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  • Chemistry  (50,887)
  • Cell & Developmental Biology  (6,449)
  • Inorganic Chemistry  (3,614)
  • GEOPHYSICS  (3,293)
  • 2020-2024  (46)
  • 1990-1994  (60,584)
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  • 1
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    EDP SCIENCES
    Publication Date: 2024-04-05
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 2
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    EDP SCIENCES
    Publication Date: 2024-04-05
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 3
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    EDP SCIENCES
    Publication Date: 2024-04-07
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 4
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    EDP SCIENCES
    Publication Date: 2024-04-05
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 5
    Publication Date: 2024-04-05
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 6
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    EDP SCIENCES
    Publication Date: 2024-04-08
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 7
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    EDP SCIENCES
    Publication Date: 2024-04-05
    Description: Chemistry;Materials science
    Keywords: Chemistry ; Materials science ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 8
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    EDP SCIENCES
    Publication Date: 2024-04-05
    Description: Chemistry
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: French
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  • 9
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Mineralogy includes thirteen chapters that discuss the methodology of specific mineralogical methods, the composition of minerals from different igneous rocks, and the composition of minerals from different sedimentary rocks.It contains detailed mineralogical studies from Africa, Asia, and Europe. Chapters present different scientific mineralogical methods and detailed descriptions of minerals from different magmatic and sedimentary rocks.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNV Chemistry of minerals, crystals and gems
    Language: English
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  • 10
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Benzimidazole is a comprehensive survey of the known and new methods of benzimidazole synthesis, the spectral and theoretical aspects of existing benzimidazole derivatives, and the anticancer properties of a new class of benzimidazole derivatives. This book examines aspects and newer mechanisms of benzimidazoles containing heterocyclic moiety. Chapters report on anticancer properties of benzimidazole derivatives, novel methods of synthesis of benzimidazoles, versatile nature of the benzimidazoles, spectral and theoretical studies of benzimidazole derivatives, and medicinal importance and pharmacological aspects of benzimidazole derivatives.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Language: English
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  • 11
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Green Chemistry - New Perspectives is at the frontiers of this continuously evolving interdisciplinary science, and publishes research that attempts to reduce the environmental impact of the chemical enterprise by developing a technology base that is inherently non-toxic to living things and the environment. The book covers all aspects of green chemistry, including chemical synthesis, nano synthesis, eco-friendly processes, biomass, extraction techniques, environmental remediation, and energy, making it a unique reference resource. This will continue to encourage scientists around the world to develop novel synthetic methods or improve the existing ones to circumvent some of the problems and favours all aspects of green chemistry. This book is intended for academia, professionals, scientists, as well as graduate and undergraduate students without any geographical limitations.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Language: English
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  • 12
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: This book consists of several selected chapters on important subjects in modern high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC). The content addresses aspects related to both improvements in the mainstream HPLC/UPLC technology and utilization, as well as developments of exploratory new materials and equipment. The book presents useful details about the presented subjects as well as describes new applications and/or relevant case studies for each subject. It is addressed to a large audience of analytical chemists involved in separation science. Each chapter is authored by scientists with considerable field and academic experience.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Language: English
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  • 13
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Recent Advances in Chemical Kinetics provides a comprehensive overview of several types of chemical reactions. It includes six chapters that discuss solvent catalysis, customized flow reactors, p-conjugation in kinetics, kinetics of autoxidation, molecular chameleon for cations and anions, and internal clocks of atoms.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry
    Language: English
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  • 14
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Redox reactions are involved in biochemistry, energy, corrosion, and much more. In both biology and electrochemistry, the redox reaction is complex and varied. For example, redox shuttles in supercapacitors show aspects of molecular electrochemistry applied to electrode porosity. In pseudocapacitors, the formalism associated with their electrochemical response requires investigation and formalism. Similarly, the simple definition of redox potential opens fundamental questions about its measurement in solutions without supporting salts. This book illustrates the variety of redox reactions in its examination of the importance of redox molecules in the development of new electrical energy storage devices.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRH Electrochemistry and magnetochemistry
    Language: English
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  • 15
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: We are living in a critical time, both for humanity and the planet, which has led us to look for more sustainable formulas to interact with the environment. One of the important changes in the design and operation of chemical processes is the search for environmentally friendly technologies. Supercritical carbon dioxide has been revealed as a promising environmentally friendly solvent that is energy efficient, selective and capable of reducing waste, making it a promising alternative to conventional organic solvents. However, reliable and versatile mathematical models of phase equilibrium thermodynamics are needed for the use of supercritical carbon dioxide in process design and viability studies. This book reviews experimental procedures for obtaining high-pressure phase equilibria data and describes the phase diagrams of binary mixtures and some thermodynamic models capable of determining the conditions of phase equilibria at high pressures. These concepts are applied to the components of the transesterification reaction of rac-2-pentanol with a vinyl ester, which is important in the pharmaceutical industry because (S)-2-pentanol can be obtained as a reaction product. This product is a key intermediate in the synthesis of drugs against Alzheimer’s disease.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry
    Language: English
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  • 16
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: In recent decades, artificial porous structures have attracted increasing enthusiasm from researchers inspired by the fascinating molecular pores in nature and their unique biological functions. Although substantial achievements in porous materials have been realized, the construction of topologically designed pores is still challenging. Recently, the emergence of covalent organic frameworks (COFs), which are constructed based on organic and polymer chemistry, has made it possible to design artificial pores with controlled pore size, topology and interface properties. COFs are crystalline porous materials constructed by the precise reticulation of organic building blocks via dynamic covalent bonds. Distinct from non-covalent interactions which tend to produce isostructures, covalent bonds enable accurate pore design owing to their predetermined reaction pathways. In addition, the appropriate polycondensation of organic building units enables the formation of extended two-dimensional (2D) and three-dimensional (3D) polymer architectures with periodically ordered skeletons and well-defined pores. With their large surface area, tailorable structures, and tunable chemistry, COFs are regarded as potentially superior candidates for various applications including catalysis, energy storage and conversion, mass transport and biotechnology. This book examines the historic achievement of COFs, providing clear and comprehensive guidance for researchers on their structural design, synthetic protocols and functional exploration.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Language: English
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  • 17
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Fluoride covers a continuum of topics that are frequently studied in the broad area of fluoride (F) research. It provides an overview of the primary sources of environmental fluoride in typical high-fluoride environments and demonstrates the transitions and transformations that emerge and culminate in hydro-geochemical interactions that result in fluoride-fouling of large portions of the world’s water and agricultural resources. This way, the book pinpoints the connection between F enrichment of water sources and the prevalence of endemic fluorosis in certain areas of the world. In order to contribute to a better understanding of the global fluoride problem, new fluoride detection and quantification technologies are proposed with an in-depth analysis of emerging trends in the use of portable user-friendly devices in point-of-use measurements of water fluoride. This has been presented against the backdrop of a robust overview of traditional fluoride quantification methodologies that are still in wide application among the scientific communities. In addressing fluoride toxicities, which are not limited to dental and skeletal dilapidations, the authors have explored the role of natural antioxidants in ameliorating physiological fluoride-induced noxious effects in mammalian systems. Nonetheless, since community dependence on high-fluoride water due to a lack of alternative clean water sources remains to be the principal pathway of human fluoride over-exposure, a review chapter on F mitigation techniques applied all over the world is incorporated aiming at providing a succinct overview of water defluoridation techniques and strategies being used to combat the impacts of human F overexposure around the globe. Since every cloud has a silvery lining, the possibility of using ammonium fluorides as a novel reagent in mineral processing has been considered convenient industrial fluorinating agents, which present the possibility of complete regeneration that is not afforded by the reagents presently used in decomposing silicon component of the ores.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNK Inorganic chemistry
    Language: English
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  • 18
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: This book discusses the chemistry and applications of pyridine derivatives. The library of pyridine derivatives is growing steadily with numerous synthetic analogues already described and the identification of new, naturally occurring pyridine-based compounds. The book includes ten chapters organized into two parts. The first part focuses on the numerous types of reactions that arise from pyridine derivatives. The second part examines the pharmaceutical applications of pyridine derivatives as well as their usefulness as sensors for metal cations and extracting agents for platinum group metals.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Language: English
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  • 19
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: The book discusses multiple issues associated with modern dosimetry in physics and treatment planning and how investigators from diverse world centers and institutions approach problem-solving in these important areas. It examines topics including pretreatment validation and factors affecting reference dosimetry. It also addresses unique issues affecting pediatric populations as well as the modern role of thermoluminescence validation. Several chapters discuss intensity modulation, including defining modern problems associated with both treatment planning and the definition of tumor and normal tissue contours. Furthermore, the book examines the role of imaging as both a vehicle to define tumor targets and normal tissue as well as a tool for dose validation.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRL Nuclear chemistry, photochemistry and radiation
    Language: English
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  • 20
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: The book comprises 14 chapters covering all the issues related to water desalination. These chapters emphasize the relationship between problems encountered with the use of feed water, the processes developed to address them, the operation of the required plants and solutions actually implemented. This compendium will assist designers, engineers and investigators to select the process and plant configuration that are most appropriate for the particular feed water to be used, for the geographic region considered, as well as for the characteristics required of the treated water produced. This survey offers a comprehensive, hierarchical and logical assessment of the entire desalination industry. It starts with the worldwide scarcity of water and energy, continues with the thermal - and membrane-based processes and, finally, presents the design and operation of large and small desalination plants. As such, it covers all the scientific, technological and economical aspects of this critical industry, not disregarding its environmental and social points of view. One of InTech's books has received widespread praise across a number of key publications. Desalination, Trends and Technologies (Ed. Schorr, M. 2011) has been reviewed in Corrosion Engineering, Science & Technology – the official magazine for the Institute of Materials, Minerals & Mining, and Taylor & Francis's Desalination Publications. Praised for its “multi-faceted content [which] contributes to enrich it,” and described as “an essential companion...[that] enables the reader to gain a deeper understanding of the desalination industry,” this book is testament to the quality improvements we have been striving towards over the last twelve months.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Language: English
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  • 21
    Publication Date: 2024-04-05
    Description: The Global Methane Initiative (GMI) is a voluntary international partnership that promotes methane recovery and reuse activities in developing and transition economies. The U.S. Department of State requested an evaluation of the activities and outcomes supported in whole or in part by its contributions to GMI to gauge its value added to the program.
    Keywords: Physics ; Environmental Science ; Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TQ Environmental science, engineering and technology ; thema EDItEUR::R Earth Sciences, Geography, Environment, Planning::RB Earth sciences::RBP Meteorology and climatology
    Language: English
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  • 22
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Progress in agricultural, biomedical and industrial applications' is a compilation of recent advances and developments in gas chromatography and its applications. The chapters cover various aspects of applications ranging from basic biological, biomedical applications to industrial applications. Book chapters analyze new developments in chromatographic columns, microextraction techniques, derivatisation techniques and pyrolysis techniques. The book also includes several aspects of basic chromatography techniques and is suitable for both young and advanced chromatographers. It includes some new developments in chromatography such as multidimensional chromatography, inverse chromatography and some discussions on two-dimensional chromatography. The topics covered include analysis of volatiles, toxicants, indoor air, petroleum hydrocarbons, organometallic compounds and natural products. The chapters were written by experts from various fields and clearly assisted by simple diagrams and tables. This book is highly recommended for chemists as well as non-chemists working in gas chromatography.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Language: English
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  • 23
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: This book discusses electrocatalysis and electrocatalysts for energy, water electrolysis, water treatment, CO2 conversion, and green chemistry. It reviews various electrocatalysts and their properties and electrochemical performances. The first section of the book covers topics in direct alcohol fuel cells including Pt-based electrocatalysts as non-carbon electrode support materials and the development of electrocatalysts for direct methanol fuel cells. The second section of the book covers various topics in electrocatalysis and electrocatalysts for a cleaner environment, including electrocatalysts for the conversion of CO2 to valuable products and SYNGAS, electrocatalysts for water electrolysis, and much more.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRH Electrochemistry and magnetochemistry
    Language: English
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  • 24
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Surfactants are ubiquitous and have applications in diverse areas, including food, cosmetics, detergents, lubricants, enhanced oil recovery (EOR), and targeted drug delivery systems. Their wide diversity of applications owes to their unique structure, namely, a hydrophilic and a hydrophobic group present in the same molecule. Although most surfactants used industrially are synthetic, there is a growing need for natural surfactants, as the latter is obtainable from renewable sources and are less toxic and highly biodegradable in contrast to their synthetic counterparts. This book is a compilation of interesting articles by various experts that cover various applications of both synthetic and natural surfactants.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRC Colloid chemistry
    Language: English
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  • 25
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: The chemical sensor plays an essential role in the fields of environmental conservation and monitoring, disaster and disease prevention, and industrial analysis. A typical chemical sensor is a device that transforms chemical information in a selective and reversible way, ranging from the concentration of a specific sample component to total composition analysis, into an analytically useful signal. Much research work has been performed to achieve a chemical sensor with such excellent qualities as quick response, low cost, small size, superior sensitivity, good reversibility and selectivity, and excellent detection limit. This book introduces the latest advances on chemical sensors. It consists of 15 chapters composed by the researchers active in the field of chemical sensors, and is divided into 5 sections according to the classification following the principles of signal transducer. This collection of up-to-date information and the latest research progress on chemical sensor will provide valuable references and learning materials for all those working in the field of chemical sensors.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Language: English
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  • 26
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Distillation is an important separation technique that has been used for many centuries to exploit the volatility differences between components in a mixture. The distillation process has many variations and applications. This book includes two sections on desalination and reactive distillation. It discusses desalination in the processes of solar and membrane distillation, with a focus on the reduction of energy costs to obtain potable water. It also discusses reactive distillation, which can be used in some cases to reduce the power duty in the separation process by using the reaction heat directly in the separation. The book includes cases of mathematical modeling, simulation, and optimization of the distillation process.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry
    Language: English
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  • 27
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Cyclodextrins (CDs) have attracted great interest from the research community as well as industries in an array of sectors because of their unique structural features. This book provides a comprehensive overview of CDs, beginning with their historical background. Chapters address such topics as the structure and physiochemical properties of CDs, advancements in the field, and potential applications of these materials in fields such as drug delivery and sensing. This book reveals new frontiers in the CD world and is a useful resource for organic, analytical, and supramolecular chemists as well as scientists engaged in biological and material sciences.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry::PNNP Polymer chemistry
    Language: English
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  • 28
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: The book presents a comprehensive overview of sorption, which is a multi-parametric separation process. It is extensively used in the removal of various pollutants from the tertiary stage of wastewater treatment, from leachates, etc. It discusses fundamental points of the technique as well as kinetic theories and isotherms. It also examines the synthesis and characterizations of all studied adsorbent materials to find their paths of sorption. Finally, it highlights the importance of having a cost-estimation plan for the synthesis of sorbent materials as well as predictions for their reusability.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNR Physical chemistry::PNRX Surface chemistry and adsorption
    Language: English
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  • 29
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Carotenoids are natural and versatile secondary metabolites, most of them showing colours that vary from yellow to red. They are widespread among living beings where they are involved in many biological roles reporting beneficial actions. To date, more than 750 carotenoids have been described in nature. Humans cannot synthesize carotenoids de novo, thus they are mainly obtained through diet. In fact, carotenoids are consistently found in tissues or biological fluids where they play a beneficial decreasing the risk of developing some diseases.During the last half-century, significant advances in carotenoids research have been made. This book highlights new perspectives and applications of carotenoids including characterization and isolation of new compounds (including rare carotenoids), their production at a mid-large scale (involving new innovative approaches), and uses of carotenoids in different biotechnological fields like food science, biomedicine, and cosmetics.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNN Organic chemistry
    Language: English
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  • 30
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    IntechOpen | IntechOpen
    Publication Date: 2024-04-05
    Description: Infrared Spectroscopy - Perspectives and Applications is a compendium of contributions from experts in the field of infrared (IR) spectroscopy. This assembly of investigations and reviews provides a comprehensive overview of the fundamentals as well as the groundbreaking applications in the field. Chapters discuss IR spectroscopy applications in the food and biomedicine sectors and for measuring transport through polymer membranes, characterizing lignocellulosic biomasses, detecting adulterants, and characterizing enamel surface advancements. This book is an invaluable resource and reference for students, researchers, and other interested readers.
