis tests. In general, students recognize agroecological systems as healthier for their families and for soil and water conservation, largely because they do not use agrochemicals. However, they demonstrated difficulties when arguing their importance for the conservation of biodiversity, ecosystems and for ensuring the food security of populations. Television was the main source of information related to agroecology, mainly for students residing in rural areas, thus pointing out shortcomings in basic education regarding the approach of the theme in schools. Our results show the need to build a complex network of knowledge and discussions on agroecological agricultural systems in basic education, involving changes in student perceptions, behaviors and sustainable choices.


Author(s):  
William R. Sutton ◽  
Jitendra P. Srivastava ◽  
James E. Neumann ◽  
Peter Droogers ◽  
Brent Boehlert

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