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Your search keyword '"D. Charles"' showing total 57 results
Start Over Author "D. Charles" Publisher american association for the advancement of science
57 results on '"D. Charles"'

1. Millennial-scale instability of the Antarctic Ice Sheet during the last glaciation

Author

P. Graham Mortyn, Christopher D. Charles, Thomas P. Guilderson, Ulysses S Ninnemann, David A. Hodell, Sharon L. Kanfoush, and Marine Biogeology

Subjects
geography, Multidisciplinary, geography.geographical_feature_category, North Atlantic Deep Water, Ocean current, Antarctic ice sheet, Ice shelf, Oceanography, Glacial period, Stadial, SDG 14 - Life Below Water, Ice sheet, Geology, Ice rafting
Abstract

Records of ice-rafted detritus (IRD) concentration in deep-sea cores from the southeast Atlantic Ocean reveal millennial-scale pulses of IRD delivery between 20,000 and 74,000 years ago. Prominent IRD layers correlate across the Polar Frontal Zone, suggesting episodes of Antarctic Ice Sheet instability. Carbon isotopes (δ 13 C) of benthic foraminifers, a proxy of deepwater circulation, reveal that South Atlantic IRD events coincided with strong increases in North Atlantic Deep Water (NADW) production and inferred warming (interstadials) in the high-latitude North Atlantic. Sea level rise or increased NADW production associated with strong interstadials may have resulted in destabilization of grounded ice shelves and possible surging in the Weddell Sea region of West Antarctica.

Published
2000
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2. An egg-adult association, gender, and reproduction in pterosaurs

Author

Lu, Junchang, Unwin, David M., Deeming, D. Charles, Jin, Xingsheng, Liu, Yongqing, Ji, Qiang, Lu, Junchang, Unwin, David M., Deeming, D. Charles, Jin, Xingsheng, Liu, Yongqing, and Ji, Qiang

Abstract

A sexually mature individual of Darwinopterus preserved together with an egg from the Jurassic of China provides the first direct evidence of gender in pterosaurs and unique insights into the reproductive biology of these extinct fliers. The new find and several other examples of Darwinopterus demonstrate that males of this pterosaur had relatively small pelves and a large cranial crest, while females had relatively large pelves and no crest. The egg mass/adult mass index is relatively low, as in extant reptiles, and comparable to values for squamates. A parchment-like eggshell points to burial and significant uptake of water post oviposition. This “low investment strategy” contradicts the widespread assumption that reproduction in pterosaurs was like that of birds and shows that it was essentially reptilian.

3. An Egg-Adult Association, Gender, and Reproduction in Pterosaurs.

Author

Junchang Lü, Unwin, David M., Deeming, D. Charles, Xingsheng Jin, Yongqing Liu, and Qiang Ji

Subjects
*PTEROSAURIA, *FOSSIL reptiles, *REPRODUCTION, *ANATOMY, *EGGS, *JURASSIC stratigraphic geology
Abstract

A sexually mature individual of Darwinopterus preserved together with an egg from the Jurassic of China provides direct evidence of gender in pterosaurs and insights into the reproductive biology of these extinct fliers. This new find and several other examples of Darwinopterus demonstrate that males of this pterosaur had a relatively small pelvis and a large cranial crest, whereas females had a relatively large pelvis and no crest. The ratio of egg mass to adult mass is relatively low, as in extant reptiles, and is comparable to values for squamates. A parchment-like eggshell points to burial and significant uptake of water after oviposition. This evidence for low parental investment contradicts the widespread assumption that reproduction in pterosaurs was like that of birds and shows that it was essentially like that of reptiles. [ABSTRACT FROM AUTHOR]

Published
2011
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7. Off the grid.

Author

Charles D

Abstract

Computer models that forecast overloaded power lines are holding back U.S. solar and wind energy projects.

Published
2023
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20. The 2010 budget. Navigating treacherous waters.

Author

Charles D, Kaiser J, Kintisch E, and Stokstad E

Subjects
Greenhouse Effect, National Institutes of Health (U.S.) economics, National Institutes of Health (U.S.) organization & administration, Public Policy, Technology, United States, United States Environmental Protection Agency legislation & jurisprudence, United States Environmental Protection Agency organization & administration, Biomedical Research economics, Budgets, Science
Published
2009
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21. Biofuels. Corn-based ethanol flunks key test.

Author

Charles D

Subjects
Agriculture, California, Conservation of Natural Resources, Gasoline standards, Greenhouse Effect, State Government, United States, United States Environmental Protection Agency, Vehicle Emissions legislation & jurisprudence, Energy-Generating Resources standards, Ethanol, Government Regulation, Zea mays
Published
2009
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32. Susan Dudley profile. Decision on lead emissions weighs heavily on EPA.

Author

Charles D

Subjects
Child, Humans, Maximum Allowable Concentration, United States, Air Pollutants adverse effects, Air Pollutants analysis, Air Pollution legislation & jurisprudence, Government Regulation, Lead adverse effects, Lead analysis, United States Environmental Protection Agency legislation & jurisprudence
Published
2007
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39. Agbiotech. Seeds of discontent.

Author

Charles D

Subjects
Crosses, Genetic, Developing Countries, Genetic Variation, Zea mays genetics, Biotechnology, Crops, Agricultural genetics, Ecosystem, International Cooperation, Seeds
Published
2001
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43. Ethics and the use of drugs during pregnancy.

Author

Sabath LD, Philipson A, and Charles D

Subjects
Aborted Fetus, Ampicillin blood, Anti-Bacterial Agents administration & dosage, Female, Humans, Informed Consent, Maternal-Fetal Exchange, Ethics, Medical, Pregnancy drug effects, Pregnant People
Published
1978
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