    Keywords: Chemistry ; thema EDItEUR::P Mathematics and Science::PN Chemistry::PNF Analytical chemistry::PNFS Spectrum analysis, spectrochemistry, mass spectrometry
    Language: English
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  • 31
    Publication Date: 2023-03-08
    Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in LeClerc, H., Tompsett, G., Paulsen, A., McKenna, A., Niles, S., Reddy, C., Nelson, R., Cheng, F., Teixeira, A., & Timko, M. Hydroxyapatite catalyzed hydrothermal liquefaction transforms food waste from an environmental liability to renewable fuel. IScience, 25(9), (2022): 104916, https://doi.org/10.1016/j.isci.2022.104916.
    Description: Food waste is an abundant and inexpensive resource for the production of renewable fuels. Biocrude yields obtained from hydrothermal liquefaction (HTL) of food waste can be boosted using hydroxyapatite (HAP) as an inexpensive and abundant catalyst. Combining HAP with an inexpensive homogeneous base increased biocrude yield from 14 ± 1 to 37 ± 3%, resulting in the recovery of 49 ± 2% of the energy contained in the food waste feed. Detailed product analysis revealed the importance of fatty-acid oligomerization during biocrude formation, highlighting the role of acid-base catalysts in promoting condensation reactions. Economic and environmental analysis found that the new technology has the potential to reduce US greenhouse gas emissions by 2.6% while producing renewable diesel with a minimum fuel selling price of $1.06/GGE. HAP can play a role in transforming food waste from a liability to a renewable fuel.
    Description: This work was funded by the DOE Bioenergy Technology Office (DE-EE0008513), a DOE DBIR (DE-SC0015784) and the MassCEC. The authors thank WenWen Yao, Department of Environmental Science at WPI, for TOC analysis, Mainstream Engineering for heating value characterization of the oil and solid samples, Wei Fan for assistance in obtaining SEM images and, Julia Martin and Ronald Grimm for their assistance in collecting XPS data, and Jeffrey R. Page for his assistance with oil upgrading and analysis. HOL was partially funded for this work by NSF Graduate Research Fellowship award number 2038257. A portion of this work was performed at the National High Magnetic Field Laboratory Ion Cyclotron Resonance user facility, which is supported by the NSF Division of Materials Research and Division of Chemistry through DMR 16-44779 and the State of Florida.
    Keywords: Chemistry ; Chemical engineering ; Catalysis
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 32
    Publication Date: 2024-04-05
    Description: Chemiebezogene Kompetenzen werden bereits im Sachunterricht der Grundschule entwickelt und sollen im Chemieunterricht der Sekundarstufe I aufgegriffen und weiterentwickelt werden. Ziel dieser Studie war es, die chemiebezogenen Kompetenzen der Schülerinnen und Schüler in der Übergangsphase zwischen Sachunterricht und Chemieunterricht zu analysieren. In einer Ergänzungsstudie wurden zusätzlich sowohl die Auswirkungen der Schulschließungen aufgrund der SARS-CoV-II Pandemie auf die Kompetenzen der Schülerinnen und Schüler als auch der Einfluss einer veränderten Testadministration untersucht. Insgesamt wurden die Kompetenzen von 2262 Lernenden der Jahrgangsstufen 5 bis 9 zu drei Messzeitpunkten analysiert. Die Ergebnisse zeigen, dass die chemiebezogenen Kompetenzen sowohl zum Ende der Grundschulzeit als auch zu Beginn des Chemieunterrichts über alle Kompetenzbereiche hinweg sehr heterogen ausfallen. Dennoch sind sie zu Beginn des Chemieunterrichts in einigen Kompetenzbereichen höher ausgeprägt als zum Ende der Grundschulzeit. Nach den pandemiebedingten Schulschließungen waren die Kompetenzen ähnlich ausgeprägt wie in den gleichen Jahrgangsstufen vor den Schulschließungen. Eine während der Schulschließungen notwendige Bearbeitung der Testhefte von zu Hause aus führte vor allem bei den jüngeren Schülerinnen und Schülern zu besseren Testergebnissen als die Bearbeitung in der Schule. Um die Entwicklung chemiebezogener Kompetenzen in der Übergangsphase zu optimieren, sollte der Erwerb dieser Kompetenzen bereits im Sachunterricht einheitlicher gestaltet werden.
    Keywords: Science ; Chemistry ; Education ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::J Society and Social Sciences::JN Education
    Language: German
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  • 33
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    Logos Verlag Berlin | Logos Verlag Berlin
    Publication Date: 2024-04-05
    Description: In 2005, the hybrid model was published by Prof. H.-D. Alber and Prof. P. Zhu as an alternative to the Allen-Cahn model for the description of phase field transformations. With low interfacial energy, it is more efficient, since the resolution of the diffuse interface is numerically broader for the same solution accuracy and allows coarser meshing. The solutions of both models are associated with energy minimisation and in this work the error terms introduced in the earlier publications are discussed and documented using one and two dimensional numerical simulations. In the last part of this book, phase field problems, initially not coupled with material equations, are combined with linear elasticity and, after simple introductory examples, a growing martensitic inclusion is simulated and compared with literature data. In addition to the confirmed numerical advantage, another phenomenon not previously described in the literature is found: with the hybrid model, in contrast to the examples calculated with the Allen-Cahn model, an inclusion driven mainly by curvature energy does not disappear completely. The opposite problem prevents inclusions from growing from very small initial configurations, but this fact can be remedied by a very finely chosen diffuse interface width and by analysing and adjusting the terms that generate the modelling errors. The last example shows that the hybrid model can be used with numerical advantages despite the above mentioned peculiarities.
    Keywords: Science ; Chemistry ; Mathematics ; Science ; Physics ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PB Mathematics ; thema EDItEUR::P Mathematics and Science::PH Physics
    Language: English
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  • 34
    Publication Date: 2024-04-05
    Description: Das selbstgesteuerte Experimentieren ist laut den nationalen Bildungsstandards sowie den Lehrplänen im Fach Chemie ein wichtiger Bestandteil der naturwissenschaftlichen Schulbildung. Offene Experimentierformen sind jedoch wenig etabliert. Um das selbstgesteuerte Experimentieren in die Unterrichtspraxis zu implementieren, wurde im Rahmen dieses Forschungsprojekts eine eintägige Lehrkräftefortbildung zur Konzeption von selbstgesteuerten Experimenten im Chemieunterricht durchgeführt. Dazu wurde ein literaturbasiertes Strukturierungskonzept entwickelt, mit dem die Lehrkräfte kochbuchartige Schulversuche zu selbstgesteuerten und kompetenzorientierten Experimenten mit beliebigen Öffnungsgraden modifizieren können. Begleitend zur Fortbildung wurde im Prä-Post-Follow-Up-Design das fachdidaktische Wissen der Teilnehmenden hinsichtlich der Planung von selbstgesteuerten Experimenten empirisch überprüft. Zur Erfassung dieses Konstrukts wurde ein neues Messinstrument literaturbasiert entwickelt und die Güte des Messinstruments evaluiert. Die Auswertungen zeigen, dass die Fortbildung hinsichtlich des fachdidaktischen Wissens der Lehrkräfte kurz- sowie langfristig lernförderlich ist und die Fortbildung von den Teilnehmenden positiv bewertet wird. Die Reliabilitätsanalyse sowie die Validierungsstudie zeigen, dass der Test sowohl reliabel als auch valide ist. In Folgestudien könnte die langfristige Verhaltensänderung der Lehrkräfte bezüglich der Implementierung des selbstgesteuerten Experimentierens in den Unterricht untersucht werden.
    Keywords: Science ; Chemistry ; Science ; Education ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PD Science: general issues ; thema EDItEUR::J Society and Social Sciences::JN Education
    Language: German
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  • 35
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    Logos Verlag Berlin | Logos Verlag Berlin
    Publication Date: 2024-04-05
    Description: Konsumgüter werden beispielsweise mit Slogans wie "Gut in Bio. Schlecht in Chemie." beworben. Dabei wird intendiert, sich gezielt von "Chemie" abzugrenzen und sich das positive Bild von "Natur" zu Nutze zu machen. Dies prägt die öffentliche Meinung und trägt zu einer antagonistisch-wertenden Sicht von "Chemie" und "Natur" bei. Dass Chemie als Naturwissenschaft der Beschreibung der Natur dient, um deren Stoffe und Stoffumwandlungen zu erklären, ist dem Laien selten bewusst. Chemie findet überall statt, insbesondere in der Natur! Genau an diesem Punkt setzt das Unterrichtskonzept "Chemie Pur - Unterrichten in der Naturglqq an. Ziel ist es, im Freiland, mit direkt vor Ort gewonnenen Naturstoffen, Umweltprozesse experimentell zu erarbeiten. Die projektbegleitende Evaluationsstudie stellte sich der Forschungsfrage, wie sich das Unterrichtskonzept auf das Fach- und Sachinteresse, auf die Naturverbundenheit sowie auf die Einstellung zu Chemie und Natur von Schülerinnen und Schülern der Sekundarstufe II auswirkt. Die Auswertung der Fragebogenergebnisse mit latenten Veränderungsmodellen haben gezeigt, dass die Intervention im Freiland das inhaltsbezogene Sachinteresse steigert und die Einstellung zu Chemie und Natur positiv beeinflusst sowie ein erhöhten Fachwissenszuwachs ermöglicht. Die gewonnenen Erkenntnisse können die Grundlage für die Entwicklung und Evaluation von good-practice-Ansätzen naturwissenschaftlicher Lernsituationen bilden. Das Unterrichtskonzept Chemie Pur leistet zudem einen Beitrag im Bereich Outdoor Education, um den Antagonismus von Chemie und Natur zu verringern.
    Keywords: Science ; Chemistry ; Science ; Education ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::P Mathematics and Science::PD Science: general issues ; thema EDItEUR::J Society and Social Sciences::JN Education
    Language: German
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  • 36
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    The MIT Press | The MIT Press
    Publication Date: 2024-03-27
    Description: The original 1818 text of Mary Shelley's classic novel, with annotations and essays highlighting its scientific, ethical, and cautionary aspects. Mary Shelley's Frankenstein has endured in the popular imagination for two hundred years. Begun as a ghost story by an intellectually and socially precocious eighteen-year-old author during a cold and rainy summer on the shores of Lake Geneva, the dramatic tale of Victor Frankenstein and his stitched-together creature can be read as the ultimate parable of scientific hubris. Victor, “the modern Prometheus,” tried to do what he perhaps should have left to Nature: create life. Although the novel is most often discussed in literary-historical terms—as a seminal example of romanticism or as a groundbreaking early work of science fiction—Mary Shelley was keenly aware of contemporary scientific developments and incorporated them into her story. In our era of synthetic biology, artificial intelligence, robotics, and climate engineering, this edition of Frankenstein will resonate forcefully for readers with a background or interest in science and engineering, and anyone intrigued by the fundamental questions of creativity and responsibility. This edition of Frankenstein pairs the original 1818 version of the manuscript—meticulously line-edited and amended by Charles E. Robinson, one of the world's preeminent authorities on the text—with annotations and essays by leading scholars exploring the social and ethical aspects of scientific creativity raised by this remarkable story. The result is a unique and accessible edition of one of the most thought-provoking and influential novels ever written. Essays by Elizabeth Bear, Cory Doctorow, Heather E. Douglas, Josephine Johnston, Kate MacCord, Jane Maienschein, Anne K. Mellor, Alfred Nordmann
    Keywords: science fiction ; gothic ; horror ; European ; British ; literature ; fiction ; cautionary tale ; STEM ; science ; bioethics ; classic ; bicentennial ; Josephine Johnston ; Cory Doctorow ; Jane Maienschein ; Kate MacCord ; Alfred Nordmann ; Elizabeth Bear ; Anne K. Mellor ; Heather E. Douglas ; Frankenstein ; Creature ; Monster ; Mary Shelley ; Makers ; women in science ; science and anti-science ; values in science ; responsible innovation ; Industrial Revolution ; Mary Wollstonecraft ; William Godwin ; Percy Bysshe Shelley ; Galvanism ; Mount Tambora ; Myths ; Two Cultures ; epistolary novel ; Victor Frankenstein ; Geneva ; Prometheus ; Arctic ; Lord Byron ; John Polidori ; ghost stories ; Revisions ; Electricity ; Lightning ; Vitalism ; Chemistry ; Extinction ; Magnetism ; Moral responsibility ; Legal responsibility ; Social responsibility ; Consequences ; Obligations ; Ethics ; Maker Culture ; DIY ; Technology Adjacent Possible ; Facebook ; Surveillance ; Aristotle ; Fetal development ; Epigenesis ; Embryo ; Person ; Technoscience ; Alchemy ; uncanny valley ; animation ; complexity ; Morality ; Monstrosity ; Christianity ; Otherness ; Gender ; Nature ; Domestic Affections ; Women ; Sexuality ; Technical Sweetness ; Los Alamos ; Trinity Test ; Scientific Responsibility ; Nuclear Weapons ; adjacent possible ; synthetic biology ; robotics ; thema EDItEUR::F Fiction and Related items::FB Fiction: general and literary::FBC Classic fiction: general and literary ; thema EDItEUR::F Fiction and Related items::FL Science fiction::FLC Classic science fiction
    Language: English
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  • 37
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    Logos Verlag Berlin | Logos Verlag Berlin
    Publication Date: 2024-04-05
    Description: When auralizing moving sound sources in Virtual Reality (VR) environments, the two main input parameters are the location and radiated signal of the source. An array measurement-based model is developed to characterize moving sound sources regarding the two parameters in this thesis. This model utilizes beamforming, i.e. delay and sum beamforming (DSB) and compressive beamforming (CB) to obtain the locations and signals of moving sound sources. A spiral and a pseudorandom microphone array are designed for DSB and CB, respectively, to yield good localization ability and meet the requirement of CB. The de-Dopplerization technique is incorporated in the time-domain DSB to address moving source problems. Time-domain transfer functions (TDTFs) are calculated in terms of the spatial locations within the steering window of the moving source. TDTFs then form the sensing matrix of CB, thus allowing CB to solve moving source problem. DSB and CB are further extended to localize moving sound sources, and the reconstructed signals from the beamforming outputs are investigated to obtain the source signals. Moreover, localization and signal reconstruction are evaluated through varying parameters in the beamforming procedures, i.e. steering position, steering window length and source speed for a moving periodic signal using DSB, and regularization parameter, signal to noise ratio (SNR), steering window length, source speed, array to source motion trajectory and mismatch for a moving engine signal using CB. The parameter studies show guidelines of parameter selection based on the given situations in this thesis for modeling moving source using beamforming. Both algorithms are able to reconstruct the moving signals in the given scenarios. Although CB outperforms DSB in terms of signal reconstruction under particular conditions, the localization abilities of the two algorithms are quite similar. The practicability of the model has been applied on pass-by measurements of a moving loudspeaker using the designed arrays, and the results can match the conclusions drawn above from simulations. Finally, a framework on how to apply the model for moving source auralization is proposed.
    Keywords: Science ; Chemistry ; Technology & Engineering ; Construction ; Technology & Engineering ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TN Civil engineering, surveying and building::TNK Building construction and materials ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TB Technology: general issues
    Language: English
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  • 38
    Publication Date: 2024-04-05
    Description: Neuere Erkenntnisse zum Umsatzverhalten an Dieseloxidationskatalysatoren (DOCs) zeigen, dass das Umsatzverhalten von Schadstoffen vom Oxidationsgrad der verwendeten Edelmetallkatalysatoren abhängen kann. Dabei wird deutlich, dass sich der Oxidationsgrad bei typischen Abgaszusammensetzungen langsam und reversibel mit der Katalysatortemperatur ändert. Das kann bei periodischen Katalysatortemperaturänderungen zu einem ausgeprägten Hystereseverhalten führen. Bisherige Ergebnisse liegen insbesondere zum Verhalten der NO-Oxidation an Platin-Katalysatoren vor. Ziel der vorliegenden Arbeit ist es daher, die Untersuchungen auf seriennahe Pd- und PtPd-Mischkatalysatoren sowie auf andere abgastypische Schadstoffe, wie CO und Kohlenwasserstoffe, zu erweitern und dabei auch den Einfluss der Katalysatoralterung zu erfassen. Es wurde ein globalkinetisches Modell entwickelt und an die experimentellen Befunde angepasst. Dabei zeigte sich, dass es in der Regel möglich ist, das Umsatzverhalten bei reinen Pt- und Pd-Katalysatoren mit diesem örtlich eindimensionalen, makrokinetischen Zweiphasenmodell zutreffend zu beschreiben, wohingegen das Verhalten auf Pt/Pd-Mischkatalysatoren weniger gut simuliert werden kann. Dies ist vermutlich auf die heterogene Struktur der Pt/Pd-legierten Partikel zurückzuführen.
    Keywords: Science ; Chemistry ; Technology & Engineering ; Chemical & Biochemical ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TD Industrial chemistry and manufacturing technologies::TDC Industrial chemistry and chemical engineering
    Language: German
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  • 39
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    Frontiers Media SA
    Publication Date: 2024-04-04
    Description: The Frontiers in Chemistry Editorial Office team are delighted to present the inaugural “Frontiers in Chemistry: Rising Stars” article collection, showcasing the high-quality work of internationally recognized researchers in the early stages of their independent careers. All Rising Star researchers featured within this collection were individually nominated by the Journal’s Chief Editors in recognition of their potential to influence the future directions in their respective fields. The work presented here highlights the diversity of research performed across the entire breadth of the chemical sciences, and presents advances in theory, experiment and methodology with applications to compelling problems. This Editorial features the corresponding author(s) of each paper published within this important collection, ordered by section alphabetically, highlighting them as the great researchers of the future. The Frontiers in Chemistry Editorial Office team would like to thank each researcher who contributed their work to this collection. We would also like to personally thank our Chief Editors for their exemplary leadership of this article collection; their strong support and passion for this important, community-driven collection has ensured its success and global impact.
    Keywords: Green and Sustainable Chemistry ; Analytical Chemistry ; Theoretical and Computational Chemistry ; Polymer Chemistry ; Medicinal and Pharmaceutical Chemistry ; Organic Chemistry ; Nanoscience ; Catalysis and Photocatalysis ; Supramolecular Chemistry ; Electrochemistry ; Inorganic Chemistry ; Chemical Biology ; thema EDItEUR::P Mathematics and Science::PD Science: general issues
    Language: English
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  • 40
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    Taylor & Francis | CRC Press
    Publication Date: 2024-03-31
    Description: Hydroxyapatite coatings are of great importance in the biological and biomedical coatings fields, especially in the current era of nanotechnology and bioapplications. With a bonelike structure that promotes osseointegration, hydroxyapatite coating can be applied to otherwise bioinactive implants to make their surface bioactive, thus achieving faster healing and recovery. In addition to applications in orthopedic and dental implants, this coating can also be used in drug delivery. Hydroxyapatite Coatings for Biomedical Applications explores developments in the processing and property characterization and applications of hydroxyapatite to provide timely information for active researchers and newcomers alike. In eight carefully reviewed chapters, hydroxyapatite experts from the United States, Japan, Singapore, and China present the latest on topics ranging from deposition processes to biomedical applications in implants and drug delivery. This book discusses: Magnetron sputtering and electrochemical deposition The modification of hydroxyapatite properties by sol–gel deposition to incorporate other elements found in natural bones, such as zinc, magnesium, and fluorine The use of pure hydroxyapatite in drug delivery applications The growth or self-assembly of hydroxyapatite on shape memory alloy Hydroxyapatite composite coatings—with carbon nanotubes, titanium dioxide (TiO2), and others—on the titanium alloy Offering valuable insights and a wealth of data, including numerous tables and figures, this is a rich source of information for research on hydroxyapatite coatings. Each chapter also covers material that provides an accessible stepping stone for those who are new to the field.
    Keywords: Pre-clinical medicine: basic sciences ; Chemistry ; Materials science ; thema EDItEUR::M Medicine and Nursing::MF Pre-clinical medicine: basic sciences ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 41
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    MDPI - Multidisciplinary Digital Publishing Institute
    Publication Date: 2024-04-05
    Description: Nanofibers, particularly those of a carbonaceous content, have received increased interest in the past two decades due to their outstanding physico-chemical characteristics and their possibility to form and contribute towards a plethora of potentially advantageous materials for consumer, industrial and medical applications. Despite this, and together with the numerous research studies and published articles that have sought to investigate these aspects, the potential impact of CNTs is still not understood. Whether or not nanofibers may be able to provide a sophisticated alternative to conventional materials is still debatable, whilst their effects upon both environmental and human health are highly equivocal. How nanofibers are conceived can determine how they may interact with different environments, such as the human body. Understanding each key step of the synthesis and production of nanofibers to their use within potential applications is therefore essential in gaining an insight into how they may be perceived by any biological system and environment. Thus, obtaining such information will enable all scientific communities to begin to realize the potential advantages posed by nanofibers. The aim of this Special Issue therefore, was to provide a collective overview of nanofibers; ‘from synthesis to application’. The Issue particularly focuses upon carbon-based nanofibers, but also highlights alternative nanofiber types. Emphasis is given holistically, with articles discussing the production routes of nanofibers, their plight during their life-cycle (origin to applied form and effects over time), as well as how nanofibers could either incite conflict, or provide aid to human and environmental health.
    Keywords: QD1-999 ; Toxicology ; Chemistry ; Biology ; Material Science ; Nanofibers ; Nanotechnology ; thema EDItEUR::P Mathematics and Science::PN Chemistry
    Language: English
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  • 42
    Publication Date: 2024-04-04
    Description: This volume, occasioned by the centenary of the Fritz Haber Institute, formerly the Institute for Physical Chemistry and Electrochemistry, covers the institute's scientific and institutional history from its founding until the present. The institute was among the earliest established by the Kaiser Wilhelm Society, and its inauguration was one of the first steps in the development of Berlin-Dahlem into a center for scientific research. Its establishment was made possible by an endowment from Leopold Koppel, granted on the condition that Fritz Haber, well-known for his discovery of a method to synthesize ammonia from its elements, be made its director. The history of the institute has largely paralleled that of 20th-century Germany. It undertook controversial weapons research during World War I, followed by a "Golden Era" during the 1920s, in spite of financial hardships.
    Keywords: Chemistry ; Chemistry ; Fritz Haber Institute ; thema EDItEUR::P Mathematics and Science::PD Science: general issues::PDX History of science
    Language: English
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  • 43
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    transcript Verlag | transcript Verlag
    Publication Date: 2024-04-04
    Description: Die Chemie büßt zugunsten physikalischer und lebenswissenschaftlicher Konzeptionen zunehmend an Deutungsmacht über die molekulare Welt ein. Sandra Lang untersucht, inwiefern die Ausdifferenzierung der chemischen Wissenschaften mit sich ebenfalls ausdifferenzierenden Zugriffen auf das Molekulare zusammenhängt. Anhand der vier exemplarischen Grenzfelder Materialwissenschaften, Biomedizin, Pharmazie und Quantenchemie und deren Narrative zur molekularen Eigenschaft der Chiralität veranschaulicht sie die transformative Phase der Chemie angesichts sich wandelnder Innovationsdispositive.
    Keywords: Chemie ; Chiralität ; Molekülkonzept ; Naturwissenschaften ; Grenzarbeit ; Interdisziplinarität ; Hybridität ; Wissenschaft ; Technik ; Wissenschaftssoziologie ; Techniksoziologie ; Wissenssoziologie ; Wissenschaftsgeschichte ; Soziologie ; Chemistry ; Chirality ; Molecule Concept ; Natural Sciences ; Border Work ; Interdisciplinarity ; Hybridity ; Science ; Technology ; Sociology of Science ; Sociology of Technology ; Sociology of Knowledge ; History of Science ; Sociology ; thema EDItEUR::P Mathematics and Science::PD Science: general issues::PDR Impact of science and technology on society ; thema EDItEUR::J Society and Social Sciences::JH Sociology and anthropology::JHB Sociology
    Language: German
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  • 44
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    De Gruyter | De Gruyter
    Publication Date: 2024-04-11
    Description: Presents technologies and key concepts to produce suitable smart materials and intelligent structures for sensing, information and communication technology, biomedical applications (drug delivery, hyperthermia therapy), self-healing, flexible memories and construction technologies. Novel developments of environmental friendly, cost-effective and scalable production processes are discussed by experts in the field.
    Keywords: Science ; Chemistry ; Industrial & Technical ; Technology & Engineering ; Textiles & Polymers ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TD Industrial chemistry and manufacturing technologies::TDC Industrial chemistry and chemical engineering ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TG Mechanical engineering and materials::TGM Materials science
    Language: English
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  • 45
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    De Gruyter | De Gruyter
    Publication Date: 2024-04-05
    Description: Comprise definition of 1500 terms. Innovation from A to Z presents a glossary, including: Terms, older terms whose meanings have changed, acronyms, synonyms, famous names, selected abbreviations, and cross-references. A highly interdisciplinary approach incorporating strategy and entrepreneurship with technology and engineering sciences, economics, marketing, organizational behavior and theory. Ideal for engineers, managers, sales people and economists. Innovation Technology from A to Z Glossary of terms, including acronyms, synonyms, abbreviations, cross-references 1500 terms supplemented by figures and tables that clearly demonstrate the state-of-the-art in Innovation Technology
    Keywords: Science ; Chemistry ; Technology & Engineering ; Agriculture ; thema EDItEUR::P Mathematics and Science::PN Chemistry ; thema EDItEUR::T Technology, Engineering, Agriculture, Industrial processes::TV Agriculture and farming
    Language: English
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  • 46
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    Coimbra University Press
    Publication Date: 2022-01-31
    Description: This work brings together various contributions from experts in very diverse areas of knowledge, to discuss the theme ‘Light’ from various points of view. The subjects gathered in this work come from the areas of Physics, Philosophy, Transcendence, Chemistry, Optics, Literature, History of Sciences, History, Geography, International Relations, Biology, Psychology, Art, Cinema and Photography, Medicine and Museology. The texts partially reflect the contents presented at the interdisciplinary colloquium ‘Visões da Luz’ held in October 2015, on the occasion of the International Year of Light 2015, under the aegis of III-UC and open to academia and society, to teachers of the Basic and Secondary Education.
    Keywords: Geography ; Chemistry ; Literature ; Geology ; Light ; Optics ; Biology ; History ; Physics
    Language: Portuguese
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  • 47
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 1994-04-01
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Flam, F -- New York, N.Y. -- Science. 1994 Apr 1;264(5155):32-3.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/8140417" target="_blank"〉PubMed〈/a〉
    Keywords: AIDS Vaccines/*chemical synthesis/immunology ; Animals ; Antibodies, Viral/biosynthesis ; Cellobiose ; Chemistry ; HIV Antibodies/biosynthesis ; Herpesvirus 4, Human/*immunology ; Societies, Scientific ; *Vaccines, Synthetic/immunology ; Viral Proteins ; Viral Vaccines/*chemical synthesis/immunology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 48
    Publication Date: 2011-08-24
    Description: A 54.95-MHz coherent backscatter radar, an ionosonde and the magnetometer located at Trivandrum in India (8.5 deg N, 77 deg E, 0.5 deg N dip angle) recorded large-amplitude ionospheric fluctuations and magnetic field fluctuations associated with a Pc5 micropulsation event, which occurred during an intense magnetic storm on 24 March 1991 (A(sub p) = 161). Simultaneous 100-n T-level fluctuations are also observed in the H-component at Brorfelde, Denmark (55.6 deg N gm) and at Narsarsuaq, Greenland (70.6 deg N gm). Our study of the above observations shows that the E-W electric field fluctuations in the E- and F-regions and the magnetic field fluctuations at Thumba are dominated by a near-sinusoidal oscillation of 10 min during 1730-1900 IST (1200-1330 UT), the amplitude of the electric field oscillation in the equatorial electrojet (EEJ) is 0.1-0.25 mV/m and it increases with height, while it is about 1.0 mV/m in the F-region, the ground-level H-component oscillation can be accounted for by the ionospheric current oscillation generated by the observed electric field oscillation in the EEJ and the H-component oscillations at Trivandrum and Brofelde are in phase with each other. The observations are interpreted in terms of a compressional cavity mode resonance in the inner magnetosphere and the assoicated ionospheric electric field penetrating from high latitudes to the magnetic equator.
    Keywords: GEOPHYSICS
    Type: Annales Geophysicae (ISSN 0992-7689); 12; 6; p. 565-573
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  • 49
    Publication Date: 2011-08-24
    Description: The Coast Ranges of the Cascadia margin are overriding the subducted Juan de Fuca/Gorda plate. We investigate the extent to which the latitudinal change in attributes related to the subduction process. These attributes include the varibale age of the subducted slab that underlies the Coast Ranges and average vertical crustal velocities of the western margin of the Coast Rnages for two markedly different time periods, the last 45 years and the last 100 kyr. These vertical crustal velocities are computed from the resurveying of highway bech marks and from the present elevation of shore platforms that have been uplifted in the late Quaternary, respectively. Topogarphy of the Coast Ranges is in part a function of the age and bouyancy of the underlying subducted plate. This is evident in the fact that the two highest topographic elements of the Coast Rnages, the Klamath Mountains and the Olympic Mountains, are underlain by youngest subducted oceanic crust. The subducted Blanco Fracture Zone in southernmost Oregon is responsible for an age discontinuity of subducted crust under the Klamath Mountains. The norhtern terminus of hte topographically higher Klamaths is offset to the north relative to the position of the underlying Blanco Fracture Zone, teh offset being in the direction of migration of the farcture zone, as dictated by relative plate motions. Vertical crustal velocities at the coast, derived from becnh mark surveys, are as much as an order of magnitude greater than vertical crustal velocities derived from uplifted shore platforms. This uplift rate discrepancy indicates that strain is accumulating on the plate margin, to be released during the next interplate earthquake. In a latitudinal sense, average Coast Rnage topography is relatively high where bench mark-derived, short-term vertical crustal velocities are highest. Becuase the shore platform vertical crustal velocities reflect longer-term, premanent uplift, we infer that a small percentage of the interseismic strain that accumulates as rapid short-term uplift is not recovered by subduction earthquakes but rather contributes to rock uplift of the Coast Ranges. The conjecture that permanent rock uplift is related to interseismic uplift is consistent with the observation that those segments of the subduction zone subject to greater interseismic uplift rates are at approximately the same latitudes as those segments of the Coast Ranges that have higher magnitudes of rock uplift over the long term.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B6; p. 12,245-12,255
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  • 50
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    In:  Other Sources
    Publication Date: 2011-08-24
    Description: A comprehensive review is presented of the mathematical models used to represent magnetic fields in the Earth's magnetosphere, of the way existing data-based models use these methods and of the associated problems and concepts. The magnetic field has five main components: the internal field, the magnetopause, the ring current, the tail and Birkeland currents. Methods of representing separately each of these are discussed, as is the deformation of magnetic fields; Appendix B traces the connection between deformations and the Cauchy integral. A summary section lists the uses of data-based models and their likely future evolution, and Appendix A supplements the text with a set of problems.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A9; p. 17,169-17,198
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  • 51
    Publication Date: 2011-08-24
    Description: We present a map of the coseimic displacement field resulting from the Landers, California, June 28, 1992, earthquake derived using data acquired from an orbiting high-resolution radar system. We achieve results more accurate than previous space studies and similar in accuracy to those obtained by conventional field survey techniques. Data from the ERS 1 synthetic aperture radar instrument acquired in April, July, and August 1992 are used to generate a high-resolution, wide area map of the displacements. The data represent the motion in the direction of the radar line of sight to centimeter level precision of each 30-m resolution element in a 113 km by 90 km image. Our coseismic displacement contour map gives a lobed pattern consistent with theoretical models of the displacement field from the earthquake. Fine structure observed as displacement tiling in regions several kilometers from the fault appears to be the result of local surface fracturing. Comparison of these data with Global Positioning System and electronic distance measurement survey data yield a correlation of 0.96; thus the radar measurements are a means to extend the point measurements acquired by traditional techniques to an area map format. The technique we use is (1) more automatic, (2) more precise, and (3) better validated than previous similar applications of differential radar interferometry. Since we require only remotely sensed satellite data with no additioanl requirements for ancillary information. the technique is well suited for global seismic monitoring and analysis.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B10; p. 19,617-19,635
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  • 52
    Publication Date: 2011-08-24
    Description: New line parameters for two heavy odd nitrogen molecules HNO3 in the nu(sub 5)/2nu(sub 9) region, and ClONO2 in the nu(sub 4) region are incorporated in the analysis of high resolution i.r. atmospheric spectra. The line parameters are tested and renormalized vs laboratory spectra, and then applied to retrievals from balloon-borne and ground-based solar absorption spectra.
    Keywords: GEOPHYSICS
    Type: Journal of Quantitative Spectroscopy & Radiative Transfer (ISSN 0022-4073); 52; 3-4; p. 367-377
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  • 53
    Publication Date: 2011-08-24
    Description: The spectroscopic identification for the HNO3 3 nu(sub 9) - nu(sub 9) band Q branch at 830.4/cm is reported based on 0.01/cm resolution solar occultation spectra of the lower stratosphere recorded by the Atmospheric Trace Molecule Spectroscopy (ATMOS) Fourier transform spectrometer and a recent analysis of this band. Least-squares fits to 0.0025/cm resolution laboratory spectra in the Q branch region indicate an integrated intensity of 0.529 x 10(exp -18)/cm/mol/sq cm at 296 K for this weak band. Stratospheric HNO3 retrievals derived from the ATMOS data are consistent with this value within its estimated uncertainty of about +/- 30%. A set of spectroscopic line parameters suitable for atmospheric studies has been generated.
    Keywords: GEOPHYSICS
    Type: Journal of Quantitative Spectroscopy & Radiative Transfer (ISSN 0022-4073); 52; 3-4; p. 319-322
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  • 54
    Publication Date: 2011-08-24
    Description: About 200 i.r. solar spectra recorded at 0.01/cm resolution on 71 days between November 1991 and July 1993 at the Network for the Detection of Stratospheric Change (NDSC) station at Mauna Loa, Hawaii (latitude 19.53 deg N, longitude 155.58 deg W, elevation 3.459 km) have been analyzed with a nonlinear least-squares spectral fitting technique to study temporal variations in the total column of atmospheric ethane (C2H6) above the site. The results were derived from the analysis of the unresolved nu(sub 7) band (P)Q(sub 3) subbranch at 2976.8/cm. A distinct seasonal cycle is observed with a factor of 2 variation, a maximum total column of 1.16 x 10(exp 16) mol/sq cm at the end of winter, and a minimum total column of 0.53 x 10(exp 16) mol/sq cm at the end of summer. Our measurements are compared with previous observations and model predictions.
    Keywords: GEOPHYSICS
    Type: Journal of Quantitative Spectroscopy & Radiative Transfer (ISSN 0022-4073); 52; 3-4; p. 273-279
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  • 55
    Publication Date: 2011-08-24
    Description: Quantitative measurements of the wavelength dependence of aerosol extinction in the 750-3400/cm spectral region have been derived from 0.01/cm resolution stratospheric solar occultation spectra recorded by the ATMOS (Atmospheric Trace Molecule Spectroscopy) Fourier transform spectrometer about 9 1/2 months after the Mt Pinatubo volcanic eruption. Strong, broad aerosol features have been identified near 900, 1060, 1190, 1720, and 2900/cm below a tangent height of approximately 30 km. Aerosol extinction measurements derived from approximately 0.05/cm wide microwindows nearly free of telluric line absorption in the ATMOS spectra are compared with transmission calculations derived from aerosol size distribution profiles retrieved from correlative SAGE (Stratospheric Aerosol and Gas Experiment) II visible and near i.r. extinction measurements, seasonal and zonally averaged H2SO4 aerosol weight percentage profiles, and published sulfuric acid optical constants derived from room temperature laboratory measurements. The calculated shapes and positions of the aerosol features are generally consistent with the observations, thereby confirming that the aerosols are predominantly concentrated H2SO4-H2O droplets, but there are significant differences between the measured and calculated wavelength dependences of the aerosol extinction. We attribute these differences as primarily the result of errors in the calculated low temperature H2SO4-H2O optical constants. Errors in both the published room temperature optical constants and the limitations of the Lorentz-Lorenz relation are likely to be important.
    Keywords: GEOPHYSICS
    Type: Journal of Quantitative Spectroscopy & Radiative Transfer (ISSN 0022-4073); 52; 3-4; p. 241-252
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  • 56
    Publication Date: 2011-08-24
    Description: We present vertical column abundances of H2O, N2O, HNO3, NO2, O3, HF, HCl, and ClNO3, determined from solar absorption spectra measured by the JPL MkIV interferometer from the NASA DC-8 aircraft. These observations, taken in 1987 and 1992, covered latitudes ranging from 85 deg S to 85 deg N. Although most gases display latitude symmetry, large asymmetries in H2O, HNO3, and O3 are apparent, which can be ascribed to processes enhanced by the colder Antarctic winter temperatures.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 23; p. 2599-2602
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  • 57
    Publication Date: 2011-08-24
    Description: Simultaneous in situ measurements of NO2, NO, O3, ClO, pressure and temperature have been made for the first time, presenting a unique opportunity to test our current understanding of the photochemistry of the lower stratospere. Data were collected from several flights of the ER-2 aircraft at mid-latitudes in May 1993 during NASA's Stratospheric Photochemistry, Aerosols and Dynamics Expedition (SPADE). The daytime ratio of NO2/NO remains fairly constant at 19 km with a typical value of 0.68 and standard deviation of +/- 17. The ratio observations are compared with simple steady-state calculations based on laboratory-measured reaction rates and modeled NO2 photolysis rates. At each measurement point the daytime NO2/NO with its measurements uncertainty overlap the results of steady-state caculations and associated uncertainty. Possible sources of error are examined in both model and measurements. It is shown that more accurate laboratory determinations of the NO + 03 reaction rate and of the NO2 cross-sections in the 200-220 K temperature range characteristic of the lower stratosphere would allow for a more robust test of our knowledge of NO(X) phtochemistry by reducing significant sources if uncertainties in the interpretation of statospheric measurements.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 23; p. 2555-2558
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  • 58
    Publication Date: 2011-08-24
    Description: The ability to predict short-term variations in the Earth's rotation has gained importance in recent years owing to more precise spacecraft tracking requirements. Universal time (UT1), that component of the Earth's orientation corresponding to the rotation angle, can be measured by number of high-precision space geodetic techniques. A Kalman filter developed at the Jet Propulsion Laboratory (JPL) optimally combines these different data sets and generates a smoothed times series and a set of predictions for UT1, as well as for additional Earth orientation components. These UT1 predictions utilize an empirically derived random walk stochastic model for the length of the day (LOD) and require frequent and up-to-date measurements of either UT1 or LOD to keep errors from quickly accumulating. Recent studies have shown that LOD variations are correlated with changes in the Earth's axial atmospheric angular momentum (AAM) over timescales of several years down to as little as 8 days. AAM estimates and forecasts out to 10 days are routinely available from meteorological analysis centers; these data can supplement geodetic measurements to improve the short-term prediction of LOD and have therefore been incorporated as independent data types in the JPL Kalman filter. We find that AAM and, to a lesser extent, AAM forecast data are extremely helpful in generating accurate near-real-time estimates of UT1 and LOD and in improving short-term predictions of these quantities out to about 10 days.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B4; p. 6981-6996
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  • 59
    Publication Date: 2011-08-24
    Description: Disk-shaped current distributions are useful tools in modeling the magnetospheres of Earth and other planets and have also been adapted for modeling the geotail. Such models usually start with an axisymmetric vector potential but may be modified to account for observed asymmetries, variable thickness, and warping in response to an inclined orientation of the planetary dipole axis. Models of this type until now either have lacked the ability to simulate a sharp inner edge of the current and to control accurately its falloff with distance or did not allow a simple analytical representation. Here existing methods will be reviewed, after which a new class of models which overcomes the above deficiencies and also allows the modeling of current disks of finite thickness flanked by current-free regions will be presented.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A1; p. 199-205
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  • 60
    Publication Date: 2011-08-24
    Description: An improved model of Earth's gravitational field, Goddard Earth Model T-3 (GEM-T3), has been developed from a combination of satellite tracking, satellite altimeter, and surface gravimetric data. GEM-T3 provides a significant improvement in the modeling of the gravity field at half wavelengths of 400 km and longer. This model, complete to degree and order 50, yields more accurate satellite orbits and an improved geoid representation than previous Goddard Earth Models. GEM-T3 uses altimeter data from GEOS 3 (1975-1976), Seasat (1978) and Geosat (1986-1987). Tracking information used in the solution includes more than 1300 arcs of data encompassing 31 different satellites. The recovery of the long-wavelength components of the solution relies mostly on highly precise satellite laser ranging (SLR) data, but also includes Tracking Network (TRANET) Doppler, optical, and satellite-to-satellite tracking acquired between the ATS 6 and GEOS 3 satellites. The main advances over GEM-T2 (beyond the inclusion of altimeter and surface gravity information which is essential for the resolution of the shorter wavelength geoid) are some improved tracking data analysis approaches and additional SLR data. Although the use of altimeter data has greatly enhanced the modeling of the ocean geoid between 65 deg N and 60 deg S latitudes in GEM-T3, the lack of accurate detailed surface gravimetry leaves poor geoid resolution over many continental regions of great tectonic interest (e.g., Himalayas, Andes). Estimates of polar motion, tracking station coordinates, and long-wavelength ocean tidal terms were also made (accounting for 6330 parameters). GEM-T3 has undergone error calibration using a technique based on subset solutions to produce reliable error estimates. The calibration is based on the condition that the expected mean square deviation of a subset gravity solution from the full set values is predicted by the solutions' error covariances. Data weights are iteratively adjusted until this condition for the error calibration is satisfied. In addition, gravity field tests were performed on strong satellite data sets withheld from the solution (thereby ensuring their independence). In these tests, the performance of the subset models on the withheld observations is compared to error projections based on their calibrated error covariances. These results demonstrate that orbit accuracy projections are reliable for new satellites which were not included in GEM-T3.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B2; p. 2815-2839
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  • 61
    Publication Date: 2011-08-24
    Description: We present predictions of the signatures of magnetosheath particle precipitation (in the regions classified as open low-latitude boundary layer, cusp, mantle and polar cap) for periods when the interplanetary magnetic field has a southward component. These are made using the 'pulsating cusp' model of the effects of time-varying magnetic reconnection at the dayside magnetopause. Predictions are made for both low-altitude satellites in the topside ionosphere and for midaltitude spacecraft in the magnetosphere. Low-altitude cusp signatures, which show a continuous ion dispersion signature, reveal 'quasi-steady reconnection' (one limit of the pulsating cusp model), which persists for a period of at least 10 min. We estimate that 'quasi-steady' in this context corresponds to fluctuations in the reconnection rate of a factor of 2 or less. The other limit of the pulsating cusp model explains the instantaneous jumps in the precipitating ion spectrum that have been observed at low altitudes. Such jumps are produced by isolated pulses of reconnection: that is, they are separated by intervals when the reconnection rate is zero. These also generate convecting patches on the magnetopause in which the field lines thread the boundary via a rotational discontinuity separated by more extensive regions of tangential discontinuity. Predictions of the corresponding ion precipitation signatures seen by midaltitude spacecraft are presented. We resolve the apparent contradiction between estimates of the width of the injection region from midaltitude data and the concept of continuous entry of solar wind plasma along open field lines. In addition, we reevaluate the use of pitch angle-energy dispersion to estimate the injection distance.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); p. 8531-8553
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  • 62
    Publication Date: 2011-08-24
    Description: Simultaneous profiles of aerosol backscatter ratio were measured over Lauder, New Zealand (45 deg S, 170 deg E) on the night of November 24, 1992. Instrumentation comprised two complementary lidar systems and a backscattersonde, to give measurements at wavelengths 351, 490, 532, and 940 nm. The data from the lidars and the backscattersonde were self-consistent, enabling the wavelength dependence of aerosol backscatter to be determined as a function of altitude. This wavelength-dependence is a useful parameter in radiative transfer calculations. In the stratosphere, the average wavelength exponent between 351 and 940 nm was -1.23 +/- 0.1, which was in good agreement with values derived from measured physical properties of aerosols.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 9; p. 789-792
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  • 63
    Publication Date: 2011-08-24
    Description: High-energy electrons have been measured systematically in a low-altitude (520 x 675 km), nearly polar (inclination = 82 deg) orbit by sensitive instruments onboard the Solar, Anomalous, and Magnetospheric Particle Explorer (SAMPEX). Count rate channels with electron energy thresholds ranging from 0.4 MeV to 3.5 MeV in three different instruments have been used to examine relativistic electron variations as a function of L-shell parameter and time. A long run of essentially continuous data (July 1992 - July 1993) shows substantial acceleration of energetic electrons throughout much of the magnetosphere on rapid time scales. This acceleration appears to be due to solar wind velocity enhancements and is surprisingly large in that the radiation belt 'slot' region often is filled temporarily and electron fluxes are strongly enhanced even at very low L-values (L aprroximately 2). A superposed epoch analysis shows that electron fluxes rise rapidly for 2.5 is approximately less than L is approximately less than 5. These increases occur on a time scale of order 1-2 days and are most abrupt for L-values near 3. The temporal decay rate of the fluxes is dependent on energy and L-value and may be described by J = Ke-t/to with t(sub o) approximately equals 5-10 days. Thus, these results suggest that the Earth's magnetosphere is a cosmic electron accelerator of substantial strength and efficiency.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 6; p. 409-412
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  • 64
    Publication Date: 2011-08-24
    Description: Rocket data have been used to evaluate the characteristics of precipitating relativistic electrons and their effects on the electrodynamic structure of the middle atmosphere. These data were obtained at Poker Flat, Alaska, on May 13 and 14, 1990, during a midday, highly relativistic electron (HRE) precipitation event. Solid state detectors were used to measure the electron fluxes and their energy spectra. An X ray scintillator was included on each flight to measure bremsstrahlung X rays produced by energetic electrons impacting on the upper atmosphere. However, these were found the be of negligible importance for this particular event. The energy deposition by the electrons has been determined from the flux measurements and compared with in situ measurements of the atmospheric electrical response. The electrodynamic measurements were obtained by the same rockets and additionally on May 13, with an accompanying rocket. The impact flux was highly irregular, containing short-lived bursts of relativistic electrons, mainly with energies below 0.5 MeV and with fluxes most enhanced between pitch angles of 0 deg - 20 deg. Although the geostationary counterpart of this measured event was considered to be of relatively low intensity and hardness, energy deposition peaked near 75 km with fluxes approaching an ion pair production rate in excess of 100/cu cm s. This exceeds peak fluxes in relativistic electron precipitation (REP) events as observed by us in numerous rocket soundings since 1976. Conductivity measurements from a blunt probe showed that negative electrical conductivities exceeded positive conductivities down to 50 km or lower, consistent with steady ionization by precipitating electrons above 1 MeV. These findings imply that the electrons from the outer radiation zone can modulate the electrical properties of the middle atmosphere to altitudes below 50 km. During the decline and activity minimum of the current solar cycle, we anticipate the occurence of similar events but with fluxes 1-2 orders of magnitude above that reported here, based on studies of earlier solar cycles (e.g., Baker et al., 1993).
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; D10; p. 21,071-21,081
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  • 65
    Publication Date: 2011-08-24
    Description: Nitrous oxide (N2O) measured on board the ER-2 aircraft during the Airborne Arctic Stratospheric Expedition 2 (AASE 2) has been used to monitor descent of air inside the Arctic vortex between October 1991 and March 1992. Monthly mean N2O fields are calculated from the flight data and then compared with mean fields calculated from the high-resolution Geophysical Fluid Dynamics Laboratory general circulation model SKYHI in order to evaluate the model's simulation of the polar vortex. From late fall through winter the model vortex evolves in much the same way as the 1991-1992 vortex, with N2O gradients at the edge becoming progressively steeper. The October to March trends in N2O profiles inside the vortex are used to verify daily net heating rates in the vortex that were computed from clear sky radiative heating rates and National Meteorological Center temperature observations. The computed heating rates successfully estimate the descent of vortex air from December through February but suggest that before December, air at high latitudes may not be isolated from the midlatitudes. SKYHI heating rates are in good agreement with the computed rates but tend to be slightly higher (i.e., less cooling) due to meteorological differences between SKYHI and the 1991-1992 winter. Three ER-2 flights measured N2O just north of the subtropical jet. These low-midlatitude profiles show only slight differences from the high-midlatitude profiles (45 deg - 60 deg N), indicating strong meridional mixing in the midlatitude 'surf zone.' Mean midwinter N2O profiles inside and outside the vortex calculated from AASE 2 data are shown to be nearly identical to 1989 AASE profiles, pointing to the N2O/potential temperature relationship as an excellent marker for vortex air.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; D10; p. 20,713-20,723
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  • 66
    Publication Date: 2011-08-24
    Description: The combined Nimbus 7 solar backscattered ultraviolet (SBUV) and NOAA 11 SBUV/2 ozone data, covering a period of more than a solar cycle (about 15 years), are used to study the UV response of ozone in the stratosphere. The study shows that about 2% change in total column ozone and about 5-7% change in ozone mixing ratio in the upper stratosphere (0.7 to 2 hPa) may be attributed to the change in the solar UV flux over a solar cycle. In the upper stratosphere, where photochemical processes are expected to play a major role, the measured solar cycle variation of ozone is significantly larger than inferred either from the photochemical models or from the ozone response to the 27-day solar UV modulation. For example, the observed solar cycle related change in ozone mixing ratio at 2 hPa is about 1% for 1% change in the solar UV flux near 200 nm. The inferred change in ozone from either the photochemical models or from the 27-day ozone-UV response is about a factor of 2-3 lower than this value.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; D10; p. 20,665-20,671
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  • 67
    Publication Date: 2011-08-24
    Description: Vertical profiles of N2O and NO(y) taken by the ER-2 outside the vortex are used to construct average vertical profiles of F(NO(y)) = NO(y)/(A-N2O), where A is the tropospheric content of N2O three years prior to the measurements. The southern hemisphere had less nitrous oxide in the range 400 less than Theta less than 470 K, by up to 25% relative to the northern hemisphere. F(NO(y)) is the ratio of NOy produced to N2O lost in a stratospheric air mass since entry from the troposphere. The profiles of F(NO(y)) have the following characteristics: (1) Relative to 1991-1992, a year without denitrification inside or outside the vortex, the northern hemisphere in 1988-1989 showed denitrification outside the vortex ranging up to 25% and averaging 17% above Theta = 425 K. (2) Relative to the northern hemisphere in 1991-1992, the southern hemisphere in 1987 showed denitrification outside the vortex ranging up to 32% and averaging 20% above Theta = 400 K. (3) Below Theta = 400 K the southern hemisphere showed enhancements of F(NO(y)) relative to the northern hemisphere in 1991-1992 ranging up to 200% at Theta = 375 K, outside the vortex. Corresponding profiles of residual water, R(H2O) = H2O - 2(1.6 - CH4), are considered and shown to be consistent with those of F(NO(y)) in the sense that they show deficits outside the Antarctic vortex, which was both dehydrated and denitrified, but not outside the 1988-1989 Arctic vortex, which was denitrified but not dehydrated. R(H2O) is the water content of stratospheric air with the contribution from methane oxidation subtracted. Comparison of F(NO(y)) and R(H2O) below 400 K outside the Antarctic vortex leads to the suggetion that dehydration in the Antarctic vortex occurs by the sedimentation of ice crystals large enough to fall out of the stratosphere, whereas denitrification occurs mainly on mixed nitric acid-water crystals which evaporate below the base of the vortex at Theta = 400 K but above the tropopause.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; D10; p. 20,573-20,583
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  • 68
    Publication Date: 2011-08-24
    Description: During January and August 1985, the scanning radiometers of the Earth Radiation Budget Experiment(ERBE) aboard the Earth Radiation Budget Satellite (ERBS) and the NOAA-9 satellite were operated in along-track scanning modes. Along-track scanning permits the study of many measurement problems. It provides the data for developing a limb-darkening model for a single site over a short period of time and also permits the indentification of the scene from data taken at smaller nadir angles. The earth-emitted radiation measured by the scanners has been analyzed to produce limb-darkening models for a variety of scene types. Limb-darkening models relate the radiance in any given direction to the radiant flux. The scene types were computed using measurements within 10 deg of zenith. The models have values near zenith of 1.02-1.09. The typical zenith values of the model are 1.06 for both day and night for ERBS, and for NOAA-9, 1.06 for day and 1.05 for night. Mean models are formed for the ERBS and NOAA-9 results and are found to differ less than 1%, the ERBS results being the higher. The models vary about 1% with latitude near zenith and agree with earlier models that were used to analyze ERBE data typically to 2%.
    Keywords: GEOPHYSICS
    Type: Journal of Applied Meteorology (ISSN 0894-8763); 33; 1; p. 74-84
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  • 69
    Publication Date: 2011-08-24
    Description: One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. In investigating the causes of geomagnetic storms occurring during solar maximum, the following topics are discussed: solar phenomena; types of solar wind; magnetic reconnection and magnetic storms; an interplanetary example; and future space physics missions.
    Keywords: GEOPHYSICS
    Type: EOS (ISSN 0096-3941); 75; 5; p. 49, 51-53
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  • 70
    Publication Date: 2011-08-24
    Description: Atmospheric mass loading produces a primarily vertical displacement of the Earth's crust. This displacement is correlated with surface pressure and is large enough to be detected by very long baseline interferometry (VLBI) measurements. Using the measured surface pressure at VLBI stations, we have estimated the atmospheric loading term for each station location directly from VLBI data acquired from 1979 to 1992. Our estimates of the vertical sensitivity to change in pressure range from 0 to -0.6 mm/mbar depending on the station. These estimates agree with inverted barometer model calculations (Manabe et al., 1991; vanDam and Herring, 1994) of the vertical displacement sensitivity computed by convolving actual pressure distributions with loading Green's functions. The pressure sensitivity tends to be smaller for stations near the coast, which is consistent with the inverted barometer hypothesis. Applying this estimated pressure loading correction in standard VLBI geodetic analysis improves the repeatability of estimated lengths of 25 out of 37 baselines that were measured at least 50 times. In a root-sum-square (rss) sense, the improvement generally increases with baseline length at a rate of about 0.3 to 0.6 ppb depending on whether the baseline stations are close to the coast. For the 5998-km baseline from Westford, Massachusetts, to Wettzell, Germany, the rss improvement is about 3.6 mm out of 11.0 mm. The average rss reduction of the vertical scatter for inland stations ranges from 2.7 to 5.4 mm.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B9; p. 18,081-18,087
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  • 71
    Publication Date: 2011-08-24
    Description: A theoretical model is used to describe and investigate the effects of simultaneous crystallization, radiation loss, and entrainment of cooler material on the temperature of a well-mixed core of an active aa lava flow. Entrainment of crust, levee debris, and base material into the interior of active flows has been observed, but the degree of assimilation and the thermal consequences are difficult to quantify. The rate of entrainment can be constrained by supplementing the theoretical model with information on the crystallization along the path of the flow and estimation of the radiative loss from the flow interior. Application of the model is demonstrated with the 1984 Mauna Loa flow, which was erupted about 30 C undercooled. Without any entrainment of cooler material, the high crystallization rates would have driven temperatures in the core wall above temperatures measured by thermocouple and estimated from glass geothermometry. One plausible scenario for this flow, which agrees with available temperature and crystallinity measurements, has a high initial rate of entrainment during the first 8 hours of travel (a mass ratio of entrained material to fluid core of about 15% if the average temperature of the entrained material was 600 C), which counterbalances the latent heat from approximately 40% crystallization. In this scenario, the model suggests an additional 5% crystallization and a 5% entrainment mass ratio over the subsequent 16-hour period. Measurements of crystallization, radiative losses, and entrainment factors are necessary for understanding the detailed thermal histories of active lava flows.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B6; p. 11,819-11,831
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  • 72
    Publication Date: 2011-08-24
    Description: The data from the infrared telescope (IRT), which was flown on space shuttle Challenger Spacelab 2 mission (July 1985), were originally reported by Koch et al. (1987) as originating from near orbital emissions, primarily H2O. In this study, analysis of this data was extended to determine the collisional cross sections for the excitation of the low lying vibrational levels of H2O, present in the orbiter cloud, by atmospheric O(3P). The evaluation of the contribution to the measured signal from solar excitation and ram O excitation of outgassing H2O permits the determination of the H2O column density and the excitation cross section of the (101) level at an O(3P) velocity of approximately 7.75 km/s. Contributions to the radiation in the 1.7-3.0 micron band by transitions from the (100), (001), and multiquantum excited levels are discussed. The findings of the study are (1) the IRT data for the 4.5-9.5 micron and the nighttime data for the 1.7-3.0 micron sensors are consistent with being explained by collision excitation of H2O by O(3P), (2) diurnal variations of 4.5-9.5 micron intensities follow the model predicted O density for a full orbit, (3) daytime increases in the H2O cloud density were not evident, (4) the cross sections for the collisional excitation process are derived and compared to values computated by Johnson (1986) and Redmon et al. (1986), (5) theoretical investigation suggests greater than 60% of the radiation from H2O is a result of multiphoton emission resulting from collisional multiquanta excitation, and (6) the large daytime increase in the 1.7-3.0 micron intensity data suggests that O(+) may likely be instrumental in producing excited H2O(+) through charge exchange.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A9; p. 17,559-17,575
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  • 73
    Publication Date: 2011-08-24
    Description: The devolatilization of calcium sulfate, which is present in the target rock of the Chicxulub, Mexico impact structure, and dispersal in the stratosphere of the resultant sulfuric acid aerosol have been suggested as a possible mechanism for the Cretaceous-Tertiary extinctions. We measured the amount of SO2 produced from two shock-induced devolatilization reactions of calcium sulfate up to 42 GPa in the laboratory. We found both to proceed to a much lower extent than calculated by equilibrium thermodynamic calculations. Reaction products are found to be approx. 10(exp -2) times those calculated for equilibrium. Upon modeling the quantity of sulfur oxides degassed into the atmosphere from shock devolatilization of CaSO4 in the Chicxulub lithographic section, the resulting 9 x 10(exp 16) to 6 x 10(exp 17) g (in sulfur mass) is lower by a factor of 10-100 than previous upper limit estimates, the related environmental stress arising from the resultant global cooling and fallout of acid rain is insufficient to explain the widespread K-T extinctions.
    Keywords: GEOPHYSICS
    Type: Earth and Planetary Science Letters (ISSN 0012-821X); 128; 3-4; p. 615-628
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  • 74
    Publication Date: 2011-08-24
    Description: Energetic atomic (O(+1) and N(+1)) and molecular (O2(+1), NO(+1), and N2(+1)) ions of ionospheric origin were observed in Earth's magnetotail at X approximately -146 R(sub E) during two plasma sheet sunward/tailward flow-reversal events measured by instruments on the GEOTAIL spacecraft. These events were associated with concurrent ground-measured geomagnetic disturbance intensification at auroral-and mid-latitudes (Kp = 7(-)). Energetic ions in the sunward-component and tailward flows were from both the solar wind and ionosphere. Plasma and energetic ions participated in the flows. During tailward flow, ionospheric origin ion abundance ratios at approximately 200-900 km/s in the rest frame were N(+1)/O(+1) = approximately 25-30% and ((O2(+1), NO(+1), and N2(+1))/O(+1) = approximately 1-2%. We argue that tailward flow most likely initiated approximately 80-100 R(sub E) tailward of Earth and molecular ions were in the plasma sheet prior to geomagnetic intensification onset.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 25; p. 3023-3026
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  • 75
    Publication Date: 2011-08-24
    Description: Wave forms of BEN (Broadband Electrostatic Noise) in the geomagnetic tail were first detected by the Wave Form Capture reciever on the GEOTAIL spacecraft. The results show that most of the BEN in the plasma sheet boundary layer (PSBL) are not continuous broadband noise but are composed of a series of solitary pulses having a special form which we term 'Electrostatic Solitary Waves (ESW)'. A nonlinear BGK potential model is proposed as the generation mechanism for the ESW based upon a simple particle simulation which considers the highly nonlinear evolution of the electron beam instability. The wave forms produced by this simulation are very similar to those observed by GEOTAIL and suggest that the nonlinear dynamics of the electron beam play an essential role in the generation of ESW.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 25; p. 2915-2918
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  • 76
    Publication Date: 2011-08-24
    Description: We report on the observations of a number of quasi-dc electric field events associated with large-scale atmospheric weather formations. The observations were made by the electric field experiment onboard the San Marco D satellite, operational in an equatorial orbit from May to December 1988. Several theoretical studies suggest that electric fields generated by thunderstorms are present at high altitudes in the ionosphere. In spite of such favorable predictions, weather-related events are not often observed since they are relatively weak. We shall report here on a set of likely E field candidates for atmospheric-ionospheric causality, these being observed over the Indonesian Basin, northern South America, and the west coast of Africa; all known sites of atmospheric activity. As we shall demonstrate, individual events often be traced to specific active weather features. For example, a number of events were associated with spacecraft passages near Hurricane Joan in mid-October 1988. As a statistical set, the events appear to coincide with the most active regions of atmospheric weather.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A10; p. 19,475-19,483
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  • 77
    Publication Date: 2011-08-24
    Description: A radiation model, together with National Meteorological Center temperature observations, was used to compute daily net heating rates in the northern hemisphere (NH) for the Arctic late fall and winter periods of both 1988-1989 and 1991-1992 and in the southern hemisphere (SH) for the Antarctic fall and winters of 1987 and 1992. The heating rates were interpolated to potential temperature (theta) surfaces between 400 K and 2000 K and averaged within the polar vortex, the boundary of which was determined by the maximum gradient in potential vorticity. The averaged heating rates were used in a one-dimensional vortex interior descent model to compute the change in potential temperature with time of air parcels initialized at various theta values, as well as to compute the descent in log pressure coodinates. In the NH vortex, air parcels which were initialized at 18 km on November 1, descended about 6 km by March 21, while air initially at 25 km descended 9 km in the same time period. this represents an average descent rate in the lower stratosphere of 1.3 to 2 km per month. Air initialized at 50 km descended 27 km between November 1 and March 21. In the SH vortex, parcels initialized at 18 km on March 1, descended 3 km, while air at 25 km descended 5-7 km by the end of October. This is equivalent to an average descent in the lower stratosphere of 0.4 to 0.9 km per month during this 8-month period. Air initialized at 52 km descended 26-29 km between March 1 and October 31. In both the NH and the SH, computed descent rates increased markedly with height. The descent for the NH winter of 1992-1993 and the SH winter of 1992 computed with a three-dimensional trajectory model using the same radiation code was within 1 to 2 km of that calculated by the one-dimensional model, thus validating the vortex averaging procedure. The computed descent rates generally agree well with observations of long-lived tracers, thus validating the radiative transfer model.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; D8; p. 16,677-16,689
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  • 78
    Publication Date: 2011-08-24
    Description: The map of the coseismic displacement field generated by interferometric processing of synthetic aperture radar (SAR) images taken before and after the June 28, 1992, Landers earthquake sequence brings new insights into the nature of deformation caused by these earthquakes. We use the interferometric map generated by Massonnet et al. (1993) to analyze the surface displacement field in the vicinity of the fault trace. Complexities in the fringe pattern near the fault reflect short-wavelength variations of the surface rupture and slip distribution, and attest to large displacement gradients. Along two sections of the fault, characteristic fringe patterns can be recognized, contrasting in density and direction with patterns observed away from the rupture. In order to understand the observed fringe patterns, we compute synthetic interferograms in three simple cases: (1) rigid-body rotations about a vertical axis, (2) about a horizontal axis (tilt), and (3) distributed, simple shear. The orientation and spatial separation of interferometric fringes predicted by these models help constrain near-field deformation and rupture parameters. Where the Kickapoo fault connects with the Homestead Valley fault, the interferogram shows a clear pattern of parallel N20 deg W fringes separated by about 160 m. This pattern and vertical offsets measured along the Kickapoo fault suggest that the block between this fault and the Johnson Valley fault may have been tilted, down to the west. A 5-km block lifted by 1 m on one side would be tilted by an angle of 0.01 deg (190 microrad), producing fringes separated by about 160 m, parallel to the tilt axis. Such a tilt, parallel to a N20 deg W direction, would account for the gradual, northward increase of the vertical slip component observed along the Kickapoo fault. This tilt may also explain the 1 m of reverse slip observed along the 'slip gap' section of the Homestead Valley break. Between the southern end of the Johnson Valley fault and the Eureka Peak fault, where no surface rupture has been mapped, the dense pattern of fringes implies distributed shear, probably resulting from fault slip at depth. The density and direction of the fringes in the gap are consistent with a right-lateral slip of 1.2-3.8 m on a blind fault locked above the depth of 1.5-2 km. Such observations of small wavelength features in the SAR interferogram bring new insights into the near-field displacement gradient and thus on response of the uppermost crust to seismic rupture.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B11; p. 21,971-21,981
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  • 79
    Publication Date: 2011-08-24
    Description: The acceleration of protons in a dynamically evolving magnetotail is investigated by tracing particles in the fields obtained from a three-dimensional resistive magnetohydrodynamic (MHD) simulation. The MHD simulation, representing plasmoid formation and ejection through a near-Earth reconnection process, leads to cross-tail electric fields of up to approximately 4 mV/m with integrated voltages across the tail of up to approximately 200 kV. Energization of particles takes place over a wide range along the tail, due to the large spatial extent of the increased electric field together with the finite cross-tail extent of the electric field region. Such accelerated particles appear earthward of the neutral line over a significant portion of the closed field line region inside of the separatrix, not just in the vicinity of the separatrix. Two different acceleration processes are identified: a 'quasi-potential' acceleration, due to particle motion in the direction of the cross-tail electric field, and a 'quasi-betatron' effect, which consists of multiple energy gains from repeated crossings of the acceleration region, mostly on Speiser-type orbits, in the spatially varying induced electric field. The major source region for accelerated particles in the hundreds of keV range is the central plasma sheet at the dawn flank outside the reconnection site. Since this source plasma is already hot and dense, its moderate energization by a factor of approximately 2 may be sufficient to explain the observed increases in the energetic particle fluxes. Particles from the tail are the source of beams at the plasma sheet/lobe boundary. The temporal increase in the energetic particle fluxes, estimated from the increase in energy gain, occurs on a fast timescale of a few minutes, coincident with a strong increase in B(sub z), despite the fact that the inner boundary ('injection boundary') of the distribution of energized particles is fairly smooth.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A1; p. 109-119
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  • 80
    Publication Date: 2011-08-24
    Description: A high-precision radiometric satellite tracking system, Doppler Orbitography and Radio-positioning Integrated by Satellite system (DORIS), has recently been developed by the French space agency, Centre National d'Etudes Spatiales (CNES). DORIS was designed to provide tracking support for missions such as the joint United States/French TOPEX/Poseidon. As part of the flight testing process, a DORIS package was flown on the French SPOT 2 satellite. A substantial quantity of geodetic quality tracking data was obtained on SPOT 2 from an extensive international DORIS tracking network. These data were analyzed to assess their accuracy and to evaluate the gravitational modeling enhancements provided by these data in combination with the Goddard Earth Model-T3 (GEM-T3) gravitational model. These observations have noise levels of 0.4 to 0.5 mm/s, with few residual systematic effects. Although the SPOT 2 satellite experiences high atmospheric drag forces, the precision and global coverage of the DORIS tracking data have enabled more extensive orbit parameterization to mitigate these effects. As a result, the SPOT 2 orbital errors have been reduced to an estimated radial accuracy in the 10-20 cm RMS range. The addition of these data, which encompass many regions heretofore lacking in precision satellite tracking, has significantly improved GEM-T3 and allowed greatly improved orbit accuracies for Sun-synchronous satellites like SPOT 2 (such as ERS 1 and EOS). Comparison of the ensuing gravity model with other contemporary fields (GRIM-4C2, TEG2B, and OSU91A) provides a means to assess the current state of knowledge of the Earth's gravity field. Thus, the DORIS experiment on SPOT 2 has provided a strong basis for evaluating this new orbit tracking technology and has demonstrated the important contribution of the DORIS network to the success of the TOPEX/Poseidon mission.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B2; p. 2791-2813
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  • 81
    Publication Date: 2011-08-24
    Description: The presence of anisotropic plasma distributions, trapped at the Earth's magnetic equator, has consequences for the electric field structure which must exist in equilibrium along the magnetic field line. Data from SCATHA and Dynamics Explorer 1 indicate that the core ion distributions at the magnetic equator can be well described as bi-Maxwellian distributions, with a perpendicular temperature an order of magnitude larger than the parallel temperature. A collisionless model is developed for the variation in plasma parameters, following the forms developed by Whipple (1977). If the core electron anisotropy is low, the resulting electric field of approximately 0.1 microV/m is pointed away from the equator. Under these conditions the self-consistent electric field will not overcome the effects of magnetic trapping. The resulting potential distribution results in a local maximum in total plasma density at the equator. Only when the electron distribution is primarily field-aligned can there be a density minimum at the equator. Comparisons are made between this model and the observed variations in DE 1 plasma parameters with latitude.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A2; p. 2191-2203
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  • 82
    Publication Date: 2011-08-24
    Description: A combined 3-dimensional circulation model and aerosol microphysical/transport model is used to simulate the dispersion of the Mt. Pinatubo volcanic cloud in the stratosphere for the first few months following the eruption. Radiative heating of the cloud due to upwelling infrared radiation from the troposphere is shown to be an important factor affecting the transport. Without cloud heating, cloud material stays mostly north of the equator, whereas with cloud heating, the cloud is transported southward across the equator within the first two weeks following the eruption. Generally the simulations agree with Total Ozone Mapping Spectrometer (TOMS), Advanced Very High Resolution Radiometer (AVHRR), and Stratospheric Aerosol and Gas Experiment (SAGE) satellite observations showing the latitude distribution of cloud material to be between about 20 deg S and 30 deg N within the first few months. Temperature perturbations in the stratosphere induced by the aerosol heating are generally 1-4 K, in the range of those observed.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 5; p. 369-372
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  • 83
    Publication Date: 2011-08-24
    Description: We use geodetic data from Very Long Baseline Interferometry (VLBI) to determine the pre- and postseismic velocities of two sites. We then place limits on variations in interseismic strain buildup. The 1987 and 1988 Gulf of Alaska earthquakes (each Ms = 7.6) broke the Pacific plate interior. During the earthquakes the Cape Yakataga site moved 78 mm toward southwest. During the 1989 Loma Prieta earthquake (Ms = 7.1) the Fort Ord site moved 48 mm toward north. Baselines (a) from Fairbanks to Cape Yakataga and (b) from Mojave to Fort Ord change at nearly the same rate before and after the earthquakes. Postseismic transients, which we determine from differences between post- and preseismic rates, are minor: at Cape Yakataga the transient is 3 +/- 4 mm in a postseismic interval of 23 months, and at Fort Ord the transient is 6 +/- 5 mm in 21 months. The slip beneath the Loma Prieta rupture needed to generate the Fort Ord transient is 0.22 +/- 0.19 m, one-tenth the coseismic slip (2 m). We analyze elastic lithosphere-viscous asthenosphere models to determine that the characteristic time describing exponential decay in deep fault slip is longer than 6 years. The VLBI measurements are consistent with uniform interseismic strain buildup. They disagree with fast postseismic rates caused by an asthenosphere with very low viscosity.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 5; p. 333-336
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  • 84
    Publication Date: 2011-08-24
    Description: The AEPI (Atmospheric Emissions Photometric Imager) experiment on the ATLAS-1 shuttle mission (launched March 24, 1992) imaged the earth night airglow emission in O2 Atmospheric (0,0) bands, at 762.0 nm. Earthward views of O2 A bands show structure from gravity waves which exhibit extended horizontal structure with horizontal wavelenghts on the order of 50-100 km. These observations of the O2 A (0,0) bands are particularly interesting since in this wavelength the lower atmosphere absorbs all the earth-reflected emissions and most of the spectrally diffuse backgrounds. Herein we present observations of gravity waves using a topside airglow imaging technique.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 21; p. 2283-2286
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  • 85
    Publication Date: 2011-08-24
    Description: Fujii et al. (1994) obtained characteristics of the electrodynamic parameters, that is, field-aligned currents, electric fields, and electron precipitation, which are associted with auroral substorm events in the nighttime sector, through a unique analysis that places the ionospheric measurements of these parameters into the context of a generic substorm determined from global auroral images. In this paper we investigate in considerably more detail the characteristics of the field-aligned currents using data from the same set of passes as the previuos study. We show for the first time that the net upward field-aligned currents throughout the surge and surge horn are sufficient to account for most if not all of the converging currents of the auroral electrojets. Current densities are largest in the surge and surge horn. Current region continuity does not appear to exist across the substorm bulge region. Much of the auroral substorm field-aligned current is composed of filamentary currents and finite current segments at large angles to each other. The westward electrojet may contain large gradients in intensity both in local time and latitude due to sets of localized field-aligned currents. The net downward current for several hours to the west of the surge is insufficient to account for the eastward electrojet, consistent with the concept that this electrojet originates primarily on the dayside. Our pattern of field-aligned currents associated with the surge has common features and also differs significantly from the patterns previously derived from data from radars and ground-based magnetometer arrays. Our pattern is considerably more complex, probably due to the much higher resolution in latitude of the satellite data. It is also larger in area, since our average substorm is much larger than those pertaining to the previous patterns, giving a substorm wedge considerably wider than that obtained from the radar and array data.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A11; p. 21,303-21,325
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  • 86
    Publication Date: 2011-08-24
    Description: An analytical model of the bidirectional reflectance for optically semi-infinite plant canopies has been extended to describe the reflectance of finite depth canopies contributions from the underlying soil. The model depends on 10 independent parameters describing vegetation and soil optical and structural properties. The model is inverted with a nonlinear minimization routine using directional reflectance data for lawn (leaf area index (LAI) is equal to 9.9), soybeans (LAI, 2.9) and simulated reflectance data (LAI, 1.0) from a numerical bidirectional reflectance distribution function (BRDF) model (Myneni et al., 1988). While the ten-parameter model results in relatively low rms differences for the BRDF, most of the retrieved parameters exhibit poor stability. The most stable parameter was the single-scattering albedo of the vegetation. Canopy albedo could be derived with an accuracy of less than 5% relative error in the visible and less than 1% in the near-infrared. Sensitivity were performed to determine which of the 10 parameters were most important and to assess the effects of Gaussian noise on the parameter retrievals. Out of the 10 parameters, three were identified which described most of the BRDF variability. At low LAI values the most influential parameters were the single-scattering albedos (both soil and vegetation) and LAI, while at higher LAI values (greater than 2.5) these shifted to the two scattering phase function parameters for vegetation and the single-scattering albedo of the vegetation. The three-parameter model, formed by fixing the seven least significant parameters, gave higher rms values but was less sensitive to noise in the BRDF than the full ten-parameter model. A full hemispherical reflectance data set for lawn was then interpolated to yield BRDF values corresponding to advanced very high resolution radiometer (AVHRR) scan geometries collected over a period of nine days. The resulting parameters and BRDFs are similar to those for the full sampling geometry, suggesting that the limited geometry of AVHRR measurements might be used to reliably retrieve BRDF and canopy albedo with this model.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; D5; p. 10,577-10,600
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  • 87
    Publication Date: 2011-08-24
    Description: MSIS is an empirical model of the thermosphere based on Mass Spectrometer and Incoherent Scatter data. It provides a description of atmospheric temperature, density, and composition for altitudes higher than 85 kilometers. There are coefficients in MSIS to account for yearly and daily variations, geodetic latitude and longitude, altitude, and solar activity. Variations due to magnetic storms are represented by three-hour magnetic ap indices. The MSIS model enables a more timely prediction of aeronomic densities for specific events, such as rocket flights. The database for this model is a comprehensive summary of rocket flight, satellite, incoherent scatter radar, grenade, and falling sphere measurements. Subsets of data were formed by random selection after sorting on altitude, latitude, time of day, etc. Curve fitting was done with four to five thousand data points at a time. The resulting coefficients are presented in subroutines which calculate thermospheric composition and temperature for a user-supplied position and time. MSIS is written in FORTRAN 77 for use with batch or interactive programs and has been implemented on a DEC VAX series computer operating under VMS 4.3 with a central memory requirement of approximately 25K of 8 bit bytes. MSIS is based on a 1977 thermosphere model and was last updated in 1987 to reflect the CIRA 1986 Neutral Thermosphere Model.
    Keywords: GEOPHYSICS
    Type: GSC-12989
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  • 88
    Publication Date: 2011-08-24
    Description: Continuous optical observations of cusp/cleft auroral activities within approximately equal to 09-15 MLT and 70-76 deg magnetic latitude are studied in relation to changes in solar wind dynamic pressure and interplanetary magnetic field (IMF) variability. The observed latitudinal movements of the cusp/cleft aurora in response to IMF B(sub z) changes may be explained as an effect of a variable magnetic field intensity in the outer dayside magnetosphere associated with the changing intensity of region 1 field-aligned currents and associated closure currents. Ground magnetic signatures related to such currents were observed in the present case (January 10, 1993). Strong, isolated enhancements in solar wind dynamic pressure (Delta p/p is greater than or equal to 0.5) gave rise to equatorward shifts of the cusp/cleft aurora, characteristic auroral transients, and distinct ground magnetic signatures of enhanced convection at cleft latitudes. A sequence of auroral events of approximately equal to 5-10 min recurrence time, moving eastward along the poleward boundary of the persistent cusp/cleft aurora in the approximately equal to 10-14 MLT sector, during negative IMF B(sub z) and B(sub y) conditions, were found to be correlated with brief pulses in solar wind dynamic pressure (0.1 is less than Delta p/p is less than 0.5). Simultaneous photometer observations from Ny Alesund, Svalbard, and Danmarkshavn, Greenland, show that the events often appeared on the prenoon side (approximately equal to 10-12 MLT), before moving into the postnoon sector in the case we study here, when IMF B(sub y) is less than 0. In other cases, similar auroral event sequences have been observed to move westward in the prenoon sector, during intervals of positive B(sub y). Thus a strong prenoon/postnoon asymmetry of event occurence and motion pattern related to the IMF B(sub y) polarity is observed. We find that this category of auroral event sequence is stimulated bursts of electron precipitation that originate from magnetosheath plasma that has accessed that dayside magnetosphere in the noon or near-noon sector, possibly at high latitudes, partly governed by the IMF orientation as well as by solar wind dynamic pressure pulses.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A9; p. 17,323-17,342
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  • 89
    Publication Date: 2011-08-24
    Description: Stratospheric aerosols, collected near 19 km altitude on wire impactors over western North America from August 20, 1991 to May 11, 1993, show strong influence of the June 1991 Mt. Pinatubo eruption. Lognormal size distributions are bimodal; each of the mode radii increases and reaches maximum value at about 15 months after eruption. The second (large particle) mode becomes well developed then, and about 40% of the droplets are larger than 0.4 micron radius. The eruption of Mt. Spurr (Alaska) may also have contributed to this. Sulfate mass loading decays exponentially (e-folding 216 days), similar to El Chichon. Silicates are present in samples only immediately after eruption. Two years after eruption, sulfate mass loading is about 0.4 micrograms/cu m, about an order of magnitude higher than background pre-volcanic values. Aerosol size distributions are still bimodal with a very well-defined large droplet mode.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 12; p. 1129-1132
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  • 90
    Publication Date: 2011-08-24
    Description: Comparisons are presented between Nimbus 7 LIMS (Limb Infrared Monitor of the Stratosphere) mapped temperatures and both Datasonde and sphere in situ rocketsonde temperature measurements. With this approach up to 666 LIMS/Datasonde pairs were obtained for various pressure levels to look for small biases in LIMS temperatures as a function of altitude, latitude and season. Between 10-1 hPa LIMS and Datasonde agree everywhere to better than +/- 2 K with the exception of a warm bias of about 3 K at 2 hPa at high latitudes. However, LIMS is colder than the Datasonde by about 4 K at 0.4 hPa and by about 8-10 K at 0.1 hPa. When compared with the more accurate sphere temperatures the bias at 0.1 hPa is reduced by nearly one-half. These results indicate that the LIMS zonal mean constituent profiles are nearly free of temperature bias, except perhaps at 0.1 hPa.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 12; p. 1145-1148
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  • 91
    Publication Date: 2011-08-24
    Description: The carbon monoxide (CO) reference scale created by the National Oceanic and Atmospheric Administration/Climate Monitoring and Diagnostics Laboratory (NOAA/CMDL) is used to quantify measurements of CO in the atmosphere, calibrate standards of other laboratories and to otherwise provide reference gases to the community measuring atmospheric CO. This reference scale was created based upon a set of primary standards prepared by gravimetric methods at CMDL and has been propagated to a set of working standards. In this paper we compare CO mixing ratios assigned to the working standards by three approaches: (1) calibration against the original gravimetric standards, (2) calibration using only working standards as the reference gas, and (3) calibration against three new gravimetric standards prepared to CMDL. The agreement between these values was typically better than 1%. The calibration histories of CMDL working standards are reviewed with respect to expected rates of CO change in the atmosphere. Using a Monte Carlo approach to simulate the effect of drifting standards on calculated mixing ratios, we conclude that the error solely associated with the maintenance of standards will limit the ability to detect small CO changes in the atmosphere. We also report results of intercalibration experiments conducted between CMDL and the Diode Laser Sensor Group (DACOM) at the NASA Langley Research Center (Hampton, Virginia), and CMDL and the Fraunhofer-Institut (Garmisch-Partenkirchen, Germany). Each laboratory calibrated several working standards for CO using their reference gases, and these results were compared to calibrations conducted by CMDL. The intercomparison of eight standards (CO concentrations between approximately 100 and approximately 165 ppb) by CMDL and NASA agreed to better than +/- 2%. The calibration of six standards (CO concentrations between approximately 50 and approximately 210 ppb) by CMDL and the Fraunhofer-Institut agreed to within +/- 2% for four standards, and to within +/- 5% for all six standards.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; D6; p. 12,833-12,839
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  • 92
    Publication Date: 2011-08-24
    Description: Measurements of the ratio OH/HO2, NO, O3, ClO, and BrO were obtained at altitudes from 15-20 km and latitudes from 15-60 deg N. A method is presented for interpreting the rates of chemical transformations that (1) are responsible for over half the ozone removal rate in the lower stratosphere via reactions of HO2; and (2) control the abundance of HO2 through coupling to nitrogen and halogen radicals. The results show our understanding of the chemical reactions controlling the partitioning of OH and HO2 is complete and accurate and that the potential effects of 'missing chemistry' are strickly constrained in the region of the atmosphere encompassed by the observations. The analysis demonstrates that the sensitivity of the ratio OH/HO2 to changes in NO is described to within 12% by current models. This reduces by more than a factor of 2 the effect of uncertainty in the coupling of hydrogen and nitrogen radicals on the analysis of the potential effects of perturbations to odd notrogen in the lower statosphere.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 23; p. 2539-2542
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  • 93
    Publication Date: 2011-08-24
    Description: Previous observations have shown that during periods of steady magnetospheric convection (SMC) a large amount of magnetic flux crosses the plasma sheet (corresponding to approximately 10 deg wide auroral oval at the nightside) and that the magnetic configuration in the midtail is relaxed (the curent sheet is thick and contains enhanced B(sub Z). These signatures are typical for the substorm recovery phase. Using near-geostationary magnetic field data, magnetic field modeling and a noval diagostic technique (isotropic boundary algorithm), we show that in the near-Earth tail the magnetic confirguration is very stretched during the SMC events. This stretching is caused by an intense, thin westward current. Because of the srongly depressed B(sub Z), there is a large radial gradient in the near-tail magetic field. These signatures have been peviously associated only with the substorm growth phase. Our results indicate that during the SMC periods the magnetic configuration is very peculiar, with co-existing thin near-Earth current sheet and thick midtail plasma sheet. The deep local minimum of the equatorial B(sub Z) that devleops at R approximately 12 R(sub E) is consistent with steady, adiabatic, Earthward convection in the midtail. These results impose contraints on the existing substorm theories, and call for an explanation of how such a stressed configuration can persist for such a long time without tail current disruptions that occur at the end of a substorm growth phase.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A12; p. 23,571-23,582
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  • 94
    Publication Date: 2011-08-24
    Description: We report an observation of Petschek-type magnetic reconnection at a distant neutral line (X = -230 R(sub e)) with a full set of signatures of the magnetic merging process. These features include a reversal of plasma flows from earthward to tailward, a pair of slow shocks and the magnetic field X-type line. These two slow shocks are shown to satisfy the shock criteria used by Feldman et al. (1987). The spacecraft first crosses a slow shock to enter the earthward flowing plasmasheet with velocity of about 440 km/s. The embedded magnetic field has a positive B(sub z) component. The spacecraft next enters a region of tailward plasma flow with speed approximately 670 km/s and an embedded negative B(sub z), indicating entry into the plasmasheet tailward of the X-line. These observed velocities are comparable to calculated velocities based on Rankine-Hugoniot conservation relationships. The spacecraft subsequently returns into the south tail lobe by crossing another slow shock. Coplanarity analyses shows that the two slow shocks have orientations consistent with that predicted by the Petschek reconnection model. We note that this event occurs during northward interplanetary magnetic fields. Thus, a magnetic stress built-up in the distant tail may be responsible for this reconnection process.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 25; p. 3031-3034
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  • 95
    Publication Date: 2011-08-24
    Description: A method is presented for analytically representing the magnetic field due to the cross-tail current and its closure on the magnetopause. It is an extension of a method used by Tsyganenko (1989b) to confine the dipole field inside an ellipsoidal magnetopause using a scalar potential. Given a model of the cross-tail current, the implied net magnetic field is obtained by adding to the cross-tail current field a potential field B = - del gamma, which makes all field lines divide into two disjoint groups, separated by the magnetopause (i.e., the combined field is made to have zero normal component with the magnetopause). The magnetopause is assumed to be an ellipsoid of revolution (a prolate spheroid) as an approximation to observations (Sibeck et al., 1991). This assumption permits the potential gamma to be expressed in spheroidal coordinates, expanded in spheroidal harmonics and its terms evaluated by performing inversion integrals. Finally, the field outside the magnetopause is replaced by zero, resulting in a consistent current closure along the magnetopause. This procedure can also be used to confine the modeled field of any other interior magnetic source, though the model current must always flow in closed circuits. The method is demonstrated on the T87 cross-tail current, examples illustrate the effect of changing the size and shape of the prescribed magnetopause and a comparison is made to an independent numerical scheme based on the Biot-Savart equation.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; A10; p. 19,393-19,402
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  • 96
    Publication Date: 2011-08-24
    Description: We have found that image data acquired with NASA's airborne Thermal Infrared Multispectral Scanner (TIMS) can be used to make estimates of the SO2 content of volcanic plumes. TIMS image data are most applicable to the study of partially transparent SO2 plumes, such as those released during quiescent periods or nonexplosive eruptions. The estimation procedure is based on the LOWTRAN 7 radiative transfer code, which we use to model the radiance perceived by TIMS as it views the ground through an SO2 plume. The input to the procedure includes the altitudes of the aircraft and ground, the altitude and thickness of the SO2 plume, the emissivity of the ground, and altitude profiles of the atmospheric pressure, temperature, and relative humidity. We use the TIMS data to estimate both ground temperatures beneath a plume and SO2 concentrations within a plume. Applying our procedure to TIMS data acquired over Mount Etna, Sicily, on July 29, 1986, we estimate that the SO2 flux from the volcano was approximately 6700 t d(exp -1). The use of TIMS to study SO2 plumes represents a bridge between highly localized methods, such as correlation spectroscopy or direct sampling, and small-scale mapping techniques involving satellite instruments such as the Total Ozone Mapping Spectrometer or Microwave Limb Sounder. We require further airborne experiments to refine our estimation procedure. This refinement is a necessary preparation for the schedueled 1998 launch of the Advanced Spaceborne Thermal Emission and Reflectance Radiometer, which will allow large-scale multispectral thermal infrared image data to be collected over virtually any volcano on Earth at least once every 16 days.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B1; p. 481-488
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  • 97
    Publication Date: 2011-08-24
    Description: We determine the improvement in baseline length precision and accuracy using new atmospheric delay mapping functions and MTT by analyzing the NASA Crustal Dynamics Project research and development (R&D) experiments and the International Radio Interferometric Surveying (IRIS) A experiments. These mapping functions reduce baseline length scatter by about 20% below that using the CfA2.2 dry and Chao wet mapping functions. With the newer mapping functions, average station vertical scatter inferred from observed length precision (given by length repeatabilites) is 11.4 mm for the 1987-1990 monthly R&D series of experiments and 5.6 mm for the 3-week-long extended research and development experiment (ERDE) series. The inferred monthly R&D station vertical scatter is reduced by 2 mm or by 7 mm is a root-sum-square (rss) sense. Length repeatabilities are optimum when observations below a 7-8 deg elevation cutoff are removed from the geodetic solution. Analyses of IRIS-A data from 1984 through 1991 and the monthly R&D experiments both yielded a nonatmospheric unmodeled station vertical error or about 8 mm. In addition, analysis of the IRIS-A exeriments revealed systematic effects in the evolution of some baseline length measurements. The length rate of change has an apparent acceleration, and the length evolution has a quasi-annual signature. We show that the origin of these effects is unlikely to be related to atmospheric modeling errors. Rates of change of the transatlantic Westford-Wettzell and Richmond-Wettzell baseline lengths calculated from 1988 through 1991 agree with the NUVEL-1 plate motion model (Argus and Gordon, 1991) to within 1 mm/yr. Short-term (less than 90 days) variations of IRIS-A baseline length measurements contribute more than 90% of the observed scatter about a best fit line, and this short-term scatter has large variations on an annual time scale.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 99; B1; p. 637-651
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  • 98
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    In:  Other Sources
    Publication Date: 2011-08-24
    Description: Vertical ocean loading amplitudes are determined by analysis of IRIS geodetic Very Long Baseline Interferometry (VLBI) data. The 4 nearly diurnal (K(sub 1), P(sub 1), O(sub 1), Q(sub 1)) and 4 nearly semidiurnal (K(sub 2), S(sub 2), M(sub 2), and N(sub 2)) component amplitudes can be inferred from the data with accuracies of 1-2 mm. Uncertainties of total displacements can approach 1 cm. Empirically determined total displacements are considerably larger than the values calculated from two geophysical models. The Scherneck model is found to give a better representation of VLBI delay data than the model of Pagiatakis by about 3 mm in residuals at 6 sites. Empirical estimation of the ocean loading amplitudes reduces Chi squared by 3067 for the 96 additional degrees of freedom in a fit to 273,000 IRIS VLBI observations, and reduces the RMS residuals by 3 mm relative to a fit using the fixed Scherneck model. Vertical ocean loading amplitudes can thus be inferred from VLBI data at a level which improves the overall model, but detailed assessment of individual tidal components is presently obscured by incomplete modeling at the tidal frequencies.
    Keywords: GEOPHYSICS
    Type: Geophysical Research Letters (ISSN 0094-8276); 21; 5; p. 357-360
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  • 99
    Publication Date: 2011-08-24
    Description: We explore the implications of indicating the biosphere's self-organization by the trend over time of the net entropic flow from the Earth's surface, the actual physical boundary of virtually all biotic mass. This flow, derived from the radiative surface entropy budget, is approximately inversely related to the surface temperature when the solar incident flux remains constant. In the geophysiological ('gaian') interpretation, biospheric self-organization has increased with the progressive colonization of the continents and evolutionary developments in the land biota, as a result of surface cooling arising from biotic enhancement of weathering. The key site for this self-organization is at the interface between land and atmosphere, the soil, where carbon is sequestered by its reaction (as carbonic and organic acids) with calcium magnesium silicates. Along with disequilibrium (steady-state) levels of carbon dioxide in the atmosphere, the occurrence of differentiated soil is the critical material evidence for biospheric self-organization, whether it be geophysiological or geochemical (ie., purely result of inorganic reactions). The computed equilibrium levels of carbon dioxide and corresponding equilibrium temperatures in the past are dramatically different from the steady-state levels. With future solar luminosity increase, the biospheric capacity for climatic regulation will decrease, leading to the ending of self-organization some two billion years from now. The Earth's surface will then approach chemical equilibrium with respect to the carbonate-silicate cycle.
    Keywords: GEOPHYSICS
    Type: Origins of Life and Evolution of the Biosphere (ISSN 0169-6149); 24; 5; p. 435-450
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  • 100
    Publication Date: 2011-08-24
    Description: By the middle of the decade, several new Laser Geodynamic Satellites will be launched to join the current constellation comprised of the laser geodynamic satellite (LAGEOS) (US), Starlette (France), Ajisai (Japan), and Etalon I and II (USSR). The satellites to be launched, LAGEOS II and III (US & Italy), and Stella (France), will be injected into orbits that differ from the existing constellation so that geodetic and gravimetric quantities are sampled to enhance their resolution and accuracy. An examination of various possible tracking strategies adopted by the network of laser tracking stations has revealed that the recovery of precise geodetic parameters can be obtained over shorter intervals than is currently obtainable with the present constellation of satellites. This is particularly important in the planning of mobile laser tracking operations, given a network of permanently operating tracking sites. Through simulations, it is shown that laser tracking of certain satellite passes, pre-selected to provide optimal sky-coverage, provides the means to acquire a sufficient amount of data to allow the recovery of 1 cm station positions.
    Keywords: GEOPHYSICS
    Type: Satellite Orbits; Technical Panel on Satellite Dynamics (Meeting P1) of the COSPAR Plenary Meeting, 29th, Washington, DC, August 28-September 5, 1992 . A95-61505 (ISSN 0273-1177); 14; 5; p. (5)27-(5)33
